Monoclonal antibody‐mediated immunosuppression enables long‐term survival of transplanted human neural stem cells in mouse brain

Abstract

Background As the field of stem cell therapy advances, it is important to develop reliable methods to overcome host immune responses in animal models. This ensures survival of transplanted human stem cell grafts and enables predictive efficacy testing. Immunosuppressive drugs derived from clinical protocols are frequently used but are often inconsistent and associated with toxic side effects. Here, using a molecular imaging approach, we show that immunosuppression targeting costimulatory molecules CD4 and CD40L enables robust survival of human xenografts in mouse brain, as compared to conventional tacrolimus and mycophenolate mofetil. Methods Human neural stem cells were modified to express green fluorescent protein and firefly luciferase. Cells were implanted in the fimbria fornix of the hippocampus and viability assessed by non‐invasive bioluminescent imaging. Cell survival was assessed using traditional pharmacologic immunosuppression as compared to monoclonal antibodies directed against CD4 and CD40L. This paradigm was also implemented in a transgenic Alzheimer's disease mouse model. Results Graft rejection occurs within 7 days in non‐immunosuppressed mice and within 14 days in mice on a traditional regimen. The addition of dual monoclonal antibody immunosuppression extends graft survival past 7 weeks (p < .001) on initial studies. We confirm dual monoclonal antibody treatment is superior to either antibody alone (p < .001). Finally, we demonstrate robust xenograft survival at multiple cell doses up to 6 months in both C57BL/6J mice and a transgenic Alzheimer's disease model (p < .001). The dual monoclonal antibody protocol demonstrated no significant adverse effects, as determined by complete blood counts and toxicity screen. Conclusions This study demonstrates an effective immunosuppression protocol for preclinical testing of stem cell therapies. A transition towards antibody‐based strategies may be advantageous by enabling stem cell survival in preclinical studies that could inform future clinical trials.

Human neural stem cells restore spatial memory in a transgenic Alzheimer’s disease mouse model by an immunomodulating mechanism

“…Therefore, we opted to perform our spatial transcriptomics analysis using the more effective IGF-I-expressing hNSC line with a view towards supporting future translational clinical trials implementing this cell line. We also demonstrated that injected hNSCs chiefly reside within the fimbria fornix and corpus callosum, but that a fraction migrates throughout the hippocampus, cortex, and other areas of the brain ( Mcginley et al, 2022 ).…”

“…Representative fluorescence imaging (right panel; scale bar = 2 mm) shows GFP-labeled hNSCs disperse throughout the cortex following injection. Adapted from ( McGinley et al, 2022 ). (B) Latency to the hidden platform with training over days 1 to 9 and a visible (vis) positive control on day 10 in the Morris Water Maze test for WT (black), untreated 5XFAD (grey), vehicle injected 5XFAD (blue), and hNSC injected 5XFAD (red) mice; n = 7–10, * p < 0.05, by two-way ANOVA.…”

“…Injections (20 mg/kg intraperitoneal for each antibody) began starting 1 day prior to the surgical procedure and occurred daily for 4 days, then weekly thereafter for the duration of the experiment. hNSC were transduced to express GFP and firefly luciferase ( Mcginley et al, 2022 ), and transplants were performed in 5XFAD mice at 6 weeks of age (3 bilateral injections of hNSCs at 50,000 cells/μL, 2 μL per injection, for a total of 600,000 cells per animal).…”

“…We previously showed that a human neural stem cell line (hNSC) improves spatial memory in an AD mouse model ( Mcginley et al, 2018 ). These hNSCs express insulin-like growth factor-I (IGF-I), survive in the long-term ( Mcginley et al, 2022 ), and exert immunomodulatory ( Mcginley et al, 2018 ) and neuroprotective ( Mcginley et al, 2016 ) effects in the brain of AD mice following transplantation into the fimbria fornix of the hippocampus. In the current study, we performed spatial transcriptomics of brain tissue following hNSC transplantation into transgenic 5XFAD AD mice.…”

The past and present of therapeutic strategy for Alzheimer’s diseases: potential for stem cell therapy

“…Transplanted NSCs have been reported to have long-term survival in vivo with the maintenance of multilineage differentiation, such as integration, synapse formation, and functional activity, and without tumorigenic growth in AD model mice [123]. The long-term survival of transplanted neural cells into the brain has been prolonged by immunosuppression of xenograft rejection in AD model mice [124]. Currently, many stem cell therapies have progressed well in clinical trials [33,125] by accumulating findings through basic research, including animal experiments.…”