AUTHOR=García Pérez Alejandro , Nieminen Heikki J. , Finnilä Mikko , Salmi Ari , Pritzker Kenneth P. H. , Lampsijärvi Eetu , Paulin Tor , Airaksinen Anu J. , Saarakkala Simo , Hæggström Edward 

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

JOURNAL=Frontiers in Physics

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2018.00116

DOI=10.3389/fphy.2018.00116

ISSN=2296-424X

ABSTRACT=<p>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. <italic>In vitro</italic> experiments exposed bovine AC samples to either simultaneous sonication and immersion in MB (Treatment 1; <italic>n</italic> = 10), immersion in MB after sonication (Control 1; <italic>n</italic> = 10), solely immersion in MB (Control 2; <italic>n</italic> = 10), or neither sonication nor immersion in MB (Control 3; <italic>n</italic> = 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 μm depth from AC surface as compared to all controls. Field emission scanning electron microscopy (FESEM), histological analysis, and digital densitometry (DD) of sonicated (<italic>n</italic> = 6) and non-sonicated (<italic>n</italic> = 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.</p>