Introduction: Hydrogels are three dimensional (3D) structures in which cells can be encapsulated in an environment which is similar to the extracellular matrix. Suitable hydrogel systems for Tissue Engineering should be biocompatible, biodegradable and the mechanical properties should match those of the desired tissue. With the 3D printing of hydrogel solutions constructs with defined pore sizes can be obtained. Hence the printing of cell-seeded hydrogels enables a higher variability in the field of Tissue Engineering[1]. The focus of our work is on printing of hydrogel solutions based on polyglycidols and hyaluronic acid. This leads to a chemical cross-linked hydrogel construct with defined geometry.
Materials and Methods: P(AGE-co-G) was synthesized in bulk according to[2] with addition of AGE monomer for the co-polymerisation. P(AGE-co-G) was afterwards converted to PG-SH and different degrees of functionalization were achieved. To receive the desired hydrogel, thiol-ene click reaction was used for cross-linking. The photochemical introduced reaction (Irgacure 2959, 10 min at 365 nm) occurs between P(AGE-co-G) and PG-SH. Addition of native hyaluronic acid to the hydrogel solution was used to tailor rheological properties of the formulation for printability using dispense plotting.
Results and Discussion: After synthesis of the scaffold polymers, optimal polymer ratios and reaction conditions were evaluated. Furthermore precursor solutions were optimized in viscosity by adding additional non-modified hyaluronic acid to achieve printability. Afterwards first cell encapsulation studies were carried out.
Conclusion: By combination of the hydrogel system with unmodified hyaluronic acid the solution is printable and hence hierarchical constructs could be obtained. Next steps will focus on optimizing the printing parameters and furthermore on printing of cell-laden hydrogels.
We thank the European Union’s Seventh Framework Programme (FP7/2007-2013) for funding under grant agreement no. 309962 (project HydroZONES)
References:
[1] J. Malda, J. Visser, F. P. Melchels, T. Jüngst, W. E. Hennink, W. J. A. Dhert, J. Groll, D. W. Hutmacher, Adv. Mater. 2013, 25, 5011-5028.
[2] J. Groll, S. Singh, K. Albrecht, M. Moeller, Journal of Polymer Science Part A: Polymer Chemistry 2009, 47, 5543.