Periodic Reporting for period 1 - MEPHOS (Shaping the Mechano-Pharmacological properties of Microparticles and Extracellular Vesicles for the Treatment of Osteoarthritis)
Reporting period: 2020-04-01 to 2023-03-31
The MEPHOS team is designing, developing, and testing novel therapeutic strategies, drug delivery systems, and nanomedicines for the treatment and management of osteoarthritis (OA).
Osteoarthritis (OA) is a chronic disease caused by the progressive degeneration of the articular cartilage and subchondral bone and is associated with extensive synovial inflammation. It most commonly affects the joints of the knees, hands, feet, and spine and is also observed in shoulder and hip joints. The MEPHOS project focuses on the knee OA, where mechanical loading and interfacial lubrication play a major role, but the proposed approach and anticipated results could be applied to other joints as well as other diseases with similar manifestations. OA is not a disease of the sole cartilage but it rather affects the whole joint and its three major biological compartments (Figure 1): the articular cartilage; the synovium; and the synovial fluid. A healthy articular cartilage is composed of a highly porous matrix within which a few specialized cells – chondrocytes – reside (top inset in Figure 1). The porosity of cartilage and its water content are crucial in modulating the lubrication and load bearing capacity of the joint. Under pathological conditions, the presence of inflammatory factors negatively affect the function and viability of chondrocytes resulting in stiffer cells, reduced secretion of HA and other components of the extracellular matrix. This dictates the progressive degeneration of the cartilaginous tissue with a consequent reduction in its viscoelastic properties and overall mechanical support. A healthy synovium appears as a regular tissue populated by different cells, mostly synoviocytes and macrophages, and is properly nurtured by blood vessels and lymphatics (left inset in Figure 1). Macrophages, as sentinels of the immune system, line the interface between the tissue and the synovial fluid. Under pathological conditions, activated macrophages release inflammatory factors with the intent to recall locally additional macrophages. However, at the same time, these factors are toxic to chondrocytes and synoviocytes and affect their ability to deposit full length natural fibers, as HA, lubricin and others. Moreover, this inflammatory state makes the synovium hyperpermeable facilitating the clearance of molecules, fibers, and cells. Finally, the healthy synovial fluid is an ultrafiltrate of blood enriched with high molecular weight HA fibers, lubricin and phospholipids that are produced by synoviocytes and chondrocytes. Within this viscoelastic, non-Newtonian fluid, the most abundant HA establishes a complex, dynamic network of fibers and proteins via the creation of multiple weak, reversible bonds (right inset in Figure 1). Notably, a healthy knee can tolerate local pressures above 20 MPa while operating with friction coefficients as low as 0.001. However, under pathological conditions, the synovial fluid is progressively deprived of its precious fibers and molecules because of the higher clearance rates through the hyperpermeable synovium and lower secretion rates by inflamed synoviocytes and chondrocytes. This invariably results in higher interfacial friction and mechanical stresses that damage further the cartilage, exacerbate the synovial inflammation, harm synoviocytes and chondrocytes continuously feeding the vicious cycle and perpetuating the disease. The cross-talking among macrophages, synoviocytes and chondrocytes is key in regulating OA progression.
Across the EU, over 40 million people suffer of OA. Similar numbers are documented for the US. Indeed, in developed countries, OA is the single most common cause of disability and reduced mobility. As it results from ageing, obesity, excessive exercise (sport trauma), genetic predisposition, occupational injury, the number of adults with OA is projected to double by 2040. The economic impact of OA on the National Healthcare Systems and Employment Policies is enormous. In the US, from 2013 to 2015, adults with OA reported almost 200 million total lost workdays, which constituted 34% of reported lost workdays for any medical condition. In the EU, the average costs per-person vary from about 1.5k€ of Belgium to 2k€ for Italy and up to 10k€ in the Netherlands. Moreover, it is here important to recall that OA is associated with increased comorbidity due to limited mobility, whereby it has been estimated that 60% to 90% of adult patients have at least one other significant chronic condition, with the most common being cardiovascular disease, diabetes mellitus, hypertension and cancer.
