Decoupling the effects of stiffness and fiber density on cellular behaviors via an interpenetrating network of gelatin-methacrylate and collagen

Abstract

The extracellular microenvironment provides critical cues that guide tissue development, homeostasis, and pathology. Deciphering the individual roles of these cues in tissue function necessitates the development of physically tunable culture platforms, but current approaches to create such materials have produced scaffolds that either exhibit a limited mechanical range or are unable to recapitulate the fibrous nature of in vivo tissues. Here we report a novel interpenetrating network (IPN) of gelatin-methacrylate (gelMA) and collagen I that enables independent tuning of fiber density and scaffold stiffness across a physiologically-relevant range of shear moduli (2–12 kPa), while maintaining constant extracellular matrix content. This biomaterial system was applied to examine how changes in the physical microenvironment affect cell types associated with the tumor microenvironment. By increasing fiber density while maintaining constant stiffness, we found that MDA-MB-231 breast tumor cells required the presence of fibers to invade the surrounding matrix, while endothelial cells (ECs) did not. Meanwhile, increasing IPN stiffness independently of fiber content yielded decreased invasion and sprouting for both MDA-MB-231 cells and ECs. These results highlight the importance of decoupling features of the microenvironment to uncover their individual effects on cell behavior, in addition to demonstrating that individual cell types within a tissue may be differentially affected by the same changes in physical features. The mechanical range and fibrous nature of this tunable biomaterial platform enable mimicry of a wide variety of tissues, and may yield more precise identification of targets which may be exploited to develop interventions to control tissue function.

Sequential modes of crosslinking tune viscoelasticity of cell-instructive hydrogels

“…Fibrillar collagen can be challenging to incorporate and maintain in three-dimensional matrices, because its fibers can be inhibited or altered by changes in collagen content and matrix crosslinking mode and density. Collagen type I can form interpenetrating networks with hydrogels formed with non-covalently [20] or dynamic covalently [17] crosslinked polymers, as well as methacrylated-gelatin [21]. However, none of these studies have reported that collagen fiber architecture can be maintained independent of matrix viscoelasticity.…”

In Vitro Study of Colon Cancer Cell Migration Using E‐Jet 3D Printed Cell Culture Platforms

“…The influence of 3D fibrillar structures on cellular outcomes has been highlighted in recent studies in which a wide variety of tissues have been mimicked . Aligned fibers in tumors have been shown to play an important role in directing cancer cell behavior during tumor metastasis and fiber alignment can be used as a paradigm for predicting human breast cancer survival .…”

“…Tumor cells require the presence of fibers to invade the surrounding stroma . These fibers not only provide biological cues to embedded cells, but also uniquely influence cell–cell communication and alignment, in addition to the degree of cell contraction . Techniques have been developed recently to construct cell culture platforms, including microfabrication, selective laser sintering, phase separation, stereo lithography, electrospinning, fused filament fabrication, and 3D printing .…”

Electric field-driven building blocks for introducing multiple gradients to hydrogels

“…Cell fates could be determined by mechanical cues (Han et al, 2016;Wang et al, 2018a;Liu et al, 2019). The cells sense mechanical signals and secret different growth factors to control the differentiation, proliferation and migration behaviors (Berger et al, 2017;Pogoda et al, 2017). It is considered that the modulus of 18-28 kPa could induce the differentiation of stem cells to chondrocytes while the modulus of above 28 kPa would stimulate the osteo-differentiation (Engler et al, 2006;Ding et al, 2017.09).…”

“…Gelatin methacryloyl (Gel-MA, EFL-GM-90, Suzhou Intelligent Manufacturing Research Institute, Suzhou, China) and N-isopropylacrylamide (NIPAM, Aladdin Chemistry Co. Ltd, Shanghai, China) were chosen as the models of natural and synthetic biomaterials and blended with BSNF solution. According to previous studies (Berger et al, 2017;Gao et al, 2019), the freeze-dried Gel-MA was dissolved in lithium phenyl-2,4, 6-trimethylbenzoylphosphinate (LAP, EFL-LAP, Suzhou Intelligent Manufacturing Research Institute, Suzhou, China). The Gel-MA solution was blended with BSNF solution (2 wt%) at the volume ratio of 1:1.…”