Today’s #RealSci_Nano thread is all about my favourite topic and the tagline for this week – how to use sound to “make cells dance.”

This is a video of cells patterned by an ultrasound wave...read on to hear more about how we can use this for #tissue #engineering!

What is going on here? Well, what we have here is a "standing wave" which means that we have made sound waves but they are not travelling. This creates static regions of pressure - some higher than usual, some lower than usual, and some unchanged.

This is a slightly unusual situation for cells to find themselves in!

Cells in areas of high and low pressure will feel an "acoustic radiation force" which pushes them into areas of unchanged pressure. This is what we see in the video - the cells accumulate in the "nodal plane."

What is great about this is that you don't need to modify/label the cells or the culture media in any way! This works because the cells have a different density and compressibility to the surrounding liquid.

There are things that can mess with this - gravity, viscosity, cells sticking to things and an effect called acoustic streaming. A lot of what I do is trying to figure out how to get around these problems!

...but when you get the conditions right, you can start to pattern cells in gels. This is an image of cells all lined up in a collagen hydrogel.

This is exciting because this means we can start making a patterned tissue!

We first used this to make muscle - because muscle is naturally made of parallel bundles of long cells. Using our sound waves, we were able to make something similar!

If you are interested in this, see our Advanced Materials ( @AdvSciNews) paper here:

https://doi.org/10.1002/adma.201802649

The possibilities for this are endless! I worked with @sonic_bruce and his team to make these patterning devices - they are easy to use and compatible with normal cell culture. By tuning the ultrasound properties we can make all sorts of different cell patterns!

I'm now working with my brilliant student @katya_pch to use these devices to make different patterned tissues and create smart cell culture systems!

Others have also worked with acoustic cell patterning - my favourite is this work by Peer Fischer's group published in Advanced Materials ( @advscinews):

https://doi.org/10.1002/adma.201904181

Here they cleverly used acoustic holograms to make completely customized cell patterns!

If you are interested in using sound, magnets or light to build complex tissues then you can read more about it here in this @TrendsinBiotech review:

https://doi.org/10.1016/j.tibtech.2019.07.005