Bi-functional oxidized dextran-based hydrogel inducing microtumors: An in vitro three-dimensional lung tumor model for drug toxicity assays.

Cancer is a serious death causing disease having 8.2 million deaths in 2012. In the last decade, only about 10% of chemotherapeutic compounds showed productivity in drug screening. Two-dimensional culture assays are the most common in vitro drug screening models, which do not precisely model the in vivo condition for reliable preclinical drug screening. Three-dimensional scaffold-based cell cultures perhaps mimic tumor microenvironment and recapitulate physiologically more relevant tumor. This study was carried out to develop bi-functional oxidized dextran-based cell instructive hydrogel that provides three-dimensional environment to cancer cells for inducing microtumor. Oxidized dextran was blended with thiolated chitosan to fabricate an in situ self-gelable hydrogel (modified dextran-chitosan) in a one-step process. The hydrogels characterization revealed cross-linked network structure with highly porous structure and water absorption. The modified dextran-chitosan hydrogel showed reduced hydrophobicity and has reduced protein absorption, which resulted in changing the A549 cell adhesiveness, and encouraged them to form microtumor. The cells were proliferated in clusters having spherical morphology with randomly oriented stress fiber and large nucleus. Further microtumors were studied for hypoxia where reactive oxygen species generation demonstrated 15-fold increase as compared to monolayer culture. Drug-sensitivity results showed that microtumors generated on modified dextran-chitosan hydrogel showed resistance to doxorubicin with having 33%-58% increased growth than two-dimensional monolayer model at concentrations of 25-100 µM. In summary, the modified dextran-chitosan scaffold can provide surface chemistry that induces three-dimensional microtumors with physiologically relevant properties to in vivo tumor including growth, morphology, extracellular matrix production, hypoxic phenotype, and drug response. This model can be potentially utilized for drug toxicity studies and cancer disease modeling to understand tumor phenotype and progression.