Printing cell-laden gelatin constructs by free-form fabrication and enzymatic protein crosslinking

Abstract

Considerable interest has arisen in precision fabrication of cell bearing scaffolds and structures by free form fabrication. Gelatin is an ideal material for creating cell entrapping constructs, yet its application in free form fabrication remains challenging. We demonstrate the use of gelatin, crosslinked with microbial transglutaminase (mTgase), as a material to print cell bearing hydrogels for both 2-dimensional (2-D) precision patterns and 3-dimensional (3-D) constructs. The precision patterning was attained with 3 % gelatin and 2 % high molecular weight poly (ethylene oxide) (PEO) whereas 3-D constructs were obtained using a 5 % gelatin solution. These hydrogels, referred to as “bioinks” supported entrapped cell growth, allowing cell spreading and proliferation for both HEK293 cells and Human Umbilical Vein Endothelial Cells (HUVECs). These bioinks were shown to be dispensable by robotic precision, forming patterns and constructs that were insoluble and of suitable stiffness to endure post gelation handling. The two bioinks were further characterized for fabrication parameters and mechanical properties.Electronic supplementary materialThe online version of this article (doi:10.1007/s10544-014-9915-8) contains supplementary material, which is available to authorized users.

Synthesis and Characterization of Types A and B Gelatin Methacryloyl for Bioink Applications

“…An ink material can become a scaffold after a certain treatment such as heat, ions, enzymes and light. Examples of typical bioink materials are alginate [20], gelatin [21], and gelatin methacryloyl [16,22,23]. Ideal bioinks have some important characteristics such as low cost, printability, cell compatibility and cell-specific functionality [10].…”

“…The research conducted by Billiet et al in 2014 showed that the 3D printed GelMA scaffold had excellent cell viability and scaffold stability for 14 days, indicating that GelMA could have great potential as a bioink for 3D bioprinting [16]. Most of the existing research studies carried out on GelMA focused on rheological studies [21], printing parameters [16] and cell viability [16,21,22]. …”

Mechanically Tunable Bioink for 3D Bioprinting of Human Cells

“…[8] However, the advantage of direct fabrication techniques, especially of 3D bioprinting, is its ability to generate constructs with spatially defined cell and material composition. Moreover, biomaterials that are conventionally used in cell culture such as alginate, [9] Pluronic, [10] gelatin, [11] nanocellulose, [12] self-assembling peptides, [13] and agarose [14] are highly advantageous for direct cell printing as they are soluble in water and hence can be formulated as a cell carrier. There has been extensive effort to build on and improve the properties of watersoluble polymers as bioinks.…”

A novel 3D printing method for cell alignment and differentiation

“…Its application has given tissue engineers a method for cellular deposition with control up to the micrometer level [1,2] . Additionally, cell adhering surfaces can be modified to influence the orientation and morphology of the attached cells [3] .…”

“…Cells can be directly seeded onto a patterned surface; however, when more than 1 cell lines are seeded and their spatial distribution is important, then the deposition of the cells require more accurate control. We have previously demonstrated how cells can be bioprinted with relative precision using robotic dispensing system, delivering viable cells within a hydrogel bioink [1] . When cell-containing growth medium is deposited, the printed trace spreads out due to its low viscosity (at approximately 0.94 cP) [22] .…”