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Tissue-Specific Stem Cells
Article first published online: 20 SEP 2012
Copyright © 2012 AlphaMed Press
Volume 30, Issue 10, pages 2283–2296, October 2012
How to Cite
YlÖstalo, J. H., Bartosh, T. J., Coble, K. and Prockop, D. J. (2012), Human Mesenchymal Stem/Stromal Cells Cultured as Spheroids are Self-activated to Produce Prostaglandin E2 that Directs Stimulated Macrophages into an Anti-inflammatory Phenotype. STEM CELLS, 30: 2283–2296. doi: 10.1002/stem.1191
Author contributions: J.H.Y. and T.J.B.: conception and design, provision of study material or patients, collection and/or assembly of data, data analysis and interpretation, and manuscript writing; K.C.: provision of study material or patients; D.J.P.: financial support, data analysis and interpretation, manuscript writing, and final approval of manuscript. J.H.Y. and T.J.B. contributed equally to this article.
Disclosure of potential conflicts of interest is found at the end of this article.
First published online in STEM CELLSEXPRESS May 31, 2012.
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Accepted manuscript online: 3 AUG 2012 02:26PM EST
- Manuscript Accepted: 12 JUL 2012
- Manuscript Received: 9 APR 2012
- NIH. Grant Number: P40 RR 17447
- CPRIT application RP110620. Grant Number: RP110553-P1
Culturing cells in three dimension (3D) provides an insight into their characteristics in vivo. We previously reported that human mesenchymal stem/stromal cells (hMSCs) cultured as 3D spheroids acquire enhanced anti-inflammatory properties. Here, we explored the effects of hMSC spheroids on macrophages that are critical cells in the regulation of inflammation. Conditioned medium (CM) from hMSC spheroids inhibited lipopolysaccharide-stimulated macrophages from secreting proinflammatory cytokines TNFα, CXCL2, IL6, IL12p40, and IL23. CM also increased the secretion of anti-inflammatory cytokines IL10 and IL1ra by the stimulated macrophages, and augmented expression of CD206, a marker of alternatively activated M2 macrophages. The principal anti-inflammatory activity in CM had a small molecular weight, and microarray data suggested that it was prostaglandin E2 (PGE2). This was confirmed by the observations that PGE2 levels were markedly elevated in hMSC spheroid-CM, and that the anti-inflammatory activity was abolished by an inhibitor of cyclooxygenase-2 (COX-2), a silencing RNA for COX-2, and an antibody to PGE2. The anti-inflammatory effects of the PGE2 on stimulated macrophages were mediated by the EP4 receptor. Spheroids formed by human adult dermal fibroblasts produced low levels of PGE2 and displayed negligible anti-inflammatory effects on stimulated macrophages, suggesting the features as unique to hMSCs. Moreover, production of PGE2 by hMSC spheroids was dependent on the activity of caspases and NFκB activation in the hMSCs. The results indicated that hMSCs in 3D-spheroid cultures are self-activated, in part by intracellular stress responses, to produce PGE2 that can change stimulated macrophages from a primarily proinflammatory M1 phenotype to a more anti-inflammatory M2 phenotype. STEM Cells2012;30:2283–2296