Distribution and persistence of technetium-99 hexamethyl propylene amine oxime-labelled bone marrow-derived mesenchymal stem cells in experimentally induced tendon lesions after intratendinous injection and regional perfusion of the equine distal limb.
Authors: Sole A, Spriet M, Padgett K A, Vaughan B, Galuppo L D, Borjesson D L, Wisner E R, Vidal M A
Journal: Equine veterinary journal
Summary
# Editorial Summary: MSC Delivery Routes for Equine Tendon Repair Researchers compared three methods of delivering radiolabelled mesenchymal stem cells (MSCs) to experimentally induced superficial digital flexor tendon lesions in eight horses: direct intralesional injection, intravenous regional limb perfusion (RLP), and intra-arterial RLP, tracking cell distribution and persistence over 24 hours using scintigraphy. Whilst intralesional injection achieved superior initial uptake at the lesion site, all three techniques demonstrated similar rates of MSC clearance over time, and intra-arterial RLP proved more effective than intravenous delivery for distributing cells to target tissues, with notably greater lesion accumulation when performed 10 days post-injury compared to day 3. However, the arterial perfusion technique induced thrombosis in every treated limb and caused clinical complications in one horse, rendering this approach unsuitable for clinical application despite its theoretical advantages. These findings suggest that although regional perfusion cannot match the direct delivery efficacy of intralesional injection, the timing of treatment may influence MSC recruitment to maturing lesions—a consideration relevant to practitioners planning stem cell therapy protocols, though the safety concerns with arterial techniques necessitate continued refinement before clinical adoption.
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Practical Takeaways
- •Intralesional injection remains superior to regional limb perfusion for delivering stem cells directly to tendon lesions, with higher uptake at the injury site
- •Regional limb perfusion techniques should not currently be used clinically due to significant thrombosis risk (50-100%), particularly the intra-arterial approach which caused clinical complications
- •If regional perfusion were to be reconsidered, waiting until Day 10 post-injury appears to improve MSC accumulation at lesion sites compared to early intervention
Key Findings
- •Intralesional injection resulted in higher lesion uptake of MSCs compared to regional limb perfusion techniques
- •MSC persistence decreased similarly over time across all three injection techniques over 24 hours
- •Intra-arterial regional limb perfusion showed better MSC distribution and higher lesion uptake than intravenous regional limb perfusion
- •Time-dependent accumulation of MSCs occurred with intra-arterial perfusion, with greater accumulation on Day 10 versus Day 3 post-lesion
- •Arterial thrombosis occurred in 50% of intravenous and 100% of intra-arterial regional limb perfusion limbs, causing clinical complications