The low survival rate of graft stem cells after transplantation into recipient tissue is a major obstacle for successful stem cell therapy. After transplantation into the site of spinal cord injury, the stem cells face not only hypoxia due to low oxygen conditions, but also a lack of nutrients caused by damaged tissues and poor vascular supply. To improve the survival of therapeutic stem cells after grafting into the injured spinal cord, we examined the effects of cotransplanting mouse neural stem cells (mNSCs) and adipose tissue-derived mesenchymal stem cells (AT-MSCs) on mNSC viability. The viability of mNSCs in coculture with AT-MSCs was significantly increased compared to mNSCs alone in an in vitro injury model using serum deprivation (SD), hydrogen peroxide (H(2)O(2)), and combined (SD + H(2)O(2)) injury mimicking the ischemic environment of the injured spinal cord. We demonstrated that AT-MSCs inhibited the apoptosis of mNSCs in SD, H(2)O(2), and combined injury models. Consistent with these in vitro results, mNSCs transplanted into rat spinal cords with AT-MSCs showed better survival rates than mNSCs transplanted alone. These findings suggest that cotransplantation of mNSCs with AT-MSCs may be a more effective transplantation protocol to improve the survival of cells transplanted into the injured spinal cord.