Citations

Introduction: The process of engaging stem cells towards a cardiopoietic (CP) state was established using a protein-based cocktail consisting of multiple growth factors. Although this regenerative enhancement protocol has been successfully tested in advanced clinical trials, it remains resource-intensive. Recent efforts have focused on streamlining cardiopoiesis through a protein-independent alternative that leverages a transfection-based mRNA approach. Microencapsulated modified messenger RNA (M3RNA) was utilized to deliver brachyury (T), an early mesodermal transcription factor to provoke early lineage specification in pluripotent cells. Hypothesis: Transfection of a human pluripotent stem cell source with T induces early expression of CP transcription factors to accelerate cardiac differentiation. Methods: Human pluripotent stem cells were transfected with T and maintained for 14 days. Expression of the cardiopoietic markers MEF2C, GATA4, and Nkx2.5 was analyzed using RT-qPCR, in tandem with MYH6 at days 10 and 20. Differentiation proficiency was independently corroborated by assessing Mef2c and Nkx2.5 expression by IF. Results: Following transfection with T, Nkx2.5, MEF2C and GATA4 were significantly induced at 72h (60-, 20- and 40-fold, respectively, p<0.01 for all 3 markers vs baseline), reflecting timing of differentiation initiation. At 5 days post differentiation, expression of the cardiac-specific Nkx2.5 increased by 5 fold vs control and the cell cycle regulator CHIR (p<0.01), suggesting successful persistent induction of cardiopoeisis. At 10 and 20 days of differentiation, RNA expression of MYH6 was 10-15 times induced in human pluripotent cells transduced with T (p < 0.0001, and p < 0.001 vs control, respectively), compared to 2 times (p<0.05, p<0.01 vs control, respectively) in CHIR treated cohorts. Accordingly, at 42 days post-induction of differentiation, a greater number of cells expressed MLC2V and cTnT (p<1e-05, <1e-07, respectively vs control), driving a robust beating pattern. Conclusion: This study implements a single gene T M3RNA-based approach to readily induce cardiac differentiation from pluripotent sources, exceeding available commercial platforms.

Introduction: We aim to elucidate the incidence of major complications related to right heart catheterization (RHC) and ascertain if there are unique risks with right ventricular biopsy. Methods: Diagnostic RHC procedures from 1/1/2002 through 12/31/2013 were identified using the clinical scheduling system at Mayo Clinic, Rochester. Major complications were identified through electronic records using International Classification of Diseases, Ninth Revision billing codes. All events were recorded and adjudicated. Analysis was performed on four separate patient categories (RHC/RV angiography alone, RV biopsy alone, multiple RHC procedures, and concurrent RHC/LHC procedures) and the overall group. Primary outcomes are described in Table 1. Outcomes were measured within 7 days of the procedure, except for death (same day events) and tricuspid regurgitation (variable time endpoints). Results: There were 17,696 RHC procedures (5,556 RHC/RV angiography, 3,846 RV biopsy alone, 776 multiple RHC procedures, and 7,518 combined RHC/LHC). Patient population had a mean age of 56.5 years (15.3) and was predominantly male (58.5%). Same-day death related to RHC procedure occurred in 1 procedure or 0.6 of 10,000 RHCs. There was no significant difference in the risk of complications across RHC procedure categories except for worsening tricuspid regurgitation, which was significantly (p<0.001) more prevalent with RV biopsy (392 cases, 6.0%) than without (136 cases, 1.2%). Conclusion: The incidence of major complications related to right heart catheterization is rare. Worsening tricuspid regurgitation is the most frequently identified change with a significantly higher prevalence with biopsies.

