Leukemia Inhibitory Factor Modulates Cardiogenesis in Embryoid Bodies in Opposite Fashions

Abstract

Cardiogenesis is a multistep process regulated by a hierarchy of factors defining each developmental stage of the heart. One of these factors, leukemia inhibitory factor (LIF), a member of the interleukin-6 family of cytokines, is expressed in embryonic and neonatal cardiomyocytes and induces cardiomyocyte hypertrophy. Many aspects of embryogenesis are faithfully recapitulated during in vitro differentiation of embryonic stem cells in embryoid bodies. We exploited this model to study effects of growth factors on commitment and differentiation of cardiomyocytes and on maintenance of their phenotype. We identified LIF as a factor affecting commitment and differentiation of cardiomyocytes in an opposite manner. Diffusible LIF inhibited mesoderm formation and hampered commitment of cardiomyocytes. Lack of both the diffusible and matrix-bound isoforms of LIF in lif-/- embryoid bodies did not interfere with commitment, but it severely suppressed early differentiation of cardiomyocytes. Onset of differentiation was rescued by very low concentrations of diffusible LIF; however, consecutive differentiation was attenuated in a concentration-dependent manner by diffusible LIF both in wild-type and lif-/- cardiomyocytes. Differentiation of cardiomyocytes was severely hampered but not completely blocked in lifr-/- embryoid bodies, suggesting additional, LIF-receptor ligand independent pathways for commitment and differentiation of cardiomyocytes. At the fully differentiated state, both paracrine and autocrine LIF promoted proliferation and increased longevity of cardiomyocytes. These findings suggest that both paracrine and autocrine and both diffusible and matrix-bound isoforms of LIF contribute to the modulation of cardiogenesis in a subtle, opposite, and developmental stage-dependent manner and control proliferation and maintenance of the differentiated state of cardiomyocytes.

Differentiation of Pluripotent Embryonic Stem Cells Into Cardiomyocytes

“…On the basis of the in vitro differentiation model with targeted cells, LIF has been found to affect commitment and differentiation of cardiomyocytes in a conflicting manner. 37 In developing EBs between days 0 to 4, the presence of diffusible LIF inhibits mesoderm formation and commitment of cardiomyocytes. Differentiation of cardiomyocytes, but not commitment, is also severely hampered by the absence of LIF.…”

Embryonic stem cells and cardiomyocyte differentiation: phenotypic and molecular analyses

“…It also indirectly influences cardiomyogenesis in mES cell cultures through its effects on parietal endoderm differentiation [47,48]. By altering in the forming EB the relative content of other cell lineages (e.g., endoderm) that provided cardiomyogenic-inducing factors, the differentiation potential of ES cells to form CMs will be adversely affected.…”

Cardiac Repair by Embryonic Stem-Derived Cells

“…Perhaps not unexpectedly, cytokine/growth factor treatments were occasionally observed to promote cardiomyogenic differentiation via rather indirect mechanisms. For example, LIF (leukemia inhibitory factor) regulated cardiomyogenesis in ES cultures indirectly via its effect on parietal endoderm differentiation (Bader et al 2000;Bader et al 2001). Thus, altering the relative content of other cell lineages that subsequently provided cardiomyogenic-inducing factors enhanced the yield of cardiomyocytes.…”