Stem cell markers of the human hair follicle- characterization of a tissue engineered reconstruct basedon plucked hairs compared to human scalp

摘要

In patients suffering from therapy-resistantwounds, transplantation with split-thicknessskin grafts is hampered because of the limitedavailability of donor skin as well asmechanical long-term stability of the grafts.Alternative tissue engineered concepts(EpiDexO) use the hair follicle as origin forthe transplantation of follicular keratinocyteswhich are presumed to correspond to stemcells of the outer root sheath, however; had notyet been characterized upon their stem cellproperties.Material and Methods:Biopsies from human scalp were characterizedfor the expression of stem cell markers,previously identified in the murine hairfollicle. Keratinocytes were isolated andexpanded from human plucked hair follicles,according to the EpiDexO-protocol. Theexpression of keratinocyte precursor cells aswell as differentiation markers were analyzedimmunohistochemically in multilayered sheetsas well as in primary and serial cultures offollicular keratinocytes. By clonality assays,clonogenic potential of serial cultures wasinvestigated morphologically as well asquantitatively.Results:We could identify cytokeratin 15 (CK15),follistatin, and CD200 as markers for bulge-stem cells of the scalp hair follicle (however,not CD34, nestin, and cytokeratin 19),transferrin and p63 as markers for transientamplifying cells. In EpiDexO-sheetsexpression of CK15, follistatin, s1-integrin,transferrin, and p63 could be identifiedaccording to normal human epidermis.However, during serial culture, number ofholoclones diminished and CK15 was almostcompletely lost within the secondary passage.Conclusions:Follicular keratinocytes seem to be anappropriate origin to transplant keratinocyteprecursor cells. However, mechanisms shouldbe identified to enhance stem cell pool of suchtransplantation concepts.