Poly(ethylene glycol) Hydrogels with the Sustained Release of Hepatocyte Growth Factor for Enhancing Vascular Regeneration.

The surface modification of biologically active factors on tissue-engineering vascular scaffold fails to fulfill the mechanical property and bioactive compounds' sustained release in vivo and results in the inhibition of tissue regeneration of small-diameter vascular grafts in vascular replacement therapies. In this study, biodegradable poly(ε-caprolactone) (PCL) was applied for scaffold preparation, and poly(ethylene glycol) (PG) hydrogel was used to load heparin and hepatocyte growth factor (HGF). In vitro analysis demonstrated that the PCL scaffold could inhibit the heparin release from the PG hydrogel, and the PG hydrogel could inhibit heparin release during the process of PCL degradation. Finally, it results in sustained release of HGF and heparin from the PCL-PG-HGF scaffold. The mechanical property of this hybrid scaffold improved after being coated with the PG hydrogel. In addition, the PCL-PG-HGF scaffold illustrated no inflammatory lesions, organ damage, or biological toxicity in all primary organs, with rapid organization of the endothelial cell layer, smooth muscle regeneration, and extracellular matrix formation. These results indicated that the PCL-PG-HGF scaffold is biocompatible and provides a microenvironment in which a tissue-engineered vascular graft with anticoagulant properties allows regeneration of vascular tissue (Scheme 1). Such findings confirm the feasibility of creating hydrogel scaffolds coated with bioactive factors to prepare novel vascular grafts.

Acute Paraplegia Result from Spinal Ischemia Nine Years After Hybrid Total Arch Repair with Frozen Elephant Trunk: A Case Report.

Spinal cord ischemia due to decreased cord perfusion is a devastating complication in patients with thoracoabdominal dissection following frozen elephant trunk (FET) repair surgery. However, rare occurrence of spinal cord ischemia leading to paraplegia after long-term follow-up of FET repair has been reported. Here, we describe a case of spinal cord ischemia resulting in paraplegia nine years after hybrid total arch repair with FET. Cerebrospinal fluid drainage and serial treatment were utilized to decrease intraspinal pressure and increase blood flow to the spinal cord. Three months after the onset of paraplegia and with treatment and rehabilitation, the patient recovered to walk.

Angiotensin-receptor blocker losartan alleviates atrial fibrillation in rats by downregulating frizzled 8 and inhibiting the activation of WNT-5A pathway.

Atrial fibrillation (AF) is a common arrhythmia. Angiotensin-receptor blocker (ARB) is related to AF treatment. This study explored the mechanism of ARB in AF. AF rat models were established by Ach-CaCl2 mixed solution injection. Rats were treated with ARB by gavage and injected with pcDNA3.1-based frizzled homolog 8 (FZD8) overexpression plasmids (oe-FZD8) through the tail vein. The 12-lead electrocardiogram was recorded by biological signal acquisition and processing system and AF duration was recorded, and atrial effective refractory period (AERP) was monitored by electrophysiology. Atrial fibrosis degree, FZD8 messenger RNA and protein levels, collagen I, collagen III, transforming growth factor ß1 (TGF-ß1), fibronectin, α smooth muscle actin (α-SMA), WBT-5B, and p-JNK1/2 levels, interleukin 1 ß (IL-1ß) and interleukin 6 (IL-6) levels were detected by Masson staining, reverse transcription quantitative polymerase chain reaction, western blot assay, immunohistochemistry, and enzyme-linked immunosorbent assay. ACh-CaCl2-induced AF rats showed a large area of fused necrosis, abnormal collagen fibre proliferation, high atrial fibrosis degree, and increased atrial fibrosis area in atrial interstitium, elevated collagen I, collagen III, TGF-ß1, fibronectin, α-SMA, IL-1ß, and IL-6 levels, whereas these trends were averted by ARB treatment. FZD8 was highly expressed in AF rat myocardium. ARB repressed FZD8 expression, prolonged AERP and reduced AF incidence. FZD8 overexpression annulled the effects of ARB on improving AF rat myocardial fibrosis. ARB inactivated the WNT-5A pathway by suppressing FZD8. ARB inactivated the WNT-5A pathway by silencing FZD8, therefore, alleviating AF rat atrial fibrosis.

