A Thy-1-negative immunofibroblast population emerges as a key determinant of fibrotic outcomes to biomaterials.

Fibrosis-associated fibroblasts have been identified across various fibrotic disorders, but not in the context of biomaterials, fibrotic encapsulation, and the foreign body response. In other fibrotic disorders, a fibroblast subpopulation defined by Thy-1 loss is strongly correlated with fibrosis yet we do not know what promotes Thy-1 loss. We have previously shown that Thy-1 is an integrin regulator enabling normal fibroblast mechanosensing, and here, leveraging nonfibrotic microporous annealed particle (MAP) hydrogels versus classical fibrotic bulk hydrogels, we demonstrate that mice mount a fibrotic response to MAP gels that includes inflammatory signaling.

Conjugation of IL-33 to Microporous Annealed Particle Scaffolds Enhances Type 2-Like Immune Responses In Vitro and In Vivo.

The inflammatory foreign body response (FBR) is the main driver of biomaterial implant failure. Current strategies to mitigate the onset of a FBR include modification of the implant surface, release of anti-inflammatory drugs, and cell-scale implant porosity. The microporous annealed particle (MAP) scaffold platform is an injectable, porous biomaterial composed of individual microgels, which are annealed in situ to provide a structurally stable scaffold with cell-scale microporosity.

Microporous Annealed Particle (MAP) Scaffold Pore Size Influences Mesenchymal Stem Cell Metabolism and Proliferation Without Changing CD73, CD90, and CD105 Expression Over Two Weeks.

Scaffold pore architecture is shown to influence stem cell fate through various avenues. It is demonstrated that microporous annealed particle (MAP) microgel diameter can be tuned to control scaffold pore size and, in turn, modulate mesenchymal stem cell (MSC) survivability, proliferation, metabolism, and migration, thereby enhancing bioactivity and guiding future applications of MAP for regenerative medicine.

De novo tissue formation using custom microporous annealed particle hydrogel provides long-term vocal fold augmentation.

Biomaterial-enabled de novo formation of non-fibrotic tissue in situ would provide an important tool to physicians. One example application, glottic insufficiency, is a debilitating laryngeal disorder wherein vocal folds do not fully close, resulting in difficulty speaking and swallowing. Preferred management of glottic insufficiency includes bulking of vocal folds via injectable fillers, however, the current options have associated drawbacks including inflammation, accelerated resorption, and foreign body response.

Microfluidic Synthesis of Microgel Building Blocks for Microporous Annealed Particle Scaffold.

The microporous annealed particle (MAP) scaffold platform is a subclass of granular hydrogels. It is composed of an injectable slurry of microgels that can form a structurally stable scaffold with cell-scale porosity in situ following a secondary light-based chemical crosslinking step (i.e.

In silico optimization of heparin microislands in microporous annealed particle hydrogel for endothelial cell migration.

Biomaterials capable of generating growth factor gradients have shown success in guiding tissue regeneration, as growth factor gradients are a physiologic driver of cell migration. Of particular importance, a focus on promoting endothelial cell migration is vital to angiogenesis and new tissue formation. Microporous Annealed Particle (MAP) scaffolds represent a unique niche in the field of regenerative biomaterials research as an injectable biomaterial with an open porosity that allows cells to freely migrate independent of material degradation.

Selective and Improved Photoannealing of Microporous Annealed Particle (MAP) Scaffolds.

Microporous annealed particle (MAP) scaffolds consist of a slurry of hydrogel microspheres that undergo annealing to form a solid scaffold. MAP scaffolds have contained functional groups with dual abilities to participate in Michael-type addition (gelation) and radical polymerization (photoannealing). Functional groups with efficient Michael-type additions react with thiols and amines under physiological conditions, limiting usage for therapeutic delivery.

Activating an adaptive immune response from a hydrogel scaffold imparts regenerative wound healing.

Microporous annealed particle (MAP) scaffolds are flowable, in situ crosslinked, microporous scaffolds composed of microgel building blocks and were previously shown to accelerate wound healing. To promote more extensive tissue ingrowth before scaffold degradation, we aimed to slow MAP degradation by switching the chirality of the crosslinking peptides from L- to D-amino acids. Unexpectedly, despite showing the predicted slower enzymatic degradation in vitro, D-peptide crosslinked MAP hydrogel (D-MAP) hastened material degradation in vivo and imparted significant tissue regeneration to healed cutaneous wounds, including increased tensile strength and hair neogenesis.

Injectable Microannealed Porous Scaffold for Articular Cartilage Regeneration.

Background: The purpose of this study is to assess the feasibility of a novel microporous annealed particle (MAP) scaffolding hydrogel to enable both articular cartilage and subchondral bone biointegration and chondrocyte regeneration in a rat knee osteochondral defect model.

Methods: An injectable, microporous scaffold was engineered and modified to match the mechanical properties of articular cartilage. Two experimental groups were utilized-negative saline control and MAP gel treatment group.

Development of a microporous annealed particle hydrogel for long-term vocal fold augmentation.

Objectives/hypothesis: The purpose of this study was to develop and provide evidence of a novel permanent injectable biomaterial for vocal fold augmentation with the potential to treat glottic incompetence by evaluating its performance in two animal models.

Study Design: Animal model.

Methods: Microporous annealed particle (MAP) hydrogel was fabricated using a water-in-oil emulsion method and synthetically tuned to match the stiffness modulus of native vocalis muscle.

