Sara Rojas-Hernandez

Substantial Early Loss of Induced Pluripotent Stem Cells Following Transplantation in Myocardial Infarction

The limited success of cardiac stem cell therapy has lately generated discussion regarding its effectiveness. We hypothesized that immediate cell loss after intramyocardial injection significantly obscures the regenerative potential of stem cell therapy. Therefore, our aim was to assess the distribution and quantity of induced pluripotent stem cells after intramyocardial delivery using in vivo bioluminescence analysis. In this context, we wanted to investigate if the injection of different cell concentrations would exert influence on cardiac cell retention. Murine-induced pluripotent stem cells were transfected for luciferase reporter gene expression and transplanted into infarcted myocardium in mice after left anterior descending coronary artery ligation. Cells were delivered constantly in aqueous media (15 μL) in different cell concentrations (group A, n = 10, 5.0 × 10(5) cells; group B, n = 10, 1.0 × 10(6) cells). Grafts were detected using bioluminescence imaging. Organ explants were imaged 10 min after injection to quantify early cardiac retention and cell biodistribution. Bioluminescence imaging showed a massive early displacement from the injection site to the pulmonary circulation, leading to lung accumulation. Mean cell counts of explanted organs in group A were 7.51 × 10(4) ± 4.09 × 10(3) (heart), 6.44 × 10(4) ± 2.48 × 10(3) (left lung), and 8.06 × 10(5) ± 3.61 × 10(3) (right lung). Respective cell counts in group B explants were 1.69 × 10(5) ± 7.69 × 10(4) (heart), 2.11 × 10(5) ± 4.58 × 10(3) (left lung), and 3.25 × 10(5) ± 9.35 × 10(3) (right lung). Applying bioluminescence imaging, we could unveil and quantify massive early cardiac stem cell loss and pulmonary cell accumulation following intramyocardial injection. Increased injection concentrations led to much higher intracardiac cell counts; however, pulmonary biodistribution of transplanted cells still persisted. Therefore, we recommend applying tissue engineering techniques for cardiac stem cell transplantations in order to improve cardiac retention and limit biodistribution.

Left Ventricular Assist Device Therapy for Destination Therapy: Is Less Invasive Surgery a Safe Alternative?

INTRODUCTION AND OBJECTIVES The number of older patients with congestive heart failure has dramatically increased. Because of stagnating cardiac transplantation, there is a need for an alternative therapy, which would solve the problem of insufficient donor organ supply. Left ventricular assist devices (LVADs) have recently become more commonly used as destination therapy (DT). Assuming that older patients show a higher risk-profile for LVAD surgery, it is expected that the increasing use of less invasive surgery (LIS) LVAD implantation will improve postoperative outcomes. Thus, this study aimed to assess the outcomes of LIS-LVAD implantation in DT patients. METHODS We performed a prospective analysis of 2-year outcomes in 46 consecutive end-stage heart failure patients older than 60 years, who underwent LVAD implantation (HVAD, HeartWare) for DT in our institution between 2011 and 2013. The patients were divided into 2 groups according to the surgical implantation technique: LIS (n = 20) vs conventional (n = 26). RESULTS There was no statistically significant difference in 2-year survival rates between the 2 groups, but the LIS group showed a tendency to improved patient outcome in 85.0% vs 69.2% (P = .302). Moreover, the incidence of postoperative bleeding was minor in LIS patients (0% in the LIS group vs 26.9% in the conventional surgery group, P < .05), who also showed lower rates of postoperative extended inotropic support (15.0% in the LIS group vs 46.2% in the conventional surgery group, P < .05). CONCLUSIONS Our data indicate that DT patients with LIS-LVAD implantation showed a lower incidence of postoperative bleeding, a reduced need for inotropic support, and a tendency to lower mortality compared with patients treated with the conventional surgical technique.

