Growth Differentiation Factor 11 is a Circulating Factor that Reverses Age-Related Cardiac Hypertrophy

The study addresses whether age-related cardiac hypertrophy, a major contributor to diastolic heart failure in the elderly, is driven and potentially reversible by circulating systemic factors. With diastolic heart failure remaining without targeted therapies and aging populations increasing disease burden, the authors leveraged heterochronic parabiosis to test if exposure of old mice to a young circulatory milieu can reverse cardiac hypertrophy. They hypothesized that blood-borne factors present in young animals mediate anti-hypertrophic effects, making cardiac aging at least partly hormonal and reversible.

Prior work shows systemic milieu profoundly influences tissue aging. Heterochronic parabiosis has demonstrated rejuvenation of aged skeletal muscle satellite cell function and regeneration, and conversely inhibition of myogenesis and neurogenesis in young mice exposed to old blood. Cardiac aging is characterized by left ventricular hypertrophy and diastolic dysfunction; clinical progress in diastolic heart failure lags behind systolic heart failure. This background supports testing whether circulating factors modulate cardiac aging and hypertrophy.

• Animal model: C57BL/6 mice; young ~2 months; old 21–23 months; both sexes tested. Parabiosis established between pairs: heterochronic (young-old, HP) and isochronic (young-young, Y-IP; old-old, O-IP). Pairs maintained for 4 or 10 weeks.
• Verification of cross-circulation: congenic CD45.1/CD45.2 markers with flow cytometry of blood/spleen cells (>90% pairs confirmed; 40–50% partner-derived splenocytes typical). For fully isogenic CD45.2 pairs, chimerism inferred from model precedent.
• Controls for non-circulatory effects: sham parabiosis (surgical joining without shared circulation via silicone disk separation) in hetero- and isochronic configurations for 4 weeks.
• Hemodynamics: Noninvasive systolic blood pressure and heart rate via modified tail-cuff enabling simultaneous measurement in both partners; serial measurements up to 10 weeks. Terminal intra-arterial micromanometer catheterization to measure mean arterial pressure. Serum angiotensin II and aldosterone measured by ELISA.
• Cardiac morphology: Heart weight normalized to tibia length (mg/mm). Histology: PAS staining of LV; blinded morphometric analysis of cardiomyocyte cross-sectional area (100–200 myocytes/animal; 5 sections/heart).
• Molecular assays: Cardiac mRNA levels of ANP, BNP, SERCA-2 by qRT-PCR.
• Discovery of candidate factors: Metabolomic profiling (69 amino acids/amines) and lipidomics (142 lipids across 9 classes) on plasma; aptamer-based proteomics (SOMAscan) of plasma from 10 young and 10 old mice (1001 proteins). Western blot validation of GDF11 in plasma and tissue expression analyses (mRNA/protein) across organs including spleen.
• In vitro assays: Neonatal rat cardiomyocyte hypertrophy assay measuring 3H-leucine incorporation after phenylephrine (50 µM) with/without recombinant GDF11 (rGDF11) or myostatin (0.5, 5, 50 nM). Human iPSC-derived cardiomyocytes assessed for pathway activation (pSMAD2/3) and Forkhead (FoxO) phosphorylation after 15 min stimulation with rGDF11 or myostatin (50 nM).
• In vivo rGDF11 therapy: Dose-finding identified 0.1 mg/kg i.p. as effective to raise plasma GDF11 ~24 h. Randomized, blinded, vehicle-controlled study: 23-month-old female mice received daily i.p. rGDF11 (0.1 mg/kg) or saline for 30 days; endpoints: heart weight/tibia, myocyte CSA, ANP/BNP/SERCA-2 expression. Echocardiography in 24-month-old males after 30 days rGDF11 vs vehicle.
• Specificity test: Pressure-overload hypertrophy via transverse aortic constriction (TAC) in 2-month-old females; daily rGDF11 (0.1 mg/kg) vs vehicle for 30 days; assessed heart weight/tibia, CSA, fibrosis, and echo at days 15 and 30.
• Statistics: Student's t-test (two-tailed, unequal variances) or one-way ANOVA with Bonferroni; p<0.05 significant. Results reported as mean ± s.e.m.

