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.

Cobalt loaded electrospun poly(ε-caprolactone) grafts promote antibacterial activity and vascular regeneration in a diabetic rat model.

Diabetes has been associated with postoperative complications, such as increased risk of tissue infection and impaired tissue repair caused by destabilization of hypoxia-inducible factor-1α (HIF-1α). Consequently, it is imperative to fabricate anti-bacterial and pro-regenerative small-diameter vascular grafts for treating cardiovascular disease in diabetic patients. Herein, we developed electrospun cobalt ion (Co2+)-loaded poly (ε-caprolactone) (PCL) microfiber vascular grafts (PCL-Co grafts). The released Co2+ significantly increased the stabilization of HIF-1α in high-glucose (HG)-treated HUVECs (HG-HUVECs) and macrophages (HG-macrophages). This resulted in enhanced cell migration, nitric oxide production, and secretion of bioactive factors by HG-HUVECs, and polarization of HG-macrophages toward M2 phenotypes in vitro. The Co2+ also conferred anti-bacterial properties to the grafts, while not perturbing the inherent anti-bacterial activities of HG-macrophages. Following abdominal artery implantation into type 2 diabetes mellitus (T2DM) rats, PCL-Co grafts were evaluated for performance in infection (grafts pre-contaminated with Staphylococcus aureus) and prophylaxes models (grafts alone). PCL-Co grafts prevented the incidence of subsequent infection in prophylaxes model and effectively inhibited the bacterial growth in the infection model. PCL-Co grafts also significantly enhanced cellularization, vascularization, endothelialization, contractile SMC regeneration and macrophages polarization in both models. Collectively, PCL-Co grafts exhibited the potential to combat infection and improve tissue regeneration under diabetes conditions.

Optimal therapeutic conditions for the neural stem cell-based management of ischemic stroke: a systematic review and network meta-analysis based on animal studies.

BACKGROUND: In order to promote the clinical translation of preclinical findings, it is imperative to identify the most optimal therapeutic conditions and adopt them for further animal and human studies. This study aimed to fully explore the optimal conditions for neural stem cell (NSC)-based ischemic stroke treatment based on animal studies. METHODS: The PubMed, Ovid-Embase, and Web of Science databases were searched in December 2021. The screening of search results, extraction of relevant data, and evaluation of study quality were performed independently by two reviewers. RESULTS: In total, 52 studies were included for data analysis. Traditional meta-analysis showed that NSCs significantly reduced the modified neurological severity score (mNSS) and volume of cerebral infarct in animal models of ischemic stroke. Network meta-analysis showed that allogeneic embryonic tissue was the best source of NSCs. Further, intracerebral transplantation was the most optimal route of NSC transplantation, and the acute phase was the most suitable stage for intervention. The optimal number of NSCs for transplantation was 1-5×105 in mouse models and 1×106 or 1.8×106 in rat models. CONCLUSIONS: We systematically explored the therapeutic strategy of NSCs in ischemic stroke, but additional research is required to develop optimal therapeutic strategies based on NSCs. Moreover, it is necessary to further improve and standardize the design, implementation, measuring standards, and reporting of animal-based studies to promote the development of better animal experiments and clinical research.

Effect of a Drug-Eluting Stent vs. Bare Metal Stent for the Treatment of Symptomatic Intracranial and Vertebral Artery Stenosis.

