Human ‘Mini-Brains’ Implanted in Mice React to Light in Scientific First

Think of if lost, deteriorated, or diseased brain parts could be regrown in the laboratory and transplanted for a new lease on life. Scientists at the University of California San Diego have gotten us closer to that fact. Human cortical organoids (or ‘mini-brains’) transplanted into mice were not just linked to the host’s vascular system. They responded to pulses of light in the guinea pig’s eyes in similar methods to the surrounding brain tissue.

Over several months, researchers used an ingenious imaging system to gauge electrical tasks in the organoid that showed an incorporated response to visual stimuli.

It is the first time scientists could confirm functional links in a transplanted human brain organoid in real-time, greatly thanks to enhancements in implants capable of determining subtle neurological signaling on a fine scale.

Explanation of the authors

“We imagine that further along the road, this mix of stem cell as well as neurorecording technologies will be used for modeling illness under physiological conditions at a level of neuronal circuits, examination of candidate treatments on patient-specific hereditary history, and analysis of organoids’ potential to restore specific lost, degenerated, or damaged brain areas upon integration,” the authors write.

The team of neuroscientists and engineers, led by neuro engineer Duygu Kuzum, created their new recording system to gauge brain wave tasks at both a macro and mini level simultaneously.

The setup uses flexible and transparent microelectrodes made from graphene that can be implanted into particular brain parts. This highly-tuned tech accurately presents spikes in the neural task from both the transplanted organoid and bordering brain tissue as they occur.

Less than a month after transplantation, researchers found their human organoids had developed functional synaptic links with the remaining of the mouse visual cortex.

Two months later, the foreign tissue had even further incorporated into the host’s brains.

Stem cells

In 2019, for example, scientists grew pluripotent stem cells into a pea-sized ball of two million arranged nerve cells that penetrated its surroundings for neighborly connections.

Pluripotent stem cells also create the role of human brain organoids. They can distinguish into a wide range of tissues and organs. However, only if they are bathed in the appropriate cocktail of molecules. However, that mixture is exceptionally complex and based upon very particular timing, which scientists are still working out.

In 2021, headings were made when a brain organoid commenced creating simple eye structures, and yet the feasibility of achieving functional ‘sight’ in a lab-grown brain is still a long way off.

On the other hand, implanting human brain tissue expanded from stem cells into a developed visual cortex could be a more realistic goal. Studies have achieved this prior in rats. However, determining whether the foreign graft is actively getting functional input from the remainder of the brain has been more challenging.

Standard metal electrodes do not offer a clear field of view to the brain, so scientists have to remove the electrodes to see the sensory cortex correctly, which can ruin the success of a tissue graft.

Transparent electrodes assist in solving that issue. Utilizing a fluorescent imaging technique under the microscope, researchers at UCSD have shown that light pulses can promote transplanted human organoids within a mouse brain.

“We visualize that, further along, the road, this mix of stem cells, as well as neuro recording technologies, will be used for modeling illness under physiological problems; checking out candidate treatments on patient-specific organoids; as well as examining organoids’ potential to recover specific lost, degenerated or damaged brain areas,” says Kuzum.

Read the original article on Science Alert.

Read more: Spectacular Sights of Earth, Moon Revealed by Danuri Lunar Orbiter.