This is the 1/4 videos from the 2nd edition of our Virtual Symposium, featuring the last publications and results from our users in cell biology and mechanobiology.
Part I: Hydrogel patterning techniques for applications in traction force microscopy
Traction force microscopy (TFM) is the main method used in mechanobiology to measure cell forces. We present a protocol to rapidly and efficiently fabricate micropatterned polyacrylamide hydrogels for TFM studies. The micropatterns are first created by maskless photolithography using near-UV light, where extracellular matrix proteins bind only to the micropatterned regions, while the rest of the surface remains non-adhesive for cells. The micropatterning of extracellular matrix proteins is realized by controlled activation of aldehyde groups, resulting in adhesive regions of desired shapes to accommodate either single cells or groups of cells. For TFM measurements, we use dual-layered polyacrylamide hydrogels of different elasticity, and we describe the use of a controlled dose of patterned light to release cell tractions in defined regions for single cells or groups of cells.
Presented by: Ada Cavalcanti, a group leader at the Max Planck Institute for Medical Research in Heidelberg and Member of the Faculty of Biosciences at the Heidelberg University. Her research is centered on the mechanobiology of receptor-mediated cell adhesion. She completed her Master studies at the University of Pennsylvania, USA and then obtained a PhD in Biosciences in 2005 at Heidelberg University, Germany. She spent her postdoctoral years at the Max Planck Institute for Intelligent Systems until she started her group in 2011. She has been awarded in 2008 with the prize “for women in science” from UNESCO-L’Orèal.
Part II: 1D micro-nanopatterned integrin ligand surfaces as tool to modulate cell front and back coordination for directed migration
Cell-extracellular matrix (ECM) adhesion modulated by integrin receptors is a highly regulated process involved in many vital cellular functions such as motility, proliferation and survival. However, the influence of lateral integrin clustering in modulating the cell front and back dynamics during cell migration remains unresolved. Therefore, we developed a 1D micro-nanopatterned migration protocol based on the block-copolymer micelle nanolithography (BCMNL) technique with biofunctionalized gold nanoparticles with the integrin-specific RGD (arginine-glycine-aspartate) motif. Defined 10 mm-wide micropatterned stripes were fabricated consisting of a quasi-perfect hexagonal arrangement of gold nanodots with a mean diameter of 8 nm that serve as an anchoring site for a single integrin heterodimer. The gold nanoparticles were placed with a lateral spacing of 50, 80 and 100 nm to regulate integrin clustering and focal adhesion dynamics. By employing time-lapse microscopy and immunostaining, we propose that the speed, coordination of front-back dynamics and migratory behavior of fibroblasts change according to the nanoscale spacing of adhesion sites.
Presented by: Victoria Levario Diaz, a postdoctoral researcher in the Cavalcanti-Adam group at the Max Planck Institute for Medical Research in Heidelberg. She completed her Master studies and obtained her PhD in Nanoscience in 2021 from the University of Bristol, UK. She joined the Cavalcanti-Adam group in the fall of 2020 to develop protocols combining nanoscience and micropatterning to direct and analyze cell migration.