Study On Artificial Dermal Papilla Inducing To Form Tissue Engineered Hair Follicle In Vivo And Vitro

Background:Tissue engineering is to apply the principle of biology and engineering, to study and exploit substitute which can repair, maintain, and improve the function of injured tissue. The method is to put high concentration, functional related viable cells cultured in vitro in extracelluar matrix which is natural or artificial synthesis, and then transplant them to animal, to reach the aim that forming new functional tissues. Utilizing the technique of tissue engineering to form tissue engineered follicle, which provide infinite material for clinical therapy of hairless.Dermal papilla is located in the bulb of follicle, it is composed of a cluster specialized dermal fibroblast-dermal papilla cells(DPs). Dermal papilla cells make inducing, manipulating and regulating morphogenesis of hair follicle and maintaining growth and cycle of hair follicle come true beyond a series of signal molecular, signal way and the interaction of signal molecular of epithelial-mesenchymal interactions. Dermal papilla cells being cultured in vitro to form engineered tissue dermal papilla is the key step of reconstructing hair follicle.In our experiment, we first applied the technique of engineering and microencapsulation to reconstruct "artificial dermal papilla", and transplant it to hypodermis in the dorsal skin of the nude mice, which induce hair growth of the local skin. In histological section, we observed: fully developed hair follicle. At the same time, we study on "artificial dermal papilla "co-culturing with epithelial stem cells in vitro initially, and study on the possibility of it inducing the latters to differentiate to hair follicle keratinocytes. Objective:To produce human scalp dermal papilla cells micocapsules and observe the induction of the microencapsulated dermal papilla cells in the regeneration of hair follicle on dorsal skin of nude mice, and the possibility of its inducing epithelial stem cells to differentiate to hair follicle keratinocyte. Methods:1.Human scalp hair DPs were isolated by means of the collagenase digestive technique. The DPs were encapsulated with alginate-polylysine-alginate(APA). 2.The encapsulated DPs were embedded in collagen gel and implanted into the dorsal skin ofnude mice, empty microcapsules were implanted as control. Observe the hair growth of the spot of transplanted, and exam the structure of the hair follicles by histological examination. 3.Utilize the character of epithelial stem cells adhering to IV collagen to isolate and culture epithelial stem cells.4.Put epithelial stem cells co-culture with artificial dermal papilla, observe the growth and differentiation of epithelial stem cells, and exam the variety of the morphology structure and the cells' marker by histological examination. Results:LAP A microcapsules are two fold and hollow capsules, the diameter is about 400-500 U m, the surface is smooth, and the cells in the capsules are viable.2.1n four weeks following transplantation, white, thick, and regular distributed hair were visible in the dorsal skin of nude mice. In histological section, we observed: fully developed hair follicle. In control groups, the xenotransplantation of free DPs or empty microcapsules failed to elicit the same response.3.The cells which can adhere to IV collagen quickly, accrete like lamellar and aggregation, integrin P 1 and keratin 19 stain active, there are brown bead seen in the cytoplasm.4.Epithelial stem cells co-culture with microencapsulated human dermal papilla in four weeks, can be seen that its cell body enlarged , nucleus decreased and the ratio of nucleus to plasm decreased, keratin 17 stain positive, but there are no any structure of hair follicle seen. Conclusion:1. microencapsuled DPs which is of aggregative behavior could maintain the inductive properties of the regeneration of hair follicles, and the inductive properties can act across species between human and mouse.2.microencapsulated dermal papilla cells have the ability of inducing epithelial stem cells which are co-culture with them to differentiate. And epithelial stem cells have the potency of differentiating to hair follicle keratinocytes.