Objectives To conduct a direct head-to-head comparison of different stem cell types in vitro for various assays of potency, and in vivo for functional myocardial repair in the same mouse model of myocardial infarction. Background Adult stem cells of diverse origins (e.g., bone marrow, fat, heart) and antigenic identity have been studied for repair of the damaged heart, but the relative utility of the various cell types remains unclear. Methods Human cardiosphere-derived stem cells (CDCs), bone marrow-derived mesenchymal stem cells (BM-MSCs), adipose tissue-derived mesenchymal stem cells (AD-MSCs), and bone marrow mononuclear cells (BM-MNCs) were compared. Results CDCs revealed a distinctive phenotype with uniform expression of CD105, partial expression of c-kit and CD90, and negligible expression of hematopoietic markers. In vitro, CDCs showed the greatest myogenic differentiation potency, highest angiogenic potential, and relatively high production of various angiogenic and anti-apoptotic secreted factors. In vivo, injection of CDCs into the infarcted mouse hearts resulted in superior improvement of cardiac function, the highest cell engraftment and myogenic differentiation rates, and the least-abnormal heart morphology 3 weeks after treatment. CDC-treated hearts also exhibited the lowest number of apoptotic cells. The c-kit+ subpopulation purified from CDCs produced lower levels of paracrine factors and inferior functional benefit when compared to unsorted CDCs. To validate the comparison of cells from various human donors, selected results were confirmed in cells of different types derived from individual rats. Conclusions CDCs exhibit a balanced profile of paracrine factor production, and, among various comparator cell types/subpopulations, provide the greatest functional benefit in experimental myocardial infarction.

Background Magnetic Resonance Imaging (MRI) in the CADUCEUS trial revealed that cardiosphere-derived cells (CDCs) decrease scar size and increase viable myocardium post-myocardial infarction (MI), but MRI has not been validated as an index of regeneration after cell therapy. We tested the validity of contrast-enhanced MRI in quantifying scarred and viable myocardium after cell therapy in a porcine model of convalescent MI. Methods and Results Yucatan minipigs underwent induction of MI and 2-3 weeks later were randomized to receive intracoronary infusion of 12.5×106 mismatched allogeneic CDCs or vehicle. Allogeneic CDCs induced mild local mononuclear infiltration but no systemic immunogenicity. MRI revealed that allogeneic CDCs attenuated remodeling, improved global and regional function, decreased scar size and increased viable myocardium compared to placebo 2 months post-treatment. Extensive histological analysis validated quantitatively the MRI measurements of scar size, scar mass and viable mass. CDCs neither altered gadolinium contrast myocardial kinetics, nor induced changes in vascular density or architecture in viable and scarred myocardium. Histology demonstrated that CDCs lead to cardiomyocyte hyperplasia in the border zone, consistent with the observed stimulation of endogenous regenerative mechanisms (cardiomyocyte cycling, upregulation of endogenous progenitors, angiogenesis). Conclusions Contrast-enhanced MRI accurately measures scarred and viable myocardium after cell therapy in a porcine model of convalescent MI. MRI represents a useful tool for assessing dynamic changes in the infarct and monitoring regenerative efficacy.

Objectives This study sought to compare the regenerative potency of cells derived from healthy and diseased human hearts. Background Results from pre-clinical studies and the CADUCEUS (CArdiosphere-Derived aUtologous stem CElls to reverse ventricUlar dySfunction) trial support the notion that cardiosphere-derived cells (CDCs) from normal and recently infarcted hearts are capable of regenerating healthy heart tissue after myocardial infarction (MI). It is unknown whether CDCs derived from advanced heart failure (HF) patients retain the same regenerative potency. Methods In a mouse model of acute MI, we compared the regenerative potential and functional benefits of CDCs derived from 3 groups: 1) non-failing (NF) donor: healthy donor hearts post-transplantation; 2) MI: patients who had an MI 9 to 35 days before biopsy; and 3) HF: advanced cardiomyopathy tissue explanted at cardiac transplantation. Results Cell growth and phenotype were identical in all 3 groups. Injection of HF CDCs led to the greatest therapeutic benefit in mice, with the highest left ventricular ejection fraction, thickest infarct wall, most viable tissue, and least scar 3 weeks after treatment. In vitro assays revealed that HF CDCs secreted higher levels of stromal cell-derived factor 1 (SDF-1), which may contribute to the cells’ augmented resistance to oxidative stress, enhanced angiogenesis, and improved myocyte survival. Histological analysis indicated that HF CDCs engrafted better, recruited more endogenous stem cells, and induced greater angiogenesis and cardiomyocyte cell-cycle re-entry. CDC-secreted SDF-1 levels correlated with decreases in scar mass over time in CADUCEUS patients treated with autologous CDCs. Conclusions CDCs from advanced HF patients exhibit augmented potency in ameliorating ventricular dysfunction post-MI, possibly through SDF-1–mediated mechanisms.

NIRF-labeled integrin antagonists allow noninvasive molecular fluorescent imaging and quantification of tumors in vivo, improving and providing more refined approaches for cancer detection and treatment monitoring.

The vast majority of cells delivered into the heart by conventional means are lost within the first 24 hours. Methods are needed to enhance cell retention, so as to minimize loss of precious material and maximize effectiveness of the therapy. We tested a cell-hydrogel delivery strategy. Cardiosphere-derived cells (CDCs) were grown from adult human cardiac biopsy specimens. In situ polymerizable hydrogels made of hyaluronan and porcine gelatin (Hystem®-C™) were formulated as a liquid at room temperature so as to gel within 20 minutes at 37°C. CDC viability and migration were not compromised in Hystem-C™. Myocardial infarction was created in SCID mice and CDCs were injected intramyocardially in the infarct border zone. Real time PCR revealed engraftment of CDCs delivered in Hystem-C™ was increased by nearly an order of magnitude. LVEF (left ventricular ejection fraction) deteriorated in the control (PBS only) group over the 3-week time course. Hystem-C™ alone or CDCs alone preserved LVEF relative to baseline, while CDCs delivered in Hystem-C™ resulted in a sizable boost in LVEF. Heart morphometry revealed the greatest attenuation of LV remodeling in the CDC + Hystem-C™ group. Histological analysis suggested cardiovascular differentiation of the CDCs in Hystem-C™. However, the majority of functional benefit is likely from paracrine mechanisms such as tissue preservation and neovascularization. A CDC/hydrogel formulation suitable for catheter-based intramyocardial injection exhibits superior engraftment and functional benefits relative to naked CDCs.