col2a1  (Proteintech)

Journal: International Journal of Molecular Sciences

Article Title: Betaine Downregulates RARRES1 to Alleviate Cartilage Fibrosis and Promote Hyaline Cartilage Repair

doi: 10.3390/ijms27156684

Figure Lengend Snippet: The correlation between Retinoic Acid Receptor Responder Protein 1 (RARRES1) and cartilage degeneration has been validated in clinical samples. ( A ) Scanning electron microscopy (SEM) of clinical specimens and RARRES1 immunofluorescence staining (SEM, n = 1; IF, n = 5, scale bar = 100 μm), collagen fibers were orderly arranged in the non-injured area, whereas disorganized collagen arrangement was observed in the injured area; ( B ) Comparative analysis of relative fluorescence intensity of RARRES1, *** p < 0.001; ( C ) Gene ontology (GO) pathways enriched in the RARRES1 low-expressing subset; ( D ) GO pathways enriched in the RARRES1 high-expressing subset; ( E ) Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched in the RARRES1 low-expressing subset; ( F ) KEGG pathways enriched in the RARRES1 high-expressing subset.

Article Snippet: Sections were incubated overnight at 4 °C with primary antibodies against RARRES1 (27491-1-AP, Proteintech, Wuhan, China), COL1A1 (A27820, ABclonal, Wuhan, China), and COL2A1 (A1560, ABclonal, Wuhan, China).

Techniques: Electron Microscopy, Immunofluorescence, Staining, Fluorescence, Expressing

Journal: International Journal of Molecular Sciences

Article Title: Betaine Downregulates RARRES1 to Alleviate Cartilage Fibrosis and Promote Hyaline Cartilage Repair

doi: 10.3390/ijms27156684

Figure Lengend Snippet: Single-cell virtual knockout predicts that RARRES1 promotes the upregulation of Regulator of G Protein Signaling 2 (RGS2). ( A ) Uniform Manifold Approximation and Projection (UMAP) plots showing the expression of RARRES1, Collagen Type II Alpha 1 Chain (COL2A1), Collagen Type I Alpha 1 Chain (COL1A1), SRY-box Transcription Factor 9 (SOX9), and Aggrecan (ACAN) in Osteoarthritis (OA) cartilage subpopulations; ( B ) Bubble plots depicting the expression of RARRES1, COL2A1, COL1A1, SOX9, and ACAN across different subpopulations; ( C ) Gene perturbation results following the virtual knock-out of RARRES1; ( D ) Expression level of RGS2 in the differentiation trajectory of the Regulatory Chondrocyte (RegC) subpopulation; ( E ) Differentiation trajectory of RGS2 in RegC; ( F ) RGS2 expression dynamics along the differentiation trajectory of the RegC subpopulation.

Article Snippet: Sections were incubated overnight at 4 °C with primary antibodies against RARRES1 (27491-1-AP, Proteintech, Wuhan, China), COL1A1 (A27820, ABclonal, Wuhan, China), and COL2A1 (A1560, ABclonal, Wuhan, China).

Techniques: Single Cell, Knock-Out, Expressing

Journal: International Journal of Molecular Sciences

Article Title: Betaine Downregulates RARRES1 to Alleviate Cartilage Fibrosis and Promote Hyaline Cartilage Repair

doi: 10.3390/ijms27156684

Figure Lengend Snippet: Betaine reverses the upregulation of Rarres1 and promotes Rgs2 expression in chondrocyte fibrosis. ( A ) Western blot analysis of Fibronectin 1 (Fn1), Col2a1, Sox9, and Rarres1 in the chondrocyte fibrosis model following betaine treatment; ( B – E ) Quantitative analysis of Fn1, Col2a1, Sox9, and Rarres1 expression in vitro ( n = 3); ( F ) Staining of Rarres1 and Rgs2 in the chondrocyte fibrosis model ( n = 6, scale bar = 50 μm); ( G , H ) Comparative analysis of relative fluorescence intensity of Rarres1 and Rgs2. ns: not significant, * p < 0.05, ** p < 0.01, and *** p < 0.001.

