title: Tension is required for fibripositor formation.
abstract: Embryonic tendon cells (ETCs) have actin-rich fibripositors that accompany parallel bundles of collagen fibrils in the extracellular matrix. To study fibripositor function, we have developed a three-dimensional cell culture system that promotes and maintains fibripositors. We show that ETCs cultured in fixed-length fibrin gels replace the fibrin during ~6 days in culture with parallel bundles of narrow-diameter collagen fibrils that are uniaxially aligned with fibripositors, thereby generating a tendon-like construct. Fibripositors occurred simultaneously with onset of parallel collagen fibrils. Interestingly, the constructs have a tendon-like crimp. In initial experiments to study the effects of tension, we showed that cutting the constructs resulted in loss of tension, loss of fibripositors and the appearance of immature fibrils with no preferred orientation.
authors.affiliation: Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Faculty of Life Sciences, Michael Smith Building, Oxford Road, Manchester M13 9PT, England, United Kingdom.
authors.forename: Zoher
authors.initials: Z
authors.lastname: Kapacee
authors.forename: Susan H
authors.initials: SH
authors.lastname: Richardson
authors.forename: Yinhui
authors.initials: Y
authors.lastname: Lu
authors.forename: Tobias
authors.initials: T
authors.lastname: Starborg
authors.forename: David F
authors.initials: DF
authors.lastname: Holmes
authors.forename: Keith
authors.initials: K
authors.lastname: Baar
authors.forename: Karl E
authors.initials: KE
authors.lastname: Kadler
mesh_terms: D000818:Animals; D002642:Chick Embryo; D005109:Extracellular Matrix / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D013314:Stress, Mechanical; D013710:Tendons