Stem cell secretome as a mechanism for restoring hair loss due to stress, particularly alopecia areata: narrative review

BACKGROUND: Living organisms are continuously exposed to multiple internal and external stimuli which may influence their emotional, psychological, and physical behaviors. Stress can modify brain structures, reduces functional memory and results in many diseases such as skin disorders like acne, psoriasis, telogen effluvium, and alopecia areata. In this review, we aim to discuss the effect of secretome on treating alopecia, especially alopecia areata. We will shed the light on the mechanism of action of the secretome in the recovery of hair loss and this by reviewing all reported in vitro and in vivo literature. MAIN BODY: Hair loss has been widely known to be enhanced by stressful events. Alopecia areata is one of the skin disorders which can be highly induced by neurogenic stress especially if the patient has a predisposed genetic background. This condition is an autoimmune disease where stress in this case activates the immune response to attack the body itself leading to hair cycle destruction. The currently available treatments include medicines, laser therapy, phototherapy, and alternative medicine therapies with little or no satisfactory results. Regenerative medicine is a new era in medicine showing promising results in treating many medical conditions including Alopecia. The therapeutic effects of stem cells are due to their paracrine and trophic effects which are due to their secretions (secretome). CONCLUSION: Stem cells should be more used as an alternative to conventional therapies due to their positive outcomes. More clinical trials on humans should be done to maximize the dose needed and type of stem cells that must be used to treat alopecia areata.