Intracerebral transplantation of HLA‐homozygous human iPSC‐derived neural precursors ameliorates the behavioural and pathological deficits in a rodent model of ischaemic stroke

Objectives Human‐induced pluripotent stem cells (hiPSCs) are a promising cell source for treating ischaemic stroke. Although autologous hiPSCs provide the advantage of avoiding immune rejection, their practical limitations, such as substantial amount of time and costs to generate individual iPSC lines, have hampered their widespread application in clinical settings. In this study, we investigated the therapeutic potential of neural precursor cells derived from human HLA‐homozygous induced pluripotent stem cells (hiPSC‐NPCs) following intracerebral transplantation into a rodent model of middle cerebral artery occlusion (MCAo). Materials and Methods We differentiated a GMP‐grade HLA‐homozygous hiPSC line (CMC‐hiPSC‐004) into neural precursor cells for transplantation into rats at the subacute stage of ischaemic stroke (ie at 7 days after the induction of MCAo). To investigate functional recovery, the transplanted animals were subjected to five behavioural tests, namely the rotarod, stepping, mNSS, staircase and apomorphine‐induced rotation tests, for up to 12 weeks, followed by histological analyses. Results We observed that the hiPSC‐NPC transplantation produced significant behavioural improvements. At 12 weeks post‐transplantation, a high proportion of transplanted cells survived and had differentiated into MAP2+ mature neurons, GABAergic neurons and DARPP32+ medium spiny neurons. The transplanted cells formed neuronal connections with striatal neurons in the host brain. In addition, hiPSC‐NPC transplantation gave rise to enhanced endogenous repair processes, including decreases of post‐stroke neuroinflammation and glial scar formation and an increase of proliferating endogenous neural stem cells in the subventricular zone as well as the perilesional capillary networks. Conclusions These results strongly suggest that HLA‐homozygous hiPSC‐NPCs may be useful for treating ischaemic stroke patients. We transplanted neural precursor cells derived from HLA homozygous hiPSC into the subacute‐stage ischemic stroke rats and observed significant behavioral improvements in the rotarod, stepping, mNSS, staircase and apomorphine‐induced rotation tests. At 12 weeks post‐transplantation, a high proportion of transplanted cells survived and were differentiated into MAP2+ mature neurons, GABAergic neurons and DARPP32+ medium spiny neurons. Transplanted cells formed a neuronal connection with striatal neurons in the host brain. They also gave rise to enhanced endogenous rep