HOLDER FOR CELL CULTURE DEVICES
FIELD OF THE INVENTION
The invention relates generally to the packaging, handling, and storage of cell culture devices; and more particularly to a holder for cell culture devices.
BACKGROUND OF THE INVENTION
Recently, a new cell culture apparatus has been developed which promotes even distribution of anchorage dependent cells, spatial efficiency, versatility, and conditions which can permit a high rate of cell growth in achieving a high cell density (U.S. application 09/526,006, the disclosure of which is herein incorporated by reference, and assigned to the same assignee) . In one preferred embodiment, the cell culture apparatus is comprised of a frame to which is contacted and secured taut thereto, in a leak- proof sealing arrangement, two membranes. The chamber of the cell culture apparatus, formed by the frame and mem- branes, is accessed by at least one aperture. The at least one aperture serves as an access port by which substances (e.g., cells and/or tissue culture growth medium) can be introduced into, or withdrawn from, the chamber. In a preferred embodiment, the at least one aperture is sealed by a "septum" which comprises a gasket material that fills all or a substantial portion of the aperture, and which is sufficiently pliable to be self-sealing; e.g., thereby allowing for penetration by a needle, and resealing after needle withdrawal. In the tissue culture industry, a cell culture vessel is subjected to various handling requirements throughout the stages of use. Presently, a cell culture vessel, such as a tissue culture flask or a tissue culture dish, is handled individually. More specifically, traditional cell culture
technique is to remove a flask of interest from a cell culture incubator, carry the flask to a laminar flow hood, perform the desired task (e.g., splitting of the cell culture, or feeding the cell culture, or sampling from the cell culture) in the aseptic environment provided by the hood, returning the flask to the incubator, and placing the flask on a shelf in the incubator for storage. Such individual handling requirements present a bottleneck in terms of efficient handling, processing, and storage of cell cultures. As noted by those skilled in the art in a recently published report of the state of the art of cell culture, "Cell culture labs need better technical solutions in order to handle more cell lines and analyze more proteins" .
Thus, there is a need for devices which facilitate handling and storage of multiple cell culture devices; and more particularly, to a holder adapted to receive a plurality of cell culture devices. Further, there is a need for a holder that allows easy access to a plurality of cell culture devices stored therein, while also preventing the cell culture devices from sliding out of the holder without substantially impairing the removal of the cell culture devices by a user.
SUMMARY OF THE INVENTION It is an objective of the present invention to provide a holder for cell culture devices which can function as a container during one or more functions comprising handling one or more cell culture devices during cell culture technique, and storing one or more cell culture devices (before use or during an incubation process) .
Another objective of the invention is to provide a holder which can be used as a storage system for a plurality
of cell culture devices, and which facilitates handling the plurality of cell culture devices.
Another objective of the invention is to provide a holder which offers good storage efficiency for a plurality of cell culture devices.
Another objective of the invention is to provide a holder comprising an organizer that provides easy access to, and easy viewing of, cell culture devices stored therein. A still further objective of the invention is to provide such a holder which, when filled with one or a plurality of cell culture devices, prevents the cell culture devices contained therein from sliding out of the holder without substantially impairing the removal by a user of the cell culture devices contained therein. These and other objects and advantages of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings in which corresponding parts are identified by the same reference numerals in several views, and with the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a holder according to an embodiment of the present invention. FIG. 2 is a front perspective view of a holder according to an embodiment of the present invention.
FIG. 3 is a cross-sectional side view of a holder according to an embodiment of the present invention.
FIG. 4 is an elevational view of a holder completely filled with cell culture devices in forming a multi-pack.
FIG. 5 is a front perspective view of a holder partially filled with cell culture devices.
FIG. 6 is a front view of a holder according to another embodiment of the present invention.
FIG. 7 is a front perspective view of another embodiment of the holder partially filled with cell culture devices. FIG. 8 is a front view of a holder filled with cell culture devices .
FIG. 9 is a cross-sectional side view of the holder taken along line 2-2 of FIG. 8.
FIG. 10 is a front view of a plurality of holders which have been stacked and interlocked together to form an assembled unit of a plurality of interlocked holders.
