Update on Follistatin, Myostatin, and selective androgen receptor modulators

Researchers at Nationwide Children’s Hospital in Ohio have gained funding to carry out a clinical trial injecting a virus carrying a gene called follistatin which stimulates muscle growth

Jerry Mendell M.D. and Brian Kaspar PhD have been awarded a US$600,000 grant by the US charity Parent Project Muscular Dystrophy. The money will be used to manufacture the clinical grade viruses and conduct the clinical trial which is due to start in 2011. The gene therapy approach has been successfully tested in monkeys and involves blocking the protein myostatin with follistatin. Myostatin is a protein produced by muscle cells that prevents the muscles from growing bigger and stronger


They will inject a modified virus (vector) carrying the gene for the muscle growth-stimulating protein follistatin into the quadriceps muscles of volunteers with Becker muscular dystrophy and sporadic inclusion body myositis. The goal of the study is to verify that the procedure is safe and to document any increase in quadriceps muscle size and function. People with these diseases have overall muscle weakness but with particular weakness of the quadriceps muscle, which is important for standing and sitting. Preliminary studies in mice with muscular dystrophy and in non-human primates demonstrated that follistatin delivered in this manner can cause significant increases in the size of injected muscles. Improvements in the strength of the mice and non-human primates were documented.

Follistatin on Monkeys

The researchers just injected the gene follistatin (FS344) directly into the monkeys right thigh muscles. It has been shown that follistatin can block myostatin, a molecule that down-regulates muscle growth, but strengthens tendons. Eight weeks after the injection the circumference of the monkeys right thigh muscles, had on average gone up 15 percent compared with the left thigh. A study done on two of the monkeys showed that muscle strength in the right leg was increased by respectively 12 and 36 per cent compared to the untreated leg.

SARM a potentially safer steroid

Selective androgen receptor modulators or SARMs are a novel class of androgen receptor ligands. They are intended to have the same kind of effects as androgenic drugs like anabolic steroids but be much more selective in their action. None of the SARMs yet developed are truly selective for anabolic effects in muscle or bone tissues without producing any androgenic effects in tissues such as the prostate gland, however several non-steroidal androgens show a ratio of anabolic to androgenic effects of greater than 3:1 and up to as much as 10:1, compared to testosterone which has a ratio of 1:1.

Information from Kaizer Coutore (trainer and bodybuilder) and some of my own research.

Ostarine which is a SARM(Selective Androgen Receptor Modulator) and is currently in Human clinical trials by GTx Inc. and also another SARM under the codename BMS-564,929 which is being developed by Bristol-Myers Squibb. Only the substance known as “SARMs S4” (Andarine) has made it to the market, and is being used by a limited number of pro and amateur bodybuilders.

Ostarine at wikipedia

GTx held an End of Phase II meeting with the United States Food and Drug Administration (FDA) in December 2010. GTx expects to initiate early in the third quarter of 2011, following additional input from FDA, a pivotal Phase III clinical trial evaluating Ostarine for the prevention and treatment of muscle wasting in patients with non-small cell lung cancer.

The next 5-10 years will see many substances come out and some might be good replacements for Anabolic steroids. These drugs will be available through the black market for pro and amateur athletes alike, with unprecedented anabolic effects and close to no negative side effects.

There are various stories online of people claiming to already by using Ostarine and to being able to but it.

Kaizer Coutore listed some online sites where SARMs can be purchased.

The Follistatin (myostatin blocking) gene therapy clinical trial only costs $600,000, so it seems likely that some athletes could already be experimenting with it. Someone who wanted to experiment with it could probably spend a lot less than the $600,000 used in a clinical trial with multiple controls and other steps that are not needed for personal use.

1 thought on “Update on Follistatin, Myostatin, and selective androgen receptor modulators”

Comments are closed.