Abstract
The existence of multipotent cardiac stromal cells expressing stem cell antigen (Sca)-1 has been reported, and their proangiogenic properties have been demonstrated in myocardial infarction models. In this study, we tested the hypothesis that stimulation of adenosine receptors on cardiac Sca-1+ cells up-regulates their secretion of proangiogenic factors. We found that Sca-1 is expressed in subsets of mouse cardiac stromal CD31− and endothelial CD31+ cells. The population of Sca-1+CD31+ endothelial cells was significantly reduced, whereas the population of Sca-1+CD31− stromal cells was increased 1 week after myocardial infarction, indicating their relative functional importance in this pathophysiological process. An increase in adenosine levels in adenosine deaminase-deficient mice in vivo significantly augmented vascular endothelial growth factor (VEGF) production in cardiac Sca-1+CD31− stromal cells but not in Sca-1+CD31+ endothelial cells. We found that mouse cardiac Sca-1+CD31− stromal cells predominantly express mRNA encoding A2B adenosine receptors. Stimulation of adenosine receptors significantly increased interleukin (IL)-6, CXCL1 (a mouse ortholog of human IL-8), and VEGF release from these cells. Using conditionally immortalized Sca-1+CD31− stromal cells obtained from wild-type and A2B receptor knockout mouse hearts, we demonstrated that A2B receptors are essential for adenosine-dependent up-regulation of their paracrine functions. We found that the human heart also harbors a population of stromal cells similar to the mouse cardiac Sca-1+CD31− stromal cells that increase release of IL-6, IL-8, and VEGF in response to A2B receptor stimulation. Thus, our study identified A2B adenosine receptors on cardiac stromal cells as potential targets for up-regulation of proangiogenic factors in the ischemic heart.
Footnotes
This work was supported by the National Institutes of Health National Heart, Lung, and Blood Institute [Grant R01-HL095787]; National Institutes of Health National Cancer Institute [Grant R01-CA138923]; and National Institutes of Health National Center for Research Resources [Clinical and Translational Science Award UL1-RR024975-01, Vanderbilt Institute for Clinical and Translational Research Clinical and Translational Science Award Grant VR750].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
ABBREVIATIONS:
- Sca-1
- stem cell antigen-1
- DMEM
- Dulbecco's modified Eagle's medium
- HG
- high glucose
- LG
- low glucose
- IFNγ
- interferon γ
- PSB-603
- 8-[4-[4-((4-chlorophenzyl)piperazide-1-sulfonyl)phenyl]]-1-propylxanthine
- SCH58261
- 5-amino-7-(phenylethyl)-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]-pyrimidine
- NECA
- 5′-N-ethylcarboxamidoadenosine
- FBS
- fetal bovine serum
- DMSO
- dimethyl sulfoxide
- A2BKO
- A2B adenosine receptor knockout
- WT
- wild type
- ADA
- adenosine deaminase
- PBS
- phosphate-buffered saline
- BSA
- bovine serum albumin
- PE
- phycoerythrin
- FITC
- fluorescein isothiocyanate
- VEGF
- vascular endothelial growth factor
- RT-PCR
- reverse transcription-polymerase chain reaction.
- Received December 6, 2011.
- Accepted March 12, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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