The role of angiogenesis in damage and recovery from ischemic stroke

Ischemic stroke is burdened with a high morbidity and mortality in our society. However, there are few effective and largely available therapies for this devastating disease. In additon to advancing acute reperfusion therapies, there is a need to develop treatments aimed to promote repair and regeneration of brain tissue damaged by ischemia (neurorecovery). Therapeutic angiogenesis and vasculogenesis represent novel approaches of regenerative medicine that may help in the cure of patients with acute ischemic stroke. Translation of our knowledge about these processes from the bench to bedside is still underway. Although angiogenesis (the sprouting of new blood vessels from pre-existing vascular structures) is likely to contribute to neurorepair, the finality of the angiogenic response in acute ischemic stroke has not been fully elucidated. The first therapeutic approach to angiogenesis after ischemic stroke would be the modulation of the endogenous angiogenic response. In this setting, early instauration of physical activity, statins, and peroxisome proliferator-activated receptor-gamma agonists may enhance angiogenesis and neuroregeneration. Gene therapy with vascular growth factors has been successfully tested in patients affected by chronic myocardial and peripheral ischemia. Regarding brain ischemia, experiments in animal models have shown that the effect of these growth factors is critically affected by the dosage, route of delivery, and time of administration in relation to stroke onset. In addition, the optimal angiogenic substance is unknown. Finally, vectors for gene transfer should be further optimized. Therapeutic vasculogenesis consists of the administration of exogenous endothelial progenitor cells in order to enhance brain repair processes. Endothelial progenitor cells may be recruited in response to cerebral ischemia and participate in reparative vasculogenesis after acute ischemic stroke. Further research is needed to clarify their role and therapeutic applicability in human brain ischemia.