Circ_0045714/miR-331-3p interaction affects IL-1β-evoked human articular chondrocyte injury through regulating PIK3R3 in a ceRNA regulatory cascade

BACKGROUND

Osteoarthritis (OA) is characterized by joint pain and joint function limitation. Hsa_circ_0045714 (circ_0045714) is a novel OA-related circular RNA. However, its repertoire remains to be further clarified in joint chondrocytes.

METHODS

RNA and protein expression levels and inflammatory factor levels were detected by real-time quantitative polymerase chain reaction, western blotting and enzyme-linked immunosorbent assay. Cell proliferation and apoptosis were determined by colony formation assay, cell counting kit-8 assay and apoptosis assay. Direct interaction was predicted by bioinformatics method and confirmed by dual-luciferase reporter assay.

RESULTS

Expression of circ_0045714 and phosphoinositide-3-kinase (PI3K) regulatory subunit 3 (PIK3R3) was declined, and microRNA (miR)-331-3p was promoted in knee articular cartilages and cells from OA patients, as well as interleukin (IL)-1β-challenged human articular chondrocytes (HAC) cell line. In stimulation of IL-1β, HAC cells showed a loss of colony formation ability, cell viability and expression of Bcl-2 and Collagen II, allied with an increase in apoptosis rate and levels of IL-6, IL-8 and tumor necrosis factor-α, Bcl-2-associated X protein, cleaved caspase-3, and ADAM with thrombospondin motif-5. Noticeably, overexpressing circ_0045714 and inhibiting miR-331-3p could suppress IL-1β-evoked these effects, and both were through up-regulating PIK3R3, a key gene in PI3K/AKT signaling pathway. Mechanically, circ_0045714 functioned as competing endogenous RNA (ceRNA) for miR-331-3p and further regulated expression of the downstream target gene PIK3R3.

CONCLUSION

There was a novel circ_0045714/miR-331-3p/PIK3R3 ceRNA axis in HAC, and its inhibition might be one mechanism of HAC injury in OA.

Red panda: a novel method for detecting variants in single-cell RNA sequencing

BACKGROUND

Single-cell sequencing enables us to better understand genetic diseases, such as cancer or autoimmune disorders, which are often affected by changes in rare cells. Currently, no existing software is aimed at identifying single nucleotide variations or micro (1-50 bp) insertions and deletions in single-cell RNA sequencing (scRNA-seq) data. Generating high-quality variant data is vital to the study of the aforementioned diseases, among others.

RESULTS

In this study, we report the design and implementation of Red Panda, a novel method to accurately identify variants in scRNA-seq data. Variants were called on scRNA-seq data from human articular chondrocytes, mouse embryonic fibroblasts (MEFs), and simulated data stemming from the MEF alignments. Red Panda had the highest Positive Predictive Value at 45.0%, while other tools-FreeBayes, GATK HaplotypeCaller, GATK UnifiedGenotyper, Monovar, and Platypus-ranged from 5.8-41.53%. From the simulated data, Red Panda had the highest sensitivity at 72.44%.

CONCLUSIONS

We show that our method provides a novel and improved mechanism to identify variants in scRNA-seq as compared to currently existing software. However, methods for identification of genomic variants using scRNA-seq data can be still improved.

Regulation of Extracellular Matrix Synthesis by Shell Extracts from the Marine Bivalve Pecten maximus in Human Articular Chondrocytes- Application for Cartilage Engineering

