WO2018035182A1

WO2018035182A1 - Storage and preservation of living tissue allografts

Info

Publication number: WO2018035182A1
Application number: PCT/US2017/047059
Authority: WO
Inventors: Gordana Vunjak-Novakovic; Keith Yeager; David Liu
Original assignee: The Trustees Of Columbia University In The City Of New York
Priority date: 2016-08-16
Filing date: 2017-08-16
Publication date: 2018-02-22

Abstract

Provided are devices, systems and methods for storing and preserving living tissue allografts. The systems are simple, robust and yet have multiple functionalities. The purpose is to provide automated and highly controlled maintenance of viable tissues over periods of time sufficient for the evaluation, typing and matching of tissue grafts for transplantation.

Description

STORAGE AND PRESERVATION OF LIVING TISSUE ALLOGRAFTS

[0001] A system, device and method for storing and preserving living tissue allografts are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present application claims priority to U.S. Provisional Application No.

62/375,546, filed on August 16, 2016, the content of which is hereby incorporated by reference in its entirety.

BACKGROUND

[0003] Cartilage injuries alone affect approximately 900,000 Americans annually, resulting in more than 200,000 surgical procedures in which fresh osteochondral allografts are employed to treat patients. Once graft positioning, size, and thickness are given careful attention, the key to successful allograft transplantation is cell viability. Studies have shown that histological, biomechanical and chemical characteristics of fresh osteochondral grafts may be maintained in storage for up to 28 days. However, practically half of this time is spent screening the tissue for diseases and checking sterility, and tissue matching may require another 2 weeks, leaving a short window for actual implanting of the tissue into a patient.

[0004] Although there is some variation of protocols for osteochondral allograft preservation, they are typically preserved according to guidelines from the American Association of Tissue Banks (AATB) at 4°C and used within 28 days of donor harvest, of which the window of opportunity for implantation is limited to 14 days due to a 2-week disease testing protocol. However, within this window for "viable" implants, despite the presence of a clinically relevant number of "live" cells (i.e. 50% by live/dead assay) cellular health may nonetheless be greatly compromised. After 14 and 28 days of storage, only 20% and 15% of initial viability may remain.

[0005] By the time allografts are ready for implantation, however, cell viability is compromised, and the window for implantation is short. Extended storage under current protocols can result in limited cell viability and a short window for safe transplantation which accounts for up to 20% and 35% failure rate after 5 and 25 years. The increase of cell viability from 50% to 85% could also drive changes in FDA standards for clinically used allografts. Better maintenance of cell viability in osteochondral grafts would increase both clinical outcomes and the window for clinical use compared to current levels.

[0006] To address this issue, grafts may be stored at 37 C, which aids in preservation of viability, biochemical and biomechanical properties, as compared to those stored at 4 C. However, there is concern about the increased risks that this temperature poses to tissue damage due to bacterial and fungal infections. A pressing need remains, therefore, to not only extend the clinical window for "viable" grafts, but also to improve graft viability.

SUMMARY

[0007] Provided is a unit for storing and preserving living tissue. In one embodiment, the unit comprises the following: a housing containing a first cooling chamber and a second non- cooling chamber, and an insulating member disposed between the first cooling chamber and the second non-cooling chamber, wherein the insulating member includes an opening to permit fluid communication between the first and second chambers; a media carrying unit insulatingly disposed in the first cooling chamber, the media carrying unit comprising one or more stations for engaging and suspending a media container; and a tray unit for holding one or more bioreactors insulatingly disposed in the second non-cooling chamber.

[0008] The unit may also comprise a system for gas exchange and mixing (such C0₂/air) that provides an atmosphere inside the unit suitable for storing and preserving living tissue; and a system for fluid mixing by agitation, such as via magnetic stir bar, vibration (mild vortexing), or oscillatory motion (planar, or rotational).

[0009] In another embodiment, the unit comprises the following: a housing containing first cooling chamber and a second non-cooling chamber, and an insulating member disposed between the first cooling chamber and the second non-cooling chamber, wherein the insulating member includes an opening to permit fluid communication between the first and second chambers; a media carrying unit insulatingly disposed in the first cooling chamber, the media carrying unit comprising one or more containers containing perfusion media; and a tray unit containing one or more bioreactors and insulatingly disposed in the second non-cooling chamber and separate from the first cooling chamber, and one or more fluid conduits in communication with both the one or more containers containing perfusion media and the one or more bioreactors, and one or more control valves operatively engaged to one or more fluid conduits. [0010] In one aspect is a device for storing and preserving living tissue, comprising a first cooling chamber including a container adapted to contain and dispense a fluid perfusion medium, and a second non-cooling chamber including a perfusion bioreactor comprising an enclosed storage environment adapted to store living tissue immersed in the fluid perfusion medium. The first cooling chamber is in fluid communication with the second chamber, for example through a first fluid conduit. In some embodiments, the second non-cooling chamber is in fluid communication with a waste receiver through a second fluid conduit. In operation, fluid perfusion medium is supplied from the first cooling chamber to the enclosed storage environment through the first fluid conduit and may be drained from the enclosed storage environment to the waste receiver through the second fluid conduit.

[0011] In another aspect, a system is provided for storing and preserving a plurality of living tissues. In this regard, the first cooling chamber contains a media carrying unit including a plurality of stations designed to engage or otherwise hold a plurality of containers, such as media bags. The second non-cooling chamber contains a tray adapted to hold a plurality of bioreactors such as by a second plurality of stations. In one embodiment, the media carrying unit and the tray unit are one integrated unit having a carousel design. The first cooling chamber and the second non cooling chamber are in fluid communication. For example, each media station is in fluid communication with each bioreactor station.

