Cryopreservation of human embryonic stem cells with a new bulk vitrification method

To increase the manipulation efficiency and storage capability of vitrified human embryonic stem cells, a new bulk vitrification method was established using transformed cryovials. This method vitrified a large number of cell clumps, as opposed to those cryopreserved by a slow-freezing method with conventional cryovials at one time (round). After warming, vitrified human embryonic stem cells exhibited a much higher survival rate than the slow-freezing cells. The vitrified stem cells continued to express markers of pluripotency and formed teratomas in mice with severe combined immunodeficiency, confirming the pluripotency of vitrified-warmed human embryonic stem cell clumps. The new bulk vitrification method is superior to and more practical than the open pulled straw vitrification method and the slow-freezing method for the cryopreservation of human embryonic stem cells.