By mixing cells with a certain silk protein, the cells can be distributed more evenly and grow into a tissue imitation, new research at Linnaeus University and KTH Royal Institute of Technology shows. The method can be an interesting alternative for constructing functional tissue, such as skeletal muscles.
All tissues in the body are made up of cells that are integrated into a support of a so-called extracellular matrix (ECM). This matrix is in the form of a three-dimensional microfiber network with specific sites for cell anchorage.
Using genetic engineering, a protein sequence from natural ECM can be functionally fused to so-called recombinant silk proteins. Such a silk protein, FN-silk, which harbours a protein sequence from fibronectin, has the ability to self-assemble into networks of microfibers under body-like conditions.
“We have developed a method where cells and an FN-silk solution are mixed before microfibers are formed. Thus, the cells become uniformly integrated between the microfibers when they are formed, resulting in a 3D network where the cells grow and spread out more efficiently than when encapsulated in a hydrogel”, says Ulrika Johansson, associate professor of biomedical laboratory science at Linnaeus University and one of the main researchers behind the article.
Co-culture of cells
The method enables differentiation of stem cells in 3D as well as facile co-culture of several different cell types. The article also shows that the inclusion of endothelial cells leads to the formation of vessel-like structures throughout the tissue constructs of the silk microfibers.
“This method of forming silk microfibers in the presence of cells is a viable alternative for 3D cell cultures and to construct functional tissue, such as skeletal muscles”, says Ulrika Johansson.
The article is entitled Assembly of functionalized silk together with cells to obtain proliferative 3D cultures integrated into a network of ECM-like microfibers and has been published in Scientific Reports, which is part of Nature.com: www.nature.com/articles/s41598-019-42541-y.