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.

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.