Stimulus-dependent release of tissue-regenerating factors by equine platelets.
Authors: Dunkel B, Bolt D M, Smith R K, Cunningham F M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Stimulus-dependent release of tissue-regenerating factors by equine platelets Platelet-rich plasma has gained considerable traction for treating equine orthopaedic injuries, yet the mechanisms governing release of beneficial growth factors versus potentially harmful inflammatory mediators remained poorly characterised. Dunkel and colleagues investigated which activation stimuli—thrombin, chitosan, or recombinant tumour necrosis factor—could preferentially trigger release of platelet-derived growth factor-BB and transformative growth factor-β whilst minimising release of the pro-inflammatory chemokine CCL5, using washed platelets from six ponies measured over 96 hours. Regardless of stimulus type, growth factor release peaked within 30 minutes to one hour specifically during coagulation, with negligible output thereafter, whereas CCL5 release operated independently of clot formation and persisted significantly longer, particularly with TNF stimulation. These findings suggest that coagulation itself—not the initiating trigger—drives the regenerative response, and that separating platelet supernatants from coagulated samples may offer a more refined therapeutic approach than standard PRP by delivering growth factors without sustained inflammatory signalling. For practitioners, this implies careful consideration of whether activated PRP or platelet lysates represent superior treatment protocols, with implications for injection timing and potential clinical outcomes in soft tissue and cartilage repair.
Read the full abstract on PubMed
Practical Takeaways
- •Coagulated platelet supernatant may be a simpler and potentially more effective alternative to PRP for treating orthopaedic injuries, without the need for stimulus selection
- •To optimize tissue regeneration while minimizing inflammation, avoid high TNF stimulation protocols and use coagulated platelet preparations harvested within the first 1-2 hours
- •The concurrent release of proinflammatory mediators with growth factors suggests PRP treatment protocols should be refined to balance regenerative and inflammatory responses
Key Findings
- •PDGF and TGF-β release from equine platelets is maximal within 0.5-1 hour during coagulation, regardless of stimulus type (thrombin, chitosan, or erTNF)
- •Growth factor release is minimal in noncoagulated samples, indicating coagulation is the key trigger for regenerative factor release
- •CCL5 (proinflammatory mediator) release is independent of coagulation and persists for extended periods beyond 24 hours
- •High concentrations of erTNF induced significantly greater CCL5 release at 6 hours compared to other stimuli tested