Abstract
Recent studies have illustrated the profound dependence of cellular behavior on the stiffness of 2D culture substrates. The goal of this study was to develop a method to alter the stiffness cells experience in a standard 3D collagen gel model without affecting the physiochemical properties of the extracellular matrix. A device was developed utilizing compliant anchors (0.048–0.64 N m−1) to tune the boundary stiffness of suspended collagen gels in between the commonly utilized free and fixed conditions (zero and infinite stiffness boundary stiffness). We demonstrate the principle of operation with finite element analyses and a wide range of experimental studies. In all cases, boundary stiffness has a strong influence on cell behavior, most notably eliciting higher basal tension and activated force (in response to KCl) and more pronounced remodeling of the collagen matrix at higher boundary stiffness levels. Measured equibiaxial forces for gels seeded with 3 million human foreskin fibroblasts range from 0.05 to 1 mN increasing monotonically with boundary stiffness. Estimated force per cell ranges from 17 to 100 nN utilizing representative volume element analysis. This device provides a valuable tool to independently study the effect of the mechanical environment of the cell in a 3D collagen matrix.
Similar content being viewed by others
References
Arora, P., N. Narani, and C. McCulloch. The compliance of collagen gels regulates transforming growth factor-beta induction of alpha-smooth muscle actin in fibroblasts. Am. J. Pathol. 154(3):871–882, 1999.
Balestrini, J. L., and K. L. Billiar. Equibiaxial cyclic stretch stimulates fibroblasts to rapidly remodel fibrin. J. Biomech. 39(16):2983–2990, 2006.
Bell, E., B. Ivarsson, and C. Merrill. Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative potential in vitro. Proc. Natl. Acad. Sci. USA 76(3):1274–1278, 1979.
Billiar, K. L., A. M. Throm, and M. T. Frey. Biaxial failure properties of planar living tissue equivalents. J. Biomed. Mater. Res. A 73(2):182–191, 2005.
Brown, R. A., K. K. Sethi, I. Gwanmesia, D. Raemdonck, M. Eastwood, and V. Mudera. Enhanced fibroblast contraction of 3D collagen lattices and integrin expression by TGF-beta1 and -beta3: mechanoregulatory growth factors? Exp. Cell Res. 274(2):310–322, 2002.
Campbell, B., W. Clark, and J. Wang. A multi-station culture force monitor system to study cellular contractility. J. Biomech. 36(1):137–140, 2003.
Carlson, M., M. Longaker, and J. Thompson. Wound splinting regulates granulation tissue survival. J. Surg. Res. 110(1):304–309, 2003.
Chen, J., H. Li, N. Sundarraj, and J. H. Wang. Alpha-smooth muscle actin expression enhances cell traction force. Cell Motil. Cytoskeleton 64(4):248–257, 2007.
Chevallay, B., and D. Herbage. Collagen-based biomaterials as 3D scaffold for cell cultures: applications for tissue engineering and gene therapy. Med. Biol. Eng. Comput. 38(2):211–218, 2000.
Cukierman, E., R. Pankov, D. R. Stevens, and K. M. Yamada. Taking cell-matrix adhesions to the third dimension. Science 294(5547):1708–1712, 2001.
Delvoye, P., P. Wiliquet, J. L. Leveque, B. V. Nusgens, and C. M. Lapiere. Measurement of mechanical forces generated by skin fibroblasts embedded in a three-dimensional collagen gel. J. Invest. Dermatol. 97(5):898–902, 1991.
Desmouliere, A., C. Badid, M. L. Bochaton-Piallat, and G. Gabbiani. Apoptosis during wound healing, fibrocontractive diseases and vascular wall injury. Int. J. Biochem. Cell Biol. 29(1):19–30, 1997.
Desmouliere, A., A. Geinoz, F. Gabbiani, and G. Gabbiani. Transforming growth factor-beta 1 induces alpha-smooth muscle actin expression in granulation tissue myofibroblasts and in quiescent and growing cultured fibroblasts. J. Cell Biol. 122(1):103–111, 1993.
