Abstract: This invention provides technology for transdifferentiating cells from one cell type to another. The cells are cultured with one or more vector-free gene regulator oligonucleotides concurrently or in succession, and then harvested when cell markers or the morphology of the culture shows that transdifferentiation is complete. Suitable gene regular oligonucleotides include microRNAs and messenger RNAs that encode a differentiation factor. Conditions for transdifferentiation can be optimized by dividing cells into different culture chambers of a microfluidic device. Cells are cultured with different additives in each chamber, and then compared. Transdifferentiated cells produced according to this invention can provide a consistent source of tissue for use in regenerative medicine.