Stem cell-mediated recovery in stroke: partnering with the immune system.

Stroke remains a leading cause of disability owing to the irreversible neuronal loss that it causes and the limited regenerative capacity of the CNS. Although reperfusion therapies such as thrombolysis and mechanical thrombectomy can restore blood flow after stroke, their stringent eligibility criteria leave many patients without treatment options. The immune response, involving complex interactions between brain-resident and peripheral immune cells, has a critical role in stroke recovery. Stem cell-based therapies, particularly those involving neural stem cells and mesenchymal stem cells, may be able to reshape the inflammatory microenvironment after stroke, mitigating secondary injury and promoting tissue repair. However, the precise mechanisms driving their effects remain incompletely understood, hindering clinical translation. In this Review, we highlight the bidirectional crosstalk between stem cells and immune cells (including microglia, T cells and peripheral immune cells) and discuss how these interactions influence neuroinflammation, neural plasticity and circuit remodelling in stroke recovery. We examine key determinants of stem cell therapy efficacy, emphasizing the role of stem cell-immune cell interactions, and discuss targeted strategies to enhance immune modulation and neuroprotection.