Delivery of Agents Into Articular Cartilage With Electric Spark-Induced Sound Waves

: Perez AG, Nieminen HJ, Finnila M, Salmi A, Pritzker KPH, Lampsijarvi E, Paulin T, Airaksinen AJ, Saarakkala S, Haeggstrom E

Publisher: FRONTIERS MEDIA SA

: 2018

: Frontiers in Physics

: FRONTIERS IN PHYSICS

: FRONT PHYS

: ARTN 116

: 6

: 7

: 2296-424X

DOI: https://doi.org/10.3389/fphy.2018.00116

Localized delivery of drugs into articular cartilage (AC) may facilitate the development of novel therapies to treat osteoarthritis (OA). We investigated the potential of spark-gap-generated sound to deliver a drug surrogate, i.e., methylene blue (MB), into AC. In vitro experiments exposed bovine AC samples to either simultaneous sonication and immersion in MB (Treatment 1; n = 10), immersion in MB after sonication (Control 1; n = 10), solely immersion in MB (Control 2; n = 10), or neither sonication nor immersion in MB (Control 3; n = 10). The sonication protocol consisted of 1,000 spark-gap -generated pulses. Delivery of MB into AC was estimated from optical absorbance in transmission light microscopy. Optical absorbance was significantly greater in the treatment group up to 900 mu m depth from AC surface as compared to all controls. Field emission scanning electron microscopy (FESEM), histological analysis, and digital densitometry (DD) of sonicated (n = 6) and non-sonicated (n = 6) samples showed no evidence of sonication-induced changes in proteoglycan content or collagen structure. Consequently, spark-gap -generated sound may offer a solution for localized drug delivery into AC in a non-destructive fashion. Further research on this method may contribute to OA drug therapies.