Comparison of contractile force generated by isolated and paired fibroblasts in vitro

Wound contraction is mediated by inter-connected fibroblasts that generate contractile forces on the extracellular matrix. To begin examining the contractile nature of inter-connected fibroblasts, the authors used an in vitro biophysical system to measure force generated by isolated (IF) and paired fibroblasts (PF). The biophysical system consists of collagen gel with fiduciary micro-beads that serve as reference points in the matrix. Fibroblasts cultured in DMEM with serum were trypsinized and plated on top of the collagen gel in serum free conditions. Images of IF or PF are digitized every minute for 30 minutes before and after application of lyso-phosphatidic acid (LPA), which induces fibroblast contraction. Contracting fibroblasts deform the collagen matrix resulting in displacement of fiduciary beads. Time lapse video microscopic analysis was used to track bead displacement every minute. Force generated by IF or PF were measured from bead displacement and matrix stiffness. Our preliminary results indicate that PFs generate relatively higher (p<0.05, two tailed t-test) contractile forces (mean force=(2.8±1.1)×10^-8 N, mean±SD, n=6), when compared to IFs ((1.5±0.9)×10^-8 N, n=6)