During development, mesenchymal cells direct the elaboration of extracellular matrix that shapes the initial animal bauplan which subsequently grows to produce mechanically-competent structure. To gain insight into the processes that initiate matrix formation at the cellular level, high temporal and spatial resolution videos were obtained from a primary human corneal fibroblast (PHCF) cell culture system known to produce an organized, collagenous stroma similar to a human cornea. The images were taken over a 4-day period prior to culture confluency which permitted a clear view of the cell kinematics and any elaborated filaments. The movies reveal an active cellular system in which the PHCFs execute five types of high-velocity and high extensional strain-rate 'pulls' that produce persistent filaments. In four of the pull types, average maximum strain rates (~0.1-0.33s-1) were adequate to induce aggregation and/or crystallization in crowded biopolymer systems. The results demonstrate that PHCFs have the capacity to mechanically induce the formation of biopolymer structures intercellularly and in the path of force.
Mechanical Causation of Biological Structure: Productive Pulls Produce Persistent Filaments in a Human Fibroblast Model of Matrix Development
