Expanded Polytetrafluoroethylene Vascular Grafts Research Articles

Small diameter expanded polytetrafluoroethylene vascular graft with differentiated inner and outer biomacromolecules for collaborative endothelialization, anti-thrombogenicity and anti-inflammation

Without differentiated inner and outer biological function, expanded polytetrafluoroethylene (ePTFE) small-diameter (<6 mm) artificial blood vessels would fail in vivo due to foreign body rejection, thrombosis, and hyperplasia. In order to synergistically promote endothelialization, anti-thrombogenicity, and anti-inflammatory function, we modified the inner and outer surface of ePTFE, respectively, by grafting functional biomolecules, such as heparin and epigallocatechin gallate (EGCG), into the inner surface and polyethyleneimine and rapamycin into the outer surface via layer-by-layer self-assembly. Fourier-transform infrared spectroscopy showed the successful incorporation of EGCG, heparin, and rapamycin. The collaborative release profile of heparin and rapamycin lasted for 42 days, respectively. The inner surface promoted human umbilical vein endothelial cells (HUVECs) adhesion and growth and that the outer surface inhibited smooth muscle cells growth and proliferation. The modified ePTFE effectively regulated the differentiation behavior of RAW264.7, inhibited the expression of proinflammatory mediator TNF-α, and up-regulated the expression of anti-inflammatory genes Arg1 and Tgfb-1. The ex vivo circulation results indicated that the occlusions and total thrombus weight of modified ePTFE was much lower than that of the thrombus formed on the ePTFE, presenting good anti-thrombogenic properties. Hence, the straightforward yet efficient synergistic surface functionalization approach presented a potential resolution for the prospective clinical application of small-diameter ePTFE blood vessel grafts.

Physical shish-kebab modification vs. chemical surface coating on expanded polytetrafluoroethylene vascular grafts for enhanced endothelial cell adhesion

Promoting rapid adhesion of endothelial cells is of significance for the viability of vascular grafts for small-diameter blood vessels (SDBVs) made of expanded polytetrafluoroethylene (ePTFE). Many physical and chemical surface modification methods have been developed to overcome the inertness of ePTFE and to promote cell adhesion. In this study, a biomimetic poly(ε-caprolactone) (PCL) shish-kebab microstructure was formed on the fibrillated domains of ePTFE through induced crystallization. The surface morphology and chemistry, mechanical property, cytocompatibility, and endothelial cell adhesion of PCL shish-kebab modified ePTFE were investigated. The effectiveness of and synergy between this physical topology modification and the traditional chemical RGD dig-coating in terms of cell adhesion were also evaluated. The positive effect of the shish-kebab structure on cell adhesion was found to be more significant than that of RGD coating, and there is a strong synergy between ePTFE surface modification and RGD coating. The biomimetic shish-kebab structure could be a promising material platform for further grafting and/or surface functionalization of ePTFE for other tissue engineering applications.

Pre‐implantation evaluation of a small‐diameter, long vascular graft (Biotube®) for below‐knee bypass surgery in goats

There are no small-diameter, long artificial vascular grafts for below-knee bypass surgery in chronic limb-threatening ischemia. We have developed tissue-engineered vascular grafts called "Biotubes®" using a completely autologous approach called in-body tissue architecture (iBTA). This study aimed at pre-implantation evaluation of Biotube and its in vivo preparation device, Biotube Maker, for use in below-knee bypass surgery.Forty nine makers were subcutaneously embedded into 17 goats for predetermined periods (1, 2, or 3months). All makers produced Biotubes as designed without inflammation over all periods, with the exception of a few cases with minor defects (success rate: 94%). Small hole formation occurred in only a few cases. All Biotubes obtained had an inner diameter of 4 mm and a length of 51 to 52 cm with a wall thickness of 594 ± 97 μm. All Biotubes did not kink when completely bent under an internal pressure of 100 mmHg and did not leak without any deformation under a water pressure of 200 mmHg. Their burst strength was 2409 ± 473 mmHg, and suture retention strength was 1.75 ± 0.27 N, regardless of the embedding period, whereas tensile strength increased from 7.5± 1.3N at 1month to 9.7± 2.0N at 3months with the embedding period. The amount of water leakage from the needle holes prepared in the Biotube wall was approximately 1/7th of that in expanded polytetrafluoroethylene vascular grafts. The Biotubes could be easily connected to each other without cutting or anastomosis leaks. They could be stored for at least 1year at room temperature. This study confirmed that even Biotubes formed 1month after embedding of Biotube Makers had properties comparable to arteries.

