Zuojun Hu

The Preparation and Performance of a New Polyurethane Vascular Prosthesis

We investigated the performance of small-caliber polyurethane (PU) small-diameter vascular prosthesis generated using the electrospinning technique. PU was electrospun into small-diameter, small-caliber tubular scaffolds for potential application as vascular grafts. We investigated the effects of electrospinning conditions (solution concentration, mandrel rotation speed) on the microstructure and porosity of the scaffolds for the purpose of preparing scaffolds with optimum microstructures and properties. We evaluated the mechanical properties of the scaffolds by tensile tests and the cytotoxicity of the PU small-diameter, small-caliber PU synthetic vascular graft by the MTT assay. The adhesion of endothelial cells to the PU scaffold was characterized by Hoechst staining and fluorescence microscopy, and we measured endothelial cell proliferation on the PU scaffold by the CCK-8 assay. We analyzed the prosthesis microstructure and endothelial cell morphology using scanning electron microscopy. With increasing PU concentration in the electrospinning solution, the fiber diameter of the vascular graft increased and the porosity decreased. In addition, with increasing electrospinning time, the wall thickness increased and the porosity decreased. We found that regular fiber orientation can be obtained by adjusting the rotation speed of the mandrel. Cell proliferation was not inhibited as the small-caliber PU synthetic vascular grafts showed little cytotoxicity. The endothelial cells had faster adherence to the PU scaffolds than to the PTFE surface during the initial contact. After prolonged cell culture, significantly higher endothelial cell proliferation rate was observed in the PU scaffold groups than the PTFE group. We obtained small-caliber PU vascular grafts with optimal fiber arrangement, excellent mechanical properties, and optimal biocompatibility by optimizing the electrospinning conditions. This study provides in vitro biocompatibility data that is helpful for the clinical application of the PU small-diameter, small-caliber PU vascular grafts.

Endovascular treatment of arch and proximal thoracic aortic lesions.

OBJECTIVE To analyze at one institution the endovascular treatment for aortic arch and proximal thoracic aortic lesions, categorize open arch reconstruction, and make preliminary recommendations based on pathology (dissection vs aneurysm), and anatomical extent of disease. METHODS A retrospective review of aortic arch and descending thoracic aortic lesions managed with endovascular treatment between June 2002 and June 2007. RESULTS Thirty-four patients received endovascular repair for aortic dissection (n = 28) and aneurysm (n = 6). Open supra-aortic transposition or debranching of the great vessels was performed in 14 cases of dissection (50%) and six cases (100%) of aneurysm. In 14 dissections, the entry tear was located in the distal aortic arch, enabling the left subclavian artery to be sealed without reconstruction. The procedures were successful in 33 patients (97.1%); one intraoperative death occurred. Type I endoleaks were found intraoperatively in eight cases. After management with balloon angioplasty and by extending the stent implantation, the endoleaks resolved in four cases and decreased in four cases. One patient with Stanford type A dissection died from an unknown cause 3 months after treatment. The overall survival rate was 94.1% (32/34), and all bypass grafts remained patent during the follow-up period. CONCLUSIONS Endovascular stent grafting is a safe and effective method for the treatment of aortic arch lesions. Transposition of the supra-aortic great vessels can be effectively combined with endovascular stent grafting to ensure both cerebral blood supply and enough landing area for the stent graft.

A novel dendritic nanocarrier of polyamidoamine-polyethylene glycol-cyclic RGD for “smart” small interfering RNA delivery and in vitro antitumor effects by human ether-à-go-go-related gene silencing in anaplastic thyroid carcinoma cells

