Ultrasound-targeted microbubble destruction (UTMD) has recently drawn considerable attention in biomedicine applications due to its great potential to locally enhance gene delivery. However, conventional microbubbles have a microscale particle size and polydisperse particle size distribution, which makes it difficult for them to directly come into contact with tumor cells and to efficiently deliver therapeutic genes via ultrasound cavitation effects. In the current study, we developed a kind of novel cationic biosynthetic nanobubble (CBNB) as an ultrasonic gene delivery carrier through coating PEI on the surface of these biosynthetic nanobubbles (BNBs). The BNBs, produced from an extremely halophilic archaeon (Halobacterium NRC-1), possess a nanoscale size and can produce stable contrast signals both in vitro and in vivo. Surface modification with PEI polymer greatly increased the DNA loading capability of BNBs, leading to significantly improved gene transfection efficiency when combining with ultrasound. To our knowledge, this is the first report to apply biosynthetic bubbles as non-viral gene carriers which can effectively deliver genes into tumor cells with the aid of ultrasound cavitation. Our study provides a powerful tool for image-guided and efficient gene delivery using biosynthetic nanoscale contrast agents.

Background: Valvular dysfunction is a common complication in patients with bicuspid aortic valves (BAV). The aim of this study was to determine the relationship between BAV morphology patterns and valve dysfunction.Methods: We searched the PubMed, The Cochrane Library, Web of Science, and CNKI until May 31, 2020, to identify all studies investigating the morphology of BAV and valvular dysfunction, and data were extracted according to the Preferred Reporting Items for Systematic reviews and Meta‐Analyses (PRISMA). Data were analyzed using Stata 15.1 software. The additional characteristics (gender, mean age) were collected to perform a meta‐regression analysis.Results: Thirteen studies on BAV‐RL (n = 2002) versus BAV‐RN (n = 1254) and raphe (n = 4001) versus without raphe (n = 673) were included. The BAV‐RL patients showed a higher incidence of aortic regurgitation than BAV‐RN patients (OR = 1.46; 95% CI: 1.12 to 1.90, p = .005), while the BAV‐RL patients showed a lower incidence of aortic stenosis than BAV‐RN patients (OR = 0.66, 95% CI: 0.58 to 0.76, p = .000); BAV patients with raphe presents a higher incidence of aortic regurgitation than those without raphe (OR = 1.95, 95% CI: 1.12–3.39, p = .017). No differences were found between raphe and without raphe group in the incidence of aortic stenosis (OR = 0.97, 95% CI: 0.53 to 1.76, p = .907). Mean age and gender had no influence on observed differences.Conclusions: Our results confirmed a relationship between different BAV phenotypes and aortic valve dysfunction. BAV‐RL and BAV with raphe are more likely to develop aortic regurgitation, while patients with BAV‐RN present a higher possibility to develop aortic stenosis.

Pulmonary microvascular endothelial cell (PMVEC) apoptosis is the initial stage of adult pulmonary hypertension (PH), which involves high pulmonary arterial pressure and pulmonary vascular remodeling. However, the mechanism regulating PMVEC apoptosis and its involvement in the early stages of neonatal hypoxic PH (HPH) pathogenesis are currently unclear. The present study aimed to investigate the effects of heat shock protein 70 (HSP70) on hypoxia‑induced apoptosis in PMVECs. PMVECs isolated from neonatal Sprague‑Dawley rats were transfected with lentivirus with or without HSP70, or treated with the synthetic HSP70 inhibitor N‑formyl‑3,4‑methylenedioxy‑benzylidene-g-butyrolactam under hypoxic conditions (5% O₂) for 24, 48 or 72 h. PMVEC apoptosis was evaluated by performing flow cytometry and mitochondrial membrane potential (MMP) assays. The expression levels of HSP70, hypoxia‑inducible factor‑1α (HIF‑1α) and apoptosis‑associated proteins were determined by conducting reverse transcription‑quantitative PCR and western blotting. Following 24, 48 or 72 h of hypoxia, the apoptotic rates of PMVECs were significantly elevated compared with cells under normoxic conditions. The MMP was significantly reduced, whereas the mRNA and protein expression levels of HIF‑1α, cytochrome c (cyt C), caspase‑3 and HSP70 were enhanced by hypoxia compared with those under normoxic conditions. Additionally, the mRNA and protein expression levels of B‑cell lymphoma 2 (Bcl‑2) were significantly downregulated in the hypoxia group compared with those in the normoxia group. In hypoxic PMVECs, HSP70 overexpression decreased the apoptotic rate and the expression levels of cyt C, downregulated the expression levels of caspase‑3 and HIF‑1α, and increased the MMP and the expression levels of Bcl‑2. HSP70 inhibition resulted in the opposite outcomes compared with those of HSP70 overexpression. Therefore, the results of the present study suggested that HSP70 may inhibit mitochondrial pathway‑mediated apoptosis in isolated neonatal rat PMVECs in early‑stage hypoxia, which may be associated with HSP70‑mediated HIF‑1α downregulation. Overall, HSP70 may be protective against neonatal HPH through the HSP70/HIF‑1α pathway.

This paper aims to study the thrombolytic effect of low-frequency ultrasound combined with targeted urokinase-containing microbubble contrast agents on treatment of thrombosis in rabbit femoral artery; and to determine the optimal combination of parameters for achieving thrombolysis in this model. A biotinylated-avidin method was used to prepare microbubble contrast agents carrying urokinase and Arg-Gly-Asp-Ser (RGDS) peptides. Following femoral artery thrombosis in New Zealand white rabbits, microbubble contrast agents were injected intravenously, and ultrasonic exposure was applied. A 3 × 2 × 2 factorial table was applied to categorize the experimental animals based on different levels of combination of ultrasonic frequencies (Factor A: 1.6 MHz, 2.2 MHz, 2.8 MHz), doses of urokinase (Factor B: 90,000 IU/Kg, 180,000 IU/Kg) and ultrasound exposure time (Factor C: 30 min, 60 min). A total of 72 experimental animals were randomly divided into 12 groups (n = 6/group). Doppler techniques were used to assess blood flow in the distal end of the thrombotic femoral artery during the 120 minutes thrombolysis experiment. The rate of recanalization following thrombolysis was calculated, and thrombolytic efficacy was evaluated and compared. The thrombolytic recanalization rate for all experimental subjects after thrombolytic therapy was 68.1%. The optimal parameters for thrombolysis were determined to be 1) an ultrasound frequency of 2.2 MHz and 2) a 90,000 IU/kg dose of urokinase. Ultrasound exposure time (30 min vs. 60 min) had no significant effect on the thrombolytic effects. The combination of local low-frequency ultrasound radiation, targeted microbubbles, and thrombolytic urokinase induced thrombolysis of femoral artery thrombosis in a rabbit model. The ultrasonic frequency of 2.2 MHz and urokinase dose of 90,000 IU/kg induced optimal thrombolytic effects, while the application of either 30 min or 60 min of ultrasound exposure had similar effects.