Patency Of Vascular Grafts Research Articles

Nonlinear Elasticity of Blood Vessels and Vascular Grafts.

The transplantation of vascular grafts has emerged as a prevailing approach to address vascular disorders. However, the development of small-diameter vascular grafts is still in progress, as they serve in a more complicated mechanical environment than their counterparts with larger diameters. The biocompatibility and functional characteristics of small-diameter vascular grafts have been well developed; however, mismatch in mechanical properties between the vascular grafts and native arteries has not been accomplished, which might facilitate the long-term patency of small-diameter vascular grafts. From a point of view in mechanics, mimicking the nonlinear elastic mechanical behavior exhibited by natural blood vessels might be the state-of-the-art in designing vascular grafts. This review centers on elucidating the nonlinear elastic behavior of natural blood vessels and vascular grafts. The biological functionality and limitations associated with as-reported vascular grafts are meticulously reviewed and the future trajectory for fabricating biomimetic small-diameter grafts is discussed. This review might provide a different insight from the traditional design and fabrication of artificial vascular grafts.

Histologic and genetic features of remodeling of tissue-engineered small-diameter vascular grafts: outcomes of six-month implantation in a sheep model

Surface modification of polymeric scaffolds with drugs to avoid thrombus formation and infection is a promising area in tissue engineering, which also makes it possible to accelerate the remodeling of such scaffolds and improve long-term patency.The objective of this paper is to study the histologic and genetic features of remodeling of tissue-engineered small-diameter vascular grafts (SDVGs) with antithrombogenic drug-coated and reinforced external scaffolds, implanted into a sheep carotid artery.Materials and methods. Poly(ε-caprolactone) (PCL) matrices, ∅4 mm in diameter, were fabricated via electrospinning, followed by creation of a reinforcing spiral PCL scaffold on their outer surface by extrusion. To prevent thrombus formation and infection, the fabricated grafts were modified with iloprost and cationic amphiphile by complexation through polyvinylpyrrolidone (PVP). The work was carried out to evaluate, by infrared spectroscopy, the formation of PVP-based coating, to study the physical and mechanical properties of the grafts in longitudinal and transverse directions, and to implant the vascular grafts (VGs) into a sheep carotid artery. To assess and control the patency of the implanted grafts, Doppler ultrasound was performed at days 1 and 5, then at 1, 3 and 6 months. The explanted samples were studied via histological and immunofluorescent analyses; gene expression profile was evaluated.Results. Ultrasound on days 1 and 5 after implantation showed the patency of vascular grafts to be 100%. At 1 month, the patency decreased to 83.3%; patency was 50% by the end of the implantation period (6 months), without aneurysm formation and detachment of the reinforcing scaffold. Histological and immunofluorescence studies of patent grafts showed the formation of a newly formed three-layer vascular tissue structure on their basis, without signs of inflammation and calcification. However, despite the structural similarity between the newly formed vascular tissue and the native tissue of a sheep carotid artery, analysis of the gene expression profile revealed some differences in terms of genetic profile: CNN and SNA12 expression levels in the neotissue decreased, and those of CTSB, TNFa, and TGFb increased.Conclusion. Modified polymeric vascular scaffolds showed good remodeling of the prosthetic wall, without aneurysm formation. The identified genetic differences between newly formed tissue and native tissue are logical in view of formation on the basis of the artificial polymeric scaffold. Further research on reinforced polymeric scaffolds will be aimed at improving the inner surface in order to improve their thromboresistance.

Tetramethylpyrazine-derived polyurethane for improved hemocompatibility and rapid endothelialization.

Thrombosis and intimal hyperplasia (IH) are the main factors affecting the long-term patency of small-diameter vascular grafts (SDVGs). Fabricating a confluent endothelial cell (EC) layer on surfaces with physiological elasticity to mimic vascular endothelium should be an effective strategy to prevent restenosis that is caused by thrombosis and IH. However, the vascular endothelialization process is time-consuming and always constrained by hemocompatibility of the vascular grafts, since excellent hemocompatibility could guarantee a sufficient time window for the endothelialization process. Tetramethylpyrazine (TMP)-derived polyurethane (PU) with improved hemocompatibility and accelerated endothelialization ability is synthesized by incorporating TMP moieties into PU backbones. Results show that TMP-contained PU films possess improved hemocompatibility by down-regulating platelet adhesion/activation and increasing the clotting time. Furthermore, the in vitro human umbilical vein endothelial cell (HUVEC) test demonstrates that the introduction of TMP can significantly promote HUVEC adhesion and proliferation, and thus accelerate luminal endothelialization of vascular grafts. Moreover, the TMP-containing PU films exhibit excellent biocompatibility especially for HUVECs, and their excellent, adjustable elasticity (1123%) guarantees compliance accommodation of vascular grafts. This newly synthesized TMP-containing material with multiple biological functions is expected to make up for the shortcomings of available SDVGs in clinical practice, and has significant potential in improving the long-term patency of SDVGs.

