Principles and Applications of Safranin O-Fast Green Staining in Cartilage Histological Evaluation
Principles and Applications of Safranin O-Fast Green Staining in Cartilage Histological Evaluation
Safranin O-Fast Green staining is a classic staining method commonly used in cartilage histological evaluation. It is mainly applied to show the retention, loss, and distribution changes of proteoglycans and glycosaminoglycans in the cartilage matrix. This method uses the cationic staining of acidic matrix components by Safranin O and the counterstaining of collagen, cytoplasm, and background tissues by Fast Green, making cartilage matrix degeneration, surface abrasion, fissure formation, and subchondral bone changes more visually distinguishable.
Keywords: Safranin O; Fast Green; cartilage histology; proteoglycan; glycosaminoglycan; chondroitin sulfate; osteoarthritis; OARSI score; Mankin score
1 Basic Objectives of Cartilage Histological Evaluation
1.1 Cartilage Matrix Integrity
(1) Extracellular matrix retention
Articular cartilage is composed of a small number of chondrocytes and a large amount of extracellular matrix. The type II collagen network determines the tensile strength of cartilage, while proteoglycans and glycosaminoglycans determine water retention, compressive resistance, and elastic cushioning properties. Early cartilage degeneration is often characterized by proteoglycan loss, while obvious collagen network disruption, cartilage fissures, and reduced cartilage thickness usually occur in more advanced degeneration.
(2) Proteoglycan visualization
The core value of Safranin O-Fast Green staining lies in displaying the distribution of acidic proteoglycans in the cartilage matrix. Normal cartilage matrix is usually orange-red to red. When degeneration, enzymatic digestion, or mechanical injury occurs, Safranin O staining intensity weakens, and severe areas may show local or extensive loss of staining.
(3) Observation of zonal changes
Different cartilage zones differ in proteoglycan content, cell morphology, and collagen arrangement. Safranin O staining can help observe matrix changes in the superficial zone, middle zone, deep zone, and calcified cartilage zone, making it especially suitable for determining whether degeneration has extended from the superficial zone to deeper layers.
1.2 Degree of Cartilage Degeneration
In osteoarthritis, traumatic cartilage injury, cartilage defect repair, drug intervention, and tissue-engineered cartilage evaluation, simply observing cartilage thickness is insufficient to reflect matrix quality. Safranin O-Fast Green staining can simultaneously display cartilage surface integrity, matrix staining intensity, cell arrangement, fissure depth, and subchondral bone structure, making it an important basis for histological scoring.
1.3 Quality of Repair Tissue
In cartilage repair experiments, repair tissue may appear as hyaline cartilage, fibrocartilage, or mixed tissue. Hyaline cartilage-like tissue usually shows strong Safranin O-positive staining and good integration with surrounding normal cartilage. Fibrocartilage often shows enhanced Fast Green staining and weaker Safranin O staining, indicating more collagenous fibrous tissue and insufficient proteoglycan deposition.
2 Staining Principles of Safranin O-Fast Green
2.1 Recognition of Acidic Matrix by Safranin O
(1) Characteristics of a cationic dye
Safranin O is a cationic basic dye that binds to negatively charged acidic glycosaminoglycans in the cartilage matrix. Cartilage proteoglycans contain abundant acidic groups such as chondroitin sulfate and keratan sulfate, so they can be clearly stained red or orange-red by Safranin O.
(2) Indicator of proteoglycan content
Safranin O staining intensity is usually correlated with the content of proteoglycans and glycosaminoglycans in the cartilage matrix. Stronger staining generally indicates better retention of acidic proteoglycans, while weaker staining often suggests matrix degeneration, proteoglycan loss, or insufficient quality of repair tissue.
(3) Display of spatial distribution
Proteoglycan content is not completely uniform among different zones of normal articular cartilage. Therefore, Safranin O staining can also display zonal differences. In degenerated tissues, the superficial cartilage zone often shows weakened staining first, which may then gradually extend into the middle and deep zones.
2.2 Background Counterstaining by Fast Green
(1) Counterstaining of collagen and non-cartilaginous tissues
Fast Green is an acidic dye that stains collagen fibers, cytoplasm, and some background tissues green. In the Safranin O-Fast Green staining system, Fast Green mainly provides structural background, making cartilage, bone tissue, fibrous tissue, and cellular morphology easier to distinguish.
(2) Red-green contrast
Safranin O displays proteoglycan-rich cartilage matrix, while Fast Green displays collagenous tissues and background structures. The red-green contrast helps determine whether cartilage matrix is retained, whether repair tissue tends toward fibrosis, and the structure of subchondral bone and surrounding connective tissues.
(3) Control of differentiation
Excessive Fast Green counterstaining may obscure the red Safranin O signal, especially in mildly degenerated or weakly positive samples. Therefore, Fast Green staining time and differentiation steps must be strictly controlled.
2.3 Auxiliary Hematoxylin Nuclear Staining
Safranin O-Fast Green staining usually includes a hematoxylin nuclear staining step to display chondrocyte nuclei and bone tissue cell nuclei. Nuclear staining helps observe chondrocyte number, cell clustering, abnormal arrangement, vacuole-like changes, and subchondral bone cell structure. Overstaining of nuclei may interfere with observation of the pericellular matrix, while insufficient nuclear staining is unfavorable for judging chondrocyte morphology. Therefore, nuclear staining should be coordinated with the staining intensities of Safranin O and Fast Green.
3 Staining Procedure and Key Steps
3.1 Sample Fixation
(1) Fixative selection
Cartilage tissue is usually fixed with neutral formalin or paraformaldehyde. The purpose of fixation is to preserve tissue structure, cell morphology, and matrix components, and to prevent structural collapse during decalcification, dehydration, and embedding.
(2) Fixation time
Insufficient fixation may result in poor preservation of tissue structure, fragile sections, or tissue detachment from slides. Overfixation may affect subsequent staining uniformity. The fixation time for small-animal joint samples and large-animal cartilage samples should be adjusted according to tissue volume, bone tissue proportion, and decalcification protocol.
(3) Control of matrix loss
Glycosaminoglycans in the cartilage matrix have certain water solubility and diffusion risk. During fixation and subsequent processing, excessive soaking, prolonged strong acid treatment, and vigorous mechanical manipulation should be avoided to reduce matrix component loss.
3.2 Decalcification
(1) Necessity of decalcification
Joint samples containing subchondral bone usually require decalcification before paraffin embedding and sectioning. Decalcification quality directly affects cartilage surface integrity, subchondral bone morphology, and staining results.
(2) Acid decalcification and chelating decalcification
Strong acid decalcification is fast but may damage the cartilage matrix and reduce Safranin O staining intensity. EDTA decalcification is relatively gentle and better preserves cartilage matrix and cell morphology. For cartilage degeneration scoring and quantitative analysis, EDTA decalcification is usually more suitable.
(3) Control of decalcification endpoint
Insufficient decalcification may cause section damage or obvious knife marks. Overdecalcification may cause loose tissue, weakened matrix staining, and blurred cellular structures. Stable decalcification time and endpoint criteria should be established according to sample size.
3.3 Sectioning and Slide Attachment
(1) Section thickness
Paraffin sections of 4–6 μm are commonly used in cartilage histological evaluation. Sections that are too thick may result in overly deep staining and unclear layering; sections that are too thin may weaken the cartilage matrix signal and affect judgment of Safranin O intensity.
(2) Selection of section plane
Consistent section planes are required for articular cartilage evaluation. For example, mouse knee joint sections often need to pass through relatively standardized positions of the femoral condyle, tibial plateau, and meniscus. Deviations in section plane can affect cartilage thickness, damage area, and scoring results.
(3) Prevention of section detachment
After decalcification, osteochondral tissue may still be relatively hard, and staining involves multiple washing and differentiation steps, making section detachment more likely. Adhesive slides are recommended, and sections should be adequately baked.
3.4 Staining Steps
(1) Deparaffinization and rehydration
Paraffin sections should be deparaffinized with xylene and rehydrated through graded ethanol before entering the aqueous staining system. Incomplete deparaffinization may cause uneven staining or local staining rejection.
