How do visual, spectroscopic and biomechanical changes of cartilage correlate in osteoarthritic knee joints?

BACKGROUND: Characteristic changes in cartilage of human knee joints with different degrees of osteoarthritis (OA) have been investigated by visual, biophotonical and biomechanical examination. Knowledge about the cartilage composition and changes during the development of OA is important for diagnostic decisions and understanding the pathogenesis of OA. METHODS: Thirty two patients with severe knee OA received endoprosthetic replacement. During surgical intervention cartilage specimen were harvested from defined surface areas of the joints. The degree of cartilage defects was classified visually (ICRS Grade: International Cartilage Repair Society), biophotonically (NIRS: near infrared spectroscopy) and biomechanically (Young's Modulus). To characterise links between the investigated parameters the Spearman's rank correlation coefficient was used. FINDINGS: Significant negative correlations were found between visual macroscopic degree of degeneration (ICRS Grade) and biophotonic characteristics (NIRS) (rho=-0.467) or cartilage stiffness (Young's Modulus) (rho=-0.501). Between NIRS and Young's Modulus significant positive correlation of rho=0.535 was detected. INTERPRETATION: Visual, biophotonic and biomechanical properties of cartilage reveal strong correlations in all degrees of cartilage defects in patients with severe OA. According to these results, we indicate that an objective, non-invasive and non-destructive measurement of cartilage properties during open and arthroscopic knee surgery is possible by NIRS and provide a novel tool to evaluate disease intervention and treatment.

Detection and evaluation of initial cartilage pathology in man: A comparison between MRT, arthroscopy and near-infrared spectroscopy (NIR) in their relation to initial knee pain.

BACKGROUND AND AIMS: MRI and arthroscopy are important methods in the evaluation of cartilage pathology. But frequently initial changes of cartilage in combination with chronic knee pain cannot be detected by employing these two methods. Better diagnostic tools for the detection of the early stages of osteoarthritis (OA) are required. The objective of this study was to show that near-infrared spectroscopy (NIRS) can be incorporated into routine arthroscopy to improve detection and assessment of the initial cartilage pathology. Furthermore correlations between findings in MRI, arthroscopy and NIRS in patients with initial symptoms of OA have studied. METHODS: Patients (n=21, 12 women, 9 men, age: 15-59 years, mean 34.19 years) with knee pain lasting for at least half a year without any trauma of the knee in their history were interviewed (body weight, smoking behaviour) and clinically evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Also serum parameters (cholesterol, lipids) were analysed, conventional X-rays in three directions (evaluated according to Kellgren and Lawrence) and MRI (evaluation of cartilage damage according to the ICRS-score) were performed preoperatively in all patients. During subsequent arthroscopy cartilage damage was evaluated according to the ICRS-score. In addition the spectral reflection of cartilage was investigated in all knees using a special micro-glass-fiber probe in the near-infrared light region (spectral range between 1150 and 1475nm). To characterize relations between the investigated parameters the Spearman's rank correlation coefficient was used. Inter-observer variance was calculated employing the Cohens-Kappa-test. RESULTS: MRI demonstrated a strong inter-observer variance with no significant correlations to other parameters. The same was observed for arthroscopic findings. Only NIRS showed significant correlations with three out of five KOOS subscores. Within the general parameters only smoking behaviour showed a significant correlation with two of the KOOS-scores. NIRS therefore seemed to be a sensitive diagnostic tool in detection of initial pathology in human cartilage. The additional necessary time for the spectroscopic investigation as part of the routine arthroscopy ranged between 3 and 7min (mean: 4min 18s). CONCLUSION: Particularly for early-stage cartilage lesions (ICRS 0/I) MRI and arthroscopy have rather low predictive value. The inter-observer variance is very high (Cohens-Kappa<0.4). Correlations found between NIRS and KOOS suggest that NIRS potentially can be used for detection of initial cartilage pathology and may be helpful in the evaluation of the benefit of different medical or surgical interventions at early-stage of articular cartilage damage.

Advanced glycation end products induce cell cycle arrest and proinflammatory changes in osteoarthritic fibroblast-like synovial cells.

