Growth factor concentration in canine platelet-rich plasma and platelet lysate is correlated with platelet number

Platelet lysate (PL) and platelet-rich plasma (PRP) are blood derivatives that have gained increasing clinical relevance in both human and veterinary medicine in recent years. These derivatives exhibit anti-inflammatory and regenerative potential due to the presence of multiple growth factors (GFs) and cytokines stored in platelet cytoplasmic granules, which can be disrupted and harvested. Currently, there are no standardized protocols or specific consensus for the preparation and production of canine PRP and PL. This study aims to compare and correlate platelet concentration in various platelet concentrates (PCs) obtained through an in-house method, with the presence of three different GFs: vascular endothelial growth factor A (VEGF-A), transforming growth factor beta-1 (TGF-β1), and platelet-derived growth factor BB (PDGF-BB). Eight healthy adult dogs that met pre-established inclusion criteria were enrolled in the study, with assessments conducted at two time points, separated by a 4-month interval. Research was conducted in accordance with experimental ethics protocols established by the University. Blood samples were collected into EDTA and sodium citrate tubes in order to obtain whole blood samples as well as various plasma derivatives: plasma, leukocyte-reduced PRP, platelet-poor plasma, and PL. The presence and concentration of GFs were analyzed using canine-specific ELISA kits. Results show that TGF-β1 and PDGF-BB concentrations were significantly higher in PRP and PL samples. Furthermore, GF concentrations were higher in PL samples compared to PRP, suggesting that the in-house method employed may be able to increase both platelet and growth factor concentrations. In addition, a strong positive correlation (r² = 0.7195) was established between platelet concentration and TGF-β1 growth factor levels. The findings of this study suggest that the in-house method used is able to concentrate platelets and growth factors such as TGF-β1 and PDGF-BB in platelet-concentrated products like PRP and PL. In conclusion, platelet concentration may serve as a predictive parameter for estimating specific GF concentrations such as TGF-β1. Due to the fact that platelet counts are easily and rapidly obtainable, this parameter could direct the selection of GF-rich plasma samples to be used in interventions requiring enhanced bone regeneration and may also help to estimate the quantity of GFs delivered during the treatment.