Introduction: Baseline hemodynamic parameters have been shown to predict postoperative outcomes such as right ventricular failure (RVF) in LVAD patients. The pressure adjusted heart rate (PaHR) is a hemodynamic parameter that has not been reported in LVAD recipients. Hypothesis: Patients with an elevated PaHR at baseline will have an increased risk of adverse outcomes following LVAD implantation. Methods: Historical cohort study of 273 patients with preoperative invasive hemodynamic assessment before durable LVAD implantation from January 1 st , 2007 to April 10 th 2017. Baseline patient characteristics and hemodynamic parameters were assessed. The primary endpoint was a composite of 30 day mortality, stage 3 acute kidney injury (AKI), and postoperative RVF. Univariate analysis was used to identify predictors of the composite endpoint, which were entered into stepwise backwards multivariate logistic regression to determine independent predictors of the composite outcome. Results: The mean age was 59 and 79% of the patients were male. The median INTERMACS profile was 4 and 166 (60%) of LVADs placed were as destination therapy. The primary composite endpoint was reached by 74 (27%) patient, including 30-day mortality in 13 (5%), severe AKI in 48 (18%) and RVF in 53 (19%). Univariate predictors of the composite endpoint (p <0.05) included atrial fibrillation, INTERMACS profile, home inotropes, preoperative IABP, admission creatinine, baseline Vasoactive-Inotropic Score, mean right atrial pressure (mRAP), mRAP/wedge, mean arterial pressure/mRAP, mean pulmonary artery pressure/mRAP, right ventricular stroke work index (RVSWi), pulmonary artery pulsatility index, and the PaHR. Logistic regression identified PaHR (OR 0.96, 95% CI 0.93-0.99, p=.026), RVSWi (OR 1.002, 95% CI 1.001-1.004, p=.002), home inotropes (OR 0.46, 95% CI 0.22-0.94, p=.034), atrial fibrillation (OR 0.48, 95% CI 0.26-0.88, p=.019) and admission creatinine (OR 0.51, 95% CI 0.34-0.77, p=0.002) as predictors of the composite endpoint. Conclusions: The PaHR is a readily available, novel hemodynamic parameter, that when elevated on baseline hemodynamic assessment can predict those patients at increased risk of postoperative adverse outcomes after durable LVAD implantation.

Introduction: Patients at increased risk of complications following LVAD placement are admitted to the hospital for hemodynamic optimization prior to LVAD implantation, which can include adjustment of medical therapy and/or placement of an IABP. Hypothesis: Prior to LVAD placement patients treated with an IABP during hemodynamic optimization will have similar outcomes despite worse baseline characteristics compared with patients treated medically. Methods: This single-center study included 199 non-inotrope dependent patients who underwent durable LVAD implantation between January 1 st , 2007 and April 10 th 2017. Hemodynamic data was collected retrospectively. Patients who received an IABP were compared to those who did not. Stage 2 or 3 acute kidney injury, right ventricular failure, and 30 day mortality was compared between patients with and without and IABP. Results: The mean age was 62.7 and 82.9% were male; 72 (36.2%) received an IABP. Baseline characteristics between groups were similar. Patients treated with an IABP had worse INTERMACS profiles and worse baseline hemodynamic parameters. The incidence of the primary composite endpoint was similar between patients who had an IABP and those who did not (23.6% vs 19.7%; p=0.517), as were each of the individual endpoints: stage 2 or 3 acute kidney injury (18.1% vs 14.2%; p=0.472), right ventricular failure (13.9% vs 13.4%; p=0.796), and 30 day mortality (6.9 % vs 3.2%; p=0.226). Patients treated with an IABP had greater relative reductions in mean right atrial pressure (-24.1% vs -5.9%; p=0.044), pulmonary artery systolic (-11.7% vs +3.3%; p=<0.001), diastolic (-17.0% vs +12.0%; p=0.015), and mean pressures (-15.2% vs 0.5%; p=<0.001). Conclusions: Despite worse hemodynamic parameters and INTERMACS profile at baseline, ambulatory heart failure patients who received an IABP prior to LVAD implantation did not have an increased incident of stage 2 or 3 acute kidney injury, right ventricular failure, or 30 day mortality, and had more favorable reductions in right atrial and pulmonary artery pressures. These results suggest that the use of the IABP prior to LVAD implantation in non-inotrope dependent patients with poor baseline hemodynamics may mitigate the risk of postoperative complications.

AbstractRamp studies are utilized for speed optimization of continuous flow left ventricular assist devices (CF‐LVADs). We here report the utility of combined left and right heart catheterization during a ramp study to ensure a comprehensive understanding of the hemodynamic implications on both ventricles. Pressure‐volume loop (PV loop) monitoring uncovered compromised systolic and mildly compromised right ventricular function with increasing LVAD speeds, despite improvement in left ventricular unloading. These findings informed patient management and highlight the potential utility of PV loop monitoring as an adjunct to left and right heart catheterization during ramp studies of next‐generation LVADs.