Discher, D., P. Janmey, and Y. Wang. Tissue cells feel and respond to the stiffness of their substrate. Science 310(5751):1139–1143, 2005.
Eastwood, M., D. A. McGrouther, and R. A. Brown. A culture force monitor for measurement of contraction forces generated in human dermal fibroblast cultures: evidence for cell-matrix mechanical signalling. Biochim. Biophys. Acta 1201(2):186–192, 1994.
Eastwood, M., R. Porter, U. Khan, G. McGrouther, and R. Brown. Quantitative analysis of collagen gel contractile forces generated by dermal fibroblasts and the relationship to cell morphology. J. Cell. Physiol. 166(1):33–42, 1996.
Elsdale, T., and J. Bard. Collagen substrata for studies on cell behavior. J. Cell Biol. 54(3):626–637, 1972.
Engler, A. J., S. Sen, H. L. Sweeney, and D. E. Discher. Matrix elasticity directs stem cell lineage specification. Cell 126(4):677–689, 2006.
Fluck, J., C. Querfeld, A. Cremer, S. Niland, T. Krieg, and S. Sollberg. Normal human primary fibroblasts undergo apoptosis in three-dimensional contractile collagen gels. J. Invest. Dermatol. 110(2):153–157, 1998.
Freyman, T., I. Yannas, R. Yokoo, and L. Gibson. Fibroblast contractile force is independent of the stiffness which resists the contraction. Exp. Cell Res. 272(2):153–162, 2002.
Gabbiani, G. The myofibroblast in wound healing and fibrocontractive diseases. J. Pathol. 200(4):500–503, 2003.
Girton, T. S., T. R. Oegema, E. D. Grassl, B. C. Isenberg, and R. T. Tranquillo. Mechanisms of stiffening and strengthening in media-equivalents fabricated using glycation. J. Biomech. Eng. 122(3):216–223, 2000.
Grinnell, F. Fibroblasts, myofibroblasts, and wound contraction. J. Cell Biol. 124(4):401–404, 1994.
Grinnell, F. Fibroblast biology in three-dimensional collagen matrices. Trends Cell Biol. 13(5):264–269, 2003.
Harley, B., T. Freyman, M. Wong, and L. Gibson. A new technique for calculating individual dermal fibroblast contractile forces generated within collagen-GAG scaffolds. Biophys. J. 93(8):2911–2922, 2007.
Hinz, B., D. Mastrangelo, C. Iselin, C. Chaponnier, and G. Gabbiani. Mechanical tension controls granulation tissue contractile activity and myofibroblast differentiation. Am. J. Pathol. 159(3):1009–1020, 2001.
Hinz, B., S. Phan, V. Thannickal, A. Galli, M. Bochaton-Piallat, and G. Gabbiani. The myofibroblast: one function, multiple origins. Am. J. Pathol. 170(6):1807–1816, 2007.
Huang, S., and D. Ingber. Cell tension, matrix mechanics, and cancer development. Cancer Cell 8(3):175–176, 2005.
Ibusuki, S., G. J. Halbesma, M. A. Randolph, R. W. Redmond, I. E. Kochevar, and T. J. Gill. Photochemically cross-linked collagen gels as three-dimensional scaffolds for tissue engineering. Tissue Eng. 13(8):1995–2001, 2007.
Ingber, D. E., D. Prusty, Z. Sun, H. Betensky, and N. Wang. Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis. J. Biomech. 28(12):1471–1484, 1995.
Jiang, H., S. Rhee, C. H. Ho, and F. Grinnell. Distinguishing fibroblast promigratory and procontractile growth factor environments in 3-D collagen matrices. FASEB J. 22(7):2151–2160, 2008.
Ju, B. F., K.-K. Liu, S.-F. Ling, and W. Hong Ng. A novel technique for characterizing elastic properties of thin biological membrane. Mech. Mater. 34(11):749–754, 2002.
