Safety evaluation of intra-arterial cell delivery in stroke patients—a framework for future trials

Effective treatments are not yet available for the majority of stroke patients despite the significant advances in acute stroke management and care evident since the advent of therapeutic recanalization in 2015. Unfortunately, even patients who are eligible for recanalization treatment often suffer from residual functional deficits. Hence, there is an unmet demand for additional stroke therapies promoting functional recovery, not only those that can be considered as complementary approaches to recanalization but also for treatments that can be provided beyond its narrow time window. Cell therapies are an emerging paradigm in translational neuroscience and have been widely investigated in experimental stroke models (1). Preclinical evidence collected over the past two decades has revealed that administration of cells can exert robust effects in improving functional outcome when delivered in subacute (2,3) and even in chronic stroke stages (4). These promising findings have promoted small, early phase clinical studies intended to assess the feasibility, safety and efficacy of cell therapy approaches (5).