DETAILED DESCRIPTION OF THE INVENTION
Provided is a holder for the cell culture devices, wherein the term "cell culture device" is used herein for purposes of the specification and claims to mean a cell culture device with the following preferred characteristics. The cell culture device comprises a frame; at least one gas permeable membrane, and preferably two membranes, extended and stretched taut over and securedly sealed to the frame in forming a culture chamber; and at least one resealable aperture through the frame which allows substances to be introduced into, or withdrawn from, the culture chamber. Alternatively, the frame may comprise a gas permeable membrane on one side, and an opposite side comprises a hard plastic surface typical of standard tissue culture containers. In a preferred embodiment, the cell culture device comprises a frame over which is extended and securedly sealed thereto two gas permeable membranes in forming at least one culture chamber therebetween. The frame is sufficiently rigid to provide a housing for assembling the cell culture device. The at least one gas permeable membrane is of suitable thickness to provide sufficient gas permeability to accom-
modate cell growth in the chamber, and to provide sufficient structural integrity for handling the apparatus. Further, the one or more membranes are of a sufficient optical transparency and clarity so as to observe during culture, the color of the tissue culture medium, and cellular characteristics (e.g., growth and morphology of cells such as by microscopy) . The frame has at least one resealable aperture, and preferably at least two resealable apertures, which allows substances to be introduced into, or withdrawn from, the culture chamber. Each aperture of the frame may serve as a passageway into which is guided a portion of an instrument (e.g., needle or pipette or pipette tip) for introducing a substance into or withdrawing a substance from the culture chamber. The dimensions of the cell culture device may depend on one or more factors including, but not limited to, the desired fluid capacity of the culture chamber formed therewith, and the dimensions of the culture chamber. In a preferred embodiment, the cell culture is generally rectangular in shape, and comprises a dimension sufficient to be accommodated, and be substantially held in position, by a standard mechanical stage specimen holder (e.g., that accommodates a 96 well microtiter plate) of a microscope. In a more preferred embodiment, the cell culture device has a length in a range of from about 10 cm to about 13.5 cm, a width in a range of from about 7 cm to about 9 cm, and a height in a range of from about 0.2 cm to about 1.0 cm. In a most preferred embodiment, the cell culture device has a length of about 12.7 cm, a width of about 8.5 cm, and a height of about 0.58 cm. Now referring to the drawings in general, it is apparent that holder 10 for the aforementioned cell culture devices in accordance with the present invention generally comprises a housing. The detailed relationship between the
individual features of the holder is not critical to the invention, insofar as to whether they be manufactured as separate components which are then assembled into the unit comprising the holder or as an integral one-piece unit such as by a molding process. Therefore, it is apparent to one skilled in the art that the holder according to the present invention may be fabricated with methods now known in the art, or later devised, without departing from the spirit or scope of the invention. Additionally, the holder may be formed from a material which provides the requisite rigidity and support for holding a plurality of cell culture devices therein in typical conditions encountered in storage, shipping, and handling. As the specific character of the material does not in and of itself constitute the subject matter of the present invention, it should be apparent to those skilled in the art that a wide latitude of choice may be exercised in selecting a material suitable for formation and/or fabrication of holder 10. In a preferred embodiment, holder 10 may be generally molded from synthetic resinous material, such as plastic; and in a more preferred embodiment, the material comprises polyethylene or polypropylene.
Depending on the material used for its composition, the holder may be transparent, or translucent (semi-transparent) , or opaque. It is generally known that prolonged exposure of cultured cells to light typically illuminating laboratory environments in which cell culture procedures are performed ("room light") adversely affects cell properties and/or cell function. In a preferred embodiment, the holder prevents the transmission of room light, in the visible range of from about 550 nm to about 700 nm, through the holder into the interior of the holder in which one or more cell culture devices is or can be stored. In this preferred embodiment, the material of which the holder is comprised is
selected from the group consisting of an opaque material, or a material colored to filter room light in the visible range of from about 550 nm to about 700 nm away from the holder. When the material is colored to filter away the room light in the visible range of from about 550 nm to about 700 nm, a preferred color is selected from the group consisting of blue, green, and a combination thereof. It is apparent that the desired coloring can be achieved by adding a dye to the synthetic resin in a process of molding the holder, or can be later applied on the exterior surface of the holder as a paint or coating.
