Variation of the HES concentration for the cryopreservation of keratinocytes in suspensions and in monolayers

It has recently been shown that keratinocytes, both in suspension and in mo nolayers, can be successfully cryopreserved with hydroxyethyl starch (HES) (6, 9). HES is a nontoxic biodegradable macromolecule which is clinically a pproved as a plasma expander and which has already been used for the cryopr eservation of red blood cells (10, 11). In this study we varied the HES con centration between 0 and 10 wt% in 2% steps for suspended cells and between 0, 4, 6, 8, and 10 wt% for monolayer cells in order to determine the effec t on the survival rate and metabolic activity after cryopreservation. The e xperiments with the suspended cells were performed both with and without NC S. Cryopreserved keratinocytes can be transplanted onto patients for the tr eatment of deep dermal burns and leg ulcers. In this study, we achieved a s urvival rate of 80% for the suspended cells (10 wt% HES, 3 degreesC/min) an d a survival rate of even 88% when the cells were cryopreserved as a monola yer using the same parameters. The addition of NCS did not improve the resu lts for the suspended cells significantly. (C) 2000 Academic Press.