(2) Nuclear staining
Hematoxylin is first used for nuclear staining, followed by differentiation and bluing to clearly display nuclear structures. Nuclear staining time should be optimized according to section thickness and tissue type.
(3) Fast Green counterstaining
Fast Green is used to stain collagenous background and non-cartilaginous tissues. This step should not be too long, otherwise it may affect subsequent Safranin O coloration.
(4) Acid differentiation
Some protocols use weak acid for rapid differentiation to remove excess Fast Green. Insufficient differentiation may lead to a dark background, while excessive differentiation may affect overall tissue contrast.
(5) Safranin O staining
Safranin O staining is used to display proteoglycans in the cartilage matrix. After staining, sections should be rapidly dehydrated, cleared, and mounted to avoid excessive elution of the red signal.
4 Interpretation of Staining Results
4.1 Normal Cartilage Appearance
Normal articular cartilage has a continuous surface and clear zonal structure. The cartilage matrix shows relatively uniform Safranin O staining, appearing orange-red to red. Chondrocytes show certain zonal distribution characteristics: superficial zone cells are relatively flattened, middle and deep zone cells are more rounded, and deep zone cells are located near the tidemark region. Fast Green mainly displays subchondral bone, fibrous tissue, and background structures.
4.2 Degenerated Cartilage Appearance
(1) Weakened Safranin O staining
Early degeneration commonly shows lighter Safranin O staining in the superficial or focal regions, indicating proteoglycan loss. As degeneration progresses, weakened staining may extend into deeper zones.
(2) Surface structural damage
The cartilage surface may show roughening, fissures, fibrosis, peeling, or defects. Fissure depth is an important indicator in osteoarthritis histological scoring.
(3) Chondrocyte abnormalities
Cartilage degeneration may involve cell clustering, decreased cell number, hypertrophy-like changes, or vacuole-like changes. Safranin O-Fast Green staining can assist in observing these changes. However, if cell death or hypertrophic differentiation needs to be confirmed, immunohistochemistry or molecular assays are also required.
(4) Subchondral bone changes
Thickening of the subchondral bone plate, osteophyte formation, and changes in bone marrow cavity structure often coexist with cartilage degeneration. Fast Green counterstaining helps observe these background structures.
4.3 Repair Tissue Appearance
(1) Hyaline cartilage-like repair
If the repair area shows strong Safranin O staining, chondrocyte-like round cell distribution, and good integration with surrounding cartilage, it usually indicates that the repair tissue has good cartilage matrix characteristics.
(2) Fibrocartilage-like repair
If the repair area shows obvious Fast Green staining, weak Safranin O staining, and spindle-shaped or fibrous cell arrangement, it suggests that the repair tissue is more fibrotic and has insufficient proteoglycan deposition.
(3) Mixed-type repair
Mixed-type repair tissue is common in tissue engineering or cartilage defect repair. Some areas may be Safranin O-positive, while others show enhanced Fast Green staining. In this case, type II collagen, type I collagen, Aggrecan, and other indicators should be combined to further evaluate repair quality.
5 Applications in Osteoarthritis Research
5.1 Degeneration Grading
Safranin O-Fast Green staining is a commonly used histological evaluation method in animal models of osteoarthritis. The degree of degeneration can be graded by observing cartilage surface integrity, Safranin O staining intensity, fissure depth, cartilage thickness, and subchondral bone changes.
5.2 OARSI Scoring
The OARSI scoring system is commonly used for histological evaluation of osteoarthritis and emphasizes the depth and extent of cartilage damage. Safranin O staining can show areas of proteoglycan loss, while Fast Green can show fibrosis and bone tissue background, making this staining method suitable for supporting OARSI score interpretation.
5.3 Mankin Scoring
The Mankin score usually includes structure, cells, matrix staining, and tidemark integrity. Safranin O staining intensity is an important basis for evaluating matrix proteoglycan loss. Unstable staining conditions directly affect scoring results, so samples scored in the same batch should use a unified staining workflow whenever possible.