Multimodal Imaging for In Vivo Evaluation of Induced Pluripotent Stem Cells in a Murine Model of Heart Failure

Myocardial stem cell therapy in heart failure is strongly dependent on successful cellular transfer, engraftment, and survival. Moreover, massive cell loss directly after intramyocardial injection is commonly observed, generating the need for efficient longitudinal monitoring of transplanted cells in order to develop more efficient transplantation techniques. Therefore, the aim of the present study was to assess viability and cardiac retention of induced pluripotent stem cells after intramyocardial delivery using in vivo bioluminescence analysis (BLI) and magnetic resonance imaging (MRI). Murine induced pluripotent stem cells (iPSCs) were transfected for luciferase reporter gene expression and labeled intracellularly with supraparamagnetic iron oxide particles. Consequently, 5 × 105 cells were transplanted intramyocardially following left anterior descending coronary artery ligation in mice. Cardiac iPSCs were detected using BLI and serial T2* sequences by MRI in a 14-day follow-up. Additionally, infarct extension and left ventricular (LV) function were assessed by MRI. Controls received the same surgical procedure without cell injection. MRI sequences showed a strong MRI signal of labeled iPSCs correlating with myocardial late enhancement, demonstrating engraftment in the infarcted area. Mean iPSC volumes were 4.2 ± 0.4 mm3 at Day 0; 3.1 ± 0.4 mm3 at Day 7; and 5.1 ± 0.8 mm3 after 2 weeks. Thoracic BLI radiance decreased directly after injection from 1.0 × 106  ± 4.2 × 104 (p/s/cm2 /sr) to 1.0 × 105  ± 4.9 × 103 (p/s/cm2 /sr) on Day 1. Afterward, BLI radiance increased to 1.1 × 106  ± 4.2 × 104 (p/s/cm2 /sr) 2 weeks after injection. Cardiac graft localization was confirmed by ex vivo BLI analysis and histology. Left ventricular ejection fraction was higher in the iPSC group (30.9 ± 0.9%) compared to infarct controls (24.0 ± 2.1%; P < 0.05). The combination of MRI and BLI assesses stem cell fate in vivo, enabling cardiac graft localization with evaluation of LV function in myocardial infarction.

Prognostic Value of the Nutritional Risk Index in Candidates for Continuous Flow Left Ventricular Assist Device Therapy

INTRODUCTION AND OBJECTIVES Malnutrition has been shown to affect clinical outcomes in patients with heart failure. The aim of this study was to analyze the impact of preoperative nutritional status assessed by the nutritional risk index (NRI) on the prognosis of patients with a continuous-flow left ventricular assist device (cf-LVAD). METHODS We performed a retrospective study of 279 patients who underwent cf-LVAD implantation between 2009 and 2015 in our center. Preoperative NRI was calculated and the patients were followed-up for 1 year. The association between preoperative NRI and postoperative clinical events was analyzed using multivariable logistic regression. RESULTS The prevalence of severe (NRI <83.5), moderate (83.5 ≤ NRI <97.5) and mild (97.5 ≤ NRI <100) nutritional risk was 5.4%, 21.5%, and 9.3%. Mortality rates 1 year after cf-LVAD implantation in these 3 categories were 53.3%, 31.7%, 23.1% vs 18.0% (P <.001) in patients with a normal IRN. A normal preoperative NRI value was an independent predictor of lower risk of death from any cause during follow-up (aHR per 1 unit, 0.961; 95%CI, 0.941-0.981; P <.001) was and a predictor for a lower risk of postoperative infections (aOR, 0.968; 95%CI, 0.946-0.991; P=.007), respiratory failure (aOR, 0,961; 95%CI, 0.936-0.987; P=.004), and right heart failure (aOR, 0.963; 95%CI, 0.934-0.992; P=.014). CONCLUSIONS Malnourished patients are at increased risk for postoperative complications and death after cf-LVAD implantation. Assessment of nutritional risk could improve patient selection and the early initiation of nutritional support.