History of Pet Cloning

How did animal cloning, especially pet cloning develop step by step? In fact, it can be intuitively understood as the constant cloning of more complex animals.

The Origin of the Story

The idea of animal cloning was first proposed by German embryologist Hans Spemann in 1938. In 1952, scientists used frogs to carry out cloning experiments, and continued with various animals for cloning technology research. However, limited by many conditions, only the cloning of non-mammals could be focused on. But within a few decades, animals such as starfish, frogs, and carps have been cloned one after another.

Scientists soon turned to mammal cloning. The first successful nuclear transfer of embryonic cells from a rabbit happened in 1975. However, in order for the egg to complete its development, it needs to be implanted in the rabbit's uterus. Since the technology was still in the early stages at that time, the last step was not finished. By 1984, in vitro fertilization had been well developed, and the first lamb cloned from the embryo was born to a surrogate mother. In 1987, a cow was cloned in the same way.

Dolly the Sheep

Although cloning technology continues to evolve, the real breakthrough was the birth of Dolly. Before Dolly, all successful mammalian clones, and the most successful clones of any animal, could only be done using cells from early embryos. Dolly changed everything. The nucleus from the udder cell of an adult sheep was transferred to the enucleated egg cell. The new egg received a brief electric shock to stimulate cell division. The embryo was implanted into a surrogate sheep, and in July 1996, Dolly, the world's first somatic cloned sheep, was born in Edinburgh, Scotland. Her name comes from the country music queen Dolly Parton. The cloned sheep's birth immediately attracted global attention, with people calling her the most famous animal in the world. This also adds to the evidence that mammals can be cloned.

Fig.1 Dolly the sheep- display at the National Museum of Scotland.

Fig 2 The cloned cat CC. (Stubbs E C, and Campbell S K. 2011)

Cat Cloning

After Dolly, scientists began to clone other animals, such as mice, cows, pigs, goats, rabbits, and cats, etc. In 2001, a cat named CC-Copy Cat, was successfully cloned. It is the crystallization of somatic cell cloning, which was cloned by American scientists using a cumulus cell from the mother's body. The cumulus cells provide nutrients for the growing eggs in the ovary. However, CC is the lucky one out of 188. The researchers tried a total of 188 times and produced 82 embryos, but only one cat became pregnant successfully, and this pregnancy only gave birth to one kitten. The birth of CC marked the opening of the pet cloning market.

Fig 3 The three cloned dogs at 2 months of age. (Kim M J, et al. 2017)

Dog Cloning

Compared with cats, cloned dogs face more severe challenges. Due to the complex reproductive physiology, the process of in vitro culture and somatic cell cloning of dogs is very difficult. In 2005, after several failed attempts, researchers used somatic cell nuclear transfer (SCNT) technology to clone two Afghan hounds. One of the cloned dogs, Snuppy, lived for ten years, and it was described as "a revolutionary breakthrough in dog cloning." It is reported that the Snuppy research team originally produced 1,095 recombinant embryos in this process, and implanted an average of 5-12 embryos into 123 surrogate dogs, trying to achieve the goal of pregnancy. In the end, only three were successfully conceived. And of the puppies that were born, only Snuppy was lucky enough to survive at five years of age.

In 2009, a new technology for cloning dogs with stem cells from adipose tissue was developed. This technology greatly increased the success rate of cloning, and the world's first commercial cloned dogs were successfully cloned.

Today, animal cloning has become a mature and well-established technology, and an increasing numberof pet owners choose to continue the life of their beloved pets through cloning. BioVenic can provide you with the best pet cloning services.

References 

1. Stubbs E C, and Campbell S K. "Why Are Cloned Cats Not Identical, Implications for Pet Cloning and Public Perception.". (2011)
2. Kim M J, et al. "Birth of clones of the world's first cloned dog." Scientific reports. (2017), 7.1: 1-4.