Biological tissues are built when cells anchor to specific sites on a 3-D microfiber network in an extracellular matrix (ECM). Scientists are keen to recreate biological tissues in the lab using bioinspired tissue engineering and genetic engineering, to form functional ECM motifs fused to recombinant silk proteins. Under adequate physiological conditions, bioengineered silk proteins and fibronectin-silk (FN-silk) can self-assemble into microfiber networks that mimic native ECM.
In a recent study, Ulrika Johansson, Mona Widhe and co-workers at the interdisciplinary departments of Biotechnology, Biomaterials Chemistry, and Immunology in Sweden developed a method to include mammalian cells into a silk solution before assembling silk into constructs, to form uniform cell-integrated tissue-like microfibers. The resulting 3-D scaffold constructs showed improved cell proliferation (growth) and homogenous cell spreading compared to cells encapsulated in hydrogel. The results of the study are now published in Scientific Reports.
The scientists confirmed cell attachment on fibronectin-silk constructs (FN-Silk) in the work by observing filamentous actin and by defining focal adhesion points of the attached, elongated cells. They maintained cell viability for 90 days in the cell-FN/silk surfaces and showed scalability of the method to macro-sized 3-D cell cultures. The silk microfiber bundles with encapsulated cells maintained biomechanical strength and extendibility much like human arterial walls.