Alginate Sulfate–Nanocellulose Bioinks for Cartilage Bioprinting Applications

Abstract

One of the challenges of bioprinting is to identify bioinks which support cell growth, tissue maturation, and ultimately the formation of functional grafts for use in regenerative medicine. The influence of this new biofabrication technology on biology of living cells, however, is still being evaluated. Recently we have identified a mitogenic hydrogel system based on alginate sulfate which potently supports chondrocyte phenotype, but is not printable due to its rheological properties (no yield point). To convert alginate sulfate to a printable bioink, it was combined with nanocellulose, which has been shown to possess very good printability. The alginate sulfate/nanocellulose ink showed good printing properties and the non-printed bioink material promoted cell spreading, proliferation, and collagen II synthesis by the encapsulated cells. When the bioink was printed, the biological performance of the cells was highly dependent on the nozzle geometry. Cell spreading properties were maintained with the lowest extrusion pressure and shear stress. However, extruding the alginate sulfate/nanocellulose bioink and chondrocytes significantly compromised cell proliferation, particularly when using small diameter nozzles and valves.

Applications of Alginate-Based Bioinks in 3D Bioprinting

“…This mix was finally cured by UV irradiation. In order to make alginate sulfate printable for cartilage tissue engineering applications, it was combined with nanocellulose by Müller et al [46], exhibiting good printing properties. Nonetheless, when this bioink was extruded, the chondrocyte cell proliferation was seriously affected when using small-diameter nozzles and valves which limit its application to a low-resolution printing.…”

Structured Macroporous Hydrogels: Progress, Challenges, and Opportunities

“…[178] The use of in situ gelation chemistries in 3D printing is still in its infancy, aside from the ionotropic alginate-calcium gelation mechanism that forms the basis of most existing hydrogel 3D printers. [139,179,180] Thermogelation by printing on a heated platform (e.g., methacrylamide-PEG-based triblock copolymer hydrogels [181] ) or a cooled platform (e.g., sodium alginate/ gelatin [92] ) has also been demonstrated, although suffers from drawbacks associated with the stability of the resulting structures outside of the controlled temperature environment, the capacity to print thicker structures further away from the temperature-controlled base, and a lack of flexibility regarding the hydrogel components in order to facilitate the required thermogelation. Combinations of physical gelation with UV photopolymerization have also been demonstrated.…”

Repair of Damaged Articular Cartilage: Current Approaches and Future Directions

“…Natural polymers are limited to alginate [98,99,100,101], gelatin [102,103], agarose [104,105], hyaluronic acid [106], fibrin, and collagen [107]. The synthetic group is more diverse and generally includes poly( ɛ -caprolactone) [102,108], poly( l -lactic acid) [109,110], poly(lactic-co-glycolic acid) [111,112], poly(vinyl alcohol) [113], polyethylene glycol [114], pluronics [115], polyurethane [116], and self-assembling peptides [104].…”