Timing and targeting of cell-based VEGF165 gene expression in ischemic tissue.
BACKGROUND
Therapeutic angiogenesis has become a key technology in experimental and clinical medicine. Only few data are available on the effects of timing and targeting of therapeutic proteins after cell-based gene transfer. This work investigates such effects after temporary expression of vascular endothelial growth factor 165 (VEGF(165)), the most commonly used angiogenic protein for therapeutic purposes.


METHODS
We established a cell-based gene-transfer model using fibroblasts to temporarily produce VEGF(165). Cells were implanted into 40 rats. Protein expression and angiogenic effects were measured by PCR, immunohistology, and microangiography. To determine an improvement for survival of ischemically challenged tissue, cells were implanted in an ischemic flap model at different locations and time points.


RESULTS
After implantation of modified cells, a temporary increase was found in the target tissue for VEGF(165), endothelial cell counts, and capillary network formations. Four wk later, histological alterations in the target tissue area were not different from controls. Implantation of modified cells into flap plus wound margin 1 wk before surgery showed significant improvement of tissue survival demonstrated by planimetric measurements and blood vessels counting in the target tissue.


CONCLUSIONS
In our model, temporary expression of VEGF(165) induces therapeutically relevant angiogenesis and improves blood supply only if applied 1 wk before ischemia. It is essential to include the surrounding area for induction of angiogenesis in this model. In contrast, the angiogenic effects are not effective in the target area and its surrounding tissue, if therapeutic gene expression is started during onset of ischemia or 2 wk before ischemia in this model.
Spanholtz
Timo
T
Department of Plastic and Hand Surgery, Burn Care Center, University Clinics Witten/Herdecke, Campus Köln, Merheim, Germany. timo@spanholtz.net
Maichle
Alexandra
A
Niedworok
Christian
C
Stoeckelhuber
Beate M
BM
Krüger
Stefan
S
Wedel
Thilo
T
Aach
Til
T
Middeler
Guido
G
Hellwig-Bürgel
Thomas
T
Bader
Augustinus
A
Krengel
Sven
S
Müller
Oliver J
OJ
Franz
Wolfgang M
WM
Lindenmaier
Werner
W
Machens
Hans-Guenther
HG
D000256:Adenoviridae; D000818:Animals; D049109:Cell Proliferation; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology; D023421:Models, Animal; D018919:Neovascularization, Physiologic / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013524:Surgical Flaps / Q000098:blood supply; D013997:Time Factors; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat