New 'biohybrid' implant will restore function in paralyzed limbs

The researchers combined cell therapy and bioelectronics into a single device, improving functionality and sensitivity.

In this case, they sandwiched a layer of muscle cells that were reprogrammed from stem cells between the electrodes and the living tissue. This led to device integration with the host's body, preventing the formation of scar tissue. For the time time, the cells survived on the electrode for 28 days - the duration of the experiment.

First, the researchers designed a biocompatible flexible electronic device thin enough to be attached to the end of a nerve. According to the release, a layer of stem cells, reprogrammed into muscle cells, was then placed on the electrode. 

It is to be noted that this is the first time such a type of stem cell (induced pluripotent stem cell) was used in a living organism in this way.

"These cells give us an enormous degree of control," said Barone. "We can tell them how to behave and check on them throughout the experiment. By putting cells in between the electronics and the living body, the body doesn’t see the electrodes; it just sees the cells, so scar tissue isn’t generated."

A new approach to neural implants

The Cambridge biohybrid device was implanted into the paralyzed forearm of the rats. Before implantation, these stem cells had already been transformed into muscle cells. They integrated easily with the nerves in the rat's forearm. 

The rats didn't have movement in their forearms, but the device picked up the signals from the brain that controlled movement. The device would help restore function once connected to the rest of the nerve or a prosthetic limb.

The device has several advantages. It is easier to integrate and guarantees long-term stability, but it is also small enough that the implantation would only require keyhole surgery. The device could also be used to control prosthetic limbs.

"This interface could revolutionize the way we interact with technology," said co-first author Amy Rochford from the Department of Engineering. "By combining living human cells with bioelectronic materials, we’ve created a system that can communicate with the brain in a more natural and intuitive way, opening up new possibilities for prosthetics, brain-machine interfaces, and even enhancing cognitive abilities."

The team is working on optimizing the devices and has filed a patent application for the technology.

The results are reported in the journal Science Advances.

Study Abstract:

The development of neural interfaces with superior biocompatibility and improved tissue integration is vital for treating and restoring neurological functions in the nervous system. A critical factor is to increase the resolution for mapping neuronal inputs onto implants. For this purpose, we have developed a new category of neural interface comprising induced pluripotent stem cell (iPSC)–derived myocytes as biological targets for peripheral nerve inputs that are grafted onto a flexible electrode arrays. We show long-term survival and functional integration of a biohybrid device carrying human iPSC-derived cells with the forearm nerve bundle of freely moving rats, following 4 weeks of implantation. By improving the tissue-electronics interface with an intermediate cell layer, we have demonstrated enhanced resolution and electrical recording in vivo as a first step toward restorative therapies using regenerative bioelectronics.