[0012] In another aspect, is provided a kit comprising a fluid impermeable outer container comprising a port in the lower portion adapted to be in fluid communication with a fluid conduit; a shelf, lip or protrusion on the interior to support an inner container (ii), and an opening in the upper portion adapted to receive and sealably engage a lid (iii); a fluid permeable container adapted to fit within the outer container and allow a fluid perfusion medium to pass therethrough; and a lid comprising a port adapted to be in fluid communication with a fluid conduit, adapted to sealably engage the outer container and close the opening in the outer container; an optional opening for gas exchange; and optionally adapted to provide a gripping mechanism.

[0013] Some embodiments of the kit include those wherein the kit of further comprises a magnetic stir bar; a first fluid conduit and a fitment adapted to operatively engage the port in the outer container (i) and a second fluid conduit and a fitment adapted to operatively engage the port in the lid (iii); and/or a container containing a fluid perfusion medium adapted to sustain and preserve living tissue when contained in the outer container (i) and adapted to operatively engage the second fluid conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIGURE 1 is a schematic view of a device for storage and preservation of a living tissue allograft.

[0015] FIGURE 2A shows perspective (left) and cross-sectional view (right) of a perfusion bioreactor unit used in the system described herein.

[0016] FIGURE 2B shows an additional cross-sectional view of a perfusion bioreactor unit used in the system described herein.

[0017] FIGURE 3 depicts aspects of the present system designed for storage and preservation unit of a plurality of living tissues.

[0018] FIGURE 4 depicts a system configuration comprising a common media storage container for delivering media to multiple perfusion bioreactor units (left) and a magnified view depicting the configuration of the perfusion bioreacture units (right) in a system designed for storage and preservation unit of a plurality of living tissues.

[0019] FIGURE 5 depicts a configuration comprising multiple media storage containers each delivering tissue-specific media to a separate perfusion bioreactor unit (left) and a magnified view depicting the configuration of the perfusion bioreacture units (right) in a system designed for storage and preservation unit of a plurality of living tissues.

[0020] FIGURE 6 depicts an alternative configuration of a system designed for storage and preservation unit of a plurality of living tissues where an additional cooling chamber is provided for storing and delivering frozen supplement aliquots.

[0021] FIGURE 7 depicts an alternative configuration of a system designed for storage and preservation unit of a plurality of living tissues comprising a cooling chamber for storing and delivering pre-mixed media aliquots and a non-cooling chamber for providing a suitable environment for engineering tissues.

DETAILED DESCRIPTION

[0022] The systems, devices and methods described herein enable preservation of high viability of osteochondral tissue allografts during storage (at least one month) and transport using an environmentally controlled bioreactor system. Advanced in vitro bioreactor systems have been developed to characterize, describe and recapitulate native in vivo environments. We have now developed a system to use perfusion bioreactors, which we have previously used for the successful engineering of bone and cartilage, with additional process control, to maintain high viability of osteochondral tissue allografts, including bone and/or cartilage tissues.

[0023] Specifically, the system would maintain cell viability of >85% over one month, which is the time needed for tissue evaluation and matching, and during transport to the site where tissue will be implanted into the patient. To our knowledge, this would be the first bioreactor-based method specifically addressing the unmet need of increased cellular viability where it can be affected most directly - not by slowing the metabolism of the cells, but by providing nutrients and the environment needed for the cells within a living tissue to survive and thrive.

[0024] The system preserves osteochondral allografts in an environment that maintains cell viability (oxygen levels at 2-10%, temperature from 4-37C), utilizing a bioreactor system for constant supply of fresh conditioned nutrients. As a result, cell viability will increase from less than 50% to at least 85%, which is a critical difference for the biological quality of the graft. We anticipate that clinical success of graft implantation will radically improve as a result of increase in cell viability.

[0025] Viability of stored allograft tissues will improve and the shelf life will be extended compared to conventionally stored tissues. Tissue Banks and clinicians will have sufficient time for testing the tissue grafts and matching them to the patients, leading to improved matches, reduced tissue waste, improved clinical outcomes upon transplantation, with reduced failure rate and fewer revision surgeries.

[0026] Other possible applications for the system described herein include the potential to expand to preservation of other tissue types.

[0027] Described herein is a tissue storage and preservation system and unit. These tissue storage and preservation systems may be understood by reference to the Figures herein.

[0028] As shown schematically in FIG. 1, a system for storing and preserving living tissue 1 comprises: a first cooling chamber 100 including a container 110 (represented by a media preservation bag as a preferred embodiment) adapted to contain and dispense a fluid perfusion medium, in fluid communication with (b) through a first fluid conduit 120; and

a second non-cooling chamber 200 including a perfusion bioreactor 210 comprising an enclosed storage environment adapted to store living tissue 280 immersed in the fluid perfusion medium, in fluid communication with a waste receiver 300 through a second fluid conduit 220;

wherein the fluid perfusion medium is supplied from (a) to the enclosed storage environment through the first fluid conduit and drained from the enclosed storage environment to (c) through the second fluid conduit.

[0029] The storage and preservation systems described herein may include one or more the following features set forth below.

[0030] The system may further comprise a first control valve 150 is operatively engaged to the first fluid conduit 120 and a second control valve 250 is operatively engaged to the second fluid conduit 220.

[0031] The system may further comprise an insulating member between the cooling chamber and the second non-cooling chamber with a passage through the insulating member to allow fluid communication between (a) and (b).

[0032] In certain aspects, the perfusion medium container 110 is positioned above the bioreactor 210 and the bioreactor 210 is positioned above the waste receiver 300. This allows the perfusion medium to flow easily by gravity from the perfusion medium container 110 to the bioreactor 210 and from the bioreactor 210 to the waste receiver 300.

