A Psychrophilic GelMA: Breaking Technical and Immunological Barriers for Multimaterial High-Resolution 3D Bioprinting.

The increasing demand for tissue replacement has encouraged scientists worldwide to focus on developing new biofabrication technologies. Multimaterials/cells printed with stringent resolutions are necessary to address the high complexity of tissues. Advanced inkjet 3D printing can use multimaterials and attain high resolution and complexity of printed structures. However, a decisive yet limiting aspect of translational 3D bioprinting is selecting the befitting material to be used as bioink; there is a complete lack of cytoactive bioinks with adequate rheological, mechanical, and reactive properties. This work strives to achieve the right balance between resolution and cell support through methacrylamide functionalization of a psychrophilic gelatin and new fluorosurfactants used to engineer a photo-cross-linkable and immunoevasive bioink. The syntonized parameters following optimal formulation conditions allow proficient printability in a PolyJet 3D printer comparable in resolution to a commercial synthetic ink (∼150 µm). The bioink formulation achieved the desired viability (∼80%) and proliferation of co-printed cells while demonstrating in vivo immune tolerance of printed structures. The practical usage of existing high-resolution 3D printing systems using a novel bioink is shown here, allowing 3D bioprinted structures with potentially unprecedented complexity.

Cold-adaptation of a methacrylamide gelatin towards the expansion of the biomaterial toolbox for specialized functionalities in tissue engineering.

Tissue regeneration is witnessing a significant surge in advanced medicine. It requires the interaction of scaffolds with different cell types for efficient tissue formation post-implantation. The presence of tissue subtypes in more complex organs demands the co-existence of different biomaterials showing different hydrolysis rate for specialized cell-dependent remodeling. To expand the available toolbox of biomaterials with sufficient mechanical strength and variable rate of enzymatic degradation, a cold-adapted methacrylamide gelatin was developed from salmon skin. Compared with mammalian methacrylamide gelatin (GelMA), hydrogels derived from salmon GelMA displayed similar mechanical properties than the former. Nevertheless, salmon gelatin and salmon GelMA-derived hydrogels presented characteristics common of cold-adaptation, such as reduced activation energy for collagenase, increased enzymatic hydrolysis turnover of hydrogels, increased interconnected polypeptides molecular mobility and lower physical gelation capability. These properties resulted in increased cell-remodeling rate in vitro and in vivo, proving the potential and biological tolerance of this mechanically adequate cold-adapted biomaterial as alternative scaffold subtypes with improved cell invasion and tissue fusion capacity.

Improving myoblast differentiation on electrospun poly(ε-caprolactone) scaffolds.

Polymer scaffolds are used as an alternative to support tissue regeneration when it does not occur on its own. Cell response on polymer scaffolds is determined by factors such as polymer composition, topology, and the presence of other molecules. We evaluated the cellular response of murine skeletal muscle myoblasts on aligned or unaligned fibers obtained by electrospinning poly(ε-caprolactone) (PCL), and blends with poly(lactic-co-glycolic acid) (PLGA) or decorin, a proteoglycan known to regulate myogenesis. The results showed that aligned PCL fibers with higher content of PLGA promote cell growth and improve the quality of differentiation with PLGA scaffolds having the highest confluence at over 68% of coverage per field of view for myoblasts and more than 7% of coverage for myotubes. At the same time, the addition of decorin greatly improves the quantity and quality of differentiated cells in terms of cell fusion, myotube length and thickness, being 71, 10, and 51% greater than without the protein, respectively. Interestingly, our results suggest that at certain concentrations, the effect of decorin on myoblast differentiation exceeds the topological effect of fiber alignment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2241-2251, 2017.