Periodic Reporting for period 2 - VISCOMATRIX (Dynamic regulation of tissue response by matrix viscoelasticity)
Período documentado: 2022-12-01 hasta 2024-05-31
VISCOMATRIX is focused on a highly relevant system which is the mammary gland and related mammary tumours. This choice is based on: (i) First, breast tumour impacts approximately 1 in 8 women. ii) Second, breast mammary gland is a viscoelastic tissue. (iii) Third, even if the role of viscoelasticity is unknown, it is well known that mammary gland and tumour development is associated with strong changes in mechanical properties. Our preliminary results show that viscoelasticity significantly affects tissue function. Therefore, as all tissues are viscoelastic, the biomedical impact of the importance of viscoelasticity is expected to be dramatic and impact fields ranging from regenerative medicine to cancer, and fibrosis. In the bioengineering filed, we believe that our findings will affect biomaterial development as well as the development of new imaging techniques to determine the viscoelastic properties of tissues. As to cancer, clinical trials targeting matrix metalloproteinases or integrins have been so far disappointing. The inclusion of viscoelasticity in the equation may provide crucial information to progress disease treatment and develop drugs.
During these first years, we were focused on the development of the hydrogels that we have are currently using and will be used throughout the project. Apart from hydrogels, we have been developing the methodology to be able to perform all the aims of the project. We have invested a significant amount of time to the development of a methodology that spans from single cell measurements to in vivo characterization. This methodology will provide broad applicability and a very powerful set of tools for many different applications. We have done most of the second objective and a significant amount of the first objective. As to the main results achieved so far:
Alginate hydrogels: We have been able to obtain alginate that we have irradiated to generate alginate hydrogels with different molecular weights. Different molecular weights allow us to develop alginate hydrogels with different viscoelasticities and stiffness. We have then mechanically characterized these hydrogels using two main techniques: rheology and Atomic Force Microscopy. With these hydrogels we have been able to start the experiments with epithelial cells as described in VISCOMATRIX. Additionally, we are developing materials with some small regions with different properties as described in 3.2 in VISCOMATRIX.
Role of viscoelasticity in breast cells: As hypothesised in VISCOMATRIX, we have observed that MCF10A cells encapsulated in viscoelastic hydrogels are able to undergo EMT and invade the matrix. However, when these cells are seeded in a more elastic matrix spherical symmetry is maintained and cells are unable to invade. Additionally, cell proliferation is enhanced in viscoelastic matrices. Interestingly, stiffness enhances the influence of viscoelasticity. Even though cells are unable to invade in stiff elastic ECMs, cells invade significantly more in stiff viscoelastic ECMs compared to soft viscoelastic ECMs. In accordance with these results, we have done a RNAseq experiment that shows that most cancer pathways are activated in stiff viscoelastic ECMs. This process seems to be regulated by FAK, Arp2/3 complex and Rac1. Taking into account our bulk sequencing results, we are going to perform single cell sequencing experiments in 2024. Furthermore, we have developed a method to quantitatively measure tissue dynamics and force transmission in live experiments. We observe that spheroids migrate significantly faster in viscoelastic hydrogels and exert larger stress transmission.
We have also been able to set up the AFM and microscope to measure both the ECM composition and the mechanical properties of the tissue.