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Activin Receptor-Like Kinase 5 Inhibition Reverses Impairment of Endothelial Cell Viability by Endogenous Islet Mesenchymal Stromal Cells

Activin Receptor-Like Kinase 5 Inhibition Reverses Impairment of Endothelial Cell Viability by Endogenous Islet Mesenchymal Stromal Cells
Activin Receptor-Like Kinase 5 Inhibition Reverses Impairment of Endothelial Cell Viability by Endogenous Islet Mesenchymal Stromal Cells
Following islet transplantation, islet graft revascularization is compromised due to loss of endothelial cells (ECs) during islet culture. TGF-? signaling pathways are essential for vascular homeostasis but their importance for islet EC function is unclear. We have identified a population of multipotent mesenchymal stromal cells (MSCs) within islets and investigated how modulation of TGF-? signaling by these cells influences islet EC viability. Cultured islets exhibited reduced expression of EC markers (VEGFR2; VE-cadherin; CD31) which was associated with diminished but sustained expression of endoglin a marker of both ECs and MSCs. Double fluorescent labelling of islets in situ with the EC marker CD31 disclosed a population of CD31-negative cells which were positive for endoglin. In vitro co-culture of microvascular ECs with endoglin-positive, CD31-negative islet MSCs reduced VEGFR2 protein expression, disrupted EC angiogenic behaviour and increased EC detachment. Medium conditioned by islet MSCs significantly decreased EC viability and increased EC caspase 3/7 activity. EC:MSC co-cultures showed enhanced Smad2 phosphorylation consistent with altered ALK5 signalling. Pharmacological inhibition of ALK5 activity with SB431542 (SB) improved EC survival upon contact with MSCs, and SB-treated cultured islets retained EC marker expression and sensitivity to exogenous VEGF164. Thus, endoglin-expressing islet MSCs influence EC ALK5 signalling in vitro, which decreases EC viability, and changes in ALK5 activity in whole cultured islets contribute to islet EC loss. Modifying TGF-? signalling may enable maintenance of islet ECs during islet isolation and thus improve islet graft revascularization post-transplantation
islet mesenchymal stromal cell, endoglin, endothelial cell, TGF-?
0250-6793
547-559
Clarkin, Claire E.
05cd2a88-1127-41aa-a29b-7ac323b4f3c9
King, Aileen J.
52124eba-f8c3-4d2c-bdc1-07c6cfa19523
Dhadda, Paramjeet
043d3432-b285-4a11-896a-6592db2311dd
Chagastelles, Pedro
8593a899-002b-4eda-b20c-a2443ce29c09
Nardi, Nance
102926b2-7fc7-49e9-8fd6-d69e0f20aee6
Wheeler-Jones, Caroline P.
c5bcaf30-9554-4c43-82d9-dbcdc1cac981
Jones, Peter M.
38a5ea85-3372-4389-bbf0-f4330dd86f6d
Clarkin, Claire E.
05cd2a88-1127-41aa-a29b-7ac323b4f3c9
King, Aileen J.
52124eba-f8c3-4d2c-bdc1-07c6cfa19523
Dhadda, Paramjeet
043d3432-b285-4a11-896a-6592db2311dd
Chagastelles, Pedro
8593a899-002b-4eda-b20c-a2443ce29c09
Nardi, Nance
102926b2-7fc7-49e9-8fd6-d69e0f20aee6
Wheeler-Jones, Caroline P.
c5bcaf30-9554-4c43-82d9-dbcdc1cac981
Jones, Peter M.
38a5ea85-3372-4389-bbf0-f4330dd86f6d

Clarkin, Claire E., King, Aileen J., Dhadda, Paramjeet, Chagastelles, Pedro, Nardi, Nance, Wheeler-Jones, Caroline P. and Jones, Peter M. (2013) Activin Receptor-Like Kinase 5 Inhibition Reverses Impairment of Endothelial Cell Viability by Endogenous Islet Mesenchymal Stromal Cells. Stem Cells, 31 (3), 547-559. (doi:10.1002/stem.1305).

Record type: Article

Abstract

Following islet transplantation, islet graft revascularization is compromised due to loss of endothelial cells (ECs) during islet culture. TGF-? signaling pathways are essential for vascular homeostasis but their importance for islet EC function is unclear. We have identified a population of multipotent mesenchymal stromal cells (MSCs) within islets and investigated how modulation of TGF-? signaling by these cells influences islet EC viability. Cultured islets exhibited reduced expression of EC markers (VEGFR2; VE-cadherin; CD31) which was associated with diminished but sustained expression of endoglin a marker of both ECs and MSCs. Double fluorescent labelling of islets in situ with the EC marker CD31 disclosed a population of CD31-negative cells which were positive for endoglin. In vitro co-culture of microvascular ECs with endoglin-positive, CD31-negative islet MSCs reduced VEGFR2 protein expression, disrupted EC angiogenic behaviour and increased EC detachment. Medium conditioned by islet MSCs significantly decreased EC viability and increased EC caspase 3/7 activity. EC:MSC co-cultures showed enhanced Smad2 phosphorylation consistent with altered ALK5 signalling. Pharmacological inhibition of ALK5 activity with SB431542 (SB) improved EC survival upon contact with MSCs, and SB-treated cultured islets retained EC marker expression and sensitivity to exogenous VEGF164. Thus, endoglin-expressing islet MSCs influence EC ALK5 signalling in vitro, which decreases EC viability, and changes in ALK5 activity in whole cultured islets contribute to islet EC loss. Modifying TGF-? signalling may enable maintenance of islet ECs during islet isolation and thus improve islet graft revascularization post-transplantation

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More information

Published date: 2013
Keywords: islet mesenchymal stromal cell, endoglin, endothelial cell, TGF-?
Organisations: Biomedicine

Identifiers

Local EPrints ID: 346602
URI: https://eprints.soton.ac.uk/id/eprint/346602
ISSN: 0250-6793
PURE UUID: 6f15993b-90ec-4477-a40c-b646fa8a7c8b

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Date deposited: 03 Jan 2013 09:37
Last modified: 16 Jul 2019 21:47

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