5.4 Evaluation of Drug Intervention
In studies of anti-inflammatory, anti-degenerative, cartilage repair-promoting, or matrix degradation-inhibiting drugs, Safranin O-Fast Green staining can be used to determine whether the drug maintains cartilage proteoglycan content, reduces surface destruction, or improves subchondral bone changes. If the staining result shows enhanced Safranin O signal, biochemical GAG detection, Aggrecan immunostaining, or qPCR should be used for further verification.
6 Applications in Cartilage Repair and Tissue Engineering
6.1 Scaffold Material Evaluation
Tissue-engineered cartilage scaffolds often need to be evaluated for whether cells form a proteoglycan-rich cartilage-like matrix within the material. Enhanced Safranin O positivity indicates increased glycosaminoglycan deposition. However, if the material itself is charged or has dye adsorption capacity, material blank controls should be included.
6.2 Stem Cell Chondrogenic Induction
After chondrogenic induction of mesenchymal stem cells, Safranin O-Fast Green staining can be used to observe cartilage-like matrix formation. In cell pellets, micromass culture, or three-dimensional hydrogel systems, Safranin O-positive regions usually indicate proteoglycan deposition. If Fast Green staining is strong while Safranin O staining is weak, this may suggest a fibrotic matrix or insufficient chondrogenic induction.
6.3 Cartilage Defect Repair Models
In full-thickness cartilage defect, osteochondral defect, and microfracture repair models, this staining method can show the boundary between the repair area and native cartilage, the matrix properties of repair tissue, surface smoothness, and subchondral bone reconstruction. To evaluate repair quality, Safranin O-Fast Green staining should usually be combined with macroscopic scoring, immunohistochemistry, and mechanical testing.
7 Quantitative Analysis and Scoring Strategies
7.1 Semi-quantitative Scoring
The most common application of Safranin O-Fast Green staining is histological scoring. Before scoring, criteria should be clearly defined, including whether the cartilage surface is intact, whether fissures enter the middle or deep zone, whether Safranin O staining is weakened, whether chondrocytes are clustered, whether the tidemark is disrupted, and whether the subchondral bone is abnormal.
7.2 Image Quantification
(1) Stained area analysis
Image analysis software can be used to measure the Safranin O-positive area, the ratio of positive area to total cartilage area, or mean optical density. This method is suitable for comparing proteoglycan retention among different treatment groups.
(2) Color separation
Because Safranin O and Fast Green may overlap in color, color separation or thresholding can be used during image quantification to extract the red signal. Threshold settings should be unified and kept consistent across all images.
(3) Zonal analysis
Cartilage degeneration has zonal characteristics. Safranin O intensity can be analyzed separately in the superficial, middle, and deep zones. Zonal analysis better reflects early degeneration than overall average values.
7.3 Limitations of Quantification
Safranin O staining intensity is significantly affected by fixation, decalcification, section thickness, staining time, and dehydration speed. Therefore, it is suitable as a histological semi-quantitative or relative comparison method and should not be used alone as an absolute quantification basis for glycosaminoglycans. If accurate GAG content measurement is required, DMMB assay, biochemical quantification, or glycosaminoglycan disaccharide composition analysis should be combined.
8 Technical Influencing Factors and Quality Control
8.1 Effect of Decalcification on Staining
Decalcification is a key pretreatment step affecting cartilage Safranin O staining results. Strong acid decalcification may cause glycosaminoglycan loss and weaken Safranin O staining. EDTA decalcification is relatively gentle and more suitable for preserving cartilage matrix. Samples processed with different decalcification methods should not be directly compared for staining intensity.
8.2 Control of Staining Time
Insufficient Safranin O staining may weaken cartilage matrix signals, while overstaining may increase background. Excessive Fast Green staining may obscure weakly positive Safranin O signals. In experiments, unified staining time, reagent batch, and dehydration workflow should be used.
8.3 Rapid Dehydration
After Safranin O staining, sections usually need to pass quickly through graded ethanol for dehydration. If the sections remain in ethanol for too long, the red signal may be eluted, resulting in lighter staining. The dehydration time should be kept consistent for all sections.
8.4 Positive and Negative Controls
(1) Positive control
Normal articular cartilage or known proteoglycan-rich cartilage tissue can be selected as a positive control to confirm the effectiveness of the Safranin O staining system.
