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Siu RK, Lu SS, Li W, Whang J, McNeill G, Zhang X, Wu BM, Turner AS, Seim HB, Hoang P, Wang JC, Gertzman AA, Ting K, Soo C. Nell-1 protein promotes bone formation in a sheep spinal fusion model. Tissue Eng Part A 2011; 17:1123-35. [PMID: 21128865 PMCID: PMC3063712 DOI: 10.1089/ten.tea.2010.0486] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 12/03/2010] [Indexed: 11/12/2022] Open
Abstract
Bone morphogenetic proteins (BMPs) are widely used as bone graft substitutes in spinal fusion, but are associated with numerous adverse effects. The growth factor Nel-like molecule-1 (Nell-1) is mechanistically distinct from BMPs and can minimize complications associated with BMP therapies. This study evaluates the efficacy of Nell-1 combined with demineralized bone matrix (DBM) as a novel bone graft material for interbody spine fusion using sheep, a phylogenetically advanced animal with biomechanical similarities to human spine. Nell-1+sheep DBM or Nell-1+heat-inactivated DBM (inDBM) (to determine the osteogenic effect of residual growth factors in DBM) were implanted in surgical sites as follows: (1) DBM only (control) (n=8); (2) DBM+0.3 mg/mL Nell-1 (n=8); (3) DBM+0.6 mg/mL Nell-1 (n=8); (4) inDBM only (control) (n=4); (5) inDBM+0.3 mg/mL Nell-1 (n=4); (6) inDBM+0.6 mg/mL Nell-1 (n=4). Fusion was assessed by computed tomography, microcomputed tomography, and histology. One hundred percent fusion was achieved by 3 months in the DBM+0.6 mg/mL Nell-1 group and by 4 months in the inDBM+0.6 mg/mL Nell-1 group; bone volume and mineral density were increased by 58% and 47%, respectively. These fusion rates are comparable to published reports on BMP-2 or autograft bone efficacy in sheep. Nell-1 is an independently potent osteogenic molecule that is efficacious and easily applied when combined with DBM.
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Affiliation(s)
- Ronald K. Siu
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Department of Bioengineering, School of Medicine, University of California, Los Angeles, California
| | - Steven S. Lu
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Department of Neonatology, Cedars-Sinai Medical Center, Los Angeles, California
| | - Weiming Li
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Department of Orthopaedics, First Clinical Hospital, Harbin Medical University, Harbin, China
| | - Julie Whang
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Section of Orthodontics, School of Dentistry, University of California, Los Angeles, California
| | - Gabriel McNeill
- Group in Biostatistics, University of California, Berkeley, California
| | - Xinli Zhang
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
| | - Benjamin M. Wu
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Department of Bioengineering, School of Medicine, University of California, Los Angeles, California
| | - A. Simon Turner
- Department of Veterinary Sciences, Colorado State University, Fort Collins, Colorado
| | - Howard B. Seim
- Department of Veterinary Sciences, Colorado State University, Fort Collins, Colorado
| | - Paul Hoang
- Section of Orthodontics, School of Dentistry, University of California, Los Angeles, California
| | - Jeffrey C. Wang
- Department of Orthopaedic Surgery, School of Medicine, University of California, Los Angeles, California
| | | | - Kang Ting
- Dental and Craniofacial Research Institute, University of California, Los Angeles, California
- Section of Orthodontics, School of Dentistry, University of California, Los Angeles, California
| | - Chia Soo
- Department of Orthopaedic Surgery, School of Medicine, University of California, Los Angeles, California
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Majumdar S, Genant HK. A review of the recent advances in magnetic resonance imaging in the assessment of osteoporosis. Osteoporos Int 1995; 5:79-92. [PMID: 7599453 DOI: 10.1007/bf01623308] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Osteoporosis is a common metabolic disorder with considerable associated morbidity and mortality. The loss of bone mineral integrity and the resultant occurrence of atraumatic fractures are typically symptomatic of the disease. Currently skeletal status is commonly assessed using non-invasive conventional radiography and scintigraphy as well as densitometric techniques such as quantitative computed tomography and dual-energy X-ray absorptiometry. But, apart from gross bone mineral density, the fine structure of trabecular bone also plays an important role in defining the biomechanical competence of the skeleton. Recently attention has been focused on deriving measures that provide information about not only trabecular bone density but also microstructure. Magnetic resonance imaging (MRI) is one such new technique which potentially may provide information pertaining to bone density and structure as well as to occult fracture detection. Cortical bone produces a signal void in MR images, due to the fact that it contains very few mobile protons that give rise to a signal in MRI; also the MR relaxation time T2 of these protons is very short which produces a very fast decay of the MR signal during image acquisition. However, the trabecular bone network affects the MR properties of bone marrow. The difference in the magnetic properties of trabecular bone and bone marrow generates local imperfections in the magnetic field. The MR signal from bone marrow is modified due to these imperfections and the MR relaxation time T2 of marrow is shortened. The extent of relaxation time shortening and hence loss of signal intensity is proportional to the density of trabecular bone and marrow interfaces and their spatial architecture. Recent investigation in this area include studies aimed at quantifying marrow relaxation times and establishing their relationship to trabecular bone density and structure. In addition, with advances in imaging software and hardware, MR images at in-plane resolutions of 78-200 microns may be obtained. The trabecular bone structure is clearly revealed in such images and studies aimed at the development of high-resolution MRI techniques combined with quantitative image analysis techniques are currently under way. These potentially useful techniques for assessing osteoporosis and predicting fracture risk are reviewed in this paper.
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Affiliation(s)
- S Majumdar
- Department of Radiology, University of California, San Francisco 94143, USA
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