Effect of alexandrite laser treatment for hair removal in Tibet mini-pigs / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the histological and ultrastructural changes of the skin and hair follicles following hair removal by alexandrite laser in Tibet mini-pigs.</p><p><b>METHODS</b>Twelve healthy Tibet mini-pigs with dark hair were treated with alexandrite laser for hair removal. The skin specimens were taken immediately and at 1 h and 1, 3, 5, 10, 15, 30, 60 days after the laser treatment for observation under optical and transmission electron microscope.</p><p><b>RESULTS</b>Laser hair removal resulted in extensive coagulation necrosis, carbonization and falling of the subcutaneous hair shafts, and some of the cells in the outer root sheath and hair bulb underwent degenerative and necrotic changes. One hour after laser treatment, the cells in the outer root sheath and bulb exhibited nuclear condensation, fragmentation and or karyolysis characteristic of cell apoptosis. The cell apoptosis reached the peak level on day 3 after the laser exposure, accompanied by endothelial degeneration in the hair papilla vessels, edema and lymphocyte infiltration in the dermal tissues. Tissue reaction and inflammation were relieved on day 5, and the dermal tissue and follicles recovered their normal structures on day 10. At 60 days after the treatment, the hair follicles decreased markedly but the structure of the residue follicles remained normal.</p><p><b>CONCLUSION</b>Alexandrite laser exposure results in selective destruction of the follicles by inducing direct coagulation and cell apoptosis to achieve permanent hair removal. Tibet mini-pigs with black hair can be used as the animal model of clinical laser hair removal.</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>