• Heterochronic parabiosis reverses age-related cardiac hypertrophy:
  • Old mice exposed to young circulation (O-HP, 4 weeks) had reduced heart weight/tibia length vs old isochronic controls (O-IP): 7.93 ± 0.19 vs 9.61 ± 0.21 mg/mm (P<0.05). Myocyte cross-sectional area (CSA) decreased: 220.4 ± 21.9 vs 357.8 ± 25.8 µm² (P<0.05). Similar regression observed in males.
  • Replication using only CD45.2 mice: O-HP vs O-IP heart weight/tibia 8.03 ± 0.38 vs 9.07 ± 0.24 mg/mm (P<0.05); CSA 286.3 ± 22.7 vs 366.4 ± 25.4 µm² (P<0.05). Young partners showed no hypertrophy.
• Not explained by hemodynamics or behavior:
  • Baseline BP: Young CD45.2 = 129.9 ± 2.0 mmHg; Young CD45.1 = 104.1 ± 1.9 mmHg; Old = 98.3 ± 1.8 mmHg. During parabiosis, mean arterial pressure did not differ among groups at 10 weeks; O-HP systolic BP increased vs baseline at weeks 7 and 10. Angiotensin II and aldosterone unchanged. Sham parabiosis (no shared circulation) did not reduce hypertrophy (heart weight/tibia and CSA unchanged).
• Molecular remodeling:
  • In O-HP vs O-IP hearts, ANP and BNP transcripts significantly reduced; SERCA-2 increased, indicating anti-hypertrophic and potentially improved diastolic signaling.
• Candidate factor identification:
  • Metabolomics/lipidomics showed no significant differences. Proteomics (SOMAscan) identified 13 age-discriminating analytes; GDF11, a TGFβ family member, declined with age and was restored to youthful plasma levels in O-HP. Tissue analysis showed widespread GDF11 expression with age-related decline particularly in spleen.
• Mechanism and in vitro action:
  • rGDF11 (50 nM) inhibited phenylephrine-induced 3H-leucine incorporation in neonatal rat cardiomyocytes; myostatin at 50 nM did not. In human iPSC-derived cardiomyocytes, both rGDF11 and myostatin increased pSMAD2/3 and suppressed FoxO phosphorylation, consistent with TGFβ pathway activation.
• In vivo rGDF11 therapy reverses hypertrophy in aged mice:
  • Daily rGDF11 (0.1 mg/kg i.p., 30 days) vs saline in 23-month-old females reduced heart weight/tibia (P=0.0008) and myocyte CSA (P=0.0013). Molecular changes mirrored parabiosis: BNP reduced, ANP trended down, SERCA-2 increased. Echocardiography after 30 days showed no significant changes in functional parameters.
• Specificity:
  • rGDF11 did not prevent hypertrophy after pressure overload (TAC): no significant differences in heart weight/tibia (P=0.4), CSA, or fibrosis vs vehicle.

The findings demonstrate that age-related cardiac hypertrophy is reversible through exposure to a young systemic environment, implicating circulating factors rather than hemodynamic or behavioral changes. Proteomic screening identified GDF11 as an age-regulated circulating factor that declines with age and is restored by heterochronic parabiosis. Restoring GDF11 to youthful levels in old mice recapitulated structural and molecular reversal of hypertrophy, and GDF11 exerted direct anti-hypertrophic effects on cardiomyocytes in vitro via TGFβ signaling and modulation of FoxO phosphorylation. The lack of effect in pressure-overload hypertrophy indicates specificity to aging-related mechanisms rather than generalized anti-hypertrophic action. While GDF11 appears central, other age-regulated factors may also contribute. The work suggests a hormonal component to cardiac aging and highlights GDF11 as a potential therapeutic target, though translation to human disease remains to be established.

This study shows that circulating factors from young mice reverse age-related cardiac hypertrophy and identifies GDF11 as a key age-regulated mediator capable of restoring youthful cardiac structure and gene expression in old mice. These results open therapeutic avenues aimed at replenishing GDF11 or modulating its signaling to treat age-related diastolic dysfunction. Future research should: determine causal mechanisms and receptor interactions underlying GDF11’s specificity; assess long-term functional benefits and safety of GDF11 therapy; delineate contributions of other age-regulated circulating proteins; and evaluate relevance, levels, and effects of GDF11 in humans with age-related cardiac hypertrophy.

• Human relevance is unproven; no direct evidence that GDF11 regulates age-related hypertrophy in humans, and human circulating levels are much lower than in mice.
• Other circulating factors likely contribute; the study does not establish GDF11 as the sole mediator of parabiosis-induced reversal.
• Echocardiography after 30 days of rGDF11 showed no significant functional changes despite structural remodeling.
• GDF11 did not attenuate pressure-overload hypertrophy, indicating limited generalizability across hypertrophy etiologies.
• Affinity/promiscuity within TGFβ/activin receptor families complicates interpretation of specificity relative to myostatin and other ligands.