Abstract Body: Background: Stroke or traumatic brain injury (TBI), due to damage to the cerebral motor cortex, often results in significant motor dysfunction and disabilities. Cell replacement therapy emerges as a prospective alternative treatment, promising to restore the impaired neural circuits and facilitate functional recovery. The current study aimed to systemically identify new factors capable of enhancing the efficacy of cell transplantation with human-induced pluripotent stem cell-derived cerebral organoids (hiPSC-COs). Earlier research demonstrated the effectiveness of delaying the transplantation procedure by 1 week and we hypothesized in this study that brain tissues 1 week after brain damage possess a more favorable environment for cell transplantation when compared to immediately after injury.

Methods and Results: Using rodent models, we made a transcriptomic comparison to differentiate gene expression between these two temporal states in order to discern novel factors that could potentiate the therapeutic impact of cell transplantation. Ultimately, 7 candidate genes coding for secreted and extracellular proteins (apolipoprotein D, cathepsin D, cathepsin S, lysozyme 2, secreted phosphoprotein 1, granulin, and secreted protein acidic and cysteine rich) were selected through the transcriptome analysis. In controlled in vitro conditions, recombinant human progranulin (rhPGRN) bolstered the survival rate of dissociated neurons sourced from hiPSC-COs by approximately 25% under oxidative stress. Further experiments revealed that this increase in viability was attributable to a reduction in apoptosis via Akt phosphorylation. In addition, rhPGRN pretreatment before in vivo transplantation experiments augmented the number of engrafted cells about 3.3 times compared to the control group and facilitated neurite elongation along the host brain’s corticospinal tracts in rodent models. Subsequent histological assessments at 3 months post-transplantation revealed an elevated presence of graft-derived subcerebral projection neurons—crucial elements for reconstituting neural circuits—in the rhPGRN-treated group.

Conclusion: Our data highlight the potential of PGRN as a neurotrophic factor suitable for incorporation into hiPSC-CO-based cell therapies for stroke or TBI.