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Purpose: Several scaffolds and cell sources are being investigated for cartilage regeneration. The aim of the study was to prepare nanocellulose-based thermosensitive injectable hydrogel scaffolds and assess their potential as 3D scaffolds allowing the chondrogenic differentiation of embedded human dental pulp stem and progenitor cells (hDPSCs). Materials and Methods: The hydrogel-forming solutions were prepared by adding βglycerophosphate (GP) to chitosan (CS) at different ratios. Nanocellulose (NC) suspension was produced from hemp hurd then added dropwise to the CS/GP mixture. In vitro characterization of the prepared hydrogels involved optimizing gelation and degradation time, massswelling ratio, and rheological properties. The hydrogel with optimal characteristics, NC-CS /GP-21, was selected for further investigation including assessment of biocompatibility. The chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel was investigated in vitro and compared to that of bone marrow-derived mesenchymal stem cells (BMSCs), then was confirmed in vivo in 12 adult Sprague Dawley rats. Results: The selected hydrogel showed stability in culture media, had a gelation time of 2.8 minutes, showed a highly porous microstructure by scanning electron microscope, and was morphologically intact in vivo for 14 days after injection. Histological and immunohistochemical analyses and real-time PCR confirmed the chondrogenesis ability of hDPSCs embedded in NC-CS/GP-21 hydrogel. Conclusion: Our results suggest that nanocellulose-chitosan thermosensitive hydrogel is a biocompatible, injectable, mechanically stable and slowly degradable scaffold. hDPSCs embedded in NC-CS/GP-21 hydrogel is a promising, minimally invasive, stem cell-based strategy for cartilage regeneration.

Migration of the cells in osteoblastic lineage, including preosteoblasts and osteoblasts, has been postulated to influence bone formation. However, the molecular bases that link preosteoblastic/ osteoblastic cell migration and bone formation are incompletely understood. Nck (noncatalytic region of tyrosine kinase; collectively referred to Nck1 and Nck2) is a member of the signaling adaptors that regulate cell migration and cytoskeletal structures, but its function in cells in the osteoblastic lineage is not known. Therefore, we examined the role of Nck in migration of these cells. Nck is expressed in preosteoblasts/osteoblasts, and its knockdown suppresses migration as well as cell spreading and attachment to substrates. In contrast, Nck1 overexpression enhances spreading and increases migration and attachment. As for signaling, Nck double knockdown suppresses migration toward IGF1 (insulin-like growth factor 1). In these cells, Nck1 binds to IRS-1 (insulin receptor substrate 1) based on immunoprecipitation experiments using anti-Nck and anti-IRS-1 antibodies. In vivo, Nck knockdown suppresses enlargement of the pellet of DiI-labeled preosteoblasts/osteoblasts placed in the calvarial defects. Genetic experiments indicate that conditional double deletion of both Nck1 and Nck2 specifically in osteoblasts causes osteopenia. In these mice, Nck double deficiency suppresses the levels of boneformation parameters such as bone formation rate in vivo. Interestingly, bone-resorption parameters are not affected. Finally, Nck deficiency suppresses repair of bone injury after bone marrow ablation. These results reveal that Nck regulates preosteoblastic/ osteoblastic migration and bone mass.Nck | osteoblast | migration | bone remodeling | bone repair

Objectives Single-shade composite systems are gaining popularity among clinicians due to the claimed potential of blending with different tooth structure shades while restoring the tooth. The purpose of this study was to evaluate the blending effect of two single-shade composite with different shades of conventional resin composite systems. Materials and Methods Seventy-two composite cylinders of B1, B2, A1, A2, A3, or A3.5 shade from CharmFil Plus (CP) and Filtek Universal Restorative (3M) were prepared using custom-made silicone mold. Single-shade composite OMNICHROMA (OC) or Beautifil II Enamel (BE) was placed in the center of each cylinder and polymerized. The color parameters, lightness (L*), chroma (C*), and hue (H*) of each composite were measured using a color chronometer. Furthermore, color stability of the samples was evaluated after 1-week staining challenge. Statistical Analysis Multivariant analysis was performed to evaluate the effect of material and shade on the color parameters. Multiple comparisons of the data were performed using post hoc test. The staining challenge data were analyzed using repeated measure analysis of variance and paired sample T-test. Results The multivariant analysis showed a statistically significant difference in color parameters among CP, 3M, OC, and BE (p = 0.001). Image analysis showed a visual blending effect for both OC and BE for certain shades; however, some color contrast with the darker shades was observed. The C* value of OC showed a similar pattern to CP; however, the H* of the latter was closely followed by BE. The L* value showed statistically significant difference among the shades of 3M, and in OC and BE when blended with 3M. Conclusion All four materials used in this study showed color alteration after the staining challenge. Single-shade composite can blend with only certain shades of resin composites.

Osteogenesis imperfecta (OI) is a heterogeneous genetic disorder of bone and connective tissue, also known as brittle bone disease. Null mutations in SERPINF1, which encodes pigment epithelium-derived factor (PEDF), cause severe type VI OI, characterized by accumulation of unmineralized osteoid and a fish-scale pattern of bone lamellae. Although the potent anti-angiogenic activity of PEDF has been extensively studied, the disease mechanism of type VI OI is not well understood. Using Serpinf1 (À/À) mice and primary osteoblasts, we demonstrate that loss of PEDF delays osteoblast maturation as well as extracellular matrix (ECM) mineralization. Barium sulfate perfusion reveals significantly increased vessel density in the tibial periosteum of Serpinf1 (À/À) mouse compared with wildtype littermates. The increased bone vascularization in Serpinf1 (À/À) mice correlated with increased number of CD31(+)/Endomucin(+) endothelial cells, which are involved in the coupling angiogenesis and osteogenesis. Global transcriptome analysis by RNA-Seq of Serpinf1 (À/À) mouse osteoblasts reveals osteogenesis and angiogenesis as the biological processes most impacted by loss of PEDF. Intriguingly, TGF-β signaling is activated in type VI OI cells, and Serpinf1 (À/À) osteoblasts are more sensitive to TGF-β stimulation than wild-type osteoblasts. TGF-β stimulation and PEDF deficiency showed additive effects on transcription suppression of osteogenic markers and stimulation of pro-angiogenic factors. Furthermore, PEDF attenuated TGF-β-induced expression of proangiogenic factors. These data suggest that functional antagonism between PEDF and TGF-β pathways controls osteogenesis and bone vascularization and is implicated in type VI OI pathogenesis. This antagonism may be exploited in developing therapeutics for type VI OI utilizing PEDF and TGF-β antibody.