In 1903 the term “clon” was created by plant physiologist Herbert J. Webber describing the propagation of new plants using buds, cuttings, or bulbs. Decades later, the spelling changed to “clone” and came to refer to creating genetically identical copies of any species, animal, plant, microorganism, or human. The cloning method chosen by a cultivator is usually the one that dramatically increases the survival rate of the plants or trees, reduces their time to grow from youth to a harvestable adult, improves yields, guarantees the plant quality remains consistent, and increases profitability. Yet, there are negatives to all the above methods of plant cloning. One huge problem is the lack of genetic diversity otherwise found in nature which creates variety and strengths in plants often not discovered until society needs them. Since clones all have the same genetic makeup of the original plant, they have a narrow spectrum of resistance, and diseases that harm a single cloned plant potentially can destroy an entire crop. Also, cloning can easily lead to increased commercialization and monocropping of fewer specific plants which also reduces biodiversity in agriculture.
Grapes, blueberries, bananas, apples, cherries, and fruits in general sold in US food supermarkets are grown on cloned trees or plants through the use of cuttings. Clones create stable and predictable fruit quality. The navel orange was a natural mutation discovered in 1820 in Brazil. The Granny Smith Apple was also a natural mutation that occurred in Australia in 1868. Today, both these kinds of fruit trees are clones propagated using cuttings, genetically identical to those original trees from the 1800s.
The use of plant cuttings has been in use since the Middle Ages in European and Chinese agriculture. Grafting plants, also a cloning technique, was documented around 300BC in Greece. The Tissue culture cloning method, also known as micropropagation, grows plant cells in agar jelly or a broth growth medium. This method was first used in the 1950s to produce orchids and in the 1970s on other plants.
Tissue culture cloning labs have grown African oil palm, plantain, pine, banana, date, eggplant, jojoba, pineapple, rubber tree, cassava, yam, sweet potato, and tomato.
Farmers and home gardeners have used cutting and grafting techniques for centuries. There are dozens of YouTube videos and on plant and tree cloning including the tissue culture method.
Cloning is a common theme in sci-fi literature and movies. However, it almost always deals with the concept of human cloning. Books such as Brave New World, Cloud Atlas, and the Kiln People describe future worlds where human clones are common. However, today the practice of cloning a human is officially banned in 46 of the world’s 195 nations. The United Nations adopted a non-binding resolution banning cloning in 2005 called the Declaration on Human Cloning. The US has no national policy banning human cloning but does have regulations limiting funding and procedures related to human cloning. Although there are scientists who support the concept of human reproductive cloning, most scientists and medical research organizations formally oppose it because clones could be abused and it would create unforeseen problems in society. In 2013 the US Supreme Court ruled that human genes cannot be patented because naturally occurring genes are not a new intellectual property. However, the Court ruled DNA assembled in a laboratory was eligible for patenting because human-altered DNA chains are not found in nature. Currently, there seems to be enough opposition to human cloning to keep it from becoming a commodity business, like that of selling animals and plants, because the international community of scientists, governments, and ethicists cannot accept the idea of manufacturing disposable humans or human slaves.
There are 3 types of cloning in use today that involve using human or animal DNA – gene cloning, reproductive cloning, and therapeutic cloning. The research most related to human cloning is called therapeutic cloning which is still mostly experimental and theoretical. Because human cloning is illegal, therapeutic cloning focuses almost entirely on stem cell research. Embryonic stem cell research seeks to discover potential cures for inherited and chronic human diseases, traumatic injuries, and to regenerate organs. Embryonic stem cell research requires embryos that have been grown from human eggs fertilized in vitro at fertilization labs. The stem cells are donated with informed consent from donors. However, critics point out that cloned stem cells are often weaker than the original and mutations can occur in cells that are transferred to a patient. A report from Grand View Research, an international research company, estimates that by 2027 worldwide stem cell revenues will reach $17.9 billion. It is estimated by some critics that for therapeutic cloning to become a viable treatment to cure diseases, at least 1 million human eggs per year will be needed. Egg collecting is painful for donors and extremely expensive. Only 400,000 human eggs have been gathered by US laboratories over the last two decades so the standard embryonic stem cell cloning process cannot be considered practical at this time. However, in 2018 Japanese scientists did not use human donor eggs but instead changed human blood cells into stem cells. The scientists then modified the stem cells into human eggs. These eggs were too immature to be fertilized to make a baby. In September 2019, researchers at the University of Michigan began making human-like embryos from stem cells. Whether these lab embryos could someday be modified and made to grow into a healthy human is unknown. Since then the University of Michigan lab has made hundreds of these embryos. Researchers say the world is getting closer to being capable of creating humans in a lab. Many scientists are opposed to therapeutic cloning because it will eventually lead to creating human clones.
There are various restrictions on the use of human embryos. Future Science, a journal for clinical medicine and biosciences published an article in August 2020 on the policies of the top 22 research-intensive nations concerning human embryonic research. The article stated there is a ‘14-day rule’ in most countries conducting human embryo research. In practice, this rule requires that fertilized human embryos will not be grown in vitro (outside the human organism, in a test tube) for longer than 14 days. After 14 days, the embryo is to be destroyed. On the 14th day, an embryo develops what is called a primitive streak, after which the embryo begins its process of cell differentiation and creating a human body. This is the bioethical reason for the 14-day limit on the use of embryos in labs. At this time, no human clones have been documented although several discredited scientists in South Korea have said they cloned embryo cells. The Canadian company Conaid has claimed to have cloned 13 people but has been unable to provide any evidence to prove it.