Article Snippet: Sections were incubated overnight at 4 °C with primary antibodies against RARRES1 (27491-1-AP, Proteintech, Wuhan, China), COL1A1 (A27820, ABclonal, Wuhan, China), and COL2A1 (A1560, ABclonal, Wuhan, China).

Techniques: Expressing, Western Blot, In Vitro, Staining, Fluorescence

Journal: International Journal of Molecular Sciences

Article Title: Betaine Downregulates RARRES1 to Alleviate Cartilage Fibrosis and Promote Hyaline Cartilage Repair

doi: 10.3390/ijms27156684

Figure Lengend Snippet: Betaine inhibits Rarres1 and promotes hyaline cartilage repair in vivo. ( A ) Evaluation of Cartilage Repair Using SEM ( n = 1), Safranin O (SO) ( n = 5, scale bar = 100 μm) and Masson’s Staining ( n = 5 scale bar = 100 μm); ( B ) Immunofluorescence staining of Col2a1, Col1a1, and Rarres1 in each group ( n = 5, scale bar = 100 μm/scale bar = 50 μm); ( C ) International Cartilage Repair Society (ICRS) scores in each group; ( D ) Comparative analysis of relative fluorescence intensity of Rarres1. ( E ) Comparative analysis of relative fluorescence intensity between Col2a1 and Col1a1. ns: not significant, * p < 0.05 and ** p < 0.01.

Article Snippet: Sections were incubated overnight at 4 °C with primary antibodies against RARRES1 (27491-1-AP, Proteintech, Wuhan, China), COL1A1 (A27820, ABclonal, Wuhan, China), and COL2A1 (A1560, ABclonal, Wuhan, China).

Techniques: In Vivo, Staining, Immunofluorescence, Fluorescence

Journal: International Journal of Molecular Sciences

Article Title: Betaine Downregulates RARRES1 to Alleviate Cartilage Fibrosis and Promote Hyaline Cartilage Repair

doi: 10.3390/ijms27156684

Figure Lengend Snippet: Betaine downregulates RARRES1 to promote hyaline cartilage repair. (Created in BioRender. Wang, S. (2026) https://BioRender.com/0olq826 ) (accessed on 1 May 2026). Betaine suppresses RARRES1, thereby upregulating RGS2 to enhance ROS clearance and increase the COL2A1/COL1A1 ratio, shifting repair from fibrocartilage toward hyaline cartilage. Created in BioRender style.

Article Snippet: Sections were incubated overnight at 4 °C with primary antibodies against RARRES1 (27491-1-AP, Proteintech, Wuhan, China), COL1A1 (A27820, ABclonal, Wuhan, China), and COL2A1 (A1560, ABclonal, Wuhan, China).

Techniques:

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: Regulation of extracellular matrix metabolism by AdHy@Pae in LPS-induced chondrocytes. (A) Representative immunofluorescence images showing the expression of COL2A1, SOX9, MMP9, and ADAMTS5 in different treatment groups and corresponding (B) quantitative analysis. Data are shown as mean ± SD (n = 3, ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001).

Article Snippet: Rat chondrocytes (P1) were seeded in 24-well plates (5 × 10 4 cells per well) and cultured to ∼70–80% confluence, stimulated with LPS (10 μg mL −1 , 12 h) to induce an inflammatory phenotype, and then treated with hydrogel extracts (Hy, AdHy, AdHy@Pae) for 24 h. Cells were washed three times with PBS, fixed in 4% paraformaldehyde for 15 min, permeabilized with 0.1% Triton X-100 (Aladdin, T434386) for 10 min, and blocked with 5% BSA (Solarbio, SW3015) at room temperature for 1 h. Primary antibodies were applied overnight at 4 °C: COL2A1 (Proteintech, 28459-1-AP, 1:200), SOX9 (HUABIO, HA723548, 1:1000), MMP9 (HUABIO, ET1704-69, 1:200), and ADAMTS5 (HUABIO, HA722011, 1:100).

Techniques: Immunofluorescence, Expressing

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: Expression analysis of cartilage-related proteins after treatment with AdHy@Pae. (A) Representative Western blot images showing ECM synthesis–related proteins (COL2A1, ACAN, COMP, and SOX9) and antioxidant markers (NRF2 and HO-1) in different groups. (B) Quantitative analysis of matrix-degrading enzymes (MMP13, ADAMTS5, ADAMTS1) and apoptosis-related proteins (BCL-2, Bax, and Caspase-3). Data are presented as mean ± SD (n = 3; ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001).

