For many years scientists have tried to investigate the true nature of schizophrenia and its causes, now it seems that scientists may have found a significant clue, and it lies in the cells.
A recent study, condemned by some as ‘unethical’, for its use of ‘chimeras’ (animals created by transplanting cells from one species to another), has shown that mice injected with cells from schizophrenic patients displayed all the same signs of schizophrenia.
The study which took place at the university of Rochester Medical Center injected human cells into newborn mice. Lab mice that were injected with the cells of patients suffering from schizophrenia displayed symptoms such as being afraid of strangers, anxiety and memory loss. They used the skin cells from three people with schizophrenia, and three people without the condition. The skin cells were then transformed into stem cells and then glia-making cells which were injected into the brains of newborn mice.
The mice brains injected with the cells from the schizophrenic patients didn’t produce the same amount of myelin as a healthy brain. Myelin is a fatty molecule which allows neurons to carry electrical signals which constitute our thoughts and feelings. They also had trouble turning into astrocytes which help neurons connect and set synapse ‘firing’ rhythms. When the rhythm is uncoordinated it can lead to problems in a developing brain.
Investigating the causes even further still, scientists analysed the genes of the glia in people with schizophrenia, and found that there were 118 genes that were off when they should have been on compared to glia in healthy people. This abnormal gene expression causes ‘structural havoc’ in the brain’s wiring.
Schizophrenia is a mental disorder that affects an estimated 1% of the population. Previous research into the condition has identified a problem with the brain’s neurons as one of the primary causes of the condition, specifically the brain’s support cells ‘glia’.
Symptoms of schizophrenia include behavioural and speech problems, delusions, hallucinations, depression and sleep disruption.
Mice who had human schizophrenia cells displayed symptoms such as being afraid to explore their maze, becoming more anxious, less social, less able to feel pleasure and losing sleep.
Implications for the future
There is still some uncertainty to whether the symptoms displayed by the mice exactly replicate those seen in patients suffering with schizophrenia, but in addition to shedding light on how abnormal glia can cause schizophrenia, the study underlined how readily mouse brains accept human cells.
However, the creation of a chimera with human cells in its brain raises ethical concerns, as the result would be the creation of a brain closer to that of a human than a mouse.
Under a 2015 moratorium, the National Institutes of Health does not fund research that transplants human stem cells into early embryos of other animals.