Transcription Factor Runx2 in Necrotic Femoral Head Tissue
Condition: Osteonecrosis of Femoral Head
MeSH terms: Osteonecrosis
Study type: Observational

Summary: 
      The trial detected mRNA expression of several bone repair-related genes, including Runx2, in
      the femoral head and neck of patients with osteonecrosis of femoral head (ONFH) . Runx2
      expression was compared with that of identical tissue from osteoarthritis patients to
      identify expression in necrotic femoral head tissue, which will help clarify the role and
      possible clinical significance of Runx2 in femoral head necrosis, bone repair and
      reconstruction.
    

Detailed description: 
      Osteonecrosis of the femoral head (ONFH) is a destructive degenerative disease that can
      develop into subchondral and articular facet cartilage collapse. Among proposed pathological
      mechanisms underlying ONFH, much attention has been paid to the theory of increased
      intraosseous pressure. The core of this theory is an unbalance in osteoblast and adipocyte
      differentiation of bone marrow mesenchymal stem cells (BM-MSCs). The occurrence and
      development of osteonecrosis has been related to abnormal metabolism and differentiation of
      BM-MSCs. Normal adult BM-MSCs can differentiate into adipocytes and osteoblasts to maintain
      normal physical status. In response to exogenous stimuli (for example, use of exogenous
      hormones or alcohol), the bone marrow microenvironment changes to allow more BM-MSCs to
      differentiate into adipocytes, leading to increased bone marrow cavity pressure, thereby
      inducing ischemic ONFH.

      Overexpression of Runx2, an osteoblast-specific transcription factor, can increase osteoblast
      differentiation of BM-MSCs, thereby strengthening the effects of BM-MSC transplantation to
      repair bone defects and necrosis. By controlling expression of osteocalcin, an
      osteoblast-specific gene, Runx2 also controls osteoblast differentiation and functioning.
      Osteocalcin, a common indicator used to evaluate bone formation and conversion rate, is a
      bone metabolism-regulating factor generated and secreted by osteoblasts; thus, it is
      considered to be a good marker for bone functioning. In a previous study by Chen et al.,
      seven patients with glucocorticoid-induced ONFH at Association Research Circulation Osseous
      (ARCO) Stage IV were included as an experimental group and seven patients with femoral neck
      fracture served as a control group. Immunohistochemical staining and quantitative polymerase
      chain reaction (PCR) were used to detect osteocalcin immunoreactivity and Runx2 expression in
      femoral head and neck tissue. They found that glucocorticoid-induced ONFH is likely closely
      related to osteocalcin.

      ONFH results from an interruption of the blood supply to the femoral head or injury-caused
      death of chondrocytes and bone marrow components. During subsequent repair processes, bone
      morphogenetic proteins (BMPs) not only stimulate BM-MSCs to differentiate into osteoblasts,
      but also promote osteoblast growth; BMP-2 is the key factor regulating bone tissue formation.

      Sclerotin loss after ONFH is closely related to an unbalance in osteoclast activity and
      differentiation. Osteoprotegerin can inhibit bone absorption of mature osteoblasts and induce
      apoptosis of osteoblasts. Osteoprotegerin and its ligand system have been confirmed as key
      factors regulating osteoblast formation and differentiation, while bone absorption plays an
      important role in the pathogenesis and treatment of osteoporosis, osteoarthritis and bone
      tumors.

      To the best of our knowledge, there have been no controlled clinical trials examining BMP,
      osteocalcin, osteoprotegerin or, in particular, Runx2 messenger RNA (mRNA) expression in
      femoral head tissue of patients with ONFH at Ficat Stage III-IV and osteoarthritis. In this
      non-randomized, parallel-controlled trial, we will use real-time PCR (RT-PCR) to detect
      Runx2, BMP-2, BMP-7 and osteoprotegerin mRNA expression in femoral head tissue from patients
      with ONFH at Ficat Stage III-IV. Simultaneously, we will detect osteocalcin immunoreactivity
      using an immunohistochemical staining method, and compare with osteoarthritis patients for
      the purpose of clarifying mechanisms of these factors in bone reconstruction post-ONFH.

      Data collection, management, analysis and open access Data collection: According to the trial
      design, a table will be formulated for data collection. Collected data will be input into an
      electronic database by professional staff using a double-data entry strategy.

      Data management: Information accuracy will be checked when all recruited patients are
      followed up. The database will be locked by the researcher in charge and will not be altered.
      All information relating to this trial will be preserved by Shengjing Hospital of China
      Medical University, China.

      Data analysis: The electronic database will be fully disclosed to a professional statistician
      for statistical analysis.

      Data open access: Published data will be available at www.figshare.com. Statistical analysis
      Statistical analysis will be performed by a professional statistician (blinded to grouping)
      using SPSS 19.0 software. If Runx2, BMP-2, BMP-7 and osteoprotegerin mRNA expression, as well
      as osteocalcin immunoreactivity in the femoral head and neck of patients with ONFH and
      osteoarthritis, are normally distributed, a two-sample t-test will be used to compare
      differences between groups. If, however, these data are not normally distributed, a
      Mann-Whitney U test will be used. A level of P < 0.05 will be considered statistically
      significant.
    

Intervention name(s): osteonecrosis of femoral head group; osteoarthritis group
Intervention type(s): Procedure; Procedure
Intervention description(s): The patients with osteonecrosis of femoral head will undergo total hip replacement.; The patients with osteoarthritis will undergo total hip replacement.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Fifteen patients with ONFH at Ficat Stage III¬-IV and 15 patients with osteoarthritis will
        undergo total hip replacement. Femoral head specimens will be collected and ex vivo
        specimens numbered. Using RT-PCR, Runx2, BMP-2, BMP-7 and osteoprotegerin, mRNA expression
        levels will be quantitatively analyzed. Osteocalcin immunoreactivity will be detected using
        immunohistochemical staining. Professional staff, blinded to grouping, will perform outcome
        index detection and statistical analysis.