3D Bioprinted Xanthan Hydrogels with Dual Antioxidant and Chondrogenic Functions for Post-traumatic Cartilage Regeneration.

Intra-articular trauma typically initiates the overgeneration of reactive oxidative species (ROS), leading to post-traumatic osteoarthritis and cartilage degeneration. Xanthan gum (XG), a branched polysaccharide, has shown its potential in many biomedical fields, but some of its inherent properties, including undesirable viscosity and poor mechanical stability, limit its application in 3D printed scaffolds for cartilage regeneration. In this project, we developed 3D bioprinted XG hydrogels by modifying XG with methacrylic (MA) groups for post-traumatic cartilage therapy. Our results demonstrated that the chemical modification optimized the viscoelasticity of the bioink, improved printability, and enhanced the mechanical properties of the resulting scaffolds. The XG hydrogels also exhibit decent ROS scavenging capacities to protect stem cells from oxidative stress. Furthermore, XGMA(H) (5% MA substitution) exhibited superior chondrogenic potential in vitro and promoted cartilage regeneration in vivo. These dual-functional XGMA hydrogels may provide a new opportunity for cartilage tissue engineering.

P2 purinergic receptors regulate the progression of colorectal cancer.

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

An injectable collagen-genipin-carbon dot hydrogel combined with photodynamic therapy to enhance chondrogenesis.

Collagen has been widely used for cartilage repair, but its low stiffness and rapid degradation disfavor chondrogenesis. Here we conjugated biocompatible carbon dot nanoparticles (CD NPs) onto collagen through a natural product crosslinker (genipin) to prepare an injectable hydrogel (termed collagen-genipin-CD nanoparticles, CGN). The CGN hydrogel showed increased stiffness due to the cross-linking effect of genipin and the presence of CD NPs, and could produce a moderate amount of reactive oxygen species (ROS) by photodynamic therapy (PDT). Both the stiffness enhancement and ROS generation resulted in improved chondrogenic differentiation of bone marrow-derived stem cells (BMSCs) and the subsequent enhanced cartilage regeneration for cartilage defect repair. Specifically, the CGN hydrogel presented a 21-fold higher compression modulus and a 39.3% lower degradation rate than the pure collagen hydrogel. A combination of both PDT and CGN hydrogel increased the BMSCs proliferation by 50.3%, upregulated their expression of cartilage-specific genes by multiple folds, and enhanced GAG secretion by 205.1% on day 21. This combination also accelerated the cartilage regeneration within as short as 8 weeks. The stiffness enhancement and ROS generation synergistically contributed to chondrogenic differentiation by regulating the TGF-ß/SMAD and mTOR signaling pathway, respectively. The combination of CD-modified hydrogel injection and PDT treatment represents a new strategy for minimally invasive repair of cartilage defects.

Comparison of rheumatoid arthritis (RA) and osteoarthritis (OA) based on microarray profiles of human joint fibroblast-like synoviocytes.

