Células madre adultas y factores pro-arteriogénicos para el tratamiento de la isquemia periférica

Résumé

In ischemic diseases, like peripheral arterial disease (PAD), there is an inadequate blood supply that can cause tissue death. Therapeutic revascularization techniques are not applicable or not effective in all patients. Alternative therapies have been proposed, mainly focused on vascular regeneration by cell therapy or gene/protein delivery. Our aim was to identify adult stem cells and cytokines that contribute to revascularization and muscular regeneration in PAD. We, first, characterize the muscular damage caused by severe hind limb ischemia in a nude mouse model by ligation and section of iliac artery. We have demonstrated an acute muscular damage with breakage of myofibers and loss of contractile and structural proteins. We have compared on this animal model the therapeutic potential of two populations of human adult stem cells: umbilical cord blood-derived AC133+ cells and bone marrow-derived MAPC. MAPC had a more durable effect (30 days) on limb reperfusion than AC133+ cells. Both cell types differentiated in-vivo into endothelial cells but only MAPC were able to differentiate to smooth muscle cells. Both cell types stimulated angiogenesis and arteriogenesis, however, AC133+ cells mainly affected capillary growth, while MAPC improved specifically arterial growth. MAPC, unlike AC133+ cells, improved muscle viability and regeneration. We have demonstrated that MAPC secrete factors which stimulate in-vitro proliferation and survival of vascular and muscular cells. We, finally, evaluated the therapeutic potential of local and continuous administration of arteriogenic cytokines (VEGF, Shh and Dll4) in the ischemia model, compared with the angiogenic factor VEGF alone. The combination of the cytokines (named ¿arterial media¿) had an early (7 days) positive effect on limb reperfusion. VEGF and arterial media similarly improved angiogenesis, but arterial media had a robust and prolonged effect on arterial growth. Administration of VEGF or arterial media did not inhibited remodeling processes on skeletal muscle. Both treatments, instead, had an early (7 days) effect on skeletal muscle regeneration and arterial media showed a trend towards long-term protective effect on muscle (30 days). Our data point to new therapeutic strategies based on cell therapy or protein delivery for ischemic disease by inducing specifically arterial growth on the ischemic tissue.