Encoded in human genes should be everything they need for survival. But every so often our DNA breaks from the mold and a mutation occurs — a one in 100,000 chance, according to Wendell McKenzie, professor of genetics.

Mutations can be good or bad, but it is the bad ones that plague us. Diseases and syndromes such as Huntington’s, Alzheimer’s and Marfan’s have detrimental effects on human life, but usually cannot be diagnosed until a patient is middle aged and already had children — potentially passing on the tiny links that could unravel their lives.

Huntington’s disease is an example that spares no one with the mutated gene. Huntington’s causes brain cells to breakdown, leading to uncontrolled movements, loss of intellectual faculties and emotional disturbance. And currently there is no treatment.

But Dr. Jose Estrada, research assistant for the Departments of Molecular and Biomedical Sciences and Animal Science, is hoping his work will help to change these people’s fate; one little cloned pig at a time.

“If we can develop an animal for that disease, we can see how it evolves,” he said. “[We could] test treatments for that disease, which is very difficult in humans because we have to save the life of the patient, we can not use them as test subjects.”

Estrada is working for Dr. Jorge Piedrahita in the College of Veterinary Medicine’s new Center for Comparative Medicine and Translation Research and for Dr. Bob Petter’s lab in animal science.

Together, they are all working under a collaborative agreement to produce transgenic pigs, Estrada said.

As the head scientist in the cloning lab, Estrada works long days in a small research room at the College of Veterinary Medicine. He began at the University five and half years ago and began on the cloning project three years ago.

In this relatively short period of time, the swine cloning has flourished with an 80-percent litter rate, which is the percent of embryo transfers that give litters, according to Estrada — a rate that is close to the pregnancy rate under normal farm conditions, which is 95 percent.

Over the past year about 120 cloned pigs have been born at the University. And their attributions to science are not only for helping scientists conquer disease. The clones can also improve livestock quality, keep endangered animals from extinction and make advances in xeno-transplantation.

How to make a clone

The idea of cloning is to produce one individual from another without reproduction, Estrada said.

“We take somatic cells from anywhere,” he said. “They are already programed something specific, so in this case we put that cell in an oocyte, which is collected and aspirated.”

Cloning begins with an immature cell from the ovary, called an oocyte.

McKenzie identifies cloning as a simple procedure that attempts to mimic fertilization. Rather then mixing an egg and a sperm, each normally contributing half of the genetic information through sexual intercourse or in vitro fertilization, cloning uses somatic cells that provide all of the DNA through ennucleation.

The somatic cells from fetuses are grown in vitro and transfected with the gene that is intended to be expressed in the clone. The oocyte and the cell are then fused by electrical pulses, called electrofusion.

“Once the two cells are integrated into one cell, the oocytes are activated,” Estrada said. “The embryo is ready to be transfered into the recipient pig.”

The recipient pig is in the first day of her estrous cycle, so she is synchronized with the embryo. Scientists transfer 100 embryos into one pig, and on average, six piglets are born per litter.

“Which is very good,” Estrada added. “After the litter is born, we run DNA tests to confirm that the newborn carries the transgene [genotyping] that was used for the cell transfection.”

Putting clones to use

Livestock quality, animal extinction, biomodels and xeno-transplantation are all problems examined by scientists through cloning.

In agriculture, clones offer a possible solution to issues such as meat quality and waste management.

“You can genetically select better organisms,” John Harman, a senior in biological sciences, said. “If you want to produce them for meat or selective breeding, you wouldn’t have to worry about breeding so much, you would have the perfect organism.”

One application for selecting better organisms has to do with environment.

Estrada emphasized the importance of creating more environmentally friendly pig waste because one of the main criticisms of the pork industry is pollution.

Clones can also be used as a way of preserving nature. Estrada described how scientists have used cloning to save species close to extinction because the animals cannot reproduce fast enough to keep numbers high enough for survival.

Scientists then use similar domesticated species’ oocytes.

“For example, scientists used a domesticated cat’s oocyte for an endangered wild cat’s clone,” Estrada said.

Animals that cannot reproduce naturally, such as mules, can also reproduce by this approach, according to Estrada.

Swine biomodels offer a new approach to learning about disease in animals that are more similar to humans.

“Swine are phylogenetically closer to humans than mice and offer an excellent alternative biomedical model to study the etiology of human disease,” Steven Bischoff, a doctoral student in comparative biomedical sciences, said.

Most diseases are modeled in mice by either feeding the mice mutagens and then looking for a phenotype, or they will take out a gene from the genotype and see how it affects the mice, according to Bischoff.

Shengdar Tsai, a doctoral student in functional genomics, identified the interest in transgenic pigs as also size-related.

“There is a real interest in a large animal model,” he said. “That is one of the things a lot of pharmaceutical companies want because they have trials where the drugs work great on mice, and then they try to translate that to humans and it just doesn’t work.”

Now that the entire human genome map is sequenced, scientists can identify one gene involved in one disease, according to Estrada. He identified Huntington’s as an example.

“For Huntington’s we could take that gene and insert it in a pig so it has Huntington’s disease,” he said.

By doing that, scientists will be able to track the progression of the disease and test treatments.

But that is only a part of a clone’s medical ability. Xeno-transplantation is the transplanting of organs from one species to another, which is important because pig hearts are a comparable size to human hearts, according to Estrada.

Human-to-human heart transplantation is hard enough, but transferring from one species to another creates an even greater likelihood for the organs to be rejected. So to make the organs a better match, Estrada said that scientists can study clones to find a transplant that would be less likely to cause rejection.

The applications for cloning have only just begun, and Estrada acknowledges that there are many more in the future.

“What you can imagine is possible,” he said. “It is a very wide area.”