Fabrication and in vivo osteogenesis of biomimetic poly(propylene carbonate) scaffold with nanofibrous chitosan network in macropores for bone tissue engineering.

A biomimetic poly(propylene carbonate) (PPC) porous scaffold with nanofibrous chitosan network within macropores (PPC/CSNFs) for bone tissue engineering was fabricated by a dual solid-liquid phase separation technique. PPC scaffold with interconnected solid pore wall structure was prepared by the first phase separation, which showed a high porosity of 91.9% and a good compressive modulus of 14.2 ± 0.56 MPa, respectively. By the second phase separation, nanofibrous chitosan of 50-500 nm in diameter was formed in the macropores with little influence on the pore structure and the mechanical properties of PPC scaffold. The nanofibrous chitosan content was calculated to be 9.78% by elemental analysis. After incubation in SBF for 14 days, more apatite crystals were deposited on the pore surface as well as the nanofibrous chitosan surface of PPC/CSNFs scaffold compared with PPC scaffold. The in vitro culture of bone mesenchymal stem cells showed that PPC/CSNFs scaffold exhibited a better cell viability than PPC scaffold. After implantation in rabbits for 16 weeks, the defect was entirely repaired by PPC/CSNFs scaffold, as opposed to the incomplete healing for PPC scaffold. It indicated that PPC/CSNFs scaffold showed a faster in vivo osteogenesis rate than PPC scaffold. Hereby, PPC/CSNFs scaffold will be a potential candidate for bone tissue engineering.

Preparation and properties of biomimetic porous nanofibrous poly(L-lactide) scaffold with chitosan nanofiber network by a dual thermally induced phase separation technique.

A biomimetic nanofibrous poly(L-lactide) scaffold decorated by chitosan nanofiber network inside the macropores was fabricated using a dual thermally induced phase separation technique. The first phase separation was used to build a nanofibrous poly(L-lactide) scaffold with interconnected macropores, where chitosan nanofibers about 500nm in diameter were incorporated via the second phase separation. The content of nanofibrous chitosan was determined to be 5.76 in weight percentage by elemental analysis. The composite scaffold showed the highest protein adsorption of 7225±116 µg/cm(3) and the most hydroxyapatite crystal deposition in the mineralization. Compared with non-nanofibrous poly(L-lactide) scaffold, nanofibrous poly(L-lactide) scaffold exhibited a much faster degradation, but it could be restrained by the introduced chitosan nanofibers. The bone mesenchymal stem cell culture results indicated that the cells would rather attach and stretch along the chitosan nanofibers in the composite scaffold that showed the highest viability and the best cytocompatibility may be attributed to the biomimetic nanofibrous network and good cell affinity of chitosan nanofibers.

[A comparative study between humeral head prosthesis replacement and internal fixation for treatment of comminuted proximal humeral fractures].

OBJECTIVE: To compare the clinical efficacies of humeral head prosthesis and internal fixation in the treatment of comminuted proximal humeral fractures. METHODS: The clinical data were analyzed for the patients with comminuted proximal humeral fractures undergoing surgeries for humeral head replacement or open reduction plus internal fixation in our hospital between January 2002 and January 2009. Constant scores were used to determine the excellent clinical outcome rates in the two groups, and the operating time, blood loss and postoperative motor scores of the shoulder were compared. RESULTS: Forty patients in the humeral head replacement group were evaluated. According to the Constant scores, excellent outcomes were achieved in 16 patients, good outcomes in 18 patients, moderate in 3 patients, and poor in 3 patients, with an excellent outcome rate of 85%. In the 40 cases receiving open reduction plus internal fixation, excellent outcomes were achieved in 11 cases, good in 13 cases, moderate in 8 cases, and poor in 8 cases, with an excellent clinical outcome rate of 60%. Compared with open reduction plus internal fixation, humeral head replacement was associated with shortened operating time, reduced blood loss and better motor function recovery of the shoulder. CONCLUSIONS: Replacement of humeral head prosthesis produces better clinical outcomes than open reduction and internal fixation in patients with comminuted proximal humeral fractures, and can promote the short-term functional recovery of the shoulder with minimal surgical complications.

Synthesis of novel liquid crystal compounds and their blood compatibility as anticoagulative materials.

The objective of this study was to synthesize new types of cholesteric liquid crystal compounds and study the anticoagulative properties of their composite membranes. Three kinds of cholesteric liquid crystal compounds were synthesized and characterized by infrared spectroscopy, differential scanning calorimetry and optical polarizing microscope. The polysiloxane, as a substrate, was blended with three liquid crystal compounds and was then used as membranes. The anticoagulative property of different polysiloxane liquid crystal composite membranes was identified by the blood compatibility tests. Three cholesteryl liquid crystals synthesized in this work contained hydrophilic soft chains and presented iridescent texture owned by cholesteric liquid crystals in the range of their liquid crystal state temperature, but only cholesteryl acryloyl oxytetraethylene glycol carbonate was in the liquid crystal state at body temperature. When liquid crystals were blended with polysiloxane to form polysiloxane/liquid crystal composite membranes, the haemocompatibility of these membranes could be improved to some extent. The blood compatibility of composite membranes whose hydrophilic property was the best was more excellent than that of other composite membranes, fewer platelets adhered and spread, and showed little distortion on the surface of materials.