WO2007028053A2 - Methods of treating and preventing cardiac disorders - Google Patents

Abstract

The present disclosure provides methods and compositions for treating coronary tissue damaged as a result of a cardiac disorder such as ischemia, acute myocardial infarction, vulnerable plaques, or reperfusion injury. Specifically, the cardiac disorder is treated using a locally-delivered therapeutic molecule.

Description

METHODS OF TREATING AND PREVENTING CARDIAC DISORDERS

Background Of The Invention

One of the greatest unmet clinical needs in interventional cardiology is amelioration or elimination of damage to heart tissue as a result of cardiac insult such as that caused by occluded coronary arteries - acute myocardial infarction (AMI). Not only does infarcted tissue decline due to lack of blood perfusion, but upon opening of the artery, the rapid reperfusion of the infarcted region also causes damage, inter alia cardiomyocyte apoptosis. In some instances, the long-term result of such damage is a permanent remodeling of ventricular tissue into a "scar" that is characterized by a thinning ventricular wall and expanded ventricular cavity. The scar region does not contain sufficient cardiomyocytes, vascular cells, fibroblasts, and/or nerve cells to sustain the normal pattern of depolarization propagation and/or contraction for efficiently pumping of blood. Reduced blood flow, associated with clinically measurable indications such as decreased contraction force, decreased ejection fraction, increased left ventricular (LV) volume, and increased LV wall stress, are the frequent sequela of AMI.

There are several clinical approaches to preventing AMI or reducing the damage caused by AMI, falling into three main categories: drug treatment; gene therapy; and cell therapy. Drug treatment includes delivery of medications intended to reverse the causes of AMI such as thrombolytics, known heart medications such as beta blockers, antihypertensive medications such as ACE inhibitors, or anti-platelet medications such as aspirin. Gene therapy includes, the local or systematic delivery of DNA or viruses encoding genes intended to induce cardiac angiogenesis or myogenesis. Cell therapy includes surgically introducing cells directly into the heart muscle; injecting cells from inside the heart via catheter-mounted syringes using standard interventional techniques; introducing cells into a coronary artery, whence they would be carried by the blood downstream into the injured zone; or introducing cells intravenously. Other techniques include, for example, the enhancement of the healing properties of blood through super- oxygenization or other ex-vivo blood treatment.

Cell therapy approaches to AMI present many challenges including, for example, the inefficient injection of cells whereby only a few of the injected cells remain at the site of injection; the poor survival of transplanted cells; the choice or selection of cell type that is the most beneficial; the expensive and time consuming processes for harvesting and ex vivo expansion of autologous cells; and the complex clinical procedures required to introduce these cells into the heart of a patient. Likewise, gene therapy is an impractical approach due to low efficiency of delivery, the inability to precisely control dose, potential toxicity in non-target tissues, and difficulties in choosing appropriate gene constructs.

Two major categories of drug treatment for AMI may be defined. The first, anti- thromlotic therapy, reduces or eliminates coronary artery thrombi that occlude the coronary arteries and cause hypoxia. Examples include: fibrinolytic agents such as intravenous streptokinase or tissue plasminogen activator; anti-coagulant agents such as aspirin, heparin, and factor Xa inhibitors; platelet inhibitors (GP Ilb/IIIa receptor inhibitors) such as abciximab and tirofiban; and other inhibitors of platelet aggregation such as clopidogrel (Antman and Van de Werf, Circulation, 109:2480-2486, 2004). In recent years treatment regimens have been developed and widely used, typically consisting of combinations of the above therapeutic agents, both to dissolve occluding thrombi which have formed in coronary arteries (often being the root cause of myocardial infarctions) and for the prevention of subsequent thrombi during and after percutaneous transluminal coronary angioplasty (PTCA) procedures and stent implantation.

The second category of drug treatments for AMI is the subject of the present invention, called pharmacological modulators of AMI (PMAMI). This consists of therapies intended to reduce the size and extent of myocardial damage due to coronary artery occlusion, prevent or ameliorate injury due to reperfusion of the infarcted zone, reduce post-reperfusion ventricular remodeling, enhance regeneration of damaged tissue, and/or reverse secondary diseases resulting from AMI such as cardiac fibrosis. Such therapies target specific modes of action such as anti-apoptosis, modulation of differentiation, cardio-protection, or angiogenesis. Drug treatments from this category, that are intended to ameliorate the effects of AMI. These are usually administered in conjunction with an anti-thrombosis drug regimen.

Accordingly, it is an object of this invention to provide improved methods and compositions for the treatment of cardiac disorders, including acute myocardial infarction. Summary Of The Invention

The present in disclosure provides methods and compositions for treating cardiac disorders. In one aspect, the invention provides a method for treating a cardiac disorder in a patient by locally administering to the patient a therapeutic molecule encapsulated in a microparticle. In a related aspect, the invention provides an implantable device comprising a therapeutic molecule encapsulated in a microparticle, wherein the therapeutic molecule is capable of treating a cardiac disorder. In either of the foregoing aspects, the therapeutic molecule is an estrogen (e.g., 17β-estradiol), estrogen receptor agonists, a prostaglandin EP₃ receptor agonist, a caspase inhibitor, a potassium channel opener, a nitric oxide donor (e.g., nicorandil), an aldosterone receptor antagonist (e.g., spironolactone and eplerenone), a compound that block platelet-endothelial cell adhesion molecules (e.g., PECAM-I), IL-6/sIL-6R or IL-6, a GP130 agonist, an IL- 18 antagonist, a glycosaminoglycan analog (e.g., dextran sulfate), a plasminogen activator inhibitor- 1 antagonist, relaxin, clusterin, a p38 MAP kinase inhibitor (e.g., SB203580), a cardiac regeneration factor (e.g. CRF-I and CRF-2), insulin-like growth factor 1 (IGF-I), hepatocyte growth factor (HGF), growth- differentiation factor- 15 (GDF- 15), hypoxia inducible factor- 1 (HIF-I), a TNF-α inhibitor, a CD- 147 inhibitor, a PDGF agonist, or a neutrophil gelatinase-associated lipocalin (NGAL) inhibitor.

Cardiac disorders amenable to treatment by this method include, for example, acute myocardial infarction, a chronic ischemic condition, reperfusion injury, chronic heart disease, vulnerable plaques, and cardiac fibrosis.

The therapeutic molecule is locally administered by any appropriate route or using any appropriate technique including, for example, intravenous or intra-arterial injection, during percutaneous transluminal coronary angioplasty (including delivery using a PCTA balloon), and via an implantable device (e.g., a stent). The therapeutic molecule may be present as a free base, salt, or bound as a conjugate to another molecule.

