Learning Objectives: To decribe the fate of bone patè when in contact with osteoblast cultures.

Hypothesis: The aim of the present study was to evaluate the effect of bone patè (BP) on human osteoblast differentiation by measuring cellular viability, expression of the transcription factors and the major components of extracellular matrix.

Background: Although BP has been used in ear for many years and it has been reported that after surgery BP become viable bone, the cellular mechanisms that lead to BP osteointegration have never been described.

Methods: BP obtained from 4 patients subjected to mastoidectomy and affected by middle ear and mastoid cholesteatoma was placed in contact with osteoblast-like cell (OB) cultures obtained by mastoid bone. Cell culture were treated with BP, BP with fibrin glue (BPG) and with fibrin glue alone. Cells viability was evaluated after 24 hours; After one week of treatment OBs cultured in the different conditions were subjected to the evaluation of alkaline phosphatase expression, the expression of transcription factors and bone matrix proteins by qPCR.

Results: The MTT assay revealed that, after 24 hours, OBs have increased viability when treated with BP (19% increase) and BPG (34% increase), while the treatment with fibrin glue alone did not influence this parameter. BP with and without fibrin glue increased of 97% and 94% respectively the number of alkaline phosphatase (ALP) positive cells compared to the control. Finally BP determined the upregulation of transcription factors and component of the extracellular matrix.

Conclusion: The present data show that BP has a high osteoinductive potential on human OBs, enhancing their activity.