No abstract

Joint trauma results in the production of inflammatory cytokines that stimulate the secretion of catabolic enzymes, which degrade articular cartilage. Molecular fragments of the degraded articular cartilage further stimulate inflammatory cytokine production, with this process eventually resulting in post-traumatic osteoarthritis (PTOA). The loss of matrix component aggrecan occurs early in the progression of PTOA and results in the loss of compressive stiffness in articular cartilage. Aggrecan is highly sulfated, associates with hyaluronic acid (HA), and supports the compressive stiffness in cartilage. Presented here, we conjugated the HA-binding peptide GAHWQFNALTVRGSG (GAH) to anionic nanoparticles (hNPs). Nanoparticles conjugated with roughly 19 GAH peptides, termed 19 GAH-hNP, bound to HA in solution and increased the dynamic viscosity by 94.1% compared to an HA solution treated with unconjugated hNPs. Moreover, treating aggrecan-depleted (AD) cartilage explants with 0.10 mg of 19 GAH-hNP restored the cartilage compressive stiffness to healthy levels six days after a single nanoparticle treatment. Treatment of AD cartilage with 0.10 mg of 19 GAH-hNP inhibited the degradation of articular cartilage. Treated AD cartilage had 409% more collagen type II and 598% more GAG content than untreated-AD explants. The 19 GAH-hNP therapeutic slowed ECM degradation in AD cartilage explants, restored the compressive stiffness of damaged cartilage, and showed promise as a localized treatment for PTOA.

IMPACT: Our research would be the first therapeutic to both prevent and treat osteoarthritis - helping 27 millions U.S. citizens alone immediately. OBJECTIVES/GOALS: Our objective is to conjugate hyaluronic acid binding peptides (HABP) to anionic hollow nanoparticle (hNP), and allowing the HABP-hNP complex to penetrate into osteoarthritic cartilage, bind to exposed HA, prevent further degradation, and restore the compressive strength of articular cartilage. METHODS/STUDY POPULATION: N-isopropyl acrylamide, 2-acrylamindo-2-methyl-1-propanesulfonic acid, N,N’-bis(acryoyl)cystamine, and Acrylic Acid, in fluorescent batches rhodamine b isothiocyanate (RBITC), were polymerized via precipitation reaction. HA binding peptide, GAHWQFNALTVRGSG-Hydrazide (GAH-Hyd), was covalently bonded to the hNP using DMTMM chemistry. The reaction was halted by diluting the solution 10:1 with milliQ water and purified using tangential flow filtration. The dynamic viscosity of the six treatments were analyzed in a 70 kDa HA. Using a rheometer (Discovery HR-3) with a 20 mm parallel plate geometry, TA Instruments, New Castle, DE), a frequency sweep (0.01 -1000 Hz, 2.512 Pa) was conducted to measure the storage modulus of each solution. RESULTS/ANTICIPATED RESULTS: GAH-Hyd was successfully conjugated to the surface of the hNP and zeta-potential shows a significant increase in surface charge from -21.41 mV for unconjugated hNP to -8.94 mV for 65 GAH conjugated hNP, confirming conjugation. The hNPs need 65 ±10 GAH per nanoparticle to significantly bind to HA, shown by increasing the dynamic viscosity of the solution. The minimum concentration of 65 GAH-hNP required to significantly bind to HA is 313 µM. These data from our study display the ability to functionalized the surface of polymeric hNPs with site specific peptides and their ability to bind to diseased tissue. We expect the GAH-hNP system will restore the compressive strength of OA cartilage and prevent further HA degradation in ex vivo aggrecan depleted cartilage plugs. DISCUSSION/SIGNIFICANCE OF FINDINGS: Binding to exposed HA within the ECM of cartilage protects the HA from further degradation, halting the progression of OA. 65 GAH-hNP binds to HA at a 313 µM. Our system can be translated and used to treat a multitude of conditions by conjugating tissue specific peptides to the surface of our hNPs and delivery site specific therapeutics to diseases tissue.

OBJECTIVES/GOALS: Knocking down the inflammatory response following joint trauma may halt the cytokine cascade and prevent the resulting cyclic degradation of articular cartilage. MK2 inhibiting (MK2i) peptides are an emerging and promising class of pharmaceutical to treat post-traumatic osteoarthritis (PTOA); however, these peptides are susceptible to proteolytic degradation in the extracellular space. Our objective is to encapsulate MK2i in thermoresponsive hollow nanoparticles (hNPs) to knockdown the inflammatory cytokine IL-6 to prevent the cyclic degradation of articular cartilage. METHODS/STUDY POPULATION: NP Synthesis: N-isopropyl acrylamide (NIPAm) cores was initiated by potassium persulfate (KPS) in aqueous solution with sodium dodecylsulfate (SDS) at 70°C under a nitrogen for 2 hours. Then exposed to oxygen for 45 min, followed by a nitrogen purge. NIPAm, 2-acrylamindo-2-methyl-1-propanesulfonic acid (AMPS), N,N’-bis(acryoyl)cystamine (BAC), and Acrylic Acid (AAc), in fluorescent batches rhodamine b isothiocyanate (RBITC), were polymerized around the core to form the shell. NPs were purified using tangential flow filtration. The NPs were dialyzed at 4°C for 14 days to remove the core and form hNPs. Loading & Release: hNPs and MK2i were incubated at 1 mg/ml at 4°C for 24 h. MK2i released into 1x PBS and analyzed on HPLC. IL-6 Expression: Bovine chondrocytes seeded at 10,000 cell/cm2 were stimulated with 20 ng/ml IL-1b daily and treated once with 100 µg/ml MK2i loaded-NP or 100 µg/ml free MK2i treatment on day 2. Analyzed on bovine IL-6 ELISA. In Vivo Intra Articular Injections: 75 µl of 2 mg/ml hNPsRHB or a PBS control was injected into the right knee of 4-month old Fischer 344 (Envigo) rats. Rats were imaged daily for 7 days then euthanized, legs dissected, and imaged. RESULTS/ANTICIPATED RESULTS: Core removal facilitated increased MK2i release from hNPs, Fig 1A, allowing up to 63% after 5 days in PBS. The hNPs generated here offer a continual sustained release of MK2i and hNPs are non-cytotoxic (data not shown) up to 12 mg/ml. MK2i loaded-NPs significantly knocked down IL-6 production after a single treatment after 2 days, Figure 1B, and continued knockdown for up to 4 days. hNPsRBITC was successfully injected into rat joint space and was retained for at least 7-days compared to pre-injection and PBS control, Fig 1 B-C. DISCUSSION/SIGNIFICANCE OF IMPACT: hNPs protect MK2i from ECM degradation and offer continual sustained release into chondrocytes. Core removal allows for MK2i release in vitro with further sustained release compared to previous non-degradable model. The single MK2i treatment lead to a significant IL-6 knockdown bovine chondrocytes for up to 4 days in hNPs. We were able to successfully inject and retain fluorescently labeled hNPs within rat knees for 7 days. Our translational therapeutic shows the promise of delivering a degradable, non-cytotoxic hNP into the joint space to knockdown the inflammatory response to halt the cyclic progression of articular cartilage degradation and progression of PTOA. CONFLICT OF INTEREST DESCRIPTION: The authors declare the following competing financial interest(s): Moerae Matrix, Inc. has a worldwide exclusive license to the CPP (MK2 inhibitor peptide). A. Panitch owns greater than 5% of Moerae Matrix, Inc.