Traumatic brain injury is a world-leading cause of disability. Current treatments are not sufficient to promote neurological recovery. Intracerebral transplantation of allogeneic mesenchymal stem cells, specifically SB623, has shown promise in achieving better neurological recovery compared with a sham surgery group in the STEMTRA trial. However, the optimal location for cell transplantation remains unclear, as transplanted lesions vary between patients. This study aimed to explore the relationship between functional recovery and the location of transplanted lesions. This study included all Japanese subjects from the STEMTRA trial who were assigned to the cell transplantation group. Functional recovery was assessed by the difference in Fugl-Meyer Motor Scale (FMMS) scores between the screening period and 24 or 48 weeks post-transplantation. An FMMS score improvement of >
8 was defined as an improved group. Lesions responsible for motor deficits were categorized into three groups: motor cortex (Cortex), deep white matter (DWM), or both (Cortex and DWM). Data on the 15 transplanted sites per patient were obtained from surgical navigation software, and the distance from the damaged area to the transplanted sites was calculated. Twelve patients were included in this