Patent ID: 7811819

Claim:
A method for the cryopreservation of human embryonic stem cells, the method comprising: partially dissociating an in vitro culture of human embryonic stem cells to provide a population of cell aggregates; resuspending said cell aggregates in a freezing medium comprising from about 5% to about 15% cyroprotectant; placing said resuspended cell aggregates in a closed container for freezing; cooling the container to a temperature just below freezing and inducing ice crystal formation of the freezing medium; slow cooling said resuspended cell aggregates at a rate not faster than about −2° C./min to a temperature of not higher than about −30° C., followed by a rapid cooling to not higher than about −80° C., to provide a cryopreserved sample; wherein upon thawing, the viability of cell aggregates in said cryopreserved sample is at least about 50%.