In-vivo evaluation of silk fibroin small-diameter vascular grafts: state of art of preclinical studies and animal models

Autologous vein and artery remains the first choice for vascular grafting procedures in small-diameter vessels such as coronary and lower limb districts. Unfortunately, these vessels are often found to be unsuitable in atherosclerotic patients due to the presence of calcifications or to insufficient size. Synthetic grafts composed of materials such as expanded polytetrafluoroethylene (ePTFE) are frequently employed as second choice, because of their widespread availability and success in the reconstruction of larger arteries. However, ePTFE grafts with small diameter are plagued by poor patency rates due to surface thrombogenicity and intimal hyperplasia, caused by the bioinertness of the synthetic material and aggravated by low flow conditions. Several bioresorbable and biodegradable polymers have been developed and tested to exploit such issues for their potential stimulation to endothelialization and cell infiltration. Among these, silk fibroin (SF) has shown promising pre-clinical results as material for small-diameter vascular grafts (SDVGs) because of its favorable mechanical and biological properties. A putative advantage in graft infection in comparison with synthetic materials is plausible, although it remains to be demonstrated. Our literature review will focus on the performance of SF-SDVGs in vivo, as evaluated by studies performing vascular anastomosis and interposition procedures, within small and large animal models and different arterial districts. Efficiency under conditions that more accurately mime the human body will provide encouraging evidence towards future clinical application

RR5. Surgical Treatment of Popliteal Aneurysms Using a Posterior Approach: Thirteen Years' Follow-up

OBJECTIVES : Long-term results of posterior approach (PA) for the treatment of popliteal artery aneurysms are lacking in the literature. We compared our results with this access with those from a standard medial approach over a 13-years\u2019 period. METHODS: Clinical data of all patients treated for a popliteal aneurysm between 2/1998 and 10/2011 were retrospectively reviewed and outcomes analyzed: Kaplan-Meier method with log-rank, chi2 and Wilcoxon test were employed for analysis. RESULTS : A total of 78 aneurysms were treated in 66 patients (65 men). Mean age was 68 years (range 48-96 years). Thirty-six aneurysms were asymptomatic (46%). Mean sac diameter was 2.9\ub11 cm. A PA was used in 43 cases (55%) and a medial approach (MA) in 35. All PA consisted in aneurysmectomy with an interposition graft with end to end anastomoses; among MA 25 interposition grafts and 10 bypass were performed. A PTFE graft was used mostly (57 cases). The two groups differed for age only (median 65.4 for PA vs. 72.9 for MA p=0.01). Five patients had an early thrombosis and required a Fogarty thrombectomy (2 PA and 3 MA, all PTFE grafts). Mortality rate at 30 days was 0%. One patient suffered a peroneal nerve lesion (permanent) and another one a major wound necrosis with tissue loss (both PA). There were no early amputations. Median follow-up was 58.8 months (range 5 days-166.7 months). Nine patients died during follow-up for unrelated causes. The 5-year primary and secondary patency rates were 58.9%\ub18,7% and 96.4%\ub13.5% respectively for PA, and 67.4%\ub110,4% and 81.3%\ub18,9% respectively for MA (p=0.41 for primary patency rate and 0.28 for secondary patency rate). Limb salvage was 100% and 93.3%\ub16.4% at 5 and 10 years respectively for PA and 91.5%\ub15.6% at both time points for MA (p=0.3). CONCLUSIONS : PA in our experience was burdened by a few more early complications compared to MA. However in the long term it provided results which compare favorably to MA. AUTHOR DISCLOSURES: I. Barbetta, Nothing to disclose; M. Carmo, Nothing to disclose; R. Dallatana, Nothing to disclose; G. Grava, Nothing to disclose; D. Mazzaccaro, Nothing to disclose; A. M. Settembrini, Nothing to disclose; P. Settembrini, Nothing to disclose

Silk Fibroin Vascular Graft: From Design to In Vitro and In Vivo Test

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Three-Layered Silk Fibroin Tubular Scaffold for the Repair and Regeneration of Small Caliber Blood Vessels: From Design to in vivo Pilot Tests

Silk fibroin (SF) is an eligible biomaterial for the development of small caliber vascular grafts for substitution, repair, and regeneration of blood vessels. This study presents the properties of a newly designed multi-layered SF tubular scaffold for vascular grafting (SilkGraf). The wall architecture consists of two electrospun layers (inner and outer) and an intermediate textile layer. The latter was designed to confer high mechanical performance and resistance on the device, while electrospun layers allow enhancing its biomimicry properties and host\u2019s tissues integration. In vitro cell interaction studies performed with adult Human Coronary Artery Endothelial Cells (HCAECs), Human Aortic Smooth Muscle Cells (HASMCs), and Human Aortic Adventitial Fibroblasts (HAAFs) demonstrated that the electrospun layers favor cell adhesion, survival, and growth. Once cultured in vitro on the SF scaffold the three cell types showed an active metabolism (consumption of glucose and glutamine, release of lactate), and proliferation for up to 20 days. HAAF cells grown on SF showed a significantly lower synthesis of type I procollagen than on polystyrene, meaning a lower fibrotic effect of the SF substrate. The cytokine and chemokine expression patterns were investigated to evaluate the cells\u2019 proliferative and pro-inflammatory attitude. Interestingly, no significant amounts of truly pro-inflammatory cytokines were secreted by any of the three cell types which exhibited a clearly proliferative profile. Good hemocompatibility was observed by complement activation, hemolysis, and hematology assays. Finally, the results of an in vivo preliminary pilot trial on minipig and sheep to assess the functional behavior of implanted SF-based vascular graft identified the sheep as the more apt animal model for next medium-to-long term preclinical trials

Are Endoleaks Type Ia Predictable?

Objectives Aortic proximal (type Ia) endoleak (EL) is one of the possible complications of endovascular aneurysm repair (EVAR) and usually needs a further reintervention. The aim of our study was to assess any preoperative factor which could predict the development of EL Ia and whether it is treatable through an endovascular approach. Methods Data of patients consecutively treated between January 2012 and December 2015 with EVAR for nonruptured abdominal aortic aneurysm (AAA) were retrospectively collected. For each patient, demographic and anatomical factors (sex, age, proximal aortic neck diameter, angulation and length, AAA diameter) and structural characteristics of different endograft (presence of barbs, free flow, and radial force) were analyzed and related to the development of EL Ia using JMP 5.1.2 software. Results We analyzed 190 patients (32 females [16.8%]; mean age, 75.7 years). The mean follow-up time was 19 months. Patients\u2019 mean AAA diameter was 55.9 mm (range, 30-130 mm). A late EL Ia developed in 13 patients (7%), with a mean time of development of 30%, radial force, and the presence of suprarenal free flow and barbs were not significantly associated to the development of EL Ia. Female sex, age >77 years and a neck length <21 mm were statistically significant (P = .01, P = .02, and P = .02, respectively). Conclusions Among factors analyzed, female sex, age >77 years, and a proximal neck <21 mm were significantly associated with the occurrence of late EL Ia

PS196. Ultrasonic Debridement for the Treatment of Infected Grafts

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