In useful embodiments, the therapeutic molecule is encapsulated in a liposome or a polymeric microsphere. Useful polymeric microspheres include those produced using an aqueous/aqueous emulsion system. In some embodiments, the microspheres contain dextran, PEG, or PLGA. By "cardiac disorders" is meant any disease or disorder of the cardiac tissue, particularly the cardiac muscle, associated with or caused by an ischemic condition, reduction in blood flow, physical trauma (e.g., associated with injury or a surgical procedure). Cardiac disorders include, but are not limited to, AMI, acute or chronic ischemic conditions, reperfusion injury, chronic heart disease (CHD), vulnerable plaques (VP), and cardiac fibrosis.

By "coronary tissue" is meant the cardiac muscle, consisting of fused cardiomyocytes, and ancillary cell types whose presence is critical, but are found in much smaller numbers. Examples of such cell types are vascular cells (including endothelial and smooth muscle cells), fibroblasts and other connective tissue cells, neurons and other types of nerve cells, and progenitor cells such as cardiac stem cells (Beltrami et al., Cell, 114:763-776, 2003). Coronary tissue also includes the extracellular matrix and associated molecules surrounding the foregoing cellular components.

By "percutaneous transluminal coronary angioplasty (PTCA)" is meant a procedure for treating heart disease in which a catheter assembly having a balloon portion is introduced percutaneously into the cardiovascular system of a patient via the brachial or femoral artery. The catheter assembly is advanced through the coronary vasculature until the balloon portion is positioned across the occlusive lesion. Once in position across the lesion, the balloon is inflated to a predetermined size to radially compress against the atherosclerotic plaque of the lesion to remodel the vessel. The balloon is then deflated to a smaller profile to allow the catheter to be withdrawn from the patient's vasculature.

By an "effective amount," in reference to a therapeutic molecule or composition, is meant an amount of a molecule, compound or composition, alone or in a combination according to the invention, required to affect a therapeutic response (i.e., treatment of cardiac disorders). The effective amount of active compound(s) used to practice the present invention for therapeutic treatment of cardiac disorders (e.g., AMI) varies depending upon the manner of administration, the age, body weight, and general health of the subject. Ultimately, the attending medical professional will decide the appropriate amount and dosage regimen. Such amount is referred to as an "effective" amount. By "treating" is meant administering a therapeutic molecule for the purpose of improving the condition of a patient by reducing, alleviating, or reversing at least one adverse effect or symptom.

Brief Description Of The Drawings

FIGURE 1 is a schematic diagram showing components of a system for the treatment of myocardial infarction and its effects. The formulated treatment is introduced by any convenient route (e.g., injection through a catheter into the artery feeding the infarcted zone and/or eluted from a stent placed in the artery feeding the infarcted zone). Targets sites for therapy include the infarcted zone and surrounding border regions that are served by the coronary artery(ies) that had previously been occluded.

Detailed Description Of The Invention

The present invention provides methods and compositions for treating coronary tissue damaged as a result of a cardiac disorder such as ischemia, AMI, or reperfusion injury. The treatment may be administered by any appropriate method including, for example, via an implantable stent, via a drug-delivery PTCA balloon, as a locally injected bolus during PTCA, or via intracoronary or intravenous injection.

Therapeutic Molecules

There are several specific target regions within the infarcted or diseased zone of the heart that are therapeutic targets. For an established myocardial infarction, the scar resulting from ischemic cell death and healing is the least responsive to therapy because the endogenous cardiac tissue capable of functioning in coordination with the rest of the heart has been replaced by non-functional scar tissue cells and extracellular matrices. Tissue in areas surrounding the scar border regions is reported to be progressively more functional and thus more capable of generating, supporting, and incorporating new cells that form or support functional tissue. Tissue that has undergone ischemia, but has not yet undergone apoptosis, necrosis, or scarring, is another target for therapy insofar as timely treatment (e.g. during a PTCA procedure taking place as soon as possible after the onset of symptoms), could slow or reverse the decline of this tissue via ischemia or reperfusion injury.

There are a variety of classes of therapeutic molecules that may be used to reduce and/or reverse the damage caused by AMI or another cardiac disorder. Any of these therapeutics may be used in accordance with the principles of this disclosure. Examples of useful therapeutic molecules include, for example: estrogen (e.g., 17β-estradiol), estrogen receptor agonists, prostaglandin EP₃ receptor agonists, caspase inhibitors, potassium channel openers, nitric oxide donors (e.g., nicorandil), aldosterone receptor antagonists (e.g., spironolactone and eplerenone), compounds that block platelet-endothelial cell adhesion molecules (e.g., PECAM-I), IL-6/sIL-6R or IL-6, GP130 agonists, IL-18 antagonists, glycosaminoglycan analogs (e.g., dextran sulfate), plasminogen activator inhibitor-1 antagonists, relaxin, clusterin, inhibitors of p38 MAP kinase (e.g., SB203580), cardiac regeneration factors (e.g. CRF-I and CRF-2), insulin-like growth factor 1 (IGF-I), hepatocyte growth factor (HGF), growth-differentiation factor- 15 (GDF- 15), hypoxia inducible factor- 1 (HIF-I), a TNF-α inhibitor, a CD- 147 inhibitor, a PDGF agonist, and a neutrophil gelatinase-associated lipocalin (NGAL) inhibitor.

17β-estradiol (estrogen, E2) is an endogenous steroid hormone found in men and women, and is the predominant female sex hormone. The anti-atherogenic properties of estrogen have been known for many years. Numerous clinical and experimental studies have demonstrated that estrogen improves the lipid profile and has direct protective effects on the vasculature (Barrett-Connor, Circulation, 95:252-264, 1997; Stampfer et al, N Engl J Med, 325:756-762, 1991; Mendelsohn and Karas, N Engl J Med, 340:1801-1811, 1999). Gender differences in cardiovascular disease are well recognized (Farhat et al, FASEB J, 10:615-624, 1996). Cardiovascular disease is rare in premenopausal women and the Framingham Study suggested that prior to menopause the incidence of ischemic heart disease in women is considerably less than that of males (Lerner and Kannel, American Heart Journal, 111:383-390, 1986). The lower mortality from ischemic heart disease among premenopausal women is largely due to endogenous circulating estrogens and, when estrogen production subsides following the menopause, there is a sharp increase in mortality (Colditz et al, NEnglJMed, 316:1105-1110, 1987). Premature menopause from bilateral oophorectomy is also associated with an increase in coronary artery disease (Barrett-Connor and Bush, JAMA, 265:1861-1867). has increased in recent years, with significant effort being devoted to development of a variety of detection methods such as intravascular ultrasound (IVUS), optical coherence tomography, intravascular magnetic resonance imaging, coronary spectroscopy, and intracoronary thermography (MacNeill et al, Arterioscler Thromb Vase Biol, 23:1333- 5 1342, 2003; El-Shafei and Kern, J Invas Card, 14:129-137, 2002). In addition, efforts are ongoing to establish the presence of soluble factors in blood, or serum markers, that would serve to identify the existence of VP which in turn could predict the onset of plaque rupture, which ultimately leads to the often fatal acute coronary syndrome (ACS) as well as to AMI. Several serum markers have been proposed to be used for this purpose: 0 troponin-T, C-reactive protein, oxidized LDL, and soluble CD40 ligand, soluble ICAM-I, E-selectin, and soluble LOX-I. For purposes of treatment with PMAMI, the therapeutic molecule are delivered such that regions of the coronary arteries containing VP will receive an effective dose of the molecule in addition to the target infarcted region of the heart.

Administration of Therapeutic Molecules 5 Among the therapeutic molecules potentially useful in accordance with the principles of this disclosure, the route of administration could be either systemic (whether oral or parenteral) or, as in the present invention, delivered locally to the site of action. For a variety of reasons, local delivery of the therapeutic molecule(s) is the most useful route of administration. First, the coronary artery whose occlusion is the root cause of AMI or 0 other occlusive ischemic injury provides blood directly and specifically to the site of damage. Second, the effective dose is much reduced for local administration because the target tissue for the therapeutic molecule (diseased portion of the heart) is less than 1% of the body mass served by systemic drug delivery. Third, a large majority of patients suffering from an occlusive ischemic injury undergo PTCA (nearly always including stent 5 implantation) which provides a unique opportunity to deliver the therapeutic molecule to the coronary artery in question, in an efficient and cost effective manner. Finally, the dosage and duration of treatment may be accurately controlled when locally delivered to the coronary artery. Local delivery is achieved by direct injection via catheter into the coronary artery lumen during the PTCA procedure or by injection of a controlled-release 0 formulation such as encapsulation in degradable microparticles. Alternatively, the therapeutic molecule is delivered from coatings on indwelling devices, such as stents, that are implanted during PTCA, and elute the therapeutic molecule into the coronary artery lumen and hence directly into the infarcted zone. The therapeutic molecule instead may be delivered via other devices such as drug-delivery balloons into the wall or lumen of the coronary artery, either alone, in microparticles or nanoparticles, or in other controlled release formulations. Finally, the therapeutic molecule may be delivered via direct injection into the infarcted region of the cardiac wall from an intramyocardial injection catheter (Boston Scientific Corporation Stiletto™ endocardial direct injection catheter system; Marshall et al, Molecular Therapy, 1:423-429, 2000; Karmarkar et al, Magnetic Resonance in Medicine, 51 : 1163-1172, 2004).

The therapeutic molecule used for treating a cardiac disorder are locally administered by any appropriate method. Methods for administration include, for example, intravenous or intra-arterial injection, a bolus injection via a catheter during PCTA, a coated or impregnated implantable device such as a stent, and injection directly into the target tissue, i.e. in and around the infarcted region of the heart. FIGURE 1 is a schematic showing one example of administration by intra-arterial injection. Examples of implantable devices and stents that may be used in the present invention include, but are not limited to, those described in U.S. Patent Nos. 6,709,379, 6,273,913, 5,843,172,

4,355,426, 4,101,984, 3,855,638, 5,571,187, 5,163,958 and 5,370,684; U.S. Patent

Publications US2002/0098278 and US2004/0073284; PCT International Published Patent

Application No. WO 2004/043292; and European Published Patent Application No. EP 0875218.

Delivery of therapeutic molecules upstream of the site of AMI, from which point they would be carried by the flow of blood to the site of AMI, may be accomplished through the use of standard interventional devices including, but not limited to, drug- eluting stents, drug-delivery balloons, or PTCA catheters. In each case, the molecules are ultimately delivered into the lumen of the coronary artery whose occlusion resulted in hypoxia and infarction. Therapeutic molecules may be formulated in a variety of conventional pharmaceutical carriers including saline, emulsifiers, or microparticles. Additionally, the molecules may be coated on a coronary stent either alone or embedded in polymers or other natural or synthetic carriers, for controlled elution into the lumen of the coronary artery. In every case, the therapeutic molecules will be taken via the coronary arterial system into the region of the heart that was subject to damage by ischemia. Typically, the same coronary artery lesion that is undergoing treatment by PTCA and/or

10 stenting will have been the cause of the arterial blockage that would lead to AMI due to ischemic and/or reperfusion injury. Delivery of therapeutic molecules into the arterial lumen at the site of intervention will effectively provide treatment to the precise site of coronary damage.

In one embodiment, therapeutic molecules are delivered via one or both of two methods during the same interventional procedure, typically but not limited to PTCA. For example, a first dose is administered via catheter-based injection of therapeutic molecules (formulated in one or more ways, such as in saline, in a pharmaceutical excipient, or encapsulated in microparticles or nanoparticles) directly into the coronary arterial lumen, in the region of PTCA and stent placement, using the balloon catheter itself or a separate catheter (Guzman et al, Circulation, 94:1441-1448, 1996). The second administration of the same or a different therapeutic molecule is via a coating on the coronary stent. Optionally, at least one therapeutic compound is embedded in a degradable or non- degradable polymer or natural coating, or alternatively formulated as microparticles which are themselves embedded in a polymeric or other type of coating, and subsequently these coatings are applied to the surface of the coronary stent. Therapeutic molecules elute from the coating into the lumen of the coronary artery either by diffusion from the polymeric coating or by degradation of the coating, thus releasing the therapeutic molecules.

For local delivery by drug delivery balloons, the therapeutic molecule in a liquid formulation is loaded into devices such as a triple-lumen balloon catheter (Infiltrator, manufactured by Interventional Technology; Kaul et al, Circulation, 107:2551-2554, 2003), or a channel balloon catheter (Boston Scientific) from which the drug is injected into the arterial wall, and thence released into the arterial lumen, from where it flows into the coronary infarcted zone.

Many, if not all, situations in which a blocked artery is re-opened via PTCA result in some level of reperfusion injury. Introduction of PMAMI enhances the repopulation of such injured regions with beneficial cells, thus reducing the extent or duration of injury.

