Sustained inhibition of experimental neointimal hyperplasia with a genetically modified herpes simplex virus.
OBJECTIVE
Reported herein is a potential strategy for sustained smooth muscle cell (SMC) inhibition with a virulence-attenuated herpes simplex virus (HSV). Experiments were conducted in vitro to demonstrate selective SMC cytotoxicity and in vivo to demonstrate reduced neointimal hyperplasia (NIH) in a clinically relevant animal model.


METHODS
In vitro: Cultured human umbilical artery smooth muscle cells (UASMC) and venous endothelial cells (HUVEC) were exposed to varying multiplicities of infection (MOI) of a gamma(1)34.5-deleted HSV-1 virus (R849). Cell survival was assessed at 48 and 72 hours with a colorimetric MTT viability assay. In vivo: New Zealand White rabbit external jugular veins (n = 21) were exposed to R849 (2.5 x 10(6) pfu/mL) or culture medium at 110 to 120 mm Hg for 10 minutes, then fashioned as vein patches on carotid arteries. Carotid arteries were ligated distally to decrease blood flow and stimulate a hyperplastic response (ultra-low shear stress model). After 2, 4, 12, and 24 weeks, patched segments were perfusion-fixed with glutaraldehyde and morphometrically examined for NIH formation.


RESULTS
In vitro: At 48 hours, R849 exhibited preferential cytotoxicity to UASMC compared with HUVEC, with 11% +/- 10% of UASMCs and 49% +/- 8% of HUVECs surviving after infection with MOI = 25 (P <.05). Higher MOI resulted in poor survival of both cell lines. In vivo: Blood flow was similarly reduced in all animals both at surgery (0.9 +/- 0.1 mL/min vs 1.6 +/- 0.3 mL/min) and at harvest (2.7 +/- 0.4 mL/min vs 2.5 +/- 0.5 mL/min). R849-infected patches exhibited markedly less NIH than control patches did at 2 weeks (162 +/- 14 microm vs 49 +/- 6 microm; P <.05), 4 weeks (190 +/- 27 microm vs 67 +/- 8 microm; P <.05), and 12 weeks (233 +/- 18 microm vs 113 +/- 2 microm; P <.05).


CONCLUSIONS
The virulence-attenuated HSV strain R849 demonstrates selective cytotoxicity for SMC and is capable of sustained inhibition of NIH in an experimental model of vein graft failure.
Curi
Michael A
MA
Section of Vascular Surgery, Department of Surgery, University of Chicago MC 5028, 5841 S Maryland Ave, Chicago, IL 60637, USA.
Skelly
Christopher L
CL
Meyerson
Shari L
SL
Baldwin
Zachary K
ZK
Balasubramanian
Viji
V
Advani
Sunil J
SJ
Glagov
Seymour
S
Roizman
Bernard
B
Weichselbaum
Ralph R
RR
Schwartz
Lewis B
LB
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects; D005822:Genetic Vectors / Q000627:therapeutic use*; D006801:Humans; D006965:Hyperplasia / Q000188:drug therapy; D066298:In Vitro Techniques; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D011817:Rabbits; D018139:Simplexvirus / Q000235:genetics*; D017539:Tunica Intima / Q000187:drug effects*; D014469:Umbilical Arteries / Q000187:drug effects; D014652:Vascular Diseases / Q000188:drug therapy*