Numbers of platelets in PRP and PRGF preparations are shown in Fig. 1 (upper panel). Platelets were significantly concentrated both in the PRP and PRGF preparations, and the concentration rate of PRP preparations was substantially higher than that of PRGF preparations (8.79-fold vs. 2.84-fold). Numbers of platelets in A-PRF and CGF preparations calculated by the indirect subtraction method are also shown in Fig. 1 (upper panel). Platelets were significantly concentrated also in both A-PRF and CGF preparations with the concentration rates of 17.85-fold and 15.51-fold, respectively.

Numbers of WBCs in PRP and other PRP derivatives are shown in Fig. 1 (lower panel). WBCs were similarly concentrated in these platelet-concentrated preparations (PRP: 5.51-fold, A-PRF: 11.87-fold, CGF: 8.63-fold). However, only an exception was PRGF preparations; WBCs were almost completely eliminated from PRGF preparations (0.015-fold).

The concentrations of growth factors in PRP, PRGF, A-PRF, and CGF preparations are shown in Fig. 2. The order of growth factor levels (TGF-β1, PDGF-BB, VEGF) were A-PRF ≥ CGF > PRP >> PRGF. PRGF preparations contained the lowest amounts of growth factors.

The concentrations of inflammatory cytokines in PRP, PRGF, A-PRF, and CGF preparations are shown in Fig. 3. IL-1β in PRGF preparations was under detectable levels, while it showed a similar level in other three preparations. For IL-6, in contrast, there were no significant differences among these preparations.

The effects of individual PRP derivatives on the proliferation of human periosteal cells are shown in Fig. 4. As shown in the preceding study [12], PRP preparations exerted a biophasic effect with the maximal effects observed at 2.5 %, while in PRGF preparations, A-PRFext and CGFext stimulated cell proliferation in a dose-dependent manner (0.625–10 %). The apparent order of potency was PRP > CGF > A-PRF > PRGF.