Follistatin 344 is a recombinant version of natural follistatin, which is produced by multiple tissues in humans and other animals. Follistatin is made up of 344 amino acids and acts as a myostatin inhibitor supplement. Myostatin is a negative regulator of muscle growth found in the blood and produced in muscle cells. Studies have shown considerable promise for enhancing muscle mass and strength in animal models and follistatin is being studied for its therapeutic potential in human muscle diseases . Several myostatin-binding proteins capable of regulating myostatin have been found, but follistatin is an especially potent blocker of myostatin and has even shown muscle-enhancing effects beyond those predicted by myostatin inhibition . Myostatin signalling acts via the activin receptor type IIB on muscle cells, triggering a cascade of biological signalling events inside the cell . These events cause changes in the expression of specific genes that regulate muscle growth [4, 5]. Blocking myostatin with follistatin will therefore increase muscle mass and inhibiting this pathway results in increased muscle growth and increased muscle strength. These effects have been shown in mice, where blocking the activity of myostatin led to increased skeletal muscle mass without any serious side effects . This method was also found to be safe and durable in a subsequent clinical trial . Pronounced and durable increases in muscle size and strength have also been seen in non-human primate studies . A recent human clinical trial delivered follistatin 344 to six patients with a muscle wasting disease called Becker muscular dystrophy . The follistatin protein was administered by direct bilateral intramuscular quadriceps injections and clinical benefits were observed in patients receiving follistatin 344. These patients showed reduced muscle fibrosis, reduced central nucleation and more normal muscle fibre size distribution. The treatment also increased muscle growth at the higher doses when muscle size was compared before and after treatment with follistatin 344. Follistatin 344 is usually administered as a genetic therapy in human and animal studies, which provides high and sustained levels of follistatin protein. However, as a reconstituted protein it can be administered intramuscularly at either 100 mcg, 200 mcg or 300 mcg per day and should be cycled over 10 days with a 3-month break. Follistatin 344 should be administered locally to the muscle that you wish to build and the daily dose can be split over several individual muscles. Once dissolved in BAC water the protein is stable for one week at 4-8�C. Follistatin 344 has shown minimal side effects even when tested at high and prolonged doses during genetic therapies in animal and human studies. However, mild side effects may include muscle soreness or swelling post-workout, as well as temporarily weakened ligaments and tendons. References 1. Kota, J., et al., Follistatin Gene Delivery Enhances Muscle Growth and Strength in Nonhuman Primates. Science translational medicine, 2009. 1(6): p. 6ra15-6ra15. 2. Lee, S.J., Quadrupling muscle mass in mice by targeting TGF-beta signaling pathways. PLoS One, 2007. 2(8): p. e789. 3. Rebbapragada, A., et al., Myostatin signals through a transforming growth factor beta-like signaling pathway to block adipogenesis. Mol Cell Biol, 2003. 23(20): p. 7230-42. 4. Langley, B., et al., Myostatin inhibits myoblast differentiation by down-regulating MyoD expression. J Biol Chem, 2002. 277(51): p. 49831-40. 5. Massague, J. and D. Wotton, Transcriptional control by the TGF-beta/Smad signaling system. Embo j, 2000. 19(8): p. 1745-54. 6. Bogdanovich, S., et al., Functional improvement of dystrophic muscle by myostatin blockade. Nature, 2002. 420(6914): p. 418-21. 7. Wagner, K.R., et al., A phase I/IItrial of MYO-029 in adult subjects with muscular dystrophy. Ann Neurol, 2008. 63(5): p. 561-71. 8. Mendell, J.R., et al., A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy. Mol Ther, 2015. 23(1): p. 192-201.