Regulation of angiogenesis by signal sequence-derived peptides.

Background: The neuropilin-like, Discoidin, CUB and LCCL domain containing 2 (DCBLD2) is a transmembrane protein with an unusually long signal sequence (SS) composed of N-terminal (N) and C-terminal (C) subdomains, separated by a transition (tra) subdomain. DCBLD2 interacts with VEGFR-2 and regulates VEGF-induced endothelial cell signaling, proliferation and migration, as well as angiogenesis. The exact mechanisms by which DCBLD2 interacts with VEGFR2 to modulate VEGF signaling remain unclear. Methods: Searching for VEGFR2 interacting DCBLD2 domains, we generated various constructs containing different DCBLD2 domain combinations and conducted co-immunoprecipitation and signaling studies in HEK 293T and endothelial cells. Several peptides were synthesized based on the identified domain, and their effect on VEGF signaling was assessed in vitro in cell culture and in vivo using matrigel plug and corneal micropocket assays. The effect of the lead peptide was further evaluated using a murine hindlimb ischemia model. Results: DCBLD2 SS interacted with VEGFR2 and promoted VEGF signaling. SS was not cleaved in the mature DCBLD2 and its hydrophobic transmembrane 'traC' segment, but not the 'N' subdomain, was involved in DCBLD2-VEGFR2 interaction. The smallest unit in DCBLD2 SS that interacts with VEGFR2 was the L5VL5 sequence. Even after the central valine was removed, the L10 sequence mimicked the DCBLD2 SS traC's effect on VEGF-signaling, while shorter or longer poly-leucine sequences were less effective. Finally, a synthetic traC peptide enhanced VEGF signaling in vitro, promoted VEGF-induced angiogenesis in vivo, and improved blood flow recovery following hindlimb ischemia. Conclusion: DCBLD2 SS along with its derivative peptides can promote VEGFR2 signaling and angiogenesis. Synthetic peptides based on DCBLD2 SS hold promise as therapeutic agents for regulating angiogenesis. Importantly these findings refine the traditional view of signal sequences as mere targeting elements, revealing a role in cellular signaling. This opens new avenues for research and therapeutic strategies.

Multimodality Imaging of Aortic Valve Calcification and Function in a Murine Model of Calcific Aortic Valve Disease and Bicuspid Aortic Valve.

Calcific aortic valve disease (CAVD) is a prevailing disease with increasing occurrence and no known medical therapy. Dcbld2-/- mice have a high prevalence of bicuspid aortic valve (BAV), spontaneous aortic valve calcification, and aortic stenosis (AS). 18F-NaF PET/CT can detect the aortic valve calcification process in humans. However, its feasibility in preclinical models of CAVD remains to be determined. Here, we sought to validate 18F-NaF PET/CT for tracking murine aortic valve calcification and leveraged it to examine the development of calcification with aging and its interdependence with BAV and AS in Dcbld2-/- mice. Methods: Dcbld2-/- mice at 3-4 mo, 10-16 mo, and 18-24 mo underwent echocardiography, 18F-NaF PET/CT (n = 34, or autoradiography (n = 45)), and tissue analysis. A subset of mice underwent both PET/CT and autoradiography (n = 12). The aortic valve signal was quantified as SUVmax on PET/CT and as percentage injected dose per square centimeter on autoradiography. The valve tissue sections were analyzed by microscopy to identify tricuspid and bicuspid aortic valves. Results: The aortic valve 18F-NaF signal on PET/CT was significantly higher at 18-24 mo (P < 0.0001) and 10-16 mo (P < 0.05) than at 3-4 mo. Additionally, at 18-24 mo BAV had a higher 18F-NaF signal than tricuspid aortic valves (P < 0.05). These findings were confirmed by autoradiography, with BAV having significantly higher 18F-NaF uptake in each age group. A significant correlation between PET and autoradiography data (Pearson r = 0.79, P < 0.01) established the accuracy of PET quantification. The rate of calcification with aging was significantly faster for BAV (P < 0.05). Transaortic valve flow velocity was significantly higher in animals with BAV at all ages. Finally, there was a significant correlation between transaortic valve flow velocity and aortic valve calcification by both PET/CT (r = 0.55, P < 0.001) and autoradiography (r = 0.45, P < 0.01). Conclusion: 18F-NaF PET/CT links valvular calcification to BAV and aging in Dcbld2-/- mice and suggests that AS may promote calcification. In addition to addressing the pathobiology of valvular calcification, 18F-NaF PET/CT may be a valuable tool for evaluation of emerging therapeutic interventions in CAVD.

A novel endoscopic approach for management of hutch diverticulum concomitant vesicoureteral reflux with dextranomer/hyaluronic acid copolymer injection.

