Preliminary Study On The Treatment Of Femoral Head Necrosis With A New Magnesium-based Hydrotalcite Material

BackgroundOsteonecrosis of the femoral head(ONFH)is a severe crippling disease.Total hip arthroplasty can only be performed to treat the collapse of the femoral head.The effective treatment for early ONFH is core decompression combined with bone grafting to delay the process of femoral head collapse as much as possible.The existing bone graft materials are challenging to meet the needs of clinical patients,so there is an urgent need for a new type of bone graft material with excellent osteogenic properties.PurposeOur group aims to synthesize a novel Mg-A1 hydrotalcite(MgAl-LDHs)nanosheet containing ytterbium(Yb),loading the anti-osteoporosis drug alendronate(AL).It can significantly promote bone regeneration in the osteonecrosis area of the femoral head.Moreover,it has injectable and X-ray imaging properties at the same time.MethodsMgAl-LDHs nanosheets were prepared by hydrothermal coprecipitation method using Mg(NO3)2·6H2O?Al(NO3)3·9H2O and Yb(NO3)3·5H2O as raw materials.AL was loaded on the surface of LDH by hydrophilic group interaction.The concentration of AL was determined by the cerium nitrate oxidation method,and the drug loading capacity(LC)and entrapment efficiency(EE)were calculated.The interaction between AL and LDH was determined by isothermal calorimetric titration.The structural characterization of LDHs and AL/LDHs was determined by high resolution scanning electron microscope(HRTEM),micro-CT,atomic force microscope(AFM),inductively coupled plasma emission spectroscopy(ICP),Fourier transforms infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),energy-dispersive X-ray spectroscopy(EDX),and dynamic light scattering(DLS).The material extracts of different concentrations of LDHs,AL/L DHs,and AL were prepared and co-cultured with MC3T3-E1 cells.CCK-8 assay and flow cytometry were conducted to verify the cytotoxicity of the materials.The osteogenic effect of the material in MC3T3-E1 cells was verified by RT-PCR,alizarin red S staining,ALP staining,and immunoblotting analysis.Moreover,the morphological changes of osteogenic differentiation were observed by fluorescein isothiocyanate(FITC)labeled phalloidin staining.The rabbit model of osteonecrosis of the femoral head was established by liquid nitrogen freezing.Furthermore,the corresponding bone graft materials were injected into the channel of LDHs group,AL/LDHs group,negative control group,and positive control group(autogenous bone transplantation),respectively.The concentrations of magnesium ion and aluminum ion in rabbit venous blood were determined by ICP-MS.The rabbit liver,kidney,and spinal cord were stained by hematoxylin-eosin to identify the biosafety in vivo.The femoral specimens were scanned by micro-CT,and the regenerated bone mass of the femoral shaft and femoral head was quantitatively analyzed.Sections of femoral specimens were stained with H&E and anti-periostin staining to detect new bone regeneration via a microscope.ResultsThe particle size of LDHs nanosheets is about 50nm,and the thickness is about 0.9nm.The EDX and XPS spectra showed that the three elements Mg,Al,and Yb,were uniformly dispersed.FT-IR confirmed that AL was successfully loaded on the surface of LDHs nanosheets,and there was no significant change for the structural characteristics of nanosheets after loading AL.When the mass ratio of AL to LDHs was 2:1,LC and EE were the largest,which were 19.7%and 98.6%,respectively.Except for the death of MC3T3-E1 cells in the AL group,the OD values of LDHs and AL/LDHs groups were positively correlated with culture time.The results of the flow cytometry of LDHs and AL/LDHs groups showed no significant difference with the blank control.There was no significant difference in the tissue structure of the liver,kidney,and spinal cord between the experimental groups and the control groups.The transcriptional and translational levels of osteogenic markers in LDHs and AL/LDHs group were significantly higher than those in the blank control group.In the animal model,the total volume of bone regeneration of the femoral shaft and bone mineral density of the femoral head in the LDHs group and AL/LDHs group were higher than those in the positive control group.ConclusionMgAlYb-LDHs nano-sheets have excellent biocompatibility,injectability,imaging property.AL can be effectively loaded on the surface of LDHs.The novel materials can effectively promote bone repair at the site of osteonecrosis of the femoral head.