Clot-derived contaminants in transplanted bone marrow mononuclear cells impair the therapeutic effect in stroke
Okinaka Y, Kikuchi-Taura A, Takeuchi Y, Ogawa Y, Boltze J, Gul S, Claussen C, Taguchi A
The beneficial effects of bone marrow mononuclear cell (BM-MNC) transplantation in preclinical experimental stroke have been reliably demonstrated. However, only overall modest effects in clinical trials were observed. We have investigated and reported a cause of the discrepancy between the preclinical and clinical studies. We found that the transplanted contaminants were trapped at the peristroke area, which were associated with microglial/macrophage activation. Clot-derived contaminants in transplanted BM-MNC nullify therapeutic effects in experimental stroke. This may explain neutral results in clinical trials, especially in those using automated stem cell separators that lack the ability to remove clot-derived contaminants.