Bone marrow cell migration to the heart in a chimeric mouse model of acute chagasic disease

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 × 104 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.

Isolamento, cultivo e caracterização de células derivadas de cardioesferas de camundongos CD1 / Isolation, culture and characterization of cardiospheres-derived cells from CD1 mice

No Brasil, como em todo o mundo, as doenças cardiovasculares têm sido uma das principais causas de morte. A alta mortalidade e as poucas alternativas terapêuticas para esta doença têm estimulado a investigação no campo das células estaminais. Recentemente, alguns grupos têm mostrado a presença de células-tronco/progenitoras residentes no coração. Estas poderiam ser cultivadas diretamente a partir de tecidos cardíacos produzindo aglomerados esféricos denominados Cardioesferas estas, contém células proliferativas que dão origem, após o plaqueamento, a uma população heterogênea denominada: células derivadas de cardioesferas (CDCs). O objetivo deste estudo foi isolar, cultivar e caracterizar as CDCs de camundongos da linhagem CD1. Para isto, as células primárias foram isoladas a partir de corações de camundongos adultos da linhagem CD1 após a digestão de pequenos fragmentos do órgão em 420U/ml utilizando colagenase tipo II por 20 minutos 37°C. Nas análises por Citometria de Fluxo (FACS) foram observadas baixa expressão das moléculas de CD19 (0,4%), CD45 (0,5%) e CD90 (4,77%), e alta expressão das moléculas CD73 (71,47%), CD105 (25,1%), CD14 (25,17%). Nos ensaios de imunofluorescência foi possível observar a expressão das proteínas no citoplasma dos cardiomiócitos: vimentina, desmina e alfa actina de músculo liso, além da expressão do filamento intermediário nestina. Ao analisar a expansão celular por population doubling time foi observado que as CDCs duplicaram sua população original em cerca de 1,8 dias. Estes resultados sugerem que as CDCs isoladas a partir de camundongos da linhagem CD1, são células que apresentam características de células mesenquimais, constituindo uma população celular a ser testada nos estudos em terapias celulares. Estes resultados, motiva a estabelecer protocolos mais efetivos a fim de investigar possíveis efeitos parácrinos benéficos, bem como o potencial angiogênico e cardiogênico destas células.

In Brazil, as elsewhere in the world, cardiovascular diseases have been a major cause of death. The high mortality and few therapeutic alternatives for this disease have stimulated research in the field of stem cells. Recently, some groups have shown the presence of stem cells residents at heart. These could be grown directly from tissue cardiac producing spherical agglomerates called cardiospheres these contains proliferating cells that give rise after plating, a heterogeneous population named: cells derived from cardiospheres (CDC). Our goal in this study was to isolate and characterize the cultivar CDC CD1 strain of mice. For this purpose, primary cells were isolated from hearts of adult mice of the CD1 strain after digestion of the organ into small fragments using 420U/ml collagenase type II for 20 minutes 37 ° C. In analysis by Flow Cytometry (FACS) were observed low expression of CD19 molecules (0.4%), CD45 (0.5%) and CD90 (4.77%), and high expression of the molecules CD73 (71.47%), CD105 (25.1%), CD14 (25.17%). In the immunofluorescence assays was possible to observe the expression of the proteins in the cytoplasm of cardiomyocytes: vimentin, desmin and smooth muscle alpha actin, and expression of the intermediate filament nestin. By analyzing the cellular expansion team for Population doubling was observed that the original CDC doubled its population in about 1.8 days. These results suggest that CDCs isolated from CD1 mouse strain to be have characteristics of mesenchymal cells, constituting a potential population studied in cellular therapies, motivating us to establish more effective protocols to investigate possible beneficial paracrine effects and their angiogenic and cardiogenic potential.