CGRP-expressing stem cells improve osteoarthritis while substance P-expressing cells worsen joint damage | Research

The takeaway

Intra-articular BMSCs expressing αCGRP decreased lateral cartilage damage, improved mobility, and showed bell-shaped inflammation, while SP-expressing BMSCs accelerated OA with earlier osteophytes, increased bone changes, and rising pain markers.

CGRP protects, SP destroys joints
αCGRP-BMSCs reduced cartilage damage and improved mobility while SP-BMSCs accelerated OA with earlier osteophytes—opposite neuropeptide effects on joints

What the researchers found

αCGRP-BMSCs: reduced lateral cartilage OARSI scores, improved mobility, bell-shaped inflammation curve, increased adiponectin. SP-BMSCs: earlier osteophytes (8 weeks), more subchondral bone changes, decreased mobility, rising pain/inflammation markers. Plain BMSCs: general cartilage/bone benefit.

Why it matters

This provides direct evidence that neuropeptides have opposite effects on joints—CGRP is protective while substance P is destructive. This has major implications for both OA treatment (CGRP agonists) and pain management (SP antagonists).

How the study worked

DMM surgical OA in mice. I.a. injection of rBMSCs transduced with lacZ (control), SP, or αCGRP. Assessment at 2, 8, 16 weeks: motion analysis, OARSI scoring, AFM, nano-CT, serum markers.

What this study cannot tell us

Xenogeneic transplant (rat cells in mice). Small group sizes likely. Transduced cells may not replicate physiological peptide release. Medial cartilage (main OA site) showed less treatment response than lateral.

How to read the evidence

Well-designed preclinical study with comprehensive joint assessment. Strong mechanistic evidence for neuropeptide roles in OA.

When this study was published

Published in 2025.

The bigger picture

This study reveals neuropeptides as direct modulators of joint disease, not just pain mediators. CGRP may be anabolic (protective) while SP is catabolic (destructive) in joints, suggesting neuropeptide-targeted OA therapies.

Questions still open

Could CGRP agonists be developed as joint-protective agents?
Should SP antagonists (aprepitant) be tested for OA?
Would combining CGRP agonism with SP antagonism provide synergistic OA benefit?

Common questions

Can neuropeptides treat osteoarthritis?

This study shows CGRP (delivered via stem cells) protected joints from OA damage and improved mobility. In contrast, substance P accelerated joint destruction. This suggests CGRP-based therapies could become new OA treatments, while blocking substance P could prevent joint deterioration.

What is the difference between CGRP and substance P in joints?

Both are nerve peptides found in joints, but they have opposite effects. CGRP appears to be anabolic—protecting cartilage and resolving inflammation. Substance P is catabolic—promoting bone spurs, inflammation, and joint damage. Understanding this difference could lead to targeted OA therapies.

Read the original research

Effects of intra-articular applied rat BMSCs expressing alpha-calcitonin gene-related peptide or substance P on osteoarthritis pathogenesis in a murine surgical osteoarthritis model.

Stem cell research & therapy, 16(1), 117

View on PubMed ↗Publisher’s paper ↗

Citation

Stöckl, Sabine; Taheri, Shahed; Maier, Verena; Asid, Amir; Toelge, Martina; Clausen-Schaumann, Hauke; Schilling, Arndt; Grässel, Susanne. (2025). Effects of intra-articular applied rat BMSCs expressing alpha-calcitonin gene-related peptide or substance P on osteoarthritis pathogenesis in a murine surgical osteoarthritis model.. Stem cell research & therapy, 16(1), 117. https://doi.org/10.1186/s13287-025-04155-2