In vivo evaluation of the subchronic systemic toxicity of akermanite bioceramic for bone regeneration following ISO standard methods

Although the akermanite (Ca2MgSi2O7) bioceramic has been confirmed to possess favorable osteogenic activity, until now little was known about its in vivo subchronic systemic toxicity, which is important for determining the biocompatibility and the clinical applications of the material in bone implants. In this study, the subchronic systemic toxicity of akermanite bioceramic was for the first time investigated according to well-accepted ISO standard methods. Following the method, healthy adult Wistar rats were injected with certain amounts of extracts of akermanite bioceramic that was intended to simulate the ionic product during the degradation of the material when implanted into the body. At day 28 after injection, the general body conditions, blood cytology, blood biochemistry and histology of all important organs of the rats were examined. The results showed that there was no significant difference in the hemoglobin concentration, red blood cell count, platelet count and white blood cell count between the rats with injection of akermanite bioceramic extracts and the saline control. The indicators of liver function, including aspartate aminotransferase and alkaline phosphatase, and kidney function, including blood urea nitrogen and creatinine, did not show significant difference between the two groups (P > 0.05). In addition, the results of histological examination showed that the extract of akermanite bioceramic did not cause any pathological changes to important organs such as the heart, liver and kidneys. These findings demonstrated that the ionic product derived from the degradation of akermanite bioceramic did not cause in vivo subchronic systemic toxicity. The results of the current study provided more strengthened evidence for the biosafety of akermanite bioceramic and suggest that this material with desirable biocompatibility may be a potential candidate for orthopedic clinical applications.