OHSU Researchers Produce First Genetically Modified Monkey: FAQ

 

 

What exactly did your research group do to produce ANDi?


ANDi, inserted DNA spelled backward, is the first genetically modified rhesus monkey. He was produced using techniques commonly utilized for genetic modification in animals and human gene therapy. DNA was introduced to monkey eggs through a neutralized retroviral vector, which carried a reporter gene, GFP (green fluorescent protein). After DNA introduction, eggs were fertilized by intracytoplasmic sperm injection (ICSI). A total of 20 embryo transfers led to five pregnancies and three healthy male offspring, including ANDi. The presence of the reporter gene in ANDi has been verified by DNA analysis.

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What is the purpose of this research?


The purpose of this research is to optimize techniques to produce genetically modified nonhuman primates as disease models. This advancement will help doctors and scientists accelerate the study of gene and cell therapies as well as vaccines and drugs to treat human diseases.

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What are the benefits of your research findings?


This research is encouraging because it could accelerate the work of scientists searching for cures to hundreds of human diseases. With monkey disease models, science can greatly advance the understanding of treatments for a broad range of diseases. In the past investigators have used mouse models to study and conquer human diseases. However, mice are not always effective test subjects for human illness therapies because some human diseases do not surface when genetically introduced into mice. As research moves to more complex diseases, such as cancer, Alzheimer's and AIDS, many scientists see the need for a model that is closer to humans.

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How long have you been working on this technique?


The research began two years ago as one of several initiatives. However, its potential importance to advancing cure development has made it one of our top priorities.

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What is the next step?


The birth of ANDi proves that the use of a neutralized vector can lead to genetic modification of nonhuman primates. Our next step would be to verify the efficiency of these results with additional offspring. Subsequently, we will aim at targeting the exact location of the foreign gene location, known as gene targeting. At some point in the future this technique will be used to develop disease models.

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What is ANDi's condition and what are the plans for his future?


ANDi is a normal, energetic, healthy monkey. He is being raised in group housing with his two siblings. We will monitor ANDi's growth and development to determine the efficacy of our protocols.

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What happened to the other two pregnancies that did not result in offspring?


One resulted in a blighted pregnancy, which means no embryo implantation occurred. The other resulted in a set of twins, which are uncommon in rhesus and thus unfortunately miscarried. The twin fetuses both carried the reporter gene and expressed the green protein.

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What is the long-term plan for monkeys that are transgenic?


At the Oregon Regional Primate Research Center, our transgenic offspring are housed in dedicated primate group housing, and monitored for normal growth and development. If this technique is determined ideal for producing disease monkey models, an expert panel will be convened determine which diseases and disorders should be the first targeted.

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What was the oversight process for this research?


Both university and national authorities provide oversight for this research. The National Institutes of Health carefully reviewed the initial research proposal as part of the funding request. Even before that point, however, it was reviewed and approved by OHSU animal welfare and biosafety committees. As the research advanced, at our request, OHSU convened a special panel, including ethicists, doctors, scientists and regulatory officials. In addition, we have had many follow-up meetings with OHSU's biosafety committee ensuring the health and safety of the animals.

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Did you actually produce a green monkey?


In the case of ANDi, we have confirmed the presence of the GFP reporter gene, as well as the gene's RNA, but have not yet detected the green protein in the areas of ANDi that are accessible. The existence of the RNA indicates that the gene is activated, but is not yet producing the protein, or producing the protein at a level undetectable at this time. Similar work by Anthony Chan, Ph.D., D.V.M., in cattle showed that GFP detection may be delayed until later in ANDi's development.

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What are the benefits of inserting a green protein into a monkey?


The green fluorescent protein (GFP) gene is naturally occurring in jellyfish. It is safe, easily detectable and is currently used in numerous research projects. In our case, it is merely a marker to determine if our transgenic methods are efficient and effective.

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Could the fact that some of the animals were stillborn be linked to the GFP DNA insertion or to the procedure used to do this?


Twins rarely survive in rhesus macaques. However, it is not impossible that the insertion of the GFP gene into a vital genetic region led to the loss of pregnancy. Analyses currently ARE underway to determine exactly where the GFP gene inserted into the stillborns' DNA.

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Could this technique be used for genetic enhancement?


The purpose of this research is to produce relevant animal models of the diseases that still plague us today. The technique itself is still in its infancy, and we have an enormous amount to learn and optimize before it is readily used in animal models. At some point in the future it is conceivable that others may attempt this technique to enhance humans. Thus, we encourage the current and future national and international conversations as to regulations of this and similar techniques to limit their use to disease research and treatments.

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How does this work differ from the research conducted approximately one year ago by your lab?


In December 1999 Chan and colleagues reported in Molecular Human Reproduction the attempt to introduce the GFP gene to monkey embryos through a different technique, Transgen-ICSI. In that work, monkey sperm were coated with the GFP gene and then used to fertilize monkey eggs through intracytoplasmic sperm injection (ICSI). Although no transgenic offspring were produced, the work demonstrated that Transgen-ICSI is a technique that may lead to transgenic offspring in the future.

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Why are nonhuman primate disease models required when past research has been conducted with mice?


Mice have been invaluable to further the understanding of the genetic basis for a variety of human diseases and disorders. However, some human diseases are not accurately mimicked in mouse models. In addition, it is preferable to perfect treatments in animal models more closely related to humans. Nonhuman primates will more accurately duplicate disease features seen in humans as well as provide invaluable information as to the efficacy of proposed treatments.

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Will this research be beneficial to the Human Genome Project?


Absolutely. The Human Genome Project provides the sequence of our DNA, or in other words describes the building blocks of life. However, we still need to determine how these building blocks function, how they interact, and how they are dependent on each other. In addition, we need to determine how environmental influences affect these building blocks.

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Why did you use a virus to introduce GFP?


We are all familiar with viruses in our lives, which sometimes cause a variety of illnesses. However, scientists and physicians currently utilize modified viruses to both produce transgenic animals for disease models and use similar viruses to treat diseases in humans. Viruses have the unique ability to introduce DNA into cells; thus scientists take advantage of this ability to introduce genetic information to produce relevant animal models or clinical treatments to patients. These viruses have been modified with no ability to replicate or cause disease.

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Why the name ANDi?


In our work, we used a retrovirus to introduce the reporter gene to the monkey. A retrovirus is an RNA virus, which must be translated into DNA before recombining with the monkey's DNA. Through the translation process, the RNA is reverse transcribed and then inserted into the monkey's DNA. Inserted reverse DNA led to the name ANDi.

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