The cornucopia of "pleiotropic" actions of statins: myogenesis as a new mechanism for statin-induced benefits?

Combined Statin and Glucocorticoid Therapy for the Safer Treatment of Preterm Birth

BACKGROUND

Prematurity is strongly associated with poor respiratory function in the neonate. Rescue therapies include treatment with glucocorticoids due to their anti-inflammatory and maturational effects on the developing lung. However, glucocorticoid treatment in the infant can increase the risk of long-term cardiovascular complications including hypertension, cardiac, and endothelial dysfunction. Accumulating evidence implicates a molecular link between glucocorticoid excess and depletion of nitric oxide (NO) bioavailability as a mechanism underlying the detrimental effects of postnatal steroids on the heart and circulation. Therefore, combined glucocorticoid and statin therapy, by increasing NO bioavailability, may protect the developing cardiovascular system while maintaining beneficial effects on the lung.

METHODS

We investigated combined glucocorticoid and statin therapy using an established rodent model of prematurity and combined experiments of cardiovascular function in vivo, with those in isolated organs as well as measurements at the cellular and molecular levels.

RESULTS

We show that neonatal glucocorticoid treatment increases the risk of later cardiovascular dysfunction in the offspring. Underlying mechanisms include decreased circulating NO bioavailability, sympathetic hyper-reactivity, and NO-dependent endothelial dysfunction. Combined neonatal glucocorticoid and statin therapy protects the developing cardiovascular system by normalizing NO and sympathetic signaling, without affecting pulmonary maturational or anti-inflammatory effects of glucocorticoids.

CONCLUSIONS

Therefore, combined glucocorticoid and statin therapy may be safer than glucocorticoids alone for the treatment of preterm birth.

Osteoporosis Entwined with Cardiovascular Disease: The Implication of Osteoprotegerin and the Example of Statins

Beyond being epiphenomenon of shared epidemiological factors, the integration of Osteoporosis (OP) with Cardiovascular Disease (CVD) - termed "calcification paradox" - reflects a continuum of aberrant cardiometabolic status. The present review provides background knowledge on "calcification paradox", focusing on the endocrine aspect of vasculature orchestrated by the osteoblastic molecular fingerprint of vascular cells, acquired via imbalance among established modulators of mineralization. Osteoprotegerin (OPG), the well-established osteoprotective cytokine, has recently been shown to exert a vessel-modifying role. Prompted by this notion, the present review interrogates OPG as the potential missing link between OP and CVD. However, so far, the confirmation of this hypothesis is hindered by the equivocal role of OPG in CVD, being both proatherosclerotic and antiatherosclerotic. Further research is needed to illuminate whether OPG could be a biomarker of the "calcification paradox". Moreover, the present review brings into prominence the dual role of statins - cardioprotective and osteoprotective - as a potential illustration of the integration of CVD with OP. Considering that the statins-induced modulation of OPG is central to the statins-driven osteoprotective signalling, statins could be suggested as an illustration of the role of OPG in the bone/vessels crosstalk, if further studies consolidate the contribution of OPG to the cardioprotective role of statins. Another outstanding issue that merits further evaluation is the inconsistency of the osteoprotective role of statins. Further understanding of the varying bone-modifying role of statins, likely attributed to the unique profile of different classes of statins defined by distinct physicochemical characteristics, may yield tangible benefits for treating simultaneously OP and CVD.

STATINS AND BONE HEALTH: A MINI REVIEW

Statins are a widely prescribed class of medications that inhibit similar pathways as the anti-resorptive bisphosphonate drugs. Statins target the mevalonate pathway by blocking HMG-CoA reductase. Several recent meta-analyses concluded statins are osteoprotective in the general population. Here we present current literature exploring the mechanisms underlying the putative osteoprotective effects of statins. We also review recent clinical studies, ranging from observational cohort studies to randomized clinical trials, testing the effect of statins on bone health in various populations.

Recruitment and retention of human autologous CD34+ CD117+ CD133+ bone marrow stem cells to infarcted myocardium followed by directed vasculogenesis: Novel strategy for cardiac regeneration

BACKGROUND

Ongoing clinical trials, in regenerative therapy of patients suffering from myocardial infarctions, rely primarily upon administration of bone marrow stem cells to the infarcted zones. Unfortunately, low retention of these cells, to the therapeutic delivery sites, reduces effectiveness of this strategy; thus it has been identified as the most critical problem for advancement of cardiac regenerative medicine.

SPECIFIC AIMS

The specific aim of this work was three-fold: (1) to isolate highly viable populations of human, autologous CD34+, CD117+, and CD133+ bone marrow stem cells; (2) to bioengineer heterospecific, tetravalent antibodies and to use them for recruiting of the stem cells to regenerated zones of infarcted myocardium; (3) to direct vasculogenesis of the retained stem cells with the defined factors.

PATIENTS METHODS

Cardiac tissue was biopsied from the hearts of the patients, who were receiving orthotopic heart transplants after multiple cardiac infarctions. This tissue was used to engineer fully human in vitro models of infarcted myocardium. Bone marrow was acquired from these patients. The marrow cells were sorted into populations of cells displaying CD34, CD117, and CD133. Heterospecific, tetravalent antibodies were bioengineered to bridge CD34, CD117, CD133 displayed on the stem cells with cardiac myosin of the infarcted myocardium. The sorted stem cells were administered to the infarcted myocardium in the in vitro models.

