Nanomechanical Properties of Articular Cartilage Due to the PRP Injection in Experimental Osteoarthritis in Rabbits.

The purpose of this study was twofold. Firstly, we proposed a measurement protocol for the atomic force microscopy (AFM) method to determine the nanomechanical properties of articular cartilage in experimental osteoarthritis in rabbits. Then, we verified if mechanical properties can be evaluated with AFM shortly after platelet-rich plasma (PRP) injection. We hypothesized that the modulus determined by AFM indentation experiments could be utilized as a progressive disease marker during the treatment of osteoarthritis. The rabbits were equally divided into three groups of six: control (group 1); injections of saline (0.5 mL) and 10% surgical talc (Talcum Pharmaceutical®, Minsk, Belarus) were delivered into the right knee under the patella (group 2 and 3); and PRP was injected into the right knee (group 3). In group 2, the arithmetic average of absolute values (Ra) change was a 25% increase; the maximum peak height (Rp) increased by over 102%, while the mean spacing between local peaks (S) increased by 28% (p < 0.05). In group 3, Ra increased by 14% and Rp increased by 32%, while S decreased by 75% (p < 0.05). The Young's modulus of the surface layers decreased by 18% as a result of induced model of osteoarthritis (IMO) (p < 0.05), and it increased by 9% (p < 0.05) as a result of PRP therapy, which means that the mechanical properties of cartilage were partially recovered. This research demonstrates that Young's modulus utilized on a nanometer scale has potential to be a progressive disease marker during the treatment of osteoarthritis.

Biophysical Stimuli: A Review of Electrical and Mechanical Stimulation in Hyaline Cartilage.

OBJECTIVE: Hyaline cartilage degenerative pathologies induce morphologic and biomechanical changes resulting in cartilage tissue damage. In pursuit of therapeutic options, electrical and mechanical stimulation have been proposed for improving tissue engineering approaches for cartilage repair. The purpose of this review was to highlight the effect of electrical stimulation and mechanical stimuli in chondrocyte behavior. DESIGN: Different information sources and the MEDLINE database were systematically revised to summarize the different contributions for the past 40 years. RESULTS: It has been shown that electric stimulation may increase cell proliferation and stimulate the synthesis of molecules associated with the extracellular matrix of the articular cartilage, such as collagen type II, aggrecan and glycosaminoglycans, while mechanical loads trigger anabolic and catabolic responses in chondrocytes. CONCLUSION: The biophysical stimuli can increase cell proliferation and stimulate molecules associated with hyaline cartilage extracellular matrix maintenance.

[Shoulder cartilage regeneration : Indications, possibilities, surgical implementation]. / Knorpelreparative Eingriffe am Schultergelenk : Indikationen, Möglichkeiten, operative Durchführung.

Asymptomatic cartilage lesions of the shoulder are frequent. Symptomatic lesions are treated analogously to other hyaline cartilage bearing joints and can be treated arthroscopically in the vast majority of cases. The therapeutic options can be subdivided into resection, stimulation and transplantation of the defect cartilage. There are only a few reports about outcome after cartilage restoration surgery in the literature, and microfracturing is the surgical technique that has been most investigated.

Neocartilage integration in temporomandibular joint discs: physical and enzymatic methods.

Integration of engineered musculoskeletal tissues with adjacent native tissues presents a significant challenge to the field. Specifically, the avascularity and low cellularity of cartilage elicit the need for additional efforts in improving integration of neocartilage within native cartilage. Self-assembled neocartilage holds significant potential in replacing degenerated cartilage, though its stabilization and integration in native cartilage require further efforts. Physical and enzymatic stabilization methods were investigated in an in vitro model for temporomandibular joint (TMJ) disc degeneration. First, in phase 1, suture, glue and press-fit constructs were compared in TMJ disc intermediate zone defects. In phase 1, suturing enhanced interfacial shear stiffness and strength immediately; after four weeks, a 15-fold increase in stiffness and a ninefold increase in strength persisted over press-fit. Neither suture nor glue significantly altered neocartilage properties. In phase 2, the effects of the enzymatic stabilization regimen composed of lysyl oxidase, CuSO4 and hydroxylysine were investigated. A full factorial design was employed, carrying forward the best physical method from phase 1, suturing. Enzymatic stabilization significantly increased interfacial shear stiffness after eight weeks. Combined enzymatic stabilization and suturing led to a fourfold increase in shear stiffness and threefold increase in strength over press-fit. Histological analysis confirmed the presence of a collagen-rich interface. Enzymatic treatment additionally enhanced neocartilage mechanical properties, yielding a tensile modulus over 6 MPa and compressive instantaneous modulus over 1200 kPa at eight weeks. Suturing enhances stabilization of neocartilage, and enzymatic treatment enhances functional properties and integration of neocartilage in the TMJ disc. Methods developed here are applicable to other orthopaedic soft tissues, including knee meniscus and hyaline articular cartilage.

Significance of cartilage endplate within herniated disc tissue.

