Cancer researchers are increasingly using three-dimensional models of tumors - 3D cell cultures - in diagnostics and so-called theranostics. Researchers writing in the journal Applied Materials Today, suggest that multicellular tumor spheroids (MCTS) are the most accessible and economical models to date.

These are already widely used because they can contain heterogeneous populations of cells of differing metabolic activity, growth and proliferation kinetics, and so simulate a growing tumor. That said, the lack of vascularisation means that the outer surface is exposed to nutrients and can thrive while the inner cells can become necrotic. Despite their limitations, the use of novel nanomaterials is also now playing a role in the field of cancer diagnostics and therapy. A new paper could help promote breakthroughs that could translate into clinical practice sooner rather than later [Mapanao, A.K. et al., Appl Mater Today (2020); DOI: 10.1016/j.apmt.2019.100552]

The team points out that 3D tumor models have been around for many decades going back as far as the early twentieth century. However, it was in 1988, that Robert Sutherland emphasized the potential of tumor spheroids for novel therapeutic approaches. Recent renewed interest and developments are bringing them to the fore once again. This coupled with the rapid development of nanomaterials as anticancer agents or as targeted carriers of chemotherapeutic compounds means that there is a need to look at how these living structures might best be used to test and trial new approaches. Moreover, biological models are very much at the forefront of the search for viable alternatives to laboratory tests involving live animals, where the models can function is physiologically accurate systems.

The team's review of the state of the art shows that we do not yet have a perfect tumor model that reflects all the physiological features of an actual tumor in a living organism nor of the tumor microenvironment (TME). Nevertheless, the advances they discuss are pushing beyond the limitations of the current models and helping researchers develop new ways to build, or grow, such models that are amenable to the testing of nanomaterials.

They point out that 2D cell culture models remain important but add that the recent increased attention on 3D tumor models may well be partly due to the concomitant increased attention in nanomedicine. There is now the potential for 3D models to be created that use primary cell cultures from the patient themselves so opening up the possibility of personalized screenings.

Click here to read the article in the journal.