Skin and muscle biopsies from the calf and groin were gathered from 25 patients with CLI. Control samples came from 10 orthopedic patients and from 5 patients who were undergoing coronary artery bypass. The concentration of VEGF and FGF-2 in the biopsies was measured by enzyme-linked immunoassay, and to localize growth factor production, biopsied sections were immunostained.
Patients with CLI had lower levels of VEGF in distal skin samples than in proximal ones (mean difference: 16.7 pg/mg total protein, 95 % confidence interval: −1.0 to −32.3, P = .038), but these levels were similar to those in distal samples from control subjects (8.0, −4.6 to 20.5, P = .65). In muscle, VEGF concentrations were similar in calf and groin (5.4, −12.4 to 23.1, P = .55), but distal levels were higher than in distal samples from control subjects (23.7, 1.2 to 56.7, P = .028). Skin FGF levels tended to be higher in distal samples (45.3, 26.5 to 117.5, P = .090) and were higher than in skin from control subjects (106.2, −11.4 to 223.8, P = .050). Also in muscle, distal samples had higher levels of FGF-2 (35.6, −1.6 to 59.7, P = .006), but these levels were similar to what was found in control subjects (29.4., −16.3 to 81.2, P = .39). Growth factors were located in connective tissue between muscle fibers. In skin, the predominant FGF-2 staining was just below the epidermal layer, whereas VEGF appeared in the dermal layer.
The results indicate that there are elevated concentrations of FGF-2 in calf muscle, whereas VEGF concentrations do not appear to be higher in the ischemic part of the leg in patients with CLI. These findings suggest that VEGF supplementation may be a more appropriate strategy for therapeutic angiogenesis to the calf area for CLI than FGF-2.