Acute Paraplegia Result from Spinal Ischemia Nine Years After Hybrid Total Arch Repair with Frozen Elephant Trunk: A Case Report

ABSTRACT Spinal cord ischemia due to decreased cord perfusion is a devastating complication in patients with thoracoabdominal dissection following frozen elephant trunk (FET) repair surgery. However, rare occurrence of spinal cord ischemia leading to paraplegia after long-term follow-up of FET repair has been reported. Here, we describe a case of spinal cord ischemia resulting in paraplegia nine years after hybrid total arch repair with FET. Cerebrospinal fluid drainage and serial treatment were utilized to decrease intraspinal pressure and increase blood flow to the spinal cord. Three months after the onset of paraplegia and with treatment and rehabilitation, the patient recovered to walk.

Biological small-calibre tissue engineered blood vessels developed by electrospinning and in-body tissue architecture.

There are no suitable methods to develop the small-calibre tissue-engineered blood vessels (TEBVs) that can be widely used in the clinic. In this study, we developed a new method that combines electrospinning and in-body tissue architecture(iBTA) to develop small-calibre TEBVs. Electrospinning imparted mechanical properties to the TEBVs, and the iBTA imparted biological properties to the TEBVs. The hybrid fibres of PLCL (poly(L-lactic-co-ε-caprolactone) and PU (Polyurethane) were obtained by electrospinning, and the fibre scaffolds were then implanted subcutaneously in the abdominal area of the rabbit (as an in vivo bioreactor). The biotubes were harvested after four weeks. The mechanical properties of the biotubes were most similar to those of the native rabbit aorta. Biotubes and the PLCL/PU vascular scaffolds were implanted into the rabbit carotid artery. The biotube exhibited a better patency rate and certain remodelling ability in the rabbit model, which indicated the potential use of this hybridization method to develop small-calibre TEBVs. Sketch map of developing the biotube. The vascular scaffolds were prepared by electrospinning (A). Silicone tube was used as the core, and the vascular scaffold was used as the shell (B). The vascular scaffold and silicone tube were implanted subcutaneously in the abdominal area of the rabbit (C). The biotube was extruded from the silicone tube after 4 weeks ofembedding (D). The biotube was implanted for the rabbit carotid artery (E).

Risk factors for in-stent restenosis after vertebral artery stenting of V1 segment: A systematic review and meta-analysis.

OBJECTIVE: In-stent restenosis (ISR) remains a challenge in the treatment of vertebral artery V1 segment stenosis. The aim of this meta-analysis is to identify the risk factors of ISR. METHODS: Studies eligible for inclusion criteria were found in PubMed, Embase, and Cochrane Library databases. Data related to risk factors of ISR were extracted from the included studies, and pooled analysis was performed when data of the same factor were available in ≥2 studies. Dichotomous outcomes were analyzed with odds ratios (OR) and continuous outcomes were analyzed with a weighted mean difference (WMD). The Stata 14.0 program was used for the meta-analysis. RESULTS: A total of 11 studies involving 1356 patients were included in our analysis. Pooled analyses showed that younger age (p = 0.01; WMD= -1.958; 95% confidence interval [CI], -3.453 to -0.463) and V1 tortuosity (p = 0.004; OR = 4.145; 95% CI, 1.56-11.012) significantly associated with higher risk of ISR in V1 segment stenting. While bare-metal stents, stent diameter and length, diabetes mellitus, coronary artery disease, and smoking were not found to increase ISR rates. CONCLUSIONS: This meta-analysis showed that young age and V1 tortuosity increase the ISR rates after vertebral V1 segment stenting.

Gelatin coating promotes in situ endothelialization of electrospun polycaprolactone vascular grafts.

