Study On Matrix Metalloproteinase To Dissolve The Antigen Of Porcine Acellular Dermal Matrix

Objective The current study utilized the degradation of laminin and Col IV by MMP-7 on the basis of our previous studies, with another treatment to xenogenic(porcine) acellular dermal matrix(Xeno-ADM) by MMP-7 after decellularization, was performed to investigate the feasibility of reducing the immunogenicity in xenogenic(porcine) acellular dermal matrix(Xeno-ADM), which contains only dermal reticular layer, and the effect on its dermal scaffold structure after farther treated with MMP-7 along with its optimal concentration, and the ultimate goal was the preparation of a novel dermal scaffold with lower immunogenicity.Methods 95 pieces of porcine dermal reticular layer,0.5-0.6mm thick, obtained by using a mechanical method, were randomly divided into group A(normal control, n=11), group B(with decellularization by DispaseⅡand TritonX-100 and then treated by PBS under the same conditions with the treatment of MMP-7,n=21) and group C1, C2, C3(respectively with another treatment by 0.1 U/ml,0.5U/ml,1U/ml MMP-7 after decellularization, n=21). The samples were made the observation of HE staining, immunohistochemical staining(Vimentin, LN and Col IV) and scanning electron microscope (SEM), to evaluate the quantity of cells, cell debris and hair, the semiquantity of laminin and Collagen IV, along with the effect on the dermal scaffold structure.Results (1)HE staining, Vimentin immunohistochemical staining and SEM revealed that some hair and epithelial root sheath with intact cells were observed in hair follicle of group B and comparatively few in group C1, but not in group C2, C3; and some fragments which seemed to be cell nucleus or cell debris were observed in previous areas of blood vessels in group B and group C1, but they obviously decreased in group C2, C3. (2)Semiquantitative analysis of Laminin, CollagenⅣimmunohistochemical staining showed that the content of these two components in group B was significantly lower than that of group A(P<0.01), but obviously higher than that of group C1, C2, C3(P< 0.01), and they were almost cleared off in group C2, C3. (3)SEM and HE staining also showed that there were no obvious differences in the array of collagen fibers among the five groups; and the interspace of collagenous fibers or collagen fibril in group B was larger than that of group A, but smaller than that of group C1, whose is smaller than that of C2 and C3; in addition, no obvious fracture and degradation were observed in group B and C.Conclusions (1) Experimental result shows that after treated with MMP-7, high immunogenic components of the Xeno-ADMs produced by porcine dermal reticular layer are significantly cleared away, meanwhile, the dermal scaffold structure is kept along with larger interspace of collagenous fibers or collagen fibril to some degree. Therefore, MMP-7 used in the preparation of lower immunogenic Xeno-ADMs Preliminarily shows a good study and application prospects. (2) This study Compared the effection of three different concentration of MMP-7, and after treated by 0.5U/ml MMP-7, no hair and epithelial root sheath with intact cells or fragments which seemed to be cell nucleus or cell debris are observed, as well as LN and Col IV immunohistochemical staining is weak. So the optimal concentration of MMP-7 used for treating Xeno-ADM is 0.5U/ml.