ObjectiveThe antifriction and antiwear effects of gelatin nanoparticles (GLN-NP) on artificial joint materials in bionic joint lubricant were investigated to provide a theoretical basis for the development of new bionic joint lubricant. MethodsGLN-NP was prepared by cross-linking collagen acid (type A) gelatin with glutaraldehyde by acetone method, and the particle size and stability of GLN-NP were characterized. The biomimetic joint lubricants with different concentrations were prepared by mixing 5, 15, and 30 mg/mL GLN-NP with 15 and 30 mg/mL hyaluronic acid (HA), respectively. The friction reduction and antiwear effects of the biomimetic joint lubricants on zirconia ceramics were investigated on a tribometer. The cytotoxicity of each component of bionic joint lubricant on RAW264.7 mouse macrophages was evaluated by MTT assay. ResultsThe particle size of GLN-NP was about 139 nm, and the particle size distribution index was 0.17, showing a single peak, indicating that the particle size of GLN-NP was uniform. In complete culture medium, pH7.4 PBS, and deionized water at simulated body temperature, the particle size of GLN-NP did not change more than 10 nm with time, indicating that GLN-NP had good dispersion stability and did not aggregate. Compared with 15 mg/mL HA, 30 mg/mL HA, and normal saline, the friction coefficient, wear scar depth, width, and wear volume were significantly reduced by adding different concentrations of GLN-NP (P<0.05); there was no significant difference between different concentrations of GLN-NP (P>0.05). Biocompatibility test showed that the cell survival rate of GLN-NP, HA, and HA+GLN-NP solution decreased slightly with the increase of concentration, but the cell survival rate was more than 90%, and there was no significant difference between groups (P>0.05). ConclusionThe bionic joint fluid containing GLN-NP has good antifriction and antiwear effect. Among them, GLN-NP saline solution without HA has the best antifriction and antiwear effect.
Objective To evaluate the effects and the molecular mechanism of Liuwei dihuang pills in preventing steroid-induced osteonecrosis of the femoral head (ONFH) so as to provide an expremental basis for preventing ONFH cl inically. Methods Thirty-six adult Kunming mice (weighing 40-50 g, 46 g on average) were randomly divided into three groups (n=12): group A (control group), group B (model group) and group C (prevention group). In groups B and C, ONFHmice models were produced by intraperitoneal injection of horse serum at first (10 mL/kg) and a second injection of horse serum intraperitoneally (5 mL/kg) and prednisolone intramuscularly [45 mL/(kg?day), for 5 days] 2 weeks later. At the same time, the mice in group C were given Liuwei dihuang pills intragastrically [2 g/(kg?day)] and were given normal sal ine [10 mL/(kg?day)] in group B. In group A, mice were given normal sal ine intramuscularly and intragastrically as controls. The animals were sacrificed 2, 4, and 8 weeks after first treatment with prednisone, and femoral heads and l ivers were harvested to do histopathology analysis and apoptosis assay. Results Other mice survived throughout the experiment period except two death at 7 and 11 days after second injection of horse serum intraperitoneally in group B and one death at 24 hours after second injection of horse serum intraperitoneally in group C. The appearance and shape of the femoral head and the surface of cartilages were all normal. The histological observation showed: normal structures of l iver and femoral head were seen in group A at each time point; swell ing l iver cells with small fat vacuole, unclear structure of hepatic cords and narrower sinus hepaticus were seen, the bone trabeculae of femoral head was thin, sparse and collapsed in some regions and the changes became more obvious with time in group B; group C had similar results to group A. The percentage of empty osteocyte lacunae was significantly higher in group B than in groups A and C (P lt; 0.01). The osteoprotegrin expression significantly decreased and the osteoprotegrin l igand expressionsignificantly increased in group B when compared with groups A and C (P lt; 0.01). Apoptosis analysis showed that the apoptosis index in group B was significantly higher than that in groups A and C (P lt; 0.01). Conclusion Liuwei dihuang pills can prevent steroid-induced ONFH by improving l ipid metabol ism, releiving bone lesion, and protecting against cell death.
