The Experimental Research Of Bone Marrow Mesenchymal Stem Cells Combined With NHAC/PLA In The Treatment Of Avascular Necrosis Of Femoral Head

BackgroundAvascular necrosis of the femoral head(ANFH)is a very common orthopaedic disease,which is caused by many factors,such as long-term heavy drinking,long-term high-dose glucocorticoid use,traffic accidents,accidents and falls of the elderly[1-3].The clinical manifestation is that the patient's lower limbs are painful and limited in activity,which seriously affects the study,work and life of the patient,causes great physical and mental harm to the patient,and causes serious economic burden to the society and family.In China,8.12 million people aged 15 and over suffer from non-traumatic ANFH,and various injuries further increase the incidence of ANFH[4].Most scholars believe that tissue edema and intramedullary hypertension caused by long-term continuous ischemia and hypoxia in femoral head necrosis make it very difficult for tissue regeneration and repair[5],thus leading to continuous and irreversible disease progression[6]Previous experimental and clinical studies have shown that appropriate core decompression is effective for the treatment of ANFH[7,8].It is considered to be a classic method for the treatment of femoral head necrosis in addition to total hip arthroplasty(THA)and simple femoral head replacement.However,with the further development of experimental and clinical studies,the research results of some scholars have confirmed that the effect of simple CD on ANFH is not very satisfactory[9],most patients don't really reverse ANFH,still not avoid the second artificial joint replacement to completely remove the pain back to normal life.Bone marrow mesenchymal stem cells(BMSCs)are an ideal candidate for tissue-engineered bone(TEB),because BMSCs are easily isolated and cultured and have rich differentiation potential[10-12],especially toward the direction of cartilage and bone differentiation.Previous studies have shown that scaffold materials with 3D micropore structures can promote the growth of neovascularization and induce BMSCs differentiation to enhance osteogenesis at the bone defect site in vivo[13,14].A 3D porous biomimetic scaffold,nano-hydroxyapatite/collagen I/poly-L-lactic acid(nHAC/PLA),with properties similar to natural bone,as an excellent bone replacement graft,more and more attention has been paid to it[15-17].Our previous studies have also confirmed that nHAC/PLA have good biocompatibility,bone conductivity and biodegradability in repairing long bone defects in rats,and have obvious promoting effect on osteogenesis at fracture sites,which can accelerate fracture healing[18].In this study,TEB was constructed by BMSCs combined with nHAC/PLA in vitro and implanted into the bone tunnel after CD of the necrotic femoral head.Its role in promoting tissue regeneration and repair of femoral head necrosis area was detected by imaging and histology,which provided a new treatment idea and method for ANFH.ObjectiveTo explore the method of constructing TEB by combining BMSCs with nHAC/PLA scaffolds in vitro,improve CD experimental approach of the rabbit ANFH model,and observe the effect of CD combined with TEB implantation on tissue regeneration and repair of the femoral head necrotic area.MethodsBMSCs were implanted on the surface and inside of nHAC/PLA by multi-point layered injection of fine needles,and the TEB was constructed in a strictly sterile environment in vitro.Scanning electron microscopy(SEM)and hematoxylin and eosin(HE)staining were used to observe the adhesive condition of cells on the surface and inside of the scaffold.30 New Zealand rabbits to establish ANFH models by lipopolysaccharide(LPS)ear vein injections combined with large dose methylprednisolone(MPSL)gluteal muscle injections.At 6 weeks after the last injection of MPSL,magnetic resonance imaging(MRI)and HE staining confirmed the successful establishment of the ANFN models.24 ANFH models were randomly divided into 3 groups:group A(n=8),pure CD;group B(n=8),CD+nHAC/PLA;and group C(n=8),CD+BMSCs-nHAC/PLA.All animal models were anesthetized by intravenous injection of 3%sodium pentobarbital(1ml/kg).CD was performed under the posterolateral cartilage of the femoral head without X-ray guidance,then nHAC/PLA or BMSCs-nHAC/PLA scaffolds were implanted into the bone tunnel.At 4 weeks after operation,osteogenesis and stent degradation in decompression tunnel were observed by CT and micro-CT.Newly bone-like tissue and angiogenesis in decompression tunnel and stent were observed by HE staining.ResultsAfter BMSCs were implanted into nHAC/PLA scaffolds for 24 h,HE staining and SEM showed that the cells were evenly distributed inside and outside the scaffolds.4 weeks after operation,HE staining and CT showed that capillaries and newly bone-like tissues in group C were more than those in group B and group A,and micro-CT showed that the coverage rate of new bone and the degradation degree of implant materials in group C were higher than those in group B.ConclusionsTEB can be constructed quickly by fine needle multi-point stratified injection method.The posterolateral subchondral approach of the femoral head can quickly and accurately complete CD opration and TEB implantation without X-ray guidance.BMSCs-nHAC/PLA is conducive to early regeneration and repair of ANFH after CD surgery,and improves the efficacy of CD surgery for ANFH.It is a new strategy for the treatment of ANFH.