Cells interpret their mechanical environment using diverse signaling pathways that affect complex phenotypes. These pathways often interact with ubiquitous 2 nd-messengers such as calcium. Understanding mechanically-induced calcium signaling is especially important in fibroblasts, cells that exist in three-dimensional fibrous matrices, sense their mechanical environment, and remodel tissue morphology. Here, we examined calcium signaling in fibroblasts using a minimal-profile, three-dimensional (MP3D) mechanical assay system, and compared responses to those elicited by conventional, two-dimensional magnetic tensile cytometry and substratum stretching. Using the MP3D system, we observed robust mechanically-induced calcium responses that could not be recreated using either two-dimensional technique. Furthermore, we used the MP3D system to identify a critical displacement threshold governing an all-or-nothing mechanically-induced calcium response. We believe these findings significantly increase our understanding of the critical role of calcium signaling in cells in three-dimensional environments with broad implications in development and disease.
Bibliographical noteFunding Information:
The authors thank Professor C.M. Cheng for technical assistance with SEM imaging. This work was supported in part by the National Science Foundation (CMMI-0856187 and CMMI-1160840) and the Office of Naval Research (N000140910215). W.C.R. was supported by a Dowd-ICES predoctoral fellowship awarded by CMU as well as by the NIH-NIBIB training grant T32 EB0003392 entitled ‘Biomechanics in Regenerative Medicine’. E.D.P. and N.Z.D.B. were supported in part by a REU supplement to NSF grant EF-0331657 at the CMU Center for Bioimage Informatics. Certain commercial equipment, instruments, or materials are identified in this document. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose.