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Ann. N.Y. Acad. Sci., Annals PrePrint, published online ahead of print July 26, 2007 doi: 10.1196/annals.1402.038 Copyright © 2007 by the New York Academy of Sciences description
1 Periodontology, Tufts University School of Dental Medicine, One Kneeland Street, Boston, Massachusetts, 02111, United States 2 Oral and Maxillofacial Pathology, Tufts University School of Dental Medicine, One Kneeland Street, Boston, Massachusetts, 02111, United States 3 Biomedical Engineering, Tufts University, Boston, Massachusetts, United States; Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts, 02155, United States
* To whom correspondence should be addressed. E-mail: petros.damoulis{at}tufts.edu. PrePrint Abstract
Bone marrow-derived mesenchymal stem cells (BMSC) are a powerful tool for tissue engineering and can be used in regeneration of bone and other tissues. Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) plays an important role in bone development and healing. We hypothesized that NO plays a role in osteogenic differentiation of BMSC cultured in three-dimensional silk scaffolds. eNOS protein was measured by Western Analysis and its activity was assessed by measuring nitrite in culture supernatants. Mineralization was evaluated through calcium deposition and the expression of genes associated with osteogenic differentiation (collagen I, RUNX2 and osteocalcin) was quantified using real-time RT-PCR. eNOS was consistently expressed with minor fluctuations, but NO production significantly increased at later time points (wk 4 and 5). Addition of a competitive NOS inhibitor (L-NAME) resulted in a modest decrease in calcium deposition, which became statistically significant in wk 5. This was preceded by a dramatic decrease in RUNX2 and osteocalcin expression in wk 4. These results support our hypothesis and implicate NO as an important player in bone tissue engineering. Key Words:
Nitric Oxide, Mesenchymal Stem Cells, Cell Differentiation, Osteogenesis, Tissue Engineering
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