**1. Introduction**

In current clinical practice, tissue plasminogen activator (t-PA) is the gold standard drug to be administred within three hours after the onset of cerebral infarction. In the near future, it will become acceptable to administer it within 4.5 hours of onset. Even if t-PA administration cannot be utilized for cerebral infaction patients because of time window limitations, the intravascular technique using the Merci(R) retreiver and the Penumbra(R) system can be applied to some patients with cerebral infarction. Not all cerebral infarction patients can be saved by these clinical therapeutic methods. Despite surviving the acute phase of cerebral infarction as a result of these clinical therapeutic methods, some patients suffer from permanent hemipa‐ resis in the chronic phase. It is for this reason that regenerative medicine must play more important role in solving this problem.

We have two types of regenerative medicine approaches to patients with neurological diseases such as cerebral infarction and Parkinson's disease. The first approach involves exogenous stem cells for stem cell transplantation [1-3], and the second involves the enhancement of endogenous stem cells. In terms of neural stem cell transplantation (allogenic transplantation), we demonstrated the neuroprotective effect of adult neural stem and progenitor cells that were modified to secrete Glial cell line–derived neurotropic factor (GDNF) in a transient ischemia model of rats [4]. However, we have not demonstrated the same effect by autologous trans‐ plantaion. Stem cells were transplanted in the acute stage of an ischemia animal model in many studies, which showed the neuroprotective effect of stem cell transplantation. It is difficult to show the same effect of stem cell transplantation in the chronic phase of ischemia. As a result, if we want to show the same effect by autologous stem cell transplantation, we must transplant autologous stem cells in an acute-stage ischea model of rats. Unfortunately, we do not yet have a technique to immediately expand autologous adult neural stem cells. Our previous experi‐

© 2013 Kameda; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ment showed that it took several weeks to obtain a sufficient number of autologous adult neural stem cells [5]. Many researchers have pointed out that the effect of these stem cell transplantations is derived not from cell replacement, which is the original purpose of stem cell transplantation, but mainly from the trophic effect brought about by transplanted stem cell secretions. Generally speaking, compared to exogenous stem cell transplantation, the enhancement of endogenous stem cells is expected to be less invasive. Previous reports showed that an enriched environment and running enhanced endogenous stem cell generation [6] and that trophic factors produced by these enhanced endogenous stem cells had a neuroprotective effect on these neurological disorders. Deep brain stimulation (DBS) is one of the gold standards of treatment for Parkinson's disease (PD) in current clinical pratice. Recent reports have showed that DBS can enhance endogenous stem cells in a PD model of rats [7]. Although phase 3 or 4 clinical trials with DBS for depression and obesity and epidural electrical stimu‐ lation for pain are currently ongoing, they are not being performed for regenerative medicine (http://clinicaltrials.gov). Based on this report, we examined whether electrical stimulation has therapeutic potential for CNS diseases by activating endogenous stem cells.
