The activity of proteins is generally studied by adding them as soluble protein in the cell culture medium, the cells being themselves grown on glass or plastic surfaces. However, the rigidity of these surfaces affects the cell response. In a their Biomaterials research paper, researchers at IRIG [Collaboration] have successfully tested a patented process for studying the biological activity of proteins delivered to cells via soft and stiff biomimetic films.

These self-assembled films, which are less than two micrometers thick, are composed of biopolymers present in the extracellular matrix of our body. The films of controlled rigidity are deposited using an automated process at the bottom of multi-well cell culture microplates. The researchers used this process to study the biological activity of four proteins of the bone morphogenetic proteins (BMP) family, involved in bone and muscle formation. They discovered the specificity of some BMPs in cell adhesion and cell spreading. These properties could not be observed on a rigid support. Many cell and developmental biology experiments aimed at studying the role of BMPs in physiological and pathological conditions may be revisited by delivering BMPs via the biomimetic films of controlled stiffness. Thus, the stiffness control appears to be a major parameter in the study of the biological activity of BMPs. More broadly, this works opens innovative perspectives to study the activity of other proteins or therapeutic molecules.



Example of multi-well plates with flexible films on the bottom.
© Paul Machillot.