As our world continues to evolve, the field of regenerative medicine f- lows suit. Although many modern day therapies focus on synthetic and na- ral medicinal treatments for brain repair, many of these treatments and prescriptions lack adequate results or only have the ability to slow the p- gression of neurological disease or injury. Cell therapy, however, remains the most compelling treatment for neurodegenerative diseases, disorders, and injuries, including Parkinson's disease, Huntington's disease, traumatic brain injury, and stroke, which is expanded upon in more detail in Chapter 1 by Snyder and colleagues. Cell therapy is also unique in that it is the only therapeutic strategy that strives to replace lost, damaged, or dysfunctional cells with healthy ones. This repair and replacement may be due to an administration of exogenous cells itself or the activation of the body's own endogenous reparative cells by a trophic, immune, or inflammatory response to cell transplantation. However, the precise mechanism of how cell therapy works remains elusive and is c- tinuing to be investigated in terms of molecular and cellular responses, in particular. Moreover, Chapter 11 by Emerich and associates, discusses some of the possibilities of cell immunoisolation and the potential for treating central nervous system diseases.