Explore Follistatin-315, a circulating activin-binding protein studied for muscle growth, fibrosis control, and tissue repair.
The moderated mass amounts below are retained for comparison. Near-duplicates, mix-dependent volumes and device markings are excluded. This is educational source context, not a protocol or recommendation.
Recorded example with no verified study backing; shown for amount literacy only.
Recorded example with no verified study backing; shown for amount literacy only.
Only mcg or mg amounts are retained. The calculator derives mL, syringe units or pen clicks from the current vial strength, water volume and device.
No clinical amount or schedule is inferred from this material. Source verification is pending, and every displayed amount remains educational context rather than guidance.
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What published studies and recent community write-ups report about amounts, timing and course length. 4 clinical, 2 preclinical and 2 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical4 rows | |||||
| Becker muscular dystrophy gene transfer, phase 1/2a6 adults with Becker muscular dystrophy, in two cohorts of 3 | 3 x 10^11 vg/kg per leg (cohort 1) or 6 x 10^11 vg/kg per leg (cohort 2) of AAV1.CMV.FS344 | Single administration, given as direct injections into both quadriceps | Intramuscular | One procedure, followed for up to 2 yearsNot applicable; gene transfer is a single event | Molecular Therapy (PubMed Central)2015 |
| Two patients gained 58 m and 125 m on the 6-minute walk test and one did not change in the lower-dose cohort; in the higher-dose cohort two gained 108 m and 29 m and one did not improve. Biopsies showed less endomysial fibrosis, less central nucleation and fibre hypertrophy, most at the high dose, with no adverse effects reported. The vector carries FS344, which becomes FST-315 once the signal peptide is cleaved, so this is the closest human evidence for this isoform and it is gene transfer rather than injected protein. | |||||
| Sporadic inclusion body myositis gene transfer6 ambulatory adults with sporadic inclusion body myositis, compared with 8 untreated patients matched for age, sex and baseline | 6 x 10^11 vg/kg of rAAV1.CMV.huFS344 | Single administration to the quadriceps of both legs | Intramuscular | One procedure, with an exercise regimen alongside and outcomes annualized to a median 1 yearNot applicable | Molecular Therapy (PubMed)2017 |
| Walking distance improved by 56.0 m per year in the treated group against a 25.8 m per year decline in the untreated comparison group. Four of six treated patients gained 58 to 153 m while two gained only 5 to 23 m, and the authors note that more advanced disease with established muscle loss remained a problem. Every participant also followed an exercise programme, so the treatment effect cannot be isolated. | |||||
| Registered three-cohort dose escalation15 patients with Becker muscular dystrophy or sporadic inclusion body myositis | 2 x 10^11 vg/kg to one quadriceps, then 3 x 10^11 and 6 x 10^11 vg/kg per quadriceps bilaterally | Single administration per participant | Intramuscular | One procedure, with safety as the primary endpoint over 2 yearsNot applicable | ClinicalTrials.gov2012 |
| This is the registration behind the published Becker and inclusion body myositis reports, run at Nationwide Children's Hospital from 2012 and completed in October 2017. Its listed primary outcome is safety at 2 years, the enrolment is 15 across the three cohorts, and no results have been posted to the registry. | |||||
| Plasmid injection aimed at raising circulating FST-31543 adult volunteers of both sexes, aged 23-88, median age 46 | 50 mcg of FST-344 plasmid complexed with linear polyethyleneimine in 400 microlitres of saline | Single injection | Subcutaneous, into abdominal fat | One injection, with measurements at baseline and 3 monthsNone described | Minicircle Inc. (company preprint, medRxiv)2024 |
| The stated design was to transfect abdominal fat cells with the 344 variant so they would secrete FST-315 into the blood. Serum follistatin rose from a mean 8.58 ng/mL to 24.03 ng/mL at three months, fat-free mass rose 1.96 lb on average, body fat fell 0.87% and extrinsic epigenetic age fell 7.10 years, with no severe adverse effects reported. This was a single-arm, company-run study with no control group, a three-month window and a preprint that has not been peer reviewed, and a minority of participants had a large rise in LDL cholesterol. | |||||
| Preclinical2 rows | |||||
| Primate gene transfer, the study behind the human trialsCynomolgus macaque monkeys | 1 x 10^13 vector genomes in total per treatment, given as three injections into one quadriceps | Single administration | Intramuscular | One procedure, with long-term follow-up of transgene expressionNot applicable | Science Translational Medicine (PubMed)2009 |
| Muscle size and strength rose markedly and durably in the injected leg, and long-term expression produced no abnormal changes in the morphology or function of key organs, which is the safety argument that carried the approach into people. PubMed records an erratum to this paper published by Science Translational Medicine in August 2026. | |||||
