Evaluating Leucine, Isoleucine, and Valine Ratios in Mixed Cortical Cell Cultures Following Cortical Trauma: An In Vitro Assessment.

Background/Objectives: Traumatic brain injury (TBI) remains the most common cause of morbidity and mortality in adolescents and adults. Although numerous animal and human studies have demonstrated the beneficial effects of branched-chain amino acids (BCAA) treatment on various models of brain injury, the optimal concentration and mechanism of action have not been elucidated. Methods: Based on our prior work, we hypothesized that a 2:1:1 ratio of BCAAs promotes neuronal regrowth and repair. Using in vitro mixed cortical cultures (composed of CNS cells, including neuronal and glial cells), we recapitulated the mechanical damage induced by TBI using the scratch assay model. We evaluated various concentrations of BCAA to promote the regrowth of CNS cells after mechanical damage. Results: A 2:1:1 ratio of leucine: isoleucine: valine was observed to yield superior regrowth rates at the 48 h time point across various concentrations when compared to a 1:1:1 ratio and even a 4:1:1 ratio. In addition, both 2:1:1 and 4:1:1 ratios offered multiple instances of accelerated regrowth, where less than 5% of the wound remained unhealed. Conclusions: The importance of leucine ratios in the context of BCAA treatment for TBI was demonstrated by the superior CNS cell regrowth offered by the 2:1:1 ratio.