title: Quantifying cell-generated mechanical forces within living embryonic tissues.
abstract: Cell-generated mechanical forces play a critical role during tissue morphogenesis and organ formation in the embryo. Little is known about how these forces shape embryonic organs, mainly because it has not been possible to measure cellular forces within developing three-dimensional (3D) tissues in vivo. We present a method to quantify cell-generated mechanical stresses exerted locally within living embryonic tissues, using fluorescent, cell-sized oil microdroplets with defined mechanical properties and coated with adhesion receptor ligands. After a droplet is introduced between cells in a tissue, local stresses are determined from droplet shape deformations, measured using fluorescence microscopy and computerized image analysis. Using this method, we quantified the anisotropic stresses generated by mammary epithelial cells cultured within 3D aggregates, and we confirmed that these stresses (3.4 nN μm(-2)) are dependent on myosin II activity and are more than twofold larger than stresses generated by cells of embryonic tooth mesenchyme, either within cultured aggregates or in developing whole mouse mandibles.
authors: 1] School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA. [2] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA. [3] Vascular Biology Program, Children's Hospital, Boston, Massachusetts, USA. [4] Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA. [5].
authors: Otger
authors: O
authors: Campàs
authors: Vascular Biology Program, Children's Hospital, Boston, Massachusetts, USA.
authors: Tadanori
authors: T
authors: Mammoto
authors: Vascular Biology Program, Children's Hospital, Boston, Massachusetts, USA.
authors: Sean
authors: S
authors: Hasso
authors: School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA.
authors: Ralph A
authors: RA
authors: Sperling
authors: Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
authors: Daniel
authors: D
authors: O'Connell
authors: 1] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA. [2] Vascular Biology Program, Children's Hospital, Boston, Massachusetts, USA.
authors: Ashley G
authors: AG
authors: Bischof
authors: Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
authors: Richard
authors: R
authors: Maas
authors: 1] School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA. [2] Department of Physics, Harvard University, Cambridge, Massachusetts, USA.
authors: David A
authors: DA
authors: Weitz
authors: 1] School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA. [2] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA. [3] Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Department of Physics, Harvard University, Cambridge, Massachusetts, USA.
authors: L
authors: L
authors: Mahadevan
authors: 1] School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA. [2] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA. [3] Vascular Biology Program, Children's Hospital, Boston, Massachusetts, USA. [4] Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
authors: Donald E
authors: DE
authors: Ingber
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002449:Cell Aggregation / Q000502:physiology*; D002454:Cell Differentiation; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D005260:Female; D019426:Integrases / Q000378:metabolism; D053547:Keratin-14 / Q000502:physiology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009024:Morphogenesis; D024462:Myosin Type II / Q000378:metabolism; D013314:Stress, Mechanical; D014070:Tooth / Q000254:growth & development / Q000378:metabolism*
chemical_list: D053547:Keratin-14; C507446:Krt14 protein, mouse; C045073:Cre recombinase; D019426:Integrases; D024462:Myosin Type II