Bone marrow cells migrate to the heart and skeletal muscle and participate in tissue repair after Trypanosoma cruzi infection in mice.

Infection by Trypanosoma cruzi, the aetiological agent of Chagas disease, causes an intense inflammatory reaction in several tissues, including the myocardium. We have previously shown that transplantation of bone marrow cells (BMC) ameliorates the myocarditis in a mouse model of chronic Chagas disease. We investigated the participation of BMC in lesion repair in the heart and skeletal muscle, caused by T. cruzi infection in mice. Infection with a myotropic T. cruzi strain induced an increase in the percentage of stem cells and monocytes in the peripheral blood, as well as in gene expression of chemokines SDF-1, MCP1, 2, and 3 in the heart and skeletal muscle. To investigate the fate of BMC within the damaged tissue, chimeric mice were generated by syngeneic transplantation of green fluorescent protein (GFP(+) ) BMC into lethally irradiated mice and infected with Trypanosoma cruzi. Migration of GFP(+) BMC to the heart and skeletal muscle was observed during and after the acute phase of infection. GFP(+) cardiomyocytes and endothelial cells were present in heart sections of chimeric chagasic mice. GFP(+) myofibres were observed in the skeletal muscle of chimeric mice at different time points following infection. In conclusion, BMC migrate and contribute to the formation of new resident cells in the heart and skeletal muscle, which can be detected both during the acute and the chronic phase of infection. These findings reinforce the role of BMC in tissue regeneration.