Scintigraphic tracking of mesenchymal stem cells after intravenous regional limb perfusion and subcutaneous administration in the standing horse.
Authors: Spriet Mathieu, Buerchler Sabine, Trela Jan M, Hembrooke Tara A, Padgett Kerstien A, Rick Mark C, Vidal Martin A, Galuppo Larry D
Journal: Veterinary surgery : VS
Summary
# Mesenchymal Stem Cell Distribution in Standing Horses: Delivery Method Matters Regional limb perfusion (RLP) and subcutaneous injection are both used to deliver mesenchymal stem cells (MSC) to equine tissues, but their effectiveness depends critically on whether the horse is standing or anaesthetised—a distinction with significant practical implications for field-based regenerative medicine. This experimental study used radiolabelled MSC and scintigraphic imaging to track cell distribution, uptake and persistence in 12 standing, sedated horses receiving either RLP (via the cephalic vein or lateral palmar digital vein) or subcutaneous injection to the metacarpal region or coronary band, with imaging at injection, 1, 6 and 24 hours post-administration. RLP in standing horses showed considerably greater variability, lower cellular uptake, reduced persistence and poorer tissue distribution compared with equivalent procedures performed under general anaesthesia in earlier studies—findings attributed to partial or complete tourniquet failure in the conscious animal. Subcutaneous injections resulted in systemic loss of cells without evidence of local retention or migration. These findings underscore that standing RLP delivery protocols require further refinement to optimise tourniquet application and cell retention; clinicians should be aware that current standing procedures may deliver fewer viable cells to target tissues than anesthetised protocols, and should consider this when evaluating efficacy of regenerative treatments in their own populations.
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Practical Takeaways
- •Current standing protocols for RLP-based stem cell delivery are unreliable—general anesthesia achieves significantly better cell retention and distribution at treatment sites
- •Subcutaneous MSC injections alone do not result in local cell migration, suggesting they require additional techniques or adjuvants to remain localized
- •If using stem cell therapy in standing horses, expect variable outcomes with RLP unless tourniquet technology is improved; consider anesthesia for reproducible results
Key Findings
- •RLP in standing horses showed greater variability, lower uptake, and poorer persistence compared to anesthetized horses due to tourniquet failure
- •Subcutaneous MSC injections in metacarpal and coronary band areas resulted in loss to general circulation without local retention
- •Tourniquet integrity was compromised in standing sedated horses, reducing RLP efficacy for stem cell delivery