Primary culture of chondrocytes after collagenase IA or II treatment of articular cartilage from elderly patients undergoing arthroplasty

Dual Enzyme Sequential Digestion Protocol for Isolation of Human Primary Chondrocytes From the Articular Cartilage Derived From Knee Osteoarthritis Patients

Introduction:

Majority of available protocols for isolation of chondrocytes from articular cartilage tissue rely on the enzymatic digestion of the tissue by collagenase type 2. The yield of chondrocytes in such protocols is low. Herein, we designed a novel indigenous sequential digestion by dual enzyme Pronase and Collagenase Type 1 for isolating human Chondrocytes from articular cartilage.

Methods:

Articular cartilage of Osteoarthritis (OA) patients undergoing total knee replacement were collected for the isolation of chondrocyte cells and subjected to sequential digestion by Pronase for three hours followed by Collagenase 1 overnight. Pellet of cells collected after digestion was plated on culture flask in 5% CO2 incubator.

Results:

From day three onwards, round to elongated cells adhered to the flask were visible which developed into elongated cell population of homogenous morphology, expressed Aggrecan (Agg), Collagen 2a (Col2a) and SRY-box transcription factor (Sox9) and had chondrogenic differentiation similar to a commercially available healthy chondrocyte. These cells were negative for Alizarin red stain, thus confirming the purity of chondrocytes.

Conclusion:

We have successfully established a sequential dual enzyme digestion-based culture technique for isolating the human chondrocytes from the articular cartilage biopsy derived from OA knee joints.

Insufficiency of collagenases in establishment of primary chondrocyte culture from cartilage of elderly patients receiving total joint replacement

Background Collagenases are frequently used in chondrocyte isolation from articular cartilage. However, the sufficiency of this enzyme in establishing primary human chondrocyte culture remains unknown. Methods Cartilage slices shaved from femoral head or tibial plateau of patients receiving total joint replacement surgery (16 hips, 8 knees) were subjected to 0.02% collagenase IA digestion for 16 h with (N = 19) or without (N = 5) the pre-treatment of 0.4% pronase E for 1.5 h. Chondrocyte yield and viability were compared between two groups. Chondrocyte phenotype was determined by the expression ratio of collagen type II to I. The morphology of cultured chondrocytes was monitored with a light microscope.Results Cartilage with pronase E pre-treatment yielded significantly higher chondrocytes than that without the pre-treatment (3,399 ± 1,637 cells/mg wet cartilage vs. 1,895 ± 688 cells/mg wet cartilage; P = 0.0067). Cell viability in the former group was also significantly higher than that in the latter (94% ± 2% vs. 86% ± 6%; P = 0.03). When cultured in monolayers, cells from cartilage with pronase E pre-treatment grew in a single plane showing rounded shape while cells from the other group grew in multi-planes and exhibited irregular shape. The mRNA expression ratio of collagen type II to I was 13.2 ± 7.5 in cells isolated from cartilage pre-treated with pronase E, indicating a typical chondrocyte phenotype. Conclusions Collagenase IA was not sufficient in establishing primary human chondrocyte culture. Cartilage must be treated with pronase E prior to collagenase IA application.

LINC01534/miR-135b-5p/PTPRT axis regulates inflammatory response in loosening total hip replacement via modulating NF-κB signaling pathway

Aseptic loosening after total hip replacement brings adverse health outcomes and increased risk for complications. The resorptive activity of inflammatory cells activated by the presence of wear-generated debris plays a critical role in debris-induced osteolysis. Previous studies indicate that the abnormally expressed LINC01534 plays a critical role in inflammatory responses. In this study, we aimed to elucidate the functional role and underlying mechanism of LINC01534 in debris-induced osteolysis. We first confirmed that LINC01534 was highly expressed in hip cartilage tissues from aseptic loosening patients. By using an IL-1β-induced inflammation model mimicking debris-induced osteolysis, we demonstrated that LINC01534 promoted IL-1β-induced inflammatory response in hip chondrocytes. Knockdown of LINC01534 inhibited the expression of inflammatory IL-6, IL-8, and TNF-α in hip chondrocytes. Our results showed that LINC01534 functioned as a competing endogenous RNA (ceRNA) by sponging miR-135b-5p in hip chondrocytes. Moreover, bioinformatics analysis and luciferase reporter assay demonstrated that CCHC-Type Zinc Finger Nucleic Acid Binding Protein (PTPRT) is a downstream target of miR-135b-5p. Knockdown of PTPRT attenuated the IL-1β-induced inflammatory responses in hip chondrocytes. In addition, we revealed that inhibition of miR-135b-5p or overexpression of PTPRT could antagonize the effects of LINC01534 knockdown on inflammation attenuation in hip chondrocytes. Mechanistically, we demonstrated that LINC01534/miR-135b-5p/PTPRT axis regulated the NF-κB signaling pathway in hip chondrocytes. Taken together, our findings suggest that LINC01534/miR-135b-5p/PTPRT axis might be a valuable therapeutic target for the treatment of debris-induced osteolysis.