Dickkopf-1 is present in equine platelet-rich plasma and correlates to platelet concentration.

Abstract

Objective: To determine if equine platelet-rich plasma (PRP) contains Dickkopf-1 (Dkk-1) and, if so, to quantify the amount of Dkk-1 in bovine thrombin (BT)-activated PRP and a control platelet lysate created using a freeze-thaw (FT) method.

Methods: 10 adult horses were used in this experimental study. Blood was collected and processed in November 2019 and stored at -80 °C until the ELISAs were performed in October of 2023. Blood was collected from each horse, and PRP was created using a commercially available kit. Known concentrations of platelets were activated using BT or by an FT cycle to create platelet lysates. Dickkopf-1 and platelet-derived growth factor concentrations were measured using ELISAs. Statistics included the Shapiro-Wilks test, Student t tests, linear regression, and Pearson or Spearman correlations (significant at P ≤ .05).

Results: Bovine thrombin created a greater release of Dkk-1 from platelets (250.22 ± 129.09 pg/mL from the combined clot and releasate) than the FT cycle (152.81 ± 62.74 pg/mL). There was a positive correlation between platelet concentration and Dkk-1 for both the FT (r = 0.69) and the BT activation method (r = 0.62). Platelet-derived growth factor was released in FT- and BT-activated PRP (FT = 530.35 ± 253.96 pg/mL; BT = 1391.05 ± 661.50 pg/mL).

Conclusions: Dickkopf-1 is present in equine PRP and is correlated with platelet concentration. Although more investigation of the active proteins in PRP is needed, this study provides the first evidence that equine platelets contain Dkk-1.

Clinical relevance: Equine PRP contains Dkk-1, which could contribute to PRP's mechanism of action.