PURPOSE: Disc herniations sometimes contain hyaline cartilage fragments, but their origins and significance are uncertain. METHODS: Herniations were removed surgically from 21 patients (aged 35-74 years) whose main symptom was sciatica (10 patients) or back pain (11 patients). Frozen sections, 5 µm thick, were examined histologically, and antibodies were used to label the matrix-degrading enzyme MMP 1, pro-inflammatory mediator TNFα, and cell proliferation marker Ki-67. Proportions of each tissue type were quantified by image analysis. Cartilage and bone components of the endplate were examined in 7-µm frozen sections from 16 cadaveric spines, aged 61-98 years. RESULTS: Cartilage fragments were found in 10/21 herniations. They averaged 5.0 mm in length, comprised 25 % of the herniation area, and two had some bone attached. Hyaline cartilage was more common in herniations from patients with sciatica (7/10) than with back pain (3/11, P = 0.050), and the area (%) of the herniation occupied by the cartilage was greater in sciatica patients (P < 0.05). Cartilage fragments showed little evidence of swelling, proteoglycan loss or inflammatory cell invasion, although cell clustering was common, and TNFα was sometimes expressed. Each cartilage fragment showed at least one straight edge, as if it had been peeled off the bony endplate, and this mechanism of failure was demonstrated in preliminary mechanical experiments. CONCLUSION: Disc herniations often include hyaline cartilage pulled from the vertebral endplates. Cartilage fragments show little swelling or proteoglycan loss, and may be slow to resorb, increasing the risk of persisting sciatica. Loss of cartilage will increase endplate permeability, facilitating endplate inflammation and disc infection.

Intra-articular administration of hyaluronic acid increases the volume of the hyaline cartilage regenerated in a large osteochondral defect by implantation of a double-network gel.

Implantation of PAMPS/PDMAAm double-network (DN) gel can induce hyaline cartilage regeneration in the osteochondral defect. However, it is a problem that the volume of the regenerated cartilage tissue is gradually reduced at 12 weeks. This study investigated whether intra-articular administration of hyaluronic acid (HA) increases the volume of the cartilage regenerated with the DN gel at 12 weeks. A total of 48 rabbits were used in this study. A cylindrical osteochondral defect created in the bilateral femoral trochlea was treated with DN gel (Group DN) or left without any implantation (Group C). In both Groups, we injected 1.0 mL of HA in the left knee, and 1.0 mL of saline solution in the right knee. Quantitative histological evaluations were performed at 2, 4, and 12 weeks, and PCR analysis was performed at 2 and 4 weeks after surgery. In Group DN, the proteoglycan-rich area was significantly greater in the HA-injected knees than in the saline-injected knees at 12 weeks (P = 0.0247), and expression of type 2 collagen, aggrecan, and Sox9 mRNAs was significantly greater in the HA-injected knees than in the saline-injected knees at 2 weeks (P = 0.0475, P = 0.0257, P = 0.0222, respectively). The intra-articular administration of HA significantly enhanced these gene expression at 2 weeks and significantly increased the volume of the hyaline cartilage regenerated by implantation of a DN gel at 12 weeks. This information is important to develop an additional method to increase the volume of the hyaline cartilage tissue in a potential cartilage regeneration strategy using the DN gel.

Cartilage as a target of autoimmunity: a thin layer.

The articular cartilage is an important component of human organism that has elasticity, low-friction surface, and ability to withstand great physical forces. The structure consists of collagens and proteoglycans, whereas non-collagenous proteins are needed for the organization and modulation of the molecular networks. The structural elements of the cartilage are typical to that tissue and could, in part, account for the localization of the inflammatory response to the joint. For this reason cartilage is of particular interest in autoimmunity as it may represent a source of antigens. It is well known that sensitization with collagens can produce autoimmune rheumatic diseases in experimental models. So far, the cartilage proteins that have been clearly characterized to be arthritogenic in experimental models involve types II and XI collagen, cartilage oligomeric matrix protein, and aggrecan. It is likely that these proteins are also recognized at different stages in the development of rheumatoid arthritis and in other autoimmune diseases. The mechanisms determining the trigger of a cartilage-specific immune response, its development and outcome are poorly understood. Most likely, the distribution and concentration of a specific cartilage protein may play a role by eliciting an autoimmune response. Indeed, the inflammatory processes lead to tissue damage mediated by the intervention of several factors such as autoantibodies, cytokines as well as cells of the innate an adaptive immunity. For this reason, even previously-considered degenerative diseases, such as osteoarthritis, should now be re-evaluated as at least partly inflammatory-driven. Thus, the objective of this review is to describe the clinical conditions sustained by the immune-mediated reactions to cartilage, which represents the target organ in a number of autoimmune diseases.

[The morphological characteristics of osteoarthrosis].

Osteoarthrosis (OA) is a group of overlapping diseases that have various etiologies, but equal biological, morphological, and clinical outcomes. OA is characterized by degenerative and destructive changes in the articular hyaline cartilage, subchondral bone, spongiosis, synovium, capsule, and articular ligamentous apparatus. The clinical symptoms of OA are closely associated with morphological changes in articular tissue elements, primarily in the articular hyaline cartilage. Six stages that reflect the magnitude of changes in the hyaline cartilage and 4 degrees of the extent of the process along the articular surface are identified.