RESULTS

Administration of the bioengineered, heterospecific antibodies preceding administration of the stem cells greatly improved the stem cells' recruitment and retention to the infarcted myocardium. Treatment of the retained stem cells with vascular endothelial growth factor and angiopoietin efficiently directed their differentiation into endothelial cells, which expressed vascular endothelial cadherin, platelet / endothelial cell adhesion molecule, claudin, and occludin, while forming tight and adherens junctions.

CONCLUSIONS

This novel strategy improved retention of the patients' autologous bone marrow stem cells to the infarcted myocardium followed by directed vasculogenesis. Therefore, it is worth pursuing it in support of the ongoing clinical trials of cardiac regenerative therapy.

Simvastatin-enhanced expression of promyogenic nuclear factors and cardiomyogenesis of murine embryonic stem cells

A combination of statin and stem cell therapies has been shown to benefit in experimental models of myocardial infarction. This study tests whether treatment with simvastatin has a direct impact on the cardiomyogenic development of murine embryonic stem cells (ESCs) in embryoid bodies. In a concentration-dependent manner, simvastatin treatment enhanced expression of several promyogenic nuclear transcription factors, including GATA4, Nkx2.5, DTEF-1 and myocardin A. The statin-treated cells also displayed higher levels of cardiac proteins, including myosin, α-actinin, Ryanodine receptor-2, and atrial natriuretic peptide, and they developed synchronized contraction. The statin's promyogenic effect was partially diminished by the addition of the two isoprenoids FPP and GGPP, which are intermediates of cholesterol synthesis. Thus, simvastatin treatment enhances ESC myogenesis during early development perhaps via a mechanism inhibiting the mevalonate-FPP/GGPP pathway.

Recruitment and retention of human autologous CD34+ CD117+ CD133+ bone marrow stem cells to infarcted myocardium followed by directed vasculogenesis: Novel strategy for cardiac regeneration

Background

Ongoing clinical trials, in regenerative therapy of patients suffering from myocardial infarctions, rely primarily upon administration of bone marrow stem cells to the infarcted zones. Unfortunately, low retention of these cells, to the therapeutic delivery sites, reduces effectiveness of this strategy; thus it has been identified as the most critical problem for advancement of cardiac regenerative medicine.

Specific aims

The specific aim of this work was three-fold: (1) to isolate highly viable populations of human, autologous CD34+, CD117+, and CD133+ bone marrow stem cells; (2) to bioengineer heterospecific, tetravalent antibodies and to use them for recruiting of the stem cells to regenerated zones of infarcted myocardium; (3) to direct vasculogenesis of the retained stem cells with the defined factors.

Patients methods

Cardiac tissue was biopsied from the hearts of the patients, who were receiving orthotopic heart transplants after multiple cardiac infarctions. This tissue was used to engineer fully human in vitro models of infarcted myocardium. Bone marrow was acquired from these patients. The marrow cells were sorted into populations of cells displaying CD34, CD117, and CD133. Heterospecific, tetravalent antibodies were bioengineered to bridge CD34, CD117, CD133 displayed on the stem cells with cardiac myosin of the infarcted myocardium. The sorted stem cells were administered to the infarcted myocardium in the in vitro models.

Results

Administration of the bioengineered, heterospecific antibodies preceding administration of the stem cells greatly improved the stem cells’ recruitment and retention to the infarcted myocardium. Treatment of the retained stem cells with vascular endothelial growth factor and angiopoietin efficiently directed their differentiation into endothelial cells, which expressed vascular endothelial cadherin, platelet/endothelial cell adhesion molecule, claudin, and occludin, while forming tight and adherens junctions.

Conclusions

This novel strategy improved retention of the patients’ autologous bone marrow cells to the infarcted myocardium followed by directed vasculogenesis. Therefore, it is worth pursuing it in support of the ongoing clinical trials of cardiac regenerative therapy.

Intracoronary administration of cardiac stem cells in mice: a new, improved technique for cell therapy in murine models

A model of intracoronary stem cell delivery that enables transgenesis/gene targeting would be a powerful tool but is still lacking. To address this gap, we compared intracoronary and intramyocardial delivery of lin(-)/c-kit(+)/GFP(+) cardiac stem cells (CSCs) in a murine model of reperfused myocardial infarction (MI). Lin(-)/c-kit(+)/GFP(+) CSCs were successfully expanded from GFP transgenic hearts and cultured with no detectable phenotypic change for up to ten passages. Intracoronary delivery of CSCs 2 days post-MI resulted in significant alleviation of adverse LV remodeling and dysfunction, which was at least equivalent, if not superior, to that achieved with intramyocardial delivery. Compared with intramyocardial injection, intracoronary infusion was associated with a more homogeneous distribution of CSCs in the infarcted region and a greater increase in viable tissue in this region, suggesting greater formation of new cardiomyocytes. Intracoronary CSC delivery resulted in improved function in the infarcted region, as well as in improved global LV systolic and diastolic function, and in decreased LV dilation and LV expansion index; the magnitude of these effects was similar to that observed after intramyocardial injection. We conclude that, in the murine model of reperfused MI, intracoronary CSC infusion is at least as effective as intramyocardial injection in limiting LV remodeling and improving both regional and global LV function. The intracoronary route appears to be superior in terms of uniformity of cell distribution, myocyte regeneration, and amount of viable tissue in the risk region. To our knowledge, this is the first study to report that intracoronary infusion of stem cells in mice is feasible and effective.