Note: Among cell populations of HF the folloving are the most important:
- Cells of epithelial origin: matrix trichocytes [M] and ORS [outer root sheath] cells.
- Cells of dermal origin: DP fibroblasts and dermal sheath [DS] fibroblasts.
The last play in HF predominantly regulation role, while the former represent mitotically active populations.
This model can help us to find answers to the following questions:
Is DP potential enough to control all stages of ORS cells proliferation and differentiation, so that ORS can give rise to M cells?
During telogen/early anagen of growth cycle DP is in the close vicinity with bulge region of ORS. During this period DP induct bulge region stem cells’ proliferation and further migration downward to become M cells. What are the details of this process?
Due to the fact, that practical realization of this model is technically difficult, in literature only few articles were founded.
1. Pure cultures of DP and ORS cells were obtained from crude fractions of human scalp HFs, that were prior incubated in dispase solution. These cells were than injected together into the subcutis of nude mice or were implanted onto the chorioallantoic membrane of 9 day old chicken embryos.
In first case, 3 weeks after at histology the mixtures of early-passage dermal papilla cells and outer root sheath form epidermal cysts, surrounded by layers of fibrous tissue.
In second case a keratinized mass lying on the chorionic epithelium with or without smaller similar masses in the chorioallantoic membrane was found in 8 days. No hair follicle-like structure could be found.
No hair follicle-like structure could be found.
CHIU H.C., CHANG C.H., JEE S.H., CHANG C.C., WU Y.C., human dermal papilla cells & outer root sheath cells: no follicular differentiation in nude mice & chicken embryos. // J. Formos. Med. Assoc., vol.9399)., p.770-775., 1994
1. In vitro, when plucked follicles were cultured together with isolated DP in a collagen gel matrix, ORS cells grew more rapidly and actively than without the DP. They form spikes toward DPs. Cultured DPs cells also activated the colony growth of ORS cells in vitro. These results show us, that DP is not capable enough to induct hair-like structures from ORS cells in vitro.
ARASE. S ., SADAMOTO. Y ., et al. Co-culture of human hair follicles & dermal papillae in a collagen matrix . // J. Dermatol . 1990 Vol 17(11) . p 667-676 ,& Annals of the New York academy of sciences . vol 642, p 454
ARASE. S., SHIKIJI. T., Experimental approaches for the reconstitution of hair in vitro . // Skin Pharmacol., 1994 vol.7 , p.12-15.
2. 3-D cultures, based on collagen gels or matrigel DP and ORS cells together gave rise to spheroid bodies with epidermal type of differentiation and to spike-like projectors without no apparent type of terminal differentiation. Authors believed it to be trichocytes type of differentiation. But this was not confirmed.
JAHODA C.A., REYNOLDS A.J., Dermal-epidermal interaction – follicle-derived cell population in the study of hair growth mechanisms. // J. Invest. Dermatol., vol. 101., p.33s-38s., 1993
3. When ORS and DP [from facial region] cells were cultured in vitro without direct contact between 2 cell populations and in the present of testosterone – ORS cells’ proliferation rates become higher. This effect was absent in case of DP fibroblasts from occipital region and in the absent of DP cells.
ITAMI S., KURATA S., SONODA T., TAKAYASU S., interaction between dermal papilla cells & follicular epithelial cells in vitro: effect of androgen. // Br. J. Dermatol., vol.132(4)., p.527-532., 1995 |
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