Article Snippet: Rat chondrocytes (P1) were seeded in 24-well plates (5 × 10 4 cells per well) and cultured to ∼70–80% confluence, stimulated with LPS (10 μg mL −1 , 12 h) to induce an inflammatory phenotype, and then treated with hydrogel extracts (Hy, AdHy, AdHy@Pae) for 24 h. Cells were washed three times with PBS, fixed in 4% paraformaldehyde for 15 min, permeabilized with 0.1% Triton X-100 (Aladdin, T434386) for 10 min, and blocked with 5% BSA (Solarbio, SW3015) at room temperature for 1 h. Primary antibodies were applied overnight at 4 °C: COL2A1 (Proteintech, 28459-1-AP, 1:200), SOX9 (HUABIO, HA723548, 1:1000), MMP9 (HUABIO, ET1704-69, 1:200), and ADAMTS5 (HUABIO, HA722011, 1:100).

Techniques: Expressing, Western Blot

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: In vivo validation of the chondroprotective and mitochondrial regulatory effects of AdHy@Pae after therapy for 4 weeks. (A) Representative immunohistochemical staining of cartilage sections for COL2A1, SOX9, MMP3, and ADAMTS1 in different groups (Sham, PBS, Hy, AdHy, and AdHy@Pae). (B) Quantitative analysis of the immunohistochemical staining intensity showing relative expression levels of anabolic (COL2A1, SOX9) and catabolic (MMP3, ADAMTS1) markers. (C) TEM images of chondrocytes showing mitochondrial ultrastructure in each group, with high-magnification views (bottom panels) indicating cristae integrity and membrane morphology. Data are presented as mean ± SD (n = 3); ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗P < 0.0001.

Article Snippet: Rat chondrocytes (P1) were seeded in 24-well plates (5 × 10 4 cells per well) and cultured to ∼70–80% confluence, stimulated with LPS (10 μg mL −1 , 12 h) to induce an inflammatory phenotype, and then treated with hydrogel extracts (Hy, AdHy, AdHy@Pae) for 24 h. Cells were washed three times with PBS, fixed in 4% paraformaldehyde for 15 min, permeabilized with 0.1% Triton X-100 (Aladdin, T434386) for 10 min, and blocked with 5% BSA (Solarbio, SW3015) at room temperature for 1 h. Primary antibodies were applied overnight at 4 °C: COL2A1 (Proteintech, 28459-1-AP, 1:200), SOX9 (HUABIO, HA723548, 1:1000), MMP9 (HUABIO, ET1704-69, 1:200), and ADAMTS5 (HUABIO, HA722011, 1:100).

Techniques: In Vivo, Biomarker Discovery, Immunohistochemical staining, Staining, Expressing, Membrane

Journal: Journal of Orthopaedic Translation

Article Title: Dermal fibroblasts attenuate osteoarthritis by restoring synovial fibroblast homeostasis

doi: 10.1016/j.jot.2026.101138

Figure Lengend Snippet: Intra-articular injection of DFbs preserved articular cartilage structure and homeostasis. A) H&E staining and SO/FG staining of articular cartilage. B) Representative micro-CT 3D images and coronal images of knee joints of rats at 8 weeks after ACLT. C) Grading of osteoarthritic cartilage damage (OARSI Criteria). D) Immunofluorescence staining of MMP3, MMP13, iNOS and COL2A1. E) Quantification of positive cells and positive area in the cartilage. n = 6. Data were presented as mean ± SD. Results were analyzed by one-way ANOVA.

Article Snippet: After antigen retrieval via citric acid, three primary antibodies were used, including COL2A1 (Servicebio, China), Vimentin (Servicebio, China) and eGFP (ProteinTech, China).

