The Absence of Detectable ADAMTS-4 (Aggrecanase-1) Activity in Synovial Fluid Is a Predictive Indicator of Autologous Chondrocyte Implantation Success

Proteomic Analyses of Autologous Chondrocyte Implantation Plasma Highlight Cartilage Acidic Protein 1 as a Candidate for Preclinical Screening

BACKGROUND

Stratification is required to ensure that only patients likely to benefit receive autologous chondrocyte implantation (ACI). It would be advantageous to identify biomarkers to predict ACI outcome that are measurable in blood, avoiding the need for an invasive synovial fluid harvest.

PURPOSE

To assess if proteomic analyses can be used to identify novel candidate blood biomarkers in individuals who respond well or poorly to ACI.

STUDY DESIGN

Controlled laboratory study.

METHODS

Isobaric tagging for relative and absolute quantitation (iTRAQ) mass spectrometry was used to assess the proteome in plasma pooled from ACI responders (mean Lysholm improvement after ACI, 33; n = 10) or nonresponders (mean, -13; n = 10), collected at the time of surgery for cartilage harvest (stage 1) or implantation of culture-expanded chondrocytes (stage 2). An alternative proteomic method, label-free quantitation liquid chromatography-tandem mass spectrometry, was used to analyze plasma samples (majority matched to iTRAQ) individually. Differentially abundant proteins (±2.0-fold) were analyzed from both proteomic data sets, and markers of interest identified via pooled iTRAQ were validated via immunoassay of individual samples.

RESULTS

Protein differences could be detected in the plasma preoperatively between ACI responders and nonresponders (16 proteins; ≥±2.0-fold change; P < .05) using iTRAQ proteomics. The most pronounced plasma proteome shift was evident in response to stage 1 surgery in ACI nonresponders, with 48 proteins being differentially abundant between the procedures. Label-free quantitation liquid chromatography-tandem mass spectrometry analysis of these same plasma samples (nonpooled) resulted in very few proteins being identified that were significantly differentially abundant. However, this work highlighted cartilage acidic protein 1 as being increased preoperatively in nonresponders as compared with responders.

CONCLUSIONS

This study is the first to use proteomic techniques to profile the plasma of individuals treated with ACI. Despite iTRAQ analysis of pooled plasmas indicating that there are differences in the plasma proteome between responders and nonresponders to ACI, these findings were not replicated when assessed using an alternative nonpooled technique. This study highlights some of the difficulties in profiling the plasma proteome in an attempt to identify novel biomarkers. Regardless, cartilage acidic protein 1 has been identified as a protein candidate, which is detectable in plasma and can predict outcome to ACI before treatment.

CLINICAL RELEVANCE

Candidate plasma protein biomarkers identified in this study have the potential to help determine which patients will be best suited to treatment with ACI.

Identification of Candidate Synovial Fluid Biomarkers for the Prediction of Patient Outcome After Microfracture or Osteotomy

BACKGROUND

Biomarkers are needed to predict clinical outcomes for microfracture and osteotomy surgeries to ensure patients can be better stratified to receive the most appropriate treatment.

PURPOSE

To identify novel biomarker candidates and to investigate the potential of a panel of protein biomarkers for the prediction of clinical outcome after treatment with microfracture or osteotomy.

STUDY DESIGN

Descriptive laboratory study.

METHODS

To identify novel candidate biomarker proteins, we used label-free quantitation after liquid chromatography-tandem mass spectrometry of dynamic range-compressed synovial fluids (SFs) from individuals who responded excellently or poorly (based on change in Lysholm score) to microfracture (n = 6) or osteotomy (n = 7). Biomarkers that were identified in this proteomic analysis or that relate to osteoarthritis (OA) severity or have predictive value in another early OA therapy (autologous cell implantation) were measured in the SF of 19 and 13 patients before microfracture or osteotomy, respectively, using commercial immunoassays, and were normalized to urea. These were aggrecanase-1 (ADAMTS-4), cartilage oligomeric matrix protein (COMP), hyaluronan (HA), lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), matrix metalloproteinase 1 and 3, soluble CD14, S100 calcium binding protein A13, and 14-3-3 protein theta (YWHAQ). Levels of COMP and HA were also measured in the plasma of these patients. To find predictors of postoperative function, multivariable regression analyses were performed.

