BACKGROUND: The pathogenesis of transition from viral myocarditis to dilated cardiomyopathy is elusive, although the incidence of dilated cardiomyopathy in human is increasing. METHODS: To clarify the role of the tissue inhibitor of matrix metaloproteinase-2 (TIMP-2) in this event, we performed immunohistochemistry, immunoblotting and immunoassay of matrix metalloproteinase-9 (MMP-9) and TIMP-2 in the serum and heart tissue of mice, which were inoculated with 4000 plaque-forming units of coxsackie B virus. RESULTS: The MMP-9 was expressed in damaged cardiomyocytes, and the TIMP-2 was expressed in mainly interstitial connective tissue between cardiac muscle bundles by immunohistochemistry. The level of serum MMP-9 was higher in the complicated than non-complicated group (p<0.001), but the level of TIMP-2 was much lower in complicated than non-complicated group (p<0.05). These findings were similar to the results of immunohistochemistry and immunoblotting in tissues. CONCLUSIONS: These results suggest that an imbalance in the level of MMP-9 and its inhibitor might activate cardiac complication in viral myocarditis.
Animals ; Cardiomyopathies ; Cardiomyopathy, Dilated ; Connective Tissue ; Heart* ; Herpesvirus 1, Cercopithecine ; Humans ; Immunoassay ; Immunoblotting ; Immunohistochemistry ; Incidence ; Matrix Metalloproteinase 2* ; Matrix Metalloproteinase 9 ; Mice* ; Myocarditis* ; Myocardium ; Myocytes, Cardiac ; Tissue Inhibitor of Metalloproteinase-2

PURPOSE: To overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model. METHODS: Four circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT). RESULTS: In both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 mm3) was larger than that of the BG group (38.71±2.24 mm3, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks. CONCLUSIONS Enhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.