Proteins secreted by embryonic stem cells activate cardiomyocytes through ligand binding pathways

Abstract

Human embryonic stem cells (hESC) underly embryogenesis but paracrine signals associated with the process are unknown. This study was designed to 1) profile native proteins secreted by undifferentiated hESC and 2) determine their biological effects on primary neonatal cardiomyocytes. We utilized multi-analyte, immunochemical assays to characterize media conditioned by undifferentiated hESC versus unconditioned media. Expression profiling was performed on cardiomyocytes subjected to these different media conditions and altered transcripts were mapped to critical pathways. Thirty-two of 109 proteins were significantly elevated in conditioned media ranging in concentration from thrombospondin (57.2 ± 5.0 ng/ml) to nerve growth factor (7.4 ± 1.2 pg/ml) and comprising chemokines, cytokines, growth factors, and proteins involved in cell adhesion and extracellular matrix remodeling. Conditioned media induced karyokinesis, cytokinesis and proliferation in mono-and binucleate cardiomyocytes. Pathway analysis revealed comprehensive activation of the ROCK 1 and 2 G-protein coupled receptor (GPCR) pathway associated with cytokinesis, and the RAS/RAF/MEK/ERK receptor tyrosine kinase (RTK) and JAK/STAT-cytokine pathway involved in cell cycle progression. These results provide a partial database of proteins secreted by pluripotent hESC that potentiate cell division in cardiomyocytes via a paracrine mechanism suggesting a potential role for these stem cell factors in cardiogenesis and cardiac repair.

A reduction in ATP demand and mitochondrial activity with neural differentiation of human embryonic stem cells

“…Although no definite exocytotic events were observed, electron micrographs suggest a goblet-cell-like secretion mechanism (Fig. 7C), which is supported by previous results showing the secretion of cytosolic and cytoskeletal proteins in the proteome of hESC-conditioned medium (LaFramboise et al, 2010). By contrast, evidence of autophagy was uncommon, but both lines contained large multivesicular bodies signifying heterophagy.…”

“…As the total energy budget was greater in hESCs than in NSCs, this indicated a faster macromolecule synthesis rate in hESCs; however, in the absence of increased cell division, these extra macromolecules must ultimately be degraded or secreted. hESCs have been shown to secrete a diverse range of chemokines, cytokines, growth factors and matrix remodelling enzymes, along with cytosolic and cytoskeletal components (Bendall et al, 2009;LaFramboise et al, 2010). We found that hESCs had morphological indications of goblet-cell-like secretion and secreted significantly more protein into the extracellular environment than did NSCs.…”

Embryonic stem cells conditioned medium enhances Wharton’s jelly-derived mesenchymal stem cells expansion under hypoxic condition

“…Some of the factors presented in the ESCM such as MIF, PAI-1, sICAM-1, IL-6 and IL-8 have been detected in conditioned medium from undifferentiated human H1/H9 (Bendall et al 2009) and Hsf1 ES cell lines (LaFramboise et al 2010). Interestingly, undifferentiated human H1 and H9 ES cell lines could produce bFGF and TGFb1 which have been identified as growth factor for MSCs proliferation.…”

Rat Induced Pluripotent Stem Cells Protect H9C2 Cells from Cellular Senescence via a Paracrine Mechanism

“…Stem cells whose paracrine effects have been documented include human peripheral blood-derived epithelial stem cells [21], nucleated bone marrow cells [22], skeletal myoblasts [23] and ESCs [6,9], among others. …”

“…Embryonic stem cells (ESCs) are considered to be a more reliable cell source for myocardial regeneration. Besides, recent studies [5,6,7,8,9] found that ESCs could also benefit the heart via a paracrine mechanism. However, the ethical issues associated with embryo manipulation preclude ESCs from clinical application.…”