The shells of the bivalve mollusks are organo-mineral structures predominantly composed of calcium carbonate, but also of a minor organic matrix, a mixture of proteins, glycoproteins, and polysaccharides. These proteins are involved in mineral deposition and, more generally, in the spatial organization of the shell crystallites in well-defined microstructures. In this work, we extracted different organic shell extracts (acid-soluble matrix, acid-insoluble matrix, water-soluble matrix, guanidine HCl/EDTA-extracted matrix, referred as ASM, AIM, WSM, and EDTAM, respectively) from the shell of the scallop Pecten maximus and studied their biological activities on human articular chondrocytes (HACs). We found that these extracts differentially modulate the biological activities of HACs, depending on the type of extraction and the concentration used. Furthermore, we showed that, unlike ASM and AIM, WSM promotes maintenance of the chondrocyte phenotype in monolayer culture. WSM increased the expression of chondrocyte-specific markers (aggrecan and type II collagen), without enhancing that of the main chondrocyte dedifferentiation marker (type I collagen). We also demonstrated that WSM could favor redifferentiation of chondrocyte in collagen sponge scaffold in hypoxia. Thus, this study suggests that the organic matrix of Pecten maximus, particularly WSM, may contain interesting molecules with chondrogenic effects. Our research emphasizes the potential use of WSM of Pecten maximus for cell therapy of cartilage.

Measuring clinically relevant endpoints in a serum-free, three-dimensional, primary cell culture system of human osteoarthritic articular chondrocytes

Osteoarthritis (OA) is characterized by degeneration of articular cartilage within the joint, inflammation and pain. The purpose of this study was to develop a primary, serum free cell culture system of human osteoarthritic articular chondrocytes (HOACs) with which to study manifestations of the disease process. Joint tissues were obtained from OA patients undergoing total knee arthroplasty (TKA). HOACs isolated from the femoral condyles and tibial plateau of the same side were combined, plated in three-dimensional, alginate beads and cultured for five days in serum, hormone and protein free medium. More living cells were obtained from the femoral condyles than the tibial plateau. The optimal plating density was 2.5 × 10⁶ cells/ml of alginate. The amounts of DNA, RNA, proteoglycans and total collagen were similar in cultures prepared from the sides of least and greatest pathology. More type 1 than type 2 collagen was detected in the medium on days 2 and 5. A greater percentage of type 1 than type 2 collagen was degraded. The inflammatory cytokine interleukin-1 beta was present in the medium and alginate associated matrix. Although variation in the metabolic profiles between subjects was observed, HOACs from all patients continued to reflect the OA phenotype for five days in culture. This serum free, three-dimensional primary culture system of HOACs provides a platform with which to measure clinically relevant endpoints of OA and screen potential disease modifying OA therapeutics.

Direct quantification of dual protein adsorption dynamics in three dimensional systems in presence of cells

Understanding the composition of the adsorbed protein layer on a biomaterial surface is of an extreme importance as it directs the primary biological response. Direct detection using labeled proteins and indirect detection based on enzymatic assays or changes to mass, refractive index or density of a surface have been so far established. Nevertheless, using current methodologies, detection of multiple proteins simultaneously and particularly in a three-dimensional (3D) substrates is challenging, with the exception of radiolabeling. Here using fluorescence molecular tomography (FMT), we present a non-destructive and versatile approach to quantify adsorption of multiple proteins within 3D environments and reveal the dynamics of adsorption of human serum albumin (HSA) and fibrinogen (Fib) on 3D polymeric scaffold. Furthermore, we show that serum starved human articular chondrocytes in 3D environment preferentially uptake HSA over Fib and to our knowledge this represents the first example of direct visualization and quantification of protein adsorption in a 3D cell culture system.

STATEMENT OF SIGNIFICANCE

The biomaterial surface upon exposure to biological fluids is covered by a layer of proteins, which is modified over a period of time and dictates the fate of the biomaterial. In this study, we present and validate a new methodology for quantification of protein adsorption on to a three-dimensional polymer scaffold from unitary and binary systems, using fluorescence molecular tomography, an optical trans-illumination technique with picomolar sensitivity. In additional to being able to follow behavior of two proteins simultaneously, this methodology is also suitable for studying protein uptake in cells situated in a polymer environment. The ability to follow protein adsorption/uptake in a continuous manner opens up new possibilities to study the role of serum proteins in biomaterial compatibility.

