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 evaluate the cytotoxicity of microdosis peracetic acid (PAA) so as to provide the evidence for making residual l imit of PAA steril ization. Methods Mouse fibroblasts (L929 cell l ine) cultured in vitro were observed to evaluate the influence of microdosis PAA including 1 × 10-6, 2 × 10-6, 3 × 10-6, 4 × 10-6, 5 × 10-6, and 10 × 10-6 (V/V). Theproliferation of cells was determined by MTT assay at 2, 4, and 7 days of culture. The growth curve and the relative growth rate (RGR) were obtained. The cytotoxicity of PAA at different concentrations was evaluated according to RGR. Results At 2, 4, and 7 days after culture, fibroblasts of 1 × 10-6 group grew with normal morphology analogous to control group, while the cell growth of other groups were poor. With the increase of PAA concentration, the absorbance (A) values decreased, which suggested that there was a significant negative correlation between cell prol iferation and PAA concentration. And the correlation coefficient was — 1.000 at 2 and 4 days, — 0.964 at 7 days. There was no significant difference in A value between 1 × 10-6 group and the control group (P gt; 0.05), while there were significant differences in A value between the control group and other concentration groups (P lt; 0.05). The growth curve of 1 × 10-6 group was similar to that of the control group, both had obvious phase of exponential growth. The growth curves of other groups had no obvious phase of exponential growth. The cytotoxicity of 1 × 10-6 group was classified as level 1, 2 × 10-6 group as level 2, 3 × 10-6 group as level 3, 4 × 10-6 group as level 3-4, 5 × 10-6 group and 10 × 10-6 group as level 4. Conclusion PAA of 1 × 10-6 had no obvious cytotoxicity. The residual l imit of PAA less than 1 × 10-6 was recommended.