BACKGROUND: The biological effects of platelet-rich plasma gel are affected by many factors, such as the preparation method of platelet-rich plasma, blood platelet integrity, the choice of anticoagulants and activators and so on.
OBJECTIVE: To compare the effects on the release of growth factors from platelet-rich plasma gel with different combinations of anticoagulants and activators. 
METHODS: The whole blood was extracted from New Zealand rabbits to prepare the platelet-rich plasma. The platelet-rich plasma was activated with bovine thrombin and type I collagen in different groups. There were five groups in this experiment: ethylene diamine tetraacetic acid (EDTA)-thrombin group, EDTA-typeⅠcollagen group, heparin-thrombin group, heparin-typeⅠ collagen group, as well as a blank control group (the whole blood). The platelets were counted before and after centrifugation; Transforming growth factor β1 (TGF-β1) and platelet-derived growth factor AB (PDGF-AB) were measured in the platelet-rich plasma gel of all the five groups using the enzyme linked immunosorbent assay at 2 hours, 1, 3, 5 days after the platelet-rich plasma was activated, and release modes of these two growth factors were compared at the same time. 
RESULTS AND CONCLUSION: The cumulative release of TGF-β1 and PDGF-AB was maximal in the EDTA-type Ⅰ collagen group, and significant differences were noted between the EDTA-type Ⅰ collagen group and the other groups (P < 0.05). The use of type I collagen as an activator resulted in sustained release of TGF-β1 and PDGF-AB, and the release of TGF-β1 was in a time-dependent manner (r=0.873); while the aliquots of platelet-rich plasma clotted with thrombin had an immediate release of TGF-β1 and PDGF-AB (P > 0.05). The concentration and methods of the release of growth factors in the EDTA-type Ⅰ collagen group is more conducive to the seed cells of tissue engineering nucleus pulposus differentiated into nucleus pulposus-like cells.