What is the most effective way to get a product into a tendon?

Introduction

Many products exist for the treatment of equine tendinopathy which may be delivered systemically, regionally or intralesionally. Objective analysis of methods of delivery and the persistence of products after delivery would be clinically beneficial.

Search method

Relevant literature was retrieved from the Medline database using the PubMed search engine. The search terms ‘equine tendon treatment’ and ‘intralesional tendon treatment’ were entered. Given the current interest in the use of regenerative therapy and the ability to label these products, the terms ‘tendon stem cell’ and ‘equine stem cell’ were also entered.

Quality and quantity of evidence

Articles were screened based on their abstracts to include those with evidence relating to the delivery of products to tendon lesions and their persistence in the lesion after treatment; evidence evaluating the effects of treatment was discarded. Review articles were included if they evaluated methods of product delivery. Despite the large number of articles initially retrieved only 5 experimental studies were evaluated. All of the studies involved low numbers of animals and variable methodology (method of cell labelling and detection, model of tendinopathy, duration of monitoring) making direct comparison difficult. Becerra et al. [1] evaluated the distribution of labelled autologous mesenchymal stromal cells (MSC) for 24 h after intravenous injection, intralesional injection and intravenous regional limb perfusion (IVRLP) in 13 horses with naturally occurring tendinopathy/ desmopathy in the metacarpal region. Intralesional injection, IVRLP and intra-articular regional limb perfusion (IARLP) was similarly evaluated by Sole et al. [2] in a surgically induced model of superficial digital flexor tendonitis in 6 horses. Migration and persistence of MSC post intralesional implantation has been studied using labelling with nanoparticles [3] and fluorescent proteins [4] in experimentally induced SDFT lesions. Fluorescent proteins were also used by Lacitignola et al. [5] to monitor the fate of MSC in a fibrin scaffold after intralesional injection in an ovine model of collagenase induced tendonitis in a blinded controlled trial. Specific recommendations regarding the methodology of intralesional injection are limited to level V or VI evidence [6]. […]