RESULTS

Proteomic analyses highlighted YWHAQ and LYVE-1 as being differentially abundant between the clinical responders/improvers and nonresponders after microfracture. A linear regression model after backward variable selection could relate preoperative concentrations of SF proteins (HA, YWHAQ, LYVE-1), activity of ADAMTS-4, and patient demographic characteristics (smoker status and sex) with Lysholm score 12 months after microfracture. Further, a generalized linear model with elastic net penalization indicated that lower preoperative activity of ADAMTS-4 in SF, being a nonsmoker, and being younger at the time of operation were indicative of a higher postoperative Lysholm score (improved joint function) after osteotomy surgery.

CONCLUSION

We have identified biomarkers and generated regression models with the potential to predict clinical outcome in patients treated with microfracture or osteotomy of the knee.

CLINICAL RELEVANCE

Candidate protein biomarkers identified in this study have the potential to help determine which patients will be best suited to treatment with microfracture or osteotomy.

Survival Analysis of Revision Autologous Chondrocyte Implantation for Failed ACI

BACKGROUND

Autologous chondrocyte implantation (ACI) provides a successful outcome for treating articular cartilage lesions. However, there have been very few reports on the clinical outcomes of revision ACI for failed ACI.

PURPOSE

To evaluate clinical outcomes in patients who underwent revision ACI of the knee for failure of an initial ACI and to determine the factors affecting the survival rate.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A review of a prospectively collected data set was performed from patients who underwent revision ACI of the knee for failure of an initial ACI between 1995 and 2014 by a single surgeon. The authors evaluated 53 patients (53 knees; mean age, 38 years) over a mean 11.2-year follow-up (range, 2-20). A total of 62 cartilage lesions were treated for failed graft lesions after an initial ACI, and 31 new cartilage lesions were treated at revision ACI, as there was progression of disease. Overall, 93 cartilage lesions (mean, 1.8 lesions per knee) with a total surface area of 7.4 cm² (range, 2.5-18 cm²) per knee were treated at revision ACI. Survival analysis was performed with the Kaplan-Meier method, with ACI graft failure or conversion to a prosthetic arthroplasty as the endpoint. The modified Cincinnati Knee Rating Scale, Western Ontario and McMaster Universities Osteoarthritis Index, visual analog scale, and 36-Item Short Form Health Survey were used to evaluate clinical outcomes. Patients also self-reported knee function and satisfaction. Standard radiographs were evaluated with Kellgren-Lawrence grades.

RESULTS

Survival rates were 71% and 53% at 5 and 10 years, respectively. Survival subanalysis revealed a trend that patients without previous cartilage repair procedures before an initial ACI had better survival rates than those with such procedures (81% vs 62% at 5 years, 64% vs 42% at 10 years, P = .0958). Patients with retained grafts showed significant improvement in pain and function, with a high level of satisfaction. At a mean 5.1 years postoperatively, 18 of 27 successful knees were radiographically assessed with no significant osteoarthritis progression. Outcomes for 26 patients were considered failures (mean, 4.9 years postoperatively), in which 15 patients had prosthetic arthroplasty (mean, 4.6 years) and the other 11 patients had revision cartilage repair (mean, 5.4 years) and thus could maintain their native knees.

CONCLUSION

Results of revision ACI for patients who failed ACI showed acceptable clinical outcomes. Revision ACI may be an option for young patients after failed initial ACI, particularly patients without previous cartilage repair procedures and those who desire to maintain their native knees.

Osteoarthritis year in review 2018: biomarkers (biochemical markers)

OBJECTIVE

The aim of this narrative review is to summarize important findings from biochemical marker studies relevant to osteoarthritis (OA) in the context of new discoveries and clinical and scientific need.

DESIGN

We conducted a systematic search of electronic medical databases (Embase, Medline, Web of Science, Cochrane central) between 01-03-2017 and 31-03-2018. The search was restricted to human studies, English language and full text available publications while reviews were excluded. Only papers describing protein based biomarkers measured in human body fluids (blood, urine and synovial fluid (SF)) were included. Of the 992 papers, 86 were reviewed here, with inclusion primarily based on relevance to OA biochemical markers.

RESULTS

This review highlights a selection of studies based on their quality and perceived importance to the field mainly including those that¹ evaluate prognostic value of biomarkers for OA progression (i.e., biomarkers reflecting change in composition of joint tissues and biomarkers of inflammation)², help in assessment of intervention efficacy, and³ are innovative and uncover new candidate biomarkers, or use new approaches in biomarker discovery.

CONCLUSIONS

Key findings and implications for possible clinical utility of biochemical markers are summarized and discussed. Given the paucity of robust biomarkers within the field, and the heterogeneity of the condition, enormous works are needed for development and validation of novel and clinically applicable biomarkers to reduce the impact of this highly prevalent and debilitating condition.

