Remus M Berretta's research while affiliated with Temple University and other places

Few therapies have produced significant improvement in cardiac structure and function after ischemic cardiac injury (ICI). Our possible explanation is activation of local inflammatory responses negatively impact the cardiac repair process following ischemic injury. Factors that can alter immune response, including significantly altered cytokine levels in plasma and polarization of macrophages and T cells towards a pro-reparative phenotype in the myocardium post-MI is a valid strategy for reducing infarct size and damage after myocardial injury. Our previous studies showed that cortical bone stem cells (CBSCs) possess reparative effects after ICI. In our current study, we have identified that the beneficial effects of CBSCs appear to be mediated by miRNA in their extracellular vesicles (CBSC-EV). Our studies showed that CBSC-EV treated animals demonstrated reduced scar size, attenuated structural remodeling, and improved cardiac function versus saline treated animals. These effects were linked to the alteration of immune response, with significantly altered cytokine levels in plasma, and polarization of macrophages and T cells towards a pro-reparative phenotype in the myocardium post-MI. Our detailed in vitro studies demonstrated that CBSC-EV are enriched in miR-182/183 that mediates the pro-reparative polarization and metabolic reprogramming in macrophages, including enhanced OXPHOS rate and reduced ROS, via Ras p21 protein activator 1 (RASA1) axis under Lipopolysaccharides (LPS) stimulation. In summary, CBSC-EV deliver unique molecular cargoes, such as enriched miR-182/183, that modulate the immune response after ICI by regulating macrophage polarization and metabolic reprogramming to enhance repair.

Introduction: Pregnancy induces physiological cardiac hypertrophy in healthy women. Our recent findings suggest that obesity can disturb this process and induce pathological cardiac hypertrophy during pregnancy both in human patients and Western Diet (WD) fed mice. Animal studies determined the pathological cardiac hypertrophy is concomitant with increased cardiomyocyte cross-sectional area (CSA), fetal gene activation and fibrosis, however, the underlying mechanisms remain unclear. The present study asks if FoxO1, as a transcriptional factor, may play a role in the adverse cardiac response to pregnancy in WD mice. Methods: The expression levels of FoxO1 and its downstream targeting genes were tested in Ctrl Diet (CD) and WD fed non-pregnant and postpartum animals. To further investigate the role of FoxO1 in pathological cardiac hypertrophy in WD animals during pregnancy, FoxO1 was then silenced by AAV9-shFoxO1 virus in WD mice before breeding. AAV9-scramble RNA served as control. Cardiac phenotype in AAV9 treated WD mice were characterized at post-partum day 1. Results: WD feeding led to increased gene expression levels of FoxO1 and its downstream targeting genes, such as CD36 and PDK4, compared with CD mice. While the gene expression levels of FoxO1 were not different between non-pregnant and pregnant WD mice, FoxO1 protein activation was significantly increased in WD mice after pregnancy determined by a decrease of pFoxO1/tFoxO1 ratio, compared with non-pregnant WD mice. Silencing FoxO1 inhibited the expression levels of FoxO1 and its downstream genes CD36 and PDK4. FoxO1 inhibition in WD fed animals prevented WD induced pathological hypertrophy during pregnancy, with decreased heart weight, cardiomyocyte CSA, attenuated fetal gene activation and fibrosis accumulation. FoxO1 silencing also led to less accumulation of lipid peroxidation product in the myocardium. Conclusions: FoxO1 activation in WD mice with metabolic disturbances during pregnancy can induce pathological cardiac hypertrophy observed during pregnancy.

