INTRODUCTION
Skin aging is clinically characterized by xerosis, rhytids, dyschromia, atrophy, and skin laxity. It is a complex process involving both intrinsic and extrinsic elements. Intrinsic factors are numerous and still under investigation. They include, but are not limited to, telomere shortening/instability, genomic instability/mutations, stem cell exhaustion, protein, and cellular damage, increased inflammation, cell senescence, and impaired intercellular communication.1,2 Extrinsic factors contributing to skin aging are also plentiful and most notably include UV exposure, smoking, and poor nutrition. Histologically and molecularly, aged skin is characterized by epidermal atrophy, flattening of the rete ridges, decreased dermal thickness, deterioration of elastic fibers, fragmented and thickened collagen fibrils, and an increase in the collagen III to collagen I ratio.1
Despite the myriad of tools now available for prevention and repair of aged skin such as injectable fillers, neuromodulators, laser, radiofrequency, ultrasound devices, and surgical procedures, cosmeceuticals remain a cornerstone of the market. Research over the past two decades has emerged supporting the use of stem cells, growth factors, peptides, and exosomes as key ingredients in topical anti-aging regimens.3,4 Despite promising data, variation in final product, impurities, and nonspecific targets plague these complex sources.4
Alpha- and beta-defensins are naturally occurring antimicrobial and healing molecules that represent a novel treatment modality for skin rejuvenation. Within the skin, stem cell niches exist in the epidermis and adnexal structures and are critically important to skin homeostasis and regeneration. Notably, leucine-rich repeat-containing G protein-coupled receptor 6 positive (Lgr6+) stem cells which reside above the hair bulge, often referred to as the skin's master stem cell, create the epidermis and appendages early in utero and maintain their multipotency after birth as they are able to differentiate into both epidermal and adnexal structures.5 In addition to their roles in innate immunity, deterring microbial colonization, and reducing paracellular permeability, defensins have been found to induce wound healing via the recruitment of these Lgr6+ stem cells.5
Despite the myriad of tools now available for prevention and repair of aged skin such as injectable fillers, neuromodulators, laser, radiofrequency, ultrasound devices, and surgical procedures, cosmeceuticals remain a cornerstone of the market. Research over the past two decades has emerged supporting the use of stem cells, growth factors, peptides, and exosomes as key ingredients in topical anti-aging regimens.3,4 Despite promising data, variation in final product, impurities, and nonspecific targets plague these complex sources.4
Alpha- and beta-defensins are naturally occurring antimicrobial and healing molecules that represent a novel treatment modality for skin rejuvenation. Within the skin, stem cell niches exist in the epidermis and adnexal structures and are critically important to skin homeostasis and regeneration. Notably, leucine-rich repeat-containing G protein-coupled receptor 6 positive (Lgr6+) stem cells which reside above the hair bulge, often referred to as the skin's master stem cell, create the epidermis and appendages early in utero and maintain their multipotency after birth as they are able to differentiate into both epidermal and adnexal structures.5 In addition to their roles in innate immunity, deterring microbial colonization, and reducing paracellular permeability, defensins have been found to induce wound healing via the recruitment of these Lgr6+ stem cells.5
