Background: It is unclear whether platelet-rich plasma is a
clinically effective adjunct to osteoinductive agents such as demineralized
bone matrix. It contains platelet-derived growth factor (PDGF), which
decreases osteoinduction by human demineralized bone matrix in nude-mouse
muscle, suggesting that platelet-rich plasma may also have a negative impact.
This study tested the hypothesis that platelet-rich plasma reduces
demineralized bone matrix-induced bone formation and that this effect varies
with donor-dependent differences in platelet-rich plasma and demineralized
Methods: Human platelet-rich plasma was prepared from blood from six
men (average age [and standard error of the mean], 29.2 ± 2.4 years).
Platelet numbers were determined, and growth factors were quantified before
and after platelet activation. Human demineralized bone matrix from two donors
(demineralized bone matrix-1 and demineralized bone matrix-2) was mixed with
activated platelet-rich plasma and was implanted bilaterally in the
gastrocnemius muscle in eighty male nude mice (eight implants per variable).
Fifty-six days after implantation, the hindlimb calf muscles were harvested
for histological analysis. Osteoinduction was evaluated with use of a
qualitative score and morphometric measurements of ossicle size, new bone
formation, and residual demineralized bone matrix.
Results: Compared with platelet-poor plasma, platelet-rich plasma
preparations exhibited a fourfold increase in the platelet count, a
fifteenfold increase in the amount of transforming growth factor-ß, a
sixfold increase in the amount of PDGF-BB, a fivefold increase in the amount
of PDGF-AA, and a twofold increase in the amount of PDGF-AB. Demineralized
bone matrix-1 was more osteoinductive than demineralized bone matrix-2, as
determined on the basis of a greater ossicle area. The effect of platelet-rich
plasma was either neutral or inhibitory depending on the demineralized bone
matrix batch. When used with demineralized bone matrix-1, platelet-rich plasma
did not alter the qualitative score or overall ossicle size, but it decreased
the new bone area. When used with demineralized bone matrix-2, platelet-rich
plasma reduced the qualitative score, ossicle area, and new bone area and
increased the amount of residual demineralized bone matrix. The effects on
osteoinduction also varied with the donor of the platelet-rich plasma.
Conclusions: Platelet-rich plasma decreased the osteoinductivity of
demineralized bone matrix implanted in immunocom-promised mice, and the
activities of both demineralized bone matrix and platelet-rich plasma were
Clinical Relevance: Platelet-rich plasma may not be an appropriate
adjunct to demineralized bone matrix in some clinical applications.