Isolation and characterization of human articular chondrocytes from surgical waste after total knee arthroplasty (TKA)

BACKGROUND

Cartilage tissue engineering is a fast-evolving field of biomedical engineering, in which the chondrocytes represent the most commonly used cell type. Since research in tissue engineering always consumes a lot of cells, simple and cheap isolation methods could form a powerful basis to boost such studies and enable their faster progress to the clinics. Isolated chondrocytes can be used for autologous chondrocyte implantation in cartilage repair, and are the base for valuable models to investigate cartilage phenotype preservation, as well as enable studies of molecular features, nature and scales of cellular responses to alterations in the cartilage tissue.

METHODS

Isolation and consequent cultivation of primary human adult articular chondrocytes from the surgical waste obtained during total knee arthroplasty (TKA) was performed. To evaluate the chondrogenic potential of the isolated cells, gene expression of collagen type 2 (COL2), collagen 1 (COL1) and aggrecan (ACAN) was evaluated. Immunocytochemical staining of all mentioned proteins was performed to evaluate chondrocyte specific production.

RESULTS

Cartilage specific gene expression of COL2 and ACAN has been shown that the proposed protocol leads to isolation of cells with a high chondrogenic potential, possibly even specific phenotype preservation up to the second passage. COL1 expression has confirmed the tendency of the isolated cells dedifferentiation into a fibroblast-like phenotype already in the second passage, which confirms previous findings that higher passages should be used with care in cartilage tissue engineering. To evaluate the effectiveness of our approach, immunocytochemical staining of the evaluated chondrocyte specific products was performed as well.

DISCUSSION

In this study, we developed a protocol for isolation and consequent cultivation of primary human adult articular chondrocytes with the desired phenotype from the surgical waste obtained during TKA. TKA is a common and very frequently performed orthopaedic surgery during which both femoral condyles are removed. The latter present the ideal source for a simple and relatively cheap isolation of chondrocytes as was confirmed in our study.

Effect of hydrogen sulfide sources on inflammation and catabolic markers on interleukin 1β-stimulated human articular chondrocytes

OBJECTIVE

Hydrogen sulfide (H2S), the third gasotransmitter together with NO and CO, is emerging as a regulator of inflammation. To test if it might offer therapeutic value in the treatment of osteoarthritis (OA) we evaluated the effects of two exogenous sources of H2S, NaSH and GYY4137, on inflammation and catabolic markers that characterize OA.

METHOD

Human chondrocytes (CHs) were isolated from OA tissue. Cells were stimulated with a pro-inflammatory cytokine (interleukin-1β, IL1β, 5 ng/ml) and the ability of the two H2S sources to ameliorate its effects on the cells was tested. Nitric oxide (NO) production was quantified through the Griess reaction. Protein levels of inducible NO synthase (NOS2) and matrix metalloproteinase 13 (MMP13) were visualized through immunocytochemistry (ICC). Relative mRNA expression was quantified with qRT-PCR. Prostaglandin-2 (PGE-2), interleukin 6 (IL6) and MMP13 levels were measured with specific EIAs. NFκB nuclear translocation was visualized with immunofluorescence.

RESULTS

Both H2S sources led to significant reductions in NO, PGE-2, IL6 and MMP13 released by the cells and at the protein level. This was achieved by downregulation of relevant genes involved in the synthesis routes of these molecules, namely NOS2, cyclooxigenase-2 (COX2), prostaglandin E synthase (PTGES), IL6 and MMP13. NFκB nuclear translocation was also reduced.

CONCLUSION

NaSH and GYY4137 show anti-inflammatory and anti-catabolic properties when added to IL1β activated osteoarthritic CHs. Supplementation with exogenous H2S sources can regulate the expression of relevant genes in OA pathogenesis and progression, counteracting IL1β pro-inflammatory signals that lead to cartilage destruction in part by reducing NFκB activation.