Recapitulation of the embryonic cardiovascular progenitor cell niche

Abstract

Stem or progenitor cell populations are often established in unique niche microenvironments that regulate cell fate decisions. Although niches have been shown to be critical for the normal development of several tissues, their role in the cardiovascular system is poorly understood. In this study, we characterized the cardiovascular progenitor cell (CPC) niche in developing human and mouse hearts, identifying signaling pathways and extracellular matrix (ECM) proteins that are crucial for CPC maintenance and expansion. We demonstrate that collagen IV (ColIV) and β-catenin-dependent signaling are essential for maintaining and expanding undifferentiated CPCs. Since niches are three-dimensional (3D) structures, we investigated the impact of a 3D microenvironment that mimics the in vivo niche ECM. Employing electrospinning technologies, 3D in vitro niche substrates were bioengineered to serve as culture inserts. The threedimensionality of these structures increased mouse embryonic stem cell differentiation into CPCs when compared to 2D control cultures, which was further enhanced by incorporation of ColIV into the substrates. Inhibiting p300-dependent β-catenin signals with the small molecule IQ1 facilitated further expansion of CPCs. Our study represents an innovative approach to bioengineer

Hyaluronan-Based Three-Dimensional Microenvironment Potently Induces Cardiovascular Progenitor Cell Populations

“…Using a live/dead cytotoxicity assay, we can see in Figure 1 that the environment of the hydrogel supports mES cell growth. We did observe a slower proliferation rate (data not shown) of cells encapsulated within the hydrogel as compared to cells maintained on gelatin-(for control) and collagen IV-coated dishes in 2D culture conditions, yet this was similar to the proliferation rates we observed previously when cells were cultured on nanofibrous scaffolds [2,4]. Additionally, we observed different morphologies of cells in 2D culture versus 3D culture.…”

“…We have previously shown that collagen IV in 2D culture conditions induces a greater CPC population and that the addition of an electrospun scaffold further enhances induction of a Flk-1 + CPC population [2,4]. While electrospun scaffolds can be classified as a 3D microenvironment, it can take mES cells up to seven days to migrate to the interior of the scaffold (data not shown).…”

“…These clusters are suggestive of a stem cell niche. Niches are three-dimensional (3D microenvironments that regulate self-renewal, proliferation, and differentiation through cell-cell and cell-matrix interactions [1,2]. It is therefore very important to understand the role of the native extracellular matrix (ECM) that surrounds the CPC niche.…”

“…Previously, we have established that the ECM protein collagen IV induces a greater amount of CPCs than other proteins [2]. Additionally, incorporating a modified 2D substrate, a nanofibrous scaffold, into the culture system further induces a CPC population [4].…”

Myocardial Self-Repair and Congenital Heart Disease

“…Other myocardial niches have been reported. Schenke-Layland (Schenke-Layland et al, 2011) reported that in human and mouse heart endogenous, multipotent Isl1 + /Flk1 + CPC reside within niche clusters in the right ventricular free wall, the atria and outflow tracts. They were tightly circumscribed by the basement membrane proteins collagen V and laminin.…”