Novel gradient bimetallic hydrogel promotes tendon-to-bone interface reconstruction by synchronous regeneration.

Background: Large bone defects resulting from trauma and diseases still a great challenge for the surgeons. Exosomes modified tissue engineering scaffolds are one of the promising cell-free approach for repairing the defects. Despite extensive knowledge of the variety kinds of exosomes promote tissue regeneration, little is known of the effect and mechanism for the adipose stem cells-derived exosomes (ADSCs-Exos) on bone defect repair. This study aimed to explore whether ADSCs-Exos and ADSCs-Exos modified tissue engineering scaffold promotes bone defects repair.Material/Methods: ADSCs-Exos were isolated and identified by transmission electron microscopy nanoparticle tracking analysis, and western blot. Rat bone marrow mesenchymal stem cells (BMSCs) were exposed to ADSCs-Exos. The CCK-8 assay, scratch wound assay, alkaline phosphatase activity assay, and alizarin red staining were used to evaluate the proliferation, migration, and osteogenic differentiation of BMSCs. Subsequently, a bio-scaffold, ADSCs-Exos modified gelatin sponge/polydopamine scaffold (GS-PDA-Exos), were prepared. After characterized by scanning electron microscopy and exosomes release assay, the repair effect of the GS-PDA-Exos scaffold on BMSCs and bone defects was evaluated in vitro and in vivo.Results: The diameter of ADSCs-exos is around 122.1 nm and high expressed exosome-specific markers CD9 and CD63. ADSCs-Exos promote the proliferation migration and osteogenic differentiation of BMSCs. ADSCs-Exos was combined with gelatin sponge by polydopamine (PDA)coating and released slowly. After exposed to the GS-PDA-Exos scaffold, BMSCs have more calcium nodules with osteoinductive medium and higher expression the mRNA of osteogenic related genes compared with other groups. The quantitative analysis of all micro-CT parameters showed that GS-PDA-Exos scaffold promote new bone formed in the femur defect model in vivo and confirmed by histological analysis.Conclusion: This study demonstrates the repair efficacy of ADSCs-Exos in bone defects, ADSCs-Exos modified scaffold showing a huge potential in the treatment of large bone defects.

Background: Currently, the perioperative care of fracture patients is compromised due to the outbreak of COVID-19 in China and the world. This study aims to assess the clinical features of fracture patients at our hospital during the COVID-19 outbreak and formulate the medical steps to ensure the effective treatment of fracture patients with minimal risk of infection to healthcare workers. Methods: One hundred twelve patients with different fractures that were admitted to the orthopedics department of our hospital from January 24 to March 9 in 2020 were reviewed. Data including age, gender, injury location, admission time, operation time, discharge time were compared with fracture patients from the same period in 2019 Results: Compared to the same period in 2019, there is a 42% decrease in the number of fracture patients in 2020. Specifically, the incidences of forearm, thigh, hand, and foot fractures have increased during the COVID-19 outbreak, while other parts are less affected. The time from injury to hospitalization, the surgery wait time and time of discharge after surgery for patients with hip fractures were 2.9±7.1, 2.0±1.7 and 7.7±4.0 days respectively in 2019, which changed to 2.0±5.0, 4.5±4.0 and 10.6±4.2 days in 2020. Following the orthopedic treatment regimen followed at our hospital, all patients had non-life-threatening limb fractures. Six patients were operated in a negative pressure room, and emergency screening was completed for six patients. No patients were positive for COVID-19, and all were discharged safely without infection or other serious complications. Conclusions: Hip fractures are highly prevalent during this epidemic. However, mandatory screening delays surgery by more than 48 hours. The orthopedic department should prioritize screening of emergency patients to minimize the risk of infection among other patients and medical personnel.

Inspired by the imbalance between extrinsic and intrinsic tendon healing, this study fabricated a new biofilter scaffold with a hierarchical structure based on a melt electrowriting technique. The outer multilayered fibrous structure with connected porous characteristics provides a novel passageway for vascularization and isolates the penetration of scar fibers, which can be referred to as a biofilter process. In vitro experiments found that the porous architecture in the outer layer can effectively prevent cell infiltration, whereas the aligned fibers in the inner layer can promote cell recruitment and growth, as well as the expression of tendon-associated proteins in a simulated friction condition. It was shown in vivo that the biofilter process could promote tendon healing and reduce scar invasion. Herein, this novel strategy indicates great potential to design new biomaterials for balancing extrinsic and intrinsic healing and realizing scarless tendon healing.

Objective: Fluid extravasation is a potentially dangerous complication associated with shoulder arthroscopy. Most relevant studies have involved respiratory system, while the primary purpose was to reveal the effects of the fluid extravasation on cardiovascular system and postoperative function.Methods: The clinical data of 92 patients was retrospective analyzed, in which 84 cases with rotator cuff injury, three cases with shoulder instability, three cases with fractures of the greater tuberosity of the humerus, and two cases with frozen shoulder. All the patients were undergoing shoulder arthroscopy. The relationship between the basic information of the patients and cardiac index (CI) or pulse pressure variation (PPV) were evaluated by linear regression analysis. The change of CI or PPV at different states were evaluated by the one‐way analysis of variance. The liquid retention (TR) and postoperative clinical outcomes was analyzed using linear regression.Results: The preoperative CI was affected by anesthesia status and body position, while PPV was not affected. Multivariate mixed‐effects model analysis of CI found that there was a statistically significant difference in groups of older than 55 years old and those with obesity (BMI > 24). After the operation, the retention of irrigation fluid significantly influenced the circumference of the deltoid (P < 0.001 (95%CI: [0.30, 1.00])), but not on the circumference of the deltoid, neck, and arm. The multivariate analysis of the American Shoulder and Elbow Surgery (ASES) scores at 3 and 6 months after surgery showed that the fluid retention volume was correlated with the ASES score at 3 months after surgery, especially when the retention volume was greater than 2 L (P = 0.001 (95%). %CI: [−12.49, −3.22]).Conclusion: The retention of irrigation fluid after shoulder arthroscopic surgery causes swelling of local limbs, and has an effect on peripheral blood vessels, which is mainly reflected in its influence on PPV and the postoperative function. Therefore, surgeons need to improve their surgical technique, shorten the operation time and reduce fluid retention.