In a further embodiment, the holder further comprises an identification code. An identification code comprises an identifier placed on or made a part of a holder, and which may include, but is not limited to, a bar code, a number, a series of numbers, a color, a series of colors, a letter, a series of letters, a symbol, a series of symbols, and a combination thereof. Thus, for example, when a plurality of holders are used together, and each holder has an identifi- cation code that distinguishes it from other holders in the plurality, an identification code may be used for one or more of tracking, locating, identifying, identifying the position of (e.g., as relative to a point of origin), and cataloging the holder having that identification code which is sought to be identified. Encoding individual holders with a unique identification code per holder is particularly useful for an assembled unit comprising a plurality of holders which are interlocked together, as will be apparent from descriptions to follow. While the identification code can be placed anywhere on the holder, preferably the identification code is placed on one or more holder surfaces such as the top, or bottom, or side wall, or back wall, or a combination thereof. It will be apparent to one skilled in
the art that the identification code can be applied to the holder by a means that includes, but is not limited to, a sticker, ink printing, laser printing, laser engraving, etching, or other suitable means for applying the identifi- cation code to the holder; or may be made apart of the holder by a means that includes, but is not limited to, molding the identification code as part of the holder, or other suitable means for making the identification code part of the holder. Holder 10 is shown to have a pair of opposing side walls 12a and 12b which define a chamber therebetween; a wall 14 that, when holder 10 is positioned in a spatial orientation such as illustrated in FIGs . 1-3 and 6-10, may serve as a base; a wall 16 that, when holder 10 is posi- tioned in a spatial orientation such as illustrated in FIG. 1-3 and 6-10, may serve as a top wall; a back wall 18; and an open front 20, defined by front edges of the side walls 12a and 12b, through which is inserted one or a plurality of cell culture devices 40 and into the chamber defined by the pair of side walls. In a preferred embodiment, the pair of parallel-spaced apart side walls 12a and 12b, and walls 14, 16, and 18, are formed as an integral one-piece unit such as by an injection molding process. Alternatively, walls 12a, 12b, 14, 16, and 18 may each be separately manufactured, and assembled using one or more methods known in the art such as by a snap-fit arrangement, gluing with an adhesive, and securing with fastener means (e.g., screws). In the illustrated embodiments, holder 10 is shown to be dimensioned for receiving and accommodating a maximum of 20 cell culture devices, but it is apparent to one skilled in the art that holder 10 may be dimensioned to receive a larger or smaller maximum number of cell culture devices. As illustrative, non-limiting examples, holder 10 may be dimensioned to
accommodate a maximum of cell culture devices, wherein the maximum is a number in the range of from about 10 to about 50 cell culture devices. In light of a preferred embodiment in which the cell culture device has a length of about 12.7 cm and a width of about 8.5 cm and a height of about
0.58 cm, a preferred embodiment of a holder according to the present invention for accommodating 20 cell culture devices comprises the following dimensions when positioned as appearing in FIGs . 1 & 6 : a height of about 17 to about 17.5 cm; a width of about 13.5 to about 13.9 cm; and a depth of about 7.2 to about 9 cm.
In accordance with the invention, and shown in the illustrated embodiments and particularly in FIGs. 1 & 6-7, side walls 12a and 12b each comprise a plurality of paral- lei, spaced apart channels 22 extending thereacross from opening 20 to back wall 18. The plurality of channels 22 form inwardly-directed ledges 32, located approximately midway between channels 22 in the side walls, within holder 10 which are spaced apart between, and extend generally paral- lei to, walls 14 and 16 for slidably receiving and guiding cell culture devices into holder 10 (see also, FIGs. 2, 5, 7-8). As illustrated in FIGs. 1, 2, & 5-8, a channel 22 with its adjacent ledges 32, provide a space and shelf (ledge) for receiving a single cell culture device therein. As shown in FIGs. 1, 2 & 5-8, the vertical distance of the space comprising channel 22 (e.g., the space formed by and between two vertically adjacent ledges 32) is approximately equal to but greater than the thickness of cell culture device 40. This enables a cell culture device to be slid easily into channel 22, while being guided by two vertically adjacent ledges 32, and along at least one of the two adjacent ledges 32 in retaining cell culture device 40
therein in a secured position (as shown in FIGs. 3-5 & 7- 10) .