A Radiation-Crosslinked Gelatin Hydrogel That Promotes Tissue Incorporation of an Expanded Polytetrafluoroethylene Vascular Graft in Rats.

A prosthetic vascular graft that induces perigraft tissue incorporation may effectively prevent serious sequelae such as seroma formation and infection. Radiation-crosslinked gelatin hydrogel (RXgel) mimics the chemical and physical properties of the in vivo extracellular matrix and may facilitate wound healing by promoting tissue organization. Fibroblasts cultured on RXgel actively migrated into the gel for up to 7 days. RXgels of three different degrees of hardness (Rx[10], soft; Rx[15], middle; Rx[20], hard) were prepared, and small disc-like samples of RXgels were implanted into rats. In vitro and in vivo results indicated that Rx[10] was too soft to coat vascular grafts. Thus, expanded polytetrafluoroethylene (ePTFE) vascular grafts coated with RXgel were developed using Rx[15] and Rx[20] gels, and ring-shaped slices of the graft were implanted into rats. Alpha-smooth muscle actin (αSMA) and type III collagen (Col-III) levels were detected by immunohistochemistry. Immunohistochemical staining for αSMA and Col-III demonstrated that RXgel-coated vascular grafts induced more granulation tissue than non-coated grafts on days 14 and 28 after implantation. RXgel-coated ePTFE vascular grafts may provide a solution for patients by reducing poor perigraft tissue incorporation.

Assessment of Electrospun Pellethane-Based Scaffolds for Vascular Tissue Engineering.

We examined the physicochemical properties and the biocompatibility and hemocompatibility of electrospun 3D matrices produced using polyurethane Pellethane 2363-80A (Pel-80A) blends Pel-80A with gelatin or/and bivalirudin. Two layers of vascular grafts of 1.8 mm in diameter were manufactured and studied for hemocompatibility ex vivo and functioning in the infrarenal position of Wistar rat abdominal aorta in vivo (n = 18). Expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar diameter were implanted as a control (n = 18). Scaffolds produced from Pel-80A with Gel showed high stiffness with a long proportional limit and limited influence of wetting on mechanical characteristics. The electrospun matrices with gelatin have moderate capacity to support cell adhesion and proliferation (~30–47%), whereas vascular grafts with bivalirudin in the inner layer have good hemocompatibility ex vivo. The introduction of bivalirudin into grafts inhibited platelet adhesion and does not lead to a change hemolysis and D-dimers concentration. Study in vivo indicates the advantages of Pel-80A grafts over ePTFE in terms of graft occlusion, calcification level, and blood velocity after 6 months of implantation. The thickness of neointima in Pel-80A–based grafts stabilizes after three months (41.84 ± 20.21 µm) and does not increase until six months, demonstrating potential for long-term functioning without stenosis and as a suitable candidate for subsequent preclinical studies in large animals.

