Differential proteome of bone marrow mesenchymal stem cells from osteoarthritis patients

Effect of immunology biomarkers associated with hip fracture and fracture risk in older adults

Osteoporosis is a skeletal disease that can increase the risk of fractures, leading to adverse health and socioeconomic consequences. However, current clinical methods have limitations in accurately estimating fracture risk, particularly in older adults. Thus, new technologies are necessary to improve the accuracy of fracture risk estimation. In this observational study, we aimed to explore the association between serum cytokines and hip fracture status in older adults, and their associations with fracture risk using the FRAX reference tool. We investigated the use of a proximity extension assay (PEA) with Olink. We compared the characteristics of the population, functional status and detailed body composition (determined using densitometry) between groups. We enrolled 40 participants, including 20 with hip fracture and 20 without fracture, and studied 46 cytokines in their serum. After conducting a score plot and two unpaired t-tests using the Benjamini-Hochberg method, we found that Interleukin 6 (IL-6), Lymphotoxin-alpha (LT-α), Fms-related tyrosine kinase 3 ligand (FLT3LG), Colony stimulating factor 1 (CSF1), and Chemokine (C-C motif) ligand 7 (CCL7) were significantly different between fracture and non-fracture patients (p < 0.05). IL-6 had a moderate correlation with FRAX (R2 = 0.409, p < 0.001), while CSF1 and CCL7 had weak correlations with FRAX. LT-α and FLT3LG exhibited a negative correlation with the risk of fracture. Our results suggest that targeted proteomic tools have the capability to identify differentially regulated proteins and may serve as potential markers for estimating fracture risk. However, longitudinal studies will be necessary to validate these results and determine the temporal patterns of changes in cytokine profiles.

Osteogenic capacity of mesenchymal stem cells from patients with osteoporotic hip fractures in vivo

PURPOSE

Human mesenchymal stem cells (MSCs) have the ability to differentiate into bone-forming osteoblasts. The aim of this study was to elucidate if MSCs from patients with OP show a senescent phenotype and explore their bone-forming ability in vivo.

MATERIALS AND METHODS

MSCs from patients with OP and controls with osteoarthritis (OA) were implanted into the subcutaneous tissue of immunodeficient mice for histological analysis and expression of human genes by RT-PCR. The expression of senescence-associated phenotype (SASP) genes, as well as p16, p21, and galactosidase, was studied in cultures of MSCs.

RESULTS

In vivo bone formation was evaluated in 103 implants (47 OP, 56 OA). New bone was observed in 45% of the implants with OP cells and 46% of those with OA cells (p = 0.99). The expression of several bone-related genes (collagen, osteocalcin, alkaline phosphatase, sialoprotein) was also similar in both groups. There were no differences between groups in SASP gene expression, p16, and p21 expression, or in senescence-associated galactosidase activity.

CONCLUSION

Senescence markers and the osteogenic capacity in vivo of MSCs from patients with OP are not inferior to that of cells from controls of similar age with OA. This supports the interest of future studies to evaluate the potential use of autologous MSCs from OP patients in bone regeneration procedures.

Proteomic study of in vitro osteogenic differentiation of mesenchymal stem cells in high glucose condition

Patients with diabetes have been widely reported to be at an increased risk of secondary osteoporosis. Osteoporosis is caused by an imbalance in bone remodeling due to increased bone resorption and/or decreased osteoblast-dependent bone formation. In this study, mesenchymal stem cells (MSCs) were used as a disease model to determine the effects of high glucose levels on MSC-osteoblast development. The results indicated that under high glucose conditions, MSCs had reduced cell viability and increased number of β-galactosidase-positive cells. Furthermore, in vitro osteogenesis was shown to be reduced in MSCs cultured in osteogenic differentiation medium at 10, 25, and 40 mM glucose as demonstrated by Alizarin red S staining and alkaline phosphatase activity assay. Moreover, a proteomic study was performed in MSCs cultured with 25 and 40 mM glucose. The proteomic results demonstrated that 12 proteins were up- and downregulated in bone marrow-derived mesenchymal stem cells cultured with high glucose in a dose-dependent manner. The findings presented here contribute to our understanding of the mechanism of diabetes mellitus responsible for bone loss. However, the exact mechanism of action of hyperglycemia on bone deformability requires additional studies.