(2) Negative or weakly positive control
Degenerated cartilage, enzymatically digested cartilage, or tissue with obvious proteoglycan loss can be used as weakly positive controls to help judge staining sensitivity.
(3) Within-batch consistency
Histological scoring samples should be stained in the same batch as much as possible. If staining must be performed in separate batches, common control sections should be included to correct for batch-to-batch differences.
9 Combined Application with Other Cartilage Evaluation Methods
Safranin O-Fast Green staining can show overall proteoglycan retention but cannot distinguish specific matrix molecules. If cartilage phenotype needs to be confirmed, immunohistochemistry for type II collagen, Aggrecan, and SOX9 can be combined. If fibrosis or abnormal repair needs to be assessed, type I collagen can be detected. If hypertrophic differentiation is of interest, type X collagen and MMP13 can be detected.
9.2 Biochemical Detection
The DMMB assay can be used to detect sulfated glycosaminoglycan content and is complementary to Safranin O staining. Chondroitin sulfate standards, disaccharide standards, and chondroitinase digestion systems can further be used to analyze GAG composition, sulfation patterns, and matrix degradation. Hydroxyproline detection can reflect total collagen content, and calcium content detection can be used to assess cartilage calcification or ossification tendency.
9.3 Molecular Detection
RT-qPCR or transcriptome analysis can detect the expression of genes such as Col2a1, Acan, Sox9, Col1a1, Col10a1, Mmp13, and Adamts5. Histological staining reflects structural outcomes, while molecular detection helps explain mechanisms of matrix synthesis and degradation.
9.4 Imaging and Mechanical Testing
Micro-CT can be used to observe subchondral bone and osteophyte changes, but it has limited ability to show unmineralized cartilage. Mechanical testing can evaluate cartilage compressive resistance and elastic performance. In cartilage repair research, combining Safranin O-Fast Green staining with mechanical performance testing better reflects the quality of repair tissue.
10 Reagent and Material Selection for Cartilage Histological Evaluation
10.1 Products Related to Safranin O-Fast Green Staining, GAG Verification, and Cartilage Matrix Evaluation
Product Module | Cat. No. | Product Name | Grade / Specification | Role in the System | Applicable Scenario |
Safranin O-Fast Green staining system | Modified Safranine O-Fast Green Cartilage Staining Solution | BioReagent, Biological Stain, for microscopy, sterile | Simultaneously displays cartilage proteoglycans and background tissue structures | Histological evaluation of osteoarthritis models, cartilage repair, and chondrogenic induction | |
Safranin O staining | Cartilage Staining Solution (Safranine O) | BioReagent, Biological Stain, for microscopy | Displays proteoglycan/GAG retention in cartilage matrix | Safranin O single staining or combined staining systems | |
Safranin O dye | Sandy yellow/safety red T aqueous solution (0.5%) | BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.5% | Cartilage GAG routine staining | Cartilage GAG routine staining | |
Safranin O dye | Sandy yellow/safety red T aqueous solution (1%) | BioReagent,Suitable for microbiology,Biological Stain,for microscopy,1% | Cartilage matrix staining condition optimization | Cartilage matrix staining condition optimization | |
Safranin O dye | Sahuang/Cinnabar T aqueous solution (2%) | BioReagent,Suitable for microbiology,Biological Stain,for microscopy,2% | Strong staining system or staining condition optimization | Strong staining system or staining condition optimization | |
Safranin O dye | Safranine T | AR, Dye content ≥85% | Preparation of Safranin O/Safranin T staining solution | Self-prepared staining systems and method optimization | |
