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.

Nailfold capillaroscopy alterations in androgenetic alopecia: A case–control study

Background: Androgenetic alopecia is considered to be an independent predictor of mortality from diabetes mellitus and heart disease. However, whether androgenetic alopecia causes changes in microcirculation is unknown. Objective: The objective of the study was to investigate whether alterations in nailfold capillaries occur in androgenetic alopecia patients. Methods: The nailfold capillaroscopy images of androgenetic alopecia patients and matched controls were collected and analyzed. Results: The frequencies of avascular areas, dilated, bushy and bizarre capillaries and capillary disorganization, nailfold capillaroscopy scores of 2 or scores both 2 and 3 were significantly higher in the androgenetic alopecia group than in the healthy controls (9.0% vs. 0%, 57.7% vs. 19.2%, 3.8% vs. 0%, 2.8% vs. 1.3%, 3.8% vs. 0%, 38.5% vs. 12.8% and 39.7% vs. 12.8%, respectively). Limitations: The results of this study may be biased on account of the limited sample size or the presence of an undiagnosed disease in participants which could alter the nailfold capillaries. Conclusion: Bushy, bizarre and dilated capillaries, capillary disorganization, avascular areas and nailfold capillaroscopy scores of 2 or 2 and 3 were more common in androgenetic alopecia patients than in healthy controls. These findings indicate that abnormalities in microcirculation may be involved in androgenetic alopecia.