Fluid-structure interactions of peripheral arteries using a coupled in silico and in vitro approach

Vascular compliance is considered both a cause and a consequence of cardiovascular disease and a significant factor in the mid- and long-term patency of vascular grafts. However, the biomechanical effects of localised changes in compliance cannot be satisfactorily studied with the available medical imaging technologies or surgical simulation materials. To address this unmet need, we developed a coupled silico-vitro platform which allows for the validation of numerical fluid-structure interaction results as a numerical model and physical prototype. This numerical one-way and two-way fluid-structure interaction study is based on a three-dimensional computer model of an idealised femoral artery which is validated against patient measurements derived from the literature. The numerical results are then compared with experimental values collected from compliant arterial phantoms via direct pressurisation and ring tensile testing. Phantoms within a compliance range of 1.4–68.0%/100 mmHg were fabricated via additive manufacturing and silicone casting, then mechanically characterised via ring tensile testing and optical analysis under direct pressurisation with moderately statistically significant differences in measured compliance ranging between 10 and 20% for the two methods. One-way fluid-structure interaction coupling underestimated arterial wall compliance by up to 14.7% compared with two-way coupled models. Overall, Solaris™ (Smooth-On) matched the compliance range of the numerical and in vivo patient models most closely out of the tested silicone materials. Our approach is promising for vascular applications where mechanical compliance is especially important, such as the study of diseases which commonly affect arterial wall stiffness, such as atherosclerosis, and the model-based design, surgical training, and optimisation of vascular prostheses.

Incorporating Anticoagulant and Antiplatelet Dual Functional Groups into Thermosetting Polymer Chain for Enhancing Antithrombogenicity.

In clinical practice, high-effective antithrombosis remains a challenge for blood-contacting medical devices. Inspired by the enhanced antithrombogenicity of anticoagulant and antiplatelet combination therapy, a strategy is proposed to synthesize dual-pathway antithrombotic polymers by incorporating anticoagulant and antiplatelet dual functional groups into a single thermosetting polymer chain. The synthesized polymer shows increased antithrombogenicity in vitro, with prolonged activated partial thromboplastin time (APTT) and decreased platelet adhesion. Additionally, it downregulates the expression of coagulation- and inflammation-related factors in rabbit plasma after ex vivo arteriovenous shunt assay and maintains patency of small vascular grafts for at least 6 months without thrombosis on the luminal surface after invivoreplacement of rabbit carotid artery. Thiswork provides a new approach to producing novel antithrombotic polymers for blood-contacting medical devices.

Functionalization of in vivo tissue-engineered living biotubes enhance patency and endothelization without the requirement of systemic anticoagulant administration.

Vascular regeneration and patency maintenance, without anticoagulant administration, represent key developmental trends to enhance small-diameter vascular grafts (SDVG) performance. In vivo engineered autologous biotubes have emerged as SDVG candidates with pro-regenerative properties. However, mechanical failure coupled with thrombus formation hinder translational prospects of biotubes as SDVGs. Previously fabricated poly(ε-caprolactone) skeleton-reinforced biotubes (PBs) circumvented mechanical issues and achieved vascular regeneration, but orally administered anticoagulants were required. Here, highly efficient and biocompatible functional modifications were introduced to living cells on PB lumens. The 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-methoxy (DMPE)-PEG-conjugated anti-coagulant bivalirudin (DPB) and DMPE-PEG-conjugated endothelial progenitor cell (EPC)-binding TPS-peptide (DPT) modifications possessed functionality conducive to promoting vascular graft patency. Co-modification of DPB and DPT swiftly attained luminal saturation without influencing cell viability. DPB repellent of non-specific proteins, DPB inhibition of thrombus formation, and DPB protection against functional masking of DPT's EPC-capture by blood components, which promoted patency and rapid endothelialization in rat and canine artery implantation models without anticoagulant administration. This strategy offers a safe, facile, and fast technical approach to convey additional functionalization to living cells within tissue-engineered constructs.