Techniques: Injection, Staining, Micro-CT, Immunofluorescence

Journal: Journal of Orthopaedic Translation

Article Title: Dermal fibroblasts attenuate osteoarthritis by restoring synovial fibroblast homeostasis

doi: 10.1016/j.jot.2026.101138

Figure Lengend Snippet: DFbs improve the inflammatory phenotype of synovial fibroblasts and chondrocytes via paracrine secretion. A) Schematic of the transwell co-culture system for synovial fibroblasts/chondrocytes and DFbs. B) Volcano plot of DEGs in the FI group and DFI group. C) GO enrichment analysis of DEGs between the FI group and DFI group. D) GSEA highlighting the enrichment of gene sets associated with inflammatory response. E) Expression profiles of inflammation-related genes and cell adhesion-related genes in the three cell groups. F) IL-6 immunofluorescence staining of synovial fibroblasts in the normal culture, IL-1β-stimulated, and IL-1β + DFb co-culture groups. Scale bar: 50 μm (Row 1); 25 μm (Row 2). G) Quantification of IL-6+ cells. n = 3. Data were presented as mean ± SD. Results were analyzed by one-way ANOVA. H) Axial fluorescence intensity of IL-6 in representative synovial fibroblasts. I) Volcano plot of DEGs between the CI group and DCI group. J) Intersection of downregulated genes in IL1β-stimulated chondrocytes and upregulated genes in IL1β-stimulated chondrocytes co-cultured with DFbs (vs. IL1β-stimulated chondrocytes alone) and intersection of upregulated genes in IL1β-stimulated chondrocytes and downregulated genes in IL1β-stimulated chondrocytes co-cultured with DFbs (vs. IL1β-stimulated chondrocytes alone). K) GO enrichment analysis of genes derived from the aforementioned intersection. L) Clustered heatmap of genes related to inflammation and ECM. M) RT-qPCR analysis of Mmp9 , Mmp13 , Acan , and Col2a1 . n = 6. Data were presented as mean ± SD. Results were analyzed by one-way ANOVA. N) Alcian blue staining of chondrocytes in three groups (Control, IL-1β-stimulated group, IL-1β-stimulated + DFb co-culture group). Scale bar: 2 mm.

Article Snippet: After antigen retrieval via citric acid, three primary antibodies were used, including COL2A1 (Servicebio, China), Vimentin (Servicebio, China) and eGFP (ProteinTech, China).

Techniques: Co-Culture Assay, Expressing, Immunofluorescence, Staining, Fluorescence, Cell Culture, Derivative Assay, Quantitative RT-PCR, Control

Journal: Journal of Orthopaedic Translation

Article Title: Dermal fibroblasts attenuate osteoarthritis by restoring synovial fibroblast homeostasis

doi: 10.1016/j.jot.2026.101138

Figure Lengend Snippet: Paracrine APOD from DFbs inhibited inflammatory activation of FLS and catabolic phenotype of chondrocytes. A) Workflow diagram of proteomic sequencing of fibroblast supernatants. B) Intersection of proteins detected in DFb supernatant, human secreted proteins, and human secreted immunoglobulins. C) GO enrichment analysis of secreted proteins from DFbs. D) Intersection of DFb secreted proteins, downregulated DEGs in OA SL Fb, and downregulated DEGs in in vitro cultured OA FLS. E) Cluster heatmap of expression profiles of genes from the aforementioned intersection in DFbs, healthy synovial fibroblasts (HF), and OA FLS. F) Fold change in APOD mRNA expression between healthy SL Fb and OA SL Fb (with healthy SL Fb as the reference). G) Fold change in APOD mRNA expression between healthy synovial fibroblasts (HF), DFb and OA FLS (with healthy synovial fibroblasts as the reference). H, J) RT-qPCR analysis of pro-inflammatory genes ( Nos2 , Il6 , Ptgs2 ) in FLS (H), and matrix metabolic genes ( Mmp9 , Mmp13 , Col2a1 ) in chondrocytes (J), after co-culture with control, empty vector-transfected, APOD-overexpressing (APOD-OE) DFbs, or treatment with recombinant APOD protein. I, K) RT-qPCR analysis of the above gene panels in FLS (I) and chondrocytes (K), after co-culture with control, negative control siRNA-transfected, or APOD-knockdown (APOD-si) DFb. n = 6. Data were presented as mean ± SD. Results were analyzed by one-way ANOVA. ∗∗P < 0.01. L) Representative Western blots of iNOS and IL-6 in FLS from the indicated groups, with β-actin (ACTB) as the loading control. M) Representative Western blots of MMP9 in chondrocytes from the indicated groups, with ACTB as the loading control.

