Ovarian stiffness increases with age in the mammalian ovary and depends on collagen and hyaluronan matrices
TL;DR
Amargant et al. showed that ovaries from reproductively old mice were mechanically stiffer than young ovaries. Ex-vivo collagen depletion reduced old-ovary collagen and stiffness to values statistically indistinguishable from young controls, while age-associated loss of stromal hyaluronan and a catalytically inactive Has3 allele supported a second matrix contribution. In human ovarian cortex, hyaluronan declined across age groups, whereas collagen was higher in the ≥51-year cohort than in the 11–20-year cohort but was also high before puberty; the collagen pattern was not a simple monotonic age increase. This paper established the ovarian-mechanics phenotype that Wu et al. later connected to il-11-signaling.
Design
- Reproductively young (6–12-week) and old (14–17-month) CB6F1 mouse ovaries were assessed by instrumental indentation, histology and matrix assays. The principal age comparison used eight ovaries/cohort, with at least 15 surface measurements/ovary.
- A 1-h ex-vivo type-IV-collagenase treatment compared young control ovaries (n=2), old control ovaries (n=4) and treated old ovaries (n=4). Hyaluronan (HA) histology used n=5 mice/age, stromal Has/Hyal expression used 30 young and 29 old stromal samples, and whole-ovary HA size distributions used n=5 ovaries/age.
- Five-month-old C57BL/6J mice carrying a catalytically inactive Has3 allele were compared with age-matched wild type (n=5/group for stiffness; contralateral ovaries n=3/group for HA/collagen histology).
- Human ovarian cortex came from 60 participants in four age cohorts (0–10, 11–20, 39–50 and ≥51 years). Two 1-mm cores/person yielded 120 tissue-microarray samples; participants with ovarian pathology, prior chemotherapy/radiation and several fibrosis-related confounders were excluded.
Key findings
Old ovaries required 2.5-fold more force to indent and had a higher Young’s modulus than young ovaries (4.56±2.03 versus 1.79±0.08 kPa, mean±SEM, P<0.05). In the collagenase experiment, old controls measured 4.36±1.24 kPa versus 1.98±0.42 kPa in young controls; treated old ovaries measured 2.28±0.61 kPa and were not significantly different from young controls. The treatment preserved gross architecture and measured HA staining, but it was an ex-vivo enzymatic perturbation.
Stromal and theca-associated HA staining fell with age, alongside higher Hyal1 and lower Has3 expression (P<0.05), without a detected age shift in whole-ovary HA molecular-mass distribution. Ovaries with catalytically inactive HAS3 were 2.7-fold stiffer than wild type (6.67±2.00 versus 2.51±0.66 kPa, P<0.05). HA loss and collagen gain in the small contralateral-ovary histology subset were trends, not significant differences.
In the human tissue microarray, HA fluorescence declined with age. Collagen was significantly higher at ≥51 years than at 11–20 years, but the 0–10-year cohort had collagen comparable to the oldest group, which the authors attributed to the fibroblast-rich prepubertal ovary. Vessel-rich cores showed a significant collagen increase and HA decrease with age; stroma-rich cores showed a nonsignificant positive collagen trend and significant HA reduction. Thus, the human result supports age-associated matrix remodeling but not a monotonic collagen trajectory or a direct human stiffness measurement.
Extrapolation to humans
| Dimension | Status | Notes |
|---|---|---|
| Pathway conserved in humans? | partial | Collagen and HA remodeling were measured in human ovarian cortex, but collagenase and Has3 perturbations were mouse-only. |
| Phenotype conserved in humans? | partial | Human matrix composition changed with age; this paper did not measure human ovarian mechanics. |
| Replicated in humans? | no | No human intervention tested whether changing collagen or HA reduces ovarian stiffness or improves reproductive function. gap/needs-human-replication |
Interpretation and limits
The study establishes age-associated matrix remodeling and experimentally links collagen and HA to mouse ovarian mechanics. It did not test fertility rescue after softening, identify IL-11, or establish longitudinal human causality. Collagenase treatment is an ex-vivo perturbation rather than a clinically viable intervention, and mouse whole-ovary indentation does not reproduce the cortex-dominant architecture of the human ovary. HA was detected indirectly with hyaluronan-binding protein, so age-related changes in HA-binding proteins could influence the signal; whole-ovary size profiling could also miss compartment-specific HA fragmentation. Mouse indentation cohorts and the Has3 histology subset were small, and only two mouse age ranges were examined.
Relevance to the requested paper
wu-2026-il11-ovarian-stiffness extends this mechanical framework with human cortical AFM, fibroblast perturbations and rodent genetic/RNA interventions targeting the TGF-β–IL-11–ERK axis.
Cited by wiki pages
[Auto-populated by Obsidian backlinks panel]