The purpose of this study was to evaluate the biodistribution of a platelet-derived exosome product (PEP), previously shown to promote regeneration in the setting of wound healing, in a porcine model delivered through various approaches. Exosomes were labeled with DiR far-red lipophilic dye to track and quantify exosomes in tissue, following delivery via intravenous, pulmonary artery balloon catheter, or nebulization in sus scrofa domestic pigs. Following euthanasia, far-red dye was detected by Xenogen IVUS imaging, while exosomal protein CD63 was detected by Western blot and immunohistochemistry. Nebulization and intravenous delivery both resulted in global uptake of exosomes within the lung parenchyma. However, nebulization resulted in the greatest degree of exosome uptake. Pulmonary artery balloon catheter-guided delivery provided the further ability to localize pulmonary delivery. No off-target absorption was noted in the heart, spleen, or kidney. However, the liver demonstrated uptake primarily in nebulization-treated animals. Nebulization also resulted in uptake in the trachea, without significant absorption in the esophagus. Overall, this study demonstrated the feasibility of pulmonary delivery of exosomes using nebulization or intravenous infusion to accomplish global delivery or pulmonary artery balloon catheter-guided delivery for localized delivery.

The purpose of this study was to evaluate left ventricular (LV) unloading strategies in patients supported with peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO). A retrospective review was conducted of all consecutive patients requiring VA-ECMO support for any indication, who underwent novel LV unloading strategies with either direct left atrial venoarterial (LAVA) cannulation or pulmonary artery venoarterial (PAVA) venting, in comparison to Impella and intra-aortic balloon pump (IABP). The primary outcome was successful bridge to transplant, LV assist device, or myocardial recovery. Forty-six patients (63% male, mean age 52.8 ± 17.6 years) were included. Fourteen patients (30%) underwent novel unloading with either LAVA or PAVA, 11 patients (24%) underwent IABP placement, and 21 patients (46%) underwent Impella insertion. In the novel LV unloading cohort, 10 patients (71%) survived to hospital discharge. Four patients (29%) were weaned from ECMO and eight patients (57%) underwent cardiac transplantation. Although a trend favoring cannula-based unloading for the primary outcome was noted, the cohort was too small for statistical significance (79% LAVA/PAVA, 57% Impella, 45% IABP; p = 0.21). However, probability of survival was greater in the LAVA/PAVA cohort compared to Impella and IABP (p < 0.05). Thus, we demonstrate the efficacy of LA and PA cannulation as an alternative LV unloading strategy for patients supported with peripheral VA-ECMO.

AbstractBackgroundGastrointestinal bleeding (GIB) in patients with continuous flow left ventricular assist devices (CF‐LVADs) is often related to GI angiodysplasia (GIAD). We previously reported data on VEGF inhibition with IV bevacizumab in the treatment of LVAD‐associated GIAD bleeding, and now present follow‐up data on patients treated with IV bevacizumab and/or low‐dose oral pazopanib.MethodsAll consecutive adult patients with LVAD‐associated GIB from GIAD treated with bevacizumab or pazopanib, from July 20, 2017 to June 22, 2022, were included in the analysis. Data on hospitalizations, GI endoscopic procedures, and blood transfusions were obtained from first admission for GIB up to a median of 35.7 months following treatment initiation (range 1.3–59.8 months).ResultsEleven patients (91% male, mean 69.5 ± 8.9 years) were included. Eight patients (73%) received IV bevacizumab, two patients (18%) received oral pazopanib, and one patient (9%) received bevacizumab followed by pazopanib therapy. We observed a significantly decreased number of annualized hospitalizations for GIB (median difference − 2.87, p = 0.002), blood transfusions (median difference − 20.9, p = 0.01), and endoscopies (median difference − 6.95, p = 0.007) in patients pre‐ and post‐anti‐angiogenic therapy (bevacizumab and/or pazopanib). Similarly, a significant improvement in these clinical outcomes was noted in the bevacizumab group with decreased annualized hospitalizations (median difference − 2.75, p = 0.014), blood transfusions (median difference − 24.5, p = 0.047), and number of endoscopies (median differences −6.88, p = 0.006).ConclusionAnti‐angiogenic therapy with IV bevacizumab and/or low‐dose oral pazopanib appears to provide benefits in patients with LVAD‐associated GIB with reduced hospitalizations, blood transfusions, and need for GI endoscopic procedures.

