Growth factor levels in leukocyte-poor platelet-rich plasma and correlations with donor age, gender, and platelets in the Japanese population.

BACKGROUND: Clinical application of platelet-rich-plasma (PRP) has been accelerated to investigate early recovery from various musculoskeletal conditions. It involves the promotion of tissue damage repair through the action of multiple growth factors at physiological concentrations. The composition of PRP differs based on many factors, which may include age and gender. Therefore, we analyzed correlations between age, gender, and platelet counts in PRP with growth factors in Japanese subjects. METHOD: Peripheral blood was drawn from 39 healthy volunteers between 20 and 49 years of age (age, mean ± standard deviation = 33 ± 8.7 years; gender ratio, male:female = 19:20; BMI, mean ± standard deviation = 22 ± 4.0) and prepared through centrifugation (volume, 6 mL per sample). After being activated with CaCl(2), the supernatant was stored. The mean platelet count in PRP was 41.4 ± 12.2 × 10(4)/μL. PRP concentration rate (i.e., PRP/peripheral platelet counts) was 1.8 ± 0.4 times. Growth factor levels (platelet-derived growth factor-BB, transforming growth factor-β1, vascular endothelial growth factor, epidermal growth factor, fibroblast growth factor, insulin-like growth factor-1, and hepatocyte growth factor) were measured using enzyme-linked immunosorbent assay (ELISA), and correlations with age, gender, and PRP platelet counts were statistically analyzed by calculating Spearman's rank correlation coefficients (r). RESULTS: Age was negatively correlated with platelet-derived growth factor-BB and insulin-like growth factor-1 (r = - 0.32, - 0.39), and gender had no influence on growth factors. Platelet counts in PRP positively correlated with platelet-derived growth factor-BB, transforming growth factor-β1, epidermal growth factor, and hepatocyte growth factor (r = 0.39, 0.75, 0.71, and 0.48, respectively). CONCLUSIONS: This clinical study shows a significant variation of PRP among individual patients and that this variation is influenced by the age and the platelet counts of the subjects. Our data demonstrate that patient characteristics account for the differences in PRP physiological activity.