The Schneiderian Membrane Contains Osteoprogenitor Cells: In Vivo and In Vitro Study

Recent studies successfully demonstrated induction of new bone formation in the maxillary sinus by mucosal membrane lifting without the use of any graft material. The aim of this work was to test the osteogenic potential of human maxillary sinus Schneiderian membrane (hMSSM) using both in vitro and in vivo assays. Samples of hMSSM were used for establishment of cell cultures and for histological studies. Flow cytometry analysis was performed on P-0, P-1, and P-2 cultures using established mesenchymal progenitor cell markers (CD 105, CD 146, CD 71, CD 73, CD 166), and the ability of hMSSM cells to undergo osteogenic differentiation in culture was analyzed using relevant in vitro assays. Results showed that hMSSM cells could be induced to express alkaline phosphatase, bone morphogenic protein-2, osteopontin, osteonectin, and osteocalcin and to mineralize their extracellular matrix. Inherent osteogenic potential of hMSSM-derived cells was further proven by in vivo experiments, which demonstrated the formation of histology-proven bone at ectopic sites following transplantation of hMSSM-derived cells in conjunction with an osteoconductive scaffold. This study provides the biological background for understanding the observed clinical phenomena in sinus lifting. Our results show that a genuine osteogenic potential is associated with the hMSSM and can contribute to development of successful sinus augmentation techniques.