Search

Bone scaffold surface characterization is important for improving cell adhesion, migration, and differentiation. In this study, bone morphogenetic protein-2 (BMP-2) was immobilized to the surface of the gelatin/hydroxyapatite composite using avidin–biotin binding system to produce a bone-tissue engineering scaffold. Firstly, hydroxyapatite particles reacted with hexamethylene diisocyanate and then the terminal group was converted into a primary amine group. Avidin was then immobilized on the surfaces of hydroxyapatite particles using N-ethyl-N′-(3-(dimethylamino)propyl) carbodiimide and N-hydroxysuccinimide as coupling agents. Gelatin was blended with avidin-modified hydroxyapatite and pure hydroxyapatite to obtain gelain/hydroxyapatite composite. The composite was then cross-linked with glutaraldehyde. Finally, biotin-conjugated BMP-2 was immobilized on the surface of the composite via avidin–biotin binding. In vitro study indicated that BMP-2-immobilized composite film had a higher ALP activity than that composite film without BMP-2. The composite scaffolds were then implanted into rabbit skulls to check bone-tissue regeneration. Ultrasound and micro-CT scans demonstrated that neovascularization and new bone formation in the BMP-2-immobilized composite scaffolds were higher than those in composite scaffolds without BMP-2. Histological evaluation result was similar to that of the micro-CT. Therefore, the surface immobilization of BMP-2 could effectively improve osteogenesis in the gelatin/hydroxyapatite composite scaffold.

Gelatin nanofibers (GNs) prepared by electrospinning were cross-linked with glutaraldehyde vapor to improve their water-resistant ability. After cross-linking treatment, the form of the fibers expressed no substantial change, but the average diameter of the fibers increased with increasing cross-linking time. The swelling induced by the moisture during the cross-linking process was moderated when the cross-linking time reached 45 min. The contact angle measurements confirmed that the electrospun gelatin fibers were more hydrophilic than the gelatin film (GF). Increasing the cross-linking time did not alter the hydrophilic properties of the gelatin fibers. The cell compatibility was evaluated based on 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay, scanning electron microscope and confocal microscope observations, and Western blot analysis by culturing MG-63 cells on the GFs and GNs. The nanofibrous structure fabricated by an electrospinning technique was found to enhance cell adhesion and proliferation. This process is a cost-effective simulation of GN structures’ promising applications on scaffold preparation for tissue engineering.

Background. The timing of electrical stimulation (ES) after peripheral nerve transection may enhance axonal regeneration and functional recovery. Objective. The authors examined whether percutaneous ES at 1 mA and 2 Hz affects regeneration between the proximal and distal nerve stumps. Methods. Four groups of adult rats were subjected to sciatic nerve section followed by repair using silicone rubber conduits across a 10-mm gap. All groups received ES for 15 minutes every other day for 2 weeks. Stimulation was initiated on day 1 following the nerve repair for group A, day 8 for group B, and day 15 for group C. The control group D received no ES. Results. At 6 weeks after surgery in groups B and C, histological evaluations showed a significantly higher number of regenerated myelinated fibers in the sciatic nerve, and the electrophysiological results showed higher levels of reinnervation with relatively larger mean values of amplitudes, durations, and areas of compound muscle action potentials compared with A and D. Conclusion. A short delay in the onset of ES may improve the recovery of a severe peripheral nerve injury, which should be considered as a way of augmenting rehabilitative approaches.

Polylactic acid (PLA) is a polymer that has good biocompatibility, good biodegradability and excellent mechanical properties. The modulus of elasticity and the thermoplastic ability of PLA can satisfy the need for the carrier material of the cell to grow in bone tissue engineering, such as in regeneration and repair of bone and cartilage tissue. The PLA multifilament was twisted using different twisting parameters and a rotor-twister to fabricate United States Pharmacopoeia (U.S.P.) size 5-0 and 7-0 surgical sutures. The best tensile strengths were 3.1 and 12.3 N, and the coefficients of variation were 3.70% and 1.75%. The PLA suture was then scoured with 1 wt% sodium hydroxide to eliminate impurities, and the knot-pull strengths decreased to 1.66 and 6.84 N for 7-0 and 5-0 PLA sutures, respectively, but still conforming to the U.S.P. knot-pull strength standard. An in vitro hydrolysis test was performed at 37°C by immersing 5-0 PLA suture in physiological saline (0.9 wt% NaCl aqueous solution); the knot-pull strength decreased by 12% after 28 days.