INTRODUCTION: Advanced glycation end products (AGEs) have been introduced to be involved in the pathogenesis of osteoarthritis (OA). The influence of AGEs on osteoarthritic fibroblast-like synovial cells (FLS) has been incompletely understood as yet. The present study investigates a potential influence of AGE-modified bovine serum albumin (AGE-BSA) on cell growth, and on the expression of proinflammatory and osteoclastogenic markers in cultured FLS. METHODS: FLS were established from OA joints and stimulated with AGE-BSA. The mRNA expression of p27Kip1, RAGE (receptor for AGEs), nuclear factor kappa B subunit p65 (NFkappaB p65), tumor necrosis factor alpha (TNF-alpha, interleukin-6 (IL-6), receptor activator of NFkappaB ligand (RANKL) and osteoprotegerin was measured by real-time PCR. The respective protein expression was evaluated by western blot analysis or ELISA. NFkappaB activation was investigated by luciferase assay and electrophoretic mobility shift assay (EMSA). Cell cycle analysis, cell proliferation and markers of necrosis and early apoptosis were assessed. The specificity of the response was tested in the presence of an anti-RAGE antibody. RESULTS: AGE-BSA was actively taken up into the cells as determined by immunohistochemistry and western blots. AGE-induced p27Kip1 mRNA and protein expression was associated with cell cycle arrest and an increase in necrotic, but not apoptotic cells. NFkappaB activation was confirmed by EMSAs including supershift experiments. Anti-RAGE antibodies attenuated all AGE-BSA induced responses. The increased expression of RAGE, IL-6 and TNF-alpha together with NFkappaB activation indicates AGE-mediated inflammation. The decreased expression of RANKL and osteoprotegerin may reflect a diminished osteoclastogenic potential. CONCLUSIONS: The present study demonstrates that AGEs modulate growth and expression of genes involved in the pathophysiological process of OA. This may lead to functional and structural impairment of the joints.

A primary culture technique of adult retina for regeneration studies on adult CNS neurons.

This protocol details a tissue culture technique that allows for quantified regeneration studies on adult retinal ganglion cells (RGCs), that is, CNS neurons. The method may also allow for elucidation of molecular cues, for example of signals relevant in neuronal survival and axon regeneration. The procedure relies on fractioned stripe culture of previously injured retina in defined culture media. Naive dendritic cell contacts of RGCs are preserved, and the system is independent of growth factors. In contrast to other techniques, the protocol is based on tissue grown from adult animals; it dispenses immature co-cultures and evaluates the outgrowth of unmyelinated neurites in a milieu lacking CNS myelin. The technique is suitable for rodent retina from mouse or rat. A growth-conditioning injury of the optic nerve is set 10 days before retinal explantation. Explants are cultured for 5-7 days. Mere preparation of a single retina should be completed within 20 min.

Erythropoietin promotes regeneration of adult CNS neurons via Jak2/Stat3 and PI3K/AKT pathway activation.

The cytokine hormone erythropoietin (EPO) has proved neuroprotective in CNS injury, and clinical trials for ischemic stroke are ongoing. The capability of EPO to restore postmitotic CNS architecture and function by fibre regeneration has not been examined. Here, we compared in vitro outgrowth capacity of adult retinal ganglion cells (RGCs) following optic nerve (ON) lesion in the presence and absence of EPO. Immediate EPO conditioning in vivo, or delayed EPO treatment of cultures with 10--10,000 IU rhEPO significantly increased numbers (2.66-fold) and length (8.31-fold) of newly generated neurites, without evoking rheological complications. EPO induced Stat3 phosphorylation in RGCs, and inhibition of Jak2/Stat3 abolished EPO-induced growth. EPO-facilitated neuritogenesis was paralleled by upregulation of Bcl-X(L), a Bcl-2 homologue capable of promoting RGC regeneration. The PI3K/Akt pathway was also involved in antiapoptotic and regeneration-enhancing EPO actions. In conclusion, EPO treatment may offer a unique dual-function strategy for neuroprotection and regeneration.