No abstract

Our results indicate that SWCNT is a feasible material to deliver HY to bone defects. Importantly, the functionalization of SWCNT with HY preserved the beneficial biological properties of HY in the healing process, thereby suggesting that HY-SWCNT scaffolds are potentially useful biomaterials for the restoration of bone defects.

Tissue engineering has emerged as a novel treatment for replacement of lost bone tissue. This study evaluated the effects of a chitosan-gelatin scaffold seeded with bone marrow mesenchymal stem cells (BMMSCs) in the healing process of tooth sockets in rats. BMMSCs isolated from transgenic rats expressing enhanced green fluorescent protein (eGFP) were expanded and seeded on a chitosan-gelatin scaffold. These constructs were cultured for three days and characterized by scanning electronic microscopy (SEM) and energy dispersion spectroscopy (EDS). Receptor rats received the implant in the left sockets, after upper first-molar extraction. Right alveoli served as control. Animals were sacrificed at days 5, 21, and 35 post-graft for examination. Morphometry demonstrated increased bone mineralization after 21 and 35 days in transplanted sockets. Migration, differentiation, and fate of eGFP-labeled BMMSCs were monitored by immunohistochemistry. Tartrate-resistant acid phosphatase staining (TRAP) was carried out at 21 days, to identify the involvement of osteoclastic cells in the scaffold resorption. The biomaterial was resorbed by TRAP-negative giant cells in a typical foreign body reaction. Immunohistochemical findings showed that BMMSCs contributed to bone, epithelial, and vascular repair. Together, results indicate that BMMSCs loaded in the chitosan-gelatin scaffold is a strategy for tissue development in bone engineering.

Our results indicate that HY and HY-CNT restore bone repair in the tooth sockets of diabetic rats, suggesting that these biomaterials are potential adjuvant therapies for the management of diabetes.

The aim of this study was to evaluate the effects of sodium hyaluronate (HY), single-walled carbon nanotubes (SWCNTs) and HY-functionalized SWCNTs (HY-SWCNTs) on the behavior of primary osteoblasts, as well as to investigate the deposition of inorganic crystals on titanium surfaces coated with these biocomposites. Primary osteoblasts were obtained from the calvarial bones of male newborn Wistar rats (5 rats for each cell extraction). We assessed cell viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay and by double-staining with propidium iodide and Hoechst. We also assessed the formation of mineralized bone nodules by von Kossa staining, the mRNA expression of bone repair proteins, and the deposition of inorganic crystals on titanium surfaces coated with HY, SWCNTs, or HY-SWCNTs. The results showed that treatment with these biocomposites did not alter the viability of primary osteoblasts. Furthermore, deposition of mineralized bone nodules was significantly increased by cells treated with HY and HY-SWCNTs. This can be partly explained by an increase in the mRNA expression of type I and III collagen, osteocalcin, and bone morphogenetic proteins 2 and 4. Additionally, the titanium surface treated with HY-SWCNTs showed a significant increase in the deposition of inorganic crystals. Thus, our data indicate that HY, SWCNTs, and HY-SWCNTs are potentially useful for the development of new strategies for bone tissue engineering.

It has been reported that carbon nanotubes (CNTs) serve as nucleation sites for the deposition of bone matrix and cell proliferation. Here, we evaluated the effects of multi-walled CNTs (MWCNTs) on bone repair of rat tibiae. Furthermore, because sodium hyaluronate (HY) accelerates bone restoration, we associated CNTs with HY (HY-MWCNTs) in an attempt to boost bone repair. The bone defect was created by a 1.6-mm-diameter drill. After 7 and 14 days, tibiae were processed for histological and morphometric analyses. Immunohistochemistry was used to evaluate the expression of vascular endothelial growth factor (VEGF) in bone defects. Expression of osteocalcin (OCN), bone morphogenetic protein-2 (BMP-2), and collagen I (Col I) was assessed by real-time PCR. Histomorphometric analysis showed a similar increase in the percentage of bone trabeculae in tibia bone defects treated with HY and HY-MWCNTs, and both groups presented more organized and thicker bone trabeculae than nontreated defects. Tibiae treated with MWCNTs or HY- MWCNTs showed a higher expression of VEGF. Treatment with MWCNTs or HY-MWCNTs increased the expression of molecules involved in the bone repair process, such as OCN and BMP-2. Also, HY- and MWCNT-treated tibiae had an increased expression of Col I. Thus, it is tempting to conclude that CNTs associated or not with other materials such as HY emerged as a promising biomaterial for bone tissue engineering.