Objective: Maternal hypothyroidism (MH) could adversely affect the cardiac disease responses of the progeny. This study tested the hypothesis that MH reduces early postnatal cardiomyocyte (CM) proliferation so that the adult heart of MH progeny has a smaller number of larger cardiac myocytes, which imparts adverse cardiac disease responses following injury. Methods and results: Thyroidectomy (TX) was used to establish MH. The progeny from mice that underwent Sham or TX surgery were termed Ctrl (control) or MH (maternal hypothyroidism) progeny, respectively. MH progeny had similar heart weight (HW) to body weight (BW) ratios and larger CM size consistent with fewer CMs at postnatal day 60 (P60) compared with Ctrl progeny. MH progeny had lower numbers of EdU+, Ki67+, and PH3+ CMs, which suggests they had a decreased CM proliferation in the postnatal timeframe. RNA-seq data showed that genes related to DNA replication were downregulated in P5 MH hearts, including bone Morphogenetic Protein 10 (Bmp10). Both in vivo and in vitro studies showed Bmp10 treatment increased CM proliferation. After Transverse Aortic Constriction (TAC), the MH progeny had more severe cardiac pathological remodeling compared with the Ctrl progeny. Thyroid hormone (T4) treatment for MH mothers preserved their progeny's postnatal CM proliferation capacity and prevented excessive pathological remodeling after TAC. Conclusions: Our results suggest that CM proliferation during early postnatal development was significantly reduced in MH progeny, resulting in fewer CMs with hypertrophy in adulthood. These changes were associated with more severe cardiac disease responses after pressure overload.

Background: A recent study suggests that systemic hypoxemia in adult male mice can induce cardiac myocytes to proliferate. The goal of the present experiments was to confirm these results, provide new insights on the mechanisms that induce adult cardiomyocyte cell cycle reentry, and to determine if hypoxemia also induces cardiomyocyte proliferation in female mice. Methods: EdU-containing mini pumps were implanted in 3-month-old, male and female C57BL/6 mice. Mice were placed in a hypoxia chamber, and the oxygen was lowered by 1% every day for 14 days to reach 7% oxygen. The animals remained in 7% oxygen for 2 weeks before terminal studies. Myocyte proliferation was also studied with a mosaic analysis with double markers mouse model. Results: Hypoxia induced cardiac hypertrophy in both left ventricular (LV) and right ventricular (RV) myocytes, with LV myocytes lengthening and RV myocytes widening and lengthening. Hypoxia induced an increase (0.01±0.01% in normoxia to 0.11±0.09% in hypoxia) in the number of EdU+ RV cardiomyocytes, with no effect on LV myocytes in male C57BL/6 mice. Similar results were observed in female mice. Furthermore, in mosaic analysis with double markers mice, hypoxia induced a significant increase in RV myocyte proliferation (0.03±0.03% in normoxia to 0.32±0.15% in hypoxia of RFP+ myocytes), with no significant change in LV myocyte proliferation. RNA sequencing showed upregulation of mitotic cell cycle genes and a downregulation of Cullin genes, which promote the G1 to S phase transition in hypoxic mice. There was significant proliferation of nonmyocytes and mild cardiac fibrosis in hypoxic mice that did not disrupt cardiac function. Male and female mice exhibited similar gene expression following hypoxia. Conclusions: Systemic hypoxia induces a global hypertrophic stress response that was associated with increased RV proliferation, and while LV myocytes did not show increased proliferation, our results minimally confirm previous reports that hypoxia can induce cardiomyocyte cell cycle activity in vivo.

Introduction: Heart failure (HF) with preserved ejection fraction (HFpEF) is defined as HF with an Ejection Fraction (EF) ≥50% and elevated cardiac diastolic filling pressures. The underlying causes of HFpEF are multifactorial and not well-defined. A transgenic mouse with low levels of cardiomyocyte (CM)-specific inducible Cavβ2a expression (β2a-Tg mice) showed increased cytosolic CM Ca2+, and modest levels of CM hypertrophy, and fibrosis. This study aimed to determine if β2a-Tg mice develop a HFpEF phenotype when challenged with two additional stressors, high-fat diet (HFD) and L-NAME (LN). Methods: Four-month-old wild-type (WT) and β2a-Tg mice were given either normal chow (WT-N, β2a-N) or HFD and/or L-NAME (WT-HFD, WT-LN, WT-HFD-LN, β2a-HFD, β2a-LN, and β2a-HFD-LN). Some animals were treated with the HDAC (hypertrophy regulators) inhibitor suberoylanilide hydroxamic acid (SAHA) (β2a-HFD-LN-SAHA). Echocardiography was performed monthly. After four months of treatment, terminal studies were performed including invasive hemodynamics and organs weight measurements. Cardiac tissue was collected. Results: Four months of HFD plus L-NAME treatment did not induce a profound HFpEF phenotype in FVB WT mice. β2a-HFD-LN (3-Hit) mice developed features of HFpEF, including increased natriuretic peptide (ANP) levels, preserved EF, diastolic dysfunction, robust CM hypertrophy, increased M2 macrophage population, and myocardial fibrosis. SAHA reduced the HFpEF phenotype in the 3-Hit mouse model, by attenuating these effects. Conclusions: The 3-Hit mouse model induced a reliable HFpEF phenotype with CM hypertrophy, cardiac fibrosis, and increased M2 macrophage population. This model could be used for identifying and preclinical testing of novel therapeutic strategies.

