Hyaluronan (HA) has been shown to play an important role during early heart development and promote angiogenesis under various physiological and pathological conditions. In recent years, stem cell therapy, which may reduce cardiomyocyte apoptosis, increase neovascularization, and prevent cardiac fibrosis, has emerged as a promising approach to treat myocardial infarction (MI). However, effective delivery of stem cells for cardiac therapy remains a major challenge. In this study, we tested whether transplanting a combination of HA and allogeneic bone marrow mononuclear cells (MNCs) promotes cell therapy efficacy and thus improves cardiac performance after MI in rats. We showed that HA provided a favorable microenvironment for cell adhesion, proliferation, and vascular differentiation in MNC culture. Following MI in rats, compared with the injection of HA alone or MNC alone, injection of both HA and MNCs significantly reduced inflammatory cell infiltration, cardiomyocyte apoptosis, and infarct size and also improved cell retention, angiogenesis, and arteriogenesis, and thus the overall cardiac performance. Ultimately, HA/MNC treatment improved vasculature engraftment of transplanted cells in the infarcted region. Together, our results indicate that combining the biocompatible material HA with bone marrow stem cells exerts a therapeutic effect on heart repair and may further provide potential treatment for ischemic diseases.

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The long-standing paradigm for pathogenesis of bacteremia is that, in most cases, a single organism passes through a bottleneck and establishes itself in the bloodstream (single-organism hypothesis). In keeping with this paradigm, standard practice in processing positive microbiologic cultures is to test single bacterial strains from morphologically distinct colonies.