RESUMO
This review evaluates hydrogel-forming polymers that are suitable for soft tissue engineering with a focus on materials that can be fabricated using additive manufacturing (3D-printing). An overview of the specific material requirements for hydrogel-based tissue engineering constructs is presented. This is followed by an explanation of the various hydrogel-forming polymer classes that includes a detailed examination of material properties that are critical for extrusion printing. Specifically, mechanisms for hydrogel formation, degradation, and biological response, activity and compatibility are explored. A discussion of extrusion printing strategies for printable hydrogel-forming polymers is then presented in conjunction with a list of considerations to guide future tissue engineering developments.
RESUMO
Gellan gum (GG) is an anionic polysaccharide with potential as a biopolymer for additive manufacturing (3D-bioprinting) and tissue engineering. Previous studies have shown GG to be highly cytocompatible, but lacking specific attachment sites required for anchorage-dependent cells. In this work, we modify purified-GG polymer with a short peptide containing the arginine-glycine-aspartic acid (RGD) sequence that is known to enhance integrin-mediated cell attachment. Radiolabelling of the peptide was used in optimisation of the conjugation procedure to achieve an overall efficiency of 40%. The purification of divalent cations from commercial GG samples was found to be critical for successful conjugation. Rheological studies revealed that the peptide coupling did not prevent gelation behaviour. C2C12 cells showed improved attachment on the surface of and encapsulated within RGD-GG hydrogels, differentiating to multinucleated myofibers after 5-7 days. PC12 cells showed minimal interactions with both GG and RGD-GG, with formation of cell clusters and impedance of terminal differentiation and neurite extension.