Application of vancomycin-impregnated calcium sulfate hemihydrate/nano- hydroxyapatite/chitosan injectable hydrogels combined with BMSCs sheet for the treatment of infected bone defects in rabbit model

Abstract

Background Choice of bone substitutes for the therapy of infected bone defects (IBDs) attracts surgeons’ attention for years. However, single-stage bioabsorbable material that provides carriers for antibiotic releasing as well as scaffold for BMSCs sheet need further exploration. Our study was designed to investigate the effect of vancomycin-loaded calcium sulfate hemihydrate/nano-hydroxyapatite/chitosan (CSH/n-HA/CTS) hydrogels combined with BMSCs sheet as bone substitute in the treatment of IBDs. Methods The BMSCs were harvested and cultured into cell sheet. After successful establishment of animal model with chronic osteomyelitis, the 48 New Zealand white rabbits were randomly divided into 4 groups. Animals in group A were treated with thorough debridement as control. Group B were managed with BMSCs sheet. CSH/n-HA/CTS hydrogels were implanted in group C, and group D were treated with CSH/n-HA/CTS + BMSCs sheet. Gross observation and 3D reconstruction of Micro CT were performed to assess the osteogenic and infection elimination ability. Histological staining (Hematoxylin and eosin and Van Gieson) was used to observe inflammatory cell infiltration and formation of collagen fiber 4, 8 ,12 weeks after implantation. Results The bone defect of the control group was not repaired in 12 weeks as chronic osteomyelitis still existed. HE staining showed a large number of inflammatory cell infiltration around the tissue, and VG staining showed no new collagen fiber formation. In the group of BMSCs sheet, though new bone formation was observed by gross observation and Micro-CT scan, the infection was not effectively controlled due to the unfilled cavity. Some neutrophils and only a small amount of collagen fiber could be observed. Both groups of hydrogels and hydrogels/BMSCs achieved satisfactory repair effect and infection control. 3D reconstruction of Micro-CT at 4 weeks showed that the hydrogels/BMSCs sheet group had higher reconstruction efficiency and better bone modeling with normal morphology. HE staining showed little aggregation of inflammatory cells, and VG staining showed a large number of new collagen fibers. Conclusions Our preliminary results proved that compared with single material, the novel antibiotic-impregnated hydrogels acted as superior scaffold for BMSCs sheet and excellent antibiotics vector against infection, which provided a basis for applying tissue engineering technology to the treatment of chronic osteomyelitis.