Changes of hair papilla and its role in the growth cycle of the hair follicles / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes of hair dermal papilla and its regulatory role in the growth cycle of the hair follicles.</p><p><b>METHODS</b>Single hair follicles were isolated from surgical specimens of human scalp and cultured in Williams E medium. The growth of the hair follicle was measured and the morphology and structure of the dermal papilla in the different growth cycles were observed continuously.</p><p><b>RESULTS</b>The hair follicle could grow in the medium for 12 days at the average growth rate of 0.2-0.3 mm/day. The flat and round dermal papilla lay at the bottom of the hair bulb in the telogen and anagen stages. In the hair follicle with accelerated growth, the dermal papilla became elongated, loosened, and closely adhered to the hair matrix. In the catagen stage the dermal papilla shrunk, and became separated from the hair matrix. A new hair bulb was regenerated when the hair follicle was transected at a low level. The hair follicle stopped growing after transection at a higher position.</p><p><b>CONCLUSION</b>The hair dermal papilla is the essential for hair follicle growth, and plays an important role in regulating the hair growth cycle.</p>

Role of angiotensin II receptors in proliferation of fibroblast derived from human hypertrophic scars / 中华整形外科杂志

<p><b>OBJECTIVE</b>The present study was undertaken to observe the expression of angiotensin II (Ang II) type 1 (AT1) and type 2 (AT2) receptors in human hypertrophic scars, and explore their role in the proliferation of fibroblasts in human hypertrophic scars.</p><p><b>METHODS</b>The expression of both ATL and AT2 receptors in fibroblasts of hypertrophic scars was detected with immunohistochemical staining. Radioligand receptor binding assay and RT-PCR were used to determined expression level of AT1 and AT2 receptors in cultured fibroblasts derived from hypertrophic scars. DNA synthesis was examined in cultured fibroblasts of hypertrophic scars by measuring [3H]-TdR incorporation into fibroblasts.</p><p><b>RESULTS</b>Positive staining signals of both AT1 and AT2 receptors were found in fibroblasts of hypertrophic scars. Expression level of AT1 and AT2 receptors were (10.69 +/- 2.15) fmol/10(6) cells, (4.9 +/- 1.05) fmol/10(6) cells respectively in cultured fibroblasts derived from hypertrophic scars. RT-PCR showed the similar results. In cultured fibroblasts, Ang II stimulation significantly increased DNA synthesis (P < 0.05 vs negative control), which was inhibited by valsartan, an AT1 receptor blocker, but augmented by PD123319, an AT2 receptor antagonist. Valsartan or PD123319 alone did not influence the proliferation of fibroblasts derived from hypertrophic scars.</p><p><b>CONCLUSIONS</b>Both AT1 and AT2 receptors were expressed in the fibroblasts of hypertrophic scars, and Ang II regulates DNA synthesis in hypertrophic scar fibroblasts through a negative cross-talk between AT1 and AT2 receptors, which might contribute, at least partly to formation and maturation of human hypertrophic scars. The present study provides new insight into pathogenesis of hypertrophic scars.</p>