Stem cell-based cellular replacement strategies following traumatic brain injury (TBI)

Given the limited capacity of the central nervous system for self-repair, the use of stem cells holds an enormous potential in cell replacement therapy following traumatic brain injury and has thus received a great deal of scientific and public interest in recent years. During the past decade, several stem/progenitor cell types and lines from various sources such as embryonic rodent and human stem cells, immortalized progenitor cells, bone marrow derived cells or even post-mitotic neurons derived from human teratocarcinoma cells have been assessed for their potential to improve neurofunctional and behavioural outcome after transplantation into the experimentally injured brain. A number of studies indicate that cells engrafted into the injured brain can survive and, at least in part, may reverse behavioural dysfunction and histomorphological damage. Although these results emphasized their potential therapeutic role in traumatic brain injury, the detailed mechansim on how stem cells generate their mode of action, e.g. via integration into surviving neuronal circuits, local trophic support, or modification of the local mircoenvironment to enhance endogenous regeneration and potection remain yet to be identified. A review on current pre-clinical knowledge with respect to cellular replacement into the experimentally injured brain is presented.