DIFFERENTIATION AND POLYPEPTIDE EXPRESSION IN HUMAN PAPILLA AND DERMAL FIBROBLASTS INVITRO

Proliferation and differentiation of human scalp hair follicle PaPilla fibroblasts (PF) in the anagenic stage of development and of neighbor ing dermal fibroblasts (DF) of the same donor were studied with stem c ell system-specific methods in primary and secondary populations in in vitro systems. Both populations differentiate along the sequence of m itotic fibroblasts (MF) MF I-MF II-MF III and postmitotic fibroblasts (PMF) PMF IV-PMF V-PMF VI-PMF VIIa/PMF VIIb, as described for fibrobla st stem cell systems in general elsewhere (Bayreuther et al., Mutat. R es. 256, 233-242 (1991)). PF and DF populations are distinguished by a number of cell-biological parameters, like population dynamics, maxim al cumulative population doublings (CPD), changes in cell type frequen cies, changes in cloning efficiency as a function of the CPD level (CP DL) of mitotic mass population, in addition by distinct changes of cel l type frequencies of postmitotic fibroblasts as a function of the dur ation of maintenance of postmitotic fibroblast population in stationar y culture. Primary and secondary PFs express cell type-specific high m olecular weight cellular polypeptides in the M(r) range of 190 to 270 x 10(3) and/or secrete cell type-specific low molecular weight polypep tides in the M(r) range of 27 to 28 x 10(3) as revealed by two-dimensi onal gel electrophoresis of [S-35]methionine-labeled and [C-14]proline -labeled polypeptides. These polypeptides are not expressed in the cor responding primary or secondary DF cell types. The expression of speci fic proteins in primary and secondary PF in vitro may correspond to sp ecific functions of PF in vivo.