[0033] The system may comprise a plurality of perfusion medium containers 110 and an equal plurality of bioreactors 210; wherein each unit of 110 is in fluid communication with one unit of 210 to provide a plurality of 110-210 combinations; wherein each unit of 110 is positioned above each unit of 210 and each 110-210 combination is positioned above the waste receiver 300.

[0034] Alternatively, the system may comprise a single perfusion medium container in fluid communication with each bioreactor unit 210 in the instance the tissues don't require separate types of media. [0035] In certain embodiments, the plurality of 1 10-210 combinations are arranged in a single row.

[0036] In certain other embodiments, the plurality of 110-210 combinations are arranged around a rotatable vertical center axis.

[0037] In certain embodiments, the temperature of the second non-cooling chamber may range from room temperature to typical incubator temperature (such 37 C). The system also maintains appropriate C0₂ levels (about 5%). The appropriate gas levels can be supplied by exchanging premixed gas, or the system may include components to mix levels, essentially making this second chamber a typical incubator. In another aspect, a nitrogen gas source is in communication with the second chamber to create a hypoxic environment in the second chamber.

[0038] As can be seen in FIGURES 2A and 2B, one embodiment of the perfusion bioreactor (210) is shown in perspective and cutaway drawings. The bioreactor of this embodiment comprises the following: an enclosed storage container comprising a fluid impermeable outer container 211 comprising a port 222 in the lower portion in fluid communication with the second fluid conduit 220 (not shown); a shelf, lip or protrusion 219 on the interior to support an inner container 212, and an opening in the upper portion adapted to receive and sealably engage a lid 213; an inner fluid permeable container 212 within the outer container 211 adapted to support the living tissue and allow the fluid perfusion medium to pass therethrough and contact and immerse the living tissue; a lid 213 comprising a port 214 in fluid communication with the first fluid conduit, adapted to sealably engage the outer container and close the opening in the outer container; an optional opening for gas exchange 215; and optionally adapted to provide a gripping mechanism 216; and a magnetic stirrer 235 to stir the fluid perfusion medium.

[0039] In this embodiment, the fluid impermeable outer container 211 has a generally cylindrical body with a closed end and an open end. In the upper portion adjacent to the open end is a lid engagement area 218 on the inner surface of the outer container 211. The lid engagement area comprises a surface adapted to engage a complementary surface on the lid to provide an enclosed storage environment within the perfusion bioreactor 210. The lid engagement area may comprise a generally smooth surface that friction-fits to the lid. Alternatively, the lid engagement area 218 may comprise shaped elements that engage complementary shaped elements on the lid, such as screw threads, interrupted screws or other twist-lock components (not shown).

[0040] Alternatively, the lid engagement area 218 may be adjacent to the open end on the outer surface of the outer container 211 to engage a portion of the lid that overlaps the outside of the outer container 211. The lid engagement area 218 in this alternative embodiment may also comprise elements that engage complementary elements on the lid, including for example, a lip that can engage the lid to provide a snap-fit closure, screw threads, interrupted screws or other twist-lock components.

[0041] In the illustrated embodiment, a circumferential shelf 219 in the upper portion near the open end on the inner surface engages the rim 221 of the inner container 212 to support the inner container inside the outer container 211. Alternatively, 219 may be a lip or protrusion on the inner surface of the outer container. The lip or protrusion may be continuous around the circumference of the open end, or it may be interrupted to engage one or more protrusions on the rim 221 to limit rotation of the inner container 212 within the outer container 211. Alternatively, the shelf, lip or protrusion may be in the lower portion of the outer container and supports the bottom of the inner container 212.

[0042] A port 222 is located in the lower portion of the outer container adapted to be in fluid communication with the second fluid conduit 220 (not shown). As shown in Fig. 2B, the port 222 may further comprise a fitment to engage the second fluid conduit. The fitment may be a hose barb, or it may comprise two complementary connecting parts such as the luer port shown. One part of the fitment 226b engages the port 222 and the other part 226a engages the fluid conduit 220. Alternatively, the fitment may comprise a resealable septum.

[0043] The fluid capacity of the outer container may be from 30 ml to 300 ml, preferably

100 ml. The outer container desirably comprises a rigid or semi-rigid highly transparent material to enable visual inspection of the contents of the container when the bioreactor is in operation.

[0044] An inner fluid permeable container 212 within the outer container 211 is adapted to support the living tissue and allow the fluid perfusion medium to pass therethrough and contact and immerse the living tissue. In the embodiment shown in FIGURES 2A and 2B, the inner container 212 may comprises a body in a truncated conical shape with a rim 221 that is supported by shelf 219 of the outer container 211. The height of the inner container 212 is shorter than that of the outer container 211, so that sufficient space is available in the lower portion of the outer container to accommodate a magnetic stir bar 235 that can rotate freely without contacting the inner container 212. The body of the fluid permeable container is perforated or fenestrated (not shown) to allow the perfusion medium to flow freely through the inner container 212. The body of the inner container 212 may comprise a rigid or semi-rigid material. Alternatively, the body of the inner container 212 may comprise a perforated flexible film conformed in a pouch or sack to contain and support the living tissue.

[0045] The lid 213 is adapted to sealably engage and close the opening in the outer container 211. In the embodiment illustrated in FIGURES 2A and 2B, the lid 213 is generally disk-shaped with a flange that projects from the top portion of the edge of the lid 213 to overlay the top edge of the open end of the outer container 211. An o-ring or gasket 217 comprising elastic compressible material is accommodated in a groove of the flange. The gasket 217 may be held in place by physical means such as a groove as shown, or adhered to the lid 213. The gasket may comprise a thick coating of elastic compressible material on a circumferential portion of the surface of the lid 213. Alternatively, the gasket may be positioned at or near the top edge of the outer container 211, or at or near the rim 221 of the inner container 212, to contact the inner or lower surface of the lid.

