Scientists have developed a method for transplanting the human brain organoids into the developing brain of rats. The transplanted tissue has been successfully recovered and integrated, while the formed area of the crust resembles the neurons of the human being rather than the animal.
Researchers used methods first used in Pasca's lab to create cortical organoids using induced human pluripotent stem cells, which are adult skin cells that have been reprogrammed to a state like immature stem cells.
This method is usually used to produce organoids. In their study, scientists implanted these organoids into the primary somatic cortex of a rat, a part of the brain involved in the processing of sensations.
The researchers found no abnormality in motor or memory, nor any abnormal brain activity in rats who were transplanted with organoids; the blood vessels from the rat's brain successfully supported the implanted tissue that grew over time.
To understand the extent to which transplanted tissue is integrated into the brain, researchers infected the organoid with a viral indicator that spreads through the brain cells when functional connections are available. The traces of this marker after transplant were found in the veteran core and somatosensory cortex, and also observed new links between the thalamus and the transplanted area.
These connections were activated by electrically stimuli and by the effect on rat mustaches, which indicated that they had received and processed sensory information; in addition, researchers were able to activate human neurons in transplanted organoids to modularize rat behavior associated with the search for a reward.
After seven to eight months of growth, the structure and functions of the transplant were more like neurons from the human brain than human organoids stored in the cellular culture are added by scientists, which means that such transplantation can be used to study in depth the various diseases that cause the disruption of the human CNS.