The application of RNA interference techniques is promising in gene therapeutic approaches, especially for cancers. To improve safety and efficiency of small interfering RNA (siRNA) delivery, a triblock dendritic nanocarrier, polyamidoamine-polyethylene glycol-cyclic RGD (PAMAM-PEG-cRGD), was developed and studied as an siRNA vector targeting the human ether-à-go-go-related gene (hERG) in human anaplastic thyroid carcinoma cells. Structure characterization, particle size, zeta potential, and gel retardation assay confirmed that complete triblock components were successfully synthesized with effective binding capacity of siRNA in this triblock nanocarrier. Cytotoxicity data indicated that conjugation of PEG significantly alleviated cytotoxicity when compared with unmodified PAMAM. PAMAM-PEG-cRGD exerted potent siRNA cellular internalization in which transfection efficiency measured by flow cytometry was up to 68% when the charge ratio (N/P ratio) was 3.5. Ligand-receptor affinity together with electrostatic interaction should be involved in the nano-siRNA endocytosis mechanism and we then proved that attachment of cRGD enhanced cellular uptake via RGD-integrin recognition. Gene silencing was evaluated by reverse transcription polymerase chain reaction and PAMAM-PEG-cRGD-siRNA complex downregulated the expression of hERG to 26.3% of the control value. Furthermore, gene knockdown of hERG elicited growth suppression as well as activated apoptosis by means of abolishing vascular endothelial growth factor secretion and triggering caspase-3 cascade in anaplastic thyroid carcinoma cells. Our study demonstrates that this novel triblock polymer, PAMAM-PEG-cRGD, exhibits negligible cytotoxicity, effective transfection, “smart” cancer targeting, and therefore is a promising siRNA nanocarrier.

The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts.

BackgroundIn a previous in vitro study, we confirmed that small-caliber nanofibrous polyurethane (PU) vascular grafts have favorable mechanical properties and biocompatibility. In the present study, we examined the in vivo biocompatibility and stability of these grafts.MethodsForty-eight adult male beagle dogs were randomly divided into two groups receiving, respectively, polyurethane (PU) or polytetrafluoroethylene (PTFE) grafts (n = 24 animals / group). Each group was studied at 4, 8, 12, and 24 weeks after graft implantation. Blood flow was analyzed by color Doppler ultrasound and computed tomography angiography. Patency rates were judged by animal survival rates. Coverage with endothelial and smooth muscle cells was characterized by hematoxylin-eosin and immunohistological staining, and scanning electron microscopy (SEM).ResultsPatency rates were significantly higher in the PU group (p = 0.02 vs. PTFE group). During the first 8 weeks, endothelial cells gradually formed a continuous layer on the internal surface of PU grafts, whereas coverage of PTFE graft by endothelial cells was inhomogeneous. After 12 weeks, neointimal thickness remained constant in the PU group, while PTFE group showed neointimal hyperplasia. At 24 weeks, some anastomotic sites of PTFE grafts became stenotic (p = 0.013 vs. PU group). Immunohistological staining revealed a continuous coverage by endothelial cells and an orderly arrangement of smooth muscle cells on PU grafts. Further, SEM showed smooth internal surfaces in PU grafts without thrombus or obvious neointimal hyperplasia.ConclusionsSmall-caliber nanofibrous PU vascular grafts facilitate the endothelialization process, prevent excessive neointimal hyperplasia, and improve patency rates.

Tolerable Hemodynamic Changes after Femoral Artery Ligation for the Treatment of Infected Femoral Artery Pseudoaneurysm

BACKGROUND We analyzed the hemodynamic changes induced by femoral artery ligation with concomitant thrombectomy in intravenous drug abusers with infected femoral artery pseudoaneurysm (IFAP) and their clinical significance. METHODS Between January 2000 and November 2007, a total of 55 patients presented to our clinic with IFAP. Among these patients, 54 were treated by femoral artery ligation with concomitant thrombectomy. Open collateral circulations were assessed by intraoperative angiography, including detection of mean artery pressure (MAP) of back-flow from the profunda femoris artery and the superficial femoral artery after operation. Patients were followed up for 3-72 months (mean 35). The data were then subjected to statistical analysis. RESULTS Preoperative death occurred in one patient due to acute onset of drug addiction in the ward. Preoperatively, massive necrosis developed in the left limb of the only patient with bilateral IFAPs. All 54 patients underwent femoral artery ligation with concomitant thrombectomy, including nine cases of ligation of the external iliac artery and one case of above-knee limb amputation. All wounds were completely healed within 3 months. Six late deaths (11.1%), resulting solely from refractory drug addiction, were observed during the follow-up period, of which two occurred 2 years, one 4 years, and three 5 years postoperatively. No toe amputations were noted during the follow-up period. Fourteen patients (25.9%) developed intermittent claudication. One postoperative limb was lost. Of all 54 patients, 38 were subjected to collateral circulation assessment by intraoperative angiography. Collateral circulations were found well open in a baseline path with four stations down to the distal lower limbs of all assessed patients. Four preferred types of iliac-femoral collaterals were defined. Postoperatively, compared to the external iliac artery, the MAP levels of back-flow from the profunda femoris artery and the superficial femoral artery significantly dropped to 43.89+/-2.75 and 18.08+/-2.76 mm Hg, respectively. CONCLUSION As a result of femoral artery ligation without reconstruction, well open collateral circulations and acceptable distal arterial runoff blood are seen, which suggests that this procedure is a reliable alternative to the emergent treatment of IFAPs in drug addicts. However, arterial reconstruction may be used as a backup approach if necessary during observation.