Fast Green counterstaining | Fast Green FCF | Dye content≥85 % | Counterstaining of collagen, cytoplasm, and background tissues | Background contrast in Safranin O-Fast Green staining | |
Fast Green counterstaining | Fast Green FCF | Biological Stain | Background counterstaining dye | Display of subchondral bone, fibrous tissue, and background structures | |
Fast Green counterstaining | Fast Green FCF Staining Solution (0.1%) | BioReagent,Biological Stain,for microscopy,0.1% | Low-concentration Fast Green counterstaining | Weak Safranin O signal samples and mild background counterstaining | |
Fast Green counterstaining | Fast Green FCF Staining Solution (0.5%) | BioReagent,Biological Stain,for microscopy,0.5% | Routine Fast Green counterstaining | Cartilage histological background display | |
Fast Green counterstaining | Fast Green FCF Ethanol Staining Solution (0.5%) | BioReagent,Biological Stain,for microscopy,0.5% | Fast Green counterstaining in ethanol system | Optimization of Safranin O-Fast Green staining workflow | |
Nuclear staining | Hematoxylin | for microscopy (Hist.), indicator (pH 5.0-6.0) | Displays cell nuclei | Observation of chondrocyte number, clustering, and arrangement | |
Nuclear staining | Hematoxylin | Biological Stain | Nuclear staining | Nuclear staining before Safranin O-Fast Green staining | |
Nuclear staining | Hematoxylin | High-purity, ≥99%(HPLC) | High-purity nuclear staining reagent | Standardized histological staining | |
GAG auxiliary staining | Cartilage Staining Solution (Alcian Blue, pH1.0) | BioReagent,Biological Stain,for microscopy | Displays strongly acidic sulfated GAGs | Evaluation of cartilage sulfated glycosaminoglycans | |
GAG auxiliary staining | Cartilage Staining Solution (Alcian Blue, pH2.5) | BioReagent,Biological Stain,for microscopy | Displays acidic mucopolysaccharides/GAGs | Complementary to Safranin O results for evaluating cartilage matrix retention | |
Cartilage matrix auxiliary staining | Cartilage Staining Solution (Toluidine Blue Method) | BioReagent, for microscopy, Biological Stain | Displays acidic cartilage matrix through metachromasia | Auxiliary evaluation of chondrogenic induction and cartilage GAG deposition | |
Hyaline cartilage auxiliary staining | Hyaline Cartilage Staining Solution (Unna's Alkaline Methylene Blue Method) | BioReagent,Biological Stain,for microscopy | Displays hyaline cartilage structure | Auxiliary histological evaluation of hyaline cartilage | |
Calcification/ossification auxiliary staining | Alizarin Red S Staining Solution (0.1%, pH4.2) | BioReagent,Biological Stain,for microscopy,0.1% | Displays calcium deposition | Evaluation of cartilage calcification, ossification contamination, or subchondral bone-related changes | |
Calcification/ossification auxiliary staining | Alizarin Red S Staining Solution (0.2%, pH4.2) | BioReagent,Biological Stain,for microscopy,0.2% | Displays calcium salt deposition | Evaluation of abnormal calcification or post-hypertrophic calcification in chondrogenic systems | |
Collagen fiber auxiliary staining | Victoria Blue Collagen Fiber Staining Solution | BioReagent, Biological Stain, for microscopy, sterile | Displays collagen fiber structure | Observation of fibrocartilage, collagen deposition, and fibrosis of repair tissue | |
Chondroitin sulfate/GAG standard | Chondroitin sulfate sodium salt from bovine cartilage | standard (for CPC (cetylpyridinium chloride) titration) | Representative cartilage GAG standard | GAG-related method validation | |
Chondroitin sulfate/GAG standard | Chondroitin sulfate sodium salt from shark cartilage | ≥95% | Chondroitin sulfate standard | GAG content detection and cartilage matrix analysis | |
Chondroitin sulfate/GAG standard | Chondroitin Sulfate Sodium Salt | ≥95% | Representative cartilage GAG component | Cartilage matrix standard and GAG methodological control | |
Chondroitin sulfate/GAG standard | Chondroitin sulfate sodium (from Porcine Cartilage) | ≥90% | Animal-derived chondroitin sulfate | Cartilage matrix component research | |
