A new minimal invasive technique with in-situ stent-graft fenestration for type A aortic dissection.

Background: Aortic surgery successfully improves the prognosis of patients with type A aortic dissection. However, total arch replacement and reconstruction remain challenging. This study presents a new surgical modality, the in-situ stent-graft fenestration (ISSF) technique, for simplifying aortic arch reconstruction and assesses its short-term efficacy and safety in patients with type A aortic dissection. Methods: Data from 177 patients with type A aortic dissection who underwent aortic arch reconstruction were retrospectively analyzed. Sun's procedure was performed in 90 patients and ISSF was performed in the other 87. Results: The in-hospital mortality rate was 7.8% in the Sun's procedure group and 3.4% in the ISSF group (p = 0.357). Compared to the Sun's procedure group, the ISSF group had significantly shorter surgical duration, cardiopulmonary bypass time, circulatory arrest time, mechanical ventilation time, and aortic cross-clamp time (p < 0.05). Additionally, intraoperative blood loss was lower in the ISSF group than in the Sun's procedure group (p < 0.05). Patients who underwent ISSF also had a lower incidence of postoperative complications, including lung injury, renal failure, peripheral nerve injury, and chylothorax, than those who underwent Sun's procedure (p < 0.05). During the 6-month follow-up period after surgery, both groups showed significant improvements in the true lumen diameter of the descending thoracic aorta post-operation compared with the pre-operation measurements; meanwhile, the false lumen diameter decreased (p < 0.05). Conclusions: The ISSF technique appears to be an effective and safe alternative to conventional surgical procedures for patients with type A aortic dissection, with the potential to simplify the procedure, shorten the operation time, and yield satisfactory operative results. However, further investigation is needed to determine its long-term benefits.

Systematic review of the effect of cerebrospinal fluid drainage on outcomes after endovascular type B aortic dissection repair.

OBJECTIVE: The aim of the present systematic review was to determine whether prophylactic use of cerebrospinal fluid drainage (CSFD) contributes to a lower rate of spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD). METHODS: PubMed, Embase, Web of Science and Cochrane Library databases were systematically searched to identify all relevant studies reported before May 7, 2023. A systematic review was conducted in accordance with PRISMA guidelines (PROSPERO registration no. CRD42023441392). The primary outcome was permanent SCI. Secondary outcomes were temporary SCI and 30-day/in-hospital mortality. The data were presented as the pooled event rates (ERs) and 95% confidence intervals (CIs). RESULTS: A total of 1008 studies were screened, of which 34 studies with 2749 patients were included in the present analysis. The mean Downs and Black quality assessment score was 8.71 (range, 5-12). The pooled rate of permanent SCI with prophylactic CSFD was identical to that without prophylactic CSFD (2.0%; 95% CI, 1.0-3.0; P = 0.445). No statistically significant difference was found between the rates of permanent SCI with routine vs. selective prophylactic CSFD (P = 0.596). The pooled rate of temporary SCI was 1.0% (95% CI, 0.00-1.0%). The pooled rate for 30-day or in-hospital mortality was not significantly different (P = 0.525) in patients with prophylactic CSFD (4.0, 95% CI 2.0-6.0) or without prophylactic CSFD (5.0, 95% CI 2.0-7.0). CONCLUSIONS: The systematic review has shown that prophylactic CSFD was not associated with a lower rate of permanent SCI and 30-day or in-hospital mortality after TEVAR for TBAD.

Clinical impact of baseline mitral regurgitation on outcomes after transcatheter aortic valve replacement for severe aortic stenosis.

Objective: The clinical impact of baseline mitral regurgitation (MR) on the outcomes after transcatheter aortic valve replacement (TAVR) is not clear. This study sought to assess the clinical impact of baseline MR on outcomes after TAVR. Methods: The study was a retrospective analysis. Data was from 120 consecutive patients with severe aortic stenosis (AS) undergoing TAVR at our center from June 2018 and July 2020. Clinical outcomes were assessed at 30-day, 1- and 2-year follow-up. Results: The median follow-up was 736.0 (interquartile range, 666.0-965.0) days. Overall survival in patients with nonsignificant and significant baseline MR was not significantly different, while patients from the improved MR group after TAVR demonstrated a significantly higher survival than unchanged or worsened MR group during 2-year follow-up. NYHA functional class had generally improved at 1 year, with only 8.3 % of patients with nonsignificant MR and 17.5 % of patients with significant MR in class III or IV. Patients with improved MR at 1 year after TAVR had a significantly higher LVEF, smaller LVEDD and LVESD than those with unchanged or worsened MR. Among the significant baseline MR group, 70.4 % and 80.0 % of patients had improved to nonsignificant MR at 30-day and 1-year follow-up after TAVR, respectively. Conclusions: Significant baseline MR was not associated with the increased risk of all-cause mortality 2 years after TAVR. Significant baseline MR was improved in most patients at 1 year after TAVR. Patients with unchanged or worsened MR had an increased all-cause mortality.

Effect of transcatheter aortic valve replacement on ascending aorta dilatation rate in patients with tricuspid and bicuspid aortic stenosis.

Objectives: The aim of the present study was to assess the differences between BAV and TAV patients with chronic moderate to severe or severe AS regarding presentation, incidence of TAVR, survival, ascending aorta diameter and dilatation rate before and after TAVR. Methods: The study included 667 consecutive patients with chronic moderate to severe or severe AS from January 2012 and December 2022. Outcomes included all-cause mortality, incidence of TAVR, and ascending aorta diameter and dilatation rate. Results: There were 185 BAV-AS and 482 TAV-AS patients, and BAV-AS patients were younger (67 vs 78 years, P = 0.027). Total follow-up was 4.5 years (IQR: 2.7-8.9 years), 290 patients underwent TAVR, and 165 patients died. The 8-year TAVR incidence was higher in BAV-AS (55% ± 4%) vs TAV-AS (41% ± 5%; P = 0.02). The 8-year survival was higher in BAV-AS (85% ± 6%) vs TAV-AS (71% ± 6%; P < 0.0001) and became insignificant after age adjustment (P = 0.33). The dilatation rate of ascending aorta was significantly faster in BAV-AS patients compared with TAV-AS patients before TAVR. However, the ascending aorta dilatation rate for BAV-AS and TAV-AS patients was not significantly different after TAVR. Conclusions: Compared with TAV-AS, BAV-AS patients were younger and underwent TAVR more frequently, resulting in a considerable survival advantage. After TAVR, ascending aorta dilatation rates were similar in BAV-AS and TAV-AS patients, suggesting an important role of hemodynamics on ascending aorta dilatation in BAV-AS.

Early outcome of simplified total arch reconstruction under mild hypothermia (30-32 °C) with distal aortic perfusion.

OBJECTIVE: We designed a simplified total arch reconstruction (s-TAR) technique which could be performed under mild hypothermia (30-32 °C) with distal aortic perfusion. This study aimed to compare its efficacy of organ protection with the conventional total arch reconstruction (c-TAR). METHODS: We reviewed the clinical data of 195 patients who had ascending aortic aneurysm with extended aortic arch dilation and underwent simultaneous ascending aorta replacement and TAR procedure between January 2018 and December 2022 in our center. 105 received c-TAR under moderate hypothermia (25-28 °C) with circulatory arrest (c-TAR group); rest 90 received s-TAR under mild hypothermia (30-32 °C) with distal aortic perfusion (s-TAR group). RESULTS: The s-TAR group demonstrated shorter CPB time, cross-clamp time and lower body circulatory arrest time compared with the c-TAR group. The 30-day mortality was 2.9% for the c-TAR group and 1.1% for the s-TAR group (P = 0.043). The mean duration of mechanical ventilation was shorter in the s-TAR group. Paraplegia was observed in 4 of 105 patients (3.8%) in the c-TAR group, while no such events were observed in the s-TAR group. The incidence of temporary neurologic dysfunction was significantly higher in the c-TAR group. The incidence of permanent neurologic dysfunction also showed a tendency to be higher in the c-TAR group, without statistical significance. Furthermore, the incidence of reoperation for bleeding were significantly lower in the s-TAR group. The rate of postoperative hepatic dysfunction and all grades of AKI was remarkably lower in the s-TAR group. The 3-year survival rate was 95.6% in the s-TAR group and 91.4% in the c-TAR group. CONCLUSIONS: s-TAR under mild hypothermia (30-32℃) with distal aortic perfusion is associated with lower mortality and morbidity, offering better neurological and visceral organ protection compared with c-TAR.

Supramolecular nanofiber of indomethacin derivative confers highly cyclooxygenase-2 (COX-2) selectivity and boosts anti-inflammatory efficacy.

Herein, we report a facile method for converting carboxylate-containing indomethacin (Idm) into a cyclooxygenase-2 (COX-2) selective inhibitor via the amidation of an unnatural peptide sequence (Nal-Nal-Asp). The resulting indomethacin amides (i.e., Idm-Nal-Nal-Asp) have high selectivity for COX-2, and can self-assemble into a one-component supramolecular hydrogel that acts as a 'self-delivery' system for boosting anti-inflammatory efficacy. Self-assembled Idm-Nal-Nal-Asp hydrogel robustly inhibits COX-2 expression in lipopolysaccharide (LPS)-activated Raw 264.7 macrophages while also exhibits superior anti-inflammatory and antioxidant activities via reactive oxygen species (ROS)-related NF-κB and Nrf2/HO-1 pathways. Moreover, a rabbit model of endotoxin-induced uveitis (EIU) reveals that the Idm-Nal-Nal-Asp hydrogel outperforms clinically used 0.1 wt% diclofenac sodium eye drops in terms of in vivo anti-inflammatory efficacy via topical instillation route. As a rational approach to designing and applying COX-2 selective inhibitors, this work presents a simple method for converting non-selective nonsteriodal anti-inflammatory drugs (NSAIDs) into highly selective COX-2 inhibitors that can self-assemble into supramolecular hydrogel for anti-inflammation applications.

A modified prosthesis eversion technique for proximal anastomosis in ascending aorta replacement.

Background: One of the crucial aspects of ascending aorta replacement is to achieve hemostasis of the proximal anastomosis. This study aimed to describe a modified prosthesis eversion technique for proximal anastomosis in ascending aorta replacement and compare its operative outcomes with the conventional prosthesis eversion technique. Methods: We conducted a retrospective analysis of all consecutive patients who had ascending aortic aneurysm and underwent ascending aorta replacement with the modified or conventional prosthesis eversion technique between January 2019 and December 2022 in our center. Results: A total of 108 patients were included: 55 in the modified group and 53 in the conventional group. The durations of cardiopulmonary bypass, aortic cross-clamping and total operation in the conventional group were longer than those in the modified group. Furthermore, perioperative blood loss and the incidence of re-exploration for bleeding were significantly lower in the modified group. Accordingly, patients in the conventional group accepted more blood transfusion. The modified group had a shorter duration in intensive care unit (ICU) and hospital, and lower total hospitalization costs than those in the conventional group. Conclusions: The modified prosthesis eversion technique is an effective alternative for proximal anastomosis in ascending aorta replacement, with less blood loss, shorter operation time, and lower rate of postoperative complications compared with the conventional technique.

Prognostic impact of new permanent pacemaker implantation following transcatheter aortic valve replacement.

BACKGROUND: Conduction disturbances requiring permanent pacemaker implantation (PPI) are common following transcatheter aortic valve replacement (TAVR). There were conflicting data regarding the impact of new PPI on clinical outcomes after TAVR. OBJECTIVES: The study sought to evaluate the impact of new PPI on clinical outcomes in patients undergoing TAVR. METHODS: This study was a retrospective analysis of prospectively collected data. Data were from 210 consecutive patients without prior PPI who underwent TAVR due to severe symptomatic aortic stenosis at our center between June 2018 and July 2020. Clinical, echocardiographic, and pacing data were assessed at 30-day, 1- and 2-year follow-up. RESULTS: New PPI was required in 35 (16.7%) patients within 30 days after TAVR. The median time from TAVR to PPI was 3 days. The most common indication for PPI was high-degree or complete atrioventricular block. The median follow-up was 798.0 (interquartile range, 669.0-1115.0) days. There were no differences in all-cause mortality (adjusted hazard ratio [HR]: 1.18; 95% confidence interval [CI]: 0.85-2.36; p = 0.415) and cardiovascular mortality (adjusted HR: 0.92; 95% CI: 0.57-1.89; p = 0.609) between groups. However, PPI group had a higher risk of heart failure (HF) rehospitalization (adjusted HR: 1.53; 95% CI: 1.26-2.28; p = 0.027). Echocardiography showed no significant improvement of LVEF over time in patients with PPI. At the latest follow-up, 31.3% of patients exhibited low (≤10%) pacing burdens, whereas 28.1% of patients had near constant (>90%) right ventricular pacing. CONCLUSIONS: New PPI within 30 days following TAVR was not associated with an increased risk of all-cause or cardiovascular mortality. However, patients with PPI had a higher risk of HF rehospitalization and lack of LVEF improvement.

Transfemoral transcatheter aortic valve replacement for pure native aortic regurgitation: one-year outcomes of a single-center study.

BACKGROUND: Evidence about safety and efficacy of transcatheter aortic valve replacement (TAVR) with the Venus A-Valve system (Venus Medtech, Hangzhou, China) remains limited for patients with pure native aortic regurgitation (PNAR). OBJECTIVES: The single-center study sought to report the one-year clinical outcomes of the Venus A-Valve in the treatment of PNAR. METHODS: This study was a retrospective analysis of prospectively collected data. Data was from all consecutive patients who had PNAR and underwent TAVR with the Venus A-Valve system at our center from July 2020 and June 2021. Procedural and clinical outcomes up to one year were analyzed using Valve Academic Research Consortium-2 criteria. RESULTS: A total of 45 consecutive patients with PNAR underwent transfemoral TAVR with the Venus A-Valve system. The Mean age was 73.5 ± 5.5 years and 26.7% were female. All the TAVR procedures were performed via transfemoral access. Implantations were successful in 44 cases (97.8%). Only one patient was converted to surgical aortic valve replacement. No patient died intraoperatively. No second valve was implanted. In-hospital mortality rate was 2.3%. The one-year all-cause mortality rate was 4.7% without cardiovascular related death. No patient had moderate or severe paravalvular leakage during follow-up. At one year, the mean pressure gradient was 8.8 ± 0.9 mmHg, and left ventricular ejection fraction increased to 61.5 ± 3.6%. CONCLUSIONS: This single-center study demonstrated the safety and efficacy of transfemoral TAVR with the Venus A-Valve in the treatment of patients with PNAR.

Simplified total arch reconstruction with a stented graft for extended aortic arch dilation.

Background: Reconstruction of the aortic arch and its three supra-aortic vessels remains a great surgical challenge with postoperative complications. We present a simplified total arch reconstruction with a modified stent graft (s-TAR) and compared its operative outcomes with conventional total arch replacement (c-TAR). Methods: This retrospective analysis of prospectively collected data from all consecutive patients who had ascending aortic aneurysm with extended aortic arch dilation and underwent simultaneous ascending aorta replacement and aortic arch reconstruction with the s-TAR or c-TAR between 2018 and 2021. The indication for intervention was maximum diameter of ascending aorta >55 mm and aortic arch in zone II >35 mm. Results: A total of 84 patients were analyzed: 43 in the s-TAR group and 41 in the c-TAR group. No inter-group differences were found for sex, age, comorbidities, or EuroSCORE II results. All patients were successfully treated with s-TAR or c-TAR, and none died intraoperatively. Cardiopulmonary bypass, selective cerebral perfusion, and lower-body circulatory arrest time were significantly shorter in the s-TAR group, which also had a lower incidence of prolonged ventilation and transient neurologic dysfunction. No patient in either group experienced permanent neurologic dysfunction. The incidence of recurrent laryngeal nerve injury and paraplegia was markedly increased in the c-TAR group; however, no such events were observed in the s-TAR group. Both perioperative blood loss and the incidence of reoperation for bleeding were significantly lower in the s-TAR group. The in-hospital mortality rate was 0% in the s-TAR group and 4.9% in the c-TAR group. The s-TAR group had significantly shorter intensive care unit (ICU) stay and lower total hospitalization costs. Conclusions: The s-TAR technique is a safe and effective alternative for total arch reconstruction with shorter operation time, lower rate of postoperative complications and lower total hospitalization costs compared with c-TAR.

Biocompatible tumor-targeted GQDs nanocatalyst for chemodynamic tumor therapy.

To deal with the complex tumor microenvironment (TME), chemodynamic therapy (CDT) has been developed, which uses nanocatalysts simulating peroxidase to convert high concentration hydrogen peroxide (H2O2) into highly toxic hydroxyl radicals (˙OH) in situ and effectively kills tumor cells. Due to the low catalytic activity of traditional nanocatalysts, the present CDT treatment has to be combined with other anti-tumor therapies, which increases the complexity and uncertainty of the treatment. Thus, developing new nanocatalysts with stable and high enzymatic activity is the key point to CDT treatment. Graphene quantum dots (GQDs) are important metal-free catalysts with intrinsic peroxidase-like activity due to their excellent electron transport performance. Here, we prepare a nitrogen-doped GQD (NGOD) nanocatalyst, which displays much higher peroxidase activity than known metal nanocatalysts. The NGQD nanocatalyst is further grafted with RGDS peptide-modified polyethylene glycol (PEG), which guides the nanocatalyst to the tumor area and increases its circulation time in blood. The as-produced RGDS-PEG@NG nanocatalyst displays stable and high peroxidase activity, which achieves the conversion of H2O2 → ˙OH in the TME. Through an in vivo study it has been observed that RGDS-PEG@NGs obviously inhibit tumor growth without combining with other treatment methods and show excellent biocompatibility, which provides a unique idea for the application of GQDs in CDT.

Enzyme-instructed self-assembly of peptide-drug conjugates in tear fluids for ocular drug delivery.

In vivo self-assembly of small molecules offers an excellent opportunity for targeted and long-term accumulation of a therapeutic agent at the lesion site. Here we demonstrate the strategy of enzyme-instructed self-assembly (EISA) by designing a phosphorylated peptide-drug (IBF-HYD-GFFpY) precursor through the ester bond to release active drugs at the target site. Meanwhile, the in vivo assembly can be achieved by the catalysis of alkaline phosphatase (ALP) in the tear fluid for ocular drug delivery efficiently. The in vitro enzymatic experiments indicate that the dephosphorylation of IBF-HYD-GFFpY occurs firstly with the yield of IBF-HYD-GFFY which subsequently self-assembles into the supramolecular hydrogel to afford sustained drug release over 96 h. In the treatment of lipopolysaccharide (LPS)-activated Raw 264.7 macrophages, IBF-HYD-GFFpY exerts the more potent anti-inflammatory efficacy than that of free ibuprofen (IBF) at the concentration of 200 µM. Moreover, the aqueous solution of IBF-HYD-GFFpY via topical instillation hardly causes ocular irritation, and displays longer precorneal retention compared to the conventional eye drop formulation. In addition, in the in vivo study, a rabbit model of endotoxin-induced uveitis (EIU) evidences the comparable therapeutic efficacy of IBF-HYD-GFFpY eye drops with that of clinically used 0.1 wt% diclofenac (DIC) sodium eye drops by the reduction of macrophage and leukocyte influx. This work, in situ EISA in the tear microenvironment directing in vivo self-assembly of small molecules, may guide a powerful approach for developing enzymatic self-assembled molecules as an efficient delivery system of ocular drugs.

A Rapid Corneal Healing Microneedle for Efficient Ocular Drug Delivery.

Fungal keratitis (FK) remains a serious clinical problem worldwide, so the ultimate goal of the treatment is to develop a minimally invasive, safe, and effective method for ocular drug delivery. Here, a minimally invasive delivery system is reported for treating FK by using a dissolving microneedle (MN)-array patch based on Poly(D,L-lactide) (PLA) and hyaluronic acid (HA). By altering the concentration of PLA, MN patches with excellent properties are modified and optimized. The 30% PLA-HA MN patches penetrate the corneal epithelial layer reversibly with no apparent ocular irritation as well as a short recovery time of less than 12 h, and increase the residence time by 2.5 h in the conjunctival sac, thereby offering higher drug bioavailability. Remarkably, the rabbit model of FK shows that the topical MN(+) patch medication exerts superior therapeutic effects compared with the conventional eye drop formulation, and also presents comparable therapeutic efficacy with that of the clinical mainstay strategy (i.e., intrastromal injection). Therefore, the MN patch, acting as an ocular drug delivery system with high efficacy and ability of rapid corneal healing, promises a cost-effective household solution for the treatment of FK, which may also lead to a new approach for treating FK in clinics.

A Novel Indomethacin-Tripeptide Hydrogel for Inhibiting Ocular Inflammation.

A highly efficient method for constructing indomethacin-peptide conjugates was developed using the natural amino acid tyrosine (Y) as the anchor for indomethacin (Idm). With pH = 6, Idm-YEE conjugate self-assembled in a low critical micelle concentration (CMC, 0.037 mg/mL) and formed a transparent hydrogel (0.4 wt%). The formed Idm-YEE hydrogel presented sustained drug release of indomethacin with a maximum of 40% during first 24 hours, which was superior to the reported Idm-containing supramolecular hydrogel systems. As kept at 4 °C, the Idm-YEE hydrogel showed good storage stability up to 30 days without obvious hydrolysis. As shown by MTT assay, the Idm-YEE hydrogel exhibited good cell compatibility against retinal pigment epithelial cells (ARPE-19) and Human corneal epithelial cells (HCEC). Ocular irritation test (i.e., clinical observations, fluorescein staining and H&E histological analysis) results showed good integrity of corneal architecture and no edema after Idm-YEE hydrogel treatment, which proved its good ocular biocompatibility. Besides, the LPS-stimulated levels of key inflammatory mediators, including NO, PGE2 and IL-6, were greatly reduced by Idm-YEE hydrogel even in a low concentration (50 µM) in Raw264.7 cells, which indicated its comparable in vitro anti-inflammatory activity to indomethacin. Furthermore, the therapeutic efficacy of Idm-YEE hydrogel was evaluated in endotoxin-induced uveitis (EIU) rabbit model. By treating with dm-YEE hydrogel, the rabbit eyes had significantly lowered inflammation and exudation in the anterior chamber. The results of histological analysis, clinical score, inflammatory cell counts, aqueous protein concentration and immunohistochemical staining also demonstrated its good in vivo therapeutic activity towards ocular inflammation. Therefore, with good ocular biocompatibility and comparable anti-inflammatory effect towards ocular inflammation, the novel indomethacin-tripeptide hydrogel (Idm-YEE) developed in this work provides a potential treatment for anterior uveitis.

In Vivo Regenerable Cerium Oxide Nanozyme-Loaded pH/H2O2-Responsive Nanovesicle for Tumor-Targeted Photothermal and Photodynamic Therapies.

Photodynamic therapy (PDT) and photothermal therapies (PTTs) are both promising strategies for effective tumor therapy. However, the absence of O2 at tumor sites hinders the sustained response of photosensitizers. Here, we develop a recycled cerium oxide (CeO2) catalase nanozyme-loaded hyaluronic acid nanovesicle to address the hypoxic tumor microenvironments and targeted delivery of the photosensitizers [indocyanine green (ICG)] to tumors. A polysaccharide complex effectively modifies the surface of a polyethylenimine phenylboronic acid nanostructure to achieve the CeO2 nanozyme-loading nanovesicles that exhibit both tumor-targeted enhancement and an improved hypoxic microenvironment. Also, the hydrogen peroxide responsiveness and acid-sensitive cleavage of phenylboronic acid specifically disintegrate the ICG/nanozyme coloaded nanovesicles in the tumor microenvironment. The in vitro synergistic tests and tumor suppression rate tests indicated that the cerium oxide nanozyme significantly improves the outcomes of PDT via cerium-element valence state recycling and hypoxia improvement, thus enhancing the tumor suppression efficiency. This pH/H2O2-responsive nanozyme/ICG codelivery system provides a good carrier model for improving the tumor microenvironment and increasing the efficiency of tumor-targeted PTT and PDT therapies.

Effects of Terminal Motif on the Self-Assembly of Dexamethasone Derivatives.

Tailoring the terminal motif of molecules including drugs might significantly affect their self-assembly tendency in aqueous solution, thus providing a rational strategy to modulate its macroscopic characteristics of supramolecular assembly. A model drug of dexamethasone (Dex) was esterified by different fatty acids [succinic acid (SA), glutaric acid (GA), and adipic acid (AA)] and aromatic acid [phthalic acid (PA)] to generate a series of Dex derivatives. Aqueous solution of Dex-SA, Dex-GA, and Dex-AA turned into hydrogel spontaneously after a period time of incubation (24, 48, and 72 h, respectively) via the auto-hydrolytic strategy, while aqueous solution of Dex-PA did not result in hydrogelation during 3 days of incubation. Aqueous solutions of Dex-SA, Dex-GA, and Dex-AA underwent apparent hydrolysis (10.73 ± 0.64%, 15.17 ± 2.24%, and 17.29 ± 1.39%, respectively), while Dex-PA exhibited a minimal hydrolysis (<1%) in a period of 28 days study, as indicated by in vitro hydrolytic test. Morphological observation showed that the hydrogel formed by Dex-SA was composed of uniform nanofibers, while hydrogels formed by Dex-GA, and Dex-AA were derived from irregular particles. The mechanical strength of hydrogel formed by Dex-SA was much bigger than that of hydrogels formed by Dex-GA and Dex-AA, as indicated by rheological test. Moreover, the acylation of Dex did not compromise its potent anti-inflammatory activity in a lipopolysaccharide (LPS)-activated RAW 264.7 macrophage.

Mucoadhesive dexamethasone-glycol chitosan nanoparticles for ophthalmic drug delivery.

Self-assembly of drug-polysacrrides conjugates forming nanostructures provides a simple and promising strategy for the extension of precorneal retention and enhancement of corneal permeability. In the present study, a series of dexamethasone-glycol chitosan (Dex-GCS) conjugates were synthesized and thoroughly characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and ultraviolet-visible (UV-Vis) spectroscopy. The resulting Dex-GCS conjugates were able to self-assemble into nanoparticles spontaneously with particle sizes in the range of 277-289 nm and a positive charge of approximately +15 mV. Roughly spherical nanoparticles were observed by transmission electron microscopy (TEM). The in vitro mucoadhesive properties of Dex-GCS nanoparticles were evaluated by recording the variations in the zeta potential after incubation with different concentrations of mucin. In vitro release studies performed in phosphate-buffered saline (PBS, pH = 7.4) indicated progressive Dex release up to 8 h, followed by a plateau up to 48 h. Dex-GCS nanoparticles caused slight cytotoxicity against L929, HCEC and RAW 264.7 cells after 24 h of incubation and displayed a nearly identical anti-inflammatory efficacy to dexamethasone sodium phosphate (Dexp) in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. More importantly, the proposed Dex-GCS nanoparticles showed good ocular tolerance and provided a relatively longer precorneal duration compared with that of the aqueous solution formulation, which suggested that the self-assembled Dex-GCS nanoparticle might be a promising candidate for ophthalmic drug delivery.

