Venkata Sai Sruthi's lectures
Improved methodologies for genetic conversion of human fibroblasts to neurons
Genetic cell fate manipulation can be used to convert one cell type to another, which facilitates the production of personalized and customized human neurons for basic science applications and disease modeling. Genetic conversions often start with accessible cell types like fibroblasts, which are converted to neurons using multiple lentivirus vectors that encode neurogenic genes, such as Ascl1 and Ngn2; furthermore, for doxycycline (dox) inducibility, another vector is used to deliver a dox-dependent transcriptional regulator (e.g. rtTA or TetR). Such direct cell fate conversion approaches have the advantage of retaining some epigenetic marks, but somatic cells like fibroblasts often grow slowly, and the use of multiple viral vectors decreases conversion efficiencies. To address these limitations, we tested a range of media formulations and found that supplementing serum-based fibroblast media with basic fibroblast growth factor improved growth by 3-fold. We also found that co-expression of Ascl1 and Ngn2 from a single lentivirus vector improved neuronal conversion by approximately 45% compared to the delivery of Ascl1 and Ngn2 on separate vectors. These improvements increase both neuronal conversion efficiency and potential neuronal yield of this fibroblast-to-neuron conversion platform. We are currently developing a self-inactivating "all-in-one" lentivirus, which will express dox-inducible Ascl1-P2A-Ngn2 along with TetR and a selectable marker to isolate pure neuronal populations for studies of human neurobiology and to model disorders of the brain.