Introduction: There is controversy regarding the effectiveness of PRC for bone healing. A possible explanation is the different bone graft substitutes (BGSs) used with PRC. Here we investigated the effect of combining different BGSs with PRC on hBMSCs differentiation and growth factor release from the BGS/PRC composites.

Method: hBMSCs, DBM and allograft were prepared from femoral heads donated by patients undergoing total hip replacement. Growth factor release (TGF-â, VEGF, PDGF-AB, BMP-2) was measured by ELISA. The effect of PRC on hBMSC differentiation was determined by ALP activity and mineralisation. PRC was produced using the CAPTION device (S& N) from 10 healthy volunteers.

Results: Combining PRC with BGSs increased hBMSC proliferation (p< 0.05) and decreased ALP activity (p< 0.05) compared to DBM or â-TCP (GenOS, S& N) alone, but had no effect on allograft following 3 and 5 days treatment. After 21 days PRC enhanced mineralisation compared to all BGSs alone (16%–56%). Compared to PRC alone addition of DBM and allograft increased proliferation (p< 0.05), decreased ALP activity (p< 0.005) and decreased mineralisation (p< 0.005). TGF-â, VEGF and BMP-2 release from PRC was unaffected when combined with DBM but PDGF-AB release was reduced by 50%.

Conclusions: Combining PRC with the majority of BGSs enhanced cell proliferation and decreased osteoblastic differentiation at early time points but increased total mineralisation compared to the BGSs alone. However, compared to PRC alone combining DBM or allograft with PRC reduced mineralisation. One potential explanation for the effects of combining PRC with DBM is altered growth factor release profiles compared to the components alone.