Growth factor release during preparation and storage of platelet concentrates

The platelet content of platelet-derived growth factor (PDGF), a mitogen stored in the alpha-granules, was studied during preparation and storage of platelet concentrates (PC) and compared to the growth-promoting activity of platelets, beta-thromboglobulin (beta-TG) and lactate dehydrogenase (LD). We compared PC prepared from platelet-rich plasma (PRP-PC; n = 10) and from buffy coat. Two different pre-preparation storage periods of the buffy coat were used: 4 h (BC-PC:4h; n = 10) and 24 h (BC-PC:24h; n = 5). The platelet content of PDGF and beta-TG was measured by a RIA technique and the growth-promoting activity by incorporation of 3H-thymidine in stimulated fibroblasts. The platelet content of PDGF, beta-TG and the growth-promoting activity of the platelets decreased in a similar way during preparation and storage of PRP-PC (31 +/- 2, 35 +/- 2 and 33 +/- 7%, respectively, at day 5 of storage; mean +/- SEM). The release of LD was minor (3.9 +/- 0.5% at day 5). At day 1 of storage the platelet content of PDGF was significantly better preserved in BC-PC:4h than in BD-PC:24h (88 +/- 2 and 81 +/- 3%, respectively; p = 0.03). Comparing BC-PC:4h and PRP-PC we found a significantly better preservation of PDGF in BC-PC:4h until day 3 of storage (80 +/- 2 and 75 +/- 1%, respectively at day 3; p = 0.046). In conclusion the preparation of PC according to the PRP method initially induces a higher loss of PDGF, and hence of the growth-promoting activity, than the BC method.