Transplantation of Human-Induced Pluripotent Stem Cell-Derived Neural Precursors into Early-Stage Zebrafish Embryos.

Induced pluripotent stem cells (iPS cells) generated from somatic cells through reprogramming hold great promises for regenerative medicine. However, how reprogrammed cells survive, behave in vivo, and interact with host cells after transplantation still remains to be addressed. There is a significant need for animal models that allow in vivo tracking of transplanted cells in real time. In this regard, the zebrafish, a tropical freshwater fish, provides significant advantage as it is optically transparent and can be imaged in high resolution using confocal microscopy. The principal goal of this study was to optimize the protocol for successful short-term and immunosuppression-free transplantation of human iPS cell-derived neural progenitor cells into zebrafish and to test their ability to differentiate in this animal model. To address this aim, we isolated human iPS cell-derived neural progenitor cells from human fibroblasts and grafted them into (a) early (blastocyst)-stage wild-type AB zebrafish embryos or (b) 3-day-old Tg(gfap:GFP) zebrafish embryos (intracranial injection). We found that transplanted human neuronal progenitor cells can be effectively grafted and that they differentiate and survive in zebrafish for more than 2 weeks, validating the model as an ideal platform for in vivo screening experiments. We conclude that zebrafish provides an excellent model for studying iPS cell-derived cells in vivo.

Effect of homocysteine on survival of human glial cells.

Several neurodegenerative conditions, such as Alzheimer's disease and Parkinson's disease, or vascular dementia and cognitive impairment, are associated with mild hyperhomocysteinemia. Hyperhomocysteinemia is defined as an increase of the homocysteine (Hcy) level beyond 10 microM. Although the adverse effect of Hcy on neurons is well documented, knowledge about the impact of this amino acid on glial cells is missing. Therefore, with the aim to evaluate the neurotoxic properties of Hcy on glial cells, we used a glioblastoma cell line as a study model. The viability of cells was assayed biochemically and cytologically. At a concentration around 50 microM in the culture medium D,L-Hcy induced cell death. It is noteworthy that Hcy induces cell death of human glial cells at concentrations encountered during mild hyperhomocysteinemia. Therefore, we propose that Hcy-induced impairment of neuronal functions along with damage of glial cells may contribute to the etiopathogenesis of neurodegenerative diseases associated with hyperhomocysteinemia.