Stand alone or join forces? Stem cell therapy for stroke.

INTRODUCTION: Stroke is a major cause of mortality and disability with a narrow therapeutic window. Stem cell therapy may enhance the stroke recovery. AREAS COVERE: Regenerative medicine via stem cells stands as a novel therapy for stroke. In particular, bone marrow-derived mesenchymal stem cells (MSCs) have neuroprotective and anti-inflammatory properties that improve brain function after stroke. Here, we discuss the safety, efficacy, and mechanism of action underlying the therapeutic effects of bone marrow-derived MSCs. We also examine the discrepant transplant protocols between preclinical studies and clinical trials. Laboratory studies show the safety and efficacy of bone marrow-derived MSCs in stroke models. However, while safe, MSCs remain to be fully evaluated as effective in clinical trials. Furthermore, recognizing the multiple cell death processes associated with stroke, we next discuss the potential therapeutic benefits of a combination therapy. With preliminary results and on-going clinical trials, a careful assessment of dosing, timing, and delivery route regimens will further direct the future of stem cell therapy for neurological disorders, including stroke. EXPERT OPINION: Bone marrow-derived MSCs appear to be the optimal stem cell source for stroke therapy. Optimizing dosing, timing, and delivery route should guide the clinical application of bone marrow-derived MSCs.