Pk. Shireman et Hp. Greisler, Mitogenicity and release of vascular endothelial growth factor with and without heparin from fibrin glue, J VASC SURG, 31(5), 2000, pp. 936-943
Citations number
12
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Purpose: Fibrin glue (FG) has been used for local cytokine delivery on both
vascular grafts and angioplasty sites. We measured the diffusive release o
f vascular endothelial growth factor (VEGF) and heparin from FG and the mit
ogenic activity of VEGF with and without heparin in FG on canine endothelia
l cells (ECs) and smooth muscle cells (SMCs).
Methods: Release of VEGF labeled with iodine 125 and tritiated heparin from
FG into the overlying media was serially measured over 96 hours, and the d
ata are reported as the mean percent released +/- SD. Proliferation assays
measuring tritiated thymidine incorporation were performed for ECs and SMCs
plated in media with 10% serum on FG containing various concentrations of
VEGF and heparin. Media was placed on the FG for 24 hours and removed befor
e plating cells to minimize the effect of the released, soluble VEGF and he
parin.
Results: At 24 hams, 54% +/- 1% and 58% +/- 1% of the radioactive VEGF and
heparin were released, respectively, with minimal release thereafter (58% /- 1% and 66% +/- 1% at 96 hours). The ECs, SMCs, or media only (no cells)
was plated an FG containing radioactive VEGF in an immediate or 24-hour del
ayed fashion for 72 hours to determine the percent release of VEGF into the
media with the two different methods of plating. Cell type and the presenc
e or absence of cells did not affect VEGF release, but there was three time
s more VEGF in the media for the immediate versus delayed plating (P < .001
). Without heparin, VEGF at 100 ng/mL, or more in the FG was needed to indu
ce EC proliferation. Heparin at 5 U/mL, enhanced EC proliferation at the VE
GF dose of 100 ng/mL, as compared with no heparin (P < .001), but not at th
e VEGF dose of 1000 ng/mL, which Likely represents a maximal response. With
heparin at 500 U/mL, the ECs died. In contrast, VEGF, in the presence or a
bsence of heparin, did not affect SMC proliferation.
Conclusions: We conclude that FG with VEGF at 1000 ng/mL, and heparin at 5
U/mL is the optimal concentration for in vivo use because this may encourag
e EC, but not SMC, proliferation. The VEGF at 1000 ng/mL, should leave mito
genic concentrations of VEGF intact after the initial, diffusive loss, and
the addition of heparin at 5 U/mL may enhance VEGF mitogenic activity.