The distance between walls 12a & 12b provide a tolerance, and the spaces comprising channels 22 provide a toler- ance, for ease of slidably receiving cell culture devices. For example, in a preferred embodiment wherein the thickness of the cell culture device 40 comprises 5.8 mm, the space between two vertically adjacent ledges 32 which receives cell culture device 40 comprises a vertical distance greater than 5.8 mm in accordance with the necessary tolerance for ease of slidably receiving cell culture devices into the channel. Such final tolerances for ease of slidably receiving cell culture devices into such channels may depend on factors including, but not limited to, the process of manu- facture (e.g., the limits of the injection molding process), the nature of the material comprising the holder, and the nature of the material comprising the frame (or portion thereof) of the cell culture device which contacts the one or more ledges . In a preferred embodiment of the holder according to the present invention, provided is a locking means which is adapted to slidably engage a cell culture device in preventing the cell culture device from sliding out of the holder without substantially impairing the removal of the cell cul- ture device from the holder by a user. In one embodiment of this feature, as illustrated in FIGs. 1-5, the space comprising channel 22 progressively varies decreasingly in vertical distance from a widest point at the initial opening of the channel (i.e., at open front 20) to a narrowest point at the opposite end of the channel (i.e., point closest to wall 18) . For example, the vertical distance between two vertically adjacent ledges 32, along which is slid cell culture device 40, is greater than the vertical distance between the
same two ledges at the point closest to wall 18. Such an arrangement provides more of a tolerance for when the cell culture device is initially inserted into channel 22 in starting the process of slidably receiving the cell culture device along the adjacent ledges. As the cell culture device is pushed further along the ledges and directionally towards wall 18, the tolerance decreases, thereby causing the adjacent ledges, at a point closest to wall 18, to contact and engage the cell culture device in a more secure manner than at the initial point of insertion of the cell culture device. Thus, the locking means comprises the portion of the adjacent ledges which contacts and engages the cell culture device in a friction fit that prevents the engaged cell culture device from sliding out of the holder, but does not prevent the cell culture device from being removed from the holder by a user whom grasps the cell culture device (e.g., by the portion which protrudes from the opening of the holder) and pulls it towards the opening of the holder to disengage it from the locking means in removing the cell culture device from the holder. In continuing with the illustrative example of the cell culture device having a thickness of about 5.8 mm, the space comprising channel 22 at the initial opening of the channel (i.e., at open front 20) may be selected from a range of about 6.8 mm to about 8.2 mm, after which it progressively decreases to a vertical distance (at a point closest to wall 18) which may be selected from a range of about 6.1 mm to about 6.7 and which engages the cell culture device in a friction fit. There are various methods to achieve the progressively decreasing vertical distance between two adjacent ledges. For example, as illustrated in FIGs. 2 & 5 ledge 32, along which is slid the cell culture device 40, may be beveled such that a greater vertical distance is
provided by the ledge 32 at point 32a (e.g., at open front 20) as compared to the vertical distance at point 32b (e.g., closest to wall 18 or defined by a ridge comprising a stop) . In another embodiment of the locking feature, a locking means comprises a mating protrusion, and the holder comprises a plurality of locking means. Thus, the holder comprises a plurality of mating protrusions, wherein each mating protrusion is adapted to slidably engage a cell culture device and hold the engaged cell culture device, in a fric- tion fit, in preventing the cell culture device from sliding out of the holder without substantially impairing the removal of the cell culture device from the holder by a user. For example, as illustrated in FIGs. 6, 7, & 9, each mating protrusion 50 further comprises a retaining rib 52 which engages a cell culture device 40 in holding the cell culture device in the holder. In a more preferred embodiment, as illustrated in FIGs. 6-7, the plurality of parallel-spaced apart mating protrusions alternate in a zig-zag configuration, wherein the