BACKGROUND:Previous studies of our research group have confirmed that the texture of porcine reticular dermis at lateral ventral part is softer and has more extensibility than other parts. Therefore, it may serve as the raw material of xenogenic aceluar dermal matrix. However, its comparison with human and rat reticular dermis has not been reported systematicaly in aspects of histomorphology and material characterization. OBJECTIVE:To compare the reticular dermis from the lateral region of porcine abdomen and rat dorsal part with the reticular dermis from human in histology, biomechanics, molecular structure, thermal stability and other properties. METHODS:The reticular dermis samples were taken from adult human, the lateral region of porcine abdomen, the back of rats, for gross observation. Paraffin sections were observed by hematoxylin and eosin staining and sirius red staining under a light microscopy. The relevant data of micrograph were measured by imagine analysis software. These samples were also vacuum-freezing dried and rehydrated, and then their mechanical properties were tested with a electronic tensile machine to calculate the Young’s modulus. Some vacuum-freezing dried samples were powdered and detected by Fourier transform infrared spectrometer and simultaneous thermal analyzer. RESULTS AND CONCLUSION:There were no differences in colagen fiber bundle diameter of the reticular dermis from adult human and the lateral region of porcine abdomen, but the reticular dermis from the back of rats was thinner than that from adult human (P < 0.01). The gap between the reticular layer of the dermis of the lateral region of porcine abdomen was lower than that from adult human (P < 0.0.1); however, there was no difference in the gap between the reticular layers of the dermis of the rat back and adult human (P=0.17). Colagen fibers of porcine reticular dermis were arranged tightly in disorder; the content of type I colagen and ratio of type I/III colagen were higher than those in the reticular dermis from adult human (P < 0.05), but the content of type III colagen was less than that in the reticular dermis from adult human (P < 0.05). Contents of type I and III colagen and their ratio were similar between the reticular dermis of rats and adult human (P > 0.05). There was no significant difference in the Young’s modulus of the three kinds of reticular dermises. Hydrogen bonds involved in the reticular dermal colagen molecules ranged as folows: rats > swine > human. Rat reticular dermis has better thermal stability than that of swine and adult human.

OBJECTIVETo explore the influence of recombinant human growth hormone (rhGH) on the apoptosis and intestinal mucosal structure in severely scalded rats.

METHODSThirty male Wistar rats were randomly divided into three groups, i.e. control, scalding and rhGH groups. The rats in scalding and rhGH groups were inflicted with 25% TBSA III degree scalding on the back and immediately followed by intraperitoneal injection of dexamethasone (80 mg/kg). The scalded rats were administered with normal saline and rhGH (1.33 IU.kg(-1).d(-1)) since 2 postburn hours (PBHs), respectively in the last two groups. The changes of the apoptosis rate, the intestinal mucosal proliferative index (PI) and epithelial ultrastructure and the intestinal mucosal pathomorphology of the distal end of ileal mucosal tissue were observed on 30 and 96 PBHs.

RESULTSThe intestinal mucosa morphology and epithelia in scalding group were severely injured but were significantly ameliorated by rhGH to near those in control group. The PI in rhGH and scalding groups at 30 PBHs was evidently higher that that in control group (P < 0.05 - 0.01). But the PI exhibited no obvious difference between scalding and rhGH groups. While the PI in rhGH group at 96 PBHs was obviously higher than that in both scalding and control groups (P < 0.01). The intestinal mucosal epithelial apoptotic rate in scalding group was significantly higher than that in control group (P < 0.01), while that in rhGH group was evidently lower than that in scalding and control groups (P < 0.05 - 0.01).

CONCLUSIONrhGH could promote postburn intestinal mucosa epithelial proliferation in slow - action manner and inhibit intestinal mucosal epithelial apoptosis with rapid and obvious effects. As a result, the intestinal mucosal epithelial injury could be ameliorated by rhGH by means of its inhibiting roles and the normal morphological structure of intestinal mucosa was maintained ad hoc.

Animals ; Apoptosis ; Burns ; pathology ; Human Growth Hormone ; genetics ; pharmacology ; Intestinal Mucosa ; drug effects ; pathology ; Male ; Rats ; Rats, Wistar ; Recombinant Proteins ; pharmacology

Background: This study aims to investigate the effect of integrin β1 on wound healing induced by adipose-derived stem cells (ADSCs), as well as the corresponding mechanism. Methods: Integrin β1 was overexpressed in ADSCs. Thereafter, flow cytometry and transwell chambers technology were used to measure the endothelial-like differentiation (CD31 as a biomarker of endothelial cell) and cell migration, respectively. Western blot was used to detect the activation of PI3K/AKT, NF-κB and ERK signaling pathways. The effects of integrin β1 overexpression on healing time, healing rate and fibroblast number were further evaluated in the rat models of chronic refractory wound. Results: The overexpression of integrin β1 increased CD31+ endothelial-like cells (about 3.6-fold), promoted cell migration (about 1.9-fold) and enhanced the activation of PI3K (p-PI3K; about 2.1-fold) and AKT (p-AKT; about 2.2-fold). These effects were all weakened when PI3K/AKT pathway was inhibited by LY294002 treatment. In addition, the experiments in rat wound models showed that integrin β1 overexpression obviously shortened healing time (approximately 0.41-fold), increased healing rate (about 2.7-fold, 2.8-fold and 1.6-fold at day 7, 14 and 21) and increased the number of fibroblasts (approximately 3.1-fold at day 21). All of the above differences were statistically significant (p < 0.05). Conclusion Integrin β1 can promote the migration and endothelial-like differentiation of ADSCs by activating PI3K/AKT pathway and then enhance the function of ADSCs in promoting wound healing.