posted on 2013-11-08, 00:00authored byRobert A. Boomsma, David L. Geenen
We have previously shown that mesenchymal stem cells (MSC) improve function upon integration in ischemic myocardium.
We examined whether specific cytokines and growth factors produced by MSCs are able to affect angiogenesis, cellular
migration and apoptosis. Conditioned media (CM) was prepared by culturing MSC for 48 hours. CM displayed significantly
elevated levels of VEGF, Monocyte Chemoattractant Protein-1 (MCP-1), macrophage inflammatory protein-1a (MIP-1a), MIP-
1b and monokine induced by IFN-c (MIG) compared to control media. MSC contained RNA for these factors as detected by
RT-PCR. CM was able to induce angiogenesis in canine vascular endothelial cells. MCP-1 and MIP-1a increased cell migration
of MSC while VEGF reduced it. H9c2 cells treated with CM under hypoxic conditions for 24 hours displayed a 16% reduction
in caspase-3 activity compared to controls. PI 3-kinase c inhibitor had no effect on controls but reversed the effect of CM on
caspase-3 activity. MCP-1 alone mimicked the protective effect of CM while the PI 3-Kc inhibitor did not reverse the effect of
MCP-1. CM reduced phospho-BAD (Ser112) and phospho-Akt (Ser473) while increasing phospho-Akt (Thr308). MCP-1
reduced the level of phospho-Akt (Ser473) while having no effect on the other two; the PI 3-Kc inhibitor did not alter the
MCP-1 effect. ERK 1/2 phosphorylation was reduced in CM treated H9c2 cells, and inhibition of ERK 1/2 reduced the
phosphorylation of Akt (Ser473), Akt (Thr308) and Bad (Ser112). In conclusion, MSC synthesize and secrete multiple
paracrine factors that are able to affect MSC migration, promote angiogenesis and reduce apoptosis. While both MCP-1 and
PI3-kinase are involved in the protective effect, they are independent of each other. It is likely that multiple pro-survival
factors in addition to MCP-1 are secreted by MSC which act on divergent intracellular signaling pathways.
Funding
This work was support by the Illinois Department of Public Health and the National Heart, Lung, and Blood Institute RO1 HL071046