The complex biology of KIT+ cells in the heart

Human-derived decellularized extracellular matrix scaffold incorporating autologous bone marrow stem cells from patients with congenital heart disease for cardiac tissue engineering

BACKGROUND

Stem cells are used as an alternative treatment option for patients with congenital heart disease (CHD) due to their regenerative potential, but they are subject to low retention rate in the injured myocardium. Also, the diseased microenvironment in the injured myocardium may not provide healthy cues for optimal stem cell function.

OBJECTIVE

In this study, we prepared a novel human-derived cardiac scaffold to improve the functional behaviors of stem cells.

METHODS

Decellularized extracellular matrix (ECM) scaffolds were fabricated by removing cells of human-derived cardiac appendage tissues. Then, bone marrow c-kit+ progenitor cells from patients with congenital heart disease were seeded on the cardiac ECM scaffolds. Cell adhesion, survival, proliferation and cardiac differentiation on human cardiac decellularized ECM scaffold were evaluated in vitro. Label-free mass spectrometry was applied to analyze cardiac ECM proteins regulating cell behaviors.

RESULTS

It was shown that cardiac ECM scaffolds promoted stem cell adhesion and proliferation. Importantly, bone marrow c-kit+ progenitor cells cultured on cardiac ECM scaffold for 14 days differentiated into cardiomyocyte-like cells without supplement with any inducible factors, as confirmed by the increased protein level of Gata4 and upregulated gene levels of Gata4, Nkx2.5, and cTnT. Proteomic analysis showed the proteins in cardiac ECM functioned in multiple biological activities, including regulation of cell proliferation, regulation of cell differentiation, and cardiovascular system development.

CONCLUSION

The human-derived cardiac scaffold constructed in this study may help repair the damaged myocardium and hold great potential for tissue engineering application in pediatric patients with CHD.

Cardiac regenerative therapy: Many paths to repair

Cardiovascular disease remains the primary cause of death in the United States and in most nations worldwide, despite ongoing intensive efforts to promote cardiac health and treat heart failure. Replacing damaged myocardium represents perhaps the most promising treatment strategy, but also the most challenging given that the adult mammalian heart is notoriously resistant to endogenous repair. Cardiac regeneration following pathologic challenge would require proliferation of surviving tissue, expansion and differentiation of resident progenitors, or transdifferentiation of exogenously applied progenitor cells into functioning myocardium. Adult cardiomyocyte proliferation has been the focus of investigation for decades, recently enjoying a renaissance of interest as a therapeutic strategy for reversing cardiomyocyte loss due in large part to ongoing controversies and frustrations with myocardial cell therapy outcomes. The promise of cardiac cell therapy originated with reports of resident adult cardiac stem cells that could be isolated, expanded and reintroduced into damaged myocardium, producing beneficial effects in preclinical animal models. Despite modest functional improvements, Phase I clinical trials using autologous cardiac derived cells have proven safe and effective, setting the stage for an ongoing multi-center Phase II trial combining autologous cardiac stem cell types to enhance beneficial effects. This overview will examine the history of these two approaches for promoting cardiac repair and attempt to provide context for current and future directions in cardiac regenerative research.

Cardiac ageing: extrinsic and intrinsic factors in cellular renewal and senescence

Cardiac ageing manifests as a decline in function leading to heart failure. At the cellular level, ageing entails decreased replicative capacity and dysregulation of cellular processes in myocardial and nonmyocyte cells. Various extrinsic parameters, such as lifestyle and environment, integrate important signalling pathways, such as those involving inflammation and oxidative stress, with intrinsic molecular mechanisms underlying resistance versus progression to cellular senescence. Mitigation of cardiac functional decline in an ageing organism requires the activation of enhanced maintenance and reparative capacity, thereby overcoming inherent endogenous limitations to retaining a youthful phenotype. Deciphering the molecular mechanisms underlying dysregulation of cellular function and renewal reveals potential interventional targets to attenuate degenerative processes at the cellular and systemic levels to improve quality of life for our ageing population. In this Review, we discuss the roles of extrinsic and intrinsic factors in cardiac ageing. Animal models of cardiac ageing are summarized, followed by an overview of the current and possible future treatments to mitigate the deleterious effects of cardiac ageing.