Modeling Charcot Marie Tooth 1A with Human Pluripotent Stem Cells
Embargo until
2020-05-01
Date
2017-03-24
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Publisher
Johns Hopkins University
Abstract
We have developed a defined protocol for the direct derivation and prospective isolation of Schwann cells from human embryonic and induced pluripotent stem cells. Potential uses of these cells include disease modeling, drug screening, and transplantation therapy, making it an exciting platform for translational research and personalized medicine. This method was applied to model CMT1A, a genetic peripheral neuropathy characterized by a 1.4 MB duplication on chromosome 14. Results from profiling CMT1A hiPSC-Schwann cells were validated using CMT1A PGD-hESC-Schwann cells and CMT1A iNC-Schwann cells. All three models displayed increased expression of the Peripheral Myelin Protein (PMP22) transcript, the gene believed to cause CMT1A. Two of the three models demonstrated upregulated expression of the heparan sulfate biosynthesis gene, HS3ST3b1, which is also located in the 1.4 MB CMT1A duplicated region, plays a rate limiting role in heparan sulfate fine structure biosynthesis, and whose specific role in Schwann cells is yet to be determined. Most interestingly, two pro-inflammatory cytokines, CXCL1 and MCP-1 proteins, were ultimately commonly overexpressed in all three models, and their overexpression was also confirmed in nerve biopsies from two CMT1A patients. It was also found that CMT1A Schwann cells of all three models could more readily recruit human THP-1 monocytes, and that this recruitment occurred in an MCP-1 dependent manner. Finally, through treatment with three small molecules previously identified to decrease PMP22 gene expression, we found a compound (bortezomib) that decreased both PMP22 gene and MCP-1 protein expression in Schwann cells from hiPSCs from one patient, in an example of how hiPSC-derived Schwann cells may be used for patient-specific therapeutic studies going forward.
These results imply pro-inflammatory cytokine release may comprise an intrinsic and early property of nascent Schwann cells, and that immune dysregulation may be an early contributor to CMT1A pathogenesis, as opposed to a secondary reaction. Finally, the broadest contribution of this study is a methodological one, in which all three reprogrammed Schwann cell models were utilized to demonstrate a converged phenotype. This approach offers a technical alternative to genome editing for disease hiPSC phenotype validation, and comprises a feasible model for future studies.
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Keywords
Charcot Marie Tooth, Hereditary Motor and Sensory Neuropathy, Schwann cells