Stem Cell-Based Therapies for Hair Loss: What is the Evidence from a Clinical Perspective?

Abstract

Introduction: Stem cell-based therapies, especially those based on stem cell-derived conditioned medium (CM) are being widely explored in the clinical setting as a promising therapy for hair follicle regeneration. Based upon the pathogenesis of androgenetic alopecia (AGA) where the ability of hair follicle stem cells to differentiate into progenitors is disrupted, the goal of stem cell-derived CM is to restore the signals responsible for hair follicle stem cell activation. In this chapter we provide an up-to-date review of the stem cell-based technologies being used for hair regeneration, including outcomes of the clinical studies, therapeutic potential and possible mechanisms of action. Methods: For the selection of literature cited we used Pubmed database and ClinicalTrials.gov. The keywords used in the Pubmed and ClinicalTrials.gov. research were: alopecia, androgenetic alopecia; hair loss; hair growth; stem cell; stem cell therapy; platelet-rich plasma (PRP); stromal vascular fraction cells (SVFs); cell-free therapy; secretome; stem cell conditioned media (CM); mesenchymal stem cell exosomes; adipose-derived exosomes; clinical trials. Results: The use of PRP for the treatment of AGA has received considerable attention, but the lack of standard protocols (various centrifugation methods, platelet concentrations obtained, whether or not activators are added, etc.) has resulted in conflicting clinical outcomes. Several studies using SVF or stem cells show improvement in hair density in AGA patients, but need to be validated with more rigorous randomized placebo-controlled studies. Recently, many clinical studies have shown positive effects of stem cell CM on hair regeneration. Adipose stem cell derived-CM including growth factors and cytokines, enhances hair thickness and hair density, stimulates the transition to anagen, and promotes dermal papilla cell proliferation via activation of both Erk and Akt signaling pathways. Conclusion: The role of stem cell-based therapies in hair loss disorders is still in its infancy. Due to the some limitations of stem cell therapies the use of the stem cell secretome rather than stem cells themselves is emerging as a new alternative to hair loss treatment because of its efficacy in hair growth while avoiding potential risks of cell-based therapies. Overall, more randomized controlled, double-blind studies with larger sample sizes, objective evaluation methodologies and longer follow-up periods, as well as improved delivery systems are needed to evaluate and confirm the clear-cut benefits of stem cells and stem cell derived CM in the treatment of hair loss.KeywordsAlopeciaAndrogenetic alopeciaHair lossHair growthStem cellStem cell therapyPlatelet-rich plasma (PRP)Stromal vascular fraction cells (SVFs)Cell-free therapySecretomeStem cell conditioned mediaMesenchymal stem cell exososomesAdipose-derived exososomesClinical trials