Rapid endothelialization is crucial for in situ tissue engineering vascular grafts to prevent graft failure in the long-term. Gelatin is a promising nature material that can promote endothelial cells (ECs) adhesion, proliferation, and migration. In this study, the internal surface of electrospun polycaprolactone (PCL) vascular grafts was coated with gelatin. Endothelialization and vascular wall remolding were investigated by imaging and histological studies in the rat abdominal aorta replacement model. The endothelialization of heparinized gelatin-coated PCL (GP-H) vascular grafts was more rapid and complete than heparinized PCL (P-H) grafts. Intimal hyperplasia was milder in the GP-H vascular grafts than the P-H vascular grafts in the long-term. Meanwhile, smooth muscle cells (SMCs) and extracellular matrix (ECM) regeneration were better in the GP-H vascular grafts. By comparison, an aneurysm was observed in the P-H group in 6 months. Calcification was observed in both groups. All vascular grafts were patient after implantation in both groups. Our results showed that gelatin coating on the internal surface of PCL grafts is a simple and effective way to promote endothelialization. A more rapid endothelialization and complete endothelium can inhibit intimal hyperplasia in the long-term.

Effectiveness of distal arterial bypass with porcine decellularized vascular graft for treating diabetic lower limb ischemia.

BACKGROUND: Application of tissue engineered vascular grafts for small-diameter artery reconstruction has been a much anticipated advance in vascular surgery. The aim of this study is to assess the effectiveness of small-diameter decellularized vascular grafts in below-knee bypass surgery for diabetic lower extremity ischemia. METHODS: Three patients with diabetic lower limb ischemia were admitted to the Department of Vascular Surgery, Xuanwu Hospital, Capital Medical University between May, 2010 and June, 2010. Decellularized porcine arteries with modified surface were implanted in the lower extremity for below-knee arterial revascularization. Imaging examination was performed for assessment of graft mechanical stability and patency at 1 month and 6 months after implantation. RESULTS: At 6 months after implantation, all three grafts were patent with no stenosis or aneurysm formation of the grafts were found on imaging assessment with primary patency rate of 100% (3/3) both at 1 month and 6 months after graft insertion. CONCLUSION: Decellularized vascular graft with surface modification for the small-diameter artery reconstruction had good clinical results after 6 months follow-up in three patients with diabetic lower limb ischemia.

Hydrogel Complex Electrospun Scaffolds and Their Multiple Functions in In Situ Vascular Tissue Engineering.

Hydrogel complex scaffolds (hydrogel scaffolds) are prepared by coating precursor solutions onto heparin-modified poly(ε-caprolactone) (PCLH) scaffolds followed by subsequent in situ gelation. Here, we show that hydrogel complexation can significantly strengthen the scaffold and slow its degradation. The hydrogel scaffold was implanted into the abdominal aorta of a rat model, and the aneurysm incidence rate of the hydrogel scaffolds sharply decreased compared with that of the hydrogel-free scaffolds. Histological and immunohistological analyses showed that the implanted grafts had good vascular regeneration. The absence of calcification and occurrence of contractile smooth muscle cells (SMCs) at the first month was found in the hydrogel-free PCLH scaffold due to the presence of surface-modified heparin, whereas the hydrogel scaffold exhibited mild calcification and later occurrence of contractile SMCs as the complexed hydrogel covered the fibers and blocked the interaction between heparin and cells. Heparin was further physically encapsulated into the hydrogel before gelation, and its sustainable release was demonstrated by an in vitro release test. A pilot implantation in a rabbit carotid model showed that the encapsulated heparin modulated the scaffold characteristics including anticoagulation, anticalcification, and the early occurrence of contractile SMCs in vivo. Consequently, hydrogel complexation can significantly improve the in vivo regeneration property of the scaffold due to its multiple beneficial characteristics.

In situ hydrogel dressing loaded with heparin and basic fibroblast growth factor for accelerating wound healing in rat.

