GDF-11

GDF-11 is a TGF-beta family ligand secreted as a latent propeptide complex and activated by proteolysis; the mature signalling molecule is a 109-residue monomer that functions as a homodimer of roughly 25 kDa. It binds ActRIIA/ActRIIB and ALK4/5/7 to phosphorylate SMAD2/3. Its mature domain is about 90% identical to myostatin (GDF-8), which is both mechanistically important and the source of most of the controversy — many early assays could not distinguish the two, and the reported age-related decline in GDF-11 may have been an artefact of that cross-reactivity. The 2013 Harvard work reported that restoring GDF-11 reversed cardiac hypertrophy and improved muscle and neurogenesis in aged mice. In 2015 a Novartis group reported the opposite: GDF-11 increases with age and inhibits muscle regeneration. The field has not fully resolved this, and it is the main reason GDF-11 sits under a cloud rather than at the centre of longevity practice.

Targets: ActRIIA / ActRIIB, ALK4/5/7, SMAD2/3, Myostatin-shared signalling axis

• · Rodent work used roughly 0.1 mg/kg/day intraperitoneally, but given that the direction of GDF-11's effect on muscle is actively disputed, quoting a human dose would be irresponsible. There is no human data of any kind.

Work out your exact syringe units →

• commonUnknown in humans— No human exposure data.
• uncommonMuscle wasting / impaired muscle regeneration— Not hypothetical — this is what the Novartis rodent work reported at higher doses, and it follows directly from the myostatin-like signalling.
• rareCachexia at high exposure— Reported in rodent studies at supraphysiological doses.

• Anyone whose goal is muscle retention or growth — the plausible risk here runs directly against that aim.
• Sarcopenia or frailty.
• Pregnancy and breastfeeding — GDF-11 is a developmental patterning factor with no safety data.

• conflictfollistatin-344 — Follistatin inhibits GDF-11 and myostatin; the two directly oppose each other.
• conflictigf-1-lr3 — Opposing effects on muscle anabolism.

• · Lean mass by DEXA if anyone is actually using this, given the muscle-wasting signal.
• · There is no validated assay that cleanly distinguishes GDF-11 from myostatin in routine practice, which is a core problem with the whole compound.

Not approved anywhere; a research reagent.

• Loffredo et al. 2013, Cell — growth differentiation factor 11 as a circulating factor reversing age-related cardiac hypertrophy (preclinical)
• Egerman et al. 2015, Cell Metabolism — GDF11 increases with age and inhibits skeletal muscle regeneration (preclinical)

GDF-11 signals through the activin type II receptors ActRIIA and ActRIIB, recruits type I receptors ALK4, ALK5 or ALK7, and phosphorylates SMAD2/3. That is the myostatin pathway. The mature domains of GDF-11 and myostatin are about 90% identical, and that similarity is not a footnote — it is the reason the field is in the state it is in. Most of the antibodies used in the early studies could not distinguish the two proteins, which means the celebrated 2013 finding that GDF-11 declines with age was measuring something that may substantially have been myostatin or an aggregate of both. In 2013 the Harvard group reported that restoring GDF-11 in old mice reversed age-related cardiac hypertrophy, and the 2014 Science follow-up reported improved skeletal muscle regeneration and neurogenesis, and this became the molecular story of the young-blood parabiosis experiments. Then in 2015 a Novartis group published in Cell Metabolism that GDF-11 increases with age and inhibits skeletal muscle regeneration, and that higher exposures caused muscle wasting and cachexia — the exact opposite conclusion, from a group with better assays. A 2016 Circulation Research paper from the original camp reported that circulating GDF11/8 does decline with age, using a targeted assay. A 2020 Proteomics paper developed a mass-spectrometry method specifically to distinguish GDF8 from GDF11 in serum, which tells you how unresolved the measurement problem still was seven years after the original claim. The field has not converged. What follows from the pharmacology is unambiguous even if the direction of the ageing claim is not: a ligand that is 90% identical to myostatin and signals through the same SMAD2/3 axis should be expected to do myostatin-like things to muscle, and the reported cachexia at high exposure is consistent with that rather than surprising.

