Feng Ran

Development and validation of small-diameter vascular tissue from a decellularized scaffold coated with heparin and vascular endothelial growth factor.

To overcome shortcomings of current small-diameter vascular prostheses, we developed a novel allogenic vascular graft from a decellularized scaffold modified through heparin immobilization and vascular endothelial growth factor (VEGF) coating. The VEGF coating and release profiles were assayed by enzyme-linked immunosorbent assay, the biological activity of modified surface was validated by human umbilical vein endothelial cells seeding and proliferation for 10 days in vitro. In vivo, we implanted either a modified or a nonmodified scaffold as bilateral carotid allogenic graft in canines (n = 15). The morphological examination of decellularized scaffolds showed complete removal of cellular components while the extracellular matrix structure remained intact. After modification, the scaffolds possessed local sustained release of VEGF up to 20 days, on which the cells cultured showed significantly higher proliferation rate throughout the time after incubation compared with the cells cultured on nonmodified scaffolds (P < 0.0001). After 6 months of implantation, the luminal surfaces of modified scaffolds exhibited complete endothelium regeneration, however, only a few disorderly cells and thrombosis overlay the luminal surfaces of nonmodified scaffolds. Specifically, the modified scaffolds exhibited significantly smaller hyperplastic neointima area compared with the nonmodified, not only at midportion (0.56 +/- 0.07 vs. 2.04 +/- 0.12 mm(2), P < 0.0001), but also at anastomotic sites (1.76 +/- 0.12 vs. 3.67 +/- 0.20 mm(2), P < 0.0001). Moreover, modified scaffolds had a significantly higher patency rate than the nonmodified after 6 months of implantation (14/15 vs. 7/15, P = 0.005). Overall, this modified decellularized scaffold provides a promising direction for fabrication of small-diameter vascular grafts.

Tissue engineering of small‐diameter vascular grafts by endothelial progenitor cells seeding heparin‐coated decellularized scaffolds

Successful construction of a small-diameter bioartificial vascular graft remains a great challenge. This study reports on novel tissue engineering vascular grafts (TEVGs) constructed by endothelial progenitor cells and heparin-coated decellularized vessels (DV). The DVs were fabricated from canine carotid arteries with observable depletion of cellular components. After heparin coating, the scaffolds possessed excellent antithrombogeneity. Canine endothelial progenitor cells harvested from peripheral blood were expanded and seeded onto heparin-coated DVs and cocultured in a custom-made bioreactor to construct TEVGs. Thereafter, the TEVGs were implanted into the carotid arteries of cell-donor dogs. After 3 months of implantation, the luminal surfaces of TEVGs exhibited complete endothelium regeneration, however, only a few disorderly cells and thrombosis overlaid the luminal surfaces of control DVs grafts, and immunofluorescent staining showed that the seeded cells existed in the luminal sides and the medial parts of the explanted TEVGs and partially contributed to the endothelium formation. Specifically, TEVGs exhibited significantly smaller hyperplastic neointima area compared with the DVs, not only at midportion (0.64 ± 0.08 vs. 2.13 ± 0.12 mm(2) , p < 0.001), but also at anastomotic sites (proximal sites, 1.03 ± 0.09 vs. 3.02 ± 0.16 mm(2), p < 0.001; distal sites, 1.84 ± 0.15 vs. 3.35 ± 0.21 mm(2), p < 0.001). Moreover, TEVGs had a significantly higher patency rate than the DVs after 3 months of implantation (19/20 vs. 12/20, p < 0.01). Overall, this study provided a new strategy to develop small-diameter TEVGs with excellent biocompatibility and high patency rate.

Beneficial effects of granulocyte-colony stimulating factor on small-diameter heparin immobilized decellularized vascular graft.

Autologous recellularization of decellularized scaffolds is a promising challenge in the field of tissue-engineered vascular graft and could be boosted by endothelial progenitor cells (EPCs). The purpose of this study was to examine the effects of granulocyte-colony stimulating factor (G-CSF) treatment on this process. Heparin immobilized decellularized grafts were fabricated and implanted into 48 rats, of which 25 rats received G-CSF (50 ug/kg/day) for 14 days after operation (G-CSF group) and other 23 received saline serving as control. Five animals of each group were euthanized at 2 weeks for analysis of early graft endothelialization; whereas the rest were investigated by Doppler ultrasound to monitor the graft patency rate up to 6 months. After 14 days of G-CSF administration, the number of CD(34) (+)/CD(133) (+) progenitor cells was increased by 16.2 folds, and endothelial cell-specific immunostaining revealed an enhancement of early endothelialization in G-CSF group. After 6 months of implantation, the G-CSF treated grafts exhibited a significantly smaller hyperplastic neointima area compared with the controls, not only at midportion (0.38 ± 0.02 vs. 0.47 ± 0.07 mm(2), p < 0.0001), but also at distal anastomosis (0.42 ± 0.04 vs. 0.70 ± 0.13 mm(2), p < 0.0001). Moreover, G-CSF treated grafts had a higher patency rate compared with the control animals (19/20 vs. 12/18, p = 0.005). In conclusion, G-CSF-induced mobilization of circulating EPCs regenerated endothelium and inhibited neointimal hyperplasia of small-diameter heparinized decellularized vascular graft. This cytokine therapy may be a feasible strategy for the improvement of patency rate of the novel allogeneic graft.