[0046] The lower portion of the edge of the lid is adapted to engage the lid engagement area 218 of the outer container 211. As described above, the lid 213 may comprise shaped elements that engage complementary shaped elements on the lid engagement area 218 of the outer container 211, such as screw threads, interrupted screws or other twist-lock components (not shown). When the lid 213 is properly engaged with the lid engagement area 218, the gasket 217 is compressed and forms a tight seal between the outer container 211 and the lid 213, providing a sealed environment.

[0047] Alternatively, as described above, the lid engagement area 218 may be adjacent to the open end on the outer surface of the outer container 211 and a portion of the lid overlaps the outside of the outer container 211. The lid in this alternative embodiment may also comprise elements that engage complementary elements on the outer container, including for example, a flap that can engage the outer container to provide a snap-fit closure, screw threads, interrupted screws or other twist-lock components.

[0048] The lid 213 also comprises a port 214 in fluid communication with the first fluid conduit 120 (not shown). As shown in FIGURE 2B, the port 214 may further comprise a fitment to engage the first fluid conduit 120. The fitment may be a hose barb, or it may comprise two complementary connecting parts such as the luer port shown. One part of the fitment 225b engages the port 214 and the other part 225a engages the first fluid conduit 120. Alternatively, the fitment may comprise a resealable septum.

[0049] In an alternative embodiment, the port in fluid communication with the first fluid conduit 120 may be positioned in the upper portion of the outer container 211 and not in the lid 213.

[0050] The lid 213 may optionally comprise one or more openings for gas exchange 215 with a gas supplied from outside the container. The gas exchange opening(s) 215 may be optionally covered by a polydimethylsiloxane (PDMS) sheet. Alternatively, the gas exchange opening(s) 215 may comprise a fitment (not shown) such as a hose barb, luer port or resealable septum adapted to provide gas communication with a fluid conduit to a gas supply; a filter may also be attached to this port to maintain sterility.

[0051] The lid 213 may be optionally adapted to provide a gripping mechanism 216 to make manipulation of the lid easier. As depicted in FIGURES 2A and 2B, the gripping mechanism 216 may comprise indentations in the upper surface of the lid to accommodate fingers and/or thumb of the user. Alternatively, the outer edge of the lid may be textured such as by knurling, milling or the like to provide a gripping surface.

[0052] It is desirable that the materials for all the components of the bioreactor can be sterilized, such as by irradiation, autoclaving, or ethylene oxide treatment, to prevent undesirable bacteria, mold or yeast spores, or other contaminants that could interfere with the preservation of the living tissue allografts. It is also desirable that the components be disposable after a single use to minimize contamination of the living tissue in subsequent storage operations.

[0053] FIGURE 3 shows a cross section of an interior of an embodiment of a storage unit described herein. As shown in FIGURE 3, the storage unit 10 comprises a housing 11, an insulating member 14 divides the interior of the housing 11 into a first cooling chamber 12 and a second non-cooling chamber 13 and the insulating member includes an opening 15 to permit fluid communication between the first and second chambers. A cooling unit 16 is mounted within the first cooling chamber. An air tube 17 in fluid communication with a supply of gas (not shown) is mounted within the second non-cooling chamber 13. A door or wall (not shown) can be employed so that the interior chambers are insulatingly isolated from each other and the external environment.

[0054] The insulating member 14 may comprise sub-members that are configured to be removable to enable access to parts of the storage unit, such as the media carrying unit, the tray unit and the center unit and fit together inside the storage unit to provide a complete insulating member. The insulating member 14 may comprise an air gap, insulating foam, insulating fiber bat(s), combinations thereof, or the like to provide a thermal break between cooling chamber 12 and the non-cooling chamber 13 so that they can be independently operated at different temperatures. In operation, a predetermined temperature is maintained within the environment defined by the first cooling chamber 12, such as wherein the predetermined temperature is between about 0 to about 4 C, and the second non-cooling chamber 13 defines an environment having a temperature controlled between about 10 to about 38 C. For example, the first cooling chamber 12 defines an environment having a controlled temperature of about 0 to about 4 C and the second non-cooling chamber 13 defines an environment at about room temperature.

[0055] The air tube 17 is adapted to deliver a fresh supply of gas, such as air or a mixture of gases at a predefined concentration, (e.g. a gas mixture comprising 5 % of C0₂) during operation of the unit to store and preserve the tissue. Valves can be used to regulate the flow of gas through the chamber. Valves may be controllable manually or via a microprocessor, and can be solenoid (electronic), hydraulic (liquid), or pneumatic (air) in actuation. Additionally, a nitrogen gas source can be placed in communication with air tube or directly to the second chamber to allow purging of the environment with nitrogen gas to create a hypoxic environment.

[0056] A media carrying unit 21 is insulatingly disposed in the first cooling chamber 12, the media carrying unit comprising a plurality of stations 22 for engaging and suspending a media bag (not shown). A tray unit 23 adapted to hold a plurality of bioreactors (not shown) is insulatingly disposed in the second non-cooling chamber 13. In this embodiment, the media carrying unit 21 and the tray unit 23 are both operatively connected to a common center unit 20 passing through the insulating member 14, and the center unit or axle 20 is rotatable about a vertical central axis 24 such as in a carousel design.

[0057] In the embodiment depicted, the center unit 20 comprises a plurality of first control valves 25 adapted to operatively engage a plurality of first fluid conduits (not shown) passing through the opening 15 in the insulating member 14; and a plurality of optional second control valves 26 adapted to operatively engage a plurality of second fluid conduits (not shown). The center unit 20 further comprises a plurality of magnetic devices 27 adapted to operatively engage a plurality of magnetic stir bars (not shown).

