A properly sized nanoparticle linked to a peptide that binds specifically to cartilage proved an effective drug delivery method when injected into the knees of mice. One of the most promising applications of near term nanotech is the ability to combine different chemical and biological functions to delivery drugs to the right places. Pete Mansell writes of another example at in-Pharma Technologist.com. Excerpts from “Targeted nanoparticles open up cartilage to drug delivery“:
A novel delivery system that converts the structure of cartilage “from a barrier into a reservoir” could provide an answer to the challenge of administering and maintaining drugs in avascular tissue.
Modified polymeric nanoparticles developed by researchers at the École Polytechnique Fédérale de Lausanne in Switzerland and the University of Massachusetts in the US were found in animal studies to accumulate in an extracellular matrix (ECM) of articular cartridge at concentrations of up to 72 times more than non-targeted nanoparticles, remaining in the matrix without statistically significant clearance for up to 96 hours.
As Jeffrey Hubbell et al point out in a paper published in Nature Materials, delivering drugs to cartilage for purposes such as treating early degradation in osteoarthritis is usually hampered by poor bioavailability due to the lack of vascularised tissue and the dense ECM, which acts as a barrier to entry.
The avascularity of cartilage tissue favours regional administration of the drug within the joint space rather than into the systemic circulation. However, compounds are rapidly cleared from the synovial fluid into the lymphatic system, accounting for the low bioavailability and raising the possibility of adverse systemic effects.
The researchers sought to overcome these obstacles by developing particles that would be small enough to enter the cartilage matrix, as it is dynamically compressed during normal movement, and would display sufficient affinity for a cartilage ECM component to be retained there.
The research was published in Nature Materials (abstract)