The purpose of the present study was to investigate the underlying molecular mechanism of osteoarthritis (OA) and rheumatoid arthritis (RA) based on microarray profiles. Three human joint fibroblast-like synoviocytes (FLSs) microarray profiles including 26 OA samples, 33 RA samples, and 20 healthy control (HC) samples were downloaded from the GEO database. Differentially expressed genes (DEGs) between OA and HC (DEGsOA) and RA and HC (DEGsRA) were identified. Co-expressed and specific genes were analysed between DEGsOA and DEGsRA. Gene ontology, KEGG pathway enrichment, PPI network, and GSEA were performed to predict the function of DEGs. Two hundred seventy-six and 410 differential genes in DEGsOA and DEGsRA were observed. One hundred fifty coexpressed genes and 126 OA-specific genes (SELE, SERPINE1, and NFKBIA were the key genes) between DEGsOA and DEGsRA were enriched in the tumour necrosis factor (TNF) signalling pathway. However, 260 RA-specific genes of which the key genes were CCR5, CCR7, CXCR4, CCL5, and CCR4 were enriched in chemokine signalling pathway. Therefore, FLSs might exert an inflammatory effect by regulating TNF signalling pathway, targeting SELE, SERPINE1, and NFKBIA during the process of OA. Although TNF signalling pathway was also involved in the synovitis of RA, chemokine signalling pathway played the key role in RA FLSs mediating cell migration, invasion, and release of chemotaxis. In addition, CCR5, CCR7, CXCR4, CCL5, and CCR4 might be hub genes in RA. The different biomarkers and pathways identified in OA and RA may provide references for further study. SIGNIFICANCE OF THE STUDY: This study revealed the similar and different mechanisms of FLSs and different biomarkers that might with important regulatory effects on RA and OA. In OA, FLSs played an inflammatory role through TNF signalling pathway, targeting SELE, SERPINE1, and NFKBIA. Although TNF signalling pathway was also involved in the synovitis of RA, chemokine signalling pathway was a crucial pathway in mediating FLSs migration, invasion, and release of chemotaxis. CCR5, CCR7, CXCR4, CCL5, and CCR4 might be keys genes in RA. We expect that our results will bring more comprehensively understanding between RA and OA for researchers.

Andrographolide prevents human nucleus pulposus cells against degeneration by inhibiting the NF-κB pathway.

Intervertebral disc degeneration (IDD) is among the most common spinal disorders, pathologically characterized by excessive cell apoptosis and production of proinflammatory factors. Pharmacological targeting of nucleus pulposus (NP) degeneration may hold promise in IDD therapy, but it is limited by adverse side effects and nonspecificity of drugs. In this study, we used a natural compound, andrographolide (ANDRO), which has been widely used to intervene inflammatory and apoptotic diseases in the investigation of NP degeneration based on IDD-patients-derived NP cells by lipopolysaccharide (LPS) treatment for the preservation of degeneration. The results showed that LPS maintained the degeneration status of NP cells as evidenced by a high apoptosis rate and the expression of degenerative and inflammatory mediators after LPS treatment. ANDRO reversed the effects of LPS-caused degeneration of NP cells and maintained the phenotype of NP cells, as demonstrated by flow cytometry, degenerative mediators (ADAMTS4 and ADAMTS5), inflammatory factors (COX2, PGE2, MMP-13, and MMP-3), biomarkers of NP cells (SOX9, ACAN, and COL2A1) expressions, and glycosaminoglycan secretion. We also found the involvement of the nuclear factor kappa-light-chain-enhancer of the activated B cells (NF-κB) pathway in ANDRO treatment, indicating that ANDRO prevented the LPS-preserved degeneration of NP cells by inhibiting the NF-κB pathway. This study may provide a reference for clinic medication of IDD therapy.

Artemisinin Ameliorates Osteoarthritis by Inhibiting the Wnt/ß-Catenin Signaling Pathway.

BACKGROUND/AIMS: Current drug therapies for osteoarthritis (OA) are not practical because of the cytotoxicity and severe side-effects associated with most of them. Artemisinin (ART), an antimalarial agent, is well known for its safety and selectivity to kill injured cells. Based on its anti-inflammatory activity and role in the inhibition of OA-associated Wnt/ß-catenin signaling pathway, which is crucial in the pathogenesis of OA, we hypothesized that ART might have an effect on OA. METHODS: The chondro-protective and antiarthritic effects of ART on interleukin-1-beta (IL-1ß)-induced and OA patient-derived chondrocytes were investigated in vitro using cell viability assay, glycosaminoglycan secretion, immunofluorescence, quantitative reverse transcription-polymerase chain reaction, and western blotting. We also used OA model rats constructed by anterior cruciate ligament transection and medial meniscus resection (ACLT+MMx) in the joints to investigate the effects of ART on OA by gross observation, morphological staining, immunohistochemistry, and enzyme-linked immunosorbent assay. RESULTS: ART exhibited potent anti-inflammatory effects by inhibiting the expression of proinflammatory chemokines and cytokines, including interleukin (IL)-1ß, IL-6, tumor necrosis factor alpha, and matrix metallopeptidase-13. It also showed favorable chondro-protective effect as evidenced by enhanced cell proliferation and viability, increased glycosaminoglycan deposition, prevention of chondrocyte apoptosis, and degeneration of cartilage. Further, ART inhibited OA progression and cartilage degradation via the Wnt/ß-catenin signaling pathway, suggesting that it might serve as a Wnt/ß-catenin antagonist to reduce inflammation and prevent cartilage degradation. CONCLUSION: In conclusion, ART alleviates IL-1ß-mediated inflammatory response and OA progression by regulating the Wnt/ß-catenin signaling pathway. Thereby, it might be developed as a potential therapeutic agent for OA.

In vitro culture expansion impairs chondrogenic differentiation and the therapeutic effect of mesenchymal stem cells by regulating the unfolded protein response.

In vitro expansion of mesenchymal stem cells (MSCs) has been implicated in loss of multipotency, leading to impaired chondrogenic potential and an eventual therapeutic effect, as reported in our previous study. However, the precise regulatory mechanism is still unclear. Here, we demonstrate that endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) were involved in transformation of MSCs induced by in vitro culture based on the comparative profiling of in vitro cultured bone marrow MSCs at passage 3 (P3 BMSCs) vs. fresh P0 BMSCs by microarray analysis. Indeed, RT-PCR and Western blot analysis showed significantly lower expression levels of three key UPR-related molecules, ATF4, ATF6 and XBP1, in P3 BMSCs than P0 BMSCs. Further, we found that UPR suppression by 4-phenylbutyrate (4-PBA) reduced the chondrogenic potential of P0 BMSCs and further cartilage regeneration. Conversely, UPR induction by tunicamycin (TM) enhanced the chondrogenic differentiation of P3 BMSCs and the therapeutic effect on cartilage repair. Thus, the decline in the chondrogenic potential of stem cells after in vitro culture and expansion may be due to changes in ER stress and the UPR pathway.

LncRNA CASC2 inhibited the viability and induced the apoptosis of hepatocellular carcinoma cells through regulating miR-24-3p.

Cancer susceptibility candidate 2 (CASC2), a recently discovered long non-coding RNA (lncRNA), was confirmed to play numerous roles in several human cancers. However, the involvement and concrete mechanism of CASC2 in hepatocellular carcinoma (HCC) still need to be further elucidated. The relative expressions of CASC2 and miR-24-3p in HCC tissue and cell lines were determined by quantitative real-time PCR (qRT-PCR). The effects of CASC2 and miR-24-3p on HCC cells were further assessed via cell viability and apoptosis. In vivo tumorigenesis assay was performed to verify the inhibition effect of CASC2 on the tumor growth and further clarify the important role of miR-24-3p in this mechanism. Compared with the paired normal tissues, the relative expression of CASC2 significantly reduced in the HCC tissues, while miR-24-3p as determined by qRT-PCR obviously increased in the HCC tissues. This observation was also found in HCC cell lines. Meanwhile, the expression of CASC2 was negatively related to miR-24-3p expression in the HCC tissues (r = -0.804, P < 0.001). CASC2 could negatively regulate the expression of miR-24-3p in vitro. Moreover, CASC2 overexpression resulted in the growth inhibitory and apoptosis-inducing effects on HCC cells, but the up-regulation of miR-24-3p greatly eliminated the CASC2-induced effects. The tumorigenesis of HCC cells was restrained significantly by CASC2 overexpression as shown by decreased tumor volume and growth rate. However, miR-24-3p up-regulation rescued the inhibition of CASC2 on the tumor growth in tumor-bearing mice. LncRNA CASC2 inhibited the viability and induced the apoptosis of HCC cells through regulating miR-24-3p.