The purpose of this study was two-fold: to evaluate whether the timing of collection influences the platelet counts and leukocyte counts of PRP samples, and to evaluate growth factor concentrations in canine PRP after freezing and storage without a preservation agent for 6 months of time. We hypothesized that the platelet count would not change with time of collection and preparation. Furthermore, the growth factor concentrations of the PRP samples would be measurable and consistent with prior literature after freezing at -20℃ and subsequent thawing of the samples. Whole blood collection was performed three times over the course of four weeks. All PRP samples were evaluated with a CBC analysis. The PRP samples were frozen and stored without a preservation agent for the duration of the 4-week study. The platelet and leukocyte counts were not statistically significant between the timing of blood draws over the course of 4 weeks. All three growth factors were present in measurable quantities after freezing and storage for 6 months without a preservation agent. PDGF, TGF-β1, and VEGF were all present in measurable quantities. Study limitations include small sample size and lack of baseline growth factor concentration measurements. Furthermore, PDGF and TGF-β1 were correlated with platelet count of the final PRP. VEGF concentrations were able to be quantified. We correctly hypothesized growth factor concentrations would be present and measurable in canine PRP frozen and stored without a preservation agent for 6 months.
