Synthesis of stiffness‐tunable and cell‐responsive Gelatin–poly(ethylene glycol) hydrogel for three‐dimensional cell encapsulation

Abstract

Biosynthetic poly(ethylene glycol) (PEG)-based hydrogels have been extensively investigated as extracellular matrix (ECM) mimicking gels as they retain the benefits of both ECM (biological cues) and synthetic hydrogels (tunable mechanical properties). In this article, we developed and characterized a new gelatin-PEG (GP) hydrogel that retains the benefits of gelatin and synthetic hydrogels. In this strategy, the thiolation of gelatin was accomplished by reacting with Traut's reagent; the thiolated gelatin was then conjugated to one end of PEG diacrylate (PEGDA) by Michael-type addition reaction. Two kinds of GP precursors, GP30 and GP60, were synthesized by changing the amount of Traut's reagent, while the weight ratio between thiolated-gelatin and PEGDA of GP30 and GP60 was 1.451:1 and 0.785:1, respectively. Finally, neonatal human dermal fibroblasts were encapsulated into the hydrogel by cross-linking the remaining double bonds of precursor under ultraviolet light. These GP hydrogels can encapsulate the fibroblasts in situ with high cell viability. Moreover, the behaviors of cells within the GP hydrogels can be modulated by varying the cross-linking density of GP hydrogel (storage modulus from 40 to 2000 Pa). In particular, this article showed that a minimum amount of cell-binding motifs (gelatin >2.30 wt/vol % and 44.0% dry weight percentage) are required for attachment; and appropriate initial rheological and structural properties (storage modulus <∼100 Pa and mesh size >∼150 nm) can accelerate the attachment of cells and improve cell viability. Hence, this mixed-hydrogel platform allows an easily control hydrogel structure and modulates cell behavior to reconstruct new tissue in the three-dimensional microenvironments. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2401-2411, 2016.

Inclusion of Cross-Linked Elastin in Gelatin/PEG Hydrogels Favourably Influences Fibroblast Phenotype

“…Integra consists of a porous dermal layer fabricated from bovine collagen, chondroitin-6-sulfate, and a temporary silicone layer. Unfortunately, it also suffers from severe wound contraction and excessive scar formation [22,23]. It has been proven that the inclusion of elastin to the dermal substitutes is particularly important in dermal substitutes, as it is a key biological component to impart elastic properties into tissues and suppress adverse reactions during wound healing [24].…”

Generation and manipulation of hydrogel microcapsules by droplet-based microfluidics for mammalian cell culture

“…It usually first disperses cells into precursor solution, followed by the breakup of cell suspension into discrete droplets and the polymerization of the precursor droplets into hydrogel microcapsules 27, 28 . The miniaturized size of microcapsules help avoid problems associated with mass transport due to the enlarged surface-to-volume ratio, allowing for optimum cell metabolism, growth, and functions 29, 30 .In addition, the biocompatible nature of hydrogel matrices can simulate natural ECM with tunable structures and properties to achieve biomimetic cell culture and tissue engineering 31–33 . Besides individual microcapsules, cells or microtissues can also be conveniently encapsulated in continuous microfibers as long as meters by one-phase microfluidics 34, 35 , but their elongated morphology not only imposes severe barriers in cell handling, especially for assembly and injection, but also mostly restricts the cell interaction and tissue formation in one dimension.…”

Advances of Stem Cell-Laden Hydrogels With Biomimetic Microenvironment for Osteochondral Repair

“…In particular, a class of heterodimeric receptors as integrins link the intracellular cytoskeleton to the specific cell-adhesive ligands on ECM proteins (Barczyk et al, 2010). Tripeptide arginineglycine-aspartic acid (RGD) is found in multiple ECM proteins and binds to several different integrin dimers, which facilitates cell spreading and migration (Cao et al, 2016) and has been incorporated into hydrogel systems to construct the adhesion of various cell types (Hersel et al, 2003;Cipriani et al, 2019). Besides, combinations of other ligands with RGD are also necessary to elicit the desired behaviors.…”