Silk fibroin vascular graft: a promising tissue-engineered scaffold material for abdominal venous system replacement

No alternative tissue-engineered vascular grafts for the abdominal venous system are reported. The present study focused on the development of new tissue-engineered vascular graft using a silk-based scaffold material for abdominal venous system replacement. A rat vein, the inferior vena cava, was replaced by a silk fibroin (SF, a biocompatible natural insoluble protein present in silk thread), tissue-engineered vascular graft (10 mm long, 3 mm diameter, n = 19, SF group). The 1 and 4 -week patency rates and histologic reactions were compared with those of expanded polytetrafluoroethylene vascular grafts (n = 10, ePTFE group). The patency rate at 1 and 4 weeks after replacement in the SF group was 100.0% and 94.7%, and that in the ePTFE group was 100.0% and 80.0%, respectively. There was no significant difference between groups (p = 0.36). Unlike the ePTFE graft, CD31-positive endothelial cells covered the whole luminal surface of the SF vascular graft at 4 weeks, indicating better endothelialization. SF vascular grafts may be a promising tissue-engineered scaffold material for abdominal venous system replacement.

Biostable highly aligned polyurethane fibres for the potential application of small calibre vascular grafting

AbstractSynthetic vascular grafting is necessarily when the autografting is not possible in some cases. Conventional polyethylene terephthalate and expanded polytetrafluoroethylene vascular grafts are found to be effective for diameter bigger than 6 mm but not for the diameter smaller than 4 mm due to the compliance mismatch and thrombogenicity. Endothelization on the surface of the graft can reduce the risks of compliance mismatch and thrombogenicity. In order to catalyst the endothelization process, fibrous morphology similar to the extracellular matrix of our body is preferable in the vascular grafts. Apart from that, the biostability of the grafts is also an essential element to be considered as the biodegradation may reduce the efficiency of the grafts. Many polyurethanes have been recognised as biostable materials. Hence, in this study, highly aligned polyurethane fibres are fabricated using a facile dry spinning technique in the view of providing effective sites for endothelization process to occur. These fibres are immersed into the simulated body fluid for as long as 24 weeks before conducting the biostability characterisations. The biostability is assessed in three aspects, physical, mechanical and chemical properties. Results show that the fibres do not have observable or significant deteriorations in all the three aspects mentioned.

Preparation and characterization of a polyvinyl alcohol/polyacrylamide hydrogel vascular graft reinforced with a braided fiber stent

A PVA/PAAm (polyvinyl alcohol/polyacrylamide) hydrogel vascular graft reinforced by a braided fiber stent was prepared in the present work, and a series of characterizations were carried out for evaluating the comprehensive performance of the reinforced hydrogel vascular graft (RHVG), including the morphology, the mechanical properties and the biocompatibility. The results show that hydrogel with a mass ratio of 5:8 (PVA:PAAm) is the best candidate for developing an implantation-oriented vascular graft, whose overall performance is the closest to the requirements of clinical applications. The surface of the PVA/PAAm hydrogel is smooth, and the porous structure is uniform and stable. When the longitudinal strain of the RHVG was 50%, the tensile strength reached 905.6 ± 63.1 kPa, much higher than that of a swine common carotid artery (185 kPa). Moreover, the circumferential tensile strength was significantly enhanced by the integration of the stent, and the circumferential compression recovery reached 93.4 ± 6.7%, showing satisfactory structural stability. Furthermore, the suture retention force approached (9.89 ± 0.64 N), higher than that of a canine femoral artery (7.90 ± 0.36 N). More importantly, the radial dynamic compliance reached 3.11 ± 0.09% under testing pressure of 80–120 mmHg, which is 6.9 times that of a commercial expanded polytetrafluoroethylene vascular graft. Lastly, the RHVG has satisfying cytocompatibility and a low hemolysis rate. In summary, the present work may pave the way for developing a novel small-diameter vascular graft for clinical implantation.

