Fusion of Human Fetal Mesenchymal Stem Cells with "Degenerating" Cerebellar Neurons in Spinocerebellar Ataxia Type 1 Model Mice

PLoS One. 2016 Nov 1;11(11):e0164202. doi: 10.1371/journal.pone.0164202. eCollection 2016.

Abstract

Mesenchymal stem cells (MSCs) migrate to damaged tissues, where they participate in tissue repair. Human fetal MSCs (hfMSCs), compared with adult MSCs, have higher proliferation rates, a greater differentiation capacity and longer telomeres with reduced senescence. Therefore, transplantation of quality controlled hfMSCs is a promising therapeutic intervention. Previous studies have shown that intravenous or intracortical injections of MSCs result in the emergence of binucleated cerebellar Purkinje cells (PCs) containing an MSC-derived marker protein in mice, thus suggesting a fusion event. However, transdifferentiation of MSCs into PCs or transfer of a marker protein from an MSC to a PC cannot be ruled out. In this study, we unequivocally demonstrated the fusion of hfMSCs with murine PCs through a tetracycline-regulated (Tet-off) system with or without a Cre-dependent genetic inversion switch (flip-excision; FLEx). In the FLEx-Tet system, we performed intra-cerebellar injection of viral vectors expressing tetracycline transactivator (tTA) and Cre recombinase into either non-symptomatic (4-week-old) or clearly symptomatic (6-8-month-old) spinocerebellar ataxia type 1 (SCA1) mice. Then, the mice received an injection of 50,000 genetically engineered hfMSCs that expressed GFP only in the presence of Cre recombinase and tTA. We observed a significant emergence of GFP-expressing PCs and interneurons in symptomatic, but not non-symptomatic, SCA1 mice 2 weeks after the MSC injection. These results, together with the results obtained using age-matched wild-type mice, led us to conclude that hfMSCs have the potential to preferentially fuse with degenerating PCs and interneurons but not with healthy neurons.

MeSH terms

  • Animals
  • Ataxin-1 / metabolism*
  • Cell Differentiation / physiology
  • Cell Transdifferentiation / physiology
  • Cerebellum / cytology*
  • Cerebellum / metabolism
  • Disease Models, Animal
  • Fetal Stem Cells / cytology
  • Fetal Stem Cells / metabolism
  • Fetus / cytology*
  • Fetus / metabolism
  • Humans
  • Mesenchymal Stem Cell Transplantation / methods
  • Mesenchymal Stem Cells / cytology*
  • Mesenchymal Stem Cells / metabolism
  • Mice
  • Mice, Transgenic
  • Neurons / cytology*
  • Neurons / metabolism
  • Purkinje Cells / cytology
  • Purkinje Cells / metabolism

Substances

  • Ataxin-1
  • Atxn1 protein, mouse

Grant support

This work was supported by a grant from the Funding Program for Next Generation World-Leading Researchers (LS021), Grant-in-Aid for Scientific Research on Innovative Areas (“Brain Environment”) (KAKENHI, Grant Number 26111701), the Naito Foundation, Gunma University Initiative for Advanced Research (GIAR) to H. Hirai and postgraduate scholarship (No. 110049) to F. Huda from the Ministry of Education, Science, Sports and Culture of Japan (MEXT). JKYC received salary support from the National Medical Research Council, Singapore (NMRC/CSA/043/2012).