Characterization of a Thermostable and Surfactant-Tolerant Chondroitinase B from a Marine Bacterium Microbulbifer sp. ALW1.

Chondroitinase plays an important role in structural and functional studies of chondroitin sulfate (CS). In this study, a new member of chondroitinase B of PL6 family, namely ChSase B6, was cloned from marine bacterium Microbulbifer sp. ALW1 and subjected to enzymatic and structural characterization. The recombinant ChSase B6 showed optimum activity at 40 °C and pH 8.0, with enzyme kinetic parameters of Km and Vmax against chondroitin sulfate B (CSB) to be 7.85 µg/mL and 1.21 U/mg, respectively. ChSase B6 demonstrated thermostability under 60 °C for 2 h with about 50% residual activity and good pH stability under 4.0-10.0 for 1 h with above 60% residual activity. In addition, ChSase B6 displayed excellent stability against the surfactants including Tween-20, Tween-80, Trion X-100, and CTAB. The degradation products of ChSase B6-treated CSB exhibited improved antioxidant ability as a hydroxyl radical scavenger. Structural analysis and site-directed mutagenesis suggested that the conserved residues Lys248 and Arg269 were important for the activity of ChSase B6. Characterization, structure, and molecular dynamics simulation of ChSase B6 provided a guide for further tailoring for its industrial application for chondroitin sulfate bioresource development.

Enhancing efficacy of stem cell transplantation to the heart with a PEGylated fibrin biomatrix.

Bone marrow-derived mononuclear cell (BMNC) transplantation provides the possibility of rescue or regeneration of myocardium lost during acute myocardial infarction (AMI). The extensive death of transplanted cells and the lack of sustained engraftment may limit its application. We investigated whether delivery of BMNCs by an injectable PEGylated fibrin biomatrix that covalently binds hepatocyte growth factor (HGF) would enhance the rate of cell engraftment and improve cardiac function. Balb/C female mice with AMI secondary to left anterior descending coronary ligation were randomly assigned to one of six groups: the Saline control group (n = 8) received a myocardial injection of saline (50 microL); the Cell group (n = 10) received a myocardial injection in the peri-infarct and infarct zones consisting of 500,000 murine BMNCs suspended in 50 microL saline; and the Biomatrix + HGF (n = 9) and Biomatrix + HGF + Cell (n = 9) group hearts received the HGF-loaded injectable biomatrix (identical volume) with or without entrapped BMNCs. Control groups consisting of the biomatrix alone (n = 9) and Biomatrix + Cells (n = 9) without HGF were also included for comparison. The left ventricular (LV) function was measured by echocardiography at days 14 and 28 post-MI. All animals were euthanized 4 weeks after AMI and transplantation for evaluation of angiogenesis, apoptosis, and fibrosis by immunohistochemistry. Cell prevalence rate at 4 weeks increased 15-fold in hearts receiving the Biomatrix + HGF + Cell delivery (p < 0.01), which was accompanied by the lowest levels of apoptosis and the highest LV function recovery among the treated groups.