> Colossal’s dire wolf work took a less invasive approach, isolating cells not from a tissue sample of a donor gray wolf, but from its blood. The cells they sel

> Colossal’s dire wolf work took a less invasive approach, isolating cells not from a tissue sample of a donor gray wolf, but from its blood. The cells they selected are known as endothelial progenitor cells (EPCs), which form the lining of blood vessels. The scientists then rewrote the 14 key genes in the cell’s nucleus to match those of the dire wolf; no ancient dire wolf DNA was actually spliced into the gray wolf’s genome. The edited nucleus was then transferred into a denucleated ovum. The scientists produced 45 engineered ova, which were allowed to develop into embryos in the lab. Those embryos were inserted into the wombs of two surrogate hound mixes, chosen mostly for their overall health and, not insignificantly, their size, since they’d be giving birth to large pups. In each mother, one embryo took hold and proceeded to a full-term pregnancy. (No dogs experienced a miscarriage or stillbirth.) On Oct. 1, 2024, the surrogates birthed Romulus and Remus. A few months later, Colossal repeated the procedure with another clutch of embryos and another surrogate mother. On Jan. 30, 2025, that dog gave birth to Khaleesi. The process seems to have dictated this. They needed an easy surrogate, a dog, and wolves required no need of introducing anything new into the genome, it's "just" reactivating what is already there.