In order to accelerate the healing of chronic wound, a hydrogel dressing encapsulating with heparin and basic fibroblast growth factor is prepared by the Michael addition of 4-arm acrylated polyethylene glycol and dithiothreitol. As-prepared hydrogel dressing can combine the advantages of wet healing theory and exogenous growth factor supplement. Furthermore, the encapsulated heparin can play a role in diminishing inflammation and accelerating wound healing in addition to its well-known function of stabilizing basic fibroblast growth factor. In vitro release test shows the hydrogel network is able to sustainably release basic fibroblast growth factor within 10 days by the regulation of heparin, while released growth factor can significantly promote fibroblast's proliferation in vitro. Moreover, the wound healing in rat shows that as-prepared hydrogel dressing could accelerate wound healing in vivo much more effectively compared with blank hydrogel dressing and negative control. Hematoxylin-eosin and Masson's Trichrome staining exhibit the formation of complete and uniform epidermis. Immunohistochemical staining exhibits heparin can help hydrogel dressing to possess low inflammation in early stage, which is beneficial for accelerating wound healing as well as preventing the production of scar tissue. The enzyme-linked immunosorbent assay results demonstrate the exogenous bFGF in hydrogel can significantly upgrade the expressing of vascular endothelial growth factor and transforming growth factor-ß in wound site, which indicate better angiogenesis, and better on-site cell proliferation in wound site, respectively. Those results are further demonstrated by immunohistochemical and immunofluorescence staining. Consequently, as-prepared hydrogel dressing shows promising potential to perform better therapy efficacy in clinic for accelerating wound healing.

Biocompatibility evaluation of heparin-conjugated poly(ε-caprolactone) scaffolds in a rat subcutaneous implantation model.

Vascular grafts prepared from synthetic polymers have serious shortcomings that can be resolved by surface modification, such as by immobilizing heparin. In this study, the mechanical properties, biocompatibility, anticoagulation property, and water contact angle of two heparin-conjugated poly(ε-caprolactone) scaffolds (PCL-hexamethylendiamine-heparin, PCL-HMD-H. PCL-lysine-heparin, PCL-LYS-H) were compared to identify a preferred heparin conjugation method. An evaluation of the subcutaneous tissue biocompatibility of the scaffolds demonstrated that PCL-HMD-H had better endothelial cell proliferation than the PCL-LYS-H and was therefore a promising scaffold candidate for use in vascular tissue-engineering.

Decellularization, cross-linking and heparin immobilization of porcine carotid arteries for tissue engineering vascular grafts.

Tissue engineering vascular grafts (TEVGs) have the potential to replace small-diameter grafts in bypass surgery which is good news for patients with cardiovascular disease. Decellularized arteries can be ideal TEVGs because their natural three-dimensional structures support the migration of host cells and vascular remodeling. There are many methods for decellularization without a standard protocol. In this study, a combination of Triton X-100 and sodium dodecyl sulfate (SDS) were used to prepare decellularized arteries. However, decellularization may damage the biochemical and mechanical properties to some degree. We used the cross-linking agents N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to improve mechanical properties and immobilize heparin to inhibit thrombogenesis. Histological analysis, scanning electron microscopy, biomechanical properties test, determination of immobilized heparin, active partial thrombin time assay, and subcutaneous embedding experiment were used to evaluate the efficiency of decellularization and the efficacy of heparinized cross-linked vascular scaffold. Results showed 1% Triton X-100 combined with 0.3% SDS can decellularize successfully. EDC and NHS cross-linking can improve the mechanical properties, reduce the inflammatory reaction and slow the degradation time. Heparin immobilized on the scaffolds can inhibit thrombogenesis effectively. This study indicated the heparinized cross-linked vascular scaffolds may be ideal scaffolds for TEVGs.

Preparation of Small-Diameter Tissue-Engineered Vascular Grafts Electrospun from Heparin End-Capped PCL and Evaluation in a Rabbit Carotid Artery Replacement Model.

Aiming to construct small diameter (ID <6 mm) off-the-shelf tissue-engineered vascular grafts, the end-group heparinizd poly(ε-caprolactone) (PCL) is synthesized by a three-step process and then electrospun into an inner layer of double-layer vascular scaffolds (DLVSs) showing a hierarchical double distribution of nano- and microfibers. Afterward, PCL without the end-group heparinization is electrospun into an outer layer. A steady release of grafted heparin and the existence of a glycocalyx structure give the grafts anticoagulation activity and the conjugation of heparin also improves hydrophilicity and accelerates degradation of the scaffolds. The DLVSs are evaluated in six rabbits via a carotid artery interpositional model for a period of three months. All the grafts are patent until explantation, and meanwhile smooth endothelialization and fine revascularization are observed in the grafts. The composition of the outer layer of scaffolds exhibits a significant effect on the aneurysm dilation after implantation. Only one aneurysm dilation is detected at two months and no calcification is formed in the follow-up term. How to prevent aneurysms remains a challenging topic.