In vitro chondrogenic potency of surplus chondrocytes from autologous transplantation procedures does not predict short-term clinical outcomes

BACKGROUND

Autologous chondrocyte implantation (ACI) has been used over the last two decades to treat focal cartilage lesions aiming to delay or prevent the onset of osteoarthritis; however, some patients do not respond adequately to the procedure. A number of biomarkers that can forecast the clinical potency of the cells have been proposed, but evidence for the relationship between in vitro chondrogenic potential and clinical outcomes is missing. In this study, we explored if the ability of cells to make cartilage in vitro correlates with ACI clinical outcomes. Additionally, we evaluated previously proposed chondrogenic biomarkers and searched for new biomarkers in the chondrocyte proteome capable of predicting clinical success or failure after ACI.

METHODS

The chondrogenic capacity of chondrocytes derived from 14 different donors was defined based on proteoglycans staining and visual histological grading of tissues generated using the pellet culture system. A Lysholm score of 65 two years post-ACI was used as a cut-off to categorise "success" and "failure" clinical groups. A set of predefined biomarkers were investigated in the chondrogenic and clinical outcomes groups using flow cytometry and qPCR. High-throughput proteomics of cell lysates was used to search for putative biomarkers to predict chondrogenesis and clinical outcomes.

RESULTS

Visual histological grading of pellets categorised donors into "high" and "low" chondrogenic groups. Direct comparison between donor-matched in vitro chondrogenic potential and clinical outcomes revealed no significant associations. Comparative analyses of selected biomarkers revealed that expression of CD106 and TGF-β-receptor-3 was enhanced in the low chondrogenic group, while expression of integrin-α1 and integrin-β1 was significantly upregulated in the high chondrogenic group. Additionally, increased surface expression of CD166 was observed in the clinical success group, while the gene expression of cartilage oligomeric matrix protein was downregulated. High throughput proteomics revealed no differentially expressed proteins from success and failure clinical groups, whereas seven proteins including prolyl-4-hydroxylase 1 were differentially expressed when comparing chondrogenic groups.

CONCLUSION

In our limited material, we found no correlation between in vitro cartilage-forming capacity and clinical outcomes, and argue on the limitations of using the chondrogenic potential of cells or markers for chondrogenesis as predictors of clinical outcomes.

Fibrin-hyaluronic acid hydrogel-based delivery of antisense oligonucleotides for ADAMTS5 inhibition in co-delivered and resident joint cells in osteoarthritis

To date no disease-modifying drugs for osteoarthritis (OA) are available, with treatment limited to the use of pain killers and prosthetic replacement. The ADAMTS (A Disintegrin and Metallo Proteinase with Thrombospondin Motifs) enzyme family is thought to be instrumental in the loss of proteoglycans during cartilage degeneration in OA, and their inhibition was shown to reverse osteoarthritic cartilage degeneration. Locked Nucleic Acid (LNA)-modified antisense oligonucleotides (gapmers) released from biomaterial scaffolds for specific and prolonged ADAMTS inhibition in co-delivered and resident chondrocytes, is an attractive therapeutic strategy. Here, a gapmer sequence identified from a gapmer screen showed 90% ADAMTS5 silencing in a monolayer culture of human OA chondrocytes. Incorporation of the gapmer in a fibrin-hyaluronic acid hydrogel exhibited a sustained release profile up to 14 days. Gapmers loaded in hydrogels were able to transfect both co-embedded chondrocytes and chondrocytes in a neighboring gapmer-free hydrogel, as demonstrated by flow cytometry and confocal microscopy. Efficient knockdown of ADAMTS5 was shown up to 14 days in both cell populations, i.e. the gapmer-loaded and gapmer-free hydrogel. This work demonstrates the use applicability of a hydrogel as a platform for combined local delivery of chondrocytes and an ADAMTS-targeting gapmer for catabolic gene modulation in OA.

Two independent proteomic approaches provide a comprehensive analysis of the synovial fluid proteome response to Autologous Chondrocyte Implantation

Background

Autologous chondrocyte implantation (ACI) has a failure rate of approximately 20%, but it is yet to be fully understood why. Biomarkers are needed that can pre-operatively predict in which patients it is likely to fail, so that alternative or individualised therapies can be offered. We previously used label-free quantitation (LF) with a dynamic range compression proteomic approach to assess the synovial fluid (SF) of ACI responders and non-responders. However, we were able to identify only a few differentially abundant proteins at baseline. In the present study, we built upon these previous findings by assessing higher-abundance proteins within this SF, providing a more global proteomic analysis on the basis of which more of the biology underlying ACI success or failure can be understood.