The in vivo blood compatibility of bio-inspired small diameter vascular graft: effect of submicron longitudinally aligned topography.

BackgroundCardiovascular disease is the leading cause of deaths worldwide and the arterial reconstructive surgery remains the treatment of choice. Although large diameter vascular grafts have been widely used in clinical practices, there is an urgent need to develop a small diameter vascular graft with enhanced blood compatibility. Herein, we fabricated a small diameter vascular graft with submicron longitudinally aligned topography, which mimicked the tunica intima of the native arterial vessels and were tested in Sprague–Dawley (SD) rats.MethodsVascular grafts with aligned and smooth topography were prepared by electrospinning and were connected to the abdominal aorta of the SD rats to evaluate their blood compatibility. Graft patency and platelet adhesion were evaluated by color Doppler ultrasound and immunofluorescence respectively.ResultsWe observed a significant higher patency rate (p = 0.021) and less thrombus formation in vascular graft with aligned topography than vascular graft with smooth topography. However, no significant difference between the adhesion rates on both vascular grafts (smooth/aligned: 0.35‰/0.12‰, p > 0.05) was observed. Moreover, both vascular grafts had few adherent activated platelets on the luminal surface.ConclusionBionic vascular graft showed enhanced blood compatibility due to the effect of surface topography. Therefore, it has considerable potential for using in clinical application.

Scab-Inspired Cytophilic Membrane of Anisotropic Nanofibers for Rapid Wound Healing

This work investigates the influence of cytophilic and anisotropic nanomaterials on accelerated cell attachment and directional migration toward rapid wound healing. Inspired by the anisotropic protein nanofibers in scab, a polyurethane (PU) nanofibrous membrane with an aligned structure was fabricated. The membrane showed good affinity for wound-healing-related cells and could guide cell migration in the direction of PU nanofibers. Also, the morphology and distribution of F-actin and paxillin of attached cells were influenced by the underlying nanofibers. The randomly distributed PU nanofibers and planar PU membrane did not show a distinct impact on cell migration. This scab-inspired cytophilic membrane is promising in applications as functional interfacial biomaterials for rapid wound healing, bone repair, and construction of neural networks.

IP-10/CXCR3 Axis Promotes the Proliferation of Vascular Smooth Muscle Cells through ERK1/2/CREB Signaling Pathway

Excessive proliferation of vascular smooth muscle cells is one of the main pathological processes leading to atherosclerosis and intimal hyperplasia after vascular interventional therapy. Our previous study has shown that interferon-γ inducible protein-10 contributes to the proliferation of vascular smooth muscle cell. However, the underlying mechanisms remain unclear. Extracellular signal-regulated kinase 1/2, serine/threonine kinase Akt, and cAMP response element binding protein are signaling pathways, which are considered to play important roles in the processes of vascular smooth muscle cell proliferation. Moreover, chemokine receptor 3 and Toll-like receptor 4 are potential receptors of inducible protein-10 in this process. In the present study, IP-10 was found to directly induce vascular smooth muscle cell proliferation, and exposure to inducible protein-10 activated extracellular signal-regulated kinase 1/2, serine/threonine kinase, and cAMP response element binding protein signaling. Inhibitor of extracellular signal-regulated kinase 1/2, rather than inhibitor of serine/threonine kinase, inhibited the phosphorylation of cAMP response element binding protein and reduced inducible protein-10-stimulated vascular smooth muscle cell proliferation. Knockdown of cAMP response element binding protein by siRNA inhibited inducible protein-10-induced vascular smooth muscle cell proliferation. Moreover, anti-CXCR3 IgG, instead of anti-Toll-like receptor 4 IgG, reduced inducible protein-10-induced vascular smooth muscle cell proliferation and inducible protein-10-stimulated extracellular signal-regulated kinase 1/2 and cAMP response element binding protein activation. Together, these results indicate that inducible protein-10 promotes vascular smooth muscle cell proliferation via chemokine receptor 3 and activation of extracellular signal-regulated kinase 1/2 inducible protein-10-induced vascular smooth muscle cell proliferation. These data provide important targets for future studies to modulate atherosclerosis and restenosis after vascular interventional therapy.