| Engineered FST-315 fusion protein in mice, repeated dosingC57BL/6 wild-type mice and mdx dystrophic mice | 1-50 mg/kg in the wild-type dose range; 3, 10 and 30 mg/kg in the mdx studies | Twice weekly | Intravenous or subcutaneous | 4 weeks in wild-type mice, 12 weeks in the mdx studiesNone described | Skeletal Muscle (PubMed Central)2018 |
| Muscle mass and fibre size rose dose dependently, grip strength and tetanic force improved, and necrosis, inflammation and fibrosis markers fell at 10 and 30 mg/kg, with larger effects than an anti-myostatin antibody at the same dose. This is the only repeated-dose protein schedule published for a follistatin-based molecule, and it required an engineered Fc fusion at milligram-per-kilogram doses rather than native protein. | |||||
| Community-reported2 rows | |||||
| Reported research range with reconstitution math | 100 mcg as a conservative start, 200 mcg as the common figure, 300 mcg as the reported ceiling | Once daily | Subcutaneous | About 10-30 days per blockNot specified beyond ending the block | Community resource2026 |
| This chart models a 1 mg vial in 1 mL of bacteriostatic water, giving 10 mcg per unit on a U-100 syringe, and steps 100 mcg in week one to 200 mcg in weeks two and three. It states plainly that no human trial has injected recombinant follistatin protein, that the only human therapy used AAV gene transfer at vector rather than protein doses, and that the figures are an educational model with no established ceiling. | |||||
| Lower reported band tied to the half-life argument | 50-200 mcg | Once daily, which the page attributes to a circulating half-life of about 90 minutes | Subcutaneous | Not specifiedNot specified | Community resource2026 |
| This reference page lists a narrower 50-200 mcg band and grades its own claims: binding to myostatin and activin A as strong evidence, hypertrophy as moderate and rodent-only, and the Becker trial as preliminary and not evidence for this isoform because it delivered FS344 by AAV rather than FST-315 protein. It also notes that no dedicated pharmacokinetic study of FST-315 was found to confirm the 90-minute figure. | |||||
Community charts describe 100 mcg once daily subcutaneously as the conservative starting figure, drawn as 10 units from a 1 mg vial reconstituted in 1 mL of bacteriostatic water. Nothing is measured at this stage and no study supports the route.
The commonly quoted figure rises to 200 mcg once daily, with 300 mcg listed as the reported ceiling. Daily injection is justified on the grounds that the protein clears from circulation within hours, a point every one of these pages concedes is unmeasured for this product.
Blocks are described as running 10 to 30 days rather than months, and the stated reason is arithmetic rather than biology: 12 weeks at 200 mcg a day would consume roughly 17 vials of 1 mg. Guides that discuss stopping give no biomarker or endpoint to check.
Human dosing on record is a single event, not a course: one intramuscular AAV administration at 3 x 10^11 or 6 x 10^11 vg/kg per leg, with outcomes measured over 1 to 2 years afterwards. No repeated-dose schedule of follistatin protein has been tested in a person by any route.
Plus 3 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
Follistatin-315 is the mature, circulating form of human follistatin: the product of the FST gene's 344-residue precursor (UniProt P19883, computed mass 38,007 daltons) once its 29-residue signal peptide is removed, leaving a glycosylated 315-residue chain. It binds activin A and myostatin and keeps them off the activin type IIB receptor, and because its acidic C-terminal tail stops it from sticking to cell-surface heparan sulfate it stays in the blood instead of on tissue, which is the practical difference between it and the shorter FST-288 isoform. PubChem holds no compound record for any follistatin isoform, so there is no molecular formula, CAS number, InChIKey or molar mass to report here; PubChem indexes the protein only under accession P19883, and the identifier quoted on older pages (178101631) is a PubChem substance number rather than a compound record for follistatin. No human study has ever injected recombinant follistatin protein of either isoform: the human record is intramuscular AAV gene transfer of the FS344 variant, which is processed to FST-315 after secretion, one company-run plasmid study, and a 26-subject dermatology trial of a cell-derived complex containing follistatin alongside KGF and VEGF, where hair shaft thickness rose 6.3% and terminal hair density 20.6% at 12 weeks. It is approved nowhere, is sold as a research chemical, and myostatin-pathway inhibitors are on the WADA prohibited list.
These themes organize the educational information currently available. Individual claims remain under source review and are not treatment claims.
Myostatin inhibition and performance insights
Autoimmune, pulmonary, and radiotherapy studies
Endothelial recovery and renal protection
Disease monitoring and synthetic derivatives
Research considerations
Available context is organized without assigning unsupported study models or evidence grades.
Myostatin inhibition and performance insights
Autoimmune, pulmonary, and radiotherapy studies
These amount records are independent from vial strength, reconstitution volume and measuring device. A recorded source is not the same as study backing, and these values are not recommendations.
1 link carried over from the earlier page, awaiting verification.