Interleukin-1β in tendon injury enhances reparative gene and protein expression in mesenchymal stem cells.
Authors: Koch Drew W, Berglund Alix K, Messenger Kristen M, Gilbertie Jessica M, Ellis Ilene M, Schnabel Lauren V
Journal: Frontiers in veterinary science
Summary
Equine tendon injuries carry substantial clinical and economic consequences, with reinjury rates around 50–65% despite optimal management; whilst intralesional mesenchymal stem cell (MSC) therapy has shown promise in improving tissue architecture, the mechanisms underlying its reparative effects remain incompletely understood, particularly regarding how inflammatory priming of MSCs might enhance their therapeutic potential. Koch and colleagues used microdialysis probes to characterise the temporal cytokine profile in surgically induced equine tendon injuries, then exposed MSCs in vitro to the predominant inflammatory mediators identified in vivo—specifically interleukin-1β (IL-1β) and IL-6—at physiologically relevant concentrations to assess changes in gene and protein expression. Only IL-1β induced substantial upregulation of genes critical to tendon healing, including those governing vascular development, extracellular matrix synthesis and remodelling, growth factor signalling, and immunomodulation, with protein analysis confirming significantly elevated IL-6, vascular endothelial growth factor (VEGF), and prostaglandin E2 (PGE2) in IL-1β-primed MSCs compared to naïve cells. These findings suggest that timing MSC administration to coincide with the peak inflammatory window (within 48 hours post-injury) or pre-treating MSCs with IL-1β ex vivo before implantation could substantially amplify their reparative capacity, offering a mechanism to improve healing outcomes and reduce reinjury risk in this notoriously problematic condition.
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Practical Takeaways
- •Consider administering MSC therapy within 48 hours of tendon injury when the inflammatory cytokine milieu naturally enhances their reparative capacity
- •Pre-licensing MSCs with IL-1β in vitro before injection may enhance their therapeutic effect and could reduce reinjury rates currently estimated at 50-65%
- •The inflammatory phase is not merely destructive—exploiting it therapeutically by timing or pre-conditioning MSCs may improve healing outcomes
Key Findings
- •IL-1β and IL-6 peak within 48 hours post-tendon injury in vivo, with IL-1β being the dominant pro-inflammatory cytokine driving reparative responses
- •IL-1β exposure licenses MSCs to upregulate genes involved in vascular development, ECM synthesis/remodeling, and immunomodulation
- •IL-1β-licensed MSCs show significantly increased protein expression of IL-6, VEGF, and PGE2 compared to naive MSCs
- •Optimal timing for MSC administration may be within the first 48 hours post-injury to leverage the inflamed microenvironment, or MSCs can be pre-licensed with IL-1β in vitro before application