Pharmaceutical Formulations

The therapeutic molecules may be formulated in a variety of ways depending upon the route of administration. For direct intravenous or intra-arterial injection, any standard

11 injectable carrier known in the art may be used. The most common formulations are aqueous solutions including, for example, normal saline, Ringers, and 5% dextrose solutions Pharmaceutical compositions according to the present invention may also comprise binding agents, filling agents, lubricating agents, disintegrating agents, suspending agents, preservatives, buffers, wetting agents, and other excipients. Examples of filling agents are lactose monohydrate, lactose hydrous, and various starches; examples of binding agents are various celluloses, preferably low-substituted hydroxylpropyl cellulose, and cross-linked polyvinylpyrrolidone; an example of a disintegrating agent is croscarmellose sodium; and examples of lubricating agents are talc, magnesium stearate, stearic acid, and silica gel. Examples of suspending agents are hydroxypropyl cellulose, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose sodium, hydroxypropyl methylcellulose, acacia, alginic acid, carrageenin, and other hydrocolloides. Examples of preservatives, which control microbial contamination, are potassium sorbate, methylparaben, propylparaben, benzoic acid and its salts, other esters of parahydroxybenzoic acid such as butylparaben, alcohols such as ethyl or benzyl alcohol, phenolic compounds such as phenol, or quaternary compounds such as benzalkonium chloride.

For local injection via catheter at the site of PTCA, into the coronary artery lumen, similar formulations as above may be used. In addition, therapeutic molecules may be encapsulated in microparticles or nanoparticles, typically between lOOnm and lOOOnm in diameter, that serve to delay release of the molecules into the surrounding serum or tissue. In addition, microparticles or nanoparticles containing therapeutic molecules may be taken up by cells in the region of the target tissue, thus improving the efficiency of delivery and/or prolonging the availability of the therapeutic molecule. Examples of materials used to form microparticles or nanoparticles are poly lactic acid, poly(D,L-lactide-co-glycolide) (PLGA), liposomes, and dextran (Jiang et al, Adv Drug Deliv Rev, 57:391-410, 2005; BaIa et al, Crit Rev Ther Drug Carrier Syst, 21:387-422; Kayser et al, Curr Pharm Biotechnol, 6:3-5, 2005; U.S. Patent 6,805,879; U.S. Patent Application 20040191325).

For local delivery from stents or other implanted devices from which the flow of blood would carry eluted substances downstream to the target tissue, PMAMI can be mixed with polymers (co-dissolved or emulsified) and coated on such devices by spraying or dipping. The polymer is typically either bioabsorbable or biostable. A bioabsorbable

12 polymer breaks down in the body and is not present sufficiently long after implantation to cause an adverse local response. Bioabsorbable polymers are gradually absorbed or eliminated by the body by hydrolysis, metabolic process, bulk erosion, or surface erosion. Examples of bioabsorbable materials include but are not limited to polycaprolactone (PCL), poly-D, L-lactic acid (DL-PLA), poly-L-lactic acid (L-PLA), poly(lactide-co- glycolide), poly(hydroxybutyrate), poly(hydroxybutyrate-covalerate), polydioxanone, polyorthoester, polyanhydride, poly(glycolic acid), poly(glycolic acid-cotrimethylene carbonate), polyphosphoester, polyphosphoester urethane, poly (amino acids), cyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate), copoly(etheresters), polyalkylene oxalates, polyphosphazenes, polyiminocarbonates, and aliphatic polycarbonates. Biomolecules such as heparin, fibrin, fibrinogen, cellulose, starch, and collagen are typically also suitable. Examples of biostable polymers include parylene, polyurethane, polyethylene, polyethlyene teraphthalate, ethylene vinyl acetate, silicone and polyethylene oxide (PEO). Therapeutic molecules may also be coated on stents or other devices on which grooves, holes, a micropores or nanopores have been engineered into the surface, such that the formulation to be delivered is sequestered within the pores and released slowly into the lumen of the coronary artery after the device has been implanted.

EXAMPLE 1 Treatment of AMI in a Porcine Model Female or castrated male juvenile hybrid farm swine, 10-16 weeks old and weighing 35 +/- 10 kg, are utilized. Fasting is conducted prior to induction of anesthesia for device deployment, sample collection for serum chemistry and necropsy. Food, but not water, is withheld the morning of the procedure. To prevent or reduce the occurrence of thrombotic events, anti-platelet pharmacological therapy consisting of clopidogrel (75 mg per os [PO]) and acetylsalicylic acid (ASA; 325 mg, PO) is administered daily, with the exception of the implantation day, beginning at least 3 days prior to the scheduled procedure date.

Animals are tranquilized using intramuscular ketamine, azaperone or acepromazine and atropine. Anesthesia induction is achieved with propofol injected intravenously [IV] through a catheter in a peripheral ear vein. Upon induction of light anesthesia, the subject animal is intubated and supported with mechanical ventilation. Isoflurane (1 to 5.0% to effect by inhalation) in oxygen will be administered to maintain a surgical plane of

13 anesthesia. Prophylactic antibiotic duplocillin LA^® 0.05 ml/kg is given intramuscular [IM]. Intravenous fluid therapy is initiated and maintained throughout the procedure with saline (1 ml/kg/hour). The rate may be increased to replace blood loss or low systemic blood pressure.

The animal is placed in dorsal recumbency, and hair removed from access areas.

Animals are kept warm throughout the preparation and the procedure. Limb-leads are placed, and electrocardiography established. The access site is prepared with chlorexidine, 70% isopropyl alcohol and proviodine, and the area is appropriately draped to maintain a sterile field. After animal preparation, the femoral artery is accessed using a percutaneous approach. Alternatively, an incision will be made in the inguinal region to expose the femoral artery. An infiltration of bupivacain 0.5% (5 ml IM) on the femoral access site is performed to achieve local anesthesia and manage pain after surgery. A 7F or 8F- introducer arterial sheath is introduced and advanced into the artery. The sheath is connected to a pressure transducer for monitoring arterial pressure. An initial bolus of heparin (400 U/kg IV) is given and ACT performed approximately 5 minutes later. IfACT is under 300 seconds, an additional 100 to 400 U/kg of heparin is given. ACT is tested approximately every 20 minutes.

Under fluoroscopic guidance, a 7F guide catheter is inserted through the sheath and advanced to the appropriate location. After placement of the guide catheter, angiographic images of the coronary vessels are obtained with contrast media to identify the proper location for the deployment site. Quantitative angiography will be performed after injection of nitroglycerin 500 μg intracoronary [IC] to determine the appropriate vessel size for implantation and/or occlusion.

After visualization of the coronary artery anatomy, a segment of artery ranging from 2.6 mm to 3.5 mm mid-segment diameter is chosen, and a 0.014" guidewire will be inserted into the chosen artery. QCA is performed to accurately document the reference diameter for balloon angioplasty and/or stent placement.

