Comparison of the Therapeutic Efficacy of Antibiotic-Loaded Polymeric Tissue Scaffold and Bone Cement in the Regeneration of Infected Bone Tissue

Abstract

Background Local antibiotic applications have been used in chronic osteomyelitis and have been defined as an adjunctive treatment method. Biodegradable materials are also used for the same purpose by adding antibiotics. The fact that it does not require additional surgery to be removed is an important advantage. In this study, we intended to develop a new biodegradable drug-loaded polymeric scaffold with good antibiotic release and compare the microbiological results with antibiotic-impregnated bone cement. Methodology A tissue scaffold containing poly(2-hydroxyethyl methacrylate) (PHEMA) was prepared in our laboratory and loaded with ertapenem and daptomycin antibiotics. The surface morphology and pore geometries of drug-loaded and unloaded scaffolds were analyzed by a scanning electron microscope under vacuum. The dose-dependent antiproliferative effects of PHEMA scaffold, drug-loaded scaffold, cement, and drug-loaded cement on osteoblast cells were investigated. To evaluate drug release kinetics, the absorbance values of the scaffold loaded with ertapenem and daptomycin were measured with the spectrometer. For microbiological tests, ertapenem and daptomycin-impregnated cement and scaffold, as well as the control scaffold and cement samples, were investigated for their antibacterial activities on Staphylococcus aureus and Klebsiella pneumoniae strains using the disc diffusion method. These microorganisms are one of the most common microorganisms in osteomyelitis. Results The efficacy of antibiotic-impregnated scaffold and cement on both gram-negative and gram-positive microorganisms was investigated. The daptomycin zone diameter in S. aureus ATCC 29233 strain was 17 mm, whereas it was 24 mm for scaffold and 22 mm for cement. Scaffold was found to be more effective than cement against S. aureus strain. The K. pneumoniae ATCC BAA-2814 strain was found to be resistant to ertapenem, but the zone diameter was 21 mm for scaffold and 20 mm for cement. Ertapenem-loaded scaffold was found to be more effective than cement. It was found that the antimicrobial activity of the scaffold was higher than cement. When we evaluated the release profiles, for the daptomycin-loaded cement group, 98% of daptomycin was cumulatively released within 30 minutes, and for the daptomycin-loaded scaffold group, 100% of daptomycin was cumulatively released in six days. To compare ertapenem-loaded cement and scaffold, 98% of ertapenem was cumulatively released within 10 minutes in the cement group. For the scaffold group, 100% of ertapenem was cumulatively released in 17 days. We found that the scaffold released the antibiotic more slowly and for a longer duration. Therefore, it was thought that the scaffold would be more effective on biofilm and the treatment of osteomyelitis would be more successful. Conclusions The produced scaffold was compared with cement, and it was concluded that the scaffold had better release and antimicrobial efficacy. Scaffold is more advantageous than cement because it is bioeliminable. Thus, there is no need for a second surgical intervention with the likely prevention of mortality and morbidity. Because of all these features, the scaffold seems promising in the local treatment of osteomyelitis.

Keywords: bone cement; daptomycin; ertapenem; osteomyelitis; scaffold.

Figure 1. (a) Daptomycin-loaded scaffold, (b) ertapenem-loaded scaffold, and (c) free scaffold.

Figure 2. Scanning electron microscope images: (a) ertapenem-loaded scaffold, (b) daptomycin-loaded scaffold, and (c) drug-free scaffold.

Figure 3. Effects of ertapenem and daptomycin on cell viability measured by the dimethylthiazol diphenyltetrazolium bromide assay.

Osteoblast cells were treated with ertapenem and daptomycin at various concentrations (0.01-3 mg/mL) for 48 hours. Results are represented as the mean ± standard deviation of triplicate independent experiments.

Figure 4. MTT assay for osteoblast cell proliferation on (a) polymeric scaffold, (b) cement, (c) ertapenem-loaded scaffold, (d) ertapenem-loaded cement, (e) daptomycin-loaded scaffold, and (f) daptomycin-loaded cement.

Bar express mean ± standard deviation of triplicate independent experiments.

Figure 5. Release profile of (a) daptomycin and (b) ertapenem on a polymeric scaffold.

20% (w/w) daptomycin and entarpenem were loaded onto each scaffold, and the amount of released drugs was quantified by spectrophotometry. Error bars indicate standard deviation, n = 3.

Figure 6. Comparison of the efficacies of scaffold and cement with those of antibiotic discs according to the disk diffusion method.