Stem Cells from Adipose Tissue
Executive summary: Stroke
Stroke is the most common cause of adult acquired disability in the developed and developing world. With an aging population, the incidence and prevalence of stroke are predicted to rise. Stroke is an acuteonset clinical syndrome that develops following a vascular insult to the brain. Brain ischemia resulting from thromboembolism or less frequently, in situ thrombosis, constitutes 80%−85%, and haemorrhage resulting from hypertension or vessel wall pathology constitutes 15%−20% of all strokes. Following vascular occlusion, a complex chain of events occurs at a molecular level, leading to irreversible tissue injury, including failure of energy synthesis, loss of transmembrane ionic gradients dependent on active transport, cell depolarization, and excitotoxicity due to the excess release of excitatory neurotransmitters. In the region with severely reduced blood flow (the ischemic core), these processes result in rapid cell necrosis affecting all the cellular elements (neurons, glia, and blood vessels). A region around the core (the ischemic penumbra) transiently maintains a collateral blood supply sufficient for cell viability. Restoring perfusion can salvage penumbral tissue, and timely recanalization is the most robust predictor of good clinical prognosis following ischemic stroke. Cell therapies probably act on multiple mechanisms in ischemic stroke, depending upon the timing and mode of administration; however, unlike neuroprotectant drugs, cell therapies have the advantage that they may be able to respond dynamically to an environment that varies both temporally and spatially after ischemia, rather than targeting a single pathway or mechanism of action.