Bioinspired, Anticoagulative, 19 F MRI-Visualizable Bilayer Hydrogel Tubes as High Patency Small-Diameter Vascular Grafts.

The clinical patency of small-diameter vascular grafts (SDVGs) (ID < 6mm) is limited, with the formation of mural thrombi being a major threat of this limitation. Herein, a bilayered hydrogel tube based on the essential structure of native blood vessels isdeveloped by optimizing the relation between vascular functions and the molecular structure of hydrogels. The inner layer of the SDVGs comprises a zwitterionic fluorinated hydrogel, avoiding the formation of thromboinflammation-induced mural thrombi. Furthermore, the position and morphology of the SDVGs canbe visualized via 19 F/1 H magnetic resonance imaging. The outer poly(N-acryloyl glycinamide) hydrogel layer of SDVGs provides matched mechanical properties with native blood vessels through the multiple and controllable intermolecular hydrogen-bond interactions, which canwithstand the accelerated fatigue test under pulsatile radial pressure for 380 million cycles (equal to a service life of 10 years in vivo). Consequently, the SDVGs exhibit higher patency (100%) and more stable morphology following porcine carotid artery transplantation for 9 months and rabbit carotid artery transplantation for 3 months. Therefore, such a bioinspired, antithrombotic, and visualizable SDVG presents a promising design approach for long-term patency products and great potential of helping patients with cardiovascular diseases.

Effects of Cyclic Peptide LXW7 Coating on Short-term Vascular Graft Patency Using a Porcine (Sus scrofa) Model

We previously identified LXW7, a specific integrin αvβ3 targeting ligand capable of selectively capturing endothelial progenitor cells and endothelial cells, and developed a parylene-based conformal coating technology to covalently present LXW7 to prosthetic materials. In previous in vitro and in vivo studies, LXW7-coated grafts have demonstrated successful capture of endothelial progenitor cells and endothelial cells, which then promotes re-endothelialization of these prosthetic materials. This study aims to assess the function of LXW7 coating on interposition expanded polytetrafluoroethylene (ePTFE) graft thrombus formation and patency in a large animal model. Eight female Yorkshire pigs underwent transperitoneal implantation of bilateral iliac artery interposition bypasses using control plain ePTFE grafts (inner diameter 6 mm) and LXW7-coated ePTFE grafts. Each animal served as its own control and the implanting surgeon and experimental team were blinded to treatment and evaluations. The animals underwent computed tomography angiography (CTA) immediately postoperatively and at 3 and 6 weeks postimplantation. After final CTA imaging, animals were sacrificed and interposition grafts were harvested for histological evaluation. The project proceeded following the approval of United States Air Force, David Grant Medical Center Institutional Animal Care and Use Committee. Six animals were included in final analysis, with two excluded due to complications during their surgical and postoperative course requiring euthanasia. Average native artery diameter was 4.08 mm for the control grafts and 4.17 mm for LXW7-coated grafts (P = .296). Average clamp time was similar between groups (60 minutes for the control grafts vs 52 minutes on the LXW7-coated grafts; P = .291). The immediate postprocedure CTA demonstrated procedural success for all six pigs with no evidence of thrombus or stenosis. At the 3-week imaging, all grafts remained patent. At the 6-week imaging, all six LXW7-coated grafts were patent without evidence of thrombus or stenosis while four of the six control grafts were either fully or partially thrombosed. Repeated measures mixed effects analysis demonstrated significantly improved patency over time with LXW7 coated grafts (P < .001) (Figure). This is the first study using CTA to investigate the impact of LXW7 coating on prosthetic vascular graft patency in a clinically relevant large animal model. The findings demonstrate significantly improved graft patency over time with use of LXW7 coating, suggesting promise as a potential adjunct to clinical outcomes with prosthetic grafts in vascular bypass applications.Fig 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Endothelium-Mimetic Surface Modification Improves Antithrombogenicity and Enhances Patency of Vascular Grafts in Rats and Pigs

We first identified thrombomodulin (TM) and endothelial nitric oxide (NO) synthase as key factors for the antithrombogenic function of the endothelium in human atherosclerotic carotid arteries. Then, recombinant TM and an engineered galactosidase responsible for the conversion of an exogenous NO prodrug were immobilized on the surface of the vascular grafts. Surface modification by TM and NO cooperatively enhanced the antithrombogenicity and patency of vascular grafts. Importantly, we found that the combination of TM and NO also promoted endothelialization, whereas it reduced adverse intimal hyperplasia, which is critical for the maintenance of vascular homeostasis, as confirmed in rat and pig models.

