University of Alberta

Sertoli Technologies, Inc.

Ray V Rajotte

Alfred V Vasconcellos

Craig Reed Halberstadt

Paul Gores

Jonathan R Lakey

Garth L Warnock

Michael Flashner

C Budd Colby

Jonathan Rt Lakey

Richelle Hemendinger

Greg Korbutt

Jannette Dufour

A system for storing a plurality of cryopreservable samples is provided, comprising a liquid nitrogen Dewar flask having a substantially circular opening of diameter X defined therein, the Dewar flask containing therein a plurality of Dewar flask-compatible storage racks, each storage rack comprising at least one substantially rectangular container, having a first set of opposite sides in substantially perpendicular relationship with a second set of opposite sides, the first set of opposite sides and the second set of opposite sides defining an inner space therebetween, and a plurality of strips, located in the inner space and each in contact with at least one side, formed in substantially parallel relationship with the first set of opposite sides, the plurality of strips forming a plurality of storage slots in the inner space, wherein at least one of the plurality of storage slots contains a cassette containing therein a cryopreservable sample. The plurality of storage racks are arranged in the Dewar flask such that a circle intersecting at least two of the plurality of storage racks located in the Dewar flask has a diameter which is greater than the diameter X of the opening. A method of storing cryopreservable samples is also provided.

Dewar flask-compatible storage system and method of use thereof

A method for bulk cryopreservation of biological material includes the steps of providing a flexible container, such as a freezer bag, containing biological material that is treated with a cryoprotectant and freezing the biological material to below -100.degree. C. and preferably below -196.degree. C. for deep freeze long-term storage. In the preferred embodiment, the bag is placed in a holder that maintains the cross-sectional area of the bag essentially constant and small enough (e.g., about 5 mm width to facilitate uniform heat transfer to and from all regions the bag. This facilitates uniform nucleation of the biological material after supercooling which enables controlled and uniform slow cooling through from about -7.5.degree. C. to a temperature in the range of about -40.degree. C. to -80.degree. C., thereby maintaining the viability of the cells. The single freezer bag method facilitates cryopreservation of large amounts of material, such as entire preparations of isolated islets, as compared to conventional multiple tube cryopreservation protocols and yields similar or improved recovery. In addition, the single freezer bag method reduces the risk of cross-contamination, a problem when adding and withdrawing material form multiple tubes before, during and after the cryopreservation freeze-thaw cycle. The bag construction also reduces the risk of freezing medium (e.g., liquid nitrogen) seeping into the bag and causing the bag to burst when thawing the material. The present invention is directed, in particular, to the cryopreservation of encapsulated islets in a flexible container wherein the container thickness during freezing is maintained around 5 mm. The freezing may also be accomplished by supercooling the encapsulated islets and inducing ice nucleation.

Methods for bulk cryopreservation encapsulated islets

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Edmonton, Canada

Ray V Rajotte