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Stanford Study Identifies Enzyme Inhibitor for Potential Muscle and Cartilage Regeneration

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From Lab to Clinic: A New Drug Target for Muscle and Cartilage Repair

A series of studies led by researchers at Stanford Medicine has identified that inhibiting the enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) may promote muscle regeneration and cartilage regrowth in mice. A drug compound targeting this enzyme, MF-300, has completed Phase 1 safety trials in humans, with further trials planned.

Muscle Regeneration and GLP-1 Medications

Key Findings

A study published on June 2 in the Proceedings of the National Academy of Sciences found that a 15-PGDH inhibitor (PGDHi) reduced muscle loss associated with GLP-1 weight loss drugs in young adult mice.

  • Methodology: Obese male mice fed a high-fat diet for 12 weeks were treated with semaglutide, a PGDHi, or both for five weeks.
  • Results: Mice receiving semaglutide alone lost approximately 25% of their body weight, including significant fat and skeletal muscle mass. While muscle strength under normal conditions remained unaffected, the regenerative capacity of muscles after injury was impaired.
  • Combination Treatment: Mice receiving both semaglutide and PGDHi showed restored regenerating muscle fiber size and improved strength recovery after injury, compared to those on semaglutide alone. The addition of PGDHi did not reduce fat loss.
  • PGDHi Alone: In young healthy mice without injury, PGDHi alone had no effect on muscle strength.

Background

The enzyme 15-PGDH limits the availability of prostaglandin E2, a molecule essential for activating muscle stem cells. Previous research (2021) by Dr. Helen Blau's lab found that 15-PGDH levels increase after injury and become more prevalent with age, potentially impairing muscle repair. Muscle loss associated with GLP-1 drugs is not unique to those medications, as similar effects occur with caloric restriction in general.

"There is a major unmet need for a drug that can help GLP-1 users preserve their muscle health and strength."
— Helen Blau, PhD, senior author

"It wasn't just that there was an initial loss of muscle with the GLP-1 receptor agonist - it also reduced the regenerative capacity of the young mouse muscles."
— Minas Nalbandian, PhD, first author

Cartilage Regeneration

Key Findings

A separate study led by Stanford researchers identified that blocking the 15-PGDH protein reversed cartilage loss in older mice and prevented osteoarthritis development in injured mice.

  • Aging and 15-PGDH: Comparison of knee cartilage from young and old mice revealed that 15-PGDH levels doubled with age. Researchers refer to 15-PGDH as a "gerozyme" due to its increased levels with age and its contribution to loss of tissue function.
  • Older Mice: Older mice injected with a 15-PGDH inhibitor, either systemically or directly into the knee joint, exhibited thickened hyaline cartilage across the joint surface. Analysis of chondrocytes (cartilage-producing cells) showed a shift in gene expression toward a more youthful, functional state.
  • Injury Model: Mice with ACL-like knee injuries that received twice-weekly injections of the inhibitor for four weeks post-injury were significantly less likely to develop osteoarthritis compared to control groups. Treated mice also showed improved mobility and weight-bearing on the injured leg.
  • Mechanism: The effect did not involve stem cells. Instead, existing chondrocytes altered their gene expression patterns to a healthier, more functional state.

Human Cartilage Samples

Human cartilage samples from osteoarthritis patients undergoing total knee replacement surgery responded to the 15-PGDH inhibitor after one week. The tissue showed reduced numbers of 15-PGDH-producing chondrocytes, decreased expression of degradation markers, and early signs of articular cartilage regeneration.

"It's clear that a large pool of already existing cells in cartilage are changing their gene expression patterns."
— Nidhi Bhutani, associate professor of orthopaedic surgery

Osteoarthritis Context

Osteoarthritis is a degenerative joint disease affecting approximately one in five U.S. adults, with direct healthcare costs estimated at $65 billion annually. Current treatments address pain or involve surgical joint replacement; no approved drugs slow or reverse cartilage damage.

Clinical Implications and Future Steps

Drug Development

  • The PGDHi compound MF-300 has completed Phase 1 safety trials in humans, demonstrating safety and activity in healthy volunteers.
  • Phase 2b trials for age-related muscle loss (sarcopenia) are planned for later this year.
  • Researchers have expressed hope that a similar trial for cartilage regeneration may proceed. The Colorado Boulder team developing a separate slow-release drug-delivery system for cartilage repair has stated they aim to begin clinical trials within 18 months.

"This is a new way of regenerating adult tissue, and it has significant clinical promise for treating arthritis due to aging or injury."
— Helen Blau, PhD

Limitations

The drugs have not yet been tested in older obese individuals, who may have different risk factors for muscle loss or cartilage degeneration.

Funding and Disclosures

The research was supported by the Baxter Foundation, Milky Way Research Foundation, Stanford Cardiovascular Institute, Stanford Bio-X, National Institutes of Health (grants R01AG02096115, R01AG069858-01, R01DK125260, P30DK116074, RHG009674A), American Heart Association, Arc Institute, and NIH Pathway to Independence Award (K99AR081618).

Blau, Bhutani, and co-authors have patent applications related to 15-PGDH inhibition in cartilage and tissue rejuvenation, licensed to Epirium Bio. Blau is a co-founder of Myoforte/Epirium and holds equity in the company.