[0058] In one embodiment (shown in FIGURE 3), the control valves 25 and 26 may be manually-operated pinch valves that compress a flexible tubing fluid conduit when closed. Fluid flow occurs because of gravity — the media bag is located higher than the bioreactor. Alternately, a peristaltic pump may be implemented to drive media flow. When opened, the valves allow fluid to flow through the conduit. Alternatively, the control valves may be controllable so that the flow of fluid through the conduit can be adjusted to a defined flow rate or stopped. In other embodiments, the valves may be power-operated and controlled (such as with electric solenoid valves) to regulate flow of the perfusion fluid through the fluid conduits.

[0059] FIGURE 4 shows photographs of the interior of the storage unit 10 with the center unit 20 loaded with a plurality of bioreactors 210 according to the embodiment depicted in FIGURES 2A and 2B and a perfusion fluid container 1 10 (e.g. a media bag). The insulating member 14 has been removed for better visualization. The photograph on the right shows an enlarged image of the tray unit and the lower part of the center unit.

[0060] The upper portion of the center unit accommodates the media carrying unit 21, in which a media bag 110 is shown suspended from station 22. In the embodiment shown, the media carrying unit is configured so that there is one media bag per bioreactor. Alternately, the media carrying unit may comprise one common media source for all bioreactors, with capability for engaging multiple fluid conduits to supply perfusion medium to all the bioreactors. Below the media carrying unit 21, the center unit comprises an insulated disk 28, having a diameter slightly smaller than the opening 15 in the insulation member 14 and cutouts at the edge for fluid conduits 120 to pass through. This allows the center unit to rotate freely when the insulating member 14 is installed and still provide a thermal break between cooling chamber 12 and non- cooling chamber 13. Fluid conduit 120 passes through a first control valve 250 and engages fitment 225 positioned on the lid 213 of the bioreactor 210, loaded onto the tray unit 23. The fenestrated inner container 212 is visible inside the transparent outer container 211 of the bioreactor 210. A (simulated) portion of living tissue 280 supported by the inner container 212 is also visible. A magnetic stir bar 235 is positioned at the bottom of the bioreactor 210 and is operatively engaged with a magnetic device 27, such as an electromagnetic coil or a motor-spun magnet that produces a magnetic field capable of rotating the magnetic stir bar 235. A fitment 226 in the lower portion of the outer container 211 engages fluid conduit 220, which leads to waste receiver 300 at the bottom of the storage unit.

[0061] FIGURE 5 shows photographs of the interior of the storage unit 10 with the center unit 20 loaded with a plurality of bioreactors 210 according to the embodiment depicted in FIGURES 2A and 2B and a plurality of perfusion fluid containers 110 (e.g. media bags). The insulating member 14 has been installed. The photograph on the right shows an enlarged image of the tray unit and the lower part of the center unit. The upper portion of the center unit accommodates the media carrying unit 21, in which a plurality of media bags 110 are suspended from stations 22. Fluid conduit 120 passes through a first control valve 250 and engages fitment 225 positioned on the lid 213 of the bioreactor 210, loaded onto the tray unit 23. The fenestrated inner container 212 is visible inside the transparent outer container 211 of the bioreactor 210. A (simulated) portion of living tissue 280 supported by the inner container 212 is also visible. A magnetic stir bar 235 is positioned at the bottom of the bioreactor 210 and is operatively engaged with a magnetic device 27, such as an electromagnetic coil or a motor-spun magnet that produces a magnetic field capable of rotating the magnetic stir bar 235. A fitment 226 in the lower portion of the outer container 211 engages fluid conduit 220, which is in operative communication with second control valve 250 leads to waste receiver 300 at the bottom of the storage unit. Fluid perfusion medium (simulated by colored water) 170 is contained in each of the media bags 110. A portion of perfusion medium 270 has been dispensed from the media bags 110 into the bioreactors 210. The system is shown ready for storage and preservation of the living tissue according to the following description.

[0062] Referring now to FIGURE 6, an alternative configuration 400 is provided for delivering media supplements. In this embodiment, a third chamber 410 is positioned above media coooling chamber 420 (which is kept at, for example, 4°C) and is adapted to store a plurality of supplement aliquots 412 at, for example, -20°C. A third valve 414 permits delivery of a supplement aliquot 412 to a mixing reservoir 430 in the media cooling chamber 420 via passage 416. A bulk media storage container 440 is in fluid communication with the mixing reservoir 430 where the media is mixed with the supplement aliquot 412. Mixing reservoir 430 may further comprise a magnetic stir bar, vibration (mild vortexing), or oscillatory motion (planar, or rotational) to facilitate mixing of the supplement aliquot 412 with the bulk media delivered from the bulk media storage container 440. The supplemented media would then be delivered to each perfusion bioreactor unit 450 in a non-cooling chamber 460 from the mixing reservoir 430 via a first series of fluid conduits 432 each fitted with a valve 434 to control delivery to the perfusion bioreactor units 450. The non-cooling chamber 460 provides an enclosed storage environment adapted to store living tissue immersed in the fluid perfusion medium in each of the perfusion bioreactor units 450 (e.g., 37°C at 5% C02). Each of the perfusion bioreactor units 450 are further in fluid communication with a waste receiver 470 through a series of second fluid conduits 472 each fitted with a valve 474 to control passage through the series of second fluid conduits 472. The supplement aliquots may contain various supplements such as ascorbic acid, DMEM, TGF-beta, HEPS, or FBS. It should be understood that this alternative embodiment may comprise the various features and components as described above in the various other embodiments described herein.

[0063] Referring now to FIGURE 7, a simplified system configuration 500 is described.

