1 Departments of Bioengineering and Mechanical Engineering, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
2 Centre for Biomedical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
3 Department of Orthopaedic Surgery, Beth Israel Deaconess Medical Centre (BIDMC), Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
4 Current affiliation: Rehabilitation Medicine Research Centre, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA
5 Department of Orthopaedic Surgery, Clínica Alemana de Santiago, Avenida Vitacura 5951, Vitacura, Chile
6 Departments of Biological, Mechanical and Electrical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
7 Current affiliation: Departments of Internal Medicine and Orthopaedic Surgery, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA
§ These authors equally contributed to this paper
Abstract
Disease-modifying osteoarthritis drugs (DMOADs) should reach their intra-tissue target sites at optimal doses for clinical efficacy. The dense, negatively charged matrix of cartilage poses a major hindrance to the transport of potential therapeutics. In this work, electrostatic interactions were utilised to overcome this challenge and enable higher uptake, full-thickness penetration and enhanced retention of dexamethasone (Dex) inside rabbit cartilage. This was accomplished by using the positively charged glycoprotein avidin as nanocarrier, conjugated to Dex by releasable linkers. Therapeutic effects of a single intra-articular injection of low dose avidin-Dex (0.5 mg Dex) were evaluated in rabbits 3 weeks after anterior cruciate ligament transection (ACLT). Immunostaining confirmed that avidin penetrated the full cartilage thickness and was retained for at least 3 weeks. Avidin-Dex suppressed injury-induced joint swelling and catabolic gene expression to a greater extent than free Dex. It also significantly improved the histological score of cell infiltration and morphogenesis within the periarticular synovium. Micro-computed tomography confirmed the reduced incidence and volume of osteophytes following avidin-Dex treatment. However, neither treatment restored the loss of cartilage stiffness following ACLT, suggesting the need for a combinational therapy with a pro-anabolic factor for enhancing matrix biosynthesis. The avidin dose used caused significant glycosaminoglycan (GAG) loss, suggesting the use of higher Dex : avidin ratios in future formulations, such that the delivered avidin dose could be much less than that shown to affect GAGs. This charge-based delivery system converted cartilage into a drug depot that could also be employed for delivery to nearby synovium, menisci and ligaments, enabling clinical translation of a variety of DMOADs.
Keywords
- Intra-cartilage drug delivery
- cartilage
- electrostatics
- dexamethasone
- post-traumatic osteoarthritis
- rabbit anterior cruciate ligament transection
- avidin
