PEER-REVIEW | HAIR GROWTH | Figure 3 Variation in caliber
0.0440 0.0430 0.0420 0.0410
0.0401
0.0400 0.0390 0.0380 0.0370
Treated
Before treatment Control
0.0397 0.0395
TREATED VS CONTROL 0.0437
0.0423
Kingston et al, EGF serves as a biologic switch for entering and leaving the anagen phase11
. IGF slows down apoptosis. IGF-1 acts as a signal in
mitotic different cell lines and protects cells apoptosis. IGF-1 regulates the expression of a powerful messenger cellular level, which is anti-apoptotic and capable of preventing the cell death12
. FGF stimulates the proliferation and differentiation of 0.0409
keratinocytes and endothelial cells. It is over-expressed in then anagen phase and then less so from stage VI of anagen13
. NGF strongly stimulates hair growth and slows down
apoptosis. NGF has a modulating effect on the hair depending on the receptor with which it interacts: at the level of the outer root sheath, the complex NGF TrkA stimulates proliferation keratinocytes, while NGFj p75NTR promotes apoptosis, the regression of the follicle, and inhibits the growth of hair12
. 4 Months 8 Months During anagen–catagen transition, increased PDGFs stimulate the growth of dermal mesenchyme.
PDGF signals are involved in both epidermis–follicle interaction and the dermal mesenchyme interaction required for hair canal formation and the growth of dermal mesenchyme, respectively5
. VEGF belongs to a family of powerful Vascular endothelial
growth factors with action on mitotic cells and the endothelial cells of blood vessels, and increases vascular permeability. The hair follicle is an avascular structure, the growth of which depends on the vessels and capillaries that form the vascular plexus in the dermal papilla. Yano et al6 identified VEGF as a significant mediator of hair follicle growth and cycling, providing the first direct evidence that improved follicle vascularisation promotes hair growth, as well as increasing follicle and hair size. In a trial of 104 patients receiving hair transplants, have shown, by means of confocal
Rinaldi et al7
microscopy, that the up-stimulation of VEGF through adenosine receptors induces significant changes in the average diameter of the scalp’s perifollicular vessels compared with placebo, and an elongation of the transplanted follicles in the anagen phase. Further studies have shown that the up-stimulation of adenosine receptors contributes to the growth of hair through direct stimulation of the production of VEGF by the dermal papilla8, 9
. EGF stimulates mitosis on epithelial cells and
fibroblasts, and improves the ratio of anagen. EGF inhibits the entry in the catagen phase, promoting the anagen phase10
. EGF signals control the orientation and
elongation of follicles, probably attributable to its effect on the proliferation of basal keratinocytes and of cells that comprise the outer root sheath of hair. High doses of EGF can induce regression of the follicle. As proposed by
24 ❚ June 2013 |
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growth factor belongs to a family of powerful growth factors with action on mitotic cells and the endothelial cells of blood vessels, and increases vascular permeability.
neuroimmune communication leads to perifollicular neurogenic inflammation, apoptosis in hair follicles, and premature catagen development. A survey of the literature on key candidates in skin–stress responses reveals that not only noradrenaline, the prominent signaling molecule of the sympathetic stress response, but also NGF, act as stress mediators. This is certainly one of the best ways in which to explain the correlation between stress and hair-loss14
.
Literature review With regard to evaluations of the use of PRP in androgenic alopecia, there are three main studies currently available. Sorbellini et al15
carried out an in vitro study on 50 patients.
Twelve follicles were taken from each patient, of which four follicles were placed in PRP, four in Ringer’s solution, and four in a standard solution. The authors then measured mitotic activity. The results showed a significant increase of mitotic activity and a reduction in the apoptotic process in the PRP group. The purpose of Takikawa et al’s study16
was to see
whether there is a difference between simple PRP injection and PRP containing delteparine. Delteparine is a protein carrier for growth factors in PRP. The study
Figure 4 (A) Before and (B) 8 months after one session of platelet-rich plasma treatment
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