Article Snippet: After antigen retrieval via citric acid, three primary antibodies were used, including COL2A1 (Servicebio, China), Vimentin (Servicebio, China) and eGFP (ProteinTech, China).

Techniques: Activation Assay, Sequencing, In Vitro, Cell Culture, Expressing, Quantitative RT-PCR, Co-Culture Assay, Control, Plasmid Preparation, Transfection, Recombinant, Negative Control, Knockdown, Western Blot

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: Regulation of extracellular matrix metabolism by AdHy@Pae in LPS-induced chondrocytes. (A) Representative immunofluorescence images showing the expression of COL2A1, SOX9, MMP9, and ADAMTS5 in different treatment groups and corresponding (B) quantitative analysis. Data are shown as mean ± SD (n = 3, ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001).

Article Snippet: For immunohistochemistry, primary antibodies were COL2A1 (HUABIO, HA722733, 1:1000), SOX9 (Proteintech, 68350-1-Ig, 1:500), MMP3 (Servicebio, GB11132, 1:500), and ADAMTS1 (Affinity, DF13268, 1:100); sections were incubated with HRP-conjugated polymer secondary antibodies (Affinity, S0001), developed with DAB (Servicebio, G1212), and counterstained with hematoxylin.

Techniques: Immunofluorescence, Expressing

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: Expression analysis of cartilage-related proteins after treatment with AdHy@Pae. (A) Representative Western blot images showing ECM synthesis–related proteins (COL2A1, ACAN, COMP, and SOX9) and antioxidant markers (NRF2 and HO-1) in different groups. (B) Quantitative analysis of matrix-degrading enzymes (MMP13, ADAMTS5, ADAMTS1) and apoptosis-related proteins (BCL-2, Bax, and Caspase-3). Data are presented as mean ± SD (n = 3; ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001).

Article Snippet: For immunohistochemistry, primary antibodies were COL2A1 (HUABIO, HA722733, 1:1000), SOX9 (Proteintech, 68350-1-Ig, 1:500), MMP3 (Servicebio, GB11132, 1:500), and ADAMTS1 (Affinity, DF13268, 1:100); sections were incubated with HRP-conjugated polymer secondary antibodies (Affinity, S0001), developed with DAB (Servicebio, G1212), and counterstained with hematoxylin.

Techniques: Expressing, Western Blot

Journal: Bioactive Materials

Article Title: A dual-functional hydrogel integrating adhesive and lubricating interfaces for mitochondrial protection–Driven cartilage regeneration

doi: 10.1016/j.bioactmat.2026.02.051

Figure Lengend Snippet: In vivo validation of the chondroprotective and mitochondrial regulatory effects of AdHy@Pae after therapy for 4 weeks. (A) Representative immunohistochemical staining of cartilage sections for COL2A1, SOX9, MMP3, and ADAMTS1 in different groups (Sham, PBS, Hy, AdHy, and AdHy@Pae). (B) Quantitative analysis of the immunohistochemical staining intensity showing relative expression levels of anabolic (COL2A1, SOX9) and catabolic (MMP3, ADAMTS1) markers. (C) TEM images of chondrocytes showing mitochondrial ultrastructure in each group, with high-magnification views (bottom panels) indicating cristae integrity and membrane morphology. Data are presented as mean ± SD (n = 3); ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗P < 0.0001.

Article Snippet: For immunohistochemistry, primary antibodies were COL2A1 (HUABIO, HA722733, 1:1000), SOX9 (Proteintech, 68350-1-Ig, 1:500), MMP3 (Servicebio, GB11132, 1:500), and ADAMTS1 (Affinity, DF13268, 1:100); sections were incubated with HRP-conjugated polymer secondary antibodies (Affinity, S0001), developed with DAB (Servicebio, G1212), and counterstained with hematoxylin.

Techniques: In Vivo, Biomarker Discovery, Immunohistochemical staining, Staining, Expressing, Membrane