Junker, J. P., C. Kratz, A. Tollback, and G. Kratz. Mechanical tension stimulates the transdifferentiation of fibroblasts into myofibroblasts in human burn scars. Burns 34(7):942–946, 2008.
Karamichos, D., R. A. Brown, and V. Mudera. Complex dependence of substrate stiffness and serum concentration on cell-force generation. J. Biomed. Mater. Res. A 78(2):407–415, 2006.
Karamichos, D., R. A. Brown, and V. Mudera. Collagen stiffness regulates cellular contraction and matrix remodeling gene expression. J. Biomed. Mater. Res. A 83(3):887–894, 2007.
Karamichos, D., J. Skinner, R. Brown, and V. Mudera. Matrix stiffness and serum concentration effects matrix remodelling and ECM regulatory genes of human bone marrow stem cells. J. Tissue Eng. Regen. Med. 2(2–3):97–105, 2008.
Kershaw, J. D., M. Misfeld, H. H. Sievers, M. H. Yacoub, and A. H. Chester. Specific regional and directional contractile responses of aortic cusp tissue. J. Heart Valve Dis. 13(5):798–803, 2004.
Knapp, D., T. Tower, R. Tranquillo, and V. H. Barocas. Estimation of cell traction and migration in an isometric cell traction assay. AIChE J. 45(12):2628–2640, 1999.
Knezevic, V., A. J. Sim, T. K. Borg, and J. W. Holmes. Isotonic biaxial loading of fibroblast-populated collagen gels: a versatile, low-cost system for the study of mechanobiology. Biomech. Model. Mechanobiol. 1(1):59–67, 2002.
Kolodney, M. S., and R. B. Wysolmerski. Isometric contraction by fibroblasts and endothelial cells in tissue culture: a quantitative study. J. Cell Biol. 117(1):73–82, 1992.
Legant, W. R., A. Pathak, M. T. Yang, V. S. Deshpande, R. M. McMeeking, and C. S. Chen. Microfabricated tissue gauges to measure and manipulate forces from 3D microtissues. Proc. Natl. Acad. Sci. USA 106(25):10097–10102, 2009.
Mazzolai, L., T. Pedrazzini, F. Nicoud, G. Gabbiani, H. R. Brunner, and J. Nussberger. Increased cardiac angiotensin II levels induce right and left ventricular hypertrophy in normotensive mice. Hypertension 35(4):985–991, 2000.
Moulin, V., B. Y. Tam, G. Castilloux, F. A. Auger, M. D. O’Connor-McCourt, A. Philip, and L. Germain. Fetal and adult human skin fibroblasts display intrinsic differences in contractile capacity. J. Cell. Physiol. 188(2):211–222, 2001.
Nelson, C. M., R. P. Jean, J. L. Tan, W. F. Liu, N. J. Sniadecki, A. A. Spector, and C. S. Chen. Emergent patterns of growth controlled by multicellular form and mechanics. Proc. Natl. Acad. Sci. USA 102(33):11594–11599, 2005.
Nguyen, K. T., and J. L. West. Photopolymerizable hydrogels for tissue engineering applications. Biomaterials 23(22):4307–4314, 2002.
Nishiyama, T., N. Tominaga, K. Nakajima, and T. Hayashi. Quantitative evaluation of the factors affecting the process of fibroblast-mediated collagen gel contraction by separating the process into three phases. Coll. Relat. Res. 8(3):259–273, 1988.
Pedersen, J. A., and M. A. Swartz. Mechanobiology in the third dimension. Ann. Biomed. Eng. 33(11):1469–1490, 2005.
Peyton, S. R., C. M. Ghajar, C. B. Khatiwala, and A. J. Putnam. The emergence of ECM mechanics and cytoskeletal tension as important regulators of cell function. Cell Biochem. Biophys. 47(2):300–320, 2007.
Redden, R. A., and E. J. Doolin. Collagen crosslinking and cell density have distinct effects on fibroblast-mediated contraction of collagen gels. Skin Res. Technol. 9(3):290–293, 2003.