Prevalence and risk factors for heparin-bonded expanded polytetrafluoroethylene vascular graft infection after infrainguinal femoropopliteal bypasses

BackgroundTo analyze the prevalence and predictors of prosthetic vascular graft infection (PVGI) in a multicenter registry. MethodsThis registry-based, multicenter study retrospectively evaluated PVGI that developed after infrainguinal revascularization performed with a heparin-bonded expanded polytetrafluoroethylene graft that was used in 1400 interventions between 2002 and 2016. A prosthetic graft with infection was defined as direct involvement of the graft with positive bacterial cultures of graft or perigraft material, intraoperative gross purulence or failure of graft incorporation, or exposed graft in an infected wound. ResultsCritical limb ischemia (CLI) was the main indication for bypass (n = 915 [65%]). The median duration of follow-up was 29 months (range, 1-168 months; interquartile range, 12-60 months). A total of 33 heparin-bonded expanded polytetrafluoroethylene grafts (2.3%) became infected; the median time to occurrence was 5 months (range, 1-54 months; interquartile range; 2.00-13.25 months). Freedom from PVGI at 1 year was 98% (standard error, 0.4; 95% confidence interval [CI], 97.2-98.9), and 97% (standard error, 0.6; 95% CI, 95.6-98.0) at 5 years. The multivariate model identified CLI (P = .042; hazard ratio, 0.39; 95% CI, 0.164-0.969) to be independently associated with PVGI. In-hospital mortality of PVGI treatment was 12% (n = 4/33). Freedom from major amputation was significantly different between patients with PVGI and those who did not experience this complication (at 1 year, 67.0% vs 88.5%; Log-rank χ2 = 22.5; P = .001). ConclusionsIn our “real-world” multicenter experience the prevalence of PVGI after infrainguinal femoropopliteal bypasses was relatively low at 2.3%, but still associated with significant mortality and limb loss. CLI was the only significant predictor of PVGI. This conclusion is reasonable; however, more comprehensive data are required to confirm these findings, because the presence of ischemic ulcers or gangrene was not predictive of PVGI.

Plasma Ion Activated Expanded Polytetrafluoroethylene Vascular Grafts with a Covalently Immobilized Recombinant Human Tropoelastin Coating Reducing Neointimal Hyperplasia.

Expanded polytetrafluoroethylene (ePTFE) vascular conduits with less than or equal to 6 mm internal diameter typically occlude due to a combination of thrombus formation and neointimal hyperplasia. We hypothesized that by layering the polymerized elastin precursor, human tropoelastin, in the synthetic vessel lumen we could mimic the internal elastic lamina and so maintain low thrombogenicity while significantly reducing smooth muscle cell proliferation. The luminal surfaces of ePTFE conduits were activated with plasma immersion ion implantation (PIII) treatment to facilitate covalent attachment of tropoelastin. Multilayered tropoelastin vessels (2TE) enhanced endothelial cell attachment and proliferation in vitro and were superior to materials lacking the protein. In an ovine carotid interposition model of graft compatibility, partially tropoelastin coated vessels (1TE) thrombosed at a greater rate than control ePTFE, but 2TE maintained the same patency as controls. 2TE showed a significant reduction in neointimal area down to 9.7 ± 5.2% (p < 0.05) in contrast to 32.3 ± 3.9% for ePTFE alone. This reduction was due to a halving of the number of smooth muscle cells present and a corresponding reduction in their proliferation. 2TE, but not 1TE, enhanced the vascular compatibility of these materials: while both tropoelastin presentations increased in vitro endothelialization, only 2TE displayed the dual benefits of maintained hemocompatibility and simultaneously suppressed neointimal hyperplasia in vivo. We conclude that 2TE surface modification provides a significant improvement over ePTFE vascular conduits in a pilot large animal model study and presents an attractive path toward clinical applications for reduced diameter vessels.

Invitro hemocompatibility and cytocompatibility of a three-layered vascular scaffold fabricated by sequential electrospinning of PCL, collagen, and PLLA nanofibers.