Articular cartilage regeneration: The role of endogenous mesenchymal stem/progenitor cell recruitment and migration

BACKGROUND

Trauma- or osteoarthritis-related cartilage damage resulted in functional decline of joints and heavy burden of public health. Recently, the reparative role of mesenchymal stem/progenitor cells (MSCs) in articular cartilage (AC) reconstruction is drawing more and more attention.

OBJECTIVE

To provide a review on (1) the locations and categories of joint-resident MSCs, (2) the regulation of chondrogenic capacities of MSCs, (3) the migratory approaches of MSCs to diseased AC and regulatory mechanisms.

METHODS

PubMed and Web of Science were searched for English-language articles related to MSC recruitment and migration for AC repair until June 2019. The presence of various MSCs in or around joints, the potential approaches to diseased AC` and the regenerative capacities of MSCs were reviewed.

RESULTS

Various intra- and peri-articular MSCs, with inherent migratory potentials, are present in multiple stem cell niches in or around joints. The recruitment and migration of joint-resident MSCs play crucial roles in endogenous AC repair. Multiple recruiting signals, such as chemokines, growth factors, etc., emerge during the development of AC diseases and participate in the regulation of MSC mobilization. Motivated MSCs could migrate into cartilage lesions and then exert multiple reparative potentials, including extracellular matrix (ECM) reconstruction and microenvironment modulation.

CONCLUSION

In general, AC repair based on endogenous MSC recruitment and migration is a feasible strategy, and a promising research field. Furthermore, endogenous AC repair mediated by native MSCs would provide new opportunities to efficient preventative or therapeutic options for AC diseases.

Do immune cells lead the way in subchondral bone disturbance in osteoarthritis?

Osteoarthritis (OA) is a whole-joint disorder, and non-cartilage articular pathologies, e.g. subchondral bone disturbance, contribute substantially to the onset and progression of the disease. In the early stage of OA, abnormal mechanical loading leads to micro-cracks or micro-fractures that trigger a reparative process with angiogenesis and inflammatory response. With the progression of disease, cystic lesion, sclerosis and osteophytosis occur at tissue level, and osteoblast dysfunction at cellular level. Osteoblasts derived from OA sclerotic bone produce increased amount of type I collagen with aberrant Col1A1/A2 ratio and poor mineralization capability. The coupling mechanism of bone resorption with formation is also impaired with elevated osteoclastic activities. All these suggest a view that OA subchondral bone presents a defective fracture repair process in a chronic course. It has been found that T and B cells, the major effectors in the adaptive immunity, take part in the hard callus formation at fracture site in addition to the initial phase of haematoma and inflammation. Infiltration of lymphocytes could interplay with osteoclasts and osteoblasts via a direct physical cell-to-cell contact. Several lines of evidence have consistently shown the involvement of T and B cells in osteoclastogenesis and bone erosion in arthritic joints. Yet the biological link between immune cells and osteoblastic function remains ambiguous. This review will discuss the current knowledge regarding the role of immune cells in bone remodelling, and address its implications in emerging basic and clinical investigations into the pathogenesis and management of subchondral bone pathologies in OA.

Deformability of Human Mesenchymal Stem Cells Is Dependent on Vimentin Intermediate Filaments

Mesenchymal stem cells (MSCs) are being studied extensively due to their potential as a therapeutic cell source for many load-bearing tissues. Compression of tissues and the subsequent deformation of cells are just one type physical strain MSCs will need to withstand in vivo. Mechanotransduction by MSCs and their mechanical properties are partially controlled by the cytoskeleton, including vimentin intermediate filaments (IFs). Vimentin IF deficiency has been tied to changes in mechanosensing and mechanical properties of cells in some cell types. However, how vimentin IFs contribute to MSC deformability has not been comprehensively studied. Investigating the role of vimentin IFs in MSC mechanosensing and mechanical properties will assist in functional understanding and development of MSC therapies. In this study, we examined vimentin IFs' contribution to MSCs' ability to deform under external deformation using RNA interference. Our results indicate that a deficient vimentin IF network decreases the deformability of MSCs, and that this may be caused by the remaining cytoskeletal network compensating for the vimentin IF network alteration. Our observations introduce another piece of information regarding how vimentin IFs are involved in the complex role the cytoskeleton plays in the mechanical properties of cells.