The framing error is the whole problem. GDF-11 entered the popular longevity conversation as 'the young blood factor', and people buy it on that basis without knowing that the central claim was contradicted within two years by a better-equipped group, and that the assay problem means the original age-decline observation may have been measuring myostatin. What you are actually buying is a recombinant ligand that is 90% identical to myostatin in its mature domain and signals through the same receptors. The documented rodent consequence at higher exposure is impaired muscle regeneration and, at supraphysiological doses, cachexia. That is not a theoretical risk derived from mechanism — it is a published result. Beyond that: this is a recombinant growth factor supplied in micrograms, often needing a carrier protein for stability, and product identity and activity are unverifiable by the buyer. There is no human dose, no human pharmacokinetics and no human data of any kind. The rodent work used roughly 0.1 mg/kg/day intraperitoneally, and quoting a human equivalent for a compound whose direction of effect is actively disputed would be irresponsible. And there is no assay available to you that cleanly separates GDF-11 from myostatin, so you cannot even monitor what you are doing.

• ActRIIA and ActRIIB (activin type II receptors) — High affinity, comparable to myostatin. Precise constants vary by assay and are not consistently reported across studies.

  Primary binding event. These are the same receptors myostatin uses, which is why the two ligands are functionally difficult to separate.

• ALK4 / ALK5 / ALK7 (type I receptors) — Recruited into the complex after type II binding.

  Kinase activity that phosphorylates SMAD2/3.

• SMAD2/3 — Not a binding target — downstream substrate.

  Transcriptional programme that in skeletal muscle is broadly catabolic and anti-regenerative, which is why myostatin inhibition builds muscle and myostatin-like signalling does not.

• Follistatin (endogenous antagonist) — Follistatin binds and neutralises both GDF-11 and myostatin.

  Relevant practically: follistatin-based products directly oppose GDF-11, so running both is pharmacologically self-cancelling.

Unknown in humans — nothing has been administered in any published human study. In the rodent work, cardiac and muscle phenotypes changed over roughly four weeks of daily dosing, in both the positive and the negative studies. The practically relevant timeline is the harm one: if muscle regeneration is being impaired, you would expect it to show as declining training performance and lean mass over weeks rather than days, which is exactly the timescale on which people attribute it to something else.

Two direct conflicts, both mechanistically unambiguous. Follistatin-344 and any follistatin-based product exists to neutralise GDF-11 and myostatin — running them together means each is undoing the other, and if the follistatin product works you have effectively bought GDF-11 to throw away. IGF-1 LR3 and other anabolic agents push muscle in the opposite direction from SMAD2/3 signalling, so the combination is a tug of war with an unknown winner. More broadly: if muscle retention is any part of your goals, GDF-11 is not a compound to add to your stack under any framing, because the documented rodent harm and the myostatin-shared pharmacology both point the same way. There is no established synergy for GDF-11 with anything, because there is no established effect to be synergistic with.

GDF-11 is the compound on this page where the gap between reputation and evidence runs in the opposite direction from everything else. Epitalon and MOTS-c are under-evidenced but at least uncontradicted; GDF-11 is under-evidenced and actively contradicted by high-quality work. Against follistatin and myostatin inhibitors, which are the compounds most people in this space actually want: those aim to reduce signalling through exactly the pathway GDF-11 activates, so if you want more muscle you want the opposite of this. Against klotho, the other large protein on this page: klotho at least has a consistent literature and a striking primate result, however impractical the product situation is. Against doing nothing: for anyone whose goals include muscle retention, doing nothing is clearly better than the plausible downside here. GDF-11 is on this site because it is historically important to the longevity conversation and because people still encounter it, not because the evidence supports using it.

Not estimable and deliberately left null. Recombinant GDF-11 is a research reagent sold by the microgram at reagent pricing, and there is no established human dose against which a monthly cost could be computed. Quoting one would imply a protocol that does not exist.

