LRP5/canonical Wnt signalling and healing of ischemic myocardium.

LRP5 (low-density lipoprotein receptor-related protein 5) activates canonical Wnt signalling. LRP5 plays multiple roles including regulation of lipoprotein and cholesterol homeostasis as well as innate immunity cell function. However, it is not known whether LRP5 has a role in the myocardium. The aim of this study was to investigate LRP5 and Wnt signalling in myocardial remodelling after acute myocardial infarction (MI). Wnt protein levels were determined in a hypercholesterolemic porcine model of MI, in Lrp5 -/- C57Bl6 mice, in cultured cardiomyocytes and in human explanted hearts with previous MI episodes. 21 days post-MI, there was upregulation of LRP5 in the ischemic myocardium of hypercholesterolemic pigs as well as an upregulated expression of proteins of the Wnt pathway. We demonstrate via overexpression and silencing experiments that LRP5 induces Wnt pathway activation in isolated cardiomyocytes. Hypoxia and lipid-loading induced the expression of Wnt proteins, whereas this effect is blocked in LRP5-silenced cardiomyocytes. To characterize the function of the LRP5-Wnt axis upregulation in the heart, we induced MI in wild-type and Lrp5 -/- mice. Lrp5 -/- mice had significantly larger infarcts than Wt mice, indicating a protective role of LRP5 in injured myocardium. The LRP5 upregulation in post-MI hearts seen in pigs and mice was also evident in human hearts as dyslipidemic patients with previous episodes of ischemia have higher expression of LRP5 and Wnt-signalling genes than non-ischemic dilated hearts. We demonstrate an upregulation of LRP5 and the Wnt signalling pathway that it is a prosurvival healing response of cardiomyocytes upon injury.

Bone Marrow Cell Transplant From Donors With Cardiovascular Risk Factors Increases the Pro-atherosclerotic Phenotype in the Recipients.

Improvement of long-term survival after hematopoietic stem cell transplantation has revealed that these patients have an increased appearance of de novo cardiovascular risk factors. Even though in these clinical studies no relation to transplant-related factors has been found, no attention has been paid to the influence of cardiovascular risk factors affecting the bone marrow donors on the cardiovascular risk of the recipients. Thus, the aim of this study was to analyze, using an animal model, whether transplantation of bone marrow from donors with cardiovascular risk factors increases cardiovascular risk in healthy recipients. Results from transplantation experiments have shown that bone marrow from donors with cardiovascular risk factors induced pro-atherogenic modifications in the cholesterol profile of healthy recipients, increasing the low-density lipoprotein cholesterol fraction in comparison to those transplanted with control bone marrow. Moreover, bone marrow from donors with cardiovascular risk factors induced significant alterations in liver pro-inflammatory state and lipid metabolism-related gene expression that could contribute to alter cholesterol homeostasis. Altogether, these results suggest that cardiovascular risk factors in the donor confer a cardiometabolic alteration to their bone marrow cells that is transferred to noncardiovascular disease transplant recipients, affecting their liver function and increasing their cardiovascular risk.