Enzymatic dissociation of keratinocytes from human skin biopsies for <i>in vitro</i> cell propagation

Abstract

Four techniques for dissociation of skin biopsies were compared to identify the method of choice for optimal expansion of isolated keratinocytes. Equivalent biopsies were obtained from 4 healthy human subjects and each divided into four parts. One part was minced and placed in a trypsinizing flask containing 0.05% trypsin and 0.01% ethylenediaminetetraacetic acid (EDTA). Released cells were harvested hourly. With the other parts, the epidermis was separated from the dermis after treatment with 0.5 mg/nml thermolysin, 2.5 mg/ml Dispase, or 0.17% trypsin and the epidermal portions were minced and incubated for 1 h in trypsin:EDTA. The cells were cocultivated with irradiated 3T3 fibroblasts to study the keratinocytes proliferative capacity. Freshly isolated cells were immunostained with anti-vimentin antibodies or grown in fibroblast-supportive conditions to detect the presence of human dermal fibroblasts. The mean number of cells dissociated per cm2 biopsy was higher after trypsin:EDTA digestion of a dermis-containing biopsy using a trypsinizing flask (4.0x 10(6) cells/cm2) compared to a biopsy where dermis-epidermis had been separated by thermolysin (2.8x 10(6) cells/cm2), Dispase (2.3x 10(6) cells/cm2) or trypsin (1.1 x 10(6) cells/cm2). Between 0.5% and 4% of the cells dissociated from a dermis-containing biopsy were human fibroblasts. This comprised more than twice the number of fibroblasts obtained by using epidermal/dermal split techniques. The proliferative capacity in primary and secondary culture was higher in cells isolated by trypsin:EDTA incubation in the trypsinizing flask or after epidermal-dermal separation using thermolysin, suggesting that Dispase or trypsin may have a more detrimental effect on the isolated keratinocytes. Our results show that dissociating the cells by trypsin:EDTA incubation in a trypsinizing flask or after epidermal-dermal separation using thermolysin, are preferable methods for isolating keratinocytes from human skin.