Aiming to mimic a blood vessel structurally, morphologically, and mechanically, a sequential electrospinning technique using a small diameter mandrel collector was performed and a three-layered tubular scaffold composed of nanofibers of polycaprolactone, collagen, and poly(l-lactic acid) as inner, intermediate, and outer layers, respectively, was developed. Biological performances of the scaffold in terms of compatibility with blood and endothelial cells were assessed to get some insights into its potential use as a tissue engineered small-diameter vascular replacement compared to an expanded polytetrafluoroethylene vascular graft. Due to direct contact of the blood and endothelial cells with inner surface of the scaffold, polycaprolactone fibers were characterized using SEM, water contact angle measurement, and ATR-FTIR. Despite similar surface wettability of the electrospun scaffold and the expanded polytetrafluoroethylene graft, the three-layered scaffold significantly reduced platelet adhesion and hemolysis ratio compared to expanded polytetrafluoroethylene graft while comparable blood clotting profiles were observed for both electrospun scaffold and expanded polytetrafluoroethylene graft. However, inflammatory response to nanofibrous surface of the scaffold was reduced compared to expanded polytetrafluoroethylene graft. The electrospun scaffold also presented a significantly more supportive substrate for endothelialization than the expanded polytetrafluoroethylene graft. The results described herein suggested that the three-layered scaffold has superior biological properties compared to an expanded polytetrafluoroethylene graft for vascular tissue engineering.

Early Results of Heparin-bonded Expanded Polytetrafluoroethylene Vascular Graft for Femoropopliteal Bypasses

Early Results of Heparin-bonded Expanded Polytetrafluoroethylene Vascular Graft for Femoropopliteal Bypasses

Synthetic graft for reconstruction of middle hepatic vein tributaries in living-donor liver transplant.

In middle hepatic vein dominant livers, the anterior segment of the right lobe of the liver (segments V and VIII) drains mainly into the middle hepatic vein. In these donors, when right lobe grafts are procured without the middle hepatic vein, the graft may harbor large segment V and/or VIII veins that need reconstruction to avoid graft congestion and subsequent graft dysfunction. Draining these middle hepatic vein tributaries using autologous or cryopreserved vessels is a solution, despite the possible difficulties of their preparation. However, these vessels are not always available. Our objective was to evaluate the effectiveness and safety of using a synthetic vascular graft. Between January 2012 and October 2013, eighteen adult recipients underwent living-donor liver transplant using right lobe grafts without the middle hepatic vein at Dar Al Fouad Hospital, 6th of October City, Egypt. All grafts had a large tributary of the middle hepatic vein. Eight-mm ringed expanded polytetrafluoroethylene vascular grafts were used to drain 15 segment V vein tributaries and 3 segment VIII vein tributaries directly to the inferior vena cava. Follow-up was done using duplex ultrasound to evaluate the patency of the vascular graft and the liver congestion and the liver function tests including liver enzymes. Intraoperative Duplex ultrasound confirmed patency and absent segmental congestion in all 18 recipients. The vascular graft patency was 17/18 at 1 week (94.4%) and 15/18 at 1 month (83.3%). No recipients developed graft infection at 1 month. Synthetic vascular expanded polytetrafluoroethylene grafts could be used effectively and safely in middle hepatic vein tributary reconstruction to overcome the unavailability of autologous or cryopreserved vessel grafts or just to avoid the additional burden of recovering autologous grafts thus simplifying the procedure.

Descending Thoracic Aorto-bifemoral Bypass for Aortoiliac Occlusive Disease

Introduction: Complete obstruction of the abdominal aorta at the renal artery level is a difficult surgical problem. Methods: From August 2010 to January 2014, descending thoracic aorta to femoral artery bypass grafting was used to re-vascularize the lower limbs of the patients in our center. We analysedd our results Results: Primary indication was lack of a suitable site for aortic clamping. Average duration of surgery was 2.5-4.5 h, and blood loss was 100-400 mL. We use BARD®, IMPRA® expanded polytetrafluoroethylene vascular graft for thoraco-bifemoral bypass surgery. There was one mortality due to myocardial infarction. Major morbidities were graft occlusion in one patient that was managed by embolectomy and ascites in another patient, managed conservatively. Conclusion: Thoracic aorta to femoral artery bypass is a simple extra anatomic bypass technique, which can be used in case of difficulty to use abdominal aorta for lower limb re-vascularization.

