Embolic effects of Bletilla striata microspheres in renal artery and transplanted VX2 liver tumor model in rabbits.

OBJECTIVES: To evaluate the characteristics of Bletilla striata microspheres (BSMs) and its effects as an embolic agent in a rabbit model. METHODS: BSMs were prepared with an emulsification-cool condensation-chemical cross-linking method. The characteristics of BSMs in vitro were observed. Embolization experiments were performed in renal artery of rabbit and in a rabbit liver VX2 carcinoma model. Seventy-two New Zealand rabbits were divided into 2 groups, and the right renal artery was embolized with BSMs (200 µm in diameter) in the experimental group and with polyvinyl alcohol (PVA) of the same size in the control group. The pathological findings were examined with hematoxylin-eosin and Masson stainings. Liver and renal functions were tested before and after embolization. VX2 tumor was transplanted in 15 New Zealand rabbits, which were randomly divided into 3 groups (n=5). Group A were treated with saline, group B with a mixture of doxorubicin and lipiodol, and group C with hepatic arterial infusion of BSMs (200 µm in diameter). Tumor growth rate was evaluated by magnetic resonance imaging scan. Apoptosis-related factors (bax, bcl-2) and tumor vascular endothelial cell growth factor (VEGF) were evaluated through immunohistochemical staining. RESULTS: The characteristics of BSMs in vitro were in full compliance with the requirements for use in interventional procedures. In the renal artery embolization experiment, after BSMs intervention, it was more difficult to form collateral circulation than that with PVAs, and the kidney manifested atrophy and calcification. There were no significant difference of liver and renal functions in rabbits between groups. In the liver VX2 carcinoma embolization experiment, compared with group A, the growth rate of VX2 liver tumor and Bcl-2 levels was reduced, while apoptosis index, Bax, and VEGF were increased in group B (P<0.05). There were no significant difference between groups B and C (P>0.05). CONCLUSIONS: The characteristics of BSMs in vitro and in vivo meet the requirements for its use as an embolic agent in interventional approaches.

In vitro and in vivo efficacies of teicoplanin-loaded calcium sulfate for treatment of chronic methicillin-resistant Staphylococcus aureus osteomyelitis.

The in vitro and in vivo therapeutic efficacies of teicoplanin-loaded calcium sulfate (TCS; 10% [wt] teicoplanin) were investigated in a rabbit model of chronic methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. The in vitro elution characteristics of teicoplanin from TCS pellets were realized by carrying out an evaluation of the release kinetics, recovery rate, and antibacterial activity of the released teicoplanin. Chronic osteomyelitis was induced by inoculating 10(7) CFU of a MRSA strain into the tibial cavity of rabbits. After 3 weeks, the animals were treated by debridement followed by implantation of TCS pellets in group 1, calcium sulfate (CS) pellets alone in group 2, and intravenous (i.v.) teicoplanin (6 mg/kg of body weight every 12 h for three doses and then every 24 h up to 4 weeks) in group 3. Animals in group 4 were left untreated. After 6 weeks, the efficacy of the osteomyelitis treatment was evaluated by hematological, radiological, microbiological, and histological examinations. In vitro elution studies showed sustained release of teicoplanin at a therapeutic level over a time period of 3 weeks. The released teicoplanin maintained its antibacterial activity. In vivo, the best therapeutic effect was observed in animals treated with TCS pellets, resulting in significantly lower radiological and histological scores, lower positive rates of MRSA culture and bacterial load, and excellent bone regeneration compared with those treated by CS alone or i.v. teicoplanin, without any local or systemic adverse effects. TCS pellets are an effective alternative to i.v. teicoplanin for the treatment of chronic MRSA osteomyelitis, particularly because teicoplanin is delivered locally while the TCS pellets simultaneously promote bone defect repair.