Peritoneal pre-conditioning impacts long-term vascular graft patency and remodeling.

There are questions about how well small-animal models for tissue-engineered vascular grafts (TEVGs) translate to clinical patients. Most TEVG studies used grafting times ≤6months where conduits from generally biocompatible materials like poly(ε-caprolactone) (PCL) perform well. However, longer grafting times can result in significant intimal hyperplasia and calcification. This study tests the hypothesis that differences in pro-inflammatory response from pure PCL conduits will be consequential after long-term grafting. It also tests the long-term benefits of a peritoneal pre-implantation strategy on rodent outcomes. Electrospun conduits with and without peritoneal pre-implantation, and with 0% and 10% (w/w) collagen/PCL, were grafted into abdominal aortae of rats for 10months. This study found that viability of control grafts without pre-implantation was reduced unlike prior studies with shorter grafting times, confirming the relevance of this model. Importantly, pre-implanted grafts had a 100% patency rate. Further, pre-implantation reduced intimal hyperplasia within the graft. Differences in response between pure PCL and collagen/PCL conduits were observed (e.g., fewer CD80+ and CD3+ cells for collagen/PCL), but only pre-implantation had an effect on the overall graft viability. This study demonstrates how long-term grafting in rodent models can better evaluate viability of different TEVGs, and the benefits of the peritoneal pre-implantation step.

Abstract 601: Effects Of Cyclic Peptide Lxw7 Coating On Short Term Vascular Graft Patency Using A Porcine ( Sus Scrofa) Model

Introduction: We previously identified LXW7, a specific integrin αvβ3 targeting ligand capable of selectively capturing endothelial progenitor cells (EPCs) and endothelial cells (ECs), and developed a parylene-based conformal coating technology to covalently bind LXW7 to prosthetic materials. LXW7-coated grafts have demonstrated successful capture of EPCs and ECs, which then promotes endothelialization of prosthetic materials. This study aims to assess the function of LXW7 coating on interposition polytetrafluoroethylene (ePTFE) graft thrombus formation and patency in a large animal model. Methods: 8 Yorkshire pigs underwent implantation of bilateral iliac artery interposition bypasses using control ePTFE grafts and LXW7-coated ePTFE grafts. Each animal served as its own control and the implanting surgeon and experimental team were blinded to treatment and evaluations. Computed Tomography Angiogram (CTA) immediately post-operatively, 3 weeks, and 6 weeks post-implantation. After final CTA, animals were sacrificed and grafts were harvested. The project proceeded following the approval of United States Air Force, David Grant Medical Center Institutional Animal Care &amp; Use Committee. Results: 6 animals were included in final analysis, with 2 excluded due to complications during their surgical and post-operative course requiring euthanasia. Native artery diameter was 4.08mm for the control grafts and 4.17mm for LXW7-coated grafts (p=0.296). Post-procedure CTA demonstrated procedural success for all 6 pigs with no evidence of thrombus or stenosis. At 3 week imaging, all grafts remained patent. 6 week imaging, all LXW7-coated grafts were patent without evidence of thrombus or stenosis while 4 of the 6 control grafts were either fully or partially thrombosed. Repeated measures mixed effects analysis demonstrated significantly improved patency over time with LXW7 coated grafts (p&lt;0.001). Conclusion: This is the first study investigating LXW7-coating on prosthetic vascular graft patency in a large animal model. We demonstrate significantly improved graft patency use of LXW7-coating, suggesting promise as an adjunct for prosthetic grafts in vascular bypass applications.