Endothelial outgrowth cells regulate coagulation, platelet accumulation, and respond to tumor necrosis factor similar to carotid endothelial cells.

Endothelial cells (ECs) are central regulators of hemostasis, inflammation, and other vascular processes. ECs have been used to cover vascular graft materials in an attempt to improve the biological integration of the grafts with the surrounding tissue. Although EC seeded grafts demonstrated improved patency, the invasive nature of EC harvest has limited the clinical translation of this technique. Endothelial outgrowth cells (EOCs) can be derived from circulating endothelial progenitor cells, which are noninvasively isolated from a peripheral blood draw. Although EOCs have been presumed to regulate hemostasis and inflammation similarly to arterial ECs, there has been limited research that directly compares EOCs to arterial ECs, particularly using pairs of donor-matched cells. This study provides a multifaceted characterization of hemostasis regulation by baboon EOCs and carotid ECs, both in the presence and absence of an inflammatory stimulus, tumor necrosis factor α (TNFα). The expression of genes involved in thrombosis and inflammation was highly similar between ECs and EOCs at a basal state and following TNFα stimulation. ECs and EOCs activated similar levels of protein C and Factor X (FX) at a basal state. Following TNFα treatment, EOCs had less of an increase in tissue factor activity than ECs. Cell-seeded expanded polytetrafluoroethylene vascular grafts demonstrated no significant differences between ECs and EOCs in platelet accumulation or fibrinogen incorporation in a baboon femoral arteriovenous shunt loop. This work demonstrates that EOCs regulate thrombus formation and respond to an inflammatory stimulus similar to ECs, and supports utilizing EOCs as a source for an autologous endothelium in tissue engineering applications.

Adipose Stromal Vascular Fraction Cells Isolated Using an Automated Point of Care System Improve the Patency of Expanded Polytetrafluoroethylene Vascular Grafts

We evaluated the use of an automated, point-of-care instrument to derive canine adipose stromal vascular fraction cells, and the subsequent deposition of these cells onto the luminal surface of an expanded polytetrafluoroethylene (ePTFE) vascular graft for use as a bypass graft. The hypothesis evaluated was that an instrument requiring minimal user interface will provide a therapeutic dose of cells to improve the patency of synthetic vascular grafts in an autologous animal model of graft patency. The stromal vascular fraction (SVF) cells were isolated using an automated adipose tissue processing and cell isolation system and cells sodded onto the surface of an ePTFE vascular graft. Control grafts, used off-the-shelf without cell treatment were used as a control to assess patency effects. Each animal received a control, untreated graft implanted in one carotid artery, and the cell-treated graft implanted in the carotid artery on the contralateral side. The grafts were implanted for 6 months utilizing 12 animals. Results indicate a fully automated adipose tissue processing system will consistently produce functional autologous cells for immediate use in the operating room. Cell-sodded polymeric grafts exhibited improved patency compared to control grafts after 6 month implantation in the canine carotid artery model.

A tissue‐engineered aneurysm model for evaluation of endovascular devices

Endovascular stent grafts used for treatment of arterial aneurysms require preclinical testing for investigation of biological responses following implantation. The preclinical evaluation process related to the safety and efficacy of these devices is limited by the absence of an in vitro aneurysmal blood vessel equivalent capable of providing high-throughput, cost-effective assessments. With this in mind, the focus of this work was to develop an aneurysm model consisting of human blood vessel cells. To create aneurysmal scaffolds, expanded polytetrafluoroethylene vascular grafts were dilated utilizing an angioplasty balloon. Stromal vascular fraction cells isolated from human adipose tissue were integrated with the scaffolds, and luminal flow of nutrient medium was executed for 14 days in a vascular bioreactor. Following bioreactor perfusion, histology verified that a neointimal lining of human tissue had formed. Immunohistochemistry and scanning electron microscopy revealed a flow-contacting layer of smooth muscle cells, characterizing the model as a representation of neointimal formation in an injured or diseased vessel. This study has demonstrated the engineering of a vascular construct containing an aneurysmal dilation. A tissue-engineered aneurysm model could provide an alternative to current nonbiological in vitro aneurysm models and serve as a practical tool in the progression of new devices toward in vivo studies.

