Genetics

When scientists talk about laboratory stem cells being totipotent or pluripotent, they mean that the cells have the potential, like an embryo, to develop into any type of tissue in the body. What totipotent stem cells can do that pluripotent ones can’t do, however, is develop into tissues that support the embryo, like the placenta. Salk Professor Juan Carlos Izpisua Belmonte, along with first author Jun Wu and researchers from China’s Peking University, discovered a chemical cocktail that enables cultured mouse and human stem cells to generate both embryonic and extra-embryonic tissues. Their technique, described in the journal Cell on April 6, 2017, could yield new insights into mammalian development that lead to better disease modeling, drug discovery and even tissue regeneration.

In a study published in Cell Stem Cell in April 2017, senior author Juan Carlos Izpisua Belmonte and collaborators have shed light on a longstanding question about what leads to variation in stem cells by comparing induced pluripotent stem cells (iPSCs) derived from identical twins. Even iPSCs made from the cells of twins, they found, have important differences, suggesting that not all variation between iPSC lines is rooted in genetics, since the twins have identical genes. The findings help scientists better understand the processes involved in reprogramming cells and the differences between iPSCs and ESCs (embryonic stem cells). The work could also lead to improvements in the way iPSCs are being used for research and therapeutics.

The lab of Juan Carlos Izpisua Belmonte has developed a novel technology to correct disease-causing aberrations in the chemical tags on DNA that affect how genes are expressed. These types of chemical modifications, collectively referred to as the epigenome, are increasingly being considered as important as the genome itself in development and disease. In the May 4, 2017, issue of Science the team described how they used the tool to model mutations in tags associated with colon cancer and to restore the proper tags in stem cells derived from people with Angelman syndrome.