Tanshinone IIA attenuates elastase-induced AAA in rats via inhibition of MyD88-dependent TLR-4 signaling

BACKGROUND The purpose of this study was to determine whether myeloid differentiation factor88-dependent Toll-Like Receptor-4 (TLR-4) signaling contributed to the inhibition of abdominal aortic aneurysm (AAA) by Tanshinone IIA (Tan IIA). MATERIALS AND METHODS Male Sprague-Dawley rats (n = 12 / group) were randomly distributed into three groups: Tan IIA, control, and sham. The rats from Tan IIA and control groups under-went intra-aortic elastase perfusion to induce AAAs, and those in the sham group were perfused with saline. Only the Tan IIA group received Tan IIA (2 mg / rat / d). Aortic tissue samples were harvested at 24 d after perfusion and evaluated using reverse transcriptase-polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence. RESULTS The over-expression of Toll-Like Receptor-4 (TLR-4), Myeloid Differentiation factor 88 (MyD88), Phosphorylated Nuclear Factor κB (pNF-κB) and Phosphorylated IκBα (pIκBα) induced by elastase perfusion were significantly decreased by Tan IIA treatment. CONCLUSIONS Tan IIA attenuates elastase-induced AAA in rats possibly via the inhibition of MyD88-dependent TLR-4 signaling, which may be one potential explanation of why Tan IIA inhibits AAA development through multiple effects.

Evaluation of in vitro and in vivo biocompatibility of a myo-inositol hexakisphosphate gelated polyaniline hydrogel in a rat model

Recent advances in understanding the interaction between electricity and cells/biomolecules have generated great interest in developing biocompatible electrically conductive materials. In this study, we investigated the biocompatibility of a myo-inositol hexakisphosphate gelated polyaniline hydrogel using in vitro and in vivo experiments in a rat model. The polyaniline hydrogel was used to coat a polycaprolactone scaffold and was cultured with rat endothelial progenitor cells differentiated from rat adipose-derived stem cells. Compared with the control sample on a pristine polycaprolactone scaffold, the treated polyaniline hydrogel had the same non-poisonous/cytotoxicity grade, enhanced cell adhesion, and a higher cell proliferation/growth rate. In implant studies, the polyaniline hydrogel sample induced milder inflammatory responses than did the control at the same time points. Combining the advantages of a biocompatible hydrogel and an organic conductor, the inositol phosphate-gelated polyaniline hydrogel could be used in bioelectronics applications such as biosensors, neural probes, cell stimulators, medical electrodes, tissue engineering, and electro-controlled drug delivery.

A Novel Mutation of SMAD3 Identified in a Chinese Family with Aneurysms-Osteoarthritis Syndrome

Aneurysms-osteoarthritis syndrome (AOS) is a recently delineated autosomal dominant disorder characterized by aneurysms, dissections, and tortuosity throughout the arterial tree in association with early onset osteoarthritis, mild craniofacial features, and skeletal and cutaneous anomalies. Previous studies have demonstrated that mutations in SMAD3, a key regulator of TGF-β signal transduction, contribute to AOS. Here, we investigated a family of three generations affected by AOS. A novel SMAD3 mutation, c.266G>A (p.C89Y), was identified and cosegregated with the affected individuals in this family. Our finding expands the mutation spectrum of SMAD3 gene and further strengthens the connection between the presence of aneurysms-osteoarthritis phenotype and SMAD3 mutations, which facilitates the understanding of the genotype-phenotype correlation of AOS.

Computed Tomography-Based Study Exploring the Feasibility of Endovascular Treatment of Type A Aortic Dissection in the Chinese Population