Methods

Isobaric tagging for relative and absolute quantitation (iTRAQ) proteomic analysis was used to assess SF from ACI responders (mean Lysholm improvement of 33; n = 14) and non-responders (mean Lysholm decrease of 14; n = 13) at the two stages of surgery (cartilage harvest and chondrocyte implantation). Differentially abundant proteins in iTRAQ and combined iTRAQ and LF datasets were investigated using pathway and network analyses.

Results

iTRAQ proteomic analysis confirmed our previous finding that there is a marked proteomic shift in response to cartilage harvest (70 and 54 proteins demonstrating ≥ 2.0-fold change and p < 0.05 between stages I and II in responders and non-responders, respectively). Further, it highlighted 28 proteins that were differentially abundant between responders and non-responders to ACI, which were not found in the LF study, 16 of which were altered at baseline. The differential expression of two proteins (complement C1s subcomponent and matrix metalloproteinase 3) was confirmed biochemically. Combination of the iTRAQ and LF proteomic datasets generated in-depth SF proteome information that was used to generate interactome networks representing ACI success or failure. Functional pathways that are dysregulated in ACI non-responders were identified, including acute-phase response signalling.

Conclusions

Several candidate biomarkers for baseline prediction of ACI outcome were identified. A holistic overview of the SF proteome in responders and non-responders to ACI  has been profiled, providing a better understanding of the biological pathways underlying clinical outcome, particularly the differential response to cartilage harvest in non-responders.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1573-4) contains supplementary material, which is available to authorized users.

Autologous chondrocyte implantation-derived synovial fluids display distinct responder and non-responder proteomic profiles

Background

Autologous chondrocyte implantation (ACI) can be used in the treatment of focal cartilage injuries to prevent the onset of osteoarthritis (OA). However, we are yet to understand fully why some individuals do not respond well to this intervention. Identification of a reliable and accurate biomarker panel that can predict which patients are likely to respond well to ACI is needed in order to assign the patient to the most appropriate therapy. This study aimed to compare the baseline and mid-treatment proteomic profiles of synovial fluids (SFs) obtained from responders and non-responders to ACI.

Methods

SFs were derived from 14 ACI responders (mean Lysholm improvement of 33 (17–54)) and 13 non-responders (mean Lysholm decrease of 14 (4–46)) at the two stages of surgery (cartilage harvest and chondrocyte implantation). Label-free proteome profiling of dynamically compressed SFs was used to identify predictive markers of ACI success or failure and to investigate the biological pathways involved in the clinical response to ACI.

Results

Only 1 protein displayed a ≥2.0-fold differential abundance in the preclinical SF of ACI responders versus non-responders. However, there is a marked difference between these two groups with regard to their proteome shift in response to cartilage harvest, with 24 and 92 proteins showing ≥2.0-fold differential abundance between Stages I and II in responders and non-responders, respectively. Proteomic data has been uploaded to ProteomeXchange (identifier: PXD005220). We have validated two biologically relevant protein changes associated with this response, demonstrating that matrix metalloproteinase 1 was prominently elevated and S100 calcium binding protein A13 was reduced in response to cartilage harvest in non-responders.

Conclusions

The differential proteomic response to cartilage harvest noted in responders versus non-responders is completely novel. Our analyses suggest several pathways which appear to be altered in non-responders that are worthy of further investigation to elucidate the mechanisms of ACI failure. These protein changes highlight many putative biomarkers that may have potential for prediction of ACI treatment success.

Efficacy and safety of autologous cell therapies for knee cartilage defects (autologous stem cells, chondrocytes or the two): randomized controlled trial design

AIM

The main aim of this trial is to test the safety and efficacy of autologous stromal/stem cells, chondrocytes or the two combined in the treatment of knee cartilage defects.

PATIENTS & METHODS

Patients with symptomatic chondral/osteochondral defects will be randomized to cell therapy treatment with one of three cell populations (1:1:1). The primary efficacy outcome is a functional knee score (Lysholm) at 15 months post-treatment and the primary safety outcome is the incidence of adverse events. Secondary objectives are to analyze repair tissues, quality of life and cost-utility assessments. Exploratory objectives are to identify predictors for success/potency and dose-response relationships.

RESULTS & CONCLUSION

This trial has been carefully designed so that valuable scientific and clinical information can be gathered throughout and in the final analysis.