Ace-031, also known as ACVR2B, is a soluble form of activin type IIB receptor, which is an inhibitor of myostatin and other naturally occurring proteins that limit muscle growth. This compound was genetically developed to bind to myostatin before it can attach to its receptor and halt muscle growth. The two Biopharma companies that worked on this compound are Acceleron and Shire.
Myostatin is a hormone in our bodies that signals muscles to stop growing and replicating. Therefore, when you inhibit, or block myostatin, muscles will be able to grow bigger and you will become stronger. Imagine being able to block myostatin and continue to grow muscle indefinitely – you would be able to become like a super hero.
Myostatin and its related gene were discovered in 1997. Genetics doctors Dr. Se-Jin Lee and Alexandra McPherron found out that the cause of abnormal extra-huge muscles of the two breeds of cattle, Belgian Blue and Piedmontese, had the damaged myostatin genes (this muscle feature of these cattle breeds is known as “double muscling”).
They unnaturally produced a strain of mutant mice that lacked myostatin. As a result, these mutant mice had approximately twice as much musculature as normal mice. These mice were subsequently named as “mighty mice”. Mutation of the moystatin gene results in an inability of the body to produce its own myostatin and then myostatin cannot inhibit the muscle growth.
Afterwards, these mutations started to be used for breeding new muscular cattle breeds. Genetic mutations of the myostatic gene were observed also in a breed of racing dogs closely related to greyhounds (Whippet). Individuals with the myostatin gene mutation were apparently more capable runners and they featured different overall appearance. It is not disputed that animals lacking myostatin or animals treated with doping substances that block the myostatin activity (such as, e.g. Follistatin) have significantly larger muscles. Even a 20% reduction in moystatin levels has a great effect on the muscle development.
In 2004, a German boy was diagnosed with a mutation in both copies of the myostatin-producing gene, making him considerably stronger than his peers. As the boy is growing, he is becoming stronger than his peers. The lack of myostatine has not yet reflected on his overall health condition. Doctors will have to continue to observe him closely just in case, he could develop hypertrophy of the vital organs (e.g. heart hypertrophy). His mother, a former female sprinter, has a mutation only in one copy of the gene. People with a mutation in both copies of the MSTN gene in each cell (homozygotes) have significantly increased muscle mass and strength than common people; therefore, they appear stronger than the standard level. People with a mutation in one copy of the MSTN gene in each cell (heterozygotes) also have increased muscle bulk, but to a lesser degree.
In 2013, Acceleron Pharma published results of a human study, in which 48 healthy women aged from 45-75 were given a single injection containing 0.02, 0.05, 0.1, 0.3, 1 or 3 mg ACE-031 per kg bodyweight. The single injection did lead to muscle growth. The 3 mg/kg dose led to an increase in muscle volume by 5 percent, it boosted lean body mass by 3 percent and additionally, it seemed to also reduce fat mass. The injection reduces also the leptin concentration. This would suggest that ACE-031 decreases actively the fat mass level. ACE-031 remained in their body through several weeks after administration and the half-life was estimated to 10-15 days.
The myostatin inhibition leads to muscular hyperplasia (growth of new muscle fibres) and significantly larger hypertrophy (growth and volume increase of already existing muscle fibres). From this point of view, those products truly have a great future potential for sportsmen who aim at the increase of muscle growth.
In one human study, overweight females were given a one time dose of 250 milligrams (mg) of Ace 031. As a result, after a month their muscles in the thighs grew over a pound. What’s more, their lean body mass increased 3%, which is quite a result.
However, in another study done on young boys with muscle dystrophy, the test subjects ended up having gum and nose bleeding. Unfortunately, both Shire and Acceleron eventually abandoned their partnership, and since 2013 no further development has been conducted. Since then, you can find Ace-031 being sold as research chemicals on various websites, but no trusted brand has come out selling it yet.
In the different studies that were conducted, subjects experienced a reduction in leptin concentration and boosted adiponectin, which is a ‘good fat’ hormone. Hence, perhaps Ace-031 does really contribute to fat loss. Another study showed an increase in alkaline phosphatase in the blood and reduced collagen telopeptide; this may mean it also helps strengthening the bones.
In a study with females, the concentration of FSH (follicle-stimulating hormone) dropped significantly, and there is no explanation as to why. Thus, it appears that there are some side effects, and we do not know if the same would occur in men. However, we know that in cattle, farmers refuse to use Ace-031 to ‘beef up’ their stock because of infertility concerns. Therefore, perhaps that connection has to do with mother nature not allowing an ultra muscular being to reproduce?
Even a slight decrease in myostatin would result in a dramatic increase in muscle mass, but it would also mean you would need more food to feed those muscles as well. Another problem is that our heart would continue growing, since it is a muscle, and over time this could lead to heart failure due to having this organ work too hard. Besides, in the long run, an unhealthy heart will definitely hurt your gains. Furthermore, you could also argue that your stomach would grow as well because you can’t control what muscles get affected or not. For instance, certain muscles might grow bigger than others. For example, you can have a 50% increase in your glutes and only 20% in your delts.
Dosage and administration
During the studies done on Ace-031, where rats were injected, they were given 10mg/kg. Hence, to match those types of figures, a normal sized adult bodybuilder would have to use about 1 gram a month, all things being equal. This means that if you were to use a gram it would cost you tens of thousands of dollars to get in that amount each month.
According to bodybuilders who have been able to get Ace-031, dosages seem to range from 1-3mg per kg of body weight every 1-2 weeks. At $50 per mg, this would cost a 200 pound user around $10,000. Besides, considering the sketchy world of peptide companies, if you were to spend that kind of money, you better make sure it is a legitimate product you were purchasing.