Amnion epithelial cells - a novel therapy for ischemic stroke?

Abstract

Stroke is a leading cause of death and disability and new therapies are desperately needed. Given the complex nature of ischemic brain injury, it has been postulated that cell-based therapies may be useful. However, cell resources, invasive extraction procedures, immunological rejection, tumorigenesis and ethical challenges make it unlikely that many stem cell types could serve as a practical source for therapy. By contrast, these issues do not pertain to human amnion epithelial cells (hAECs), which are placenta-derived stem cells. We recently assessed the effects of systemically delivered hAECs on stroke outcome using four animal models of stroke. We demonstrated that when injected intravenously after ischemia onset, hAECs migrate preferentially to the spleen and injured brain to limit apoptosis and inflammation, and attenuate early brain infiltration of immune cells, progression of infarction and systemic immunosuppression and to ultimately ameliorate functional deficits. When administration of hAECs is delayed by 1-3 days post-stroke, long-term functional recovery can still be enhanced in young and aged mice of either sex. Moreover, our proof-of-principle findings suggest that hAECs are effective at limiting post-stroke infarct development in non-human primates. Overall, the results suggest that hAECs could be a viable clinical stroke therapy.

Keywords: brain repair; cerebral infarction; human amnion epithelial cells; immunosuppression; inflammation; ischemic stroke; mouse; non-human primate; stem cells.

Figure 1

A schematic of the likely mechanisms by which human amnion epithelial cells (hAECs) improve outcome after stroke. When administered acutely after ischemia onset (1.5 hours post-stroke), hAECs preferentially migrate to the spleen and injured brain to limit apoptosis and inflammation, and attenuate early brain infiltration of immune cells, progression of infarction and systemic immunosuppression to ultimately ameliorate functional deficits. When administration of hAECs is delayed by 1–3 days post-stroke, long-term functional recovery can still be enhanced, likely by increasing numbers of microtubule-associated protein 2 (MAP-2) positive neurons as well as altering the structure of the glial scar and numbers of immune cells in lymphoid tissue. Diagram adapted from Evans et al., 2018.