Enhanced In Vivo Delivery of Stem Cells using Microporous Annealed Particle Scaffolds.

Delivery to the proper tissue compartment is a major obstacle hampering the potential of cellular therapeutics for medical conditions. Delivery of cells within biomaterials may improve localization, but traditional and newer void-forming hydrogels must be made in advance with cells being added into the scaffold during the manufacturing process. Injectable, in situ cross-linking microporous scaffolds are recently developed that demonstrate a remarkable ability to provide a matrix for cellular proliferation and growth in vitro in three dimensions.

Particle Hydrogels Based on Hyaluronic Acid Building Blocks.

The extracellular matrix (ECM) provides tissues with the mechanical support, space, and bioactive signals needed for homeostasis or tissue repair after wounding or disease. Hydrogel based scaffolds that can match the bulk mechanical properties of the target tissue have been extensively explored as ECM mimics. Although the addition of microporosity to hydrogel scaffolds has been shown to enhance cell/tissue-material integration, the introduction of microporosity often involves harsh chemical methods, which limit bioactive signal incorporation and injectability.

Accelerated wound healing by injectable microporous gel scaffolds assembled from annealed building blocks.

Injectable hydrogels can provide a scaffold for in situ tissue regrowth and regeneration, yet gel degradation before tissue reformation limits the gels' ability to provide physical support. Here, we show that this shortcoming can be circumvented through an injectable, interconnected microporous gel scaffold assembled from annealed microgel building blocks whose chemical and physical properties can be tailored by microfluidic fabrication. In vitro, cells incorporated during scaffold formation proliferated and formed extensive three-dimensional networks within 48 h.

Hybrid photopatterned enzymatic reaction (HyPER) for in situ cell manipulation.

The ability to design artificial extracellular matrices as cell-instructive scaffolds has opened the door to technologies capable of studying the fate of cells in vitro and to guiding tissue repair in vivo. One main component of the design of artificial extracellular matrices is the incorporation of biochemical cues to guide cell phenotype and multicellular organization. The extracellular matrix (ECM) is composed of a heterogeneous mixture of proteins that present a variety of spatially discrete signals to residing cell populations.

Steric effects in peptide and protein exchange with activated disulfides.

Disulfide exchange is an important bioconjugation tool, enabling chemical modification of peptides and proteins containing free cysteines. We previously reported the synthesis of a macromer bearing an activated disulfide and its incorporation into hydrogels. Despite their ability to diffuse freely into hydrogels, larger proteins were unable to undergo in-gel disulfide exchange.

Synthesis of photodegradable macromers for conjugation and release of bioactive molecules.

Hydrogel scaffolds are used in biomedicine to study cell differentiation and tissue evolution, where it is critical to control the delivery of chemical cues both spatially and temporally. While large molecules can be physically entrapped in a hydrogel, moderate molecular weight therapeutics must be tethered to the hydrogel network through a labile linkage to allow controlled release. We synthesized and characterized a library of polymerizable ortho-nitrobenzyl (o-NB) macromers with different functionalities at the benzylic position (alcohol, amine, BOC-amine, halide, acrylate, carboxylic acid, activated disulfide, N-hydroxysuccinyl ester, biotin).

Photo-selective delivery of model therapeutics from hydrogels.

Hydrogels are commonly used in biomedical applications to sequester and release therapeutics. Covalently tethering therapeutic agents to a hydrogel through a degradable linkage allows their controlled release, but temporally separating the release of multiple therapeutics from a single hydrogel remains a major challenge. In this report, we use of a series of photodegradable -nitrobenzyl (-NB) groups with varying structures to link model therapeutic agents (fluorescein, rhodamine and aminomethylcoumarin acetate) to poly(ethylene glycol) macromers.

Photodegradable macromers and hydrogels for live cell encapsulation and release.

Hydrogel scaffolds are commonly used as 3D carriers for cells because their properties can be tailored to match natural extracellular matrix. Hydrogels may be used in tissue engineering and regenerative medicine to deliver therapeutic cells to injured or diseased tissue through controlled degradation. Hydrolysis and enzymolysis are the two most common mechanisms employed for hydrogel degradation, but neither allows sequential or staged release of cells.

Photodegradation as a mechanism for controlled drug delivery.

A drug-releasing model compound based on photosensitive acrylated ortho-nitrobenzylether (o-NBE) moiety and fluorescein was synthesized to demonstrate photolysis as a mechanism for drug release. Release of this model compound from a hydrogel network can be controlled with light intensity (5-20 mW/cm(2)), exposure duration (0-20 min) and wavelength (365, 405, 436 nm). Due to the high molar absorptivity of the compound (5,984 M(-1) cm(-1)), light attenuation is significant in this system.

Significant uncertainty is common in nature.

In animals' natural lives, uncertainty is normal; and certainty, exceptional. Evaluating ambiguous information is essential for survival: Does what is seen, heard, or smelled mean danger? Does that gesture mean aggression or fear? Is he confident or uncertain? If they are conscious of anything, the content of animals' awareness probably includes crucial uncertainties, both their own and those of others.

New evidence of animal consciousness.

This paper reviews evidence that increases the probability that many animals experience at least simple levels of consciousness. First, the search for neural correlates of consciousness has not found any consciousness-producing structure or process that is limited to human brains. Second, appropriate responses to novel challenges for which the animal has not been prepared by genetic programming or previous experience provide suggestive evidence of animal consciousness because such versatility is most effectively organized by conscious thinking.