Orthopaedic Research and Biotechnology Unit
A/Prof David G Little
Phone: 02 9845 3352
Fax: 02 9845 3180
See also: Orthopaedic clinics in the Hospital's Directory of Bandaged Bear Clinics and Outpatient Services.
Research Report 2008
Click here to view the our research report for 2008.
Current research program
Research / Laboratory facilities
Led by A/Prof Little, the Orthopaedic Research and Biotechnology Unit (ORB) is situated within the Research Building at The Children's Hospital at Westmead (CHW). The laboratory has sufficient space for up to 16 researchers in the wetlab area. There is also a separate post-doctoral office space for the senior research staff.
ORB has three postdoctoral researchers: Dr Schindeler, Dr McDonald, and Dr Bokko. Dr Schindeler is an expert in mouse genetic models and cell biology, and his research interests include the orthopaedic complications associated with neurofibromatosis type 1, gene therapy, and the cellular contributors to bone healing. Dr McDonald is an expert in bone histology and histomorphometry and scanning technologies. She has worked with A/Prof Little for many years examining bisphosphonates in fracture repair and the role of the osteoclast in endochondral ossification. Dr Bokko is an expert in biochemistry and molecular biology and is a recent addition to the research team.
The laboratory currently employs three research assistants for animal work, histology and cell culture. These RAs are skilled in the technical aspects of mouse surgery, cultured cell lines and primary mouse and human cells, PCR and basic molecular biology methods, calcified and decalcified bone histology, cryosectioning and immunohistochemistry, and bone scanning methods. In addition, Two PhD students and one Honours student are currently pursuing higher degrees within ORB.
Equipment includes access to central standard laboratory facilities, while the specialised equipment within or accessible to the lab include:
Cell Culture: The ORB has a dedicated Tissue Culture Suite. This suite includes Class II biosafety hoods, CO2 incubators, phase contrast microscope with digital photography capabilities, and a high speed centrifuge. Cells lines including C2C12, MC3T3-E1, HEK-293, NIH3T3 and C2H10T1/2 cells, access to sources and culturing techniques for muscle cells, calvarial osteoblasts, bone marrow osteoprogenitors/mesenchymal stem cells, RANKL-induced primary osteoclasts, and primary osteoblast-osteoclast co-cultures.
Laboratory Equipment: The laboratory has, or has same floor access to Perkin-Elmer Thermocycler (PCR machine), RotorGene 6000 (qPCR machine), Benchtop Sonicator, Beckman Coulter Avanti-JE centrifuge, SPOT/CD500 fluorescence microscopes, Confocal microscope, FACS machines (FACScalibur, FACScan), Cryostat (via Institute for Neuromuscular Research, CHW), Spectrophotometer (UV and visible spectra) & Plate reader, Film processor/developer, Bio-rad gel doc system.
Animal Facilities: Facilities at the Westmead Campus include the CHW Transgenic Facility (mice), the Westmead Small Animal Facility (mice, rats, rabbits), and the Westmead Vivarium (sheep). There is a dedicated Surgical Suite within the ORB that includes surgical operating equipment, radiological imaging equipment (see below), and an anaesthetic machine. We have developed multiple surgical models. These models include distraction osteogenesis (rabbit femur), heterotopic ossification (rat, mouse quadriceps), critical size defect (rat), and fracture repair (rat femur/tibia - closed fractures, rat femur open fracture, mouse proximal/distal tibial fractures).We have facilities for PCR genotyping of all knockout and transgenic mouse lines.
Radiological Imaging: We have licensed and experienced users in our group for X-ray (Faxitron High Resolution Digital XR Cabinet) on-site; DEXA (Piximus Small Animal DEXA Scanner) on-site; QCT (Stratec XCT Research SA pQCT Scanner) on-site; MicroCT access (Skyscan) via the University of Sydney Electron Microscopy Unit.
