Lei H, Leong D, Smith LR, Barton ER. Matrix metalloproteinase 13 is a new contributor to skeletal muscle regeneration and critical for myoblast migration. Am J Physiol Cell Physiol 305: C529-C538, 2013. First published June 12, 2013 doi:10.1152/ajpcell.00051.2013.-Efficient skeletal muscle repair and regeneration require coordinated remodeling of the extracellular matrix (ECM). Previous reports have indicated that matrix metalloproteinases (MMPs) play the pivotal role in ECM remodeling during muscle regeneration. The goal of the current study was to determine if the interstitial collagenase MMP-13 was involved in the muscle repair process. Using intramuscular cardiotoxin injections to induce acute muscle injury, we found that MMP-13 expression and activity transiently increased during the regeneration process. In addition, in muscles from mdx mice, which exhibit chronic injury, MMP-13 expression and protein levels were elevated. In differentiating C2C12 cells, a murine myoblast cell line, Mmp13 expression was most pronounced after myoblast fusion and during myotube formation. Using pharmacological inhibition of MMP-13 to test whether MMP-13 activity is necessary for the proliferation, differentiation, migration, and fusion of C2C12 cells, we found a dramatic blockade of myoblast migration, as well as a delay in differentiation. In contrast, C2C12 cells with stable overexpression of MMP-13 showed enhanced migration, without affecting myoblast maturation. Taken together, these results support a primary role for MMP-13 in myoblast migration that leads to secondary effects on differentiation.collagenase; matrix metalloproteinase; muscle repair; myoblast maturation

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This systematic review aimed to appraise the quality of life of patients with restored endodontically treated teeth. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were employed. The specific PEO question was as follows: population: patients who were healthy individuals ≥18 years old and required endodontic treatment; exposure: endodontic treatment with a coronal restoration with at least 6 months in occlusal function; and outcome: quality of life of patients. Databases were searched in conjunction with hand searching of reference lists of endodontic textbooks, endodontic-related journals, and relevant articles from electronic searching. Six articles met the inclusion criteria. Most studies concluded that non-surgical root canal therapy improved patients' quality of life. The effect of operator type yielded conflicting results. Only one paper compared endodontic treatment with implant placement, and it showed similar patient-centric outcome with a high level of patient satisfaction. Current research is still limited, and further studies are warranted.

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ObjectivesThe biocompatibility of two experimental scaffolds for potential use in revascularization or pulp regeneration was evaluated.Materials and MethodsOne resilient lyophilized collagen scaffold (COLL), releasing metronidazole and clindamycin, was compared to an experimental injectable poly(lactic-co-glycolic) acid scaffold (PLGA), releasing clindamycin. Human dental pulp stem cells (hDPSCs) were seeded at densities of 1.0 × 104, 2.5 × 104, and 5.0 × 104. The cells were investigated by light microscopy (cell morphology), MTT assay (cell proliferation) and a cytokine (IL-8) ELISA test (biocompatibility).ResultsUnder microscope, the morphology of cells coincubated for 7 days with the scaffolds appeared healthy with COLL. Cells in contact with PLGA showed signs of degeneration and apoptosis. MTT assay showed that at 5.0 × 104 hDPSCs, COLL demonstrated significantly higher cell proliferation rates than cells in media only (control, p < 0.01) or cells co-incubated with PLGA (p < 0.01). In ELISA test, no significant differences were observed between cells with media only and COLL at 1, 3, and 6 days. Cells incubated with PLGA expressed significantly higher IL-8 than the control at all time points (p < 0.01) and compared to COLL after 1 and 3 days (p < 0.01).ConclusionsThe COLL showed superior biocompatibility and thus may be suitable for endodontic regeneration purposes.