Tissue Engineering and Regeneration of the Human Hair Follicle in Androgenetic Alopecia: Literature Review

Androgenetic alopecia (AGA) is an androgen-dependent process and represents the most frequent non-scarring alopecia. Treatments for AGA do not always achieve a satisfactory result for the patient, and sometimes cause side effects that lead to discontinuation of treatment. AGA therapeutics currently includes topical and oral drugs, as well as follicular unit micro-transplantation techniques. Tissue engineering (TE) is postulated as one of the possible future solutions to the problem and aims to develop fully functional hair follicles that maintain their cyclic rhythm in a physiological manner. However, despite its great potential, reconstitution of fully functional hair follicles is still a challenge to overcome and the knowledge gained of the key processes in hair follicle morphogenesis and biology has not yet been translated into effective replacement therapies in clinical practice. To achieve this, it is necessary to research and develop new approaches, techniques and biomaterials. In this review, present and emerging hair follicle bioengineering strategies are evaluated. The current problems of these bioengineering techniques are discussed, as well as the advantages and disadvantages, and the future prospects for the field of TE and successful hair follicle regeneration.

Expression and distribution of EPHA4 and Ephrin A3 in Aohan fine-wool sheep skin

The objective of this study was to identify the expression and distribution of EPHA4 and Ephrin A3 genes in the development and morphogenesis of hair follicles in fine-wool sheep. The results could lay a theoretical basis for understanding the molecular mechanism that regulates hair follicle development. The skin of Aohan fine-wool sheep at different developmental stages (embryonic day 90, E90d, and 120, E120d, and postnatal day 1, B1d, and 30, B30d) were selected. Real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry were used to study the levels of mRNA and proteins, respectively. The RT-qPCR results showed that the mRNA expression level of EPHA4 at B1d was significantly lower than at E120d (p<0.01). The expression of Ephrin A3 at E120d was significantly higher than that at E90d and B1d (p<0.01). Immunohistochemical detection results showed that the level and localisation of EPHA4 and Ephrin A3 proteins had spatial and temporal specificity. EPHA4 expression in dermal papilla cells might be important for inducing Aohan fine-hair follicle regeneration and for controlling the properties of the hair. Ephrin A3 might play an important role in the redifferentiation of secondary hair follicles and might also be involved in the inhibition of apoptosis-related gene expression in hair follicles. The Ephrin A3 signalling pathway might accelerate the growth of fine-hair follicles and increase the density of hair follicles.

Dermoscopy of pilomatricoma: A case report with a review of the literature

Pilomatricoma is a benign tumor originating from hair follicle matrix cells and characterized by the presence of cutaneous and subcutaneous nodules up to 3.0 cm in diameter, usually on the head, neck, and upper extremities, rarely on the trunk and lower extremities. An eleven-year-old female with a painless, erythematous-purplish tumor of the back. A dermoscopic examination revealed irregular linear vessels, white structures, and structureless grayish-blue areas. Histological examination after excision confirmed the diagnosis of pilomatricoma. Dermoscopy may be a useful tool for improving the clinical recognition of pilomatricoma.