In this study, different Tencel/cotton ratios and needle punching densities were used to make Tencel/cotton nonwoven, which was then coated with chitosan to fabricate a double-layer wound dressing. The nonwoven-chitosan dressing, prepared by using the immersion-precipitation phase-inversion method, had properties that could control the evaporation water loss, promote the fluid drainage, and inhibit the invasion of exogenous micro-organisms. These results indicated that the nonwoven-chitosan membrane could be a potential material for use as a wound dressing.

Background: Longan is a fruit tree known to contain many phenolic components, which are capable of protecting people from oxidative damage through an anti-inflammatory mechanism. It may be also worthwhile to study the effect on lowering uric acid activity. Materials and Methods: This study investigates the lowering of uric acid using longan extracts, including flowers, pericarps, seeds, leaves, and twigs, on potassium-oxonate-induced hyperuricemia mice and its inhibitory actions against xanthine oxidase (XO) activities. Results: The findings revealed that ethyl acetate fraction of longan extracts exhibited strong XO-inhibitory activity, and the flower extracts (IC50 = 115.8 μg/mL) revealed more potent XO-inhibitory activity to those of pericarps (118.9 μg/mL), twigs (125.3 μg/mL), seeds (262.5 μg/mL), and leaves (331.1 μg/mL) in vitro. In addition, different dosages of longan extract (50–100 mg/kg) were administered to hyperuricemic mice. The lowering effect of longan extracts on uric acid at 75 mg/kg markedly reduced plasma uric acid levels in decreasing order: Flowers (80%) > seeds (72%) > pericarps (64%) > twigs (59%) > leaves (41%), compared with allopurinol (89%). Finally, 10 isolated phytochemicals from longan flowers were then examined in vitro. The results indicated that proanthocyanidin A2 and acetonylgeraniin A significantly inhibited XO activity in vitro. This is the first report providing new insights into the urate-reducing effect of phenolic dimer and hydrolyzable tannin, which can be developed to potential hypouricemic agents. SUMMARY Longan flower extracts possess more potent XO-.inhibitory activity than pericarps, twigs, seeds, and leaves in vitro The lowering effect of longan flowers and seeds extracts markedly reduced plasma uric acid levels as compared to allopurinol in vivo The extract proanthocyanidin A2 and acetonylgeraniin A were demonstrated potent XO inhibitory activity in vitro. Abbreviations used: PO: Potassium-oxonate, XO: xanthine oxidase, HE: n-hexane, EA: ethyl acetate, i.p.: intraperitoneal, PBS: phosphate-buffered saline, AP: allopurinol, PUA: plasma uric acid.

Background. Electrical stimulation of damaged peripheral nerve may aid regeneration. Objective. The purpose of this study was to determine whether 1 mA of percutaneous electrical stimulation at 1, 2, 20, or 200 Hz augments regeneration between the proximal and distal nerve stumps. Methods. A10-mm gap was made in rat sciatic nerve by suturing the stumps into silicone rubber tubes. A control group received no stimulation. Starting 1 week after transection, electrical stimulation was applied between the cathode placed at the distal stump and the anode at the proximal stump every other day for 6 weeks. Results. Higher frequency stimulation led to less regeneration compared to lower frequencies. Quantitative histology of the successfully regenerated nerves revealed that the groups receiving electrical treatment, especially at 2 Hz, had a more mature structure with a smaller cross-sectional area, more myelinated fibers, higher axon density, and higher ratio of blood vessel to total nerve area compared with the controls. Electrophysiology showed significantly shorter latency, longer duration, and faster conduction velocity. Conclusion. Electrical stimulation can have either a positive or negative impact on peripheral nerve regeneration. Clinical trials that combine stimulation with rehabilitation must determine the parameters that are most likely to be safe and effective.

Silicone rubber chambers filled with collagen containing ginsenoside Rb1 (GRb1) were used to repair lesioned rat sciatic nerves with 15-mm gaps between stumps. Six weeks after implantation, histology of the nerve regenerated in the chambers filled with GRb1 and collagen contained larger axons than those in the chambers with collagen only. This study showed that the GRb1 could exert a positive influence on nerve regeneration when using silicone rubber tubes.