Optimize Strontium Content to Improve Bioactive Bone Cement
发布时间：2020-04-15 来源：Human Tissues and Organs Degeneration Research Center (退行性中心)
A research team led by Prof. PAN Haobo and Dr. CUI Xu from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences have developed a new strontium-substituted bioactive glass (BG) bone cement that optimizes the concentration of strontium to improve peri-implant bone formation and bone-implant contact.
The preferred treatment of large bone defects is autologous bone grafts and allografts. However, these treatments are often lengthy, arduous and associated with numerous drawbacks and complications.BG bone cement is a minimally invasive alternative to arduous and risky autologous bone grafts and allografts for the treatment of large bone defects.Previous studies from SIAT found that adding strontium (Sr) to bioactive borate glass bone cement enhanced its osteogenic capacity in vivo. However, researchers didn’t know how much Sr was needed to optimize the cement's physicochemical properties and capacity to stimulate bone regeneration. Likewise, they didn't clearly understand the molecular mechanism underlying this stimulation.Their current research answers these questions.In the present study, the scientists found that adding Sr to BGs could modulate the physicochemical properties and osteogenic activity of BG bone cements. For example, adding Sr speeded up the setting reaction of bone cements and slowed down their degradation rate.In order to determine an optimum level of Sr substitution, the researchers created bone cements composed of bioactive borosilicate glass particles substituted with varying amounts of Sr (0 mol% to12 mol% SrO) and evaluated them in vitro and in vivo.
They discovered that osteogenic characteristics were optimally enhanced with a cement (designated BG6Sr) composed of BG particles substituted with 6 mol% SrO. When implanted in rabbit femoral condyle defects, the BG6Sr cement supported better peri-implant bone formation and bone-implant contact compared to cements substituted with 0 mol%or 9 mol% SrO.
Scanning electron microscope (SEM) images of the surface morphology of BG, BG6Sr and BG12Sr cements before and after immersion of the cements in phosphate buffered saline (PBS) for 30, 60 and 90 days，the particles at the surface layer grew in size with longer immersion time and developed a more rounded morphology. (Image by SIAT)
Quantitation of the micro-CT images showed that the bone mineral density in the defects implanted with the BG6Sr (b, e) was significantly higher than that for the BG (a, d) cement and BG9Sr (c, f) cement. (Image by SIAT)
The researchers also discovered that the underlying stimulation mechanism of Sr-containing bone cements involves the activation of the Wnt/β-catenin signaling pathway in the osteogenic differentiation of human blood marrow mesenchymal stem cells (hBMSCs).These results show that BG bone cements offer a promising combination of physicochemical properties and biological performance for the minimally invasive treatment of bone defects when Sr is appropriately added.
