Genetic engineering of stent grafts with a highly efficient pseudotyped retroviral vector

Purpose: The purpose of this study was first to compare the gene transfer efficiency of amphotrophic murine leukemia viral vector (ampho–MuLV) with the efficiency of MuLV pseudotyped with the vesicular stomatitis virus G glycoprotein (VSVG–MuLV) in tissue of vascular origin. The second purpose of this study was to determine cell retention after the implantation of genetically engineered stent grafts. Methods: Gene transfer efficiency was ascertained with the b-galactosidase assay. The target tissues included endothelial cells (ECs), smooth muscle cells (SMCs), and human saphenous veins (HSVs). Polyurethane stent grafts were suffused with lac Z–transduced ECs and SMCs that were harvested from porcine jugular vein. The grafts were implanted into the iliac artery of each pig whose jugular vein had been harvested. Cell retention was analyzed at 1 and 4 weeks with X-Gal staining. Results: VSVG–MuLV transduction efficiency exceeded that of ampho–MuLV in human ECs (VSVG–MuLV, n = 24, 89% ± 6%; ampho–MuLV, n = 18, 14% ± 6%; P < .001), human SMCs (VSVG–MuLV, n = 5, 92% ± 3%; ampho–MuLV, n = 4, 17% ± 2%; P < .001), pig ECs (VSVG–MuLV, n = 4, 81% ± 2%; ampho–MuLV, n = 4, 13% ± 3%; P < .001), and pig SMCs (VSVG–MuLV, n = 5, 89% ± 3%; ampho–MuLV, n = 4, 16% ± 1%; P < .001). As much as a 10-fold higher transduction efficiency was observed with VSVG–MuLV in HSVs. After the stent graft implantation, the engineered cells were retained and proliferated on the stent membrane, with ingrowth into the underlying intima. Conclusion: VSVG–MuLV significantly increased the gene transfer efficiency in vascular SMCs and ECs and in organ-cultured HSVs. The cells were retained and proliferated on stent grafts for the short term in the pig. (J Vasc Surg 1999;29:863-73.

Dual cell seeding and the use of zymogen tissue plasminogen activator to improve cell retention on polytetrafluoroethylene grafts

AbstractObjective: The purpose of this study was to enhance the retention of seeded endothelial cells (EC) on prosthetic vascular grafts. Dual-layer EC and smooth muscle cell (SMC) seeding and gene transfer of a zymogen tissue plasminogen activator gene (tPA) into seeded EC were studied. Methods: Polytetrafluoroethylene (PTFE) grafts were precoated with fibronectin, seeded with SMC followed by EC a day later, and then, 24 hours later, exposed to an in vitro flow system for 1 hour. Cell retention rates were determined for grafts seeded with EC only, a dual layer of EC on top of SMC, EC transduced with wild-type tPA, and EC transduced with zymogen tPA. Results: Seeding efficiency of PTFE pretreated with fibronectin was 260 ± 8 cell/mm2. After exposure to flow, only 39% ± 14% of the EC were retained when EC were seeded alone, whereas 73% ± 22% of EC remained on grafts when EC were seeded on top of SMC (P <.001, n = 10). The enzyme activity of a mutant zymogen tPA in absence of fibrin was 14 ± 1 IU/mL, which is 3.6-fold lower than that in the presence of fibrin (50 ± 19 IU/mL), whereas fibrin has no effect on the wild-type tPA activity. EC expressing a high level of wild-type tPA had a lower retention rate (37%) when compared with normal EC (45%). EC expressing the mutant zymogen tPA had an improved retention rate (54%, P =.001, n = 10) in absence of fibrin, whereas its retention rate was reduced to 43% when the cells were exposed to fibrin. Conclusion: SMC seeded between EC and PTFE improves EC retention in vitro. Transduction of zymogen tPA increases thrombolytic ability of seeded cells with less adverse impact on cell retention than wild-type tPA. (J Vasc Surg 2001;34:337-43.