Purpose To characterize type A aortic dissection (TAAD) in the Chinese population using high-resolution computed tomography (CT) and explore potential candidacy for endovascular repair of TAAD. Methods The imaging studies and medical records of all 302 patients presenting with TAAD at two Chinese hospitals from 2010 to 2013 were reviewed. Of these, 221 patients were excluded because of missing/inadequate preoperative CT scans. The remaining 91 patients (64 men; mean age 51.1±7.5 years) had CT data adequate to assess anatomical suitability for endovascular treatment. Entry tears were identified using multiplanar reconstructions, while morphological measurements were based on a centerline of flow (CLF) technique. Suitability for endovascular treatment was based on a proximal landing zone ≥20 mm long, a true lumen aortic diameter ≤38 mm, and a total aortic diameter ≤46 mm; no coronary bypass grafts originating from the ascending aorta; no malfunctioning aortic valve; and good cerebral and cardiac perfusion. Results In the 91 patients, the precise location of the primary proximal entry tear could be identified in only 34 (37.4%) patients; in these patients, the identifiable intimal tears were located 36.4±41.0 mm distal to the closest coronary artery. The CLF was successfully generated in the CT scans of all patients; the mean lumen and total aortic lumen diameters at the entry tear level were 37.6±6.3 and 44.3±13.3 mm, respectively. Based on the CT measurements, stent-graft repair would have been anatomically feasible in 35 (38.5%) patients. No proximal landing zone (n=23), large aortic diameter (n=15), abnormal aortic valve (n=10), previous coronary bypass graft surgery (n=5), and poor cerebral and cardiac perfusion (n=3) were obstacles that affected the suitability for this treatment. Conclusion Based on high-resolution CT scans, our pilot study suggested that 38% of Chinese patients with TAAD could potentially be treated by stent-grafting based on the anatomical characteristics of the proximal dissection.

Preventive effects of basic fibroblast growth factor on vascular restenosis after balloon angioplasty

The aim of the present study was to investigate whether chronic administration of basic fibroblast growth factor (bFGF) following angioplasty in a dog model of atherosclerotic iliac stenosis may restore endothelium function and prevent restenosis (RS). In total, 40 dogs with atherosclerotic stenosis of the right iliac arteries were used in the study. A total of 20 dogs underwent histological examination of the lumen areas prior to (n=10) and immediately following angioplasty (n=10). Intravenous bFGF was administered to 10 dogs (bFGF group) and an additional 10 dogs received vehicle injection (control group). Animals in the two groups were sacrificed 42 days following surgery for in vitro analysis of vascular reactivity and morphometric assessment of the histological cross-sectional areas. The bFGF group exhibited significantly greater maximal endothelium-dependent acetylcholine-induced relaxation (Emax, 43±9%) when compared with the control group (Emax, 8±6%; P<0.05). In addition, the maximal endothelium-independent response of the bFGF group to sodium nitroprusside (Emax, 90±2%) was greater than that of the control group (Emax, 60±2%; P<0.05). Six weeks following angioplasty, the lumen area in the bFGF group (2.01±0.78 mm2) was greater compared with the control group (1.0±0.10%). The lumen area decreased by 58% between immediately after angioplasty and the control group six weeks following angioplasty. Therefore, the results of the present study indicated that administration of bFGF may not only restore endothelium-dependent and -independent relaxation, but also prevent RS in dogs that have undergone angioplasty.

Identification of a missense mutation of COL3A1 in a Chinese family with atypical Ehlers-Danlos syndrome using targeted next-generation sequencing

Aortopathy represents an important cause of mortality in industrialized countries, with a number of genes identified as predispose factors. It can be difficult to identify the genetic lesions underlying this disorder, particularly when the phenotype is atypical. The present study performed targeted next-generation sequencing of 428 genes associated with cardiovascular diseases in a family with aortopathy, the proband of which presented with abdominal aortic aneurysm rupture only, with tissue fragility noted in surgery. After targeted capture, sequencing and bioinformatics analysis, a missense mutation, p.A1259T, was identified in the collagen type III α1 (COL3A1) gene and co-segregated with the disease in the family. Crystal structure modeling revealed abnormal hydrogen bonds generated by the mutation, which likely affected the spatial structure of the procollagen C-propeptide. Mutations in the procollagen C-propeptide are rare and genotype-phenotype correlation may explain the atypical manifestations of affected individuals. The results of the present study suggested that targeted gene capture combined with next-generation sequencing can serve as a useful technique in the genetic diagnosis of aortopathy, particularly in the content of an atypical phenotype.

Treatment of serious complications following endovascular aortic repair for type B thoracic aortic dissection

Objective This study aimed to describe treatment of serious complications after primary thoracic endovascular aortic repair (TEVAR) in type B aortic dissection. Methods From June 2008 to March 2016, serious complications occurred in 58 patients without Marfan syndrome who received TEVAR for type B aortic dissection. Results Complications included endoleak, distal true lumen collapse, retrograde dissection, stroke, stent–graft (SG) migration and mistaken deployment, lower limb ischaemia, and SG fracture. Treatment included endovascular repair, surgical procedures, or conservative medication. Forty-six patients recovered from complications. Twelve patients were not cured. The median follow-up time was 29.5 months (2–61 months). The overall 30-day mortality rate was 1.7% (1/58) and the total mortality rate following secondary complications was 8.6% (5/58). The causes of death were stroke and aortic rupture. Conclusion Some treatments need to be performed after TEVAR because of severe complications. A reduction in these complications can be achieved by optimal evaluation of patients, selection of SGs, and specialized endovascular manipulation.