Objective To provide theoretical evidence for clinical application of the epidermal stem cells after an investigation on changes of the epidermal stem cells during the survival process after the fullthickness skin autograft. Methods On the backs of 42 Wistar rats, orthotopic transplantation models (1.5 cm×1.5 cm) of the fullthickness skin autograft were made. According to the time of the specimen taking, at 1, 3, 5, 7, 14, 21 and 30 days after operation, the rats were randomly divided in 7 groups (Groups 1-7). Specimens taken in each group before operation were used as controls. At each time point, the gross observation was made on the transplanted skin flaps, from which the skin tissues were harvested at each time point before and after operation. The routine pathological and the immunohistochemical examinations were performed on the specimens, which were stained by HE and were observed for immunohistochemical changes and the changes in the cells positive for integrinβ-1 and p63. Results All the fullthickness skin autografts survived 3 days after operation except the skin autograft in 1 rat in both Group 5 and Group 6, which was infected around the transplanted skin flap. In Groups 1-4, cell edema, inflammatory cell infiltration, and increased fibrocytes were observed. In Groups 5-7, the maturity degree of the epithelial cells became higher and higher, and the fibrocyte proportion was lowered. In each group the cell positivity rate for integrin β1 was lower than the cell positivity rate for p63. The positive cells were arranged in disorder, distributed into the layers of the epidermis and gradually concentrated in the basal layer of the epidermis and the bulge of the folliculus pili. The positive cells were also found in the other layers of the epidermis.The positive cells were gradually decreased in number, and reached the lowest level in Group 2. There was a significant difference in the above variables in Groups 1,2,3,5,6 and 7 between before and after operations (P＜0.05). Conclusion During the survival process of the fullthickness skin autograft, the proportion of theepidermal stem cells is gradually decreased at first; Then, the proportion isgradually increased, even beyond the normal level; finally, the proportion is decreased again. The distribution of the epidermal stem cells appear in disorder, almost distributed in the layers of the epidermis; finally, the almost normal distribution can be found.
Objective To detect the expression of melanocortin 1 receptor (MC-1R) and the melanin contents in human skin autografts and the normal skin, to elucide the role of MC-1R in hyperpigmented process of skin autografts. Methods Skin autografts and normal skin samples were obtained from skin graft on neck who need reoperation to release contractures after 1 year of operations. Immunohistochemical technique was performed to detect the expression and distribution of MC-1R in skin autografts(include full thickenss skin autografts, medium thickness skin autografts, and razorthin skin autografts) and normal skin respectively. MassonFontana staining technique was performedto detect the melanin contents in all sorts specimens respectively. Results The expression of MC-1R was located on cell membrane and cytoplasm of melanocyte and keratinocyte in epidermal. The expression of MC-1R in most skin autografts was much ber than that of control normal skins; the thinnerskin autografts were, the more obvious expressions of MC-1R in skin autografts were. The expressions of MC-1R in all sorts of skinautografts were of significant differences compared with that in normal skins(P＜0.01); the expression of MC-1R in normal skin of donor area was no significant differences compared with normal skin around recipient area(P＞0.01). The contents of melanin in skin autografts were increased obviously and there were significantdifferences compared with that in normal skins(P＜0.01); the contents of melanin among all sorts of skin autografts were of significant differences (P＜0.01). The thinner skin autografts were, the more melanin contents in skin autografts. The expression of MC-1R was positively correlated with the contents ofmelanin in epidermis. Conclusion The expression of MC-1R in skin autografts is significantly higher than that in normal skin and is correlated positively with the contents of melanin in skin autografts. Overexpression of MC-1R may play an important role in hyperpigmented process of skin autografts.
Objective To discuss the expression of α-melanocyte-stimulating hormone(α-MSH) mRNA in human medium thickness skin autografts and to investigatethe role of αMSH in hyperpigmented process of skin autografts. Methods The samples were from medium thickness skin autografts on neck of the patients after 1 year of surgery. The size of sample was about 1.0 cm×0.5 cm. RT-PCR technique was performed to detect the expression of α-MSH mRNA in medium thickness skinautografts and normal skin respectively. Masson-Fontana stain technique was performed to detect the contents of melanin in medium thickness skin autografts andnormal skin epidermis respectively. Results The expression ofα-MSH mRNA in medium thickness skin autografts was much ber than that in control normal skin, showing statistically significant difference (P＜0.01). The expression of α-MSH/β2-microglobulin mRNA in normal skin of donor area was no statistically significant differences compared with normal skin around recipient area. The contents of melaninin medium thickness skin autografts epidermis obviously increased when compared with that of control normal skin. The expression of α-MSH mRNA was positive correlated with the contents of melanin in epidermis. Conclusion The above results indicate that the expression of α-MSH increases greater in medium thicknessskin autografts than in cortrol samples and was correlated with the pigmentation of skin autografts. Overexpression of α-MSH may play an important role in hyperpigmented process of skin autografts.