Suspended Tissue Open Microfluidic Patterning (STOMP).

Cell-laden hydrogel constructs suspended between pillars are powerful tools for modeling tissue structure and physiology, though current fabrication techniques often limit them to uniform compositions. In contrast, tissues are complex in nature with spatial arrangements of cell types and extracellular matrices. Thus, we present Suspended Tissue Open Microfluidic Patterning (STOMP), which utilizes a removable, open microfluidic patterning channel to pattern multiple spatial regions across a single suspended tissue.

Stepwise Stiffening/Softening of and Cell Recovery from Reversibly Formulated Hydrogel Interpenetrating Networks.

Biomechanical contributions of the extracellular matrix underpin cell growth and proliferation, differentiation, signal transduction, and other fate decisions. As such, biomaterials whose mechanics can be spatiotemporally altered- particularly in a reversible manner- are extremely valuable for studying these mechanobiological phenomena. Herein, a poly(ethylene glycol) (PEG)-based hydrogel model consisting of two interpenetrating step-growth networks is introduced that are independently formed via largely orthogonal bioorthogonal chemistries and sequentially degraded with distinct recombinant sortases, affording reversibly tunable stiffness ranges that span healthy and diseased soft tissues (e.

Stepwise Stiffening/Softening of and Cell Recovery from Reversibly Formulated Hydrogel Double Networks.

Biomechanical contributions of the ECM underpin cell growth and proliferation, differentiation, signal transduction, and other fate decisions. As such, biomaterials whose mechanics can be spatiotemporally altered - particularly in a reversible manner - are extremely valuable for studying these mechanobiological phenomena. Herein, we introduce a poly(ethylene glycol) (PEG)-based hydrogel model consisting of two interpenetrating step-growth networks that are independently formed via largely orthogonal bioorthogonal chemistries and sequentially degraded with distinct bacterial transpeptidases, affording reversibly tunable stiffness ranges that span healthy and diseased soft tissues (e.

De novo design of modular protein hydrogels with programmable intra- and extracellular viscoelasticity.

Relating the macroscopic properties of protein-based materials to their underlying component microstructure is an outstanding challenge. Here, we exploit computational design to specify the size, flexibility, and valency of de novo protein building blocks, as well as the interaction dynamics between them, to investigate how molecular parameters govern the macroscopic viscoelasticity of the resultant protein hydrogels. We construct gel systems from pairs of symmetric protein homo-oligomers, each comprising 2, 5, 24, or 120 individual protein components, that are crosslinked either physically or covalently into idealized step-growth biopolymer networks.

Pharmacological regulation of protein-polymer hydrogel stiffness.

The extracellular matrix (ECM) undergoes constant physiochemical change. User-programmable biomaterials afford exciting opportunities to study such dynamic processes . Herein, we introduce a protein-polymer hydrogel whose stiffness can be pharmacologically and reversibly regulated with conventional antibiotics.

De novo design of modular protein hydrogels with programmable intra- and extracellular viscoelasticity.

Relating the macroscopic properties of protein-based materials to their underlying component microstructure is an outstanding challenge. Here, we exploit computational design to specify the size, flexibility, and valency of protein building blocks, as well as the interaction dynamics between them, to investigate how molecular parameters govern the macroscopic viscoelasticity of the resultant protein hydrogels. We construct gel systems from pairs of symmetric protein homo-oligomers, each comprising 2, 5, 24, or 120 individual protein components, that are crosslinked either physically or covalently into idealized step-growth biopolymer networks.

User-Controlled 4D Biomaterial Degradation with Substrate-Selective Sortase Transpeptidases for Single-Cell Biology.

Stimuli-responsive biomaterials show great promise for modeling disease dynamics ex vivo with spatiotemporal control over the cellular microenvironment. However, harvesting cells from such materials for downstream analysis without perturbing their state remains an outstanding challenge in 3/4-dimensional (3D/4D) culture and tissue engineering. In this manuscript, a fully enzymatic strategy for hydrogel degradation that affords spatiotemporal control over cell release while maintaining cytocompatibility is introduced.

