Control of hair growth and follicle size by VEGF-mediated angiogenesis.
Level 5 - mechanism / opinion, no new human data
Preclinical animal model and in vitro tissue culture study
PubMed 11181640 · doi:10.1172/JCI11317
What was done
The authors quantified cyclic changes in perifollicular vascularization during hair cycle phases (anagen, catagen, telogen) in mice and evaluated VEGF mRNA expression in outer root sheath follicular keratinocytes versus dermal papilla cells. They examined hair regrowth after depilation, perifollicular vascularization, and follicle/shaft dimensions in transgenic mice overexpressing VEGF in outer root sheath keratinocytes, as well as in mice receiving systemic neutralizing anti-VEGF antibodies. They also tested VEGF supplementation and blockade in mouse vibrissa organ cultures lacking a functional vascular network.
What was found
Perifollicular vascularization increased during anagen and regressed during catagen and telogen, coinciding spatially and temporally with VEGF mRNA upregulation in outer root sheath keratinocytes (not dermal papilla cells). Transgenic VEGF overexpression increased perifollicular vascularization, accelerated post-depilation hair regrowth, and increased hair follicle and shaft size. Conversely, systemic anti-VEGF antibody treatment retarded hair growth and reduced follicle size. In avascular vibrissa organ cultures, VEGF manipulation showed no effect. The abstract reports qualitative directions of effect without exact numerical measurements or confidence intervals.
Why it matters
This study provides mechanistic evidence that hair follicle growth and cycling are regulated by perifollicular angiogenesis mediated by keratinocyte-derived VEGF.
Limits
The study is restricted to murine in vivo and ex vivo models, and findings may not directly translate to human hair cycling or alopecia. Sample sizes, quantitative effect sizes, and statistical variance metrics are not reported in the abstract.
Cited by
- supports A mouse study indicates that reduced blood flow to hair follicles contributes to hair loss.