Scalp extracellular matrix (Scalp ECM)

The scalp extracellular matrix (ECM) is a complex, non-cellular network of proteins and polysaccharides that provides the essential structural scaffold for hair follicles and surrounding dermal tissues. It is primarily composed of various collagen types, elastin, and proteoglycans, which together regulate the mechanical properties of the scalp and facilitate cell-to-matrix signaling (Abhijit et al., 2022). In healthy scalp tissue, the ECM undergoes constant remodeling to support the different phases of the hair growth cycle, particularly during the transition between anagen and catagen. However, pathological changes in ECM composition, such as the accumulation of dense collagen bundles known as perifollicular fibrosis, are closely associated with the progression of androgenetic alopecia and other scarring alopecias (Kligman, 1988; Jaworsky et al., 1992). These fibrotic changes increase scalp stiffness and are thought to physically constrict the hair follicle, contributing to its miniaturization and eventual loss of function. Therapeutic interventions targeting the scalp ECM aim to restore its elasticity and healthy composition by stimulating fibroblast activity, inhibiting matrix metalloproteinases (MMPs), or modulating fibrotic signaling pathways like TGF-beta (Philpott et al., 1996; Shwartz et al., 2020). Drugs such as minoxidil and various collagen-stimulating agents are often employed to modify this environment and promote a more favorable niche for hair regrowth (Murad et al., 1994).

Other names

Scalp collagenDermal extracellular matrixPerifollicular matrixFollicular connective tissue sheath

Modulation of the scalp extracellular matrix involves the stimulation of dermal fibroblasts to synthesize high-quality Type I and Type III collagen, the inhibition of matrix metalloproteinases (MMPs) to prevent excessive protein degradation, and the antagonism of pro-fibrotic signaling molecules such as TGF-beta1 to reduce perifollicular fibrosis.