Effect of Endoluminal PTFE Graft Placement on Cell Proliferation, PDGF Secretion, and Intimal Hyperplasia

Abstract

To determine the effects of intraluminal placement on peri-anastomotic intimal hyperplasia and platelet derived growth factor (PDGF) secretion in polytetrafluoroethylene (PTFE) grafts. Infrarenal aortic PTFE grafts were placed in 30 dogs as either interposition (n= 12) or intraluminal stented (n= 18) grafts. Grafts were explanted at 4 and 8 weeks. At each anastomosis, intima to media height ratios (IMHR) were calculated, and smooth muscle (Actin), proliferating (PCNA), and PDGF secreting cell content determined using cell-specific immunohistochemical stains. At the proximal anastomosis, control and stented graft IMHRs were 1.01 ± 0.16 vs 0.59 ± 0.18 in 4-week and 1.42 ± 0.16 vs 0.50 ± 0.14 in 8-week specimens. Similar IMHR values were present for the distal anastomosis. Peri-anastomotic PCNA cell counts were greater in control grafts at both 4 and 8 weeks. Stented grafts were associated with diminished IMHR and PCNA+ content at both 4 and 8 weeks (P< 0.05). PDGF+ content was similar among control and stented grafts at 4 weeks, while lower in stented grafts at 8 weeks (P< 0.05). At the distal anastomosis, a correlation between PDGF secretion and Actin+ cell content was observed in control grafts at 4 (r= 0.74) and 8 (r= −0.56) weeks. Cell proliferation was associated with PDGF content in 4-week intraluminal and 8-week control grafts (P< 0.05). Changes in IMHR were not the result of differential PDGF secretion. Intraluminal location attenuates intimal hyperplasia in PTFE grafts. The reduced intimal hyperplasia and improved healing of endoluminal grafts could not be attributed to lower PDGF content alone.