Future of Animal Modeling for Poststroke Tissue Repair

Numerous preclinical animal studies have shown beneficial effects of cell therapies after stroke, including reduction of functional deficits and lesion size. Early stage clinical studies currently aim to confirm this therapeutic potential. Despite the progress in translating cell therapy for stroke, true cell replacement and stem cell-based tissue regrowth have not been achieved yet. Multimodal regeneration improving effects, such as immunomodulation or paracrine growth factor support, are considered the primary mechanisms of action in cell therapies.1 This is not surprising for systemically administered adult progenitor or mixed populations, which typically do not enter brain tissue. However, even brain tissue-derived cells that, in principle, have the ability to give rise to neurons and glia are thought to exert their therapeutic benefits mainly via multimodal regeneration improving effects.2 Current clinical trials are designed to reflect this supportive role of cell therapy rather than tissue reconstruction.3