Recapitulation of the embryonic cardiovascular progenitor cell niche

Department of Cell and Tissue Engineering, Fraunhofer IGB, 70569 Stuttgart, Germany.
Biomaterials (Impact Factor: 8.56). 04/2011; 32(11):2748-56. DOI: 10.1016/j.biomaterials.2010.12.046
Source: PubMed


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 three-dimensionality 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 cardiac niches that can serve as unique 3D in vitro systems to facilitate CPC expansion and study CPC biology.

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Available from: Katja Schenke-Layland
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    • "We have previously demonstrated that ICG-001 reduces the β-catenin/CBP interaction and thereby increases the β-catenin/p300 interaction in a variety of cell types [5], [9]. In contrast, IQ1, a specific small molecule antagonist of the β-catenin/p300 interaction has demonstrated the ability to maintain potency in stem/progenitor cell populations, including cardiovascular progenitors, by increasing the β-catenin/CBP interaction at the expense of the β-catenin/p300 interaction [9], [26]. In the event, we treated rat EMCs, an epicardial mesothelial cell line derived from an adult rat heart explant [27], with either ICG-001 or IQ1 and performed co-immunoprecipitation (co-IP) assays. "
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    ABSTRACT: The adult mammalian heart has limited capability for self-repair after myocardial infarction. Therefore, therapeutic strategies that improve post-infarct cardiac function are critically needed. The small molecule ICG-001 modulates Wnt signaling and increased the expression of genes beneficial for cardiac regeneration in epicardial cells. Lineage tracing experiments, demonstrated the importance of β-catenin/p300 mediated transcription for epicardial progenitor contribution to the myocardium. Female rats given ICG-001 for 10 days post-occlusion significantly improved ejection fraction by 8.4%, compared to controls (P<0.05). Taken together, Wnt modulation via β-catenin/CBP inhibition offers a promising therapeutic strategy towards restoration of myocardial tissues and an enhancement of cardiac functions following infarction.
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    • "As well, Flt1+/Flt4+ CPCs consistently formed beating colonies and CMs in vitro, which appeared to be more fetal in phenotype as seen on immunofluorescence staining (Fig. 4Ad; Figure S2), once transplanted in vivo, they formed CMs with a phenotype and electrophysiological properties typical of adult CMs (Fig. 6). The reason for this discrepancy is unclear, but external cues from the local microenvironment play a critical role in determining cell fate [16] and, a priori, intramyocardial injections would be predicted to favor cardiomyocyte differentiation. The local extracellular matrix along with electromechanical stimulation in vivo may play a role in evolving CMs to a more mature phenotype. "
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    ABSTRACT: Cardiovascular progenitor cells (CPCs) have been identified within the developing mouse heart and differentiating pluripotent stem cells by intracellular transcription factors Nkx2.5 and Islet 1 (Isl1). Study of endogenous and induced pluripotent stem cell (iPSC)-derived CPCs has been limited due to the lack of specific cell surface markers to isolate them and conditions for their in vitro expansion that maintain their multipotency. We sought to identify specific cell surface markers that label endogenous embryonic CPCs and validated these markers in iPSC-derived Isl1(+)/Nkx2.5(+) CPCs. We developed conditions that allow propagation and characterization of endogenous and iPSC-derived Isl1(+)/Nkx2.5(+) CPCs and protocols for their clonal expansion in vitro and transplantation in vivo. Transcriptome analysis of CPCs from differentiating mouse embryonic stem cells identified a panel of surface markers. Comparison of these markers as well as previously described surface markers revealed the combination of Flt1(+)/Flt4(+) best identified and facilitated enrichment for Isl1(+)/Nkx2.5(+) CPCs from embryonic hearts and differentiating iPSCs. Endogenous mouse and iPSC-derived Flt1(+)/Flt4(+) CPCs differentiated into all three cardiovascular lineages in vitro. Flt1(+)/Flt4(+) CPCs transplanted into left ventricles demonstrated robust engraftment and differentiation into mature cardiomyocytes (CMs). The cell surface marker combination of Flt1 and Flt4 specifically identify and enrich for an endogenous and iPSC-derived Isl1(+)/Nkx2.5(+) CPC with trilineage cardiovascular potential in vitro and robust ability for engraftment and differentiation into morphologically and electrophysiologically mature adult CMs in vivo post transplantation into adult hearts.
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    Preview · Article · Apr 2011 · Journal of the American College of Cardiology
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