Prevention of anastomotic stenosis for decellularized vascular grafts using rapamycin-loaded boronic acid-based hydrogels mimicking the perivascular tissue function

Abnormal proliferation of vascular smooth muscle cells (VSMCs) induces graft anastomotic stenosis, resulting in graft failure. Herein, we developed a drug-loaded tissue-adhesive hydrogel as artificial perivascular tissue to suppress VSMCs proliferation. Rapamycin (RPM), an anti-stenosis drug, is selected as the drug model. The hydrogel was composed of poly (3-acrylamidophenylboronic acid-co-acrylamide) (BAAm) and polyvinyl alcohol. Since phenylboronic acid reportedly binds to sialic acid of glycoproteins which is distributed on the tissues, the hydrogel is expected to be adherent to the vascular adventitia. Two hydrogels containing 25 or 50 mg/mL of BAAm (BAVA25 and BAVA50, respectively) were prepared. A decellularized vascular graft with a diameter of <2.5 mm was selected as a graft model. Lap-shear test indicates that both hydrogels adhered to the graft adventitia. In vitro release test indicated that 83 and 73 % of RPM in BAVA25 and BAVA50 hydrogels was released after 24 h, respectively. When VSMCs were cultured with RPM-loaded BAVA hydrogels, their proliferation was suppressed at an earlier stage in RPM-loaded BAVA25 hydrogels compared to RPM-loaded BAVA50 hydrogels. An in vivo preliminary test reveals that the graft coated with RPM-loaded BAVA25 hydrogel shows better graft patency for at least 180 d than the graft coated with RPM-loaded BAVA50 hydrogel or without hydrogel. Our results suggest that RPM-loaded BAVA25 hydrogel with tissue adhesive characteristics has potential to improve decellularized vascular graft patency.

Multifunctional nanoparticle-VEGF modification for tissue-engineered vascular graft to promote sustained anti-thrombosis and rapid endothelialization.

Purpose: The absence of a complete endothelial cell layer is a well-recognized reason leading to small-diameter tissue-engineered vascular graft failure. Here we reported a multifunctional system consisting of chitosan (CS), Arg-Glu-Asp-Val (REDV) peptide, heparin, and vascular endothelial growth factor (VEGF) to achieve sustained anti-thrombosis and rapid endothelialization for decellularized and photo-oxidized bovine internal mammary arteries (DP-BIMA). Methods: CS-REDV copolymers were synthesized via a transglutaminase (TGase) catalyzed reaction. CS-REDV-Hep nanoparticles were formed by electrostatic self-assembly and loaded on the DP-BIMA. The quantification of released heparin and vascular endothelial growth factor was detected. Hemolysis rate, platelets adhesion, endothelial cell (EC) adhesion and proliferation, and MTT assay were performed in vitro. The grafts were then tested in a rabbit abdominal aorta interposition model for 3months. The patency rates were calculated and the ECs regeneration was investigated by immunofluorescence staining of CD31, CD144, and eNOS antibodies. Results: The nanoparticle-VEGF system (particle size: 61.8 ± 18.3nm, zeta-potential: +13.2mV, PDI: .108) showed a sustained and controlled release of heparin and VEGF for as long as 1month and exhibited good biocompatibility, a lower affinity for platelets, and a higher affinity for ECs in vitro. The nanoparticle-VEGF immobilized BIMA achieved 100% and 83.3% patency in a rabbit abdominal interposition model during 1 and 3months, respectively, without any thrombogenicity and showed CD31, CD144, eNOS positive cell adhesion as early as 1day. After 3months, CD31, CD144, and eNOS positive cells covered almost the whole luminal surface of the grafts. Conclusion: The results demonstrated that the multifunctional nanoparticle-VEGF system can enhance the anti-thrombosis property and promote rapid endothelialization of small-diameter tissue-engineered vascular grafts. Utilizing nanoparticles to combine different kinds of biomolecules is an appropriate technology to improve the long-term patency of small-diameter tissue-engineered vascular grafts.

Surface modification with hydrophilic and heparin-loaded coating for endothelialization and anticoagulation promotion of vascular scaffold

Surface modifications are common approaches to promote endothelialization and resist thrombus, therefore obtaining long-term patency of vascular grafts. Herein, we developed a functional coating based on hyaluronic acid (HA), dopamine (DA), and heparin. In the present study, dopamine was firstly grafted to the HA molecules. The DA-grafted HA material was then applied to the surface of fibrous PCL scaffold via oxidation polymerization. Heparin was directly loaded during the coating, instead of grafting. The composite coating enhanced the surface hydrophilicity of PCL scaffold, as well as the mechanical properties. Notably, the coated scaffold could promote EC proliferation and angiogenesis behavior via the upregulation of CD31 gene expression regardless of heparin addition. It also showed more effective inhibition of platelet adhesion and blood clotting in vitro. These results lead us to the conclusion that this functional coating is great potential in treating cardiovascular diseases in terms of promoting endothelialization, reducing thrombus, and maintaining the long-term patency of vascular grafts.

