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    Enzyme-mediated Alleviation of Peroxide Toxicity in Self-oxygenating Biomaterials
    (2022) Willemen, Niels G. A.; Hassan, Shabir; Gurian, Melvin; Jasso-Salazar, Maria Fernanda; Fan, Kai; Wang, Haihang; Becker, Malin; Allijn, Iris E.; Bal Öztürk, Ayça; Leijten, Jeroen; Shin, Su Ryon
    Oxygen releasing biomaterials can facilitate the survival of living implants by creating environments with a viable oxygen level. Hydrophobic oxygen generating microparticles (HOGMPs) encapsulated calcium peroxide (CPO) have recently been used in tissue engineering to release physiologically relevant amounts of oxygen for several weeks. However, generating oxygen using CPO is mediated via the generation of toxic levels of hydrogen peroxide (H2 O2 ). The incorporation of antioxidants, such as catalases, could potentially reduce H2 O2 levels. However, the formulation in which catalases can most effectively scavenge H2 O2 within oxygen generating biomaterials has remained unexplored. In this study, four distinct catalase incorporation methods were compared based on their ability to decrease H2 O2 levels. Specifically, catalase was incorporated within HOGMPs, or absorbed onto HOGMPs, or freely laden into the hydrogel entrapping HOGMPs and compared with control without catalase. Supplementation of free catalase in an HOGMP-laden hydrogel significantly decreased H2 O2 levels reflecting a higher cellular viability and metabolic activity of all the groups. An HOGMP/catalase-laden hydrogel precursor solution containing cells was used as an oxygenating bioink allowing improved viability of printed constructs under severe hypoxic conditions. The combination of HOGMPs with a catalase-laden hydrogel has the potential to decrease peroxide toxicity of oxygen generating tissues. This article is protected by copyright. All rights reserved.
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    Hybrid extracellular vesicles-liposome incorporated advanced bioink to deliver microRNA
    (IOP Publishing, 2022) Elkhoury, Kamil; Chen, Mo; Koçak, Polen; Enciso-Martínez, Eduardo; Bassous, Nicole Joy; Chul Lee, Myung; Byambaa, Batzaya; Rezaei, Zahra; Li, Yang; Ubina López , María Elizabeth; Gurian, Melvin; Sobahi, Nebras; Asif Hussain, Mohammad; Sanchez-Gonzalez, Laura; Leijten, Jeroen; Hassan, Shabir; Arab-Tehrany, Elmira; Ellis Ward, Jennifer; Shin, Su Ryon
    In additive manufacturing, bioink formulations govern strategies to engineer 3D living tissues that mimic the complex architectures and functions of native tissues for successful tissue regeneration. Conventional 3D-printed tissues are limited in their ability to alter the fate of laden cells. Specifically, the efficient delivery of gene expression regulators (i.e. microRNAs (miRNAs)) to cells in bioprinted tissues has remained largely elusive. In this study, we explored the inclusion of extracellular vesicles (EVs), naturally occurring nanovesicles (NVs), into bioinks to resolve this challenge. EVs show excellent biocompatibility, rapid endocytosis, and low immunogenicity, which lead to the efficient delivery of miRNAs without measurable cytotoxicity. EVs were fused with liposomes to prolong and control their release by altering their physical interaction with the bioink. Hybrid EVs-liposome (hEL) NVs were embedded in gelatin-based hydrogels to create bioinks that could efficiently encapsulate and deliver miRNAs at the target site in a controlled and sustained manner. The regulation of cells' gene expression in a 3D bioprinted matrix was achieved using the hELs-laden bioink as a precursor for excellent shape fidelity and high cell viability constructs. Novel regulatory factors-loaded bioinks will expedite the translation of new bioprinting applications in the tissue engineering field.