Manipulation of blended hydrogel matrix for 3D cell culture

摘要

Introduction: Hydrogels are tools that have been used to study cell behavior in a three dimensional microenvironment. The nature of polymer network that forms the hydrogel matrix greatly influences the morphology and behavior of cells. The cells encapsulated in an inert restrictive matrix show spheroidal type of growth while those in a degradable matrix show spreading and migration. Moreover, we have demonstrated this change in behavior of cells by just switching concentrations in a blended matrix system. In this study, we have used poly (ethylene glycol) diacrylate (PEGDA) and gelatin methacrylate (GELMA) to make a blended hydrogel system and have shown the influence of ratio of the two components on the morphology and behavior of tumor cells and endothelial cells encapsulated in the hydrogel. Materials and Methods: PEGDA and GELMA were synthesized as previously reported in literature. Blended hydrogel matrices were prepared by mixing PEGDA and GELMA at different concentrations and subsequently photopolymerizing the hydrogeis under ultraviolet (UV) illumination using Irgacure 2595 (Sigma Aldrich) as the photoinitiator. MDA-MB-231 cells were grown under standard cell culture conditions using DMEM supplemented with 10% FBS and antibiotics. Cells were suspended in the polymer network prior to UV illumination so that subsequent formation of hydrogel led to encapsulation of cells. Pore size was determined using cryo-SEM and storage modulus was studied using rheometer having parallel plate geometry. The viability and proliferation of cells in the gel was studied by live/dead staining and Alamar blue viability assay. Results: The results from this study show that MDA-MB-231 breast cancer cells encapsulated in the blended hydrogel of PEGDA and GELMA (10:1 w/v %), wherein PEGDA is the major component of the matrix, form spheroids. Interestingly, when we invert the ratio of PEGDA and GELMA in the hydrogel network such that GELMA is the major component (5:1 w/v %), we observe cells spreading and migrating within the matrix. The growth of spheroids and the spreading of cells in both the matrices are influenced by the stiffness of the matrix. There is no significant difference in the pore sizes of the two matrix systems while their mechanical properties and degradability is significantly different. We further tune the mechanical properties of GELMA:PEGDA system by changing the molecular weight of PEGDA. We have also used the GELMA:PEGDA hydrogel to study angiogenesis using chick aortic arch assay and have found sprouting of endothelial cells to be influenced by the stiffness of GELMA:PEGDA system. Conclusion: We have developed a blended hydrogel matrix system using PEGDA and GELMA and have characterized the mechanical properties, degradability and pore size of the matrix. We have shown that changing the ratio or composition of PEGDA and GELMA influences the cellular morphology and behavior of MDA-MB-231 breast cancer cells and chick aortic endothelial cells within the matrix.