Scientists publicly announced in the journal Nature on March 16 that they have successfully created a new human stem cell with just a single copy of human genome instead of the typical two. These are the first human cells that are capable of dividing and replicating with only one copy of DNA of a parent.
The findings was made by the scientists from the Hebrew University of Jerusalem, Columbia University Medical Center (CUMC) and The New York Stem Cell Foundation Research Institute (NYSCF). The new stem cells are believed to be able to be transformed into any tissue in the human body.
“This study has given us a new type of human stem cell that will have an important impact on human genetic and medical research,” said Nissim Benvenisty, MD, PhD, Director of the Azrieli Center for Stem Cells and Genetic Research at the Hebre University of Jerusalem and principal Co-author of the study.
“These cells will provide researchers with a novel tool for improving our understanding of human development, and the reasons why we reproduce sexually, instead of from a single parent,” added Benvenisty.
As we have known from schools, most cells in our body contain information in the form of DNA inherited two sets of chromosomes, 46 in total, 23 from the mother and 23 from the father. They are called “diploid”.
Reproductive egg and sperm cells are exception, called “haploid” cells, since they contain one set of 23 chromosomes and cannot normally divide by themselves to generate more eggs or sperm.
This work has existed as a basis for the human inheritance, but the scientists found that it leads to significant limitations for medical research. As there are two copies of each gene, scientists have found a range of challenges to discover defective and edit mutations that may cause disease.
“One of the greatest advantages of using haploid human cells is that it is much easier to edit their genes,” explained Ido Sagi, the PhD student who led the research at the Azrieli Center for Stem Cells and Genetic Research at the Hebrew University of Jerusalem. In diploid cells, detecting the biological effects of a single-copy mutation is difficult, because the other copy is normal and serves as “backup.”
There are many previous attempts to create embryonic stem cells using human egg cells, but they did not work. However, in this latest study, they triggered unfertilized human egg cells into dividing. They then used a fluorescent dye to highlight the DNA and isolated the haploid stem cells containing only 23 chromosomes.
The researchers found that these haploid stem cells were able to differentiate into a range of other cell types, including nerve, heart, and pancreatic cells, while retaining a single set of chromosomes.
The findings will be a powerful help for a lot genetic and medical researches, like cancer research and regenerative medicine, as well as cell-based therapies for diseases including blindness, diabetes and other conditions in the future.