Lluís Montoliu

A team from the Netherlands has successfully edited pathogenic mutations in mitochondrial DNA in human cells, changes in DNA that cause disease, according to research published in PLoS Biology. The authors used a genetic tool known as a base editor. Until now, techniques derived from CRISPR have made it possible to correct mutations in nuclear DNA, and new techniques are being developed that allow mitochondrial DNA to be edited.

A team from the Children's Hospital of Philadelphia and Penn Medicine (United States) has successfully treated a baby diagnosed with a rare genetic disorder using personalised CRISPR gene editing therapy. The baby, known only by the initials KJ, was born with a rare metabolic disease known as severe carbamoyl phosphate synthetase 1 (CPS1) deficiency. After spending the first months of his life in hospital on a very restrictive diet, KJ received the first dose of his tailored therapy in February 2025, between six and seven months of age. The treatment, which is being used for the first time for this type of disorder, was administered safely, and the baby is now growing well and improving. The case is detailed in a study published by The New England Journal of Medicine (NEJM).

Colossal Biosciences has announced the creation of genetically modified mice with characteristics reminiscent of the fur of extinct mammoths, such as fur colour, texture and thickness. The non-peer-reviewed results were shared today in the BioRXiv prepublication repository.

A team of researchers has used embryonic stem cell engineering to create a bipaternal mouse - a mouse with two male parents - that lived to adulthood. Their results, published in the journal Cell Stem Cell, show how targeting a particular set of genes involved in reproduction enabled this breakthrough in unisexual reproduction in mammals.

Two articles published in Nature describe a new genome editing technique that enables the insertion, inversion, or deletion of long DNA sequences at specific positions in the genome. This is a one-step approach that could offer a simpler method for genome editing in the future. The authors describe a technique to create reprogrammable recombinases—key enzymes in genetic recombination. These enzymes are guided by RNA, which acts as a bridge, directing the recombinase to target sites and facilitating predetermined editing.

Five out of ten potential treatments move from animal studies to human studies; four to randomised controlled clinical trials; and one in 20 moves on to approval by regulatory agencies, an analysis estimates. Concordance between positive results in animals and in clinical studies is 86%, according to the study, published in PLoS Biology, which pools the findings of 122 published studies on 54 different human diseases.  

Two independent research teams have managed to regenerate brain circuits in mice using neurons cultivated from rat stem cells. Today, both studies were published in the journal Cell. The research, in which chimeras of different species were generated, delve into how brain tissue forms and present new opportunities for restoring lost brain function due to diseases and aging.

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.