Polyurethane scaffolds seeded with genetically engineered skeletal myoblasts: a promising tool to regenerate myocardial function.

In animal models, intramyocardial injection of primary skeletal myoblasts is supposed to promote tissue regeneration and to improve cardiac function after myocardial infarction. The usage of genetically engineered myoblasts overexpressing the paracrine factors involved in tissue repair is believed to enhance these effects. However, cell therapy via injection is always accompanied by a high death rate of the injected cells. Here, we describe the construction of a growth factor-producing myoblast-seeded scaffold to overcome this limitation. Skeletal myoblasts were isolated and expanded from newborn Lewis rats. Cells were seeded on polyurethane (PU) scaffolds (Artelon) and transfected with DNA of VEGF-A, HGF, SDF-1, or Akt1 using the lipid-based Metafectene Pro method. Overexpression was verified by ELISA, RT-PCR (VEGF-A, HGF, and SDF-1) and Western blot analysis (Akt1). The seeded scaffolds were transplanted onto damaged myocardium of Lewis rats 2 weeks after myocardial infarction. Six weeks later, their therapeutic potential in vivo was analyzed by measurement of infarction size and capillary density. Primary rat skeletal myoblasts seeded on PU scaffolds were efficiently transfected, achieving transfection rates of 20%. In vitro, we noted a significant increase in expression of VEGF-A, HGF, SDF-1, and Akt1 after transfection. In vivo, transplantation of growth factor-producing myoblast-seeded scaffolds resulted in enhanced angiogenesis (VEGF-A, HGF, and Akt1) or a reduced infarction zone (SDF-1 and Akt1) in the ischemically damaged myocardium. In summary, we constructed a growth factor-producing myoblast-seeded scaffold which combines the beneficial potential of stem cell transplantation with the promising effects of gene-therapeutic approaches. Because this matrix also allows us to circumvent previous cell application drawbacks, it may represent a promising tool for tissue regeneration and the re-establishment of cardiac function after myocardial infarction.