• ?The direction of GDF-11's effect on skeletal muscle is genuinely disputed in the primary literature and has not been resolved.
• ?Whether circulating GDF-11 rises or falls with age is disputed, and the early measurements were confounded by antibody cross-reactivity with myostatin.
• ?No pharmacokinetic data exist in any species for administered recombinant GDF-11.
• ?No human has been dosed in any published study; there is no human dose, safety data or efficacy data.
• ?Molecular weight is not stated in the Core record; the ~25 kDa figure for the mature homodimer is the commonly cited approximation and was not verified against a primary source in this session.
• ?The mature-domain amino acid sequence was not resolved in this session and is therefore not stated.
• ?No assay available outside specialist mass-spectrometry laboratories reliably distinguishes GDF-11 from myostatin, so monitoring exposure is not practically possible.
• ?Whether GDF-11 crosses the blood-brain barrier is unknown, which matters given the neurogenesis claims in the 2014 work.
• ?Cost cannot be estimated because no dose or protocol exists.

• Growth differentiation factor 11 is a circulating factor that reverses age-related cardiac hypertrophy Loffredo FS, Steinhauser ML, Jay SM, Gannon J, Pancoast JR, Yalamanchi P, Sinha M, Dall'Osso C, Khong D, Shadrach JL, Miller CM, Singer BS, Stewart A, Psychogios N, Gerszten RE, Hartigan AJ, Kim MJ, Serwold T, Wagers AJ, Lee RT, Cell, 2013 · PMID 23663781

  The original claim — GDF-11 as the young-blood factor reversing cardiac hypertrophy in aged mice. Everything positive said about GDF-11 traces here, and the age-decline measurement in this work is exactly what the assay controversy calls into question.

• Restoring systemic GDF11 levels reverses age-related dysfunction in mouse skeletal muscle Sinha M, Jang YC, Oh J, Khong D, Wu EY, Manohar R, Miller C, Regalado SG, Loffredo FS, Pancoast JR, Hirshman MF, Lebowitz J, Shadrach JL, Cerletti M, Kim MJ, Serwold T, Goodyear LJ, Rosner B, Lee RT, Wagers AJ, Science, 2014 · PMID 24797481

  The skeletal muscle follow-up that extended the claim from heart to muscle. This is the paper the 2015 Novartis work most directly contradicts.

• GDF11 increases with age and inhibits skeletal muscle regeneration Egerman MA, Cadena SM, Gilbert JA, et al., Cell Metabolism, 2015 · PMID 26001423

  The contradiction. Opposite direction of age change and opposite effect on muscle regeneration, from a group with better assay discrimination between GDF11 and myostatin. If you read only one paper before considering this compound, read this one.

• Circulating growth differentiation factor 11/8 levels decline with age Poggioli T, Vujic A, Yang P, Macias-Trevino C, Uygur A, Loffredo FS, Pancoast JR, Cho M, Goldstein J, Tandias RM, Gonzalez E, Walker RG, Thompson TB, Wagers AJ, Fong YW, Lee RT, Circulation Research, 2016 · PMID 26489925

  The original camp's response on the measurement question, reporting a decline in combined GDF11/8. Note the combined analyte — that framing is itself an admission of how hard the two are to separate.

• Targeted approach to distinguish and determine absolute levels of GDF8 and GDF11 in mouse serum Camparini L, Kollipara L, Sinagra G, Loffredo FS, Sickmann A, Shevchuk O, Proteomics, 2020 · PMID 32104967

  A mass-spectrometry method developed specifically to separate GDF8 from GDF11 — seven years after the original claim. The existence of this paper is the clearest statement of how unresolved the measurement problem was.

• The role of GDF11 in aging and skeletal muscle, cardiac and bone homeostasis Egerman MA, Glass DJ, Critical Reviews in Biochemistry and Molecular Biology, 2019 · PMID 31144559

  The best single review of the whole controversy, written from the sceptical side. Read alongside a review from the original camp if you want both perspectives.