Release of platelet‐derived growth factors and proliferation of fibroblasts in the releasates from platelets stored in the liquid state at 22°C after stimulation with agonists

BACKGROUND: Fresh platelet (PLT)‐rich plasma (PRP) treated with thrombin plus calcium chloride (CaCl 2 ) is used to prepare a PLT gel to promote hemostasis and wound healing in a variety of surgical procedures. The effects of various agonists on stimulating the release of growth factors from liquid‐preserved PLTs and the effects of the PLT releasate on the growth of fibroblasts in tissue culture were investigated. STUDY DESIGN AND METHODS: Plateletpheresis PLTs stored at 22°C as high‐yield PLTs for 3 to 6 days or outdated PLTs for 9 days were treated with agonists to assess release of platelet‐derived growth factor (PDGF) AA, PDGF AB, PDGF BB, transforming growth factor‐β1 (TGF‐β1), and osteocalcin and the proliferation of fibroblasts treated with the PLT releasates in tissue culture. RESULTS: All treatments except for CaCl 2 alone and zeolite‐CaCl 2 produced significant increases in PDGF AA compared to PRP. Thrombin‐CaCl 2 produced significant increases in PDGF BB. Treatment by all the agonists produced similar increases in PDGF AB. TGF‐β1 and osteocalcin levels after treatment were similar to those in PRP. PRP releasate before and after stimulation with different agonists increased proliferation of fibroblasts in tissue culture. CONCLUSION: High‐yield and outdated liquid‐preserved PLTs released PDGF AA, AB, and BB but not TGF‐β1 or osteocalcin. The releasate from untreated PRP stimulated the proliferation of fibroblasts in tissue culture similar to the releasates from PRP treated with the different agonists. Further studies are needed to assess whether or not high‐yield and outdated PLTs may be useful in wound healing.