Abstract
Introduction: Alginate, a linear polysaccharide from seaweed, is used both in food and in biomedical applications. The low toxicity and immunogenicity together with the ability to form hydrogels at physiological conditions makes them attractive scaffolds in tissue engineering. In this first part of the 3DLife project, we have tailored alginate gel kinetics, mechanical properties and gel dissolution to be relevant for soft tissue engineering, 96-wellplate format and robotic handling.
Methods: Alginate gelation kinetics and mechanical properties was controlled by using the slowly hydrolysing glucono-δ-lactone (GDL) together with CaCO3 and citrate buffer. The gelation was followed on a Kinexus Rheometer and gel elasticity measured as storage modulus (G´). Fibroblasts (IMR90) was mixed with citrate buffer, alginate and CaCO3 before the addition of GDL and culture media was added 2 hrs after gelation. Different cell concentrations, alginate concentrations and viability assays were evaluated over a culture period for 72 hours.
Results and Discussion: Alginate hydrogel mechanical properties (G´) was controlled by increasing alginate concentrations and CaCO3 and GDL accordingly (Figure 1A). This gives plateau values of storage modulus of 100 and 800 Pa for 0.5% alginate and 1.0% alginate, respectively, which is within the relevant range of soft tissue previously shown for gels of PEG and hyaluronic acid. Cell encapsulation and culture conditions were optimised for robotic handling and culture in 96-wellplate format. Preliminary results show cells with different morphology in the hydrogels of 0.5% and the 1.0% alginate, indicating sensitivity towards mechanical properties (Figure 1B and C). The hydrogels could easily be dissolved within 30 to 140 seconds and cell retrieved by adding a calcium-chelating buffer. This is important for the further and detailed analyses of the cell transcriptome under tailored conditions in their microenvironment.
Methods: Alginate gelation kinetics and mechanical properties was controlled by using the slowly hydrolysing glucono-δ-lactone (GDL) together with CaCO3 and citrate buffer. The gelation was followed on a Kinexus Rheometer and gel elasticity measured as storage modulus (G´). Fibroblasts (IMR90) was mixed with citrate buffer, alginate and CaCO3 before the addition of GDL and culture media was added 2 hrs after gelation. Different cell concentrations, alginate concentrations and viability assays were evaluated over a culture period for 72 hours.
Results and Discussion: Alginate hydrogel mechanical properties (G´) was controlled by increasing alginate concentrations and CaCO3 and GDL accordingly (Figure 1A). This gives plateau values of storage modulus of 100 and 800 Pa for 0.5% alginate and 1.0% alginate, respectively, which is within the relevant range of soft tissue previously shown for gels of PEG and hyaluronic acid. Cell encapsulation and culture conditions were optimised for robotic handling and culture in 96-wellplate format. Preliminary results show cells with different morphology in the hydrogels of 0.5% and the 1.0% alginate, indicating sensitivity towards mechanical properties (Figure 1B and C). The hydrogels could easily be dissolved within 30 to 140 seconds and cell retrieved by adding a calcium-chelating buffer. This is important for the further and detailed analyses of the cell transcriptome under tailored conditions in their microenvironment.
