Stem cell stories that caught our eye: growing better bone, synthetic diaphragms, nerves that make music

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Image of the hydrogel containing mesenchymal stem cells.

Image of the hydrogel containing mesenchymal stem cells. Credit Harvard SEAS/Wyss Institute

A better way to grow bone.  The term hydrogel gets tossed around a lot in tissue engineering discussions. The porous, generally pliable materials used to hold stem cells in place when creating new tissue are far from uniform. They have highly variable properties. Making a version that mimics the natural environment where bone grows allowed a Harvard team to grow better quality bone and more of it than prior methods.

It turns out stem cells prefer to turn into bone when grown in an environment that readily relaxes in response to stress.  Think of Silly Putty instead of hard rubber.  When the Harvard team grew stem cells on a fast relaxing hydrogel, they saw an increased number of stem cells turn into bone and those cells continued to create more bone for weeks.

“This work both provides new insight into the biology of regeneration, and is allowing us to design materials that actively promote tissue regeneration,” said David Mooney, who led the team.

In a press release from the university picked up by Science Newsline, the researchers speculated that the findings should both enable better bone repair grafts, but also generate more research into how mechanical properties influence cell behavior.

Replacement diaphragms.  Paolo Macchiarini, the Italian scientist based at Sweden’s Karolinska Institute who created much news and a bit of controversy with surgeries to give patients lab-made windpipes, burst back into the news this week. This time with replacement diaphragms, that muscle in the abdomen critical for breathing. The tireless muscle is much more complex than the static windpipe, or trachea, and Macchiarini readily noted that his current work in rats is not nearly ready for patients.

When it is, it could be a life changer and maybe life saver for the one in 2,500 babies born with defects in their diaphragm. Using a technique similar to his work with the trachea, his team took stem cells from bone marrow and grew them on an artificial polymer scaffold.  When they transplanted sections of the synthetic diaphragm into a damaged diaphragm in the animals the sections of muscle beat in synchrony with the rest of the rat’s existing diaphragm. But Macchiarini notes they have no idea why this happened and until they do, the procedure will not be ready for the clinic.

“If you ask me why it happens, to be very honest I don’t know,” he told Alice Park writing for Time. “I can just say that we saw many proteins, extracellular matrix components that belong to the nervous system. So probably via this, the muscle was able to contract again.”

The team wants to refine the process by determining which of the stem cells are destined to become muscle.  The university put a bit more detail in a press release.

Video on synthetic windpipe.  Since Macchiarini’s early reports of giving patients new windpipes, or tracheas, several teams around the world have tried to refine the procedure. The East Coast TV station WFMZ did an easy-to-understand segment on one team’s efforts at Mount Sinai in New York City. So far, their work remains confined to lab animals, but hey hope to treat patients within 18 months.


Lab grown trachea. Credit University College London.

Neural music synthesizer.  On first read, this one sounds a little far fetched. The headline says “world’s first neural synthesizer.” And even crazier, the artist did it with iPSC-type stem cells reprogrammed from his own skin.

The web magazine Fact ran a short piece in its music section. This is how the writer there described the synthesizer:

“Music is fed into the neurons as electrical stimulations and the neurons respond by controlling the synthesizer, creating an improvised post-human sound piece.”

Image from Guy Ben-Ary website.

Image from Guy Ben-Ary website.

It provides a bit more description and notes that the project by artist Guy Ben-Ary is supported by a creative Australia Fellowship award to develop a biologic self-portrait. The article does provide a link to Ben-Ary’s web site, which goes into great detail on every aspect of the project called “cellF.” He describes everything from the procedure for making the stem cells in Barcelona to how they are grown into nerve cells in special plates that can both send and receive signals to respond to the natural electro physiology of nerves.  He explains the special lab plates in this way:

“The dishes that host my ‘external brain’ (neural networks) consist of a grid of electrodes that can record the electric signals that the neurons produce and at the same time send stimulation to the neurons – essentially a read-and-write interface.”

The first concert using the synthesizer occurred October 4. A guest musician, a drummer from Tokyo, provided the sound that was converted to electrical stimulus for the nerves. The nerves responded by controlling the music synthesizer. The video documenting the performance is due to be posted later this month.

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