Stem cell therapies for ischemic stroke: current animal models, clinical trials and biomaterials

Ischemic stroke is one of the most common causes of death. A brain that has suffered a stroke is significantly damaged due to the transient interruption of blood supply. Stroke survivors suffer from stroke-induced cognitive, motor and psychiatric problems that require increased use of the health care system, which results in a very poor quality of life and a heavy emotional and financial burden for patients and their families. Although rehabilitation can ameliorate some behavioral abnormalities, it does not significantly improve stroke symptoms. Neuroregeneration may be the principle process for replenishing of lost brain functions. Stem cell therapy is a novel approach to restore neurological function following ischemic stroke. Our goal in this review is to first briefly introduce the pathophysiology of stroke then document the progress of stem cell research, including clinical trials, towards the treatment of ischemic stroke. We highlight the promising applications of biomaterials to enhance the therapeutic effect of stem cell therapy in stroke treatment. As biomaterials provide efficient scaffolds for the growth and differentiation of stem cells, they may guarantee the quality and yield of stem cells for grafting. Furthermore, biomaterials also provide a convenient method for delivering the stem cells to be transplanted. This review provides direction for future research to combine tissue engineering approaches with stem cell therapy for the treatment of stroke.