Characterization of human bone cells derived from the maxillary alveolar ridge.

In this study, we have characterized bone cell cultures derived from the human maxillary alveolar ridge, which could be a potential cell source for tissue engineering of the severely resorbed maxilla. From 10 individuals, an osseous core was obtained. Without the use of collagenase, 10 explant cultures were established and the morphology of the cells (human maxilla-derived cells (hMDCs)) was studied with light microscopy (LM). Explant cultures were analyzed by flow cytometry with respect to size, granularity and surface marker expression. Fluorochrom-conjugated monoclonal antibodies (CD13, CD31, CD44, CD90 or CD73) were used. hMDCs were cultured in standard medium (SCM) or osteoinductive medium (OIM) for 21 days and analyzed for the presence of alkaline phosphatase (ALP) and calcium deposits (Von Kossa). Furthermore, osteogenic gene expression (osteocalcin [OC], ALP, collagen type 1) were analyzed by reverse transcription polymerase chain reaction (RT-PCR). LM demonstrated that hMDCs had a polygonal morphology containing a central nucleus with two to three nucleoli. Size/granularity analysis revealed differences between individuals. Immunophenotypically, these cells were positive for CD13, CD44, CD90 and CD73 while negative for CD31. Cells cultured in SCM for 21 days showed moderate ALP staining and many calcium deposits. Culturing cells in OIM for 21 days significantly increased both ALP staining and the number of calcium deposits. RT-PCR demonstrated expression of osteogenic marker genes and the ability to upregulate osteocalcin and ALP in response to osteogenic inducers. To our knowledge, it is the first time that surface marker expression has been studied on bone cells originating from this site. Cells were positive for markers characteristic for immature mesenchymal stem cells and had osteogenic differentiation capability. This study indicates that cells derived from maxillary biopsies could be a potential cell source for bone tissue engineering.