Functional genomics in osteoarthritis: Past, present, and future

Osteoarthritis (OA) is a common complex disease of high public health burden. OA is characterized by the degeneration of affected joints leading to pain and reduced mobility. Over the last few years, several studies have focused on the genomic changes underpinning OA. Here, we provide a comprehensive overview of genome-wide, non-hypothesis-driven functional genomics (methylation, gene, and protein expression) studies of knee and hip OA in humans. Individual studies have generally been limited in sample size and hence power, and have differed in their approaches; nonetheless, some common themes have started to emerge, notably the role played by biological processes related to the extracellular matrix, immune response, the WNT pathway, angiogenesis, and skeletal development. Larger-scale studies and streamlined, robust methodologies will be needed to further elucidate the biological etiology of OA going forward. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1105-1110, 2016.

Comparison of molecular mechanisms of rheumatoid arthritis and osteoarthritis using gene microarrays

The present study aimed to compare the molecular mechanisms of rheumatoid arthritis (RA) and osteoarthritis (OA). The microarray dataset no. GSE29746 was downloaded from Gene Expression Omnibus. After data pre‑processing, differential expression analysis between the RA group and the control, as well as between the OA group and the control was performed using the LIMMA package in R and differentially expressed transcripts (DETs) with |log2fold change (FC)|>1 and P<0.01 were identified. DETs screened from each disease group were then subjected to functional annotation using DAVID. Next, DETs from each group were used to construct individual interaction networks using the BIND database, followed by sub‑network mining using clusterONE. Significant functions of nodes in each sub‑network were also investigated. In total, 19 and 281 DETs were screened from the RA and OA groups, respectively, with only six common DETs. DETs from the RA and OA groups were enriched in 8 and 130 gene ontology (GO) terms, respectively, with four common GO terms, of which to were associated with phospholipase C (PLC) activity. In addition, DETs screened from the OA group were enriched in immune response‑associated GO terms, and those screened from the RA group were largely associated with biological processes linked with the cell cycle and chromosomes. Genes involved in PLC activity and its regulation were indicated to be altered in RA as well as in OA. Alterations in the expression of cell cycle‑associated genes were indicated to be linked with the occurrence of OA, while genes participating in the immune response were involved in the occurrence of RA.

Subchondral bone proteomics in osteoarthritis: Current status and perspectives

Osteoarthritis (OA) is the most common degenerative joint disorder. OA was conceived as a “wear and tear” problem of articular cartilage, yet there is a lack of treatment options to delay or rescue articular cartilage degeneration once it is established. Actually, the degradation of articular cartilage is related to a complex network of biochemical pathways involving the diffusion of catabolic factors within and between different joint tissues and particularly bone and cartilage. Advanced proteomics technology provides a powerful tool to allow us to build up a library of such factors. Factors that govern the bone-cartilage interplay could be the candidate diagnostic biomarkers and therapeutic targets for OA. Currently, a growing body of proteomic studies has been done to unveil a number of inflammatory cytokines, proteases, and cartilaginous matrix cleavages in the blood serum, synovial fluid, and articular cartilage from OA patients. Little information is available regarding the protein profiles of disturbances at subchondral bone in the pathophysiology of OA. The technical difficulties in protein extraction from tissues particularly bone and quantitative analyses of protein profile are discussed; cellular proteomics of the defective osteoblasts and secretomics for the osteoblasts–chondrocytes crosstalk are proposed to supplement the information obtained from the bone tissue proteomics.

Selected reaction monitoring assays in mesenchymal stem cells from osteoarthritis patients

Osteoarthritis (OA) is considered the most prevalent form of arthritis. The aim of this study was to verify potential protein OA biomarkers by applying Selected Reaction Monitoring (SRM) assays to protein extracts obtained from Bone Marrow-Mesenchymal Stem Cells (BM-MSCs) isolated from OA patients.

