The presence of extracellular matrix degrading metalloproteinases during fetal development of the intervertebral disc

Matrix metalloproteinases (MMPs) regulate connective tissue architecture and cell migration through extracellular matrix (ECM) degradation and are associated with both physiological and pathological processes. Although they are known to play a role in skeletal development, little is known about the role of MMPs in intervertebral disc (IVD) development. Sixteen fetal human lumbar spine segments, obtained at autopsy, were compared with five normal, non-fetal L4–L5 IVDs. Intensity and/or localization of immunohistochemical staining for MMP-1, -2, -3 and -14 were evaluated by three independent observers. MMP-2 production and activation was quantified by gelatin zymography. MMP-1 and -14 were abundantly present in the nucleus pulposus (NP) and notochordal (NC) cells of the fetal IVDs. In non-fetal IVDs, MMP-1 and -14 staining was significantly less intense (p = 0.001 and p < 0.001, respectively). MMP-3 was found in almost the entire IVD with no significant difference from non-fetal IVDs. MMP-2 staining in the NC and NP cells of the fetal IVD was moderate, but weak in the non-fetal IVD. Gelatin zymography showed a negative correlation of age with MMP-2 activity (p < 0.001). MMP-14 immunostaining correlated positively with MMP-2 activity (p = 0.001). For the first time, the presence of MMP-1, -2, -3 and -14 in the fetal human IVD is shown and the high levels of MMP-1, -2 and -14 suggest a role in the development of the IVD. In particular, the gradual decrease in MMP-2 activation during gestation pinpoints this enzyme as key player in fetal development, possibly through activation by MMP-1 and -14

Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique

Calcium phosphate ceramics, commonly applied as bone graft substitutes, are a natural choice of scaffolding material for bone tissue engineering. Evidence shows that the chemical composition, macroporosity and microporosity of these ceramics influences their behavior as bone graft substitutes and bone tissue engineering scaffolds but little has been done to optimize these parameters. One method of optimization is to place focus on a particular parameter by normalizing the influence, as much as possible, of confounding parameters. This is difficult to accomplish with traditional fabrication techniques. In this study we describe a design based rapid prototyping method of manufacturing scaffolds with virtually identical macroporous architectures from different calcium phosphate ceramic compositions. Beta-tricalcium phosphate, hydroxyapatite (at two sintering temperatures) and biphasic calcium phosphate scaffolds were manufactured. The macro- and micro-architectures of the scaffolds were characterized as well as the influence of the manufacturing method on the chemistries of the calcium phosphate compositions. The structural characteristics of the resulting scaffolds were remarkably similar. The manufacturing process had little influence on the composition of the materials except for the consistent but small addition of, or increase in, a beta-tricalcium phosphate phase. Among other applications, scaffolds produced by the method described provide a means of examining the influence of different calcium phosphate compositions while confidently excluding the influence of the macroporous structure of the scaffolds

Increased MMP-2 activity during intervertebral disc degeneration is correlated to MMP-14 levels

Intervertebral disc (IVD) degeneration is associated with the increased expression of several matrix metalloproteinases (MMPs), in particular MMP-2. However, little is known about the actual activity of MMP-2 in healthy and degenerated discs, or what mechanisms are involved in its activation. A major activation pathway involves complex formation with MMP-14 and a tissue inhibitor of metalloproteinases-2 (TIMP-2). In a series of 56 human IVDs, obtained at autopsy and graded according to the Thompson score (I-V), we analysed whether MMP-2 activity was increased in different stages of IVD degeneration and to what extent activation was related to the production of MMP-14 and TIMP-2. MMP-2 activation and production were quantified by gelatin zymography. Immunohistochemical staining of MMP-14 and TIMP-2 was quantified with a video overlay-based system. A positive correlation was observed between the amount of active MMP-2 and pro-MMP-2 and degeneration grade (p <0.001, correlation coefficient (CC) 0.557; and p <0.001, CC 0.556, respectively). MMP-2 activity correlated positively with MMP-14 and less strongly with TIMP-2 (P = 0.001, CC 0.436; and p = 0.03, CC 0.288, respectively). Moreover, immunopositivity for MMP-14 correlated to degeneration grade (p = 0.002, CC 0.398). IVD degeneration was associated with the activity of MMP-2 and the correlation of its activation with MMP-14 production suggests MMP-14 activates MMP-2 during degeneration. As MMP-14 is capable of activating several other enzymes that are also thought to be involved in IVD degeneration, it may be a key mediator of the degenerative process. Copyright (c) 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd

Can Ilizarov joint distraction delay the need for an arthrodesis of the ankle? A preliminary report

We applied joint distraction using an Ilizarov apparatus in 11 patients with post-traumatic osteoarthritis of the ankle to try to delay the need for an arthrodesis. Distraction for three months resulted in clinical improvement in pain and mobility for a mean of two years, with an increase in the joint space. We considered that these effects may be produced by the absence of mechanical stress on the cartilage combined with the intra-articular hydrostatic pressures during distraction. We measured these pressures during walking with distraction, and found levels very similar to those reported to improve osteoarthritic cartilage when applied in vitr

Joint distraction in treatment of osteoarthritis (II): effects on cartilage in a canine model

From a clinical point of view, joint distraction as a treatment for osteoarthritis (OA) of hip and ankle has been demonstrated to be very promising. Pain, joint mobility and functional ability, the most important factors for a patient with severe OA, all improved. Although radiographic joint space enlargement in a significant number of patients suggested cartilage repair, actual cartilage repair remains difficult to evaluate. Therefore the present study was initiated to evaluate the actual effects of joint distraction on cartilage. For this purpose a canine model for OA, anterior cruciate ligament transection (ACLT) was used. Sixteen weeks after ACLT articulating Ilizarov joint distraction of the knee was carried out. Absence of mechanical contact between articular surfaces and presence of intra-articular intermittent fluid pressure, characteristics of Ilizarov joint distraction, were confirmed. Twenty-five weeks after ACLT joint tissue of the dogs was analyzed. Biochemical analysis showed that after joint distraction the abnormal cartilage proteoglycan (PG) metabolism, characteristic for OA, had changed to a level found in control joints. Moreover, a mild degree of inflammation, present after ACLT, was reduced upon joint distraction. PG-content and histological cartilage degeneration had not (yet) improved within the time of treatment. Results suggest that the promising clinical results of Ilizarov joint distraction in patients with OA are accompanied by changes in cartilage metabolism. A change in proteoglycan turnover, indicating normalization of overall chondrocyte function, might in the long term, with normal joint use, lead to actual repair of cartilag