Evolution of anterior segment reconstruction after live donor adult liver transplantation: a single‐center experience

Controversy exists regarding the best method for venous outflow reconstruction after live donor liver transplantation using right lobe grafts. Some authors advocate routine inclusion of the middle hepatic vein with the graft, whereas others favor a more selective approach. In this report, we examine the evolution of our decision making and technique of selective anterior venous segment reconstruction during live donor adult liver transplantation performed in 226 recipients. We have developed a simplified back-bench procedure using sequential-composite anastomosis using various vascular conduits with syndactylization to the right hepatic vein creating a single large-outflow anastomosis in the recipient. Conduits used include iliac artery or vein allograft, recanalized umbilical vein, cryopreserved iliac artery allograft, and 6-mm synthetic expanded polytetrafluoroethylene vascular graft. This technique can be performed quickly, safely, and under cold storage conditions and results in excellent outcome while minimizing donor risk.

The modulation of platelet and endothelial cell adhesion to vascular graft materials by perlecan

Controlled neo-endothelialisation is critical to the patency of small diameter vascular grafts. Endothelialisation and platelet adhesion to purified endothelial cell-derived perlecan, the major heparan sulfate (HS) proteoglycan in basement membranes, were investigated using in vivo and in vitro assays. Expanded polytetrafluoroethylene (ePTFE) vascular grafts were coated with perlecan and tested in an ovine carotid interposition model for a period of 6 weeks and assessed using light and scanning microscopy. Enhanced endothelial cell growth and reduced platelet adhesion were observed on the perlecan coated grafts when compared to uncoated controls implanted in the same sheep ( n = 5). Perlecan was also found to stimulate endothelial cell proliferation in vitro over a period of 6 days in the presence of plasma proteins and fibroblastic growth factor 2 (FGF-2), however in the absence of FGF-2 endothelial cell growth could not be maintained during this period. Perlecan was found to be anti-adhesive for platelets, however after removal of the HS chains attached to perlecan, platelet adhesion and aggregation were supported. These results suggest a role for HS chains of perlecan in improving graft patency by selectively promoting endothelial cell proliferation while modulating platelet adhesion.

The Safety and Efficacy of a Paclitaxel-eluting Wrap for Preventing Peripheral Bypass Graft Stenosis: A 2-Year Controlled Randomized Prospective Clinical Study

To compare the safety and efficacy of a bioresorbable paclitaxel-eluting wrap implanted with a synthetic vascular graft (treatment) versus the graft implanted alone (control). Prospective, randomized, controlled, multicentre, 2-year clinical study conducted in adults scheduled to undergo femoropopliteal peripheral bypass surgery with a polytetrafluoroethylene (PTFE) graft. Hundred and nine subjects were randomized 2:1 to treatment or control. All subjects were implanted with a 6mm expanded PTFE vascular graft; in addition, treated subjects had a 2.5 cm x 4 cm paclitaxel-eluting wrap (1.6 microg/mm(2)) placed around the distal graft anastomosis. The overall incidence of adverse events was similar in both groups. Treated subjects required fewer limb amputations than controls (15.5% vs 18.4%) and time to amputation for those that required amputation was twice as long (153 days vs 76 days). Among diabetics, this effect was pronounced with 13.8% of treated subjects requiring limb amputations compared with 23.5% of controls. Over the course of study, the diameter at the distal graft anastomosis was greater in treated subjects than in controls (difference of 2.1mm at 2 yr, p=0.03). The paclitaxel-eluting wrap maintained graft patency at the distal anastomosis and was safe to use in patients who had received a peripheral bypass PTFE graft.