Trans-differentiated neurons offer a way to bypass the tumorigenicity risk associated with passing through a pluripotency state. This method allows lineage reprogramming as in directly converting a somatic cell type into another through transgenic expression of transcription factors or miRNAs. On the other hand, the procedure of re-differentiating iPSCs into specific cell types is considered lengthy, costly and arduous. In addition to that, having multiple stages before reaching the intended outcome may lower the efficiency of the generated cell type. So far, in this context, trans-differentiation seems to be also an interesting path in research that also offers the same concept of therapeutic approaches and disease modeling as iPSCs. Trans-differentiated cells show no tumorigenicity when transplanted in vivo, plus these cells show similar functionality to cells derived from iPSCs (Lopez-Leon et al., 2014; Hou and Lu, 2016). In the presence of an insult or a lesion, or even in AD animal models, glial cells can be successfully transformed to functional neurons by single transcription factor intervention (Guo et al., 2014). For example, in the presence of SOX2 in the injured
