Heparanase Expression In Necrosis Bone And Plasma Of The Osteonecrosis Of The Femoral Head

Objective: Osteonecrosis of femoral head（ONFH） is a relativelycommon disease with devastating clinical entity characterized primarily bymedulla ossium ischemia, resulting in articular surface collapse andeventual joint function disturbance【1】. The etiologies could be divided intotwo categories of traumatic and non-traumatic, the former one mainlycaused by fracture and dislocation that leads to bone cell ischemia andhypoxia【2】, another one etiology is application of corticosteroid, alcoholabuse and idiopathic【3-5】. Large dose corticosteroid intake increases bloodviscosity and cholesterol significantly, causes microthrombus formation,microcirculation disturbance within bone marrow, then followed femoralhead hypoxia, edema, intraosseous pressure raising, resulting in ONFH【6】.Alcohol abuse induces bone marrow mesenchymal stem cells differentiateinto adipocyte, reduces osteoblast, adipose tissue accumulated,intraosseous hypertension, in the end ischemia and osteonecrosis occurred【7】. Idiopathic ONFH without obvious causes makes up15％-20％ofnon-trauma ONFH, the pathogens relate with fat embolism andmicrothrombus【8】.In the physiopathologic mechanism of non-traumaONFH, fat embolism, intravascular coagulation and osteonecrosis coexisttogether, some researchers put out a conclusion that intravascularcoagulation is a common pathway leading to ONFH, which could beactivated by several potential causes such as intraosseous fat embolism,endotoxin, anaphylaxis reaction, et al【9】.Heparanase is an endo-β-D-glucuronidase, which degrades heparansulfate side chains of heparan sulfate proteoglycans (HSPGs) in theextracellular matrix(ECM). Heparanase plays an important role in ECM degradation, facilitating the migration and extravasation of tumor cells andinflammatory leukocytes【10-11】. Heparanase is a strong proangiogenic【12】andprothrombotic【13】factor involved in wound healing process. Heparanasewas shown to up regulate TFPI and TF expressions【14】following release ofTFPI from the endothelial cell surface, resulting in increasing endothelialcell surface coagulation【15】. Heparanase increases the generation ofactivated factor Xa in the presence of tissue factor, thus activatescoagulation system【13】.Patients with idiopathic ONFH are in the state of hypercoagulability.Heparanase could activate coagulation system, and facilitates themigration and extravasation of tumor cells and inflammatory leukocyte,it’s meaningful to research on the expression levels of heparanase andillustrate mechanism of hypercoagulability. In previous publications,heparin could attenuate empty osteocytic lacunae in femur head inosteonecrosis【17-19】, the mechanism still keeps unknown. Heparanase isstrongly inhibited by heparins which keeps in balance in the body. Ourstudy aims to explore the level of heparanase and TFPI in plasma andnecrosis bone of idiopathic ONFH patients, and to illustrate molecularmechanism of heparins in curing and preventing ONFH.Methods:32hospitalized patients with unilateral idiopathic ONFHfrom2012.6-2013.1, including22males and10females with mean age of53.6(range33-65year-old). Inclusive criteria: without nephrosis,hypertension, tumor,acute or chronic inflammation, without drugsinfluenced on systemic coagulation. The patients were divided into Ⅰ-Ⅳgroup based on ARCO staging system of imaging examination includingX-ray, CT scan, MRI, each group8patients.8patients(5males and3females,average57.1,range53-65year-old) with femur neck fractureunderwent hip arthroplasty within72hours after injury, in accordance withthe inclusive criteria,regarded as control group. The patients in ARCOⅠstage underwent core decompression. These in ARCOⅡ group haddebridement and cancellous iliac grafting.6patients in ARCO Ⅲ had total hip arthroplasty,1of the group had debridement and cancellous iliacgrafting, another one had core decompression and allo-fibular grafting.The ARCOⅣ stage group and control group had total hip arthroplasty. Hpaand TFPI level in plasma were tested by ELISA from venous bloodsamples extracted from median cubital vein pre-operation. In Operation,incise necrosis bone in subchondral and weight-bearing region fromcontrol and ARCOⅡ-Ⅳ group, one part preserved in liquid nitrogen forwestern bolt analysis, another part was fixed with10%paraformaldehydefor pathological examination.Result: Heparanase and TFPI level are high in plasma in patientswith ONFH pre-operation than control group, the level increase graduallyin ARCOⅠ-Ⅲ stage, and decrease in ARCO Ⅳ group with significantdifference. Protein levels in necrosis bone were up-regulated expressedthan control group. The expression trend was up-regulated in ARCOⅡ-Ⅲstage, the level in ARCO Ⅲ stage was high than in ARCO Ⅱstage withsignificant difference. The levels in plasma and necrosis bone has somecorrelation.In femroal head necrosis bone,medullary cavity, fat cellsdiameter increase, fat tissue accumulates, the trabecular bone is thinning,fracture, bone fragments occured, empty osteocytic lacunae increasedobviously. As necrosis worsen, the fat cells integrated into the bubble,hematopoietic tissue in the bone marrow decreased significantly, thetrabecular bone structure disorder, became fracture, sparse, slender, emptyosteocytic lacunae increased.Conclusion:1、Heparanase and TFPI expressions upregulate with necrosis degreeaggravating before femoral head collapsed, play an important role in theprocess of ONFH.2、Heparanase keeps dynamic balance with heparins in body fluid, andelucidate mechanisms of heparins in treating and preventing ONFH. 3、Heparanase could be a hemodynamic parameter and new target of drugtreatment of patients with ONFH.