Polyvinyl alcohol coating prevents platelet adsorption and improves mechanical property of polycaprolactone-based small-caliber vascular graft.

The low patency of synthetic vascular grafts hinders their practical applicability. Polyvinyl alcohol (PVA) is a non-toxic, highly hydrophilic polymer; thus, we created a PVA-coated polycaprolactone (PCL) nanofiber vascular graft (PVA–PCL graft). In this study, we examine whether PVA could improve the hydrophilicity of PCL grafts and evaluate its in vivo performance using a rat aorta implantation model. A PCL graft with an inner diameter of 1 mm is created using electrospinning (control). The PCL nanofibers are coated with PVA, resulting in a PVA–PCL graft. Mechanical property tests demonstrate that the PVA coating significantly increases the stiffness and resilience of the PCL graft. The PVA–PCL surface exhibits a much smaller sessile drop contact angle when compared with that of the control, indicating that the PVA coating has hydrophilic properties. Additionally, the PVA–PCL graft shows significantly less platelet adsorption than the control. The proposed PVA–PCL graft is implanted into the rat’s abdominal aorta, and its in vivo performance is tested at 8 weeks. The patency rate is 83.3% (10/12). The histological analysis demonstrates autologous cell engraftment on and inside the scaffold, as well as CD31/α-smooth muscle positive neointima regeneration on the graft lumen. Thus, the PVA–PCL grafts exhibit biocompatibility in the rat model, which suggests that the PVA coating is a promising approach for functionalizing PCL.

Programming of Regulatory T Cells In Situ for Nerve Regeneration and Long-Term Patency of Vascular Grafts.

Rapid integration into the host tissue is critical for long-term patency after small diameter tissue engineering vascular grafts (sdTEVGs) transplantation. Neural recognition may be required for host integration and functionalization of the graft. However, immune rejection and inflammation hinder nerve regeneration of sdTEVGs. Here, a CRISPR/dCas9-nanocarrier was used for targeted programming of regulatory T cells (Treg cells) in situ to promote nerve regeneration of sdTEVGs by preventing excessive inflammation. Treg cells and (C-C chemokine receptor) CCR2+ macrophage recruitment occurred after transplantation. The nanodelivery system upregulated ten eleven translocation (TET2) in Treg cells in vitro. Reprogrammed Treg cells upregulated anti-inflammatory cytokines and decreased the proportion of CCR2+ macrophages. IL-6 concentrations decreased to the levels required for nerve regeneration. Implantation of CRISPR/dCas9 nanodelivery system-modified sdTEVGs in rats resulted in Treg cell editing, control of excessive inflammation, and promoted nerve regeneration. After 3 months, nerve regeneration was similar to that observed in normal blood vessels; good immune homeostasis, consistency of hemodynamics, and matrix regeneration were observed. Neural recognition promotes further integration of the graft into the host, with unobstructed blood vessels without intimal hyperplasia. Our findings provide new insights into vascular implant functionalization by the host.

Modulation of neo-endothelialization of vascular graft materials by silk fibroin.

Controlled neo-endothelialization is critical to the patency of vascular grafts. Expanded polyethylene terephthalate (PET) vascular grafts were grafted with polyethylene glycol (PEG), irradiated with ultraviolet light, and subsequently coated with silk fibroin (SF) and EDC in a dip-coating process. Endothelial cells were cultivated on the coated samples for 1, 3, 5, and 7days, and characterized by fluorescence microscopy and scanning electron microscopy (SEM). The quantitative analyse of CCK-8 method was used to assess ECs proliferation. The results reveal the correlation between grafting components and cell adhesion. We demonstrated that PET with SF grafting facilitated cell adhesion and spreading. Following 7days of cell culture in vitro, PET-PEG6000-SF (PEG molecular weight 6,000) displayed spreading of cells over a significantly larger area. Rapid endothelialization on a modified PET surface resulted in large tissue pack that can be observed by SEM.

Surgical and oncologic outcomes following arterial resection and reconstruction for advanced solid tumors.

