Direct conversion of human fibroblasts into dopaminergic neural progenitor-like cells using TAT-mediated protein transduction of recombinant factors

Recent progress in the generation of induced neural progenitor cells (iNPCs) holds tremendous potential for regenerative medicine. However, a major limitation is the lack of a reliable source for cell replacement therapy in neurological diseases such as Parkinson's disease (PD). Here, we show that the combination of small molecules (SM) and TAT-mediated protein transduction of SOX2 and LMX1a in a 3D sphere culture directly convert human fibroblasts to induced dopaminergic neural progenitor-like cells (iDPCs). The generated iDPCs expressed various NPC markers (SOX2, PAX6, NESTIN, OLIG2) and midbrain progenitor markers (EN1, LMX1a, FOXA2, WNT1) as detected by immunostaining and real-time PCR. Following differentiation, the majority of cells expressed neuronal dopaminergic markers as indicated by co-expression of TH with NURR1, and/or PITX3. We found that SOX2 and LMX1a TAT-mediated protein transduction in the combination of SM could directly convert human fibroblasts to self-renewal iDPCs. In conclusion, to our best knowledge, this is the first report of generation of safe DPCs and may suggest an alternative strategy for cell therapy for the treatment of neurodegenerative disorders.