Chondroitin sulfate/GAG standard | Chondroitin sulfate sodium (from Chicken Cartilage) | ≥90% | Animal-derived chondroitin sulfate | GAG controls from different cartilage sources | |
Chondroitin sulfate subtype | Chondroitin 4-sulfate sodium salt | ≥95% | 4-sulfated chondroitin standard | GAG subtype analysis and cartilage matrix composition research | |
Chondroitin sulfate subtype | Chondroitin sulfate B sodium salt | ≥90%, lyophilized powder,from porcine intestinal mucosa,lyophilized powder;average MW 30-40KDa | Dermatan sulfate/CS-B-related control | GAG subtype comparison and cartilage/connective tissue matrix research | |
Chondroitin sulfate subtype | Chondroitin sulfate C sodium salt | ≥90%, mixture of isomers,From sharks | 6-sulfated chondroitin-related standard | GAG subtype analysis and cartilage matrix composition evaluation | |
Chondroitin sulfate subtype | Chondroitin sulfate sodium salt， from shark fin | Moligand™, ≥90% | Specific sulfated CS subtype | GAG structural composition analysis | |
Chondroitin sulfate subtype | Chondroitin sulfate E sodium salt,from squid cartilage | Moligand™, ≥90% | Highly sulfated CS subtype | Cartilage GAG structure and sulfation pattern research | |
Chondroitin disaccharide standard | Chondroitin disaccharide Δdi-0S sodium salt | ≥95% | Non-sulfated CS disaccharide standard | LC/HPLC analysis of GAG composition | |
Chondroitin disaccharide standard | Chondroitin disaccharide Δdi-4S sodium salt | ≥95% | 4-sulfated CS disaccharide standard | Analysis of cartilage GAG sulfation patterns | |
Chondroitin disaccharide standard | Chondroitin disaccharide δdi-6S sodium salt | ≥90% | 6-sulfated CS disaccharide standard | Analysis of cartilage matrix GAG composition | |
Chondroitin disaccharide standard | Chondroitin disaccharide Δdi-4S6S sodium salt | ≥95% | Disulfated CS disaccharide standard | Analysis of complex sulfation patterns | |
Chondroitin disaccharide standard | Chondroitin disaccharide mixture | ≥95% | CS disaccharide mixed standard | Control for chondroitinase digestion products | |
Chondroitinase digestion | Chondroitinase ABC from Proteus vulgaris | lyophilized powder, 0.3-3 units/mg solid | Digests CS/DS-type GAGs | Cartilage GAG digestion validation and disaccharide composition analysis | |
Chondroitinase digestion | Chondroitinase ABC II | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,expressed in E.coli；≥1000 U/mg enzyme powder; ≥2000 U/mg protein | High-activity CS/DS digestion enzyme | Cartilage GAG structural analysis and cartilage matrix degradation research | |
Chondroitinase digestion | Chondroitinase AC | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥95%(SDS-PAGE),≥100 U/mg enzyme powder; ≥200 U/mg protein | Specific digestion of CS-A/CS-C and other CS subtypes | CS subtype digestion and GAG structural verification | |
Chondroitinase digestion | Chondroitinase B | Bioactive,Recombinant,ActiBioPure™,High Performance,EnzymoPure™,≥95%(SDS-PAGE),≥100 U/mg enzyme powder; ≥200 U/mg protein | Digests dermatan sulfate/CS-B-related structures | Differentiation of CS-B/DS components | |
Cartilage matrix marker | Human Aggrecan (AGC) ELISA Kit | BioReagent | Detects Aggrecan level | Evaluation of cartilage matrix synthesis and retention | |
Cartilage matrix marker | Mouse Aggrecan (AGC) ELISA Kit | BioReagent | Detects mouse Aggrecan level | Mouse osteoarthritis models and cartilage repair research | |
Cartilage matrix marker | Human Cartilage Oligomeric Matrix Protein (COMP) ELISA Kit | BioReagent | Detects COMP level | Auxiliary evaluation of cartilage matrix metabolism and cartilage injury | |
Cartilage matrix marker | Human COMP ELISA Kit | BioReagent | Detects human COMP level | Cartilage degeneration and joint pathology research | |
Cartilage matrix marker | Human Cartilage Intermediate Layer Protein (CILP) ELISA Kit | BioReagent | Detects CILP level | Research on intermediate cartilage matrix changes and degeneration | |