Correcting dilated cardiomyopathy with fibroblast-targeted p38 deficiency.

Inherited mutations in contractile and structural genes, which decrease cardiomyocyte tension generation, are principal drivers of dilated cardiomyopathy (DCM)- the leading cause of heart failure . Progress towards developing precision therapeutics for and defining the underlying determinants of DCM has been cardiomyocyte centric with negligible attention directed towards fibroblasts despite their role in regulating the best predictor of DCM severity, cardiac fibrosis . Given that failure to reverse fibrosis is a major limitation of both standard of care and first in class precision therapeutics for DCM, this study examined whether cardiac fibroblast-mediated regulation of the heart's material properties is essential for the DCM phenotype.

MBNL1 drives dynamic transitions between fibroblasts and myofibroblasts in cardiac wound healing.

Dynamic fibroblast to myofibroblast state transitions underlie the heart's fibrotic response. Because transcriptome maturation by muscleblind-like 1 (MBNL1) promotes differentiated cell states, this study investigated whether tactical control of MBNL1 activity could alter myofibroblast activity and fibrotic outcomes. In healthy mice, cardiac fibroblast-specific overexpression of MBNL1 transitioned the fibroblast transcriptome to that of a myofibroblast and after injury promoted myocyte remodeling and scar maturation.

Magnetically-propelled fecal surrogates for modeling the impact of solid-induced shear forces on primary colonic epithelial cells.

The colonic epithelium is continuously exposed to an array of biological and mechanical stimuli as its luminal contents are guided over the epithelial surface through regulated smooth muscle contraction. In this report, the propulsion of solid fecal contents over the colonic epithelium is recapitulated through noninvasive actuation of magnetic agarose hydrogels over primary intestinal epithelial cultures, in contrast to the vast majority of platforms that apply shear forces through liquid microflow. Software-controlled magnetic stepper motors enable experimental control over the frequency and velocity of these events to match in vivo propulsive contractions, while the integration of standardized well plate spacing facilitates rapid integration into existing assay pipelines.

The Art of Engineering Biomimetic Cellular Microenvironments.

Cells and their surrounding microenvironment exist in dynamic reciprocity, where bidirectional feedback and feedforward crosstalk drives essential processes in development, homeostasis, and disease. With the ongoing explosion of customizable biomaterial innovation for dynamic cell culture, an ever-expanding suite of user-programmable scaffolds now exists to probe cell fate in response to spatiotemporally controlled biophysical and biochemical cues. Here, we highlight emerging trends in these efforts, emphasizing strategies that offer tunability over complex network mechanics, present biomolecular cues anisotropically, and harness cells as physiochemical actuators of the pericellular niche.

Layer-by-layer fabrication of 3D hydrogel structures using open microfluidics.

Patterned deposition and 3D fabrication techniques have enabled the use of hydrogels for a number of applications including microfluidics, sensors, separations, and tissue engineering in which form fits function. Devices such as reconfigurable microvalves or implantable tissues have been created using lithography or casting techniques. Here, we present a novel open-microfluidic patterning method that utilizes surface tension forces to form hydrogel layers on top of each other, into a patterned 3D structure.

Elastic, silk-cardiac extracellular matrix hydrogels exhibit time-dependent stiffening that modulates cardiac fibroblast response.

Heart failure is the leading cause of death in the United States and rapidly becoming the leading cause of death worldwide. While pharmacological treatments can reduce progression to heart failure following myocardial infarction, there still exists a need for new therapies that promote better healing postinjury for a more functional cardiac repair and methods to understand how the changes to tissue mechanical properties influence cell phenotype and function following injury. To address this need, we have optimized a silk-based hydrogel platform containing cardiac tissue-derived extracellular matrix (cECM).