Morii, E. | bioRxiv Science

bioRxiv2021

Myasthenia gravis-specific aberrant neuromuscular gene expression by medullary thymic epithelial cells in thymoma

Myasthenia gravis (MG) is a neurological disease caused by autoantibodies against neuromuscular-associated proteins. While MG is frequently developed in thymoma patients, the etiologic factors for MG are not well understood. Here, by constructing a comprehensive atlas of thymoma using bulk and single-cell RNA-seq, we identified ectopic expression of neuromuscular molecules in MG-associated thymoma (MG-thymoma). These molecules were originated from a distinct subpopulation of medullary thymic epithelial cells (mTECs), which we named neuromuscular mTECs (nmTECs). MG-thymoma also exhibited microenvironments dedicated to autoantibody production, including ectopic germinal center formation, T follicular helper cell accumulation, and type 2 conventional dendritic cell migration. Cell-cell interaction analysis also predicted the interaction between nmTECs and T/B cells via CXCL12-CXCR4. The enrichment of nmTECs presenting neuromuscular molecules within MG-thymoma was further confirmed by immunohistochemically and by cellular composition estimation from MG-thymoma transcriptome. Altogether, this study suggests that nmTECs play a significant role in MG pathogenesis via ectopic expression of neuromuscular molecules.

immunology↗

bioRxiv2021

Evaluation of the Efficacy and Safety of a Clinical Grade Human Induced Pluripotent Stem Cell-Derived Cardiomyocyte Patch: A Pre-Clinical Study

AimsCardiomyocyte-derived induced pluripotent stem cells (iPSCs) may represent a promising therapeutic strategy for severely damaged myocardium. This study aimed to assess the efficacy and safety of clinical grade human iPSC-derived cardiomyocyte (hiPSC-CM) patches and conduct a pre-clinical proof-of-concept analysis. Methods and resultsA clinical grade hiPSC line was established from peripheral blood mononuclear cells collected from a healthy volunteer homozygous for human leukocyte antigens and differentiated into cardiomyocytes using cytokines and chemical compounds. hiPSC-CMs were cultured on temperature-responsive culture dishes to fabricate the hiPSC-CM patch. The hiPSC-CMs expressed cardiomyocyte-specific genes and proteins while electrophysiological analyses revealed that hiPSC-CMs were similar to the human myocardium. In vitro safety studies using cell growth, soft agar colony formation, and undifferentiated cell assays indicated that tumourigenic cells were not present. Moreover, no genomic mutations were discovered using whole genome and exome sequencing analysis. Tumour formation was not detected in an in vivo tumourigenicity assay using NOG mice. General toxicity tests also showed no adverse events due to hiPSC-CM patch transplantation. An efficacy study using a porcine model of myocardial infarction demonstrated significantly improved cardiac function with angiogenesis and a reduction in interstitial fibrosis, which was enhanced by cytokine secretion from hiPSC-CM patches after transplantation. No lethal arrhythmias were observed. ConclusionhiPSC-CM patches show promise for future translational research and clinical trials for ischaemic heart failure. One-sentence summaryThis pre-clinical study provides a proof-of-concept of the safety and efficacy of hiPSC-CM patches for the treatment of heart failure. Translational PerspectiveRegenerative therapy using cells and tissues is attractive as a novel approach for treating severe heart failure. We focused on human iPS cell-derived cardiomyocytes (hiPSC-CMs) as a cell source. Using basic research, the characteristics of hiPSC, hiPSC-CMs, and hiPSC-CM patches were determined in vitro and in vivo. We also conducted a pre-clinical study using a porcine model of myocardial infarction that confirmed the safety and efficacy of the hiPSC-CM patch, highlighting its potential for clinical application.

cell biology↗