BM aspirates were obtained from the femoral channel of OA patients at the time of surgery and from the femoral channel of hip fracture subjects without OA during hip joint replacement surgery for the treatment of subcapital fracture.

SRM results verified the differential expression of several protein biomarkers in BM-MSCs from OA patients.

Global proteomic signature of undifferentiated human bone marrow stromal cells: evidence for donor-to-donor proteome heterogeneity

The clinical application of human bone marrow stromal cells (hBMSCs) largely depends on their capacity to expand in vitro. We have conducted a comprehensive comparative proteomic analysis of culture-expanded hBMSCs obtained from different human donors. The data reveal extensive donor-to-donor proteomic heterogeneity. Processing and database-searching of the tandem MS data resulted in a most comprehensive to date proteomic dataset for hBMSC. A total of 7753 proteins including 712 transcription and translation regulators, 384 kinases, 248 receptor proteins, and 29 cytokines were confidently identified. The proteins identified are mainly nuclear (43.2%) and the share of proteins assigned to more than one subcellular location constitutes 10% of the identified proteome. Bioinformatics tools (IPA, DAVID, and PANTHER) were used to annotate proteins with respect to cellular locations, functions, and other physicochemical characteristics. We also compared the proteomic profile of hBMSCs to recently compiled datasets for human and mouse pluripotent stem cells. The result shows the extent of similarity between the three cell populations and also identified 253 proteins expressed uniformly by all lines of hBMSCs but not reported in the proteomic datasets of the two pluripotent stem cells. Overall, the proteomic database reported in this paper can serve as a reference map for extensive evaluation of hBMSC to explain their biology as well as identify possible marker candidates for further evaluation.

Proteomic analysis of synovial fluid from the osteoarthritic knee: comparison with transcriptome analyses of joint tissues

OBJECTIVE

The pathophysiology of the most common joint disease, osteoarthritis (OA), remains poorly understood. Since synovial fluid (SF) bathes joint cartilage and synovium, we reasoned that a comparative analysis of its protein constituents in health and OA could identify pathways involved in joint damage. We undertook this study to perform a proteomic analysis of knee SF from OA patients and control subjects and to compare the results to microarray expression data from cartilage and synovium.

METHODS

Age-matched knee SF samples from 10 control subjects, 10 patients with early-stage OA, and 10 patients with late-stage OA were compared using 2-dimensional difference-in-gel electrophoresis and mass spectrometry (MS). MS with a multiplexed peptide selected reaction monitoring assay was used to confirm differential expression of a subset of proteins in an independent OA patient cohort. Proteomic results were analyzed by Ingenuity Pathways Analysis and compared to published synovial tissue and cartilage messenger RNA profiles.

RESULTS

Sixty-six proteins were differentially present in healthy and OA SF. Three major pathways were identified among these proteins: the acute-phase response signaling pathway, the complement pathway, and the coagulation pathway. Differential expression of 5 proteins was confirmed by selected reaction monitoring assay. A focused analysis of transcripts corresponding to the differentially present proteins indicated that both synovial and cartilage tissues may contribute to the OA SF proteome.

CONCLUSION

Proteins involved in the acute-phase response signaling pathway, the complement pathway, and the coagulation pathway are differentially regulated in SF from OA patients, suggesting that they contribute to joint damage. Validation of these pathways and their utility as biomarkers or therapeutic targets in OA is warranted.

Application for proteomic techniques in studying osteoarthritis: a review

After the genomic era, proteomic corresponds to a wide variety of techniques that study the protein content of cells, tissue, or organism and that allow the isolation of protein of interest. It offers the choice between gel-based and gel-free methods or shotgun proteomics. Applications of proteomic technology may concern three principal objectives in several biomedical or clinical domains of research as in osteoarthritis: (i) to understand the physiopathology or underlying mechanisms leading to a disease or associated with a particular model, (ii), to find disease-specific biomarker, and (iii) to identify new therapeutic targets. This review aimed at gathering most of the data regarding the proteomic techniques and their applications to osteoarthritis research. It also reported technical limitations and solutions, as for example for sample preparation. Proteomics open wide perspectives in biochemical research but many technical matters still remain to be solved.