spacing between two adjacent, alternating mating protrusions is slightly larger than the height of a cell culture device. In continuing with this preferred embodiment, and as illustrated in FIGs. 7 & 9, cell culture device 40 contains bevel 55. Thus, mating protrusion 50 should be sufficiently flexible so as to be displaced slightly when the mating protrusion is in contact with a cell culture device so that retaining rib 52 can then fit over and engage bevel 55 of the cell culture device in holding the cell culture device in the holder by a friction fit. When a user desires to remove the cell culture device from the holder, the user grasps the cell culture device (e.g., by the portion which protrudes from the opening of the holder) and pulls it towards the opening of the holder. The pulling action causes the mating protrusion to displace
slightly in disengaging both the mating protrusion and the retaining rib from the cell culture device, in allowing the cell culture device to be slid smoothly on and along the one or more ledge 32 with which it is in contact, and in remov- ing the cell culture device from the holder. Such an arrangement of locking means prevents a cell culture device from sliding out of the holder unintentionally, without substantially impairing the removal of the cell culture device from the holder by a user. As illustrated in FIGs. 6-8, two adjacent mating protrusions may preferably alternate as to the direction in which their respective retaining rib projects. For example, as shown in FIGs. 7 & 8, mating protrusion 50a has a retaining rib which projects upwards (e.g., in the direction of wall 16), thus engaging a cell culture device 40 along the bottom surface (surface closest to or facing wall 14) of the cell culture device. Adjacent mating protrusion 50b has a retaining rib which projects downwards (e.g., in the direction of wall 14), thus engaging a cell culture device 40 along the top surface (surface closest to or facing wall 16) of the cell culture device. As illustrated in FIGs 1, 2 & 5-7, a portion of the housing comprising holder 10, and located as part of or along back wall 18, functions as a stop 42 for defining or limiting the depth of insertion as the cell culture device is slidably received into the holder 10. In a preferred embodiment, stops 42 are molded as part of back wall 18. For example, upwardly extending stops 42 each comprise a ridge which functions to prevent a cell culture device inserted into holder 10 from extending beyond back wall 18. In an embodiment wherein holder 10 is comprised of assembled parts comprising walls 12a, 12b, 14, 16, and 18, stops 42 may either be formed along the respective edges of walls 12a and 12b closest to wall 18, or may be formed by wall 18
being secured together in the unit form. In a preferred embodiment, and as illustrated in FIGs. 3-5 & 7, stops 42 limit the depth of insertion of cell culture device 40 such that, after being slid into and received and secured by holder 10, a portion of the cell culture device extends outwardly from and slightly beyond open front 20, thereby providing surfaces which can be easily grasped by a user in sliding cell culture device out of holder 10. In this preferred embodiment, the holder comprises an organizer that provides easy access to, and easy viewing of, cell culture devices stored therein. Further, the stops may provide a space between the back wall and inserted cell culture devices which enhances the air flow in the holder.
As relating to back wall 18, it may comprise one of several configurations in functioning to provide structural integrity to holder 10. In one embodiment, as illustrated in FIGs. 2 & 6-7, back wall 18 extends from side walls 12a to 12b, and from wall 16 to wall 14 in fully covering that portion of holder 10 extending therebetween. As illustrated in FIG. 6, a plurality of backwall slots 58 may facilitate flow of air through holder 10 for access by cells in the one or more cell culture devices contained within holder 10 during an incubation process. In another embodiment, back wall 18 does not fully cover the portion of holder 10 exten- ding between side walls 12a and 12b, but is sufficient to provide structural integrity to holder 10. To illustrate this latter embodiment, as illustrated in FIGs. 1 & 5, wall 18 is in an "X" or criss-cross configuration in extending from side walls 12a to 12b, and from wall 16 to wall 14, in providing structural integrity to holder 10. In a tissue culture incubator, and where holder 10 comprises wall 18 in the criss-cross configuration (as compared to a solid wall 18) , flow of air is facilitated through holder 10 for access
by cells in the one or more cell culture devices contained within holder 10.
