Effect of the biophysical and trophic stimuli on stem cell behavior and therapeutic application in a swine model of subacute myocardial infarction

Resumen

Cell therapy constitutes a promising therapeutic approach for many pathologies including the myocardial infarction (MI) that is a leading death cause worldwide. The common therapeutic treatments for MI based on pharmacological treatment, percutaneous intervention and surgery provide symptoms attenuation and permit a good quality life, but do not support organ regeneration. Thus, the regenerative approaches including cell therapy are of great clinical interest for the treatment of this pathology. Several populations of stem cells have been studied for their regenerative potential. However, although stem cells transplantation has been shown to induce some benefits, the initially expected regenerative effect has not been fulfilled yet. A poor engraftment, survival and differentiation ability of the transplanted cells has been identified as the main caveats for their therapeutic efficacy. The soluble and biophysical cues of the surrounding environment have been described to greatly affect several aspects of stem cell behavior that span from survival to differentiation. Therefore, strategies based on the use of biomaterials have been shown to improve the efficacy of transplanted cells by providing them with the adequate stimuli. In this study, we have examined the effect of substrate biophysical properties on the differentiation of induced pluripotent stem cells (iPSCs)-derived embryoid bodies. The iPSCs, previously derived from aMHC-GFP mice fibroblasts, were cultured during 12 days on polyacrylamide(pAA)-based hydrogels of tunable stiffness (0.6, 14, and 50 kPa) or on tissue culture polystyrene plates (as control) in the presence of basal medium. All culture substrates were coated with fibronectin or collagen-I to promote cell adhesion. Cell differentiation toward the three germ layers was analyzed by real time PCR detecting an increase of tissue-specific gene markers induced by pAA matrices. Interestingly, soft matrix (0.6 kPa) coated with fibronectin favored differentiation toward cardiac and neural lineages and, in the case of neural differentiation, the effect was potentiated by the addition of specific soluble factors. The generation of mature astrocytes, neural cells, and cardiomyocytes was further proven by immunofluorescence and transmission electron microscopy. On the other hand, biomaterial devices have been promisingly used to perform the controlled delivery of growth factors, which would support tissue regeneration and stimulate stem cells behavior. In this regard, we studied the therapeutic efficacy of the growth factors IGF-1 and HGF sequentially administrated through alginate sulfate nanoparticles alone or in combination with autologous ADSCs or BOECs in a pre-clinical pig model of subacute MI. We observed that the growth factors alone or in combination with both stem cell populations induced a significant reduction of cardiac fibrosis six months upon intracoronary implantation in vivo. Moreover, a significant improvement of the cardiac function was induced by the combined administration of ADSCs or BOECS with IGF-1 and HGF six months after implantation. In summary, the results of this study show that the application of tissue engineering strategies could overcome the main limitations of cell therapy providing the adequate stimuli to promote cell survival and tissue regeneration.