But if there are no human clones, are there any other kinds of clones in existence today? Yes, microorganisms, animals, and plants. It is as if they are hidden. The average person is not aware of the clones or their offspring.
Gene cloning, or DNA cloning, is a commonly used process that creates duplicates of genes, or segments of DNA. With this method, one or more genes or DNA fragments from a gene are taken from various microorganisms, animals, humans, or plants and inserted into a bit of DNA called a plasmid. The next step is joining all the parts together. This is called recombinant DNA, a molecule constructed of DNA from multiple sources.
Next, the plasmid is placed into bacteria. As these modified bacteria grow in the lab, they reproduce and pass on the modified plasmid to their offspring. What are some common uses for DNA cloning? The pharmaceutical industry uses it to create billions of bacteria that act as factories to produce specific medicines such as insulin, human growth hormone, and tPA hormone (for treating strokes and blood clots). Doctors use DNA cloning in FDA-approved gene therapy for those born with genetic disorders such as B-cell acute lymphoblastic leukemia. Then there is gene analysis. Here, laboratory biologists build new recombinant types of genes to learn how genes work in an insect, animal, etc. Unfortunately, DNA cloning, and genetic engineering have also been used to create bioweapons by at least 17 nations, including China, Russia, and the United States.
Reproductive cloning has been used since 2001 by pet lovers, like singer Barbra Streisand, to make clones of their pets. Viagen Pets, in Cedar Park, Texas, is the world leader in pet cloning services. They encourage owners to order a Biopsy Kit and collect a sample of the pet’s tissue while the pet is still alive to make sure the cells are viable to use for cloning. At the cost of $1,600, they will cryopreserve (safely freeze) the cells for the time when the owner decides to order a clone of their pet. The cost of cloning a dog is $50,000, a cat is $35,000, and a horse, $85,000. Once a cloned embryo is prepared, it is placed in a surrogate mother to grow until it is birthed naturally. The gestation period and nursing process of a cloned pet is no different than that of a regular pet of the same species. The cloned pet will have the exact genetic makeup as the original, will tend to have a normal lifespan, but may have different colors and shapes of its markings. Although the traits of the clone will probably be similar to the original pet, the clone will develop its own personality. To date, Viagen has cloned over 1000 pets.
Trans Ova Genetics has been in the enhanced livestock breeding business for four decades. It is also the USA leader in livestock cloning and has successfully cloned thousands of animals. The clones of pigs, cattle, goats, and sheep are used as prime breed stock for offspring that produce superior meat. Trans Ova Genetics produces cloned embryos and implants them into surrogate mothers and birthed at their company farm. The babies are raised on-site and delivered to the customer after weaning. The cost to clone a cow is minimally $15,000, and $4,000 to clone a sow. The FDA has ruled that the offspring of a clone is not a clone — so it may be used for conventional meat and dairy production. Globally, the number of cloned pigs and cattle is about 6,000. How many offspring of cloned livestock are annually sold for meat is uncertain.
For 40 years, the cells of an endangered horse species, Przewalski’s horse, otherwise known as the Mongolian Wild Horse, were stored at the San Diego Zoo. This is the only true wild horse and is extinct in the wild. Today only about 2,000 survive in zoos and managed wildlife habitats. San Diego Zoo’s Our Frozen Zoo division contains the biggest genetic material collection of endangered and rare animals on the planet. It is comprised of over 10,000 living cell cultures, sperm, and embryos representing nearly 1,000 specific animals.
Cloning wild animals is mostly done through interspecies cloning. For Przewalski’s horse, the DNA from a frozen non-reproductive Przewalski’s horse cell was removed and then placed into a domestic horse egg cell which had its DNA removed. A domestic horse was the surrogate mother for the cloned embryo and gave birth to a healthy foal in August 2020. This foal had the same genetic composition as the wild Przewalski’s horse that “donated” its cells to San Diego Zoo four decades ago. To date, the cloned endangered species that have survived to adulthood are the white-tailed deer, mouflon, bighorn sheep, African wildcat, banteng (a species of wild Asian cattle), wolf, Spanish ribbed newt, Northern leopard frog, and Japanese pond frog.
Cannabis is still mostly grown from seeds, but USA companies are increasingly using cuttings to speed up the propagation time and improve the quality of harvested plants. Conception Nurseries, a cannabis plant supplier to growers, exclusively uses tissue culture to grow genetically unique plants. Research on Cannabis is showing it a likely treatment for patients with multiple sclerosis, chronic pain, and epilepsy. It is estimated that cannabis may help with as many as 172 medical conditions which leads some experts to predict the medical sales of cannabis will exceed the recreational market in a few years. The USA cannabis market may reach $67 billion this year and $130 billion by 2024 according to Marijuana Business Factbook.
It appears that in one form or another, cloning is here to stay, at least in terms of growing plants and microorganisms. So far, cloning of animals has produced a few thousand domesticated and a handful of endangered wild animals. As far as creating the first human clone goes, the opposition is strong, and it appears will be so for the foreseeable future.