Authors: Maryam Rahman, MD, FAANS; Maryam Rahman, MD; Farhad Dastmalchi, DVM; Elias Sayour, MD, PhD; Changlin Yang, MD, PhD; Anjelika Vashkevich, RN; Alex Vlasak, BS; Megan Saia; Duane Mitchell, MD, PhD (Gainesville, FL)
We have previously demonstrated that increasing dendritic cell (DC) migration after DC vaccination improves survival in patient with glioblastoma (GBM). In this study, we hypothesized that a novel metabolite, sarcosine, would increase DC migration and outcomes in the treatment of brain tumors.
Human and murine dendritic cells were cultured from peripheral blood mononuclear cells (PBMCs) as previously described. Cells were loaded with sarcosine by adding sarcosine to the media and electroporating cells. Migration was measured in vitro, in vivo and murine tumor models were utilized to test efficacy of sarcosine loaded and control DC vaccines. The mechanism of sarcosine on migration was tested using PCR and blocking antibodies.
Human and murine DCs loaded with sarcosine did not have changes in cell phenotype, cell cycle or cell growth. Both human and murine DCs demonstrated significantly increased migration in vitro when loaded with sarcosine. In vivo, sarcosine loaded DCs had significantly increased homing to the local lymph nodes and to the spleen within 48 hours of vaccination compared to control DCs. Intracranial and flank tumor bearing animals had improved tumor control and survival when treated with sarcosine loaded DCs compared to control DCs. PCR analysis revealed an upregulation of CX3CL1 in sarcosine loaded cells. When human or murine DCs loaded with sarcosine were exposed to CX3CL1 blocking antibody, their increased migration was abrogated.
Sarcosine increases the migration of DCs via the CX3CL1 pathway. This increase in DC migration also results in a more robust anti-tumor immune response and better tumor control in a murine brain tumor model. Sarcosine is non toxic to murine and human DCs. Further studies in human subjects are necessary to determine the utility of this treatment platform.