The FDA’s recent approval of the first CRISPR-Cas9–based gene therapy has marked a major milestone in biomedicine, validating genome editing as a promising treatment strategy for disorders like sickle cell disease, muscular dystrophy, and certain cancers.

CRISPR-Cas9, often likened to “molecular scissors,” allows scientists to cut DNA at targeted sites to snip, repair, or replace genes. But despite its power, Cas9 poses a critical safety risk: the active enzyme can linger in cells and cause unintended DNA breaks—so-called off-target effects—which may trigger harmful mutations in healthy genes.

Now, researchers in the labs of Professor Ronald T. Raines (MIT Department of Chemistry) and Professor Amit Choudhary (Harvard Medical School) have engineered a precise way to turn Cas9 off after its job is done—significantly reducing off-target effects and improving the clinical safety of gene editing. Their findings are detailed in a new paper published this week in the Proceedings of the National Academy of Sciences (PNAS).

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Researchers used cells that glow green due to a green fluorescent protein (GFP) gene. If Cas9 is working, it disrupts the GFP gene and the cells stop glowing. If LFN-Acr blocks Cas9, the cells keep glowing. These images depict cells in different conditions: some with active Cas9 (which stopped the green glow), some with Cas9 and LFN-Acr (glow stayed on).

Image courtesy of the researchers.

Uppsala University Hospital-led investigators report that gene-edited donor islet cells survived 12 weeks inside a man with long-standing type 1 diabetes without any immunosuppressive medication.

Intensive insulin therapy can delay complications and improve life expectancy. Early-onset type 1 diabetes remains linked to reduced quality of life, serious cardiovascular risk, and shortened lifespan. Toxicity from lifelong immune suppression also drives morbidity and mortality in organ recipients.

In the study, “Survival of Transplanted Allogeneic Beta Cells with No Immunosuppression,” published in the New England Journal of Medicine, researchers conducted a first-in-human open-label trial to test whether hypoimmune-engineered islet cells could evade rejection.

Chinese scientists have developed a gene editing technology capable of precisely manipulating large DNA segments ranging from thousands to millions of base pairs in both plant and animal cells, marking a significant advance in the field of life sciences.

The research team from the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences announced the new technology in a study published online Monday in the journal Cell.

The method, called PCE (Programmable Chromosomal Engineering), combines three innovative techniques to enable programmable editing of large chromosome segments. In lab tests, researchers successfully inserted an 18,800-base-pair DNA fragment, replaced a 5,000-base-pair sequence, inverted a 12-million-base-pair chromosomal region, deleted a 4-million-base-pair segment, and even relocated entire chromosomes.