Waves that break on the shore, shaping sand in fantastic structures; wind that not only changes the landscape, but also breathes life into grasses, leaves and water; and raindrops that cause expanding circles when they hit water: Such natural phenomena served as inspiration for Tiziano Serra, Focus Area Leader at the AO Research Institute in Davos and co-founder of MimiX Biotherapeutics. Prompted by curiosity, this materials scientist and passionate amateur musician found out what happens when sound waves hit cells.
In November 2016, Tiziano Serra placed cells in a Petri dish on a loudspeaker. The result exceeded his expectations. “Within seconds,” he explains, “the cells grouped together in geometric patterns.” In further experiments, he found that the type of pattern depended on the wavelength: The cells exposed to sound formed concentric circles or structures resembling a four-armed fidget spinner (a kind of hand-held spinning top). Tissue organisation via sound – this idea, supported by the AO Foundation in Davos and a Swiss National Science Foundation grant, led to the founding of MimiX Biotherapeutics in 2019, a company set up to apply the technology in the clinical setting.
Although the cells are now no longer bombarded with sound waves from loudspeakers, the principle remains the same: Within a hydrogel, a network swollen with water, they are exposed to sound for a few seconds and fixed in place as soon as the desired geometry has formed. The resulting implant is a three-dimensional piece of artificially produced tissue, which should pose few problems when it comes to scaling up. Preclinical studies on mice show that the implants serve as germ cells for physiological structures: They organise diseased or defective tissue in the immediate vicinity and form vessel-like structures that are essential for healing. In addition, the body tolerates the implants very well because they are made from its own cells. They are thus predestined for applications in reconstructive medicine and could become a game-changer in bone or skin regeneration, as well as in the development of artificial mini-organs.
In order to embed different cell types and increase the implants’ complexity, several of them can be stacked. This does not equate to 3D printing in the conventional sense, but leads to a targeted spatial arrangement of cells. The procedure is fast and well tolerated by the cells, it generates quasi-physiological structures and is technically simple. So simple that the aim is to use it directly in hospitals’ operating theatres – bedside production, so to speak. The possible applications are not limited to medicine though. Tiziano Serra sees potential for this technology in the production of laboratory-grown meat, where currently, animal muscle cells grow in a container and form a larger mass thanks to a carrier scaffold. However, the typically fibrous structure of steak cannot be produced in this way. To do that, the muscle cells must be able to ravel out in all directions. And that is precisely the strength of sound-induced tissue organisation.
Tiziano Serra has no shortage of visions for the future: “I dream of combining the patented implants with artificial intelligence and conventional 3D printing,” he says in his Davos laboratory, “making the most of each of these three technologies.” Imitating nature to orchestrate life.
Umfassende und weiterführende Informationen zum Thema finden sich im Beitrag «3D bioprinting».