Introduction: The hemodynamic demands on the heart during normal pregnancy induce physiological cardiac hypertrophy. Together with exercise induced cardiac hypertrophy and cardiac enlargement during post-natal growth, these physiological cardiac adaptations are distinct from pathological hypertrophy caused by heart diseases including volume/pressure overload. Exercise-induced cardiac hypertrophy can induce a protective phenotype that leads to resistance from ischemic injury or pressure overload induced pathological remodeling. Whether pregnancy induced cardiac hypertrophy can also protect the heart from post-partum (PP) pathological stimuli remains unknown and is the focus of this study. Methods: We challenged both post-partum and age matched non-pregnant female C57BL/6 mice with 7-day osmotic minipump infusion of Angiotensin II/phenylephrine (AngII/PE) and determined the cardiac alterations. Results: PP mice had more severe cardiac pathological remodeling after AngII/PE infusion compared with non-pregnant counterparts, with greater increases in heart weight, cardiomyocyte hypertrophy and fibrosis. Echocardiography showed both left and right ventricular hypertrophy without overt systolic dysfunction. PP mice had greater elevations in expression levels of fetal genes and fibrotic genes compared with non-pregnant mice after AngII/PE infusion. RNA-sequencing analysis suggested a more robust change in gene expression level in PP mice after AngII/PE treatment compared to non-pregnant counterparts, with a substantial role for extracellular matrix organization genes. We also found a significant alteration of gene expression levels for enriched extracellular structural organization at 1-day PP, which underlies ongoing structural re-organization in the myocardium shortly after deliver. These PP changes may predispose the heart to adverse remodeling when simultaneously challenged with pathological stimuli. Conclusions: Pregnancy induced cardiac remodeling does not protect the heart against PP pathological stimuli. In fact, the rapid remodeling in the PP heart may predispose it to exacerbation of pathological remodeling.

Introduction: Maternal hypothyroidism (MH) is a common clinical condition with high prevalence. MH is thought to have adverse effects on progeny's cardiac development and disease susceptibility. Hypothesis: MH impacts progeny's postnatal cardiac development and the susceptibility to adverse cardiac disease responses as adults. Methods: MH model was induced by thyroidectomy (TX) with total thyroxine (TT4) under 1ng/dl after surgery. Offspring of mice that underwent TX or Sham surgery was termed THD (Deficient) and THN (Normal) animals. Hearts were collected from THD and THN animals to determine heart weight, cardiomyocyte (CM) size, and CM proliferation. Transverse Aortic Constriction (TAC) was performed to induce pressure overload-induced cardiac hypertrophy and/or heart failure (HF) model in adult THD and THN mice. ECHO (in-vivo) and histological (in-vitro) were performed at specific times after TAC. RNA-seq was performed at embryo day (E) 18.5 and Postnatal day 5 (P5) using heart tissue. Results: The postnatal TT4 level was not different between the THD and THN mice. The heart weight (HW) to body weight (BW) ratio was similar between the two groups on P7, P14, and P60, but the THD mice had larger CM sizes. EdU+, Ki67+, and PH3+ CMs were lower in THD progenies on P0, P5, and P13. RNA-seq data showed that the genes related to cell division and DNA replication were downregulated in THD mice on E18.5 and P5, respectively. In adult animals six weeks after TAC, the THD mice had a greater HW/BW ratio and lung weight(LW) to BW ratio, consistent with more severe cardiac hypertrophy and HF than the THN mice. After TAC, THD mice had a lower LVEF, higher absolute E/e' ratio, greater end-diastolic pressure, and more severe LV fibrosis than THN mice. Conclusions: Alterations in CM proliferation during fetal and early postnatal development results in fewer adult CMs in animals from MH mothers. These changes are associated with increased disease susceptibility in adult MH progeny.

