Bone-Conditioned Medium Obtained From Calvaria, Mandible, and Tibia Cause an Equivalent TGF-β1 Response In Vitro

Bones with different embryological origin and mode of ossification are supposed to vary in their capacity for supporting graft consolidation. The aim of the current pilot study was to assess the TGF-β1 activity of bone chips obtained from distinct anatomic locations. Conditioned medium was prepared from bone chips harvested from pig calvaria, mandible, and tibia. Human oral fibroblasts were exposed to bone-conditioned medium (BCM) followed by reverse transcriptase polymerase chain reaction of the TGF-β1 target genes. Also an immunoassay for interleukin 11 (IL-11) and TGF-β1 was performed. The impact of BCM on alkaline phosphatase activity was determined with murine MC3T3-E1 osteogenic cells. The authors report here that BCM contains TGF-β1 in the ng/mL range. Bone chips prepared from pig calvaria, mandible, and tibia femur had a similar capacity for increasing the expression of the TGF-β1 target genes IL-11, NOX4, and PRG4. Correspondingly, immunoassays revealed similar production of IL-11 by human oral fibroblasts. Furthermore, conditioned medium obtained from the 3 bones decreased alkaline phosphatase activity in MC3T3-E1 osteogenic cells. These preliminary data demonstrate that particulated bone grafts, regardless of embryological origin, mode of ossification and morphology, release a similar TGF-β1 activity.