# NOTUM Enhances Cartilage Repair via Wnt/β-Catenin Modulation in a Rabbit Osteochondral Defect Model

## TL;DR

NOTUM improves cartilage repair in rabbits with joint damage by regulating the Wnt/β-catenin pathway, showing better results than other treatments.

## Contribution

This study demonstrates NOTUM's efficacy in enhancing cartilage repair through Wnt/β-catenin modulation in an osteochondral defect model.

## Key findings

- NOTUM increased cartilage synthesis and reduced degradation compared to hyaluronic acid.
- Histological analysis showed superior tissue repair in NOTUM-treated joints.
- NOTUM modulates Wnt/β-catenin signaling to promote cartilage homeostasis in osteoarthritis.

## Abstract

Osteoarthritis (OA) is the most common multifactorial joint disease characterized by progressive cartilage degradation and impaired tissue repair. Osteochondral defects represent a major clinical challenge within OA, as damage to cartilage and underlying bone can initiate degenerative changes and contribute to joint deterioration. The Wnt/β-catenin signaling pathway plays an important role in OA pathogenesis, and its dysregulation contributes to chondrocyte catabolism and cartilage loss. NOTUM, an extracellular Wnt inhibitor, has emerged as a potential therapeutic modulator capable of restoring signaling balance and promoting cartilage homeostasis. This study aimed to evaluate the efficacy of NOTUM compared with hyaluronic acid (HA), human adipose-derived mesenchymal stromal cells (hAd-MSCs), and Colchicine in a rabbit osteochondral defect model relevant to osteoarthritis. Twenty-seven New Zealand White rabbits underwent standardized femoral condyle injury and received single-dose treatments. Serum levels of cartilage biomarkers—Procollagen Type IIA N-terminal Propeptide (PIIANP) and Cartilage Oligomeric Matrix Protein (COMP)—were measured by ELISA at 4, 6, and 8 weeks post-surgery, and histological repair at week 12 was assessed using the modified O’Driscoll scoring system. NOTUM treatment significantly increased PIIANP and decreased COMP levels compared with HA, indicating enhanced cartilage synthesis and reduced degradation. Histological scores confirmed superior surface morphology and tissue composition in NOTUM-treated joints. These findings suggest that NOTUM performs a protective and regenerative effect through Wnt/β-catenin modulation, supporting the conclusion that it enhances osteochondral defect repair and motivating further studies of NOTUM as an OA therapy.