Thermosensitive glycol chitosan-based hydrogel as a topical ocular drug delivery system for enhanced ocular bioavailability.

In the present study, we developed and evaluated an in situ gelling system based on hexanoyl glycol chitosan (H-GCS) for enhanced ocular bioavailability. An aqueous solution of H-GCS exhibited a typical sol-gel transition at 32 °C. The formed H-GCS hydrogel was characterized by rheology and scanning electron microscopy (SEM). H-GCS had minimal in vitro cytotoxicity against L-929 and HCEC cells over a concentration range of 0-0.8 mg/mL. Additionally, the H-GCS hydrogel exhibited good ocular tolerance and biocompatibility after a single instillation. Moreover, H-GCS hydrogel significantly prolonged the precorneal retention of fluorescein sodium compared with its aqueous solution. An in vivo pharmacokinetic study demonstrated that the levofloxacin-loaded H-GCS hydrogel could provide a significantly higher Cmax and AUC0-12h compared with the levofloxacin aqueous solution, thus increasing ocular bioavailability. Overall, the proposed H-GCS hydrogel acts as an in situ gelling system that might represent a promising vehicle for topical ocular drug delivery.

PTEN-mediated mitophagy and APE1 overexpression protects against cardiac hypoxia/reoxygenation injury.

Autophagy plays a critical role in cardiac hypoxia/reoxygenation (H/R). Studies indicated that the phosphatase and tensin homolog (PTEN) influences level of autophagy. This study aims to explore the role of PTEN mediating a specific autophagy, mitophagy, in cardiac H/R injury. H9c2 cells were cultured and suffered hypoxia and reoxygenation treatment. To inhibit function of PTEN protein, bpv (phen) was added into medium throughout the process of H/R injury. In addition, we overexpressed the apurinic/apyrimidinic endonuclease 1 (APE1) in H/R-injured H9c2 cells. Then the cell viability, apoptosis, and release of Cytochrome C were determined through CCK-8 assay, flow cytometry, and western blotting, respectively. The results indicated that H/R significantly induced autophagy, as identified by an increased level of microtubule-associated protein 1 light chain 3 beta (LC3B) and a decreased level of sequestosome 1 (P62). After stimulation of bpv (phen), PTEN-induced putative kinase protein 1 (PINK1)/Parkin-mediated mitophagy was inhibited, while apoptosis and releases of Cytochrome C were both significantly increased, indicating an exacerbated H/R injury. Furthermore, the overexpression of APE1 attenuated the apoptosis and releases of Cytochrome C induced by H/R injury, and promoted PINK1/Parkin-mediated mitophagy. Our findings provide an insight into the PTEN and APE1 overexpression protects against cardiac hypoxia/reoxygenation injury, which may be through inducing the PINK1/Parkin-mediated mitophagy.

Stimulus-Responsive Hydrogel for Ophthalmic Drug Delivery.

Blindness and vision impairment are major global health problems. Effective ophthalmic drug delivery poses a significant challenge because of protective physiological barriers and various biological clearance mechanisms that result in extremely low ocular bioavailability. Over the past several decades, several safe and effective ophthalmic drug delivery approaches have been promoted to combat these problems and to improve ocular bioavailability. Among these approaches, the stimulus-responsive hydrogel for topical drug delivery has gained increasing attention because of its prolonged drug retention at the local site and enhanced ocular bioavailability. This review summarizes and presents recent advances and perspectives of a stimulus-responsive hydrogel for ophthalmic drug delivery.