Adult Cardiac Progenitor Cell Aggregates Exhibit Survival Benefit Both In Vitro and In Vivo

Abstract

BackgroundA major hurdle in the use of exogenous stems cells for therapeutic regeneration of injured myocardium remains the poor survival of implanted cells. To date, the delivery of stem cells into myocardium has largely focused on implantation of cell suspensions.Methodology and Principal FindingsWe hypothesize that delivering progenitor cells in an aggregate form would serve to mimic the endogenous state with proper cell-cell contact, and may aid the survival of implanted cells. Microwell methodologies allow for the culture of homogenous 3D cell aggregates, thereby allowing cell-cell contact. In this study, we find that the culture of cardiac progenitor cells in a 3D cell aggregate augments cell survival and protects against cellular toxins and stressors, including hydrogen peroxide and anoxia/reoxygenation induced cell death. Moreover, using a murine model of cardiac ischemia-reperfusion injury, we find that delivery of cardiac progenitor cells in the form of 3D aggregates improved in vivo survival of implanted cells.ConclusionCollectively, our data support the notion that growth in 3D cellular systems and maintenance of cell-cell contact improves exogenous cell survival following delivery into myocardium. These approaches may serve as a strategy to improve cardiovascular cell-based therapies.

Effective Hypothermic Storage of Human Pluripotent Stem Cell-Derived Cardiomyocytes Compatible With Global Distribution of Cells for Clinical Applications and Toxicology Testing

“…Importantly, our approach for hypothermic storage of 2D monolayers of PSC‐CMs will facilitate the delivery of certified, validated, ready‐to‐use cell plates suitable for high‐throughput cardiac drug testing and toxicity screening, whereas the 1‐week storage strategy for PSC‐CM aggregates will allow the distribution of not only off‐the‐shelf tissue like in vitro models for cardiac toxicity drug testing, but also therapeutic cells that could be directly used in cardiac regenerative therapies. In fact, it has been demonstrated that the delivery of cardiac progenitor cells in the form of 3D cell aggregates improved in vivo survival of implanted cells in a murine model of cardiac injury [64]. The strategies for cold preservation of PSC‐CMs described herein contribute to overcoming the hurdles and needs of the regenerative medicine market and scientific community, constituting a step forward toward improved worldwide commercial distribution of hPSC‐CMs for use in the clinic and biopharmaceutical industry.…”

Engineering Three-Dimensional Stem Cell Morphogenesis for the Development of Tissue Models and Scalable Regenerative Therapeutics

“…91 In the case of single cell suspension, this cellular interaction is completely abrogated by dissociation, whereas it is preserved in the cell aggregates. 8,9,67,72 As previously discussed, cell aggregates also retain endogenous ECM (collagen III, fibronectin and laminin), 29,100 which is transplanted as part of the spheroid microenvironment in vivo and supports cell survival, cell retention and functional enhancement after transplantation. 73 Finally, the composition of cell aggregates may shield the interior cell populations from the damage due to the influence of shear forces upon injection and enable increased retention due to existing cell-cell interactions.…”

“…Cell aggregates can be passed through standard needles without clogging and retain their native spheroid morphology. 9,29 While it has been reported that single cells suspensions exhibit more than 30% acute cell death due to the mechanical disruption caused by extensional flow, the viability of aggregates remained unchanged after passing through a 30G needle. 10 …”

“…155 In contrast, cell aggregation in a scaffold-free format can concentrate cells on the order of 10 6 cells/mm 3 upon aggregation. 9,89,101,140 Additionally, by varying formation conditions, the diameter and cell composition of stem cells aggregates can be highly controlled, 76,89 which enables customization for specific clinical applications.…”

“…Unlike single cell suspensions, which can also be easily injected, enzymatic dissociation is not necessary for cell aggregates, which reduces cell handling and preparation time, and avoids associated decreases in cell viability, 68 ultimately supporting enhanced cell viability and engraftment in vivo . Cell aggregates ranging from 100 to 1000 μm in diameter have been injected intramyocardially, subcutaneously, or intramuscularly to induce myocardial, 9,101 adipose, 29 or bone 140 tissue regeneration, respectively. Cell aggregates can be passed through standard needles without clogging and retain their native spheroid morphology.…”