Comparison of Surgisis, AlloDerm, and Vicryl Woven Mesh grafts for abdominal wall defect repair in an animal model.

BACKGROUND: Surgisis and AlloDerm, two biosynthetic materials, have been previously used with success in abdominal wall repairs in the setting of contaminated fields. Historically, Vicryl Woven Mesh, a synthetic material, has also been used in such settings as a temporary bridge for abdominal wall reconstruction. This study compares Surgisis and AlloDerm with Vicryl Woven Mesh with respect to tensile strength, collagen remodeling, and neovascularization using a rat hernia model. METHODS: A prospective randomized trial of 54 Sprague-Dawley rats were assigned to the Surgisis, AlloDerm, or Vicryl Woven Mesh group with baseline, 30-day, and 60-day end points. A 1.5-cm x 5.0-cm defect was created in the right abdominis rectus muscle and repaired with an underlay bridge graft using the different treatment materials. Tensile strength was measured using an Instron tensiometer. Histologic specimens were evaluated for neovascularization, collagen deposition, and collagen organization at the 30- and 60-day time points. RESULTS: Surgisis had significantly greater tensile strength compared to Vicryl Woven Mesh at the baseline time point (0.142 vs. 0.091 MPa, p < 0.05). There were no differences between groups tensile strength at 30 or 60 days postoperatively. The Vicryl Woven Mesh and AlloDerm groups showed increases in tensile strength at 30 days postoperatively versus baseline (p < 0.05). Vicryl Woven Mesh, Surgisis, and AlloDerm all showed increases in tensile strength at 60 days postoperatively compared to 30 days postoperatively and at baseline (p < 0.05). Surgisis and AlloDerm had significantly greater (p < 0.05) amounts of collagen deposition and organization at 30 and 60 days compared to Vicryl Woven Mesh. There was no significant difference between AlloDerm and Surgisis with respect to collagen deposition and organization. Surgisis and AlloDerm showed a significantly greater amount (p < 0.05) of neovascularization than Vicryl Woven Mesh at both time points. In addition, Surgisis had a significantly greater amount (p < 0.05) of neovascularization than AlloDerm at both 30 and 60 days. CONCLUSION: Surgisis has increased baseline tensile strength compared to Vicryl Woven Mesh. Tensile strength in Vicryl Woven Mesh is equal to biosynthetic grafts after tissue incorporation. Biosynthetic grafts showed superior collagen deposition and organization. Surgisis mesh showed increased neovascularization over both AlloDerm and Vicryl Woven Mesh.

Permacol (porcine dermal collagen) and Alloderm (acellular cadaveric dermis) as a vascular patch repair for common carotid arteriotomy in a rabbit model.

Occult injuries to arteries are common in trauma and evolution of their repair has been observed throughout military conflicts. Currently, autogenous vein and polytetrafluoroethylene (PTFE) are used as patch agents for arterial trauma. However, suitable vein is often lacking in multitrauma patients, and PTFE is prone to infection in the contaminated combat wound. The purpose of this study is to evaluate Permacol, porcine dermal collagen, and Alloderm, acellular cadaveric dermis, as suitable alternatives to PTFE with the potential benefit of being used in contaminated wounds. A New Zealand White rabbit common carotid arteriotomy model was used to compare Permacol (n = 12), Alloderm (n = 11), and PTFE (n = 13) for patch repair. Thrombin generation was examined using an enzyme-linked immunosorbent assay for thrombin-antithrombin complex. Histological samples were taken to analyze vessel lumen area, vessel diameter, intimal thickness, and medial thickness. Pathological examinations were made to compare rates of intimal hyperplasia, aneurysm, patency, and thrombus formation. The Permacol group showed equivalent rates of thrombus, aneurysm, and patency compared with PTFE. Increased lumen area was seen in the Permacol group, 0.344 mm2 (p = 0.02) compared with the PTFE group, 0.204 mm2. Permacol also had decreased incidence of intimal hyperplasia compared with PTFE, 50.0% versus 92% (p < 0.05). Alloderm had increased rates of aneurysm formation, 63.6% (p = 0.004) compared with PTFE, 0.0%, and Permacol groups, 8.3%. Alloderm also had increased intimal thickness through the patch, 0.076 mm (p = 0.18), compared with PTFE, 0.026 mm, and Permacol groups, 0.024 mm. Vessel diameter through the patch showed the Alloderm group, 1.87 mm (p = 0.004), was significantly larger than both the Permacol, 1.41 mm, and PTFE groups, 1.28 mm. Furthermore, Alloderm showed leukocyte migration around the patch. Enzyme-linked immunosorbent assay for thrombin-antithrombin complex was only elevated for PTFE in the 7-day postoperative measurement but was not statistically different from the other groups. Permacol has characteristics to be an effective alternative for PTFE for patch arteriotomy repair in our rabbit model. Futher studies need to be conducted to investigate the potential of Permacol in vascular trauma. Alloderm is not a suitable alternative to PTFE for patch arteriotomy repair.

Evaluation of the effect of sildenafil and vascular endothelium growth factor combination treatment on skin flap survival in rats.

BACKGROUND: Distal ischemic necrosis of surgical flaps remains a challenging problem for the reconstructive surgeon. Recent studies have shown that either sildenafil or vascular endothelium growth factor (VEGF) treatment significantly improves ischemic skin flap viability. In this study, the effect of the combination of sildenafil and VEGF165 was evaluated on a rat skin flap model using orthogonal polarization spectral imaging and histologic analysis. METHODS: Rats were assigned to either a sham (n = 31), vehicle (n = 24), sildenafil (n = 24), VEGF (n = 23), or sildenafil and VEGF combination treatment (n = 21) groups. Distances from the distal end of the flap to avascular, stasis, and normal capillary blood flow zones were determined using orthogonal polarization spectral imaging on a skin flap model. Vessel density assessment was done at 7 days post surgery. RESULTS: Imaging analysis showed significant reduction in avascular and stasis areas in sildenafil and VEGF combination-treated groups at 7 days post surgery (p < 0.05). The combination-treated group, however, was not significantly different when compared to the group treated with sildenafil only. The sildenafil-treated group showed a significant (p < 0.05) reduction in both areas at day 7 compared to the VEGF and control groups. Histologic analysis showed no significant differences in vessel density between the groups. CONCLUSION: The combination of sildenafil and VEGF decreases the extent of avascular and stasis zones in skin flaps. The skin flap improvement seen with the combination treatment was similar to the sildenafil treatment alone suggesting that enhanced flap survival was due solely to the effect of sildenafil.