Each stent delivery system or balloon catheter is prepared by applying vacuum to the balloon port; contrast/flush solution (50:50) is then introduced by releasing the vacuum. The appropriately sized balloon will be introduced into the appropriate artery by advancing the balloon catheter through the guide catheter and over the guidewire to the

14 deployment site. The balloon is then inflated at a steady rate to a pressure sufficient to target a balloon:artery ratio of 1.1:1 (acceptable range of about 1.05:1 to about 1.15:1) and held for 60 minutes. A contrast injection is performed during full inflation to demonstrate occlusion with the balloon. During occlusion, monitoring is performed for heart functions, and other monitoring parameters include isoflurane level, SaO₂, pulse rate, blood pressure, temperature, O₂ flow, and tidal volume. After the occlusion period, vacuum is applied to the inflation device in order to deflate the balloon. Complete balloon deflation is verified with fluoroscopy.

Immediately upon reperfusion, the test treatment is initiated. In one embodiment, a coated stent containing a therapeutic molecule is placed (target balloon:artery of about

1.15:1) in the same artery and region as the occlusion balloon. In a second embodiment, the therapeutic molecule is administered through the balloon catheter (or other injection catheter) into the region of the balloon occlusion. In a third embodiment, a drug delivery balloon is utilized to introduce the therapeutic molecule into the region of the balloon occlusion. Another embodiment administers a bolus injection via catheter and simultaneously provides the same, similar, or complementary therapeutic molecule in a stent coating, which elutes over a period of hours, days, or weeks.

Following completion of angiography, all catheters and sheaths are removed. If percutaneous access is achieved, pressure is applied to the access site until hemostasis is obtained. If a cutdown is performed, the femoral artery is ligated. The incision is closed in layers with appropriate suture materials.

The animals are placed in a pen and monitored during recovery from anesthesia for four to five hours following the procedure. Medical treatment including analgesia will be given as needed. Animals in apparent severe pain or distress, as determined by clinical observation and consultation with the facility veterinarian will be euthanized. ASA (325 mg/day PO) and clopidogrel (75 mg/day PO) are administered for the duration of the study. Moribidity/mortality checks and clinical observations are performed twice daily.

At the designated endpoint, typically 6 weeks post procedure, the animals are analyzed by MRI for LV function. Animals are then euthanized, the heart is excised, and the atria and great vessels are trimmed away. Next, the RV free wall is trimmed away from the LV (with septum intact). The LV is blotted dry, weighed and indexed by body weight

15 (in kg). The LV is sectioned transversely into five equal segments from apex to base, immersed in 10% buffered formalin, dehydrated at room temperature through ethanol series, and embedded in paraffin.

Serial 5-μm sections are prepared using a standard microtome. Sections are mounted and stained with hematoxylin and eosin (or trichrome) for determination of infarct size. Quantitative histological analyses are performed, and infarct size is determined

(Pfeffer et al, Circulation, 81:1161-1172, 1990). Infarct length is measured along the endo- and epicardial surfaces from each of the five LV segments (three sections per segment). Total LV circumference is measured along the endo- and epicardial surfaces from each of the five LV segments (three sections per segment). Infarct size is determined as percentage of total LV circumference. The ratio of scar length to body weight is calculated to exclude the potential influence of differences in body weight on infarct size.

Remodeling parameters. The maximum longitudinal dimension is measured before left ventricular sectioning. The LV is sectioned transversely into five equal segments from apex to base, and the maximum short-axis dimension after sectioning is measured. Outlines of the section rings and infarct scars are made on plastic overlays. "Thinning" ratio (ratio of average thickness of infarcted wall to average thickness of the normal wall) is measured by computerized planimetry. The maximum depth of infarct scar bulge in millimeters is measured on the contoured sections as an index of regional dilation. Bulging normalized to body weight is calculated. Ventricular volumes are computed from the short-axis areas and the long-axis length by the modified Simpson's rule, as used for echocardiographic studies during remodeling (Jugdutt et al, Circulation, 89:2297-2307, 1994).

The remaining sections are stained with Sirius red F3BA (0.1% solution in saturated aqueous picric acid) to discriminate between cardiomyocytes and collagen matrix (Wollert et al, Circulation, 95:1910-1917, 1997). Volume collagen fraction is calculated as the sum of all connective tissue areas divided by the total area of the image.

16 EXAMPLE 2 Delivery of Therapeutic Molecule From Microparticles and/or Coronary Stents

Therapeutic Dosage

Therapeutically effective amounts of a therapeutic molecule are administered via intra-arterial injection, intravenous injection, PTCA catheter, PTCA balloon, or indwelling device such as a stent. It is contemplated that the therapeutic molecule is administered using one or more of these methods, e.g. in a coating on a coronary stent and additionally injected through a PTCA catheter. Thus, in one embodiment, the therapeutic molecule is delivered both immediately by injection and over a prolonged period by elution from a stent. Alternatively, a therapeutically effective dose is administered solely by intra-arterial injection, but formulated in particles that in themselves deliver the therapeutic molecule over a prolonged period of time. Generally, the local drug delivery devices of this invention contain between about 0.001 mg and about 1.0 mg of a therapeutic molecule. Alternatively, intra-arterial or intravenous injection typically deliver between about 0.001 mg and about 10 mg of a therapeutic molecule. The exact dosage varies by disease severity, route of administration and the particular therapeutic molecule used.

Nanoparticle and Microparticle Formulation

The therapeutic agents disclosed herein may be formulated along with pharmaceutically acceptable carriers and/or polymers, e.g. polyglycolic acid (PGLA), polylactic acid (PLA), PGLA-PLA copolymers, polysaccharides, and/or phospholipids, as spherical particles with diameters of about 100 nm to about 1,000 nm. Such particles are referred to commonly and interchangeably as either microparticles and/or nanoparticles.

Many particles in this size range have the capability of entering living cells, and thus delivering the formulated therapeutic agent into cells of the target tissue. In such a system, delivery of the therapeutic agent is controlled in several ways: by the elution of the therapeutic agent via diffusion from the particle into the blood; by sequestration and subsequent release of the particles containing therapeutic agents in cells and extracellular matrix upstream of and in the target tissue; and by release of the therapeutic agent via biological breakdown, or degradation, of the particle itself. Details of such processes are described below ("Device Coatings").

17 Microparticles containing therapeutic agents may be produced by a variety of methods known in the art (Lemke and Hernandez-Trejo, Curr Pharm Biotechnol, 6:3-5, 2005), e.g. the emulsion-solvent evaporation technique (Sengupta et al, Nature, 436:568- 572, 2005) or the stable aqueous/aqueous emulsion system (U.S. Patent 6,805,879). Different techniques are chosen based on the chemical, electrical, and hydrophobic properties of a given therapeutic agent. Microparticles are administered by themselves suspended in an appropriate solvent/buffer system (Jiang et al, Adv Drug Deliv Rev, 10:391-410, 2005), by intra-arterial injection (Guzman et al, Circulation, 94:1441-1448, 1996), by PTCA balloon delivery (Kaul et al, Circulation, 107:2551-2554, 2003), or any suitable method. Alternatively, microparticles are incorporated into a device coating such as those described herein. Microparticles themselves may incorporate more than one layer, with each layer possessing unique characteristics with regard to formulation and delivery of therapeutic agents.

Any suitable microparticle known in the art may be used to encapsulate the therapeutic molecules in accordance with this disclosure. Stable aqueous/aqueous emulsion systems, such as those described in U.S. Patent 6,805,879, are particularly useful for microparticle formulations. The basis of this system is the selection of two aqueous polymer solutions (a dispersed polymer solution and a continuous polymer solution) that are immiscible with each other, and, optionally, a surface modifier that is charged and relatively immiscible with the first two. The dispersed polymer solution is dispersed as microparticles within the continuous polymer solution by mixing under conditions of high shear stress. The amount shear stress controls the size of the microparticles. The surface modifier is added in low amounts relative to the first two in order that it becomes enriched in at the surface of the microparticles formed by the dispersed polymer solution. The charged nature of the surface modifier prevents aggregation of the microparticles. In a useful embodiment, the microparticles are lyophilized for preservation and storage. Therapeutic solutions and device coatings are made from the lyophilized micropaticles. Hydrophilic polymers useful for the continuous and/or dispersed phases include, for example, dextran (MW 100,000 - 1,000,000), PEG, PEG/PLGA mixtures, and sodium alginate. Useful surface modifiers include, for example, phospholipids.

18 Device Coatings

The therapeutic molecules used in accordance with the principles of this disclosure are associated with the implantable device by suitable methods known in the art. In some embodiments, the therapeutic molecules are attached to the device by way of a polymeric coating having known and controllable release characteristics, being biocompatible when implanted in animals and humans, and being non-thrombogenic when in contact with blood and the vascular system. For example and as discussed herein, the reactants and reaction conditions used to generate the polymer compositions disclosed herein may be modified to alter the properties of the final polymer composition. For example, properties such as the diffusion coefficients (e.g., the rate at which the therapeutic molecules are able to diffuse through the polymer matrix), the rate of degradation of one or more of the polymer components, and the rate of the release of the therapeutic molecules are manipulated by altering the reaction conditions and reagents, and hence the final polymer properties, used to generate the coating polymers.

Two major classes of polymeric coatings may be used with implantable devices: biostable (non-erodable) coatings; and bioabsorbable (biodegradable) coatings. Examples of biostable coatings are fluorosilicone, silicone co-polymers, polyethylene glycol (PEG), ρoly(butyl methacrylate), poly(ethylene-co-vinyl acetate), polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, polyhydroxyethyl methacrylate, polyethylene oxide. Examples of bioabsorbable coatings are polyglycolic acid (PGLA), polylactic acid (PLA), PGLA-PLA copolymers, polysaccharides, and phospholipids. In addition, therapeutic agents may be applied directly to implantable devices without polymeric carriers, where the surface of the device is equipped with holes, crevices, micropores, or channels in which the therapeutic agents are sequestered to varying degrees, thus allowing controlled release in vivo.

Delivery of therapeutic molecules from biostable coatings occurs via diffusion from the surface and/or interior of the coating into surrounding tissue, interstitial space, or vascular lumen. For bioabsorbable coatings, in vivo hydrolytic degradation of the polymeric coating is an additional mechanism for release of the therapeutic agent, whereby metabolism of the polymeric coating by endogenous enzymes may also play a role

19 (Meyers et al., J. Med. Chem. 2000, 43, 4319-4327). Important factors influencing hydrolytic degradation include water permeability, chemical structure, molecular weight, morphology, glass transition temperature, additives, and other environmental factors such as pH, ionic strength, site of implantation, etc. The duration of sustained delivery can be adjusted from few days up to one year by a person of ordinary skill in the art through proper selection of polymer and fabrication method.

In one embodiment, preparation of coated implantable devices is accomplished by dissolving the dried polymer in a suitable solvent and spin-coating, dipping, or spraying the medical device, typically using, for example, a 5 wt % in 2-propanol solution of the polymer. The selection of other suitable solvents for coating the medical devices will typically depend on the particular polymer as well as the volatility of the solvent.

One method of modulating the properties of the polymer compositions is to control the diffusion coefficient of the one or more polymer coating layers. The diffusion coefficient relates to the rate at which a compound diffuses through a coating matrix. Methods for determining diffusion coefficients are described, for example, in U.S. Patent

Nos. 5,786,439 and 5,777,060.

One method for coating a local delivery device includes sequentially applying a plurality of relatively thin outer layers of a coating composition comprising a solvent mixture of polymeric silicone material, a crosslinking agent, and one or more of the therapeutic agents (see, for example, U.S. Patent No. 6,358,556). The polymeric coatings are cured in situ and the coated, cured prosthesis is sterilized in a step that includes pretreatment with argon gas plasma and exposure to gamma radiation, electron beam, ethylene oxide, and/or steam.

In another embodiment, the polymeric coating is applied as a mixture, solution or suspension of polymeric material and one or more of the therapeutic molecules is dispersed in an organic vehicle or a solution or partial solution of such agents in a solvent or vehicle for the polymer and/or the therapeutic molecules. Optionally the various therapeutic agents are placed within different polymer layers. The therapeutic molecules are dispersed in a carrier material which is variously the polymer, a solvent, or both. In some instances, the coating is applied sequentially in one or more relatively thin layers. In some applications the coating is further characterized as an undercoat and a topcoat. The coating thickness

20 ratio of the topcoat to the undercoat varies with the desired effect and/or the elution system. In an illustrative embodiment of a device having a plurality of coating layers, the coating on the medical device includes one or more base coatings and a top coating (see, for example, U.S. Patent No. 6,287,285).

In another embodiment, linking agents are used to encapsulate and/or link the therapeutic molecule to the polymer matrix or link the various components of the polymer matrix together (e.g., the different polymers that comprise the various coating layers, the bioactive agents in the polymer matrices etc.). Such linking agents include, for example, polyester amide (PEA), polyethylene imine (PEI), avidin-biotin complexes, photolinking, functionalized liposomes, microsponges and microspheres.

In another embodiment, therapeutic molecules are modified by chemically linking them to a high molecular weight, water-soluble polymer carrier. This modified therapeutic molecule is termed herein an agent-polymer conjugate. The agent-polymer conjugate is that the chemical linkage of the agent to the water-soluble polymer can be manipulated to hydro lytically degrade, thereby releasing biologically active agent into the environment in which they are placed.

The agent-polymer conjugate is incorporated into a controlled release matrix, formulated from a second biocompatible polymer. When implanted into a tissue such as the arterial lumen, the controlled-release matrix releases the agent-polymer conjugate which further releases free agent (therapeutic) molecules to treat the area of the tissue in the immediate vicinity of the polymer. The agent-polymer conjugates also diffuses within the tissue. As the agent conjugates diffuse, in blood or tissue, the bond between the polymer and the agent degrades in a controlled pattern, releasing the active agent.

There are several other variables, that may be controlled to produce a final product that is best suited for treating a certain disease with specific kinds of agents. A first variable is the size and characteristics of the water-soluble polymer carrier. Either synthetic or naturally occurring polymers may be used. While not limited to this group, some types of useful polymers include are polysaccharides (e.g., dextran and ficoll), proteins (e.g., poly-lysine), poly(ethylene glycol), and poly(methacrylates). Different polymers produce different diffusion characteristics in the target tissue or organ as a result of their different size and shape.

21 The rate of hydrolytic degradation, and thus of agent release, may be altered from minutes to months by altering the physico-chemical properties of the bonds between the agents and the polymer. While not wishing to be limited to the following types of bonds, artisans can bond therapeutic agents to water-soluble polymers using covalent bonds, such 5 as ester, amide, amidoester, and urethane bonds. Ionic conjugates are also used. By changing the nature of the chemical association between water-soluble polymer and agent, the half-life of carrier-agent association is varied. This half-life of the agent-polymer conjugate in the environment in which it is placed determines the rate of active agent release from the polymer and, therefore, the degree of penetration that the agent-polymer 10 conjugate can achieve in the target tissue. Other suitable hydrolytically labile bonds which can be used to link the agent to the water soluble polymer include thioester, acid anhydride, carbamide, carbonate, semicarbazone, hydrazone, oxime, iminocarbonate, phosphoester, phophazene, and anhydride bonds.

The rate of release is also affected by (a) stereochemical control (varying amounts

15 of steric hindrance around the hydrolyzable bonds); (b) electronic control (varying electron donating/accepting groups around the reactive bond, controlling reactivity by induction/resonance); (c) varying the hydrophilicity/hydrophobicity of any optional spacer groups between the therapeutic agent and the polymer; (d) varying the length of the optional spacer groups (increasing length making the bond to be hydrolyzed more

20 accessible to water); and (e) using bonds susceptible to cleavage by soluble blood plasma enzymes.

The properties of the controlled release matrix vary the rate of polymeric agent conjugate release into the tissue (Dang, et al., Biotechnol. Prog., 8: 527-532, 1992; Powell, et al., Brain Res., 515: 309-311, 1990; Radomsky, et al., Biol, of Repro., 47: 133-140,

25 1992; Saltzman, et al., Biophys. J, 55: 163-171, 1989; Chemical Engineering Science, 46: 2429-2444, 1991; J. Appl. Polymer ScL, 48: 1493-1500, 1992; Sherwood, et al., BioTechnology, 10: 1446-1449, 1992). Among the variables which affect conjugate release kinetics are: controlled release polymer composition, mass fraction of agent- polymer conjugate within the matrix (increasing mass fraction increases release rate),

30 particle size of agent-polymer conjugate within the matrix (increasing particle size increases release rate), composition of polymeric agent conjugate particles, and polymer size (increasing surface area increases the release rate), and polymer shape of the

22 controlled release matrix. Suitable polymer components for use as controlled-release matrices include poly(ethylene-co-vinyl acetate), poly(DL-lactide), polyglycolide, copolymers of lactide and glycolide, and polyanhydride copolymers.

As discussed in U.S. Pat. No. 6,300,458, hydroxypolycarbonates (HPC) are used as hydroxyl functional polymers that bind therapeutic agents or carbohydrate polymers chemically or via hydrogen bonding. These copolymers have properties attractive to the biomedical area as is or by conversion to the HPC product provided by hydrolysis or by in vivo enzymatic attack. A feature of these polymers is their tendency to undergo surface erosion. Heterogeneous hydrolysis theoretically would better preserve the mechanical strength and physical integrity of the matrix during biodegradation, which is highly desirable in terms of predictable performance. To maximize control over the release process, it is desirable to have a polymeric system which degrades from the surface and deters the permeation of the agent molecules. Achieving such a heterogeneous degradation requires the rate of hydrolytic degradation on the surface to be much faster than the rate of water penetration into the bulk.

As noted above, the polymer compositions disclosed herein allow for the controlled release of therapeutic agents. This controlled release is modulated by the pH of the environment in which the polymer compositions function. In this context, one embodiment includes the controlled release of the therapeutic agents from a hydrophobic, pH-sensitive polymer matrix (see, for example, U.S. Patent No. 6,306,422). A polymer of hydrophobic and weakly acidic comonomers is used in the controlled release system. Weakly basic comonomers are used and the active agent is released as the pH drops. For example, a pH- sensitive polymer releases the therapeutic agents when exposed to a higher pH environment as the polymer gel swells. Such release can be made slow enough so that the therapeutic agent remains at significant levels for a clinically useful period of time.

Related embodiments provide additional compositions for releasing therapeutic agents using a dual phase polymeric agent-delivery composition. These dual phase polymeric compositions comprise a continuous biocompatible gel phase, a discontinuous particulate phase comprising defined microparticles, and the therapeutic agents to be delivered (see, for example, U.S. Patent No. 6,287,588). Typically in such embodiments, a microparticle containing a therapeutic agent is entrained within a biocompatible polymeric

23 gel matrix. The therapeutic agent release is contained in the microparticle phase alone or in both the microparticles and the gel matrix. The release of the therapeutic agent is prolonged oγer a period of time, and the delivery is modulated and/or controlled. In addition, the second agent is loaded in the same or different microparticles and/or in the gel matrix. Alternatively, layered microparticles (or nanoparticles) may be produced in which, for example, the inner core consists of a particular polymer carrying the therapeutic agent while an outer layer consisting of the same or a different material may either carry the therapeutic agent and release it with different release kinetics (Sengupta et al, Nature, 436:568-572, 2005), or not carry the therapeutic agent and serve to control its release from the inner core.