Cartilage inflammation/injury marker | Rat Chitinase-3-like Protein 1 (GP39) ELISA Kit | BioReagent | Detects GP39/CHI3L1-related levels | Rat cartilage injury, inflammation, and degeneration models | |
Cartilage inflammation/injury marker | Mouse Chitinase-3-like Protein 1 (CHI3L1) ELISA Kit | BioReagent | Detects mouse CHI3L1 level | Mouse osteoarthritis and cartilage inflammation research | |
Type II collagen evaluation | Human Collagen Type Ⅱ (COL2) ELISA Kit | BioReagent | Detects COL2 level | Evaluation of hyaline cartilage phenotype and cartilage matrix | |
Type II collagen evaluation | Human Collagen Type Ⅱ (Col Ⅱ) ELISA Kit | BioReagent | Detects human type II collagen | Evaluation of chondrogenic induction and cartilage repair quality | |
Type II collagen evaluation | Rat Collagen Type Ⅱ (COL2) ELISA Kit | BioReagent | Detects rat COL2 level | Rat cartilage degeneration and repair models | |
Type II collagen evaluation | Mouse Collagen Type Ⅱ (COLⅡ) ELISA Kit | BioReagent | Detects mouse COL II level | Biochemical validation of histological results in mouse cartilage | |
Type II collagen degradation | Human Cross Linked C-Telopeptide Of Type Ⅱ Collagen (CTXⅡ) ELISA Kit | BioReagent | Detects type II collagen degradation fragments | Osteoarthritis degeneration and cartilage matrix degradation evaluation | |
Type II collagen degradation | Rat Cross Linked C-Telopeptide Of Type Ⅱ Collagen (CTXⅡ) ELISA Kit | BioReagent | Detects rat CTX II | Rat OA models and drug intervention evaluation | |
Fibrosis evaluation | Collagen I Antibody | Carrier Free, ExactAb™, Azide Free, Validated, High Performance, See COA | Detects type I collagen | Evaluation of fibrocartilage, scar-like repair tissue, and abnormal fibrosis | |
Fibrosis evaluation | Human Type Ⅰ Collagen (ColⅠ) ELISA Kit | BioReagent | Detects type I collagen | Evaluation of fibrotic repair and non-hyaline cartilage-like matrix | |
Fibrosis evaluation | Rat Collagen Type Ⅰ (COL1) ELISA Kit | BioReagent | Detects rat type I collagen | Evaluation of fibrosis degree in rat cartilage repair | |
Fibrosis evaluation | Mouse Type Ⅰ collagen (ColⅠ) ELISA Kit | BioReagent | Detects mouse type I collagen | Analysis of mouse cartilage repair and fibrocartilage formation | |
Hypertrophic differentiation evaluation | Recombinant Collagen X Antibody | Recombinant, ExactAb™, Validated, See COA | Detects type X collagen | Evaluation of chondrocyte hypertrophic differentiation and pre-calcified cartilage | |
Hypertrophic differentiation evaluation | Rat Collagen Type X (COL10) ELISA Kit | BioReagent | Detects rat COL10 | Evaluation of rat cartilage hypertrophic differentiation, degeneration, and calcification tendency | |
Matrix degradation evaluation | Recombinant MMP13 Antibody | Recombinant, ExactAb™, Validated, See COA | Detects MMP13 protein | Research on cartilage matrix degradation and osteoarthritis degeneration mechanisms | |
Matrix degradation evaluation | Recombinant Human MMP13 Protein | ≥90%(SDS-PAGE) | MMP13 protein standard or functional research material | MMP13-related method validation, enzymology, or antibody control | |
Matrix degradation evaluation | Recombinant Mouse MMP13 Protein | ≥90%(SDS-PAGE) | Mouse MMP13 protein standard or control | Mechanistic research related to mouse OA models |
Safranin O-Fast Green staining is suitable for evaluating cartilage proteoglycan retention, matrix degeneration, and repair tissue properties at the tissue-structure level. In practical applications, consistency in fixation, decalcification, sectioning, staining time, and image analysis should be emphasized. GAG composition analysis, type II collagen, Aggrecan, type I collagen, type X collagen, MMP13, and other indicators should be combined to comprehensively assess cartilage degeneration or repair quality.
For more related articles, please see below:
[1] Morphological observation experiment of hyaline cartilage