Klotho-Derived Peptide Preserves Erectile Function by Limiting Fibrosis, Oxidative Stress, and Apoptosis of Penile Smooth Muscle Cells in Cavernous Nerve Injured-Rats Through Suppression of the TGF-β1/TGF-β Type II Receptor Signaling

A Klotho-derived peptide reduced penile fibrosis and preserved erectile function in rats after cavernous nerve injury — no human data yet

Journal: European Journal of Pharmacology | Published: 2026-04-08 | Type: Animal Study | PMID: 41962889 Authors: Xi Yuhang, Han Guangye, Li Xiaojie, Zhang Xinjun, Zhang Shaohua, Ma Kuo, Zhu Feng (Department of Urology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China) Funding/COI: Funding not disclosed. Authors declare no competing financial interests.

Summary

Cavernous nerve injury during radical prostatectomy commonly causes neurogenic ED through corporal fibrosis and smooth muscle cell loss. This rat study tested whether a peptide fragment derived from Klotho — an anti-aging protein already known for anti-fibrotic properties — could block that damage. Rats given bilateral cavernous nerve crush injuries and treated with intrapenile KP injection showed reduced fibrosis, preserved smooth muscle, and improved erectile function at three weeks compared to untreated CNI controls.

Claims

• Bilateral cavernous nerve injury in rats produced severe ED with measurable declines in intracavernous pressure
• KP treatment ameliorated erectile function and partially restored smooth muscle abundance and nitric oxide synthase expression in penile tissue
• KP reduced markers of oxidative stress, apoptosis, and TGF-β1 pathway activation in penile tissue of CNI rats
• In vitro: KP downregulated TGF-β type II receptor in corpus cavernosum smooth muscle cells (CCSMCs) stimulated with TGF-β1, suppressing downstream Smad2/JNK signaling and reactivating PI3K/AKT
• No quantitative effect sizes, intracavernous pressure measurements, or sample sizes per group are reported in the abstract

Study Quality

This is a three-arm rat model study (sham, CNI + saline, CNI + KP) with a three-week endpoint and paired in vitro work using TGF-β1-stimulated CCSMCs. The mechanistic pathway story is internally consistent — TGF-β1 drives fibrosis and apoptosis, KP blocks the receptor, downstream signals shift favorably — and the dual in vivo/in vitro design is a reasonable approach for mechanism hypothesis generation.

The paper provides no group sizes, no intracavernous pressure values, and no effect sizes in the abstract. The three-week endpoint is short, the injury model (bilateral nerve crush) is more severe than most clinical scenarios, and KP was delivered by direct injection rather than any clinically translatable route. The funding source is undisclosed, which is a gap at a time when many peptide studies have pharmaceutical backing.

Red Flags

• No group sizes reported — impossible to assess statistical power from the abstract
• No quantitative results disclosed in the abstract (no ICP values, no fiber ratios, no enzyme activity numbers)
• Funding not listed — unusual for a mechanistic pharmacology paper; raises unanswered questions about who sponsored this work
• Bilateral nerve crush is a maximum-damage model; unilateral or partial injury better approximates most RP cases
• Direct injection delivery is not a practical clinical route; no pharmacokinetic data reported
• Three weeks is a short follow-up for fibrosis and remodeling outcomes
• Single institution, relatively low-profile journal for a novel peptide claim
• No comparison arm against established neuroprotective agents (e.g., PDE5 inhibitors, stem cell approaches) that are already in this preclinical literature

Strengths

• Addresses a real and poorly managed clinical problem: neurogenic ED post-radical prostatectomy affects roughly 50–80% of men undergoing nerve-sparing surgery
• Both in vivo and in vitro arms provide mechanistic plausibility, not just endpoint data
• TGF-β1/Smad2 pathway is well-validated in corporal fibrosis biology — this isn't chasing a novel ghost
• Authors declare no conflicts of interest

Verdict

A mechanistically plausible rat study suggesting Klotho-derived peptide may reduce post-nerve-injury penile fibrosis, with a coherent molecular story behind it. But the abstract withholds the numbers that would let you evaluate whether the effect is large or trivial, the funding is undisclosed, and the distance from rat penis to human clinical application is vast. File this under "hypothesis-generating rodent data" — worth watching if the same group or others replicate it with proper reporting, but not yet actionable science.