Human cord blood mononuclear cells decrease cytokines and inflammatory cells in acute myocardial infarction.

We investigated whether human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal progenitor cells, can limit myocardial cytokine expression and inflammatory cell infiltration in acute myocardial infarction. We permanently ligated the left coronary artery of rats and injected into the myocardium either Isolyte or 4 x 10(6) HUCBC in Isolyte and measured myocardial cytokines with antibody arrays at 2, 6, 12, 24, and 72 hours after infarction. We then measured with flow cytometry myocardial macrophages, neutrophils and lymphocytes at 12, 24, and 72 hours after infarctions in rats treated with either intramyocardial Isolyte or 4 x 10(6) HUCBC. In the Isolyte-treated hearts, between 2 and 12 hours after myocardial infarction, tumor necrosis factor-alpha increased from 6.7 +/- 0.9% to 52.3 +/- 4.7%, monocyte chemoattract protein increased from 9.5 +/- 1.2% to 39.8 +/- 2.1%, fractalkine increased from 11 +/- 1.5% to 28.1 +/- 1.3%, ciliary neurotrophic factor increased from 12.1 +/- 0.02% to 25.9 +/- 1.1%, macrophage inflammatory protein increased from 10.3 +/- 1.5% to 23.9.0 +/- 1.4%, interferon-gamma increased from 8.7 +/- 0.4% to 26.0 +/- 1.6%, interleukin-1beta increased from 6.1 +/- 0.04% to 19.0 +/- 1.2%, and IL-4 increased from 5.9 +/- 0.03% to 15 +/- 1.5% (all p < 0.001 compared with controls). The concentrations of fractalkine remained significantly increased at 72 hours after acute infarction. In contrast, the myocardial concentrations of these cytokines did not significantly change in HUCBC treated hearts at 2, 6, 12, 24, or 72 hours after infarction. The percentage of neutrophils increased from 0.04 +/- 0.2%/50,000 heart cells in the controls to 5.3 +/- 1.2%/50,000 heart cells 12 hours after infarction in Isolyte-treated hearts but averaged only 1.3 +/- 0.7%/50,000 heart cells in HUCBC treated hearts (p < 0.02). Thereafter, the percentages of neutrophils rapidly decreased at 24 and at 72 hours after infarction and averaged 0.6 +/- 0.2%/50,000 heart cells at 72 hours after infarction in Isolyte-treated hearts in contrast to 0.2 +/- 0.1%/50,000 cells in HUCBC hearts (p < 0.05). Moreover, the percentages of neutrophils at 24 and 72 hours in HUCBC hearts were not significantly different from controls. At 24 hours post infarction, the percentage of CD3 and CD4 lymphocytes were 10.7 +/- 1.4% and 6.3 +/- 1.1%/50,000 cells in Isolyte hearts in comparison with only 4.9 +/- 0.8% and 2.9 +/- 0.5% in HUCBC hearts (p < 0.005 for Isolyte versus HUCBC). The percentage of CD11b macrophages was 2.8 +/- 0.3% in Isolyte hearts and 1.9 +/- 0.2% in HUCBC treated hearts (p < 0.05). At 72 hours after infarction, the percentage of CD3 and CD4 lymphocytes averaged 8.0 +/- 1.1% and 5.1 +/- 0.8%/50,000 heart cells in Isolyte hearts in comparison with only 4.1 +/- 0.5% and 2.3 +/- 0.4%/50,000 heart cells in the HUCBC treated infarctions (p < 0.005). Left ventricular infarct sizes in Isolyte-treated hearts at 72 hours post infarction averaged 15.7 +/- 1.4% of the left ventricular muscle area in contrast to HUCBC treated infarctions that averaged 6.9 +/- 1.4% of the left ventricular muscle area (p < 0.02). Moreover in rats followed for 2 months post infarction, the LV ejection fractions decreased to 65.4 +/- 1.9% and 69.1 +/- 1.9% at 1 and 2 months after infarction in Isolyte-treated hearts and were significantly different from HUCBC treated hearts that averaged 72.1 +/- 1.3% and 75.7 +/- 1.4% (both p < 0.02). The present experiments suggest that an important mechanism whereby HUCBC limit infarct size and improve left ventricular ejection fraction is by significantly limiting inflammatory cytokines and inflammatory cells in infarcted myocardium.

Human cord blood cells and myocardial infarction: effect of dose and route of administration on infarct size.

There is no consensus regarding the optimal dose of stem cells or the optimal route of administration for the treatment of acute myocardial infarction. Bone marrow cells, containing hematopoietic and mesenchymal stem cells, in doses of 0.5 x 10(6) to >30 x 10(6) have been directly injected into the myocardium or into coronary arteries or infused intravenously in subjects with myocardial infarctions to reduce infarct size and improve heart function. Therefore, we determined the specific effects of different doses of human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal stem cells, on infarct size. In order to determine the optimal technique for stem cell administration, HUCBC were injected directly into the myocardium (IM), or into the LV cavity with the ascending aorta transiently clamped to facilitate coronary artery perfusion (IA), or injected intravenously (IV) in rats 1-2 h after the left anterior coronary artery was permanently ligated. Immune suppressive therapy was not given to any rat. One month later, the infarct size in control rat hearts treated with only Isolyte averaged 23.7 +/- 1.7% of the LV muscle area. Intramyocardial injection of HUCBC reduced the infarct size by 71% with 0.5 x 10(6) HUCBC and by 93% with 4 x 10(6) HUCBC in comparison with the controls (p < 0.001). Intracoronary injection reduced the infarction size by 47% with 0.5 x 10(6) HUCBC and by 80% with 4 x 10(6) HUCBC (p < 0.001), and IV HUCBC reduced infarct size by 51% with 0.5 x 10(6) and by 75-77% with 16-32 million HUCBC (p < 0.001) in comparison with control hearts. With 4 x 10(6) HUCBC, infarction size was 65% smaller with IM HUCBC than with IA HUCBC and 78% smaller than with IV HUCBC (p < 0.05). Nevertheless, IM, IA, and IV HUCBC all produced significant reductions in infarct size in comparison with Isolyte-treated infarcted hearts without requirements for host immune suppression. The present experiments demonstrate that the optimal dose of HUCBC for reduction of infarct size in the rat is 4 x 10(6) IM, 4 x 10(6) IA, and 16 x 10(6) IV, and that the IM injection of HUCBC is the most effective technique for reduction in infarct size.