Drug diffusion in biomimetic hydrogels: importance for drug transport and delivery in non-vascular tumor tissue.

Hydrogels of varying complexity are routinely used as scaffolds and 3D structures for in vitro tumor models to increase physiological relevance within pre-clinical cancer research. Relatively simple hydrogels such as agarose are well characterised, meanwhile biomimetic gels containing collagen and fibrin(ogen) have been studied to a much lesser extent. In this study, hydrogels mimicking the biophysical characteristics of liver cancer progression were investigated in terms of their UV-properties and influence on diffusion coefficients of different substances. UV-imaging technology was used to both visualize and quantify the diffusion process in a simple and rapid way. In general, agarose gel diffusion agreed well with predictions using the Stokes-Einstein equation meanwhile the biomimetic gels reduced diffusion coefficients by up to 70%. For doxorubicin, spatio-temporal tissue concentration modelling was used to translate in vitro diffusion to the more clinical context of tumor penetration in a solid liver tumor supplied by arterial blood.