PTOtherJournal of physical therapy science2025

Effect of hypoxia-inducible factor 1 alpha inhibitor on immobilization-induced muscle fibrosis related to muscle contracture.

Yasuhiro Kajiwara, Yuichiro Honda, Ayumi Takahashi and 6 others

PMID 40599839

WHAT IT FOUND

In rats with casted ankles, an experimental drug called YC-1 reduced muscle stiffening and collagen buildup compared to untreated immobilized rats.

The drug improved ankle flexibility at 3 and 4 weeks. This is animal data only; it does not show the drug works or is safe in humans.

Key findings

01The YC-1 group had significantly higher ankle dorsiflexion range of motion than the untreated immobilization group at 3 weeks.

02YC-1 treatment significantly reduced hydroxyproline content (a marker of collagen/fibrosis) and type I and III collagen mRNA expression compared to the untreated immobilization group.

03YC-1 treatment significantly reduced HIF-1α protein expression and TGF-β1 mRNA expression compared to the untreated immobilization group.

STILL TO COME

How it was doneWhat they found

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What it does not show

This is an animal study using rats, not humans. Results cannot be directly applied to clinical practice. The cast was removed weekly for measurement, so immobilization was not continuous, which may affect how well the model mimics human contracture. Histological analysis of the muscle tissue was not performed, so the structural changes in the muscle were not directly observed. Only one dose of YC-1 was tested, and it was not compared to other potential inhibitors. The study did not examine whether the drug affects the skin or joint capsule, which are also involved in contracture.

Declared interests

Funded by the Japan Society for the Promotion of Science. The funder had no role in the study design, data collection, analysis, publication decisions, or manuscript preparation. The authors declared no conflicts of interest.

The easy way to misread this

Do not interpret these results as evidence that YC-1 or any HIF-1α inhibitor is safe or effective for preventing muscle contracture in patients. This study was conducted in rats with a specific immobilization model, and no human trials are reported here.

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