Biological Physics for Everyone
Our lab overview -- 2020
We present our research generated media for general audience. Please feel free to comment or send to us email inquiries.
This video explains a trick of cancer cells -- to be able to switch between different programs of migration -- that makes them very difficult to target.
This video shows fibroblast cells responding to ATP. When exposed to ATP, these cells increase there intracellular calcium concentration, which can be monitored using chemicals that produce fluorescent light when binding to calcium ions. So when you see a cell becomes bright, it means calcium concentration is rising inside the cell cytoplasm. Interestingly, we found the cell are communicating to each other about how much ATP they perceived, and as a whole, they can detect ATP better than individuals. Note that ATP is not only the 'energy currency' of cells as you have learned since high school, it is also one of the most important molecule cells use to 'signal' to others.
This Image shows the microscopic structure of a collagen gel, the white bar corresponding to 0.1 mm in length. Collagen is a major component of mammalian tissue, and research labs from all over the world use collagen gel to mimic physiological conditions. Although it usually comes as a soft, but solid gel, 99% of the mass is actually water. As you can see, there are lots of empty space between those collagen fibers, which is made of polymerized collagen proteins.
This video was made by one of our undergraduate researchers to introduce the chemotaxis of cancer cell -- a process where cancer cells seek nutrients and other types of favorable chemicals.
This video shows breast cancer cells MDA-MB-231 migrating in a 3D collagen gel. These cells were originated from a cancer patient in 1973 and have been dividing ever since. (cancer cells are immortal !) This experiment provides a simplified version of how cancer cells invade in human body: they can move as a group, loosely connected but object oriented and occasionally get distracted. Just think about having a group of three-year-old kids in a 100-meter marathon.
Every cell looks different, and their shapes are always changing. Like us, the shape of a cell is supported by its skeleton -- cytoskeleton. Actin is a major component of cytoskeleton as shown in green color in the above. Actin forms long, think fibers just as collagen does. Aside from the cytoskeleton, cell can also adhere to its surrounding objects (so called substrates, or extracellular matrix) and they can pull on those adhesion sites. These adhesion sites are called focal adhesions, and they are labeled in red in the above.
Cells can produce forces ( and of course, that is the basis of how we generate forces). Although that is quite small, we can use the trick called traction force microscopy to measure it. We put the cells on a very soft surface, and use the fluorescent beads embedded there (mid panel) to measure the deformation caused by the cells while they are moving, dividing or colliding (left panel). Using a more fancy form of Hook's Law, we can even calculate how much force they produce ( right panel).
A movie of breast cancer cell migration can already tells you how un-regulated they are. As you can see in the video, their shapes are very irregular, vary greatly from one to another. They quickly make membrane protrusions and pull back without actually migrating... On a population level, these irregularities help them to invade into other part of body -- metastasis.