Asunto(s)
Folículo Piloso/metabolismo , Cabello/metabolismo , Queratinocitos/fisiología , Cuero Cabelludo/citología , Canales Catiónicos TRPM/metabolismo , Proliferación Celular , Células Cultivadas , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Voluntarios Sanos , Humanos , Factor I del Crecimiento Similar a la Insulina/genética , Masculino , Organogénesis , Transducción de Señal , Canales Catiónicos TRPM/genética , Factor de Crecimiento Transformador beta2/genéticaRESUMEN
The pilosebaceous unit (PSU) and the eccrine sweat gland (ESG) are classically described as completely independent skin appendages. However, careful inspection of scalp follicular units reveals that the secretory segment of the ESG spatially approximates the hair follicle in a position below the sebaceous gland and the insertion of the arrector pili muscle. Therefore, we propose here that, contrary to conventional wisdom, the PSU and the ESG should not be viewed in isolation, and may form instead, along with the arrector pili muscle and the apocrine gland (where present),one functional unit. For this, we suggest the more inclusive term of 'Hair Cluster' (HC). If confirmed, e.g. by 3D imaging techniques, the novel concept of a functional HC, whose individual components may communicate via secreted molecules and may share selected progenitor cell populations for HC repair/regeneration, has major physiological and pathological implications, which are briefly discussed.
Asunto(s)
Glándulas Ecrinas/anatomía & histología , Folículo Piloso/anatomía & histología , Cuero Cabelludo/anatomía & histología , Glándulas Apocrinas/anatomía & histología , Humanos , Músculo Liso/anatomía & histología , Cuero Cabelludo/fisiologíaRESUMEN
Compared to murine models, data on cells responsible for the homeostasis of human epidermis are scarce and often contradictory. Given the conflicting results and the availability of clinical grade protocols to purify CD34 cells from a given tissue, we pursued to phenotypically characterize human epidermal CD34+ population. After magnetic separation of whole skin CD34+ and CD34- cell fractions and selection for cells highly adherent to extracellular matrix, both CD34+/- fractions retained the ability to form a stratified epidermis in organotypic cultures and presented similar in vitro migratory phenotypes. However CD34- cells showed higher clonogenic potential and in vitro proliferative capacity. These results indicated that CD34- cell fraction contains stem/early progenitor cells, while CD34+ cells might be a transit-amplifying precursor for hair follicle (HF) sheath cells. The ability to isolate living cells using differential cell adhesion and surface markers provides an opportunity to study cells from different morphological regions of the HF.