Background: For patients with symptomatic intracranial and vertebral artery stenosis who receive endovascular treatment, in-stent restenosis (ISR) is associated with the recurrence of ischemic stroke. This study evaluated a drug-eluting stent (DES) vs. bare metal stent (BMS) for the treatment of symptomatic intracranial and vertebral artery stenosis. Methods: The trial was a multicenter, 1:1 randomized, prospective feasibility clinical trial with 10 participating centers in China from March 2014 to October 2015. Eligible patients had symptomatic intracranial and vertebral artery stenosis (70%-99%) and had medical drug treatment failure. The primary endpoint was the rate of in-stent restenosis at 180 days of randomization. The secondary endpoint was a composite of the following two outcomes: (1) ischemic stroke or transient cerebral ischemia (TIA) in the same territory as the presenting event (distal to the target lesion) between 30 days and 1 year after randomization and (2) successful stent implantation. The safety outcome was the presence of stroke in any territory and death within 30 days of randomization or adverse events. Group t-tests or Wilcoxon rank-sum tests were used for the intergroup comparison of quantitative data according to the data distribution. The chi-square test or exact probability method was used for the classification data. The Wilcoxon rank-sum test or CMH test was used for the categorical data. Results: We enrolled 188 patients at 10 medical centers in China (92 assigned to the DES group and 96 to the BMS group). The mean age of the 188 study participants was 61.6 years (range, 38-75 years); 152 participants (80.9%) were male. There were 28 patients (43.8%) with an ISR at 180 days in the BMS group and 10 patients (14.5%) in the DES group [risk difference, 29.3% (95% CI, 14.5%-44.0%); P = 0.001]. The percent of patients with ischemic stroke or TIA in the same territory between 30 days and 1 year was 5.2% (5/96) in the BMS group and 2.2% (2/92) in the DES group [risk difference, 3.0%; (95% CI, -2.3% to 8.2%); P = 0.354]. The percent of patients with successful stent implantation was 99.0% (95/96) in the BMS group and 97.8% (90/92) in the DES group [risk difference, 1.1%; (95% CI, -1.7% to 3.9%); P = 0.584]. In total, five patients (5.2%) in the BMS group and three patients (3.3%) in the DES group [risk difference, 1.9%; (95% CI, -2.3% to 6.1%); P = 0.721] had stroke in any territory and death within the 30-day follow-up. Total adverse events occurred 167 times in 72 patients (75.0%) in the BMS group compared with 114 times in 59 patients (64.1%) in the DES group [risk difference, 10.9%; (95% CI, -0.1% to 21.7%); P = 0.115]. Conclusions: Among patients with symptomatic intracranial arterial stenosis and vertebral artery stenosis, the use of a drug-eluting stent compared with a bare metal stent resulted in a decreased risk of ISR, similar successful stent implantation, and similar adverse events. These findings support the use of a drug-eluting stent for patients with symptomatic intracranial arterial stenosis and vertebral artery stenosis. Clinical Trial Registration: http://www.chictr.org.cn/showproj.aspx?proj=148272, identifier: ChiCTR2200055925.

The loading of C-type natriuretic peptides improved hemocompatibility and vascular regeneration of electrospun poly(ε-caprolactone) grafts.

As a result of thrombosis or intimal hyperplasia, synthetic artificial vascular grafts had a low success rate when they were used to replace small-diameter arteries (inner diameter < 6 mm). C-type natriuretic peptides (CNP) have anti-thrombotic effects, and can promote endothelial cell (EC) proliferation and inhibit vascular smooth muscle cell (SMC) over-growth. In this study, poly(ε-caprolactone) (PCL) vascular grafts loaded with CNP (PCL-CNP) were constructed by electrospinning. The PCL-CNP grafts were able to continuously release CNP at least 25 days in vitro. The results of scanning electron microscopy (SEM) and mechanical testing showed that the loading of CNP did not change the microstructure and mechanical properties of the PCL grafts. In vitro blood compatibility analysis displayed that PCL-CNP grafts could inhibit thrombin activity and reduce platelet adhesion and activation. In vitro cell experiments demonstrated that PCL-CNP grafts activated ERK1/2 and Akt signaling in human umbilical vein endothelial cells (HUVECs), as well as increased cyclin D1 expression, enhanced proliferation and migration, and increased vascular endothelial growth factor (VEGF) secretion and nitric oxide (NO) production. The rabbit arteriovenous (AV)-shunt ex vitro indicated that CNP loading significantly improved the antithrombogenicity of PCL grafts. The assessment of vascular grafts in rat abdominal aorta implantation model displayed that PCL-CNP grafts promoted the regeneration of ECs and contractile SMCs, modulated macrophage polarization toward M2 phenotype, and enhanced extracellular matrix remodeling. These findings confirmed for the first time that loading CNP is an effective approach to improve the hemocompatibility and vascular regeneration of synthetic vascular grafts. STATEMENT OF SIGNIFICANCE: Small-diameter (< 6 mm) vascular grafts (SDVGs) have not been made clinically available due to their prevalence of thrombosis, limited endothelial regeneration and intimal hyperplasia. The incorporation of bioactive molecules into SDVGs serves as an effective solution to improve hemocompatibility and endothelialization. In this study, for the first time, we loaded C-type natriuretic peptides (CNP) into PCL grafts by electrospunning and confirmed the effectiveness of loading CNP on improving the hemocompatibility and vascular regeneration of artificial vascular grafts. Regenerative advantages included enhancement of endothelialization, modulation of macrophage polarization toward M2 phenotypes, and improved contractile smooth muscle cell regeneration. Our investigation brings attention to CNP as a valuable bioactive molecule for modifying cardiovascular biomaterial.