Here, only two chambers are required: a cooling storage chamber 510 to store a plurality of frozen, pre-mixed media aliquots 512; and a non-cooling chamber 520 comprising a distribution reservoir 530, one or more perfusion bioreactor units 540 and a waste receiver 550. In this embodiment, the cooling storage chamber 410 is positioned above the non-cooling chamber 520 and is adapted to store the plurality of frozen, pre-mixed media aliquots 512 at, for example, - 20°C. A valve 514 permits delivery of a frozen media aliquot 512 to the distribution reservoir 530 in the non-cooling chamber 520 via passage 516. The frozen media aliquot 512 is mixed and melted in the distribution reservoir 530 and then delivered to the one or more perfusion bioreactor units 540 via a first series of fluid conduits 532 each fitted with a valve 534 to control delivery to the perfusion bioreactor units 550. The non-cooling chamber 520 provides an enclosed storage environment adapted to store living tissue immersed in the fluid perfusion medium in each of the perfusion bioreactor units 540 (e.g., 37°C at 5% C02). Each of the perfusion bioreactor units 540 are further in fluid communication with a waste receiver 550 through a series of second fluid conduits 552 each fitted with a valve 554 to control passage through the series of second fluid conduits 552. The media aliquots 512 may comprise only media or a combination of media and supplements as desired. The simplified configuration eliminates the need for a third chamber to contain refrigerated media. It should be understood that this alternative embodiment may comprise the various features and components as described above in the various other embodiments described herein.

[0064] A sample of living tissue is obtained. The living tissue may comprise a bioscaffold. The living tissue preferably comprises osteochondral tissue. The living tissue is placed inside a bioreactor as described herein. Preferably the living tissue is placed into the bioreactor under generally aseptic conditions, to prevent inclusion of undesirable organisms or infectious agents that could interfere with successfully storing and preserving (maintenance of cell structural and functional integrity and viability of at least 85% for a period of at least 28 days) the living tissue.

[0065] A container (such as a media bag) containing perfusion medium is provided and placed in the first cooling chamber of the storage unit described herein, such as in the media carrying unit described herein. The media bag is configured to contain perfusion fluid sufficient to sustain living tissue in the bioreactor for a desired storage period of time, such as over 28 days. For example, the media bag may contain up to about 0.5 liters of perfusion fluid. The media bag is also configured to be in fluid communication with a fluid conduit, such as by a fitment; and dispense the perfusion fluid into the fluid conduit. The perfusion medium comprises nutrients capable of sustaining the living tissue (e.g. Dulbecco's Modified Eagle Medium) during the storage period while maintaining cell structural and functional integrity and viability of at least 85% for a period of at least 28 days. The perfusion medium may also comprise other agents including for example preservatives, stabilizers, antimicrobial agents (sodium pyruvate, HEPES buffer, penicillin/streptomycin, ITS supplement, proline, dexamethasone, ascorbic acid, etc) that contribute to sustaining and preserving the living tissue. Preferably the perfusion medium and the media bag were prepared under aseptic conditions. As noted above, the perfusion medium may alternatively be contained in a common medium container supplying perfusion medium to multiple bioreactors.

[0066] The bioreactor containing living tissue is placed in the second non-cooling chamber of the storage unit described herein.

[0067] Preferably, the storage unit is operated so that a predetermined temperature is maintained within the environment defined by the first cooling chamber, such as wherein the predetermined temperature is from about 0 to about 4 C. Preferably, the storage unit is operated so that the second non-cooling chamber defines an environment having a temperature controlled between about 10 and about 38 C. More preferably, the storage unit is operated so that the first cooling chamber defines an environment having a controlled temperature of about 0 to about 4 C and the second non-cooling chamber defines an environment at about room temperature.

[0068] A first fluid conduit is connected to the perfusion medium container and the bioreactor to provide fluid communication between them. The fluid conduit is operatively engaged with a first control valve; the valve is opened to dispense a portion of the perfusion medium from the perfusion medium container through the fluid conduit into the bioreactor sufficient to immerse the living tissue contained in the bioreactor. A second fluid conduit is connected to the bioreactor to provide fluid communication between it and a waste receiver. The second fluid conduit is operatively engaged with a second control valve configured to remove perfusion medium from the bioreactor.

[0069] Each bioreactor contains a magnetic stirrer such as a stir bar operatively engaged to a magnetic device to stir the perfusion medium in each bioreactor, providing fluid mixing. Stirring may be continuous throughout the storage period. Alternatively, stirring may be discontinuous, wherein the stirring is conducted for a short period of time at periodic intervals, such as stirring the perfusion medium for 1 to 5 minutes at one-hour intervals. Other means for fluid mixing by agitation are envisioned, such as via vibration (mild vortexing), or oscillatory motion (planar, or rotational).

[0070] During the storage period, perfusion medium is dispensed from the medium container into the bioreactor via the first fluid conduit and waste (perfusion medium with depleted nutrients and waste and/or metabolites from the living tissue) removed from the bioreactor via the second fluid conduit to the waste receiver so that the perfusion medium in the bioreactor is refreshed. The dispensing of the perfusion medium from the medium container and removal of the perfusion medium from the bioreactor may be continuous throughout the storage period, controlled by the first and second control valves (such as 5 to 50 ml per day, preferably 10 ml per day), so that a consistent volume of perfusion medium is maintained in the bioreactor. Alternatively, dispensing/removing of the perfusion medium and waste is performed at periodic intervals, such as removing 5 to 30 % of the perfusion medium in the bioreactor and replacing it with an equal volume from the medium container once per day during the storage period. Alternatively, at least one condition (e.g. low nutrient level, high metabolite level, pH, dislodged biological material) of the fluid perfusion medium in the perfusion bioreactor may be measured and at least a portion of the fluid perfusion medium in the perfusion bioreactor is replaced when the condition meets a determined threshold value. Monitoring of the perfusion medium may be accomplished by analyzing a small sample of fluid removed from the bioreactor via the second fluid conduit or via a separate sampling port. Alternatively, sensor(s) may be contacted with fluid in the bioreactor and the condition measured. Desirably, the amount of perfusion medium in the bioreactor is maintained so that the living tissue is continuously immersed in the perfusion medium throughout the storage period.

