Disposition of Human Recombinant Lubricin in Naive Rats and in a Rat Model of Post-traumatic Arthritis After Intra-articular or Intravenous Administration

We have recently demonstrated that intra-articular (IA) administration of human recombinant lubricin, LUB:1, significantly inhibited cartilage degeneration and pain in the rat meniscal tear model of post-traumatic arthritis. In this report, we show that after a single IA injection to naive rats and rats that underwent unilateral meniscal tear, [125I]LUB:1 had a tri-phasic disposition profile, with the alpha, beta, and gamma half-life estimates of 4.5 h, 1.5 days, and 2.1 weeks, respectively. We hypothesize that the terminal phase kinetics was related to [125I]LUB:1 binding to its ligands. [125I]LUB:1 was detected on articular cartilage surfaces as long as 28 days after single IA injection. Micro-autoradiography analysis suggested that [125I]LUB:1 tended to localize to damaged joint surfaces in rats with meniscal tear. After a single intravenous (IV) dose to rats, [125I]LUB:1 was eliminated rapidly from the systemic circulation, with a mean total body clearance of 154 mL/h/kg and a mean elimination half-life (t 1/2) of 6.7 h. Overall, LUB:1 has met a desired disposition profile of a potential therapeutic intended for an IA administration: target tissue (knee) retention and fast elimination from the systemic circulation after a single IA or IV dose.