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 adult spinal cord, astrocytes convert to double cortin (DCX) positive neuroblasts (Lau et al., 2014). However, the major limitation for trans-differentiation to be a therapeutic approach is that the obtained population of induced neurons has little to no proliferation rate, therefore directly restricting the efficiency and expansion of this technique (Hou and Lu, 2016). Hence, a better investment for a drug or therapeutic or modeling purposes would still be iPSCs, but this does not overthrow the importance of trans-differentiation. The research in this field is still young but so vivid and fertile that we can witness iPSCs applied in neurodegenerative diseases treatments in not the so far future. Yet, until this day, there is no recorded iPSCs treatment application on humans (Trounson and DeWitt, 2016).