INTRODUCTION: There are various treatment options for symptomatic bladder diverticulum, including robotic-assisted laparoscopic bladder diverticulectomy, open and endoscopic techniques. But, to date, the optimal surgical technique remains unclear. OBJECTIVE: To present the preliminary long-term follow-up results of a novel technique of dextranomer/hyaluronic acid copolymer (Deflux) plus autologous blood injection for correction of hutch diverticulum in patients with concomitant vesicoureteral reflux (VUR). PATIENT AND METHOD: We retrospectively reviewed four patients who had hutch diverticulum with concomitant VUR and had undergone submucosal Deflux following autologous blood injection. Patients with neurogenic bladder, posterior urethral valve, or voiding dysfunction were excluded from the study. Success was defined as the resolution of the diverticulum, hydronephrosis, and hydroureter on ultrasonography at a 3-month follow-up and long-term symptom-free period. RESULTS: Four patients with hutch diverticula were included. The median age at the time of surgery was 6.1 (range 3-8) years. Three of them had unilateral VUR, and one had bilateral VUR. During the procedure, a mean of 0.625 ml Deflux plus a mean of 1.25 ml autologous blood were injected submucosally for correction of VUR. Additionally, a mean of 1.62 ml Deflux plus a mean of 1.75 ml autologous blood were injected submucosally to occlude the diverticulum. The median follow-up was 4.6 (range 4-8) years. This method had excellent success in all patients in the current study with no postoperative complications such as febrile urinary tract infection, or diverticulum, hydroureter, or hydronephrosis in follow-up ultrasounds. CONCLUSIONS: Submucosal injection of Deflux plus autologous blood injection can be a successful endoscopic intervention for treatments of hutch diverticulum in patients with concomitant VUR. Deflux injection can be a simple and cost-effective technique.

Meatal stenosis following three types of circumcision with frenular artery preservation (FAP), the Plastibell device (PD), and frenular artery ligation (FAL): a long-term follow-up.

BACKGROUND: Despite the simplicity of male circumcision, complications occur frequently. Post-circumcision meatal stenosis is a concerning complication that might require several interventions. AIM: This study aims to evaluate the incidence of meatal stenosis in long-term follow-up, following three common circumcision methods: frenular artery preservation, frenular ligation, and the Plastibell device. METHODS: This study is the continuation of the previous randomized clinical trial, the preliminary abstract of which has been accepted in the annual meeting of the American Urological Association in 2011. However, in this paper, we only included the patients with results of long-term follow-up. Patients were followed for a median of 11 years (range, 7-17). Follow-ups were recorded by evaluation of meatus and signs and symptoms of meatal stenosis. RESULTS: Two hundred six boys (80 neonates and 126 non-neonates) at the time of procedure were included in this study. The circumcision was conducted on 23.3% (48/206) of boys with the Plastibell device (PD) and 39.3% (81/206) of cases with frenular artery preservation (FAP) and 37.4% (77/206) of cases with frenular artery ligation (FAL). Meatal stenosis presented in 13 children during follow-up. Considering the three methods of circumcision, a significant difference in the incidence of meatal stenosis among the types of circumcisions was observed (6.3% in PD and 1.2% in FAP, 11.7% in FAL, P = 0.026). CONCLUSION: The present study revealed that the technique preserving the frenular artery is associated with a significantly lower incidence of meatal stenosis. Hence, the FAP is the recommended technique for circumcision as compared to two other methods.

Decellularization in Tissue Engineering and Regenerative Medicine: Evaluation, Modification, and Application Methods.

Reproduction of different tissues using scaffolds and materials is a major element in regenerative medicine. The regeneration of whole organs with decellularized extracellular matrix (dECM) has remained a goal despite the use of these materials for different purposes. Recently, decellularization techniques have been widely used in producing scaffolds that are appropriate for regenerating damaged organs and may be able to overcome the shortage of donor organs. Decellularized ECM offers several advantages over synthetic compounds, including the preserved natural microenvironment features. Different decellularization methods have been developed, each of which is appropriate for removing cells from specific tissues under certain conditions. A variety of methods have been advanced for evaluating the decellularization process in terms of cell removal efficiency, tissue ultrastructure preservation, toxicity, biocompatibility, biodegradability, and mechanical resistance in order to enhance the efficacy of decellularization methods. Modification techniques improve the characteristics of decellularized scaffolds, making them available for the regeneration of damaged tissues. Moreover, modification of scaffolds makes them appropriate options for drug delivery, disease modeling, and improving stem cells growth and proliferation. However, considering different challenges in the way of decellularization methods and application of decellularized scaffolds, this field is constantly developing and progressively moving forward. This review has outlined recent decellularization and sterilization strategies, evaluation tests for efficient decellularization, materials processing, application, and challenges and future outlooks of decellularization in regenerative medicine and tissue engineering.

Remdesivir: A beacon of hope from Ebola virus disease to COVID-19.

Since the emergence of coronavirus disease 2019 (Covid-19), many studies have been performed to characterize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and find the optimum way to combat this virus. After suggestions and assessments of several therapeutic options, remdesivir (GS-5734), a direct-acting antiviral drug previously tested against Ebola virus disease, was found to be moderately effective and probably safe for inhibiting SARS-CoV-2 replication. Finally, on 1 May 2020, remdesivir (GS-5734) was granted emergency use authorization as an investigational drug for the treatment of Covid-19 by the Food and Drug Administration. However, without a doubt, there are challenging days ahead. Here, we provide a review of the latest findings (based on preprints, post-prints, and news releases in scientific websites) related to remdesivir efficacy and safety for the treatment of Covid-19, along with covering remdesivir history from bench-to-bedside, as well as an overview of its mechanism of action. In addition, active clinical trials, as well as challenging issues related to the future of remdesivir in Covid-19, are covered. Up to the date of writing this review (19 May 2020), there is one finished randomized clinical trial and two completed non-randomized studies, in addition to some ongoing studies, including three observational studies, two expanded access studies, and seven active clinical trials registered on the clinicaltrials.gov and isrctn.com websites. Based on these studies, it seems that remdesivir could be an effective and probably safe treatment option for Covid-19. However, more randomized controlled studies are required.