Prolonged human neural stem cell maturation supports recovery in injured rodent CNS
Paul Lu, … , Eileen Staufenberg, Mark H. Tuszynski
Paul Lu, … , Eileen Staufenberg, Mark H. Tuszynski
Published September 1, 2017; First published August 21, 2017
Citation Information: J Clin Invest. 2017;127(9):3287-3299. https://doi.org/10.1172/JCI92955.
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Categories: Research Article Neuroscience

Prolonged human neural stem cell maturation supports recovery in injured rodent CNS

Abstract

Neural stem cells (NSCs) differentiate into both neurons and glia, and strategies using human NSCs have the potential to restore function following spinal cord injury (SCI). However, the time period of maturation for human NSCs in adult injured CNS is not well defined, posing fundamental questions about the design and implementation of NSC-based therapies. This work assessed human H9 NSCs that were implanted into sites of SCI in immunodeficient rats over a period of 1.5 years. Notably, grafts showed evidence of continued maturation over the entire assessment period. Markers of neuronal maturity were first expressed 3 months after grafting. However, neurogenesis, neuronal pruning, and neuronal enlargement continued over the next year, while total graft size remained stable over time. Axons emerged early from grafts in very high numbers, and half of these projections persisted by 1.5 years. Mature astrocyte markers first appeared after 6 months, while more mature oligodendrocyte markers were not present until 1 year after grafting. Astrocytes slowly migrated from grafts. Notably, functional recovery began more than 1 year after grafting. Thus, human NSCs retain an intrinsic human rate of maturation, despite implantation into the injured rodent spinal cord, yet they support delayed functional recovery, a finding of great importance in planning human clinical trials.

Authors

Paul Lu, Steven Ceto, Yaozhi Wang, Lori Graham, Di Wu, Hiromi Kumamaru, Eileen Staufenberg, Mark H. Tuszynski

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Figure 1

H9-NSC graft morphology and Ki67 immunolabeling.

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H9-NSC graft morphology and Ki67 immunolabeling. (A–E) Graft size was st...
(A–E) Graft size was stable over time in the C5 hemisection lesion site, and grafts were well integrated with the host. GFP and GFAP double-labeling (horizontal sections). (F) Grafts nonsignificantly expanded from 1 to 3 months after grafting (P = 0.6, by ANOVA) and were stable in size thereafter. Data represent the mean ± SEM. (G) The total number of grafted human cells (detected by hNu, a human-specific cell marker) was significantly reduced at 3 and 6 months, but recovered by 12 and 18 months. P < 0.05, by ANOVA and **P < 0.001 and *P < 0.05, by Fisher’s exact post-hoc test. Data represent the mean ± SEM. (H–J) Cell proliferation was significantly reduced after 3 months. hNu indicates the human-specific nucleus marker; Ki67 labels proliferating cells. P < 0.0001, by ANOVA and ***P < 0.001 and **P < 0.01, by Fisher’s exact post-hoc test comparing results at 1 and 3 months with results at 6, 12, and 18 months, respectively. Data represent the mean ± SEM. For F, G, and J: 1 month, n = 3; 3 months, n = 3; 6 months, n = 5; 12 months, n = 3; and 18 months, n = 4. Scale bars: 550 μm (A–E); 7 μm (H and I).