Date Published: August 12, 2015
Publisher: Public Library of Science
Author(s): Fahimeh Mirakhori, Bahman Zeynali, Hassan Rassouli, Ebrahim Shahbazi, Shiva Hashemizadeh, Sahar Kiani, Ghasem Hosseini Salekdeh, Hossein Baharvand, Jialin Charles Zheng.
A number of studies generated induced neural progenitor cells (iNPCs) from human fibroblasts by viral delivering defined transcription factors. However, the potential risks associated with gene delivery systems have limited their clinical use. We propose it would be safer to induce neural progenitor-like cells from human adult fibroblasts via a direct non-genetic alternative approach.
Here, we have reported that seven rounds of TAT-SOX2 protein transduction in a defined chemical cocktail under a 3D sphere culture gradually morphed fibroblasts into neuroepithelial-like colonies. We were able to expand these cells for up to 20 passages. These cells could give rise to cells that expressed neurons and glia cell markers both in vitro and in vivo.
These results show that our approach is beneficial for the genetic material-free generation of iNPCs from human fibroblasts where small chemical molecules can provide a valuable, viable strategy to boost and improve induction in a 3D sphere culture.
The unique capability of neural progenitor cells (NPCs) to induce regeneration in several animal models of neurological disorders  make them the best potential cell source for regenerative medicine. However, the low availability of reliable human NPC sources limits their validity for these treatments. The ideal cell source for cell-based therapies and their downstream use in drug discovery and regenerative medicine should be patient specific, easy to obtain and expand with controlled differentiation, have the capability to generate desired derivatives, as well as safety and non-tumorigenicity . Human NPCs can be generated from pluripotent stem cells (PSCs), however the remainder of even a few undifferentiated PSCs in the resultant cell mixture can cause tumor formation after transplantation [3,4]. To address this problem, tremendous efforts have been undertaken to convert one cell type directly into induced neural progenitor cells (iNPCs) from accessible cell types such as skin fibroblasts by forced expression of defined transcription factors [5–9].
In this study we developed a protocol to generate genetic material-free iNPCs directly from human fibroblasts. This was achieved by SOX2 protein transduction in combination with a cocktail of SM in a 3D sphere culture.