Effects of Antiatherosclerosis in Carotid Artery by RNAi-Mediated Silencing of MCP-1 Expression

BACKGROUND Our objective was to identify the effects of MCP-1 siRNA in vivo transfection in an atherosclerosis model on local expression of MCP-1 and pathogenesis of atherosclerosis. METHODS Carotid atherosclerosis was induced in 28 New Zealand white rabbits. Rabbits were divided into three groups randomly: RNAi group, model group, and blank plasmid group. siRNA-expressing vector was transfected to blood vessels by liposomes. The carotid arteries were processed for morphological evaluation. Local expression of MCP-1 was detected by immunohistochemistry, RT-PCR, and Western blot. RESULTS On hematoxylin and eosin-stained sections, partial endothelial cells detached while intimae were less thickened in the RNAi group compared to the model and blank plasmid groups; the I:M ratio was significantly reduced to 1.46 in the RNAi group compared to the model and blank plasmid groups (5.55 and 5.27, respectively). The results of immunohistochemistry showed that MCP-1 expression was less colorized and less positive in the RNAi group. RT-PCR and Western blot showed reduced expression in the RNAi group than in the model and blank plasmid groups. There were highly positive correlations between semiquantitative RT-PCR and the I:M ratio (r = 0.968). CONCLUSION Expression of MCP-1 was successfully inhibited by transfecting MCP-1 siRNA expression plasmid to the carotid artery, and the progression of atherosclerosis was restricted by RNAi-mediated silencing of MCP-1 expression.

The value of endografts in the surgical management of arterial lesions secondary to Behçet disease

Background: This study summarizes our experience in the surgical management of arterial lesions secondary to Behçet disease (BD) and assesses the value of endografts. Methods: Data from BD patients with arterial lesions managed surgically in our center from January 1998 to December 2015 were studied retrospectively. Surgical procedures, graft selection, graft‐related complications, and retreatments were analyzed. Results: We recruited 33 patients (29 men and 4 women; male‐to‐female ratio, 7.25:1) with an average age of 36.7 years (range, 25‐51 years). The arterial lesions included 27 aneurysms in 24 patients and nine stenotic or occlusive lesions in nine patients. Immunosuppressive therapy was administered routinely preoperatively and postoperatively as recommended. Altogether, 15 great saphenous veins (GSVs), 8 synthetic grafts, and 13 endografts were used in 36 primary procedures. The mean follow‐up duration was 3.8 ± 2.9 years. Graft‐related pseudoaneurysm was seen in three GSVs (20%) and in three synthetic grafts (38%) at the anastomosis, but not in endograft implantations (log‐rank, P = .171). Graft occlusions were observed in 1 GSV (7%), 2 synthetic (25%), and 2 endografts (15%; log‐rank, P = .881). Graft infection occurred in one synthetic graft (13%) and in one endograft (8%) but not in the GSVs (log‐rank, P = .689). Graft‐related artery rupture occurred in only one endograft (8%). Two patients died, giving a mortality rate of 6.1%. Conclusions: In the surgical management of arterial lesions secondary to BD, endografts were superior to GSV and synthetic grafts in decreasing anastomotic pseudoaneurysm. However, improvements are needed to enhance the long‐term patency and reduce infections.