Other Specialized Techniques: The lab has substantial expertise in histology and histomorphometry, particularly for the examination of skeletal tissues. This includes decalcified paraffin section preparation and non-decalcified resin section preparation; standard and bone specific histological staining techniques; specialised immunohistochemical techniques; specialised histomorphometric technique using the Bioquant Nova Prime Image Analysis System (Bioquant, Nashville, USA) to generate quantitative data (on-site); and generation of high resolution imaging using the Scanscope imaging system (on campus).
Mission & Research Theme
Our mission is to advance orthopaedic care through improved understanding of bone diseases, bone healing and pharmaceutical therapies.
An emerging theme of our research is that bone healing outcomes are determined by the levels of anabolism (bone formation) and catabolism (bone resorption). In many clinical situations, our research has demonstrated that the underlying defect is excessive catabolism. This can be treated using anti-resorptive drugs, such as bisphosphonates, which are commonly used to treat osteoporosis in the aged.
In other clinical situations, we have found anabolic deficiencies that cannot be overcome by anti-resorptive drugs. In these situations, we can apply anabolic drugs, such as bone morphogenetic proteins (TGA-approved bone forming agents). However, we are increasingly finding that the effect of anabolic drugs can be maximised with co-treatment with an anti-catabolic drug. Finally, these anabolic and anti-catabolic drugs act upon stem cells found within bone and adjacent tissues. We are looking at these cells to determine their origin and whether we can increase their recruitment to enhance bone healing.
Established Research Endeavours
Bisphosphonates for fracture healing, distraction osteogenesis, and osteonecrosis
Bisphosphonates (BPs) are a class of anti-resorptive drugs that were originally developed for the treatment of osteoporosis. We speculated that the fundamental source of the pathology in some orthopaedic conditions may be due to excessive bone resorption. In these cases, BP therapies may be advantageous. Bisphosphonates are now routinely used at the Children's Hospital at Westmead to treat Perthes disease of the hip (osteonecrosis) and complications that can occur during distraction osteogenesis.
The role of osteoclasts in fracture repair
The majority of fractures heal via the process of endochondral ossification, where cartilage acts as a precursor to the primary ossification event. The cartilage is progressively removed and replaced by ossified tissue as the fracture heals. The conventional dogma purports that osteoclasts are the cells responsible for this removal of cartilage prior to bone formation. However, we have demonstrated that when we specifically inhibit osteoclasts with bisphosphonates, the early stages of fracture repair progress normally. This research has direct relevance to the clinical use of anti-resorptive drugs in fracture management.
Anabolic and anti-catabolic combination therapies
One of the main themes of our research is that bone formation can be maximised by optimising the anabolic and catabolic bone healing responses. By combining local Bone Morphogenetic Proteins (BMPs) as a potent anabolic treatment with systemic bisphosphonate therapy, we achieved a synergistic (more than additive) effect in a rat critical defect model. We are continuing to explore this drug combination in vitro and in vivo, as well as applying it to the clinical situation.
Bone defects in Neurofibromatosis type 1 (NF1)
NF1 is a common genetic disease that affects 1 in 3000 children. These children can develop severe orthopaedic problems, including scoliosis (curvature of the spine) and a tibial non-union known as congenital pseudarthrosis of the tibia or CPT. Orthopaedic surgery on NF1 children with scoliosis or a CPT has a poor prognosis. We have been using genetic mouse models of NF1 deficiency, as well as studies with NF1 patients. Our research suggests that dual problems in both bone anabolism and bone catabolism resulting from multiple cellular defects may contribute to the NF1 bone phenotype.
Emerging research directions
The role of muscle in bone repair
It is not uncommon for bone to form in abnormal locations, and muscle is the most common site for this to occur. We have speculated that muscle stem cells have a strong innate capacity to form bone, and that these cells may thus be actively recruited for bone healing. We are using a combination of cell culture and genetic mouse models to investigate the potential contribution of muscle cells to bone formation and fracture repair. This project may result in new cell-based therapies for bone repair that utilise muscle cells.
