“…Besides TFs, small molecules are also able to manipulate cell fate choices. − Such molecules typically act by modulating cell signaling cascades, epigenetic mechanisms, and metabolic pathways. ,, In combination with TFs, certain small molecules can also improve reprogramming and forward programming efficiencies. − Overexpression of the Neurogenin-2 TF together with small molecules, for instance retinoic acid, enhances the yield of multiple subtypes of stem cell-derived motor neurons . Additionally, combinations of small molecules can also induce reprogramming independent of TFs and thereby overcome the clinical and translational concerns associated with exogenous gene delivery. ,, Moreover, small molecules can easily cross the cell membrane, are generally inexpensive to synthetize and preserve, and their dosing can be tightly controlled in a straightforward manner. ,,− These properties make small molecules attractive to be used in patterned and gradient-generating microfluidic platforms. In general, an optimal multimodal neuronal cell niche engineering platform should be able to incorporate the use of both TFs and small molecules for high yield and robust forward programming, while also supporting the utilization of neurotrophic and axonal attractant-repellent gradients to control neuronal cell polarity.…”