CREATION OF AN EXPERIMENTAL “IN VITRO” BONE MODEL FOR THE STUDY AND DIAGNOSIS OF BISPHOSPHONATE-ASSOCIATED JAWBONE OSTEOMYELITIS.

The aim of the project is to establish an experimental “in vitro” bone model for the study and diagnosis of bisphosphonate-associated jawbone osteomyelitis, in order to:
1-determine the role of nitrogen-containing bisphosphonates in the pathogenesis of jawbone osteomyelitis;
2-identify the peculiar histomorphologic and histomorphometric features of disease, if any.

Methods:

1. quantitative analysis of the bone turnover and the anti-osteoclastic activity of amino-bisphosphonates by:

• Immunohistochemistry (Tunel method for apoptosis, Trap -tartrate resistant acid phosphatase- and ED1 staining), of serial samples of osteomyelitic bone, osteonecrotic bone and hystologically healthy bone obtained from patients suffering from amino-bisphosphonates jawbone osteomyelitis, who undergo surgical treatment.

• Histomorphometric: determination of the structure and micro-architecture of the bone previously exposed to amino-bisphosphonates from serial samples of osteomyelitic bone, osteonecrotic bone and hystologically healthy bone, obtained from patients suffering from amino-bisphosphonates jawbone osteomyelitis, who undergo surgical treatment.

2. quantitative analysis of the anti-angiogenic activity of amino-bisphosphonates by:
• Immunohistochemistry (anti VEGF-2 receptor antibodies) of serial samples of osteomyelitic bone, osteonecrotic bone and hystologically healthy bone, obtained from patients suffering from amino-bisphosphonates jawbone osteomyelitis, who undergo surgical treatment.

Expected results:
1. Amino-bisphosphonates do not cause gross metabolic modifications of the jawbone structure under normal conditions. Bone turnover is normal.
2. recruitment of mature osteoclasts occurs in the osteomyelitic bone, the majority of them being inactivated and apoptotic, whilst osteoclastic precursor cells being reduced. Bone remodeling is definitely inhibited.
3. Amino-bisphosphonates do not cause any angiogenetic modification of the jawbone structure under normal conditions.
4. Angiogenesis is altered in the osteomyelitic bone, in that the vessels are obliterated and congested. Neoangiogenesis is somehow reduced due to direct inhibition of vessels formation caused by amino-bisphosphonates.