[Histopathological examination of joint degeneration: typing, grading and staging of osteoarthritis]

Management of osteoarthritis: From drug molecules to nano/micromedicines

With the change in lifestyle and aging of the population, osteoarthritis (OA) is emerging as a major medical burden globally. OA is a chronic inflammatory and degenerative disease initially manifesting with joint pain and eventually leading to permanent disability. To date, there are no drugs available for the definitive treatment of osteoarthritis and most therapies have been palliative in nature by alleviating symptoms rather than curing the disease. This coupled with the vague understanding of the early symptoms and methods of diagnosis so that the disease continues as a global problem and calls for concerted research efforts. A cascade of events regulates the onset and progression of osteoarthritis starting with the production of proinflammatory cytokines, including interleukin (IL)‐1β, IL‐6, tumor necrosis factor (TNF)‐α; catabolic enzymes, such as matrix metalloproteinases (MMPs)‐1, ‐3, and ‐13, culminating into cartilage breakdown, loss of lubrication, pain, and inability to load the joint. Although intra‐articular injections of small and macromolecules are often prescribed to alleviate symptoms, low residence times within the synovial cavity severely impair their efficacy. This review will briefly describe the factors dictating the onset and progression of the disease, present the current clinically approved methods for its treatment and diagnosis, and finally elaborate on the main challenges and opportunities for the application of nano/micromedicines in the treatment of osteoarthritis. Thus, future treatment regimens will benefit from simultaneous consideration of the mechanobiological, the inflammatory, and tissue degradation aspects of the disease.

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement

Top-Down Fabricated microPlates for Prolonged, Intra-articular Matrix Metalloproteinase 13 siRNA Nanocarrier Delivery to Reduce Post-traumatic Osteoarthritis

Post-traumatic osteoarthritis (PTOA) associated with joint injury triggers a degenerative cycle of matrix destruction and inflammatory signaling, leading to pain and loss of function. Here, prolonged RNA interference (RNAi) of matrix metalloproteinase 13 (MMP13) is tested as a PTOA disease modifying therapy. MMP13 is upregulated in PTOA and degrades the key cartilage structural protein type II collagen. Short interfering RNA (siRNA) loaded nanoparticles (siNPs) were encapsulated in shape-defined poly(lactic-co-glycolic acid) (PLGA) based microPlates (μPLs) to formulate siNP-μPLs that maintained siNPs in the joint significantly longer than delivery of free siNPs. Treatment with siNP-μPLs against MMP13 (siMMP13-μPLs) in a mechanical load-induced mouse model of PTOA maintained potent (65-75%) MMP13 gene expression knockdown and reduced MMP13 protein production in joint tissues throughout a 28-day study. MMP13 silencing reduced PTOA articular cartilage degradation/fibrillation, meniscal deterioration, synovial hyperplasia, osteophytes, and pro-inflammatory gene expression, supporting the therapeutic potential of long-lasting siMMP13-μPL therapy for PTOA.

Synthesis of Two Methotrexate Prodrugs for Optimizing Drug Loading into Liposomes

Methotrexate (MTX), a compound originally used as an anticancer drug, has also found applications in a broad variety of autoimmune disorders thanks to its anti-inflammation and immunomodulatory functions. The broad application of MTX is anyway limited by its poor solubility in biological fluids, its poor bioavailability and its toxicity. In addition, encapsulating its original form in nanoformulation is very arduous due to its considerable hydrophobicity. In this work, two strategies to efficiently encapsulate MTX into liposomal particles are proposed to overcome the limitations mentioned above and to improve MTX bioavailability. MTX solubility was increased by conjugating the molecule to two different compounds: DSPE and PEG. These two compounds commonly enrich liposome formulations, and their encapsulation efficiency is very high. By using these two prodrugs (DSPE-MTX and PEG-MTX), we were able to generate liposomes comprising one or both of them and characterized their physiochemical features and their toxicity in primary macrophages. These formulations represent an initial step to the development of targeted liposomes or particles, which can be tailored for the specific application MTX is used for (cancer, autoimmune disease or others).

[Histopathological classification principles of rheumatic joint diseases : Contribution of pathology to the diagnosis]

Even though the diagnostics of rheumatic joint diseases are mostly based on clinical, immunoserological and imaging criteria, histopathology can also make a significant contribution. This is particularly true for clinically unclear monoarticular and periarticular diseases. The contribution of histopathology to the diagnosis of rheumatic diseases is manifold since the histopathological differential diagnosis includes the complete spectrum of synovial diseases. This heterogeneous pathogenetic spectrum is described in the joint pathology algorithm, which includes inflammatory and non-inflammatory diseases. To the latter group belong certain benign tumors such as the diffuse variant of the tenosynovial giant cell tumor, lipoma, hemangioma, vascular malformations and synovial chondromatosis. Additionally, the rare group of storage diseases should be kept in mind. Inflammatory diseases can be discriminated into crystal-induced arthropathies mainly such as gout and pseudogout, into granulomatous diseases such as tuberculosis and foreign-body inoculations, and finally into the large group of non-granulomatous, non-infectious synovitis. This large group is by far the most common, and it often causes difficulties in assigning the histopathological findings to a concrete rheumatologic diagnosis. In this context the synovitis score should be applied as a diagnostic device in these cases, leading to the diagnosis of a low-grade synovitis (which is associated with degenerative arthropathies) or of a high-grade synovitis (associated with rheumatic diseases). Identification of crystals and crystal-like deposits should be carried out with the application of the joint particle algorithm which addresses the identification of endogenous and non-endogenous particle deposits in the synovial tissues. Additionally, the synovitis-score may be used for evaluation of arthritis-progresssion and for the evaluation of inflammation-regression as a consequence of therapy with biologicals.

Experimental joint immobilization and remobilization in the rats

[Purpose] The purpose of our study was to clarify temporal effects on restrictions to range of motion and the histopathological changes of joint components after joint immobilization in a rat knee-contracture model. [Subjects] Fifty-four male Wistar rats were randomly divided into two groups: a fixation group, and a control group. [Methods] In the fixation group, unilateral knee joints were immobilized at full flexion using a plaster cast for 4 weeks. At four weeks the animals were randomly divided into six subgroups, corresponding to the time of examination after cast removal: 0, 4, 8, 16, 24, and 32 weeks. For comparison, control group animals of corresponding age were also examined. [Results] Although movement restrictions of the knee joint had completely recovered 6 weeks after the cast removal, cartilage and synovial membrane structures did not completely recover. [Conclusion] These findings have not previously been reported, and as they form an addition to the fundamental scientific foundations of physical therapy, further research must examine these findings from a variety of perspectives.

[Indications for tissue biopsy. Diagnostic histopathology in rheumatological diseases]

The role of a standardized histopathological examination of tissue biopsies and of different tissue compartments (synovia, vascular tissue, bone) is discussed in order to stratify the therapy of different forms of arthritis and other rheumatological diseases. Furthermore the diagnostic steps for the histopathological diagnosis of metabolic osteopathic diseases are highlighted. The synovitis-score is described as a diagnostic device leading to the diagnosis of a low-grade synovitis, which is associated with degenerative and posttraumatic arthropathies, or of a high-grade synovitis which is associated with rheumatic diseases.