Rowlands, A., P. George, and J. Cooper-White. Directing osteogenic and myogenic differentiation of MSCs: interplay of stiffness and adhesive ligand presentation. Am. J. Physiol. Cell Physiol. 295(4):C1037–C1044, 2008.
Shapira-Schweitzer, K., and D. Seliktar. Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial. Acta Biomater. 3(1):33–41, 2007.
Tamariz, E., and F. Grinnell. Modulation of fibroblast morphology and adhesion during collagen matrix remodeling. Mol. Biol. Cell 13(11):3915–3929, 2002.
Thomopoulos, S., G. M. Fomovsky, and J. W. Holmes. The development of structural and mechanical anisotropy in fibroblast populated collagen gels. J. Biomech. Eng. 127(5):742–750, 2005.
Tomasek, J., G. Gabbiani, B. Hinz, C. Chaponnier, and R. Brown. Myofibroblasts and mechano-regulation of connective tissue remodelling. Nat. Rev. Mol. Cell Biol. 3(5):349–363, 2002.
Torres, D. S., T. M. Freyman, I. V. Yannas, and M. Spector. Tendon cell contraction of collagen-GAG matrices in vitro: effect of cross-linking. Biomaterials 21(15):1607–1619, 2000.
Walker, G., K. Masters, D. Shah, K. Anseth, and L. Leinwand. Valvular myofibroblast activation by transforming growth factor-beta: implications for pathological extracellular matrix remodeling in heart valve disease. Circ. Res. 95(3):253–260, 2004.
Zaman, M., L. Trapani, A. Sieminski, A. Siemeski, D. Mackellar, H. Gong, R. Kamm, A. Wells, D. Lauffenburger, and P. Matsudaira. Migration of tumor cells in 3D matrices is governed by matrix stiffness along with cell-matrix adhesion and proteolysis. Proc. Natl. Acad. Sci. USA 103(29):10889–10894, 2006.
Zhu, Y. K., T. Umino, X. D. Liu, H. J. Wang, D. J. Romberger, J. R. Spurzem, and S. I. Rennard. Contraction of fibroblast-containing collagen gels: initial collagen concentration regulates the degree of contraction and cell survival. In Vitro Cell Dev. Biol. Anim. 37(1):10–16, 2001.
Acknowledgments
The authors would like to thank Jacquelyn Youssef for her technical assistance in the laboratory. This work was supported in part by the American Heart Association Grant SDG 0535265N (KLB) and the National Institutes of Health 1R15HL087257 (KLB). The authors have no financial relationships that represent conflicts of interest.
Author information
Authors and Affiliations
Corresponding author
Appendix
Appendix
Estimation of the Force Per Cell Using the RVE Method
To estimate the average force per cell, we assume that the cells are oriented randomly in the plane of the tissue, and that each cell pulls predominantly in one direction (i.e., bipolar cells). Using the RVE method, the total force measured along one axis, F T, can be computed from the average force per cell, F C, by integration:
where n E is the number of cells in parallel (RVEs a cross-section), and R(θ) is the angular distribution of cells. If the distribution of cells orientations is assumed uniform (constant with θ), and we note that the integral of R(θ) = 1 by definition, then:
Thus, F C = F T/2n E in our system.
To determine the size of an RVE, the final volume of the gel is calculated by multiplying the projected area (from digital images, e.g., Fig. 8a) by the thickness (from histological sections, e.g., Fig. 8d) and is divided by the total number of cells in the gel. The number of cells (RVEs) contributing to the total force is estimated by dividing the cross-sectional area in the central region of interest perpendicular to the axis on which force is measured by the cross-sectional area of the RVE which is assumed to be a cube. As the shape of the contracted gel is roughly cruciform, the width of the region of interest is approximately half of the maximum dimension of the gel.
Rights and permissions
About this article
Cite this article
John, J., Throm Quinlan, A., Silvestri, C. et al. Boundary Stiffness Regulates Fibroblast Behavior in Collagen Gels. Ann Biomed Eng 38, 658–673 (2010). https://doi.org/10.1007/s10439-009-9856-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10439-009-9856-1