ObjectiveTo investigate the histological changes and vascularization of the porcine acellular dermal matrix (P-ADM) processed with matrix metalloproteinase 7 (MMP-7) (P-ADM-pm) after implanted into rats. MethodsSixty-two pieces of porcine reticular layer dermis which were from the pig abdominal skin and obtained by using a mechanical method, were randomly divided into group A (n=31) and group B (n=31). The porcine reticular layer dermis in 2 groups were treated with decellularization (P-ADM), then the P-ADM in group B were treated with processing by MMP-7 (P-ADM-pm). Thirty adult male Wistar rats were selected. P-ADM (group A) and P-ADM-pm (group B) were subcutaneously transplanted into the left and right fascia lacuna, respectively. The implants were harvested from 6 rats at 3, 7, 14, 21, and 28 days after implantation, respectively. Gross, histochemical, and immunohistochemical observations, and scanning electron microscopy (SEM) examination were performed to observe host cells, microvessels infiltration and histological changes in the implants. ResultsNo rat died in the experiment, incision healed well and no obvious inflammatory reaction was seen in all rats. Gross observation suggested that the implants of 2 groups were encapsulated by a thin layer of connective tissue at 7 days after implantation. With the time of implantation, the microvessels increased and coarsened, and the changes of group B were more obvious than those of group A. At 21 days, the microvessels of 2 groups decreased, and the implants of group B showed complete vascularization. The histochemical and immunohistochemical observations showed that group A had more severe inflammatory response than group B. Fibroblasts and microvessels in group B appeared in the superficial zone of implant at 3 and 7 days after implantation and they could be observed in the center zone of implant at 14 and 21 days. However, fibroblasts and microvessels in group A appeared in the superficial zone of implant at 3 and 14 days and they could not be observed in the center zone of implant at 28 days. Fibroblasts and microvessels of group B were significantly more than those of group A (P < 0.05). SEM examination showed that more fibroblasts and new collagen fibrils were observed in group B at 14 days. ConclusionThe host response to P-ADM-pm is similar to normal wound healing, and P-ADM-pm as implantable scaffold material plays a good template conduction role.