Map of liver reveals new stem cells
Scientists have drawn up the most detailed map of the liver so far. The process has revealed previously unknown stem cells and genes responsible for the development of liver cancer.
STEM CELLS CAN SAVE SICK TISSUE
Scientists have revealed an unknown cell type in the bile ducts of the liver. It functions as a stem cell and can develop into different types of liver cells. The cell might be used to treat sick tissue.
SCIENTISTS DIVIDE CELL TYPE IN THREE
Just about all known liver cell types can now be divided into subgroups. Hepatocytes exist in three versions, of which one is good at removing ammonia, and another at breaking down substances by means of oxygen.
THE LIVER REVEALS NEW IMMUNE CELLS
The mapping out of the liver has revealed three new subgroups of Kupffer immune cells. They differ from each other by curbing or improving the immune system’s reactions in the liver.
GENES REVEAL CANCER ORIGIN
Comparison of healthy and cancerous livers has identified the genes that trigger cancer development. Scientists observed increased activity of genes that are normally expressed by liver stem cells.
immune cells differed from corresponding immune cells in the blood, and one of the new cell types seems to have a particularly close relationship with the embryo. It produces proteins that recognise the embryo’s cells, while it also releases substances that calm other immune cells. All in all, the decidua map revealed an environment optimised to curb the immune system’s reactions to the embryonic cell invasion. This new insight might help discover ways to treat women who find it hard to get pregnant because their immune cells tend to reject the embryo.
Project reveals cancer genes
Scientists are also busy exploring the liver, one of the body’s most important organs, disarming toxins, purifying the blood and adjusting the metabolism. The liver is also the only organ that can regenerate – even after having been reduced by 75%. Although the liver has been thoroughly explored for more than 100 years, some of its cells have remained hidden from scientists – until the scientists from the Human Cell Atlas project recently mapped out the cells of the liver tissue of nine donors.
The scientists analysed 10,000+ cells. They primarily found familiar cell types, but they also revealed subgroups of liver cells that scientists had never before come across. They discovered a new type of cell in the liver’s bile ducts – a network of passages that direct bile from the liver to the gall bladder. The cell functions like a stem cell and can develop into ordinary liver cells and bile duct cells.
Apart from healthy livers, the project’s scientists also explored cancerous livers – and by comparing the two, they managed to identify a number of genes involved in the conversion of healthy liver cells into cancer cells. This should make it possible to develop extremely targeted treatments that can curb the early stages of liver cancer.
Atlas guides new treatments
Most diseases can be traced back to undesirable changes at the cellular level. A complete atlas of all cells in the body will provide scientists with the optimum information to make accurate diagnoses and develop new treatments.
The scientists from the Human Cell Atlas project are already on the track of more efficient treatments for cystic fibrosis, inflammatory diseases, and cancer.
Armed with their new knowledge about the ionocytes of the lungs and their role in cystic fibrosis, scientists can now work on the development of gene therapies that are specifically aimed at the ionocytes and at correcting their mutated CFTR gene.
Unlike cystic fibrosis, inflammatory diseases can involve hundreds of genes, all contributing to the disease, with many of these genes and their effects still unknown to scientists, even the cells in which they are most active. The Atlas is now changing that. In one example, scientists have compared the maps of cells in the gut tissue of healthy people with those from people with inflammatory gut diseases. They discovered a handful of cells in the sick tissue that did not exist in the healthy tissue, and could also see how more familiar cells changed their activity in the sick tissue. The scientists now have the tools to develop treatments that would remove the sick cells or correct their gene activity.
New knowledge about cancer cells’ gene activity has provided scientists with another new approach. Immune therapy, which helps the immune system combat cancer, has proved promising but is not equally efficient in all patients – and in many cases, is efficient only for a limited time before the cancer cells become resistant. A mapping out of cancerous tissue has shown that cancer cells which develop resistance against immune therapy activate a specific genetic program that protects them against the therapy. Scientists have now discovered a way to deceive the cancer by combining immune therapy with a drug which deactivates this protection program.