Objective To evaluate the effect of tissue engineered skin with isogeneic cells on repairing skin defects in inbred rat model so as to provide relevant evidences for the clinical application. Methods The skins of newborn inbred F344 rats were harvested and treated with Dispase trypsin to isolate the epidermal cells. The skins of adult Sprague Dawley rats were obtained and treated with hypertonic sodium-SDS-trypsin to prepare the acellular dermal matrix. The tissue engineered skin was reconstructed by submerging culturing and air-liquid interface culturing in vitro. The full-thickness skin defects of 1.5 cm × 1.5 cm in size were prepared along the dorsal both sides of 36 adult inbred F344 rats, and 72 defects were repaired with tissue engineered skin in experimental group (n=24), with allogeneic acellular dermal matrix in negative control group (n=24), and with autologous full-thickness skin in positive control group (n=24). Finally the gross observation, the survival rate, wound contraction rate, and histological observation were used to evaluate the effect. Results The wound healed by first intension at 4 weeks postoperatively in the experimental group; the grafts connected with the adjacent tissue tightly and had normal appearance. At 4 weeks after operation, the survival rate of the graft was 0 in the negative control group; the survival rates were 62.5% (15/24) in the experimental group and 91.7% (22/24) in the positive control group, showing significant difference between 2 groups (χ2=5.779, P=0.016). The wound contraction rates of the experimental group and positive control group were significantly lower than that of the negative control group (P lt; 0.05), but no significant difference was found between the experimental group and positive control group (P gt; 0.05). Histological observation showed that slight inflammation reaction appeared at 1 week postoperatively in the experimental group; the regeneration of the blood vessel and the proliferation of the fibroblasts in dermis and the gradual maturation of epidermis were observed at 2 weeks, and new collagen deposition and collagen remodeling in the dermis of the graft were found at 4 weeks postoperatively. Conclusion The tissue engineered skin is able to repair full-thickness skin defect of rats effectively, it has similar effect to the autologous full-thickness skin in preventing the wound contraction and promoting the wound healing, which provides experimental evidences for the clinical application.
Objective To find out the recent progress in research of cl inical appl ication of fascia lata allograft. Methods The domestic and international articles were reviewed to summarize the princi pal properties, processing techniques, and various uses of fascia lata allograft. Results Histologically fascia lata is composed of parallel and compact bundles of collagen fibers with few cells and immunologically it is low-antigenic. After varied tissue processing and storage techniques, fascia lata, as the scaffold only with the extracellular matrix, has been used in cl inical practice and achieved good results, such as ophthalmology, urology, and orthopaedics. Conclusion Because of these unique properites in repairing defects and reconstructing functions, fascia lata allograft, as a natural biomaterial, is promising to be used in more aspects withthe development of the biomedical techniques.
Objective To research the effect of porcine acellular dermal matrix in the reconstruction of abdominal wall defects in rabbits, and to investigate the appl ication feasibil ity of xeno-transplantation of acellular dermal matrix. Methods The porcine acellular dermal matrix was prepared from a health white pig. Twenty-six Japanese white rabbits (weighing 2.2-2.3 kg, female or male) were randomly assigned to 2 groups: the control group (n=6) and the experimental group (n=20). In the control group, the full-thickness abdominal wall defect of 5.0 cm × 0.5 cm was made, and the defect wassutured directly; in the experimental group, the full-thickness abdominal wall defect of 5.0 cm × 2.5 cm was made, and the defect was repaired with porcine acellular dermal matrix patch at the same size as the defect. At 5 weeks after surgery, the incidence of hernia and the intra-abdominal adhesions were observed and the wound breaking strength was compared between the patchfascia interface and the fascia-fascia interface. The graft vascularization was evaluated through histological analysis at 6 months after surgery in the experimental group. Results No hernia occurred in all rabbits of 2 groups. At 5 weeks after surgery, heal ing was observed between patch and the muscularfascia; the vascularization was seen in the porcine acellular dermal matrix patch. There was no significant difference in the adhesion grade (Z= —0.798, P=0.425) between the experimental group (grade 2 in 1 rabbit, grade 1 in 5, and grade 0 in 12) and the control group (grade 1 in 1 and grade 0 in 5). No significant difference was found (t= —0.410, P=0.683) in the breaking strength between the patch-fascia interface in the experimental group [(13.0 ± 5.5) N] and the fascia-fascia interface in control group [(13.6 ± 4.0) N]. In the experimental group, the small vessels and the infiltration of inflammatory cells were observed in the porcine acellular dermal matrix patch after 5 weeks through histological observations. The junctions of the patch-fascia interface healed with fibrous connective tissue. At 6 months after surgery, the inflammation was subsided and the collagen fiber of the patch was reconstructed. Conclusion The porcine acellular dermal matrix patchhas good results in repairing full-thickness abdominal wall defect. The patch-fascia interface has siml iar breaking strength to the fascia-fascia interface. The collagen fibers of the patch are reconstructed.
Objective To compare the effect of the composite skin graft consisting of spl it-thickness skin grafts (STSGs) and porcine acellular dermal matrix (PADM) with STSGs only, and to histologically observe the turnover of the PADM in rats. Methods Twenty female Sprague-Dawley rats, weighing 200-225 g, were included. The size of 4.0 cm × 2.5 cm PADM was implanted into hypoderm of the left side of Sprague-Dawley rats’ back. After 10-14 days, the size of 4.0 cm × 2.5 cm full-thickness skin defects were made on the left to expose the PADM under the skin and the same size of full-thickness skin defects were made on the right of the rats’ back. The excised full-thickness skin was made to STSGs about 0.2 mm by drum dermatome. The defects were grafted with composite skin (STSGs on the PADM, experimental group) and STSGs only (control group). The survival rate, the constraction degree of grafts, and the histological change in grafts area were observed at 2, 4, 8, and 20 weeks after operation. Results At 2 weeks after STSGs (0.2 mm) placed on vascularized PADM, STSGs and PADM adhered together and the composite skin had a good survival. The control group also had a good survival. Histological observations showed that STSGs and PADM grew together, neutrophil ic granulocytes and lymphocytes infiltrated in the PADM and some macrophages around the PADM. Fibrous connective tissues were filled under the STSGs in control group. At 4-8 weeks after transplantation, the composite skin had a good survival and the composite skin was thick, soft, and elastic. STSGs survived almost totally in control group, but the grafts were thin. Histological observations showed that inflammatory reactions of PADM faded gradually in experimental group; scar tissues formed under the STSGs in control group. At 20 weeks after transplantation, composite skin was flat, thick, and elastic in experimental group, but the STSGs were thinner and less elastic in control group. Histological observations showed that histological structures of the PADM were similar to the dermal matrix of rats, and the results showed that the collagen matrix of PADM was gradually replaced by the rats’ collagen matrix. Scar tissues were filled under the STSGs in control group. Wound heal ing rates of experimental group were lower than those of control group at 4 and 8 weeks (P﹤0.05); wound contraction rates of experimental group had lower tendency than those of control group, but showing no significant differences (P gt; 0.05). Conclusion Coverage wound with composite skin which composed of STSGs and PADM could improve wound heal ing qual ity; the composite skin is thicker and better elastic than STSGs only. The collagen matrix of PADM is gradually replaced by rats’ collagen matrix.
Objective To explore the feasibil ity of using PKH26 as a cell tracer to construct tissue engineered bone. Methods BMSCs isolated from the bone marrow of 1-week-old New Zealand white rabbit were cultured. The BMSCs at passage 3 were labeled with PKH26 and were observed under fluorescence microscope. The percentage of the labeled cells wasdetected by Flow cytometer. The labeled cells were induced to differentiate into osteoblasts in vitro and the morphology of the cells after induction was observed under inverted phase contrast microscope. The osteogenic induction was evaluated by ALP staining and Alizarin red staining. The cells labeled with PKH26 were seeded on the bio-derived bone to construct tissue engineered bone in vitro. Then the compound of cells and material were observed under fluorescence microscope. The compound of labeled cells and material were implanted into the rabbit thigh muscle, and the transformation of the labeled cells was observed by fluorescence microscope 14 and 28 days later. Results Fluorescence microscope observation: the BMSCs labeled by PKH26 were spherical and presented with red and uniform-distributed fluorescence, and the contour of the cells were clearly observed when they were adherent 24 hours after culture. Flow cytometric detection revealed that the percentage of labeled cells was 97.2%. After osteogenic induction, the morphology of the cells changed from long-fusiform to polygon-shape or cube-shape, more ECM was secreted, andthe ALP and the Alizarin red staining were positive. At 48 hours after culturing the PKH26 labeled BMSCs with bio-derived bone, the fluorescence microscope observation showed that there was red fluorescence on the surface and inside of the material. At 14 days after implantation, the labeled cells with red and l ight fluorescence were evident in the implantation area; while at 28 days, the cells with red fluorescence were still evident but less in quantity and weaker in fluorescence strength. Conclusion PKH26 can be used as BMSCs label for the construction of tissue engineered bone in vitro and the short-term tracing in vivo.