[0071] While methods, systems and devices are described herein by way of examples and embodiments, those skilled in the art recognize that the methods, systems and devices for storage and preservation of living tissue allografts are not limited to the embodiments or drawings described. It should be understood that the drawings and description are not intended to be limited to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims. Any headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used herein, the word "may" is used in a permissive sense (i.e., meaning having the potential to) rather than the mandatory sense (i.e., meaning must). Similarly, the words "include," "including," and "includes" mean including, but not limited to.

[0072] The basic components of embodiment of systems and devices for storage and preservation of living tissue are described herein. As used in the description, the terms "top," "bottom," "above," "below," "over," "under," "above," "beneath," "on top," "underneath," "up," "down," "upper," "lower," "front," "rear," "back," "forward" and "backward" refer to the objects referenced when in the orientation illustrated in the drawings, which orientation may not be necessary for using the devices or achieving the methods described herein.

[0073] Having described and illustrated the principles of the subject matter embodied herein with reference to the described embodiments, it will be recognized that the described embodiments can be modified in arrangement and detail without departing from such principles.

It should be understood that the systems, processes, or methods described herein are not related or limited to any particular type of environment, unless indicated otherwise.

[0074] In view of the many possible embodiments to which the principles of the subject matter embodied herein can be applied, we claim the subject matter embodied herein and all such embodiments as can come within the scope and spirit of the following claims and equivalents thereto.

Claims

1. A unit for storing and preserving living tissue, the unit comprising:

a housing containing a first cooling chamber and a second non-cooling chamber, and an insulating member disposed between the first cooling chamber and the second non-cooling chamber, wherein the insulating member includes an opening to permit fluid communication between the first and second chambers;

a media carrying unit insulatingly disposed in the first cooling chamber, the media carrying unit comprising one or more stations for engaging and suspending a media container; a tray unit for holding one or more bioreactors insulatingly disposed in the second non- cooling chamber;

a system for gas exchange and mixing; and

a system for fluid mixing by agitation.

2. The unit of claim 1, wherein a cooling unit is mounted within the first cooling chamber.

3. The unit of claim 1, wherein an air tube in fluid communication with a supply of gas is mounted within the second non-cooling chamber.

4. The unit of claim 1, wherein a predetermined temperature is maintained within the environment defined by the first cooling chamber.

5. The unit of claim 4, wherein the predetermined temperature is between about 0 to about 4 C.

6. The unit of claim 1, wherein the second non-cooling chamber defines an environment having a temperature controlled between about 10 to about 38 C.

7. The unit of claim 1, wherein the first cooling chamber defines an environment having a controlled temperature of about 0 to about 4 C and the second non-cooling chamber defines an environment at about room temperature.

8. A unit for storing and preserving living tissue, the unit comprising:

a housing containing first cooling chamber and a second non-cooling chamber, and an insulating member disposed between the first cooling chamber and the second non-cooling chamber, wherein the insulating member includes an opening to permit fluid communication between the first and second chambers, a media carrying unit insulatingly disposed in the first cooling chamber, the media carrying unit comprising one or more containers containing perfusion media, and

a tray unit containing one or more bioreactors and insulatingly disposed in the second non-cooling chamber and separate from the first cooling chamber, and one or more fluid conduits in communication with both the one or more containers containing perfusion media and the one or more bioreactors, and one or more control valves operatively engaged to one or more fluid conduits.

9. The unit of claim 8, wherein the bioreactor includes living tissue.

10. The unit of claim 9, wherein the living tissue is a bioscaffold.

11. The unit of claim 9, wherein the living tissue comprises osteochondral tissue.

12. The unit of claim 9, wherein the bioreactor contains a magnetic stirrer.

13. The unit of claim 8, wherein a cooling unit is mounted within the first cooling chamber.

14. The unit of claim 13, wherein a predetermined temperature is maintained within the environment defined by the first cooling chamber.

15. The unit of claim 14, wherein the predetermined temperature is from about 0 to about 4 C.

16. The unit of claim 8, wherein the second non-cooling chamber defines an environment having a temperature controlled between about 10 and about 38 C.

17. The unit of claim 8, wherein the second non-cooling chamber comprises an air tube in fluid communication with a supply of gas.

18. The unit of claim 8, wherein the first cooling chamber defines an environment having a controlled temperature of about 0 to 4 C and the second non-cooling chamber defines an environment at about room temperature.

19. The unit of claim 1, wherein the media carrying unit comprises a plurality of stations for engaging and suspending a media container; the tray unit is adapted to hold a plurality of bioreactors; and the media carrying unit and the tray unit are both operatively connected to a common center unit passing through the insulating member, wherein the center unit is rotatable about a vertical central axis.

20. The unit of claim 19, wherein the center unit comprises a plurality of first control valves adapted to operatively engage a plurality of first fluid conduits passing through the opening in the insulating member; and optionally a plurality of second control valves adapted to operatively engage a plurality of second fluid conduits.

21. The unit of claim 20, wherein the center unit further comprises a plurality of magnetic devices adapted to operatively engage a plurality of magnetic stirrers.

22. The unit of claim 20, wherein the media carrying unit comprises a plurality of media containers suspended from the plurality of stations; the tray unit comprises a plurality of bioreactors; and the plurality of first control valves are operatively engaged to a plurality of first fluid conduits in communication with both the plurality of media containers and the plurality of bioreactors.

23. The unit of claim 22, wherein the plurality of second control valves is present and the second control valves are operatively engaged to a plurality of second fluid conduits in communication with both the plurality of bioreactors and a waste receiver.