Introduction: Platelets are heavily implicated in angiogenesis; however, the underlying mechanism remains relatively uncharacterized. The goal of this study was to evaluate the angiogenic potency of a platelet-derived regenerative exosome product (PEP) in an effort to develop a novel treatment for peripheral arterial disease. Here, we evaluated the mechanistic basis of PEP in angiogenesis and it’s use In Vivo in a rodent hind limb ischemia model. Methods/Results: Under Current Good Manufacturing Practices, conditioned medium from apheresis platelet cultures was purified to acquire the exosomes. PEP, enriched in exosome markers CD63, CD9 and Flotillin, induced human umbilical vein endothelial cell (HUVEC) proliferation, migration, and vascular tube formation In Vitro. Proteomic evaluation of PEP highlighted receptor tyrosine kinase (RTK) pathways and western blot validation demonstrated induction of phospho-MAPK and phospho-AKT following PEP treatment of HUVECs. Systematic evaluation of RTK receptor involvement was performed using small molecule inhibitors and receptor knock-down in HUVECs, ruling out RTK activation as a mode of action. However, small molecule inhibition of PI3 kinase demonstrated elimination of PEP-induced AKT phosphorylation and reduction in PEP-induced angiogenesis In Vitro measured by HUVEC proliferation and migration. In Vivo, evaluation of angiogenesis was performed in a rodent model of hindlimb ischemia treated with PEP embedded in fibrin glue (PEP/TISSEEL). Blood flow was evaluated by SPY angiography on day 0 pre- and post-operation, day 21, and day 28. Animals treated with PEP/TISSEEL showed a significant increase in blood flow compared to sham and TISSEEL treated animals (percent perfusion at 28 days: sham 40.9%, TISSEEL 44.3%, PEP/TISSEEL 100.2%), with significant increase in vascular area on histology (at 28 days vascular area (μm 2 )/muscle area(μm 2 ): healthy control 12.71, sham 4.66, TISSEEL 4.76, PEP/TISSEEL 15.54). Conclusions: Exosome driven activation of PI3 kinase can induce angiogenesis both In Vitro and In Vivo. PEP provides a novel, clinical-grade, off-the-shelf therapy to promote angiogenesis for the treatment of peripheral arterial disease.

Introduction: Patients with coronary artery disease (CAD) not amenable to revascularization are reported to have a 3-year mortality >14%. Advances in treatment modalities including medical management, rotational atherectomy, balloon lithotripsy, and drug-eluting stents work for focal disease but poorly treat diffuse CAD. In a porcine model of in-stent restenosis, we here evaluated whether a pro-angiogenic platelet-derived exosome product (PEP) could be delivered into the perivascular space to foster collateral vessel formation. Methods/Results: Cobalt chromium stents were placed and were oversized by 1 mm in the left anterior descending (LAD) and posterior descending arteries (PDA) of sus scrofa domesticus pigs. In-stent restenosis was angiographically visualized at the 2-month timepoint, with hemodynamic significance documented with fractional flow reserve (FFR) of <0.8. To document feasibility of PEP delivery into the perivascular space, exosomes were labeled with a far-red fluorescent tag and delivered into the perivascular bed. Here, the Bullfrog® micro-infusion catheter was positioned either in the great cardiac vein or the middle cardiac vein and PEP was delivered with the microneedle pointed towards the LAD or the PDA. Biodistribution demonstrated exosome retention and uptake around cardiac veins. Using the Bullfrog® technique, PEP was delivered in the perivascular space adjacent to areas of significant coronary stenosis. Initial results 1-month post-treatment demonstrated improved FFR of treated stenotic vessels (from 0.68 to 0.85), while untreated vessels demonstrate no change from previous FFR measurement (from 0.79 to 0.78). Conclusions: Here, exosome-mediated angiogenesis in the perivascular space improved coronary blood flow, distal to areas of stenosis. In patients with diffuse CAD, delivery of biotherapy in cardiac veins running anatomically parallel to stenosed epicardial arteries provides a novel therapeutic opportunity to supplement the existing armamentarium of therapies available for in-stent restenosis.