Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Subscribe

Logo for

PNAS 102 (33): 11594-11599

Copyright © 2005 by the National Academy of Sciences.

Emergent patterns of growth controlled by multicellular form and mechanics

Celeste M. Nelson *, {dagger}, Ronald P. Jean *, John L. Tan *, Wendy F. Liu *, Nathan J. Sniadecki *, Alexander A. Spector *, and Christopher S. Chen *, {dagger}, {ddagger}

*Departments of Biomedical Engineering and Oncology, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205; and {ddagger}Department of Bioengineering, University of Pennsylvania, Translational Research Labs Suite 1400, 125 South 31st Street, Philadelphia, PA 19104



View larger version (49K):

[in a new window]
 
Fig. 1. Method for detecting spatial variations in proliferation in sheets of cells. (A) Phase contrast image of cells on a small (250-µm edge) square island. (B) Fluorescence image of monolayer showing actin (red), VE-cadherin (green), and nuclei (blue). (C) Fluorescence image of cell proliferation (BrdUrd incorporation) in one island of cells. (D) Colorimetric stacked image of cell proliferation. A pixel value of 0.20 indicates that 20% of cells at that location proliferated. (E) Fluorescence image of all nuclei (stained with DAPI) in one island of cells. (F) Colorimetric stacked image of all nuclei showing a uniform distribution of cells in the monolayers. The pattern of proliferation is defined by the geometry of the island of cells. (GJ) Colorimetric stacked images of cell proliferation in small (250-µm edge) square (G), large (500-µm edge) square (H), small (125 x 500 µm) rectangular (I), and large (564-µm diameter) circular (J) islands. Statistical analysis is presented in Fig. 5. (Scale bars, 100 µm.)

 


View larger version (46K):

[in a new window]
 
Fig. 2. The pattern of proliferation corresponds to predicted local mechanical stresses. (A) FEM mesh of contracting monolayer. (B) FEM calculations of relative maximum principal tractional stress exerted by cells in a small square island. (CE) Cells cultured on annulus. Shown are phase contrast (C), FEM results (D), and colorimetric stacked image of cell proliferation (E). (FH) Cells cultured on asymmetric annulus. Shown are phase contrast (F), FEM results (G), and colorimetric stacked image of cell proliferation (H). Outer diameter is 346 µm; inner diameter is 200 µm; center of asymmetric hole is 30 µm from the center of the island. Statistical analysis is presented in Fig. 5. (Scale bars, 100 µm.)

 


View larger version (99K):

[in a new window]
 
Fig. 3. Mechanical forces generated by cytoskeletal contraction cause the patterns of proliferation. (AC) Cells cultured on elastomeric force sensor array. Shown are phase contrast image (A), vector map of traction forces measured at edges (B), and colorimetric map of traction forces measured over the entire monolayer (nN) (C). (DI) Colorimetric images of cell proliferation for cells cultured on asymmetric annulus and left untreated (D), treated with Y-27632 (E), infected with Ad-RhoAV14 (F), simultaneously treated with Y-27632 and infected with Ad-RhoAV14 (G), infected with Ad-VE{Delta} (H), or coinfected with Ad-VE{Delta} and Ad-RhoAV14 (I). Reference arrow in B indicates 50 nN of force. Statistical analysis is presented in Fig. 5. (Scale bars, 100 µm.)

 


View larger version (66K):

[in a new window]
 
Fig. 4. Patterned proliferation corresponds to mechanical stresses in cellular aggregates that lack edges. (AE) Monolayer of cells on pyramidal array. Shown are scanning electron microscopy of substratum surface (A), phase contrast merged with fluorescence image of nuclei (B), FEM results (C), colorimetric stacked image of cell proliferation (D), and colorimetric image of cell proliferation when treated with Y-27632 (E). Tetrahedrons are pointed upward. Statistical analysis is presented in Fig. 5. (Scale bars, 100 µm.)

 


To Advertise     Find Products


Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882