Mice, manipulating DNA and muscle-building viruses: The next big scam or the future of bodybuilding?
by Paul Cribb, B.H.Sci HMSAST Director of Research
Hot on the heels of the myostatin scam, more research into genetically enhanced muscle growth has caught the attention of athletes across the world. You may have read some reports in the media of research by Dr. H. Lee Sweeney and colleagues that have recently shown that genetic manipulation combined with resistance training can dramatically accelerate muscle growth.
Dr. Sweeney heads the Physiology department at the University of Pennsylvania. The main interest of these scientists is in muscle regeneration from injury and disease. As part of this current research study, these scientists investigated the effects of transferring growth-factor genes into muscle cells to accelerate muscle growth during exercise. And, they have been successful.
Using recombinant DNA technology, the researchers created a piece of DNA that codes for Insulin Growth Factor-1 (IGF-1); the muscle growth stimulator. DNA is the genetic code the body uses to construct proteins within the body. Imbedded within our DNA is a code that creates every protein that the body needs, whether it is an enzyme for breaking down food, a component of muscle tissue or a hormone. Recombinant technology “re-combines” the components of DNA to produce a blueprint for a protein that the scientists may want to examine; in this case, the DNA code was for IGF-1. Despite the recent media interest, the research involving the insertion of new DNA into muscles was first published in 1998.
Most bodybuilders are aware that IGF-1 is a growth factor that is essential to building muscle. Certain isotopes of IGF-1 actually remain “dormant” in muscle cells until the cell is “stimulated” (damaged) by high overload resistance training. Then, the active IGF-1 is “unlocked” and springs into action to establish new satellite cells that results in a bigger, thicker, stronger muscle fiber.
However, the fascinating kink in the story behind this research is the way the IGF-1 is “artificially” stimulated within the muscle cells of the mice. Getting the artificial DNA into the muscle cells is the stuff science-fiction writer’s dream of.
The IGF-1 DNA is actually placed inside the shell of an artificial virus. This virus is used to infect the muscle cells; it attaches to the surface of the cell and deposits its DNA into the inner membrane, pretty much the same way a normal virus works. The natural defense systems within the cell cannot distinguish one piece of DNA from another, so the IGF-1-stimulating DNA is incorporated into the protein structure. The artificial virus (containing the IGF-1-DNA) does not contain any other information, only the blueprint for IGF-1 production. Once imbedded into proteins within the cell, the IGF-1-containing DNA tricks the cell into producing the components necessary for bioactive IGF-1.
In this study, after eight weeks the mice that were subjected to resistance exercise showed a 23.3% increase in muscle mass, whereas the mice treated with the artificially induced IGF-I showed a 14.8% increase in muscle mass, without performing exercise. However, the combination of resistance training and treatment with the virus containing IGF-1 DNA produced double the rate of muscle growth as compared to either treatment alone. The findings were published in the March issue this year of Journal of Applied Physiology and the implications from these results make the myostatin research look puny.
Most mammals, including mice and men, lose up to a third of their muscle mass and strength as they age. It is not clear why this happens, but evidence suggests that declines in the production and activity of growth hormone (GH) and insulin-like growth factors such as IGF-1. Aside from making super mice, this research would essentially cure many degenerative diseases such as muscular dystrophy and hypertrophic cardiomyopathy. Invalids would literally rise from their wheelchairs and walk. The potential applications are staggering, and positive results have already been documented in dystrophic mice. The artificially induced IGF-1 procedure completely reversed this fatal wasting disease.
Could the same process be used to assist elite athletes to achieve greater strength with less training? Probably. The potential for abuse is right there alongside the potential for good. Additionally, by directly infecting the muscle, there would be no indication or proof that the athlete is utilizing technology; it would not be detectable with the current blood or urine analyses. The only possible means to detect this sort of drug abuse lay in DNA testing. Based on this research it would still have to be specific to the muscle (or group) used in a particular sport. Essentially, this all adds up to one big nightmare for officials and organizations that sanction drug-tested sporting events.
However, these genetic alterations do have a down side. The subsequent growth of muscle tissue from the recombinant DNA IGF-1 treatment is only region specific. The impact of one portion of the body growing at a vastly different rate to other segments is anyone’s guess. Long term consequences of this gene therapy are also hampered by the fact that mice have a relatively short life span. Therefore, how the human body would react to artificially injected genes, is best left up to the imagination of Steven Spielberg’s special effects crew. Particularly, the potential impact on the immune system and the body’s own intricate hormonal cascade is mind boggling.
There is no doubt that some form of this genetic therapy will be the savior of thousands of clinically ill people in the near future. However, long before this technology is available on the black market, I suspect a slew of bogus “DNA IGF-1-activating” supplements are going to flood the retail sports supplement market, and it will be done in much the same unscrupulous manner as the myostatin blockers. And we all know how effective myostatin-blockers turned out to be!
The bodybuilding supplement market place is probably going to be avalanched with a pile of bogus, crap DNA-IGF-1-activating herbal extracts, pills and protein powders. Just like the myostatin blockers, these supplements will be marketed with a ton of thick, slick scientific spin-doctoring as “the holy grail” of muscle gains. However, now you’ve got the real facts, before the scam has even started. Consumers beware, you have been warned.
Lee, Sukho, Elisabeth R. Barton, H. Lee Sweeney, and Roger P. Farrar. Viral expression of insulin-like growth factor-I enhances. muscle hypertrophy in resistance-trained rats. J Appl Physiol 96: 1097–1104, 2004.
Barton-Davis ER, Shoturma DI, Musaro A, Rosenthal N, and Sweeney HL. Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function. Proc Natl Acad Sci USA 95: 15603-15607, 1998
Barton ER, Morris L, Musaro A, Rosenthal N, and Sweeney HL. Muscle-specific expression of insulin-like growth factor I counters muscle decline in mdx mice. J Cell Biol 157: 137-148, 2002.