Background: It has been frequently reported that culture-expanded mesenchymal stem cells from bone marrow of healthy donors can be induced to differentiate to osteocytic lineage. This study examined the potential for osteogenic differentiation of mesenchymal stem cells obtained from two patients with myeloproliferative disorders.
Methods: Mesenchymal stem cells were derived from bone marrow aspirates obtained in an outpatient clinic from two patients, one with polycythemia vera and the other with essential thrombocythemia. Nucleated bone marrow cells were directly cultured in flasks. Adherent fibroblastic cells in monolayers were isolated by removing nonadherent cells during medium changes. Osteogenic differentiation was induced in expanded adherent cells for 2 weeks in osteogenic medium containing 100 nmol/L dexamethasone, 10 mmol/L beta-glycerophosphate, and 0.05 mmol/L L-ascorbic acid-2-phosphate. Osteogenic differentiation was evaluated by alkaline phosphatase staining and determination of calcium in deposited minerals on culture plates. The expression of osteopontin mRNA was determined by reverse transcription-polymerase chain reaction.
Results: After induction in osteogenic medium, the expression of alkaline phosphatase in mesenchymal stem cells became more intense. Induced alkaline phosphatase-positive cells assumed an irregular shape with multiple spiculate projections, while uninduced alkaline phosphatase-positive cells had a flattened polygonal shape or were elongated. Calcium deposition on the plates of induced cells was 0.39 +/- 0.03 mumol/well in cells from the patient with polycythemia vera and 0.54 +/- 0.03 mumol/well in cells from the patient with essential thrombocythemia, but was not detectable in uninduced cells from either patient. Induction by osteogenic medium markedly increased the expression of osteopontin mRNA in stem cells derived from both patients.
Conclusions: In this study, mesenchymal stem cells obtained from aspiration of bone marrow in patients with myeloproliferative disorders were expanded by culture. After osteogenic induction, these cells were shown to be able to differentiate into osteocytic lineage in vitro.