Conventional breast cancer treatments such as chemotherapy, are known for triggering side effects and, in some types of cancer, for displaying a limited therapeutic outcome. Therefore, it is pivotal the development of new therapeutic approaches. Two-dimensional (2D) cell culture was, up to recent years, the prime methodology used for anticancer therapeutics screening. However, 2D cellular models are unable to fully reproduce the architecture of solid tumors found in vivo, leading in some cases to an unsuccessful prediction of how cancer cells respond to new drugs. On the other hand, there is a tremendous pressure from institutions governing animal experimentation and animal welfare leagues to reduce the number of animals used in experimentation.
To overcome these limitations associated with the 2D cell culture models as well as to reduce the number of animals used in in vivo assays, researchers started to grow cells in three-dimensions (3D) in order to mimic the features of solid tumors found in vivo. One of the most applied technique to produce these 3D cellular aggregates, also known as spheroids, is Liquid Overlay Technique (LOT). In this technique, cells are forced to form cellular aggregates due to their limited adhesion to certain biomaterials, usually agarose or agar (1).
However, these biopolymers cannot interact with cancer cells, neither establish interactions similar to those occurring between cells and extracellular matrix (ECM) in solid tumors (such interactions are responsible for the activation of cellular signaling pathways that regulate cancer cells behavior). In order to mimic not only the 3D structure but also the cell-ECM interactions that occur in tumors, researchers are currently using ECM components, like hyaluronic acid (HA).
This polymer is one of the main constituents of tumor ECM, it has an essential role in cancer progression and it avoids cell adhesion in vitro. In a recent work from my research group, it was optimized, for the first time, the coating of surfaces with HA that was used for the production of reproducible heterotypic breast cancer spheroids (2). The obtained results revealed that the HA-coated surfaces allowed the production of spheroids that reproduce the 3D structure and the cellular heterogeneity presented by breast solid tumors.
Furthermore, it was possible to control the size, shape, and number of spheroids produced by changing the HA concentration and the number of cells initially seeded. Overall, these breast cancer spheroids assembled on HA-coated surfaces represent a huge improvement for the future development of anticancer therapies.
- Costa, E.C., Gaspar, V.M., Coutinho, P., Correia, I.J. (2014) “Optimization of Liquid Overlay Technique to Formulate Heterogenic 3D Co-Cultures models”, Biotechnology and Bioengineering, 111(8):1672-85. DOI: 10.1002/bit.25210.
- Carvalho M.P., Costa E.C., Correia, I.J. (2017) “Assembly of breast cancer heterotypic spheroids on Hyaluronic Acid coated surfaces”, Biotechnology Progress, in press, DOI:10.1002/btpr.2497.
The study, Assembly of breast cancer heterotypic spheroids on hyaluronic acid coated surfaces was recently published by Ilídio Correia in the journal Biotechnology Progress.