Gharzi A, Reynolds AJ, Jahoda CAB. Plasticity of hair follicle dermal cells in wound healing and induction. Exp Dermatol 2003: 12: 126-136. # Blackwell Munksgaard, 2003 Abstract: The capacity of adult hair follicle dermal cells to participate in new follicle induction and regeneration, and to elicit responses from diverse epithelial partners, demonstrates a level of developmental promiscuity and influence far exceeding that of interfollicular fibroblasts. We have recently suggested that adult follicle dermal cells have extensive stem or progenitor cell activities, including an important role in skin dermal wound healing. Given that up to now tissue engineered skin equivalents have several deficiencies, including the absence of hair follicles, we investigated the capacity of follicle dermal cells to be incorporated into skin wounds; to form hair follicles in wound environments; and to create a hair follicle-derived skin equivalent. In our study, we implanted rat follicle dermal cells labelled with a vital dye into ear and body skin wounds. We found that they were incorporated into the new dermis in a manner similar to skin fibroblasts, but that lower follicle dermal sheath also assimilated into hair follicles. Using different combinations of follicle dermal cells and outer root sheath epithelial cells in punch biopsy wounds, we showed that new hair follicles were formed only with the inclusion of intact dermal papillae. Finally by combining follicle dermal sheath and outer root sheath cells in organotypic chambers, we created a skin equivalent with characteristic dermal and epidermal architecture and a normal basement membrane -the first skin to be produced entirely from hair follicle cells. These data support the hypothesis that follicle dermal cells may be important in wound healing and demonstrate their potential usefulness in human skin equivalents and skin substitutes. While we have made progress towards producing skin equivalents that contain follicles, we suggest that the failure of cultured dermal papilla cells to induce follicle formation in wounds illustrates the complex role the follicle dermis may play in skin. We believe that it demonstrates a genuine dichotomy of activity for follicle cells within skin.

Successful hair follicle organ culture has been established for some time, but hair growth in vitro is limited and generally terminates prematurely in comparison with in vivo. The reasons why growth stops in culture are as yet unknown. In this investigation, adult rat vibrissa follicles for which growth in culture is limited to about 10 d, were maintained in vitro for a minimum of 20 d after the hair shaft stopped growing. The pattern of fiber growth and long-term follicle pathology reflected the initial hair cycle stage at the time of isolation. Furthermore, there was evidence that a group of follicles put into culture when in late anagen were attempting to cycle in vitro. Microscopy showed that, in spite of widespread pathologic changes to the follicle epithelium, dermal cells in the follicle showed remarkable resilience. Their viability was confirmed when primary cell cultures were established from isolated dermal tissue. These cells labeled positively for alpha-smooth muscle actin, an established marker of hair follicle dermal cell phenotype in vitro. Moreover, isolated dermal tissue induced hair growth when implanted into inactivated hair follicles in vivo. These data confirm that the cessation in hair growth is not due to a loss of the inductive capacity in the dermal component. Long-term organ culture may provide opportunities to investigate factors that are expressed or lost during hair growth cessation. In addition it may be possible to develop this method further to obtain a reliable and predictable model of hair follicle cycling in vitro.

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BackgroundFinding the best dressing for a specific wound had continued from the past to present. The aim of this study was to evaluate the effect of encapsulated extract of Satureja khuzistanica in hydrogel alginate at wound healing.MethodsThirty-two male Wistar rats with a puncture wound in the back of the neck skin were divided randomly into four groups including a control group, Satureja khuzistanica-treated group, hydrogel alginate-treated group, and Satureja khuzistanica encapsulated in hydrogel alginate-treated group. Rats were treated for 22 days. The skin samples were taken on 3rd, 7th, 14th, and 22nd days after treatment for light microscopy. Results were analyzed in accordance with Kruskal-Wallis and Friedman test (for histopathology analysis) by using SPSS v.22 software.ResultsMacroscopically evaluations and measurement of wound size showed increased wound healing process in the treated groups. The complete improvement was created on the 14th day. The wound site was not observed on the 22nd day. But the wound site was observed on the 22nd day in the control group. Also, comparison of the percentage of wound healing between the treated and control groups on 3rd, 7th, 14th, and 22nd days showed a significant difference (p < 0.05). Comparison of the H&E stained sections in the studied groups showed that treated groups were effective on wound healing in comparison with the control group.ConclusionsEncapsulated extract of Satureja khuzistanica in hydrogel alginate may accelerate wound improvement and increase the rate of wound healing without scar formation.

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