Impact of microenvironment on the growth of primary human epidermal cells

Although the conditions for in vitro cultivation of adult stem cells and tissue are easily standardized, little is known about the optimal conditions for biointegration after transfer of the tissue graft, playing an important role in the treatment of defects especially soft-tissue skin injuries. To examine the influence of the microenvironment, we investigated the doubling time of primary epithelial cells in relation to the culture medium. Serum from patients of different age groups (n = 15, <20 years; n = 9, >20 years; and fetal calf serum) was pooled independently of age and added to culture medium of epithelial cells from a skin donor (10%). Number of cells was counted in vitro after 1 and 4 days of cultivation using a photometric extinction test. Results were plotted using quotient for calculating cell proliferation ([T4 -T1]:T1). Statistical significance was calculated by Wilcoxon test. Highest proliferation rate was achieved by cultivating the cells in the heterological serum admixture. Homologous serum admixtures in the cell cultures of <20 donators yielded a significantly higher proliferation rate than adult serum (P < 0.01). High regenerative capacity of skin in children has, thus far, mainly been attributed to the high plasticity of the cellular structures. Our study shows for the first time that the age-dependent regenerative capacity in vitro is also influenced by age-dependent humoral factors. In vivo cells from older patients may thus be transferred into an altogether suboptimal microenvironment. Responsible humoral factors should be more closely examined to optimize the clinical management of cellular transplants.