“…Limited range of elasticity (100 Pa -2 kPa) adjustable by varying pH, gelation temperature, and collagen concentration [330] Increase of stiffness by crosslinking, [200] ultracentrifugation, [201] gel compression, [202] evaporating the solvent [203] or chemical modification [204] Mild stiffness adjustment via transglutaminase-mediated crosslinking [198] and MMC [207c] Suitable for embedding cells Self-assembling Smooth muscle cells, [184] MSC differentiation, [185] adipocytes culture and differentiation, [186] epithelial growth and branching of several organs, 332] tumor modeling, [191][192][193][194] angiogenesis [196,197,333] Human and murine intestinal organoid cultures [209,210] Murine stomach organoid, [209d] modeling PKD cystogenesis [211] Biopolymer [339] Mimics the mechanical properties of neonatal hearts Electrostatically complexes positively charged growth factors (e.g., bFGF, SDF-1, VEGF) [340] Contains target sequences of matrix metalloproteinases (MMP) rendering it degradable Cardiac grafts based on fetal rat ventricular muscle, [214] angiogenesis, [215a] colonoids, [223] cardiac fibrosis [339] Biopolymer-based hydrogels: Hyaluronic acid From rooster combs, shark skin, bovine eyeballs, or human umbilical cords [335] Animal-free produc- BMP, [343] NGF, SDF-1α) [342] Allows for hyaluronidases-mediated remodeling [267] or for degradation by reactive oxygen species [346] Engineered MMP degradation sites allow further degradation Undifferentiated hESC growth, [344] bone and cartilage engineering, [345] neural differentiation,…”