In another embodiment of holder 10, as further shown in FIG. 4, one or both of walls 12a and 12b have one or more side wall slots 52 which extend along a majority of the wall length. As shown in FIG. 4, a side wall slot 52 is strategically placed so as to be aligned with an aperture 45 of cell culture device 40 when fully inserted in a length-wise manner into holder 10. In this arrangement, holder 10 can function to hold cell culture device in place, in a hands- free operation, while the user injects a substance into, or withdraws a substance from the cell culture device via one or more apertures 45, and through the respectively aligned side wall slot 52. Additionally, a plurality of cell cul- ture devices contained in holder 10 can be placed in fluid flow connection by running tubing from a cell culture device to an adjacent cell culture device via their respective apertures 45, and through the respectively aligned side wall slots 52. Alternatively, and as illustrated in FIGs. 7, 8, & 10, the cell culture devices are fully inserted in a width-wise manner into holder 10. In this arrangement, the one or more apertures 45 are fully accessible, at the opening of the holder, for a user to inject a substance into, or withdraw a substance from the cell culture device via the one or more apertures 45. Additionally, a plurality of cell culture devices contained in holder 10 can be in placed in fluid flow connection by running tubing from a cell culture device to an adjacent cell culture device via their respective apertures 45. In use, and as illustrated in FIGs. 3-5 & 7-10, holder 10 can be partially or completely filled with a plurality of cell culture devices 40 in forming a multi-pack. The multi- pack may then be utilized in one or more processes includ-
ing, but not limited to, storing, handling, manipulating, and culturing of the one or more cell culture devices contained within the holder. During one or more of these processes, the cell culture devices may contain cell culture medium, or may be devoid of cell culture medium. For example, one or more cell culture devices may be filled with a combination of components comprising cell culture medium and the cells desired to be cultured. Holder 10 may then be partially or completely loaded with filled cell culture devices in forming a multi-pack. The multi-pack may then be placed on the shelf of an incubator in the process of incubating the one or more cell cultures contained therein at the desired temperature and time of incubation.
In another preferred embodiment of the holder according to the present invention, the holder further comprises a plurality of interlocking connectors. The interlocking connectors allow for a plurality of holders to be interlocked together thereby increasing storage capacity by forming an assembled unit, as well as allowing a user to build an assembled unit of a desired total storage capacity depending on the number of modular holders used to form the assembled unit. Preferably, the interlocking connectors are molded as areas which protrude from the respective surface on which they are located, in maintaining a one piece construction for the holder. In a preferred embodiment, and as illustrated in FIGs. 6-8, each interlocking connector 60, extending from and along the surface to which it is or made a part of, comprises a tongue and groove combination. As illustrated in FIG. 10, interlocking connectors of one holder are used to slide into and securely engage interlocking connectors of an adjacent holder in interlocking a plurality of holders together. Thus, the tongue and groove of an interlocking connector of a holder provides an interlocking connection
with complementary elements on an adjacent holder. In interlocking two holders together by their adjacent surfaces, the tongues of interlocking connectors on the adjacent surface of a first holder are aligned to the grooves of interlocking connectors on the adjacent surface of a second holder, and then the user slides one holder in relation to the other holder so that the tongues of interlocking connectors of the first holder slide along and are engaged by the grooves of interlocking connectors of the second holder, and the tongues of interlocking connectors of the second holder slide along and are engaged by the grooves of the interlocking connectors of the first holder. Thus, in referring to FIG. 10, assembled unit 65 comprises holder 10a interlocked with holder 10b which is also interlocked with holder 10c. Holder 10a is interlocked with holder 10b by securedly engaging interlocking connectors 60a & 60b of holder 10a with interlocking connectors 60c & 60d of holder 10b, respectively. In a similar manner, holder 10b is interlocked with holder 10c by securedly engaging inter- locking connectors 60e & 60f of holder 10b with interlocking connectors 60g & 60h of holder 10c, respectively. While FIG. 10 shows an assembled unit comprising three interlocked holders for illustrative purposes only, it will be apparent to one skilled in the art from these descriptions that an assembled unit can comprise two interlocked holders, or can comprise more than three interlocked holders, depending on the user's requirement for total storage capacity (e.g., the number of cell culture devices desired to be stored in the assembled unit) .
The foregoing description of the specific embodiments of the present invention have been described in detail for purposes of illustration. In view of the
descriptions and illustrations, others skilled in the art can, by applying, current knowledge, readily modify and/or adapt the present invention for various applications without departing from the basic concept, and therefore such modifications and/or adaptations are intended to be within the meaning and scope of the appended claims.
What is claimed: