Biophysical Electrical and Mechanical Stimulations for Promoting Chondrogenesis of Stem Cells on PEDOT:PSS Conductive Polymer Scaffolds.

The investigation of the effects of electrical and mechanical stimulations on chondrogenesis in tissue engineering scaffolds is essential for realizing successful cartilage repair and regeneration. The aim of articular cartilage tissue engineering is to enhance the function of damaged or diseased articular cartilage, which has limited regenerative capacity. Studies have shown that electrical stimulation (ES) promotes mesenchymal stem cell (MSC) chondrogenesis, while mechanical stimulation (MS) enhances the chondrogenic differentiation capacity of MSCs. Therefore, understanding the impact of these stimuli on chondrogenesis is crucial for researchers to develop more effective tissue engineering strategies for cartilage repair and regeneration. This study focuses on the preparation of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conductive polymer (CP) scaffolds using the freeze-drying method. The scaffolds were fabricated with varying concentrations (0, 1, 3, and 10 wt %) of (3-glycidyloxypropyl) trimethoxysilane (GOPS) as a crosslinker and an additive to tailor the scaffold properties. To gain a comprehensive understanding of the material characteristics and the phase aggregation phenomenon of PEDOT:PSS scaffolds, the researchers performed theoretical calculations of solubility parameters and surface energies of PSS, PSS-GOPS, and PEDOT polymers, as well as conducted material analyses. Additionally, the study investigated the potential of promoting chondrogenic differentiation of human adipose stem cells by applying external ES or MS on a PEDOT:PSS CP scaffold. Compared to the group without stimulation, the group that underwent stimulation exhibited significantly up-regulated expression levels of chondrogenic characteristic genes, such as SOX9 and COL2A1. Moreover, the immunofluorescence staining images exhibited a more vigorous fluorescence intensity of SOX9 and COL II proteins that was consistent with the trend of the gene expression results. In the MS experiment, the strain excitation exerted on the scaffold was simulated and transformed into stress. The simulated stress response showed that the peak gradually decreased with time and approached a constant value, with the negative value of stress representing the generation of tensile stress. This stress response quantification could aid researchers in determining specific MS conditions for various materials in tissue engineering, and the applied stress conditions could be further optimized. Overall, these findings are significant contributions to future research on cartilage repair and biophysical ES/MS in tissue engineering.

Use of bisphosphonates and the risk of osteonecrosis among cancer patients: a systemic review and meta-analysis of the observational studies.

PURPOSE: This study aims to systematically review observational studies evaluating the use of bisphosphonates (BPs) and risk of osteonecrosis of the jaw (ONJ) among cancer patients. METHODS: PubMed, Embase, and Cochrane Library were screened from database inception to Aug 2012. Two reviewers independently identified cohort and case-control studies evaluating the use of oral or intravenous (IV) BPs and the risk of ONJ and extracted the characteristics of the studies and risk estimates. Pooled estimates of odds ratios and 95 % confidence intervals were derived by random effects meta-analysis. Subgroup analyses were carried out according to patients' characteristics and route of BP use. RESULTS: We identified eight studies, including 1,389 cases and 569,620 controls. Use of BPs was associated with a significantly increased risk of ONJ (odds ratio (OR) 4.25; 95 % confidence interval (CI) 3.67-5.36; I (2) = 0 %). The summary OR was 4.22 (95 % CI 3.21-5.54; I (2) = 0 %) for adjusted studies. IV BPs were associated with higher risk (OR 4.27; 95 % CI 3.38-5.40; I (2) = 0 %) than oral BPs (OR 1.18; 95 % CI 0.89-1.56; I (2) = 0 %). Hospital-based studies were associated with higher risk estimates than population-based studies. CONCLUSION: The available evidence suggests that use of BPs in cancer patients is associated with a substantial risk for ONJ. Patients receiving IV BP are at the highest risk. It is important to assess oral health before initiating therapy and to avoid dental procedures during the active phase of intravenous BP therapy.

Injectable, Antioxidative, and Tissue-Adhesive Nanocomposite Hydrogel as a Potential Treatment for Inner Retina Injuries.

Reactive oxygen species (ROS) have been recognized as prevalent contributors to the development of inner retinal injuries including optic neuropathies such as glaucoma, non-arteritic anterior ischemic optic neuropathy, traumatic optic neuropathy, and Leber hereditary optic neuropathy, among others. This underscores the pivotal significance of oxidative stress in the damage inflicted upon retinal tissue. To combat ROS-related challenges, this study focuses on creating an injectable and tissue-adhesive hydrogel with tailored antioxidant properties for retinal applications. GelCA, a gelatin-modified hydrogel with photo-crosslinkable and injectable properties, is developed. To enhance its antioxidant capabilities, curcumin-loaded polydopamine nanoparticles (Cur@PDA NPs) are incorporated into the GelCA matrix, resulting in a multifunctional nanocomposite hydrogel referred to as Cur@PDA@GelCA. This hydrogel exhibits excellent biocompatibility in both in vitro and in vivo assessments, along with enhanced tissue adhesion facilitated by NPs in an in vivo model. Importantly, Cur@PDA@GelCA demonstrates the potential to mitigate oxidative stress when administered via intravitreal injection in retinal injury models such as the optic nerve crush model. These findings underscore its promise in advancing retinal tissue engineering and providing an innovative strategy for acute neuroprotection in the context of inner retinal injuries.