Characterization of decellularized left and right ventricular myocardial matrix hydrogels and their effects on cardiac progenitor cells.

Congenital heart defects are the leading cause of right heart failure in pediatric patients. Implantation of c-kit+ cardiac-derived progenitor cells (CPCs) is being clinically evaluated to treat the failing right ventricle (RV), but faces limitations due to reduced transplant cell survival, low engraftment rates, and low retention. These limitations have been exacerbated due to the nature of cell delivery (narrow needles) and the non-optimal recipient microenvironment (reactive oxygen species (ROS)). Extracellular matrix (ECM) hydrogels derived from porcine left ventricular (LV) myocardium have emerged as a potential therapy to treat the ischemic LV and have shown promise as a vehicle to deliver cells to injured myocardium. However, no studies have evaluated the combination of an injectable biomaterial, such as an ECM hydrogel, in combination with cell therapy for treating RV failure. In this study we characterized LV and RV myocardial matrix (MM) hydrogels and performed in vitro evaluations of their potential to enhance CPC delivery, including resistance to forces experienced during injection and exposure to ROS, as well as their potential to enhance angiogenic paracrine signaling. While physical properties of the two hydrogels are similar, the decellularized LV and RV have distinct protein signatures. Both materials were equally effective in protecting CPCs against needle forces and ROS. CPCs encapsulated in either the LV MM or RV MM exhibited similar enhanced potential for angiogenic paracrine signaling when compared to CPCs in collagen. The RV MM without cells, however, likewise improved tube formation, suggesting it should also be evaluated as a potential standalone treatment.

Encapsulation of Pediatric Cardiac-Derived C-Kit+ Cells in Cardiac Extracellular Matrix Hydrogel for Echocardiography-Directed Intramyocardial Injection in Rodents.

Pediatric cardiac-derived c-kit+ cell therapies represent an innovative approach for cardiac tissue repair that have demonstrated promising improvements in recent studies and offer multiple benefits, such as easy isolation and autologous transplant. However, concerns about failure of engraftment and transient paracrine effects have thus far limited their use. To overcome these issues, an appropriate cell delivery vehicle such as a cardiac extracellular matrix (cECM) hydrogel can be utilized. This naturally derived biomaterial can support embedded cells, allowing for local diffusion of paracrine factors, and provide a healthy microenvironment for optimal cellular function. This protocol focuses on combining cardiac-derived c-kit+ cells and a cECM hydrogel to prepare a minimally invasive, dual therapeutic for in vivo delivery. We also outline a detailed method for ultrasound-guided intramyocardial injection of cell-laden hydrogels in a rodent model. Additional steps for labeling cells with a fluorescent dye for in vivo cell tracking are provided.

Using computational methods to design patient-specific electrospun cardiac patches for pediatric heart failure.

Autologous cardiac cell therapy is a promising treatment for combating the right ventricular heart failure (RVHF) that can occur in patients with congenital heart disease (CHD). However, autologous cell therapies suffer from low cell retention following injection and patient-to-patient variability in cell quality. Here, we demonstrate how computational methods can be used to identify mechanisms of cardiac-derived c-Kit+ cell (CPC) reparative capacity and how biomaterials can be designed to improve cardiac patch performance by engaging these mechanisms. Computational modeling revealed the integrin subunit αV (ITGAV) as an important mediator of repair in CPCs with inherently low reparative capacity (CPCslow). We could engage ITGAV on the cell surface and improve reparative capacity by culturing CPCs on electrospun polycaprolactone (PCL) patches coated with fibronectin (PCL + FN). We tested CPCs from 4 different donors and found that only CPCslow with high ITGAV expression (patient 956) had improved anti-fibrotic and pro-angiogenic paracrine secretion on PCL + FN patches. Further, knockdown of ITGAV via siRNA led to loss of this improved paracrine secretion in patient 956 on PCL + FN patches. When implanted in rat model of RVHF, only PCL + FN + 956 patches were able to improve RV function, while PCL +956 patches did not. In total, we demonstrate how cardiac patches can be designed in a patient-specific manner to improve in vitro and in vivo outcomes.