Abstract:

Objective     To investigate the feasibility of matrix metalloproteinase-7 (MMP-7) reducing immunogenicity in xenogenic(porcine) acellular dermal matrix(Xeno-ADM)， which contains only dermal reticular layer， and its effect on dermal scaffold structures．  Methods      33 pieces of porcine dermal reticular layer， 0.5-0.6mm in thickness， obtained by using a mechanical method，were randomly divided into group A(normal controls), group B(decellularized by Dispase II and TritonX-100) and group C(treated with MMP-7 after decellularization)(n=11 in each group)． The samples were observed by HE staining，immunohistochemical staining(vimentin， laminin and collagen Ⅳ) and a scanning electron microscope (SEM). Quantities of cells， cell debris and hair， semiquantities of laminin and collagen Ⅳ， along with changes of the dermal scaffold structure were evaluated．  Results     HE staining， vimentin immunohistochemical staining and SEM revealed that some hair and epithelial root sheath with intact cells were observed in hair follicles ingroup B but not in group C. Some fragments which seemed to be cell nuclei or cell debris were observed in previous areas of blood vessels in group B，but they obviously decreased in group C．Semi-quantitative analysis of immunohistochemical staining showed that contents of laminin and collagen Ⅳ in group B were significantly lower than in group A(P＜0.01)，while obviously higher than in group C(P＜0.01)，in which they were almost cleared off．SEM and HE staining also showed that there was no obvious difference in the array of collagen fibers among the three groups. The interspace of collagenous fiber bundles or collagenous fibers in group B was larger than that in group A，while smaller than that in group C. In addition， no obvious fracture or degradation was observed in groups B and C．  Conclusions      After treatment with MMP-7， high immunogenic components of Xeno-ADMs produced by the porcine dermal reticular layer are significantly cleared away. Also， the dermal scaffold structure is kept, along with relatively larger interspace of collagenous fiber bundles or collagenous fibers． Therefore， MMP7 preliminarily shows good prospects in the preparation of lower immunogenic XenoADMs．

Key words: Tissue engineering derma； Matrix metalloproteinase-7； Porcine； Extracellular matrix； Immunogenicity