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#### Introduction

Matrix therapy was introduced as a new branch in regenerative medicine led by the concept that reorganization of the extracellular matrix (ECM) and restoration of the cellular micro-environment can trigger a regeneration process. Robust demonstration were provided in many publications [1] describing the efficacy of ReGeneraTing Agents (RGTA®) in improving speed and quality of healing of various injured tissues (skin, cornea, muscle….) both in preclinical models and in clinic without any report of toxicity. RGTA® are nano- biodegradable polymers engineered to mimic and replace heparan sulfates both as a storage and protector site for growth factors as well as a scaffold element in the reconstruction and organization of the ECM of injured tissues. Horse tendonitis represents a big challenge for trainers and veterinarians and currently, no treatment has clearly proven its effectiveness in improving tendon healing. We now present several studies demonstrating that one dedicated RGTA® named EQUITEND® presents an efficient alternative for the treatment of tendonitis and recovery of horses’ performances.

#### Methods

Three studies were conducted by the CIRALE’s team. EQUITEND® has been tested in tendon healing after a single intra-lesional injection and under ultrasound guidance. The first one is a retrospective study included 16 French trotters with Superficial Digital Flexor Tendinopathy (SDFT) treated once with EQUITEND® and compared with a matching group. The second one is an experimental efficacy study on 12 experimental French Trotters after surgical induced SDFT [2]. The last one is a controlled randomized clinical trial conducted on 22 French Trotters (FT) race horses with spontaneous cases of tendonitis.

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#### Results

The retrospective study demonstrates that horses treated with EQUITEND® went back in racing 2.4 months earlier and earned more in races than control group (74%, versus 15% in the control group). In the experimental efficacy study, improvement was suspected during the follow up of healing by echography but confirmed and quantified by measuring and comparing the mechanical resistance to rupture on isolated tendons at 3 months after injury. Taking into account of the horses’ age in the statistical analysis, (as it is a determining factor in the SDFT incidence), results revealed a significant positive effect of the EQUITEND® treatment on maximal force (p = 0.0038) and on the stress at maximal force (p = 0.058).

Finally, clinical trial has shown that EQUITEND® treated horses went back to racing in a shorter time, their performance as earning per race (compared to earnings per race before injury) was higher and they tend to have fewer tendonitis recurrence than placebo horses.

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#### Discussion

All these studies demonstrated a good tolerance of EQUITEND®, a quick improvement of healing assessed by the ultrasound examination and a better recovery of horse’s performances in EQUITEND® treated group. The experimental study detailed the improvement of quality of healing evaluated by mechanical resistance properties of tendon to rupture, significantly higher for EQUITEND® horses. We conclude that EQUITEND® offers a real advantage upon existing therapies for tendonitis in racing horses.

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#### References

- Johan van Neck, Bastiaan Tuk, Denis Barritault and Miao Tong Heparan Sulfate Proteoglycan Mimetics Promote Tissue Regeneration: An Overview chapter 4 in Tissue Regeneration – From Basic Biology to Clinical Application ISBN 978-953-51- 0387-5, edited by Jamie
- Schramme et al (2010). Vet Comp Orthop 2010;23(4):231-9.