An in vitro platform for elucidating the molecular genetics of S. aureus invasion of the osteocyte lacuno-canalicular network during chronic osteomyelitis

Staphylococcus aureus osteomyelitis is a devasting disease that often leads to amputation. Recent findings have shown that S. aureus is capable of invading the osteocyte lacuno-canalicular network (OLCN) of cortical bone during chronic osteomyelitis. Normally a 1 mu m nonmotile cocci, S. aureus deforms smaller than 0.5 mu m in the sub-micron channels of the OLCN. Here we present the mu SiM-CA (Microfluidic - Silicon Membrane - Canalicular Array) as an in vitro screening platform for the genetic mechanisms of S. aureus invasion. The mu SiM-CA platform features an ultrathin silicon membrane with defined pores that mimic the openings of canaliculi. While we anticipated that S. aureus lacking the accessory gene regulator (agr) quorum-sensing system would not be capable of invading the OLCN, we found no differences in propagation compared to wild type in the mu SiM-CA. However the mu SiM-CA proved predictive as we also found that the agr mutant strain invaded the OLCN of murine tibiae. (C) 2019 Elsevier Inc. All rights reserved.