Alpha2(VIII) collagen substrata enhance endothelial cell retention under acute shear stress flow via an alpha2beta1 integrin-dependent mechanism: an in vitro and in vivo study.
BACKGROUND
Essential to tissue-engineered vascular grafts is the formation of a functional endothelial monolayer capable of resisting the forces of blood flow. This study targeted alpha2(VIII) collagen, a major component of the subendothelial matrix, and examined the ability of and mechanisms by which endothelial cells attach to this collagen under static and dynamic conditions both in vitro and in vivo.


RESULTS
Attachment of human endothelial cells to recombinant alpha2(VIII) collagen was assessed in vitro under static and shear conditions of up to 100 dyne/cm2. Alpha2(VIII) collagen supported endothelial cell attachment in a dose-dependent manner, with an 18-fold higher affinity for endothelial cells compared with fibronectin. Cell attachment was significantly inhibited by function-blocking anti-alpha2 (56%) and -beta1 (98%) integrin antibodies but was not RGD dependent. Under flow, endothelial cells were retained at significantly higher levels on alpha2(VIII) collagen (53% and 51%) than either fibronectin (23% and 16%) or glass substrata (7% and 1%) at shear rates of 30 and 60 dyne/cm2, respectively. In vivo studies, using endothelialized polyurethane grafts, demonstrated significantly higher cell retention rates to alpha2(VIII) collagen-coated than to fibronectin-coated prostheses in the midgraft area (P < 0.05) after 24 hours' implantation in the caprine carotid artery.


CONCLUSIONS
These studies demonstrate that alpha2(VIII) collagen has the potential to improve both initial cell attachment and retention of endothelial cells on vascular grafts in vivo, which opens new avenues of research into the development of single-stage endothelialized prostheses and the next generation of tissue-engineered vascular grafts.
Turner
Neill J
NJ
UK Centre for Tissue Engineering, Manchester, United Kingdom.
Murphy
Michael O
MO
Kielty
Cay M
CM
Shuttleworth
C Adrian
CA
Black
Richard A
RA
Humphries
Martin J
MJ
Walker
Michael G
MG
Canfield
Ann E
AE
D000818:Animals; D002448:Cell Adhesion / Q000502:physiology*; D024102:Collagen Type VIII / Q000235:genetics / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006041:Goats; D006801:Humans; D038982:Integrin alpha2beta1 / Q000502:physiology*; D016023:Integrins / Q000502:physiology; D023421:Models, Animal; D011140:Polyurethanes; D011994:Recombinant Proteins / Q000378:metabolism; D013314:Stress, Mechanical
C443712:COL8A2 protein, human; D024102:Collagen Type VIII; D038982:Integrin alpha2beta1; D016023:Integrins; D011140:Polyurethanes; D011994:Recombinant Proteins