Assessment of stem cell viability in the initial healing period in rabbits with a cranial bone defect according to the type and form of scaffold.

PURPOSE: Increased bone regeneration has been achieved through the use of stem cells in combination with graft material. However, the survival of transplanted stem cells remains a major concern. The purpose of this study was to evaluate the viability of transplanted mesenchymal stem cells (MSCs) at an early time point (24 hours) based on the type and form of the scaffold used, including type I collagen membrane and synthetic bone. METHODS: The stem cells were obtained from the periosteum of the otherwise healthy dental patients. Four symmetrical circular defects measuring 6 mm in diameter were made in New Zealand white rabbits using a trephine drill. The defects were grafted with 1) synthetic bone (ß-tricalcium phosphate/hydroxyapatite [ß-TCP/HA]) and 1×105 MSCs, 2) collagen membrane and 1×105 MSCs, 3) ß-TCP/HA+collagen membrane and 1×105 MSCs, or 4) ß-TCP/HA, a chipped collagen membrane and 1×105 MSCs. Cellular viability and the cell migration rate were analyzed. RESULTS: Cells were easily separated from the collagen membrane, but not from synthetic bone. The number of stem cells attached to synthetic bone in groups 1, 3, and 4 seemed to be similar. Cellular viability in group 2 was significantly higher than in the other groups (P<0.05). The cell migration rate was highest in group 2, but this difference was not statistically significant (P>0.05). CONCLUSIONS: This study showed that stem cells can be applied when a membrane is used as a scaffold under no or minimal pressure. When space maintenance is needed, stem cells can be loaded onto synthetic bone with a chipped membrane to enhance the survival rate.

Evaluation of the bisphosphonate effect on stem cells derived from jaw bone and long bone rabbit models: A pilot study.

BACKGROUND AND OBJECTIVE: Bisphosphonates have been widely used and the number of patients experiencing medication-related osteonecrosis of the jaw (MRONJ) has been increasing. This study was designed to evaluate the effect of zoledronate on stem cells derived from different tissues. DESIGN: Stem cells derived from four different tissues were compared using rabbit models (JPO: periosteum from the jaw bone (mandible), JBM: bone marrow from the jaw bone, LPO: periosteum from long bone (tibia), and LBM: bone marrow from long bone). Stem cells were grown in the presence of zoledronate at final concentrations ranging from 10-6M to 10-10M. Morphology was viewed under an inverted microscope, and the analysis of cell proliferation was performed using a Cell Counting Kit-8 (CCK-8) on days 1, 2, 4, and 7. RESULTS: The CCK-8 results for LBM showed that the increase of CCK-8 values was correlated with a longer incubation time. Compared to the untreated control, growth in the presence of zoledronate at 10-10M and 10-8M resulted in decreased CCK-8 values for LBM on day 7 (P<0.05). The CCK-8 results for JBM, LPO, and JPO on days 1, 2, 4, and 7 showed that the presence of zoledronate did not produce statistically significant changes compared with the untreated control. CONCLUSION: Zoledronate in the tested concentrations from JBM, LPO, and JPO did not produce noticeable alterations in the viability of mesenchymal stem cells. This in vitro experiment suggests that the occurrence of MRONJ solely in the oral cavity is not due to differences in the cellular proliferation of stem cells in the response to zoledronate.

Graphitized-Carbon-Nanofiber Paper-Enzyme Electrode Fabrication Through Non-Covalent Modification for Enzyme Biofuel Cell Application.

Carbon nanofibers are an emerging smart material that are promising for use as a biosensor and a biofuel cell transducer material due to their morphological and electrochemical characteristics. In particular, graphitized carbon nanofibers possess unique structures of graphite-like edges within their high surface area that provide a large active site for enzyme attachment. For a specific application such as a biofuel cell, which requires highly stable electrical communication and electricity generation, non-covalent enzyme immobilization using bifunctional molecule is suggested as an appropriate approach because it does not change the carbon hybridization from sp2 to sp3 as covalent immobilization by acid treatment does. Graphitized carbon-nanofiber paper (GCNFp) electrode were fabricated through dispersion-filtration method in which glucose oxidase as model enzyme were immobilized by a bifunctional molecule that forms π-π stacking of the pyrene moiety with the nanofiber wall coupled by a reactive end-amine reaction. This system provides a practical enzyme-electrode hybrid that facilitates comparatively faster enzyme-electrode electrical communication than other system using similar material, as calculated from the heterogeneous electron-transfer rate constant (K(s)) which was 5.45 s(-1).