Osteoarthritis (OA) is a chronic disease caused by the progressive degeneration of the articular cartilage and subchondral bone and is associated with extensive synovial inflammation. It most commonly affects the joints of the knees, hands, feet, and spine and is also observed in shoulder and hip joints. The MEPHOS project focuses on the knee OA, where mechanical loading and interfacial lubrication play a major role, but the proposed approach and anticipated results could be applied to other joints as well as other diseases with similar manifestations. OA is not a disease of the sole cartilage but it rather affects the whole joint and its three major biological compartments (Figure 1): the articular cartilage; the synovium; and the synovial fluid. A healthy articular cartilage is composed of a highly porous matrix within which a few specialized cells – chondrocytes – reside (top inset in Figure 1). The porosity of cartilage and its water content are crucial in modulating the lubrication and load bearing capacity of the joint. Under pathological conditions, the presence of inflammatory factors negatively affect the function and viability of chondrocytes resulting in stiffer cells, reduced secretion of HA and other components of the extracellular matrix. This dictates the progressive degeneration of the cartilaginous tissue with a consequent reduction in its viscoelastic properties and overall mechanical support. A healthy synovium appears as a regular tissue populated by different cells, mostly synoviocytes and macrophages, and is properly nurtured by blood vessels and lymphatics (left inset in Figure 1). Macrophages, as sentinels of the immune system, line the interface between the tissue and the synovial fluid. Under pathological conditions, activated macrophages release inflammatory factors with the intent to recall locally additional macrophages. However, at the same time, these factors are toxic to chondrocytes and synoviocytes and affect their ability to deposit full length natural fibers, as HA, lubricin and others. Moreover, this inflammatory state makes the synovium hyperpermeable facilitating the clearance of molecules, fibers, and cells. Finally, the healthy synovial fluid is an ultrafiltrate of blood enriched with high molecular weight HA fibers, lubricin and phospholipids that are produced by synoviocytes and chondrocytes. Within this viscoelastic, non-Newtonian fluid, the most abundant HA establishes a complex, dynamic network of fibers and proteins via the creation of multiple weak, reversible bonds (right inset in Figure 1). Notably, a healthy knee can tolerate local pressures above 20 MPa while operating with friction coefficients as low as 0.001. However, under pathological conditions, the synovial fluid is progressively deprived of its precious fibers and molecules because of the higher clearance rates through the hyperpermeable synovium and lower secretion rates by inflamed synoviocytes and chondrocytes. This invariably results in higher interfacial friction and mechanical stresses that damage further the cartilage, exacerbate the synovial inflammation, harm synoviocytes and chondrocytes continuously feeding the vicious cycle and perpetuating the disease. The cross-talking among macrophages, synoviocytes and chondrocytes is key in regulating OA progression.
Across the EU, over 40 million people suffer of OA. Similar numbers are documented for the US. Indeed, in developed countries, OA is the single most common cause of disability and reduced mobility. As it results from ageing, obesity, excessive exercise (sport trauma), genetic predisposition, occupational injury, the number of adults with OA is projected to double by 2040. The economic impact of OA on the National Healthcare Systems and Employment Policies is enormous. In the US, from 2013 to 2015, adults with OA reported almost 200 million total lost workdays, which constituted 34% of reported lost workdays for any medical condition. In the EU, the average costs per-person vary from about 1.5k€ of Belgium to 2k€ for Italy and up to 10k€ in the Netherlands. Moreover, it is here important to recall that OA is associated with increased comorbidity due to limited mobility, whereby it has been estimated that 60% to 90% of adult patients have at least one other significant chronic condition, with the most common being cardiovascular disease, diabetes mellitus, hypertension and cancer.
In this context, the MEPHOS team is developing injectable drug depots comprising shape-defined microparticles (μPL ). In the current configuration, the µPL appear as microparticles with a square base of 20×20 μm and a height ranging from 5 to 10 and 20 μm (Figure 2A). μPL have been realized in polylactic-co-glycolic acid (PLGA) and other synthetic and natural polymers, which are well established materials for biomedical applications and are already approved for in human use. μPL have been designed to deliver a broad range of therapeutic payloads, including anti-inflammatory drugs such as dexamethasone (DEX) (Figure 1B); small inhibitors of the CCR2 receptor, such as the molecule RS504393 (Figure 1C); and polymeric nanoparticles for the intracellular deposition of siRNA against metallo-proteinases (Figure 1D). These microparticles exhibit distinct physico-chemical properties, dictated by their size and shape and composition, which can be simultaneously and independently tailored during the synthesis process. Size and shape control provide desirable formulation homogeneity and reproducibility, while ability to tune particle mechanical properties can be used to achieve optimal, application-specific properties.
The shape-defined microparticles (μPL) developed by the MEPHOS team have already demonstrated superior anti-inflammatory properties as compared to the currently approved drugs. Specifically, one single intra-articular injection of dexamethasone-loaded microPLates (DEX-μPL) reduces the concentration of pro-inflammatory cytokines with respect to the untreated control at least up to 1 month. Similar sustained effect is observed with the intra-articular deposition of CCR2 inhibitors and anti-MMP13-siRNA nanoparticles. In the latter two cases, partial cartilage regeneration has been favored while bone remodeling has been mitigated. Overall, one single injection of μPL loaded with different therapeutic agents can ameliorate the overall joint health for at least 1 month. A longer therapeutic effect is expected for the second generation of μPL that will be realized with different materials and loaded with more potent therapeutic agents.