Highly Bright AIE Nanoparticles by Regulating the Substituent of Rhodanine for Precise Early Detection of Atherosclerosis and Drug Screening.

Fluorescent probes capable of precise detection of atherosclerosis (AS) at an early stage and fast assessment of anti-AS drugs in animal level are particularly valuable. Herein, a highly bright aggregation-induced emission (AIE) nanoprobe is introduced by regulating the substituent of rhodanine for early detection of atherosclerotic plaque and screening of anti-AS drugs in a precise, sensitive, and rapid manner. With dicyanomethylene-substituted rhodanine as the electron-withdrawing unit, the AIE luminogen named TPE-T-RCN shows the highest molar extinction coefficient, the largest photoluminescence quantum yield, and the most redshifted absorption/emission spectra simultaneously as compared to the control compounds. The nanoprobes are obtained with an amphiphilic copolymer as the matrix encapsulating TPE-T-RCN molecules, which are further surface functionalized with anti-CD47 antibody for specifically binding to CD47 overexpressed in AS plaques. Such nanoprobes allow efficient recognition of AS plaques at different stages in apolipoprotein E-deficient (apoE-/- ) mice, especially for the recognition of early-stage AS plaques prior to micro-computed tomography (CT) and magnetic resonance imaging (MRI). These features impel to apply the nanoprobes in monitoring the therapeutic effects of anti-AS drugs, providing a powerful tool for anti-AS drug screening. Their potential use in targeted imaging of human carotid plaque is further demonstrated.

The effect of hypoxia-mimicking responses on improving the regeneration of artificial vascular grafts.

Cellular transition to hypoxia following tissue injury, has been shown to improve angiogenesis and regeneration in multiple tissues. To take advantage of this, many hypoxia-mimicking scaffolds have been prepared, yet the oxygen access state of implanted artificial small-diameter vascular grafts (SDVGs) has not been investigated. Therefore, the oxygen access state of electrospun PCL grafts implanted into rat abdominal arteries was assessed. The regions proximal to the lumen and abluminal surfaces of the graft walls were normoxic and only the interior of the graft walls was hypoxic. In light of this differential oxygen access state of the implanted grafts and the critical role of vascular regeneration on SDVG implantation success, we investigated whether modification of SDVGs with HIF-1α stabilizer dimethyloxalylglycine (DMOG) could achieve hypoxia-mimicking responses resulting in improving vascular regeneration throughout the entirety of the graft wall. Therefore, DMOG-loaded PCL grafts were fabricated by electrospinning, to support the sustained release of DMOG over two weeks. In vitro experiments indicated that DMOG-loaded PCL mats had significant biological advantages, including: promotion of human umbilical vein endothelial cells (HUVECs) proliferation, migration and production of pro-angiogenic factors; and the stimulation of M2 macrophage polarization, which in-turn promoted macrophage regulation of HUVECs migration and smooth muscle cells (SMCs) contractile phenotype. These beneficial effects were downstream of HIF-1α stabilization in HUVECs and macrophages in normoxic conditions. Our results indicated that DMOG-loaded PCL grafts improved endothelialization, contractile SMCs regeneration, vascularization and modulated the inflammatory reaction of grafts in abdominal artery replacement models, thus promoting vascular regeneration.