The Biology and Genomics of Human Hair Follicles: A Focus on Androgenetic Alopecia

Abstract

Androgenetic alopecia is a highly prevalent condition mainly affecting men. This complex trait is related to aging and genetics; however, multiple other factors, for example, lifestyle, are also involved. Despite its prevalence, the underlying biology of androgenetic alopecia remains elusive, and thus advances in its treatment have been hindered. Herein, we review the functional anatomy of hair follicles and the cell signaling events that play a role in follicle cycling. We also discuss the pathology of androgenetic alopecia and the known molecular mechanisms underlying this condition. Additionally, we describe studies comparing the transcriptional differences in hair follicles between balding and non-balding scalp regions. Given the genetic contribution, we also discuss the most significant risk variants found to be associated with androgenetic alopecia. A more comprehensive understanding of this pathology may be generated through using multi-omics approaches.

Enhancing hair regeneration: Recent progress in tailoring nano-structured lipid carriers through surface modification strategies

“…Furthermore, it is important to note that not all therapies are universally applicable to all types of hair loss, and the results may differ depending on variables such as age, underlying health conditions, and individual reactions to therapy. It is crucial to conduct future research to uncover new therapeutic targets and improve treatment methods to overcome these constraints and enhance outcomes for individuals experiencing hair loss [ 11 , 12 , 33 ].…”

“…For topical products to be effective, they must penetrate the scalp barrier and reach the hair follicle with sufficient strength to achieve desired outcomes. Systemic medications may face challenges like metabolism, distribution, and unexpected side effects, reducing their effectiveness and tolerability [ 11 ].…”

“…Surface-functionalized NLCs can be customized to target hair follicles by incorporating specific ligands or bioactive compounds. This customization enhances the treatment’s effectiveness while minimizing potential negative effects [ 11 ]. Surface-altered NLCs show important characteristics that suggest they could improve hair growth treatment.…”

“…A larger surface area compared to volume and small particle size help drugs penetrate hair follicles effectively and deliver bioactive substances to specific targets. Surface modification additionally improves the targeting of follicles, guaranteeing the best possible deposition of drugs inside the microenvironment of the follicles [ 11 , 14 ]. NLCs offer a controlled release of bioactive substances by enclosing them within a lipid matrix; this allows prolonged medication retention at the target site and reduces the dosing frequency.…”

“…NLCs can be modified on their surface by targeting ligands, such as peptides or antibodies, allowing them to bind specifically to receptors in the cells of the hair follicle epithelium [ 16 ]. This interaction enhances the absorption and internalization of NLCs by the hair follicles, expanding the range of available medications and promoting specific therapeutic effects [ 11 , 17 ]. The lipid-based structure of NLCs provides natural protection for enclosed bioactive substances, shielding them from degradation and enzymatic metabolism.…”