A Two-Layered Agar Matrix for 3D Cancer Cell Culture in Experimental Radiotherapy

The closer a cancer model simulates the natural tumour environment, the more likely is a new therapeutic approach tested in this environment to succeed in clinical trials. A three-dimensional (3D) cell culture model provides several advantages over a simple, single-layer 2D cell culture: it can more closely simulate the cancer cell interactions occurring in a spontaneous tumour invading a living organism. The 3D cultures may be used to simulate a larger cancer cell load, thereby presenting a higher challenge for destruction by therapeutic intervention. In such a model, the nutritional support in the centre of the 3D structure would decrease with increasing diameter, similar to the situation found in a fast-growing tumour. For the purpose of experimental radiotherapy, we have designed a 3D cancer cell model in a two-layered agar matrix. Although this model does not represent a complex tumour microenvironment, we were able to visualise the three-dimensional growth utilising synchrotron-based microCT imaging of cancer cells loaded with gold nanoparticles (GNP) injected and proliferated in an agar matrix. We have also irradiated 3D cell cultures with microbeams, then embedded, sectioned and stained the agar matrices similarly to organic tissue samples. Thus, we have demonstrated the suitability of our in-vitro model for experimental radiotherapy.