BACKGROUND Chagas disease is a public health problem caused by infection with the protozoan
Trypanosoma cruzi
. There is
currently no effective therapy for Chagas disease. Although there is some evidence for the beneficial effect of bone marrow-derived
cells in chagasic disease, the mechanisms underlying their effects in the heart are unknown. Reports have suggested that bone marrow
cells are recruited to the chagasic heart; however, studies using chimeric mouse models of chagasic cardiomyopathy are rare.
OBJECTIVES The aim of this study was to investigate the migration of bone marrow cells to the heart after
T. cruzi infection in a
model of chagasic disease in chimeric mice.
METHODS To obtain chimerical mice, wild-type (WT) C57BL6 mice were exposed to full body irradiation (7 Gy), causing bone
marrow ablation. Then, bone marrow cells from green fluorescent protein (GFP)-transgenic mice were infused into the mice.
Graft effectiveness was confirmed by flow cytometry. Experimental mice were divided into four groups: (i) infected chimeric
(iChim) mice; (ii) infected WT (iWT) mice, both of which received 3 × 10
4 trypomastigotes of the Brazil strain; (iii) non-infected
chimeric (Chim) mice; and (iv) non-infected WT mice.
FINDINGS At one-month post-infection, iChim and iWT mice showed first degree atrioventricular block with decreased heart
rate and treadmill exercise parameters compared to those in the non-infected groups.
MAIN CONCLUSIONS iChim mice showed an increase in parasitaemia, myocarditis, and the presence of amastigote nests in
the heart tissue compared to iWT mice. Flow cytometry analysis did not detect haematopoietic progenitor cells in the hearts of
infected mice. Furthermore, GFP+ cardiomyocytes were not detected in the tissues of chimeric mice.