Center for Biofilm Engineering

Abstract:  

"Loss of viability and induction of apoptosis in human keratinocytes exposed to Staphylococcus aureus biofilms in vitro"

09-026

Bacteria colonizing chronic wounds are believed to exist as polymicrobial, biofilm communities; however, there are few studies demonstrating the role of biofilms in chronic wound pathogenesis. This study establishes a novel method for studying the effect of biofilms on the cell types involved in wound healing. Cocultures of Staphylococcus aureus biofilms and human keratinocytes (HK) were created by initially growing S. aureus biofilms on tissue culture inserts then transferring the inserts to existing HK cultures. Biofilm-conditioned medium (BCM) was prepared by culturing the insert-supported biofilm in cell culture medium. As a control planktonic-conditioned medium (PCM) was also prepared. Biofilm, BCM, and PCM were used in migration, cell viability, and apoptosis assays. Changes in HK morphology were followed by brightfield and confocal microscopy. After only 3 hours exposure to BCM, but not PCM, HK formed dendrite-like extensions and displayed reduced viability. After 9 hours, there was an increase in apoptosis (p</=0.0004). At 24 hours, biofilm-, BCM-, and PCM-exposed HK all exhibited reduced scratch closure (p</=0.0001). The results demonstrated that soluble products of both S. aureus planktonic cells and biofilms inhibit scratch closure. Furthermore, S. aureus biofilms significantly reduced HK viability and significantly increased HK apoptosis compared with planktonic S. aureus.

Kirker KR, Secor PR, James GA, Fleckman P, Olerud JE, Stewart PS, "Loss of viability and induction of apoptosis in human keratinocytes exposed to Staphylococcus aureus biofilms in vitro," Wound Repair Regen 2009 Aug 11. [Epub ahead of print]