24. The unit of claim 22, wherein the plurality of media containers each contain perfusion medium.

25. The unit of claim 22, wherein the plurality of bioreactors each contain living tissue.

26. The unit of claim 25, wherein the living tissue is a bioscaffold.

27. The unit of claim 25, wherein the living tissue comprises osteochondral tissue.

28. The unit of claim 25, wherein the living tissue is immersed in perfusion medium.

29. The unit of claim 22, wherein the plurality of bioreactors contains a plurality of magnetic stirrers operatively engaged to a plurality of magnetic devices.

30. The unit of claim 22, wherein a predetermined temperature is maintained within the environment defined by the first cooling chamber.

31. The unit of claim 30, wherein the predetermined temperature is from about 0 to about 4 C.

32. The unit of claim 22, wherein the second non-cooling chamber defines an environment having a temperature controlled between about 10 and about 38 C.

33. The unit of claim 22, wherein the first cooling chamber defines an environment having a controlled temperature of about 0 to about 4 C and the second non-cooling chamber defines an environment at about room temperature.

34. The unit of claim 8, wherein the unit is adapted to maintain cell structural and functional integrity and viability of at least 85% for a period of at least 28 days.

35. A system for storing and preserving living tissue, comprising:

a first cooling chamber including a plurality of stations, each station configured to hold a container adapted to contain and dispense a fluid perfusion medium,

a second non-cooling chamber including a tray including stations adapted to hold a perfusion bioreactors, the chamber comprising an enclosed storage environment adapted to store living tissue, and

first and second fluid conduits, wherein the first fluid conduit creates a fluid communication between a first container of the first cooling chamber and a second bioreactor of the second non cooling chamber, and the second fluid conduit creates a fluid communication between a second container of the first cooling chamber and a second bioreactor of the second non cooling chamber.

36. The system of claim 35 wherein a first control valve is operatively engaged to the first fluid conduit and a second control valve is operatively engaged to the second fluid conduit.

37. The system of claim 35 further comprising an insulating member between the cooling chamber and the second non-cooling chamber with a passage through the insulating member to allow fluid communication between the first and second chambers.

38. The system of claim 35 wherein the first cooling chamber is disposed in the unit above the second non cooling chamber.

39. The system of claim 35 further including a waste reservoir.

40. The system of claim 35 wherein the first cooling chamber and the second non-cooling chamber are arranged in a single row.

41. The system of claim 35 wherein the plurality of stations of the first cooling chamber and the tray stations of the second non cooling chamber are arranged are around a rotatable vertical center axis.

42. The system of claim 35 wherein the enclosed storage container comprises

(i) a fluid impermeable outer container comprising a port in the lower portion in fluid communication with the second fluid conduit; a shelf, lip or protrusion on the interior to support an inner container (ii), and an opening in the upper portion adapted to receive and sealably engage a lid (iii);

(ii) a fluid permeable container within the outer container adapted to support the living tissue and allow the fluid perfusion medium to pass therethrough and contact and immerse the living tissue;

(iii) a lid comprising a port in fluid communication with the first fluid conduit, adapted to sealably engage the outer container and close the opening in the outer container; an optional opening for gas exchange; and optionally adapted to provide a gripping mechanism; and

(iv) a magnetic stirrer to stir the fluid perfusion medium.

43. The system of claim 35, wherein the living tissue is osteochondral tissue.

44. The system of claim 35, wherein fluid perfusion medium includes nutrients capable of sustaining the living tissue.

45. The system of claim 35, wherein the fluid perfusion medium is supplied to the bioreactor environment and waste is removed from the bioreactor environment continuously at a rate of 5 to 50 mL per day.

46. The system of claim 35, wherein the fluid perfusion medium is supplied to the bioreactor environment and waste is removed from the bioreactor environment at periodic intervals.

47. The system of claim 35, wherein at least one condition of the fluid perfusion medium in the perfusion bioreactor is measured.

48. The system of claim 47, wherein at least a portion of the fluid perfusion medium in the perfusion bioreactor is replaced when the condition meets a determined threshold value.

49. The system of claim 35, wherein a predetermined temperature is maintained within the environment defined by the first cooling chamber.

50. The system of claim 49, wherein the predetermined temperature is from about 0 to about 4 C.

51. The system of claim 35, wherein the second non-cooling chamber defines an

environment having a temperature controlled between about 10 and about 38 C.

52. The system of claim 35, wherein the first cooling chamber defines an environment having a controlled temperature of about 0 to 4 C and the second non-cooling chamber defines an environment at about room temperature.

53. The system of claim 35, wherein a cryoprotectant is not employed.

54. The system of claim 35, wherein the stored living tissue is not vitrified.

55. The system of claim 35, wherein the stored living tissue is not frozen.

56. A kit comprising

(i) a fluid impermeable outer container comprising a port in the lower portion adapted to be in fluid communication with a fluid conduit; a shelf, lip or protrusion on the interior to support an inner container (ii), and an opening in the upper portion adapted to receive and sealably engage a lid (iii);

(ii) a fluid permeable container adapted to fit within the outer container and allow a fluid perfusion medium to pass therethrough;

(iii) a lid comprising a port adapted to be in fluid communication with a fluid conduit, adapted to sealably engage the outer container and close the opening in the outer container; an optional opening for gas exchange; and optionally adapted to provide a gripping mechanism.

57. The kit of claim 56 further comprising a magnetic stir bar.

58. The kit of claim 56 further comprising a first fluid conduit and a fitment adapted to operatively engage the port in the outer container (i) and a second fluid conduit and a fitment adapted to operatively engage the port in the lid (iii).

59. The kit of claim 58 further comprising a container containing a fluid perfusion medium adapted to sustain and preserve living tissue when contained in the outer container (i) and adapted to operatively engage the second fluid conduit.