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Creators/Authors contains: "Caprio, Nikolas Di"

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  1. Abstract

    Many cell types require direct cell–cell interactions for differentiation and function; yet, this can be challenging to incorporate into 3‐dimensional (3D) structures for the engineering of tissues. Here, a new approach is introduced that combines aggregates of cells (spheroids) with similarly‐sized hydrogel particles (microgels) to form granular composites that are injectable, undergo interparticle crosslinking via light for initial stabilization, permit cell–cell contacts for cell signaling, and allow spheroid fusion and growth. One area where this is important is in cartilage tissue engineering, as cell–cell contacts are crucial to chondrogenesis and are missing in many tissue engineering approaches. To address this, granular composites are developed from adult porcine mesenchymal stromal cell (MSC) spheroids and hyaluronic acid microgels and simulations and experimental analyses are used to establish the importance of initial MSC spheroid to microgel volume ratios to balance mechanical support with tissue growth. Long‐term chondrogenic cultures of granular composites produce engineered cartilage tissue with extensive matrix deposition and mechanical properties within the range of cartilage, as well as integration with native tissue. Altogether, a new strategy of injectable granular composites is developed that leverages the benefits of cell–cell interactions through spheroids with the mechanical stabilization afforded with engineered hydrogels.

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  2. Abstract

    The fabrication of perfusable hydrogels is crucial for recreating in vitro microphysiological environments. Existing strategies to fabricate complex microchannels in hydrogels involve sophisticated equipment/techniques. A cost‐effective, facile, versatile, and ultra‐fast methodology is reported to fabricate perfusable microchannels of complex shapes in photopolymerizable hydrogels without the need of specialized equipment or sophisticated protocols. The methodology utilizes one‐step ultraviolet (UV) light‐triggered cross‐linking and a photomask printed on inexpensive transparent films to photopattern PEG‐norbornene hydrogels. Complex and intricate patterns with high resolution, including perfusable microchannels, can be fabricated in <1 s. The perfusable hydrogel is integrated into a custom‐made microfluidic device that permits connection to external pump systems, allowing continuous fluid perfusion into the microchannels. Under dynamic culture, human endothelial cells form a functional and confluent endothelial monolayer that remains viable for at least 7 days and respond to inflammatory stimuli. Finally, approach to photopattern norbornene hyaluronic acid hydrogels is adapted, highlighting the versatility of the technique. This study presents an innovative strategy to simplify and reduce the cost of biofabrication techniques for developing functional in vitro models using perfusable three‐dimensional (3D) hydrogels. The approach offers a novel solution to overcome the complexities associated with existing methods, allowing engineering advanced in vitro microphysiological environments.

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