MATSUYAMA, Ehime - A research group has succeeded in directly reprogramming somatic cells from melon-headed whales into neurons for the first time - a development that is likely to contribute to research on neurotoxicity in marine mammals and show how pollutants affect them.
The findings of the research group led by Mari Ochiai, assistant professor of environmental toxicology at Ehime University Center for Marine Environmental Studies, were published in the American academic journal Environmental Science Technology.
According to the publication, the research group cultivated fibroblasts or individual tissue cells, via the connective tissue of melon-headed whales, after around 160 of them were stranded on the coastline of the Ibaraki prefecture city of Hokota in 2015.
After several weeks of treating the cells with a solution mixed with low molecular weight compounds, the group obtained cells with morphology similar to that of neurons. Methods including gene expression analysis revealed that they were artificially induced neuronal cells.
Direct reprogramming, or the conversion of somatic cells into other forms without the need to transition through induced pluripotent stem cells, is attracting attention in fields including fundamental research and regenerative medicine. The group's research marked the first time for whale cell to be reprogrammed directly.
The group then exposed these reprogrammed cells to substances called polychlorinated polyphenyls OH-PCBs that are metabolized from polychlorinated biphenyls PCBs a common type of environmental pollution. After 24 hours, over 80% of reprogrammed neurons self-destructed in a process called apoptosis. OH-PCB's may have disrupted cells if exposed to them.
Apoptosis is a mechanism that destroys cells that are either severely damaged or detrimental to the body's own existence. It plays a role not only in the formation of fetal limbs, and the disappearance of genetic cancerous cells, but also in the removal of cells infected with a virus or having human abnormalities such as being webbed cells.
Persistent organic pollutants which have been released into the environment have spread throughout the world and a survey by Ehime University in the 1990 s found 265 types of organic pollutants in marine mammals. The research group also detected PCBs in the brains of melon-headed whales were stranded in Ibaraki, including the one they studied.
After studying marine biology at Ehime University after graduating with distinction from the University of California, Santa Cruz, Ochiai has continued to see contaminants remaining in orca and dolphins in 2009.
Ochiai said that Pollutants can cause issues other than apoptosis. We would like to explore complex contamination caused by different substances and apply this toxicity evaluation technology to other marine mammals.