External forces are an important factor in tissue formation, development, and maintenance. We have developed a method to stretch soft hydrogels, such as fibrin and collagen gels, from their circumference, using an elastic silicone strip.
Advantages of this method include the ability to strain extremely soft hydrogels in 3D while executing in situ live microscopy, and the freedom to manipulate the geometry and size of the sample.
By considering the design of various geometries, we use our method to program strain gradients along different chosen axes, providing a framework for engineering tissues with complex gradient structure, such that occur in interfacial tissues such as tendon-bone or cartilage-bone.
Relevant papers:
Mechanical communication between cells
The unique nonlinear mechanics of the fibrous extracellular matrix (ECM) facilitates propagation of forces, supporting a mechanism of long-range cell-cell mechanical communication that would be impossible for linear elastic substrates. When seeded in fibrous gels, pairs of cells or cell aggregates can induce bands of deformed gel extending between them, indicating their mechanical coupling. We use computational finite element simulations and biological experiments to reveal how mechanical forces, exerted by contractile cells, are transmitted in fibrous nonlinear environments, and how these forces can reach out neighboring cells and regulate their biological activity.
Related papers:
Force transmission in anisotropic fibrous environments
The mechanical and structural properties of fibrous materials dynamically evolve and develop as they are strained. Together with Dr. Raya Sorkin (Chemistry, TAU), we use laser tweezers to study how forces propagate in fibrous gels that are put under tension and become elastically anisotropic. This line of research provides insight into the mechanisms how mechanical cues are transmitted between biological cells, and provide inspiration for the design of new biomaterials.
Forces exerted by growing roots
Plant roots are considered one of the most efficient soil explorers. As opposed to the penetration strategy of other organisms, that is based on pushing through soil, roots penetrate by growing, adding new cells at the tip and elongating over a well-defined growth zone. In collaboration with Dr. Yasmin Meroz (Plant Sciences, TAU), we study the forces applied by plant roots in agar gel by traction force microscopy, and use finite element modeling to reveal the advantages of the growth mechanism.
Scaffold based on coral-derived collagen fibers
In collaboration with Prof. Rami Haj-Ali (TAU, Mechanical Engineering), we extract centimeter-long collagen fibers from Sarcophyton soft corals, and wrap them around frames to create aligned fiber arrays. We study their biocompatibility and ability to support formation of various oriented tissues, such as skeletal muscle tissue.
Related papers:
Seaweed cellulose scaffolds from green macroalgae
In collaboration with Prof. Alexander Golberg (Porter environment, TAU), we apply decellularization-recellularization approach of Marine macroalgae species Ulva sp. and Cladophora sp. to produce cellulose scaffolds for in-vitro mammalian cell growth. We test their biocompatibility and ability to support tissue engineering.
Related papers:
Nurit Bar-Shai, Orna Sharabani-Yosef, Meiron Zollmann, Ayelet Lesman, Alexander Golberg. Seaweed cellulose scaffolds derived from green macroalgae for tissue engineering. Scientific Reports. 2021 Jun 4;11(1):11843. doi: 10.1038/s41598-021-90903-2. PMID: 34088909.