Shining Light on the Sprout of Life: Optogenetics Applications in Stem Cell Research and Therapy.

Optogenetics is the integration of genetics and optics to achieve gain or loss of function of well-defined events in specific cells of living tissue. As a versatile tool, upon light illumination, it allows fast control of precisely defined events in biological systems from single cell to different parts of whole tissue in freely moving animals. Taking advantage of this method, a multitude of studies have been published to understand brain functions and dysfunctions. Although from the beginning, it has been used to target neurons within the neural networks and to understand how specific neurons contribute to brain function, it gradually has been extended to other fields of biology such as stem cell research and therapy. With a combination of optogenetics and stem cells, new opportunities were opened up in stem cell biology and also its integration in new circuit as a cell-based treatment strategy for more common disorders like neurodegenerative and cardiovascular one. Recently, some studies showed that engineered stem cells expressing exogenous light-activated opsins can be used in stem cell biology including tracking the differentiation of stem cells, functional analysis of embryonic stem cell-derived graft, and testing the functional integration of induced pluripotent stem cell-derived neurons. With the advent of non-invasive approach, such as transcranial excitation or inhibition, optogenetics also holds promise for non-invasive control of engineered stem cell.