Engineering the tumor environment in vitro using peptide-enriched, hyaluronic acid-based hydrogels

Electrochemotherapy (ECT) is a clinically used and effective treatment in the care of melanoma, and recently it was suggested as a promising tool for the treatment of other deep-seated solid tumors (e.g., liver tumors). In general, ECT efficacy is evaluated in vitro on cell suspensions or in adhesion, and in vivo on animal models. Nevertheless, the first two mentioned approaches completely lack extracellular matrix (ECM) components, leading to unreliable results because they do not reflect the natural tissue architecture. To overcome this issue, several three-dimensional (3D) in vitro models, such as spheroids and hydrogel-based cultures, have been proposed to mimic the complex tumor microenvironment. In this frame, a new synthetic scaffold based on hyaluronic acid (HA) and self-assembling peptides (EAbuK) is proposed as an advantageous alternative. HA-EAbuK scaffolds promote spheroids formation where cells experiment cell-cell interactions, but also improve cell-ECM interactions. Liver cancer (HepG2) cell lines were cultured on HA and HA-EAbuK scaffolds and preliminary bioassays were carried out to assess cell viability and spheroids formation. Then, cells were electroporated at different electric field amplitudes. 3D cultures on HA scaffolds and cells in adhesion (2D cultures), electroporated using culture medium or phosphate-based EP buffer, were taken as controls. Our data showed that HepG2 cells cultured on HA-EAbuK scaffolds were already completely electroporated at 800 V/cm, whereas cells cultured on HA started to be electroporated at 1200 V/cm. In 2D cultures, HEPG2 cells were electroporated at 1000 V/cm and 1200 V/cm in EP buffer and in culture medium, respectively. Collectively, our preliminary results suggest that HepG2 cell cultures on HA-EAbuK hydrogels may represent a promising tool for in vitro evaluation of EP efficiency.