Human induced pluripotent stem cells reprogrammed into germ-cell precursors

Los Angeles, United States, January 28: People battling infertility may find a reason to rejoice as researchers have reprogrammed human induced pluripotent stem (iPS) cells to ultimately become eggs and sperms.

Researchers from University of California, Los Angeles, in the two-and-a-half year long study period have successfully converted the iPS cells to form germ-line precursors, which have genetic characteristics, quite similar to eggs and sperms.

The unique kind of study, led by senior study author Amander Clark, was published online on Jan. 26 in the journal 'Stem Cells'. Clark is a scientist at Broad Stem Cell Research Center, UCLA and an assistant professor of molecular, cell and developmental biology.

"This finding could be important for people who are rendered infertile through disease or injury. We may, one day, be able to replace the germ cells that are lost. And these germ cells would be specific and genetically related to that patient," said Clark.

She, however, remarked that still substantial research and time is required before the cells could be employed to treat infertility. The process of generating high-quality germ cells in the laboratory may take several researches over the years.

Research team explained that cells, as skin cells, from an infertile person could be extracted and reprogrammed to become iPS cells. These iPS cells, in turn can be converted to any cell-type in the body, just like embryonic cells. This specific quality can enable the cells to turn into sperms and eggs after their transformation into germ-line precursors.

But interestingly, Clark and her team found that germ-line cells sourced from human embryonic stem cells were different from germ-line cells from human iPS cells. According to the researchers, in the set of human iPS-derived germ cells some essential regulatory procedures were not executed properly.

Clark urged that continuous studies are required in the field of human embryonic stem cells, which are deemed controversial, but researchers tend to use remnant stuff from IVF procedures, which would otherwise be destroyed.

According to Clark, "Further research is needed to determine if germ-line cells derived from iPS cells, particularly those which have not been created by retroviral integration, have the ability to correctly regulate themselves like the cells derived from human embryonic stem cells do."

"When we looked at the germ cells derived from embryonic stem cells, we found that they regulated as expected, whereas those from the iPS cells were not regulated in the same way. We need to do much more work on this to find out why," she added.

In the germ-cell formation procedure, it is crucial for the cells to go through some explicit biological procedures including regulation of imprinted genesdefine, which helps these cells to function properly. Resulting eggs and sperms may not behave as desired, and any discrepancy in the procedure may further destroy the fertilization.

Clark and her team plan to examine more iPS cell lines and evaluate the resulting germ cells derived from them to determine if the incorrect regulation remains a problem.

Clark maintained that the procedure of deriving germ-cells from embryonic stem cells is tough and low-yielding and creating germ cells from iPS cells is also equally difficult. However, giving those cells flourishing environs amidst fetal gonadal cells proved favorable.

While recent infertility treatments include surrogacy, donor eggs and sperms and IVF procedures, eggs and sperms reprogrammed from the patients’ own set of cells could add a significant alternative to the already available choices. Clark believes that problems like low sperm count can be easily dealt with this approach.