Drug-eluting devices of this invention release therapeutic agents. These agents are released at a constant rate or at a multi-phasic rate. For example, in one embodiment, the release comprises an initial burst (immediate release) of the therapeutic agents present at or near the surface of the coating layer, a second phase during which the release rate is slower or sometimes no therapeutic agent is released, and a third phase during which most of the remainder of the therapeutic agents is released as erosion proceeds.

All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

What is claimed is:

24

Claims

1. An implantable device comprising a therapeutic molecule encapsulated in a microparticle, wherein said therapeutic molecule is selected from the group consisting of an estrogen, a prostaglandin EP₃ receptor agonist, a caspase inhibitor, a potassium channel opener, a nitric oxide donor, an aldosterone receptor antagonist, an inhibitor of platelet- endothelial cell adhesion molecules, IL-6/sIL-6R, IL-6, a GP130 agonist, an IL-18 antagonist, a glycosaminoglycan analog, a plasminogen activator inhibitor- 1 antagonist, relaxin, clusterin, p38 MAP kinase inhibitor, a cardiac regeneration factor, insulin-like growth factor 1 (IGF-I), hepatocyte growth factor (HGF), growth-differentiation factor- 15 (GDF-15), hypoxia inducible factor- 1 (HIF-I), a TNF-α inhibitor, a CD-147 inhibitor, a PDGF agonist, and a neutrophil gelatinase-associated lipocalin (NGAL) inhibitor.

2. The implantable device of claim 1, wherein said device is a stent.

3. The implantable device of any of claims 1-2, wherein said microparticle is a liposome.

4. The implantable device of any of claims 1-2, wherein said microparticle is a polymeric microsphere.

5. The implantable device of claim 4, wherein said polymeric microsphere is produced using an aqueous/aqueous emulsion system.

6. The implantable device of claim 4, wherein said polymeric microsphere comprises dextran, PEG, or PLGA.

7. The implantable device of any of claims 1-6, wherein said therapeutic molecule is 17β-estradiol.

8. The use of the implantable device of any of claims 1 -7 for the treatment of a cardiac disorder.

9. The use of claim 8, wherein said cardiac disorder is selected from the group consisting of acute myocardial infarction, a chronic ischemic condition, reperfusion injury, chronic heart disease, and cardiac fibrosis.

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10. The use of a therapeutic molecule encapsulated in a microparticle for the treatment of a cardiac disorder, wherein said therapeutic molecule is selected from the group consisting of an estrogen, a prostaglandin EP₃ receptor agonist, a caspase inhibitor, a potassium channel opener, a nitric oxide donor, an aldosterone receptor antagonist, an inhibitor of platelet-endothelial cell adhesion molecules, IL-6/sIL-6R, IL-6, a GP 130 agonist, an IL- 18 antagonist, a glycosaminoglycan analog, a plasminogen activator inhibitor- 1 antagonist, relaxin, clusterin, p38 MAP kinase inhibitor, a cardiac regeneration factor, insulin-like growth factor 1 (IGF-I), hepatocyte growth factor (HGF), growth- differentiation factor- 15 (GDF-15), hypoxia inducible factor- 1 (HIF-I), a TNF-α inhibitor, a CD- 147 inhibitor, a PDGF agonist, and a neutrophil gelatinase-associated lipocalin (NGAL) inhibitor.

11. The use of claim 10, wherein said therapeutic molecule is 17β-estradiol.

12. The use of any of claims 10-11, wherein said cardiac disorder is selected from the group consisting of acute myocardial infarction, a chronic ischemic condition, reperfusion injury, chronic heart disease, and cardiac fibrosis.

13. The use of any of claims 10-11, wherein said cardiac disorder is acute myocardial infarction.

14. The use of any of claims 10-13, wherein said therapeutic molecule is administered by intravenous or intra-arterial injection.

15. The use of any of claims 10-13, wherein said molecule is administered during percutaneous transluminal coronary angioplasty.

16. The use of claim 15, wherein said molecule is administered using a drug delivery percutaneous transluminal coronary angioplasty balloon.

17. The use of any of claims 10-13, wherein said molecule is administered using an implantable intra-arterial stent.

18. The use of any of claims 10-17, wherein said microparticle is a liposome.

19. The use of any of claims 10-17, wherein said microparticle is a polymeric microsphere.

26

20. The use of claim 19, wherein said polymeric microsphere is produced using an aqueous/aqueous emulsion system.

21. The use of claim 19, wherein said polymeric microsphere comprises dextran, PEG, or PLGA.

22. A method for treating a cardiac disorder comprising administering a therapeutic molecule encapsulated in a microparticle, wherein said therapeutic molecule is selected from the group consisting of an estrogen, a prostaglandin EP₃ receptor agonist, a caspase inhibitor, a potassium channel opener, a nitric oxide donor, an aldosterone receptor antagonist, an inhibitor of platelet-endόthelial cell adhesion molecules, IL-6/sIL-6R, IL-6, a GP 130 agonist, an IL- 18 antagonist, a glycosaminoglycan analog, a plasminogen activator inhibitor- 1 antagonist, relaxin, clusterin, ρ38 MAP kinase inhibitor, a cardiac regeneration factor, insulin-like growth factor 1 (IGF-I), hepatocyte growth factor (HGF), growth-differentiation factor- 15 (GDF- 15), hypoxia inducible factor- 1 (HIF-I), a TNF-α inhibitor, a CD- 147 inhibitor, a PDGF agonist, and a neutrophil gelatinase-associated lipocalin (NGAL) inhibitor.

23. The method of claim 22, wherein said therapeutic molecule is 17β-estradiol.

24. The method of any of claims 22-23, wherein said cardiac disorder is selected from the group consisting of acute myocardial infarction, a chronic ischemic condition, reperfusion injury, chronic heart disease, and cardiac fibrosis.

25. The method of any of claims 22-23, wherein said cardiac disorder is acute myocardial infarction.

26. The method of any of claims 22-25, wherein said therapeutic molecule is administered by intravenous or intra-arterial injection.

27. The method of any of claims 22-25, wherein said molecule is administered during percutaneous transluminal coronary angioplasty.

28. The method of claim 27, wherein said molecule is administered using a drag delivery percutaneous transluminal coronary angioplasty balloon.

27

29. The method of any of claims 22-25, wherein said molecule is administered using an implantable intra-arterial stent.

30. The method of any of claims 22-29, wherein said microparticle is a liposome.

31. The method of any of claims 22-29, wherein said microparticle is a polymeric microsphere.

32. The method of claim 31, wherein said polymeric microsphere is produced using an aqueous/aqueous emulsion system.

33. The method of claim 31, wherein said polymeric microsphere comprises dextran, PEG, or PLGA.

28