Introduction: Few therapies have produced significant improvement in cardiac function after ischemic cardiac injury (ICI). The activation of local inflammatory responses is critical to cardiac repair after ICI. Our previous studies showed that cortical bone derived stem cells (CBSCs) possess can enhance repair after ICI. Beneficial effects of CBSCs appear to be mediated by paracrine factors including extracellular vesicles (EVs). This study explored if and how these EVs enhance cardiac repair by modulating the ICI immune response. Hypothesis: CBSCs derived extracellular vesicles (CBSC-EV) modulate immune response after ICI. Methods and Results: Both CBSCs and CBSC-EV were transplanted into mice after myocardial infarction (MI). CBSCs and CBSC-EV treated animals had better ICI repair compared with Saline, with reduced scar size, attenuated structural remodeling, improved cardiac function, and reduced cell apoptosis. These effects were linked to alteration of immune response. Plasma analysis of CBSCs and CBSC-EV treated animals showed significantly lower level of pro-inflammatory cytokines such as TNFα 24 hours after MI. CBSCs and CBSC-EV treatment induced significant polarization from CD86+ M1 macrophages towards CD206+ M2 macrophages phenotype 5 days post-MI, with subsequent reduction of CD8+ T cells and increase of CD4+ T cells, especially the FoxP3+ Treg population, from 7 days to 14 days post-MI. RNA sequencing analysis revealed that CBSC-EV contained a distinct transcriptome compared with endothelial progenitor cells and cardiosphere-derived cells. Gene Ontology analysis suggested the differentially expressed genes in CBSC-EV significantly enriched in immune cell receptor binding. MiR-182 and miR-183, which ranked top of the most significantly upregulated genes in CBSC-EV, attenuated M1 macrophage polarization after LPS treatment and promote CD25+ FoxP3+ Treg differentiation in vitro. Conclusions: CBSC-EV enhance cardiac repair by modulating the immune response after injury and highlight the molecular bases of into the beneficial effects of cell-free therapy after ICI.

Approximately 50% of all heart failure (HF) diagnoses can be classified as HF with preserved ejection fraction (HFpEF). HFpEF is more prevalent in females compared to males, but the underlying mechanisms are unknown. We previously showed that pressure overload (PO) in male felines induces a cardiopulmonary phenotype with essential features of human HFpEF. The goal of this study was to determine if slow progressive PO induces distinct cardiopulmonary phenotypes in females and males in the absence of other pathological stressors. Female and male felines underwent aortic constriction (banding) or sham surgery after baseline echocardiography, pulmonary function testing, and blood sampling. These assessments were repeated at 2- and 4-months post-surgery to document the effects of slow progressive pressure overload. At 4-months, invasive hemodynamic studies were also performed. Left ventricle (LV) tissue was collected for histology, myofibril mechanics, extracellular matrix (ECM) mass spectrometry, and single nucleus RNA sequencing (snRNAseq). The induced pressure overload (PO) was not different between sexes. PO also induced comparable changes in LV wall thickness and myocyte cross sectional area in both sexes. Both sexes had preserved ejection fraction, but males had a slightly more robust phenotype in hemodynamic and pulmonary parameters. There was no difference in LV fibrosis and ECM composition between banded male and female animals. LV snRNAseq revealed changes in gene programs of individual cell types unique to males and females after PO. Based on these results, both sexes develop cardiopulmonary dysfunction but the phenotype is somewhat less advanced in females.