Dysphagia and aspiration pneumonia in elderly hospitalization stroke patients: Risk factors, cerebral infarction area comparison.

OBJECTIVE: Stroke is the most common neurological disease that is associated with deglutition disorders. The aim of this study was to analyze dysphagia and aspiration pneumonia risk factors in post-stroke elderly inpatients. METHOD: We consecutively enrolled 212 stroke patients over sixty years of age from July 2014 to June 2015. Seventeen patients were eliminated. Stroke patients' demographics, clinical symptoms and biochemistry data were collected. Modified water swallowing test was used for the assessment of deglutition difficulty. These inpatients were classified into two groups: territorial anterior circulation infarction (n= 114) and territorial posterior circulation infarction (n= 82). Finally, dysphagia and aspiration pneumonia risk factor were analyzed between these two groups. RESULT: Number of previous cerebral infarction, National Institutes of Health Stroke Scale (NIHSS) score, masticatory muscle paralysis, abolition of gag reflex were correlated with the deglutition difficulty in these patients. In addition, NIHSS score (p= 0.017) and dysphagia (p= 0.02) were correlated with aspiration pneumonia. CONCLUSION: In stroke inpatients over sixty years of age, it is necessary to distinguish the patients with multiple previous cerebral infarctions, high NIHSS score, masticatory muscle paralysis, and abolition of gag reflex for early detection and rehabilitation of dysphagia.

Vascular Remodeling Process of Heparin-Conjugated Poly(ε-Caprolactone) Scaffold in a Rat Abdominal Aorta Replacement Model.

In the field of vascular graft research, poly-ε-caprolactone (PCL) is used owing to its good mechanical strength and biocompatibility. In this study, PCL scaffold was prepared by electrospinning and surface modification with heparin via hexamethylenediamine. Then the scaffolds were implanted into the infrarenal abdominal aorta of Wistar rats and contrast-enhanced micro-ultrasound was used to monitor the patency of grafts after implantation. These grafts were extracted from the rats at 1, 3, and 6 months for histological analysis, immunofluorescence staining, and scanning electron microscopy observation. Although some grafts experienced aneurysmal change, results showed that all implanted grafts were patent during the course of 6 months and these grafts demonstrated well-organized neotissue with endothelium formation, smooth muscle regeneration, and extracellular matrix formation. Such findings confirm feasibility to create heparin-conjugated scaffolds of next-generation vascular grafts.

Preparation and evaluation of decellularized porcine carotid arteries cross-linked by genipin: the preliminary results.

Decellularized arteries have been considered as promising scaffolds for small-diameter vascular substitutes. However, weakened mechanical properties, immunological rejection and rapid degradation after transplantation still exist after decellularization. Previous studies indicated that genipin cross-linking can solve these problems. Therefore, genipin was selected as the cross-linking agent for the pre-treatment of decellularized arteries in our study. Histological analysis, scanning electron microscopy, mechanical properties analysis and subcutaneous embedding experiment were adopted to investigate the efficiency of decellularization and the effect of genipin cross-linking on improving mechanical, structural and biological properties of decellularized arteries. Decellularization protocols based on three trypsin concentrations were used to prepare decellularized arteries, after decellularization, arteries were cross-linked with genipin. Results showed that 0.5% trypsin was the most efficient concentration to remove cellular components and preserve ECM. However, mechanical properties of 0.5% trypsin decellularized arteries weakened significantly, while genipin cross-linking improved mechanical properties of decellularized arteries to the same level as fresh arteries. After 4 weeks subcutaneous embedding, cross-linked arteries caused the mildest inflammatory response. In conclusion, genipin could be employed as an ideal cross-linking agent to strengthen mechanical properties, enhance the resistance to degradation and reduce the antigenicity of decellularized arteries for small-diameter blood vessel tissue engineering applications.