Indirect 3D bioprinting and characterization of alginate scaffolds for potential nerve tissue engineering applications

Abstract

Saman Naghieh) and xbc719@mail.usask.ca (Xiongbiao Chen). AbstractLow-concentration hydrogels have favorable properties for many cell functions in tissue engineering but are considerably limited from a scaffold fabrication point of view due to poor three-dimensional (3D) printability. Here, we developed an indirect-bioprinting process for alginate scaffolds and characterized the potential of these scaffolds for nerve tissue engineering applications. The indirect-bioprinting process involves (1) printing a sacrificial framework from gelatin, (2) impregnating the framework with low-concentration alginate, and (3) removing the gelatin framework by an incubation process, thus forming low-concentration alginate scaffolds. The scaffolds were characterized by compression testing, swelling, degradation, and morphological and biological assessment of incorporated or seeded Schwann cells. For comparison, varying concentrations of alginate scaffolds (from 0.5 to 3%) were fabricated and sterilized using either ultraviolet light or ethanol. Results indicated that scaffolds can be fabricated using the indirect-bioprinting process, wherein the scaffold properties are affected by 5 the concentration of alginate and sterilization technique used. These factors provide effective means of regulating the properties of scaffolds fabricated using the indirect-bioprinting process.Cell-incorporated scaffolds demonstrated better cell viability than bulk gels. In addition, scaffolds showed better cell functionality when fabricated with a lower concentration of alginate compared to a higher concentration. The indirect-bioprinting process that we implemented could be extended to other types of low-concentration hydrogels to address the tradeoffs between printability and properties for favorable cell functions.

Printability of 3D Printed Hydrogel Scaffolds: Influence of Hydrogel Composition and Printing Parameters

“…The pure alginate samples (Group 1), Group G, Group 3, and Group 4 showed 32.53%, 13.33%, 40.00%, and 19.70% degradation, respectively, over time incubated in PBS. PBS has been used widely to evaluate the degradation rate of scaffolds, as reported in References [11,[28][29][30]. Notably, as future work, other solutions such as fetal bovine serum and penicillin-streptomycin contained medium can be used to check the degradation rate of scaffolds.…”

“…It means that factors affecting printability such as pressure can directly affect cell viability and that is why it is important to consider cell viability. Readers are encouraged to check a recent study on printability and cell viability for more information [29].…”

3D Printing and Bioprinting Nerve Conduits for Neural Tissue Engineering

“…Compared with implanted collagen sponge and fibrin glue, nerve regeneration in alginate hydrogel is much better. Saman et al [73] used indirect 3D printing to prepare a sodium alginate hydrogel scaffold that embeds Schwann cells at the expense of gelatin frames. The results of the study showed that Schwann cells in this scaffold were more viable than those in bulk gel.…”

Advancements in Canadian Biomaterials Research in Neurotraumatic Diagnosis and Therapies

“…Scaffolds with living cells and/or bioactive molecules can be fabricated using 3D bioprinting techniques, where a scaffold is fabricated by laying down threads or fibers of bioink, i.e., the mixture of hydrogel, living cells, and/or bioactive molecules, in a controllable layer-by-layer manner [46]. Specifically, Chen et al have illustrated the feasibility of bioprinting scaffolds from alginate hydrogel or a composite hydrogel mixture of alginate and hyaluronic acid, with both controlled microstructure and controlled distribution of living Schwann cells for use in peripheral nerve repair applications [26,[47][48][49][50][51].…”