Although arterial involvement for advanced tumors is rare, vascular resection may be indicated to achieve complete tumor resection. Given the potential morbidity of this approach, we sought to evaluate perioperative outcomes, vascular graft patency, and survival among patients undergoing tumor excision with en bloc arterial resection and reconstruction. From 2010 to 2020, we identified nine patients with tumors encasing or extensively abutting major arterial structures for whom en bloc arterial resection and reconstruction was performed. Mean age was 53 ± 20 years, and 89% were females. Diagnoses were primary sarcomas (5), recurrent gynecologic carcinomas (3), and benign retroperitoneal fibrosis (1). Tumors involved the infrarenal aorta (2), iliac arteries (6), and superficial femoral artery (1). Three patients (33%) had severe perioperative morbidity (Grade III + ) with no mortality. At a median follow-up of 23 months, eight patients (89%) had primary graft patency, and five patients (56%) had no evidence of disease. Arterial resection and reconstruction as part of the multimodality treatment of regionally advanced tumors is associated with acceptable short- and long-term outcomes, including excellent graft patency. In appropriately selected patients, involvement of major arterial structures should not be viewed as a contraindication to attempted curative surgery.

The prescription of best medical therapy following infrainguinal bypass grafting in Australia and New Zealand: a multicentre Australasian audit.

The benefits of best medical therapy (BMT) for secondary prevention of cardiovascular events in patients with peripheral arterial disease are well established. Guidelines recommend prescription of BMT should consist of anti-platelet, statins and angiotensin-converting enzyme inhibitor or angiotensin receptor blocking therapy, with evidence this regimen reduces cardiovascular mortality following vascular surgery and improves vascular bypass graft patency. This multicentre study examines the BMT prescription on discharge after infrainguinal bypass (IIB) in Australia and New Zealand (ANZ). Primary outcome measure was discharge prescription of three BMT pharmacological agents, defined for study purposes as an anti-platelet/anti-coagulant, a lipid-lowering agent, and an anti-hypertensive medication if hypertension was diagnosed. This study retrospectively examined discharge prescriptions and summaries of all patients discharged following IIB in five ANZ hospitals, between January 2015 and April 2018. A total of 688 admissions for IIB were included (76.9% male; mean age 67.8 ± 12.0). A total of 72.4% of procedures were for chronic limb ischaemia, compared to acute limb ischaemia (12.6%), and aneurysmal disease (15%). The primary outcome of adherence with complete BMT prescription occurred in 66.9% of admissions. Anti-thrombotic agents were most frequently prescribed (96.4%), followed by anti-lipidaemic agents (82.1%). Of the patients with documented hypertension, 43.8% were not prescribed an angiotensin-converting enzyme inhibitor/angiotensin receptor blocking, while 19.2% were discharged without any anti-hypertensive medications. Almost one third of patients were not prescribed complete BMT following IIB. There is potential to improve the outcomes after IIB in ANZ through a focus on risk-factor control and BMT prescription.

Outcomes of Sarcoma Resections Requiring Vascular Surgical Assistance: A Single-Center Experience.

Objective: To describe the types of intervention and determine patency and survival after arterial and venous reconstruction after surgical excision of sarcomas. Methods: Between November 2001 and July 2015, 42 patients with sarcomas and vascular involvement underwent surgical oncologic resection followed by arterial or venous reconstruction or preservation of the native vascular bundle. Univariate, multivariate, and Kaplan-Meier survival analyses were performed on abstracted data, which included demographics, risk factors, oncologic and vascular treatment modalities, postoperative complications, graft patency, and survival outcomes. Results: A total of 42 sarcomas required vascular assistance for oncologic removal. The majority of sarcomas were malignant fibrous histiocytoma (23.8%), and the most common anatomic location was the retroperitoneum (48%). A total of 12 revascularizations procedures were performed, including 5 arterial, 3 venous, and 2 concomitant arterial and venous. In 32 cases, a vascular surgeon was needed for vessel ligation, repair, or mobilization. The overall 2- and 5-year survival was 77.7% and 26.2%, respectively, with no significant survival difference between patients who underwent revascularization compared to those without revascularization. There was a 100% patency rate in all cases at last follow-up, regardless of the type of vascular reconstruction (median 18 months, range 1-29 months). On multivariate analysis, chronic obstructive pulmonary disease (COPD; P = .002) and positive surgical margins (P = .003) were associated with decreased survival. Most cases were performed in the last 5 years of the study (n = 27, 64.3%). Conclusions: Vascular reconstruction is feasible after surgical oncologic resection of sarcomas with good mid-term patency and limb preservation. Factors independently associated with mortality included COPD and positive surgical margins.