The Role of HIF-1α in Bone Regeneration: A New Direction and Challenge in Bone Tissue Engineering.

The process of repairing significant bone defects requires the recruitment of a considerable number of cells for osteogenesis-related activities, which implies the consumption of a substantial amount of oxygen and nutrients. Therefore, the limited supply of nutrients and oxygen at the defect site is a vital constraint that affects the regenerative effect, which is closely related to the degree of a well-established vascular network. Hypoxia-inducible factor (HIF-1α), which is an essential transcription factor activated in hypoxic environments, plays a vital role in vascular network construction. HIF-1α, which plays a central role in regulating cartilage and bone formation, induces vascular invasion and differentiation of osteoprogenitor cells to promote and maintain extracellular matrix production by mediating the adaptive response of cells to changes in oxygen levels. However, the application of HIF-1α in bone tissue engineering is still controversial. As such, clarifying the function of HIF-1α in regulating the bone regeneration process is one of the urgent issues that need to be addressed. This review provides insight into the mechanisms of HIF-1α action in bone regeneration and related recent advances. It also describes current strategies for applying hypoxia induction and hypoxia mimicry in bone tissue engineering, providing theoretical support for the use of HIF-1α in establishing a novel and feasible bone repair strategy in clinical settings.

Physical, mechanical, and biological properties of collagen membranes for guided bone regeneration: a comparative in vitro study.

BACKGROUND: To provide a reference for clinical selection of collagen membranes by analyzing the properties of three kinds of collagen membranes widely used in clinics: Bio-Gide membrane from porcine dermis (PD), Heal-All membrane from bovine dermis (BD), and Lyoplant membrane from bovine pericardium (BP). METHODS: The barrier function of three kinds of collagen membranes were evaluated by testing the surface morphology, mechanical properties, hydrophilicity, and degradation rate of collagen membranes in collagenase and artificial saliva. In addition, the bioactivity of each collagen membrane as well as the proliferation and osteogenesis of MC3T3-E1 cells were evaluated. Mass spectrometry was also used to analyze the degradation products. RESULTS: The BP membrane had the highest tensile strength and Young's modulus as well as the largest water contact angle. The PD membrane exhibited the highest elongation at break, the smallest water contact angle, and the lowest degradation weight loss. The BD membrane had the highest degradation weight loss, the highest number of proteins in its degradation product, the strongest effect on the proliferation of MC3T3-E1 cells, and the highest expression level of osteogenic genes. CONCLUSIONS: The PD membrane is the best choice for shaping and maintenance time, while the BD membrane is good for osteogenesis, and the BP membrane is suitable for spatial maintenance. To meet the clinical requirements of guided bone regeneration, using two different kinds of collagen membranes concurrently to exert their respective advantages is an option worth considering.

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration.

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

The progress of research on the application of redox nanomaterials in disease therapy.

Redox imbalance can trigger cell dysfunction and damage and plays a vital role in the origin and progression of many diseases. Maintaining the balance between oxidants and antioxidants in vivo is a complicated and arduous task, leading to ongoing research into the construction of redox nanomaterials. Nanodrug platforms with redox characteristics can not only reduce the adverse effects of oxidative stress on tissues by removing excess oxidants from the body but also have multienzyme-like activity, which can play a cytotoxic role in tumor tissues through the catalytic oxidation of their substrates to produce harmful reactive oxygen species such as hydroxyl radicals. In this review, various redox nanomaterials currently used in disease therapy are discussed, emphasizing the treatment methods and their applications in tumors and other human tissues. Finally, the limitations of the current clinical application of redox nanomaterials are considered.

An insight into novel therapeutic potentials of taxifolin.

Taxifolin is a flavonoid compound, originally isolated from the bark of Douglas fir trees, which is often found in foods such as onions and olive oil, and is also used in commercial preparations, and has attracted the interest of nutritionists and medicinal chemists due to its broad range of health-promoting effects. It is a powerful antioxidant with excellent antioxidant, anti-inflammatory, anti-microbial and other pharmacological activities. This review focuses on the breakthroughs in taxifolin for the treatment of diseases from 2019 to 2022 according to various systems of the human body, such as the nervous system, immune system, and digestive system, and on the basis of this review, we summarize the problems of current research and try to suggest solutions and future research directions.

Overview of strategies to improve the antibacterial property of dental implants.

The increasing number of peri-implant diseases and the unsatisfactory results of conventional treatment are causing great concern to patients and medical staff. The effective removal of plaque which is one of the key causes of peri-implant disease from the surface of implants has become one of the main problems to be solved urgently in the field of peri-implant disease prevention and treatment. In recent years, with the advancement of materials science and pharmacology, a lot of research has been conducted to enhance the implant antimicrobial properties, including the addition of antimicrobial coatings on the implant surface, the adjustment of implant surface topography, and the development of new implant materials, and significant progress has been made in various aspects. Antimicrobial materials have shown promising applications in the prevention of peri-implant diseases, but meanwhile, there are some shortcomings, which leads to the lack of clinical widespread use of antimicrobial materials. This paper summarizes the research on antimicrobial materials applied to implants in recent years and presents an outlook on the future development.

Research Progress of Photothermal Nanomaterials in Multimodal Tumor Therapy.

The aggressive growth of cancer cells brings extreme challenges to cancer therapy while triggering the exploration of the application of multimodal therapy methods. Multimodal tumor therapy based on photothermal nanomaterials is a new technology to realize tumor cell thermal ablation through near-infrared light irradiation with a specific wavelength, which has the advantages of high efficiency, less adverse reactions, and effective inhibition of tumor metastasis compared with traditional treatment methods such as surgical resection, chemotherapy, and radiotherapy. Photothermal nanomaterials have gained increasing interest due to their potential applications, remarkable properties, and advantages for tumor therapy. In this review, recent advances and the common applications of photothermal nanomaterials in multimodal tumor therapy are summarized, with a focus on the different types of photothermal nanomaterials and their application in multimodal tumor therapy. Moreover, the challenges and future applications have also been speculated.

Compression versus no compression after endovenous radiofrequency ablation: A meta-analysis of randomized controlled trials.

OBJECTIVES: The aim of this meta-analysis was to compare compression with no-compression, after radiofrequency endothermal ablation of a truncal varicose vein. METHODS: Databases, such as PubMed, Embase, Cochran Library, and Web of Science, were independently searched by two researchers for relevant literature, preliminary screening was performed, and the full text was read to select studies that met the inclusion criteria. The quality of the included literature was evaluated using the Cochrane Risk of Bias tool, and meta-analysis was performed using Review Manager 5.4. RESULTS: A total of four randomized controlled trials were included and a total of 552 patients were involved. Among them, 273 patients were in the compression group and 279 in the no-compression group. Meta-analysis results showed that the pain using the 100 mm Visual Analogue Scale was lower in the compression group than the pain in the no-compression group (MD = -4.22, 95% CI = -7.95 - -0.49, p = 0.03). No significant differences in terms of occlusion rate (RR = 0.99, 95% CI = 0.96-1.02, p = 0.55), Aberdeen Varicose Vein Questionnaire (MD = 0.46, 95% CI = -0.80-1.73, p = 0.47), and complications (OR = 1.33, 95% CI = 0.61-2.94, p = 0.47) were observed between groups. CONCLUSIONS: This meta-analysis suggests that compression therapy reduced post-operative pain compared to the no-compression group. However, no additional advantages were observed in terms of occlusion rates, quality of life scores and complications.

Clinical efficacy of transjugular intrahepatic portosystemic shunt created through left or right branches of the portal vein: A meta-analysis.

Background and aim: Transjugular intrahepatic portosystemic shunt (TIPS) is a technique successfully used to treat portal hypertension and its complications. However, the choice of the branch, left (L) or right (R), of the portal vein resulting in a better outcome is still under debate. Therefore, this meta-analysis aims to evaluate which branch has a better curative effect on patients treated with TIPS. Methods: PubMed, EMBASE, Web of science, Cochrane Library databases, Wanfang database and CBM were used for our search in October 2019 and updated in June 2021. The following parameters were used in evaluation: overall mortality, hepatic encephalopathy, shunt dysfunction, variceal rebleeding and rate of postoperative ascites. Results: There were seven studies included. The sample size was 1940. A lower risk of mortality was observed in TIPS-L-treated patients compared with TIPS-R-treated ones (OR â€‹= â€‹0.65, 95% CI â€‹= â€‹0.50-0.85, p â€‹= â€‹0.002). A lower risk of shunt dysfunction was observed in TIPS-L-treated patients compared with TIPS-R-treated ones (OR â€‹= â€‹0.53, 95% CI â€‹= â€‹0.33-0.87, p â€‹= â€‹0.01). And the TIPS-L group had a significantly higher hepatic encephalopathy-free rate than the TIPS-R group (OR â€‹= â€‹0.59, 95% CI â€‹= â€‹0.44-0.78, p â€‹= â€‹0.0002). However, the rate of rebleeding (OR â€‹= â€‹0.75, 95% CI â€‹= â€‹0.55-1.03, p â€‹= â€‹0.07) and incidence of postoperative ascites (OR â€‹= â€‹1.14, 95% CI â€‹= â€‹0.86-1.51, p â€‹= â€‹0.38) was not statistically significant between the two groups. Conclusions: Based on the currently available evidence, the technique of TIPS through the left branch of the portal vein can significantly reduce the occurrence of overall postoperative mortality, hepatic encephalopathy and shunt dysfunction.