Regulation of new blood vessel growth into ischemic skeletal muscle.
OBJECTIVE
In a rabbit model, transposition of a muscle pedicle flap to an ischemic hind limb has been shown to result in the development of new blood vessels that connect the arterial circulation of the flap to the circulation of the limb. The hypothesis that exogenous recombinant basic fibroblast growth factor (bFGF) would enhance the development of this new blood supply was examined and the regulation of bFGF in this process was investigated.


METHODS
The right common iliac artery was ligated in 12 male New Zealand white rabbits. An abdominal wall muscle flap based on the left inferior epigastric artery was transposed to the right thigh. bFGF in phosphate-buffered saline (PBS) at 3 ng/h (n = 6), or PBS alone (n = 6), was infused for 7 days via mini-osmotic pumps with an infusion catheter positioned at the flap-muscle interface. The flap-muscle interface was immunostained with anti-alpha-actin antibody to determine blood vessel density (number of vessels/mm) and with anti-bFGF antibody to evaluate bFGF distribution. RNA was isolated from these sections, and polymerase chain reaction (PCR) was used to examine endogenous bFGF messenger RNA (mRNA) expression.


RESULTS
Blood vessel density was significantly increased in animals receiving exogenous bFGF (22. 0 +/- 10.6 vessels/mm vs. 10.7 +/- 8.8 vessels/mm, P =.009). In the controls, neovessels were arranged in clusters with endogenous bFGF concentrated around these clusters. In bFGF-treated animals, vessels were diffusely scattered throughout the flap-limb interface, corresponding to the distribution pattern of infused bFGF. There was no difference in bFGF mRNA expression between the control and the bFGF-treated groups.


CONCLUSIONS
Exogenous bFGF infusion significantly augmented new blood vessel development at the flap-limb interface. Endogenous bFGF was up-regulated around the newly developed microvessels in control animals, and vessel growth correlated with the diffuse distribution of exogenous bFGF, implicating bFGF as an important factor in angiogenesis. Exogenous bFGF did not affect bFGF mRNA expression, suggesting that the regulation of bFGF is not under autocrine control.
Bush
R L
RL
Department of Surgery, and the Department of Pathology, University of California Medical Center, Davis, and the Department of Molecular Biology, Shriners Childrens Hospital, Tampa, FL, USA.
Pevec
W C
WC
Ndoye
A
A
Cheung
A T
AT
Sasse
J
J
Pearson
D N
DN
D000818:Animals; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis / Q000494:pharmacology*; D006614:Hindlimb / Q000098:blood supply; D007150:Immunohistochemistry; D007511:Ischemia / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D018919:Neovascularization, Physiologic; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D013524:Surgical Flaps / Q000098:blood supply* / Q000473:pathology
D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2