Intraaortic Stabilization of the AneuRx Stent-Graft System: A Useful Adjunct to Minimize Device Migration

The deployment of a Medtronic AneuRx stent-graft system for endovascular abdominal aortic aneurysm repair requires a series of precise maneuvers that include positioning the primary delivery catheter in the infrarenal aorta, retracting the graft-covering sheath, and withdrawing the stainless steel runners. The last step allows the stent-graft to fully expand and attach to the non-aneurysmal aorta and iliac arteries. Such maneuvers may cause the stent-graft to move caudally if the device is placed in a severely angulated aortic neck. We describe a simple, coaxial, stabilization technique utilizing the contralateral introducer sheath which minimizes potential caudal migration of the stent-graft in angulated aortic necks during runner withdrawal

Intraaortic Stabilization of the AneuRx Stent-Graft System: A Useful Adjunct to Minimize Device Migration

The deployment of a Medtronic AneuRx stent-graft system for endovascular abdominal aortic aneurysm repair requires a series of precise maneuvers that include positioning the primary delivery catheter in the infrarenal aorta, retracting the graft-covering sheath, and withdrawing the stainless steel runners. The last step allows the stent-graft to fully expand and attach to the non-aneurysmal aorta and iliac arteries. Such maneuvers may cause the stent-graft to move caudally if the device is placed in a severely angulated aortic neck. We describe a simple, coaxial, stabilization technique utilizing the contralateral introducer sheath which minimizes potential caudal migration of the stent-graft in angulated aortic necks during runner withdrawal

In Situ Reconstruction with Cryopreserved Arterial Allografts for Management of Mycotic Aneurysms or Aortic Prosthetic Graft Infections

We designed this study to evaluate a multi-institutional experience regarding the efficacy of cryopreserved aortic allografts in the treatment of infected aortic prosthetic grafts or mycotic aneurysms. We reviewed clinical data of all patients from 4 institutions who underwent in situ aortic reconstruction with cryopreserved allografts for either infected aortic prosthetic graft or mycotic aneurysms from during a 6-year period. Relevant clinical variables and treatment outcomes were analyzed. A total of 42 patients (37 men; overall mean age 63 ± 13 years, range 41–74 years) were identified during this study period. Treatment indications included 34 primary aortic graft infections (81%), 6 mycotic aneurysms (22%), and 2 aortoenteric erosions (5%). Transabdominal and thoracoabdominal approaches were used in 38 (90%) and 4 patients (10%), respectively. Staphylococcus aureus was the most commonly identified organism (n=27, 64%). Although there was no intraoperative death, the 30-day operative mortality was 17% (n=7). There were 21 (50%) nonfatal complications, including local wound infection (n=8), lower-extremity deep venous thrombosis (n=5), amputation (n=6), and renal failure requiring hemodialysis (n=2). The average length of hospital stay was 16.4 ± 7 days. During a mean follow-up period of 12.5 months, reoperation for allograft revision was necessary in 1 patient due to graft thrombosis (6%). The overall treatment mortality rate was 21% (n=9). In situ aortic reconstruction with cryopreserved allografts is an acceptable treatment method in patients with infected aortic prosthetic graft or mycotic aneurysms. Our study showed that mid-term graft-related complications such as reinfection or aneurysmal degeneration were uncommon

In Situ Reconstruction with Cryopreserved Arterial Allografts for Management of Mycotic Aneurysms or Aortic Prosthetic Graft Infections

We designed this study to evaluate a multi-institutional experience regarding the efficacy of cryopreserved aortic allografts in the treatment of infected aortic prosthetic grafts or mycotic aneurysms. We reviewed clinical data of all patients from 4 institutions who underwent in situ aortic reconstruction with cryopreserved allografts for either infected aortic prosthetic graft or mycotic aneurysms from during a 6-year period. Relevant clinical variables and treatment outcomes were analyzed. A total of 42 patients (37 men; overall mean age 63 ± 13 years, range 41–74 years) were identified during this study period. Treatment indications included 34 primary aortic graft infections (81%), 6 mycotic aneurysms (22%), and 2 aortoenteric erosions (5%). Transabdominal and thoracoabdominal approaches were used in 38 (90%) and 4 patients (10%), respectively. Staphylococcus aureus was the most commonly identified organism (n=27, 64%). Although there was no intraoperative death, the 30-day operative mortality was 17% (n=7). There were 21 (50%) nonfatal complications, including local wound infection (n=8), lower-extremity deep venous thrombosis (n=5), amputation (n=6), and renal failure requiring hemodialysis (n=2). The average length of hospital stay was 16.4 ± 7 days. During a mean follow-up period of 12.5 months, reoperation for allograft revision was necessary in 1 patient due to graft thrombosis (6%). The overall treatment mortality rate was 21% (n=9). In situ aortic reconstruction with cryopreserved allografts is an acceptable treatment method in patients with infected aortic prosthetic graft or mycotic aneurysms. Our study showed that mid-term graft-related complications such as reinfection or aneurysmal degeneration were uncommon