Lluís Montoliu

Epigenetic editing is a technique that aims to alter gene expression without the need to modify the DNA sequence, as gene editing techniques do. In this way, Italian researchers have succeeded in silencing the PCSK9 gene in mice, thereby reducing cholesterol levels by half for at least a year. According to the authors, and assuming further evaluation is needed, their platform "could lay the foundations for the development of this type of therapy". The results are published in the journal Nature.

A team of Chinese researchers report today in the journal Nature Communications the successful cloning of a rhesus monkey, with a healthy placenta, which survived for more than two years. According to the authors, this could improve the efficiency of the monkey cloning process, which so far is very low. Previously, different teams have cloned more mammalian species, including 'Dolly the sheep' and another species of macaque (Macaca fascicularis).

A team led by the Princess Máxima Pediatric Oncology Center and the Hubrecht Institute (The Netherlands) has generated small 3D brain models--known as organoids--from human fetal brain tissue. Until now, these brain organoids-which attempt to resemble real organs on a miniature scale-were grown in the laboratory using pluripotent or embryonic stem cells. The new technique, published in the journal Cell, allows regions of brain tissue to self-organize into three-dimensional brain structures. The authors used these organoids and the CRISPR-Cas9 tool to simulate the development of one type of brain tumor, glioblastoma, and see how it responded to different drugs.

The European Medicines Agency (EMA) has recommended approval of the first drug in the European Union to use the CRISPR/Cas9 gene-editing technique. The drug, Casgevy, is indicated for the treatment of two rare inherited diseases, beta thalassaemia and sickle cell disease (sickle cell anaemia), caused by genetic mutations that affect the production or function of haemoglobin, the oxygen-carrying protein in red blood cells. Both conditions are debilitating and potentially fatal. The EMA opinion will be sent to the European Commission for a decision on an EU-wide marketing authorisation.

A Chinese research team has reported the birth of a crab-eating macaque that is a chimera: an animal generated from the mixing of embryonic cells from two different individuals; in this case, from the same species, according to the journal Cell. Until now, this type of chimera had only been developed with rodents. This is the first time it has been achieved in non-human primates.

Berna Sozen's lab at Yale University has announced a new milestone in the competition to create synthetic embryos: their human pluripotent stem cells self-organise into structures that mimic embryonic development on days 9-14 after fertilisation and include extra-embryonic tissues. Their achievement is published in Nature at the same time as another similar study, that of Magdalena Zernicka-Goetz, who a fortnight ago previewed her stem cell-derived human embryo model to The Guardian, sparking a controversy with Jacob Hanna, author of a preprint showing that she had achieved true synthetic embryos. 

The latest episode of competition between research groups working on the same topic, a very common situation in science, should not distract us from the actual achievement: synthetic human embryos, in the laboratory, made from stem cells, up to a post-implantation stage. Now, we must decide what status or condition we will grant to these synthetic embryos. Once again, science is leaping forward and testing the limits of the laws, posing new ethical challenges for us to solve. 

Chinese researchers have succeeded in developing macaque embryo-like structures from embryonic stem cells. They have also managed to implant them in the uterus of female macaque monkeys and develop a hormonal response similar to that of a gestation, although they have only survived for about a week. According to the authors, whose research is published in Cell Stem Cell, these models could be used to improve our understanding of embryonic development and to investigate the causes of some early miscarriages.

In January 2013, two laboratories demonstrated that CRISPR tools could be used to edit genes in human cells. Ten years later, the first patients are already benefiting from the molecular scissors to overcome incurable diseases. This week in Science, one of the pioneers of CRISPR, Nobel laureate Jennifer Doudna, summarises the history of these tools, without forgetting that it all began thirty years ago with the findings of Francis Mojica in the Santa Pola salt flats.