Beta3-integrins rather than beta1-integrins dominate integrin-matrix interactions involved in postinjury smooth muscle cell migration.
BACKGROUND
Smooth muscle cell (SMC) migration is a vital component in the response of the arterial wall to revascularization injury. Cell surface integrin-extracellular matrix interactions are essential for cell migration. SMCs express both beta1- and beta3-integrins. In this study, we examined the relative functional roles of beta1- and beta3-integrin-matrix interactions in postinjury SMC migration.


RESULTS
Flow cytometry and fluorescence microscopy of migrating SMCs immunostained with anti-beta1 and anti-alpha(v)beta3/5 antibodies (Abs) revealed expression of both beta1- and beta3-integrins, with beta1 observed as linear streaks and beta3 found in focal contacts. In a scrape-wound migration assay, anti-beta1 Abs (92.0+/-10.7% of control, P=.1) and 0.5 mmol/L linear RGD (105+/-5% of control, P=.2) did not alter SMC migration at 48 hours after injury. Beta3-blockade, however, via Abs (anti-beta3/5 35.7+/-4.5% of control, anti-beta3 61+/-12% of control, both P<.001) and cyclic RGD (0.5 mmol/L) (12+/-10% of control, P<.001) decreased migration. Neither beta1- nor beta3-inhibition altered postinjury [3H]thymidine incorporation. In the rat carotid injury model, local adventitial polymer-based delivery of radiolabeled linear or cyclic RGD led to uptake and retention of label, for both peptides, over a 72-hour period after injury. Local arterial wall beta1-blockade via polymer-based delivery of linear RGD had no effect on SMC migration at 4.5 days (11.5+/-3.2 versus 12.8 SMCs per x600 field [control], P=.6) or on neointimal thickening at 14 days (I/M area ratio, 0.664+/-0.328 versus 1.179+/-0.324 [control], P=.6) after injury. In contrast, local beta3-blockade via cRGD limited migration (0.8+/-0.8 versus 12.8+/-4.4 SMCs per x600 field [control], P<.01) and thickening (I/M area ratio, 0.004+/-0.008 versus 1.179+/-0.324 [control], P<.01).


CONCLUSIONS
In postinjury migrating SMCs, beta3- rather than beta1-integrin-matrix interactions are of greater functional significance in adhesive processes essential for SMC migration in vitro and in vivo. Blockade of dominant SMC integrin (beta3)-matrix interactions may be a valuable approach for limiting injury-induced SMC migration and late arterial renarrowing.
Slepian
M J
MJ
University Heart Center, University of Arizona, Tuscon 85724, USA. slepian@u.arizona. edu
Massia
S P
SP
Dehdashti
B
B
Fritz
A
A
Whitesell
L
L
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D002339:Carotid Arteries / Q000473:pathology; D020212:Carotid Artery Injuries; D002404:Catheterization / Q000009:adverse effects; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000293:injuries* / Q000473:pathology; D005109:Extracellular Matrix / Q000502:physiology*; D005353:Fibronectins / Q000494:pharmacology; D005434:Flow Cytometry; D019012:Integrin beta1 / Q000502:physiology; D039661:Integrin beta3; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000737:chemistry / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology / Q000502:physiology; D010980:Platelet Membrane Glycoproteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019096:Vitronectin / Q000494:pharmacology; D014945:Wound Healing
D015703:Antigens, CD; D005353:Fibronectins; C085636:GpenGRGDSPCA; D019012:Integrin beta1; D039661:Integrin beta3; D009842:Oligopeptides; D010980:Platelet Membrane Glycoproteins; D019096:Vitronectin; C101396:glycyl-arginyl-alanyl-aspartyl-seryl-proline; C047981:arginyl-glycyl-aspartic acid; C058161:glycyl-arginyl-glycyl-aspartyl-seryl-proline