Bone tissue engineering
As an extension of our anabolic/catabolic concepts as well as muscle stem cell research, we are looking to utilise muscle stem cells, pro-anabolic drugs, and anti-catabolic therapies for bone tissue engineering. We are examining different biomaterials as drug delivery systems for various pharmaceutical agents, including polymers and ceramics. Finally, we have recently elucidated a new class of drugs that may be helpful for augmenting orthopaedic treatments. We are currently exploring the mechanism by which these drugs act in vitro, and testing their capacity to augment bone healing in vivo.
Stem cell therapies for genetic bone disease
In collaboration with a number of other groups at CHW, we are looking to adapt a selective bone marrow transplant therapy for bone disease. Severe genetic diseases such as osteogenesis imperfecta (also known as brittle bone disease) and congenital osteopetrosis are likely to benefit from an infusion of healthy cells that lack the underlying genetic deficiency, particularly when they can be enriched with gene therapy. We have recently received seed funding for a pilot project in mice.
- Ramachandran M, Ward K, Brown RR Munns CF, Cowell CT, Little DG. Intravenous bisphosphonate therapy for traumatic osteonecrosis of the femoral head in adolescents: a prospective case series. J Bone Joint Surg Am 2007;89:1727-34
First study of clinical study of outcomes of bisphosphonate treatment in osteonecrosis in adolescents.
- Little DG, Ramachandran M, Schindeler A. The anabolic and catabolic responses in bone repair: insights for biological and pharmacological intervention. J Bone Joint Surg Br 2007;89-B:425-433
Review of the anabolic catabolic paradigm for bone repair
- Little DG, McDonald MM, Bransford R, Godfrey C, Amanat M. Manipulation of the anabolic and catabolic responses with OP-1 and zoledronic acid in a rat critical defect model. J Bone Miner Res 2005;20:2044-52.
Experimental study showing synergy of anabolic and anti-catabolic treatments in bone repair
- Little DG, Peat RA, McEvoy A, Williams PR, Smith EJ, Baldock PA. Zoledronic acid treatment results in retention of femoral head structure after traumatic osteonecrosis in young Wistar rats. J Bone Miner Res. 2003;18:2016-22
First publication on bisphosphonate treatment in femoral head osteonecrosis
- Little DG, Smith NC, Williams P, Briody J, Bilston, L, Smith EJ, Gardiner EM, Cowell CT. Zoledronic acid prevents osteopenia and increases bone strength in a rabbit model of distraction osteogenesis. J Bone Miner Res. 2003;18:1300-7
Definitive publication of bisphosphonate treatment in distraction osteogenesis
- A/Prof David Little, MBBS, FRACS(Orth), FAOrthA, PhD, Unit Head
- Dr Aaron Schindeler, BSc (Hons), PhD, Research Scientist
- Dr Michelle McDonald, BMedSc, PhD, Research Officer
- Dr Paul Bokko, BSc, MSc, PhD, Research Officer
- Dr Craig Godfrey, BVSc, Veterinarian/PhD Student
- Ms Alyson Morse, BBiotech (Hons), Research Assistant
- Ms Renjing Liu, BSc (Hons), PhD Student
- Ms Nicole Yu, BE, PhD Student
- Ms Hoai-Lan Mai BSc, Technical Assistant
- Ms Tajana Lah, BBiomedSc, Honours Student
- Ms Kathy Mikulec, Technical Assistant
- Ms Lauren Stanmore, Technical Assistant
Research support (2005-2008)
|Bone Growth Foundation
||Selective cell-based therapy for Osteogenesis Imperfecta
|NHMRC Project Grant 512245
||Modelling the loss of NF1 heterozygosity in congenital pseudarthrosis of the tibia (CPT).
|AOA Research Foundation
||Manipulating the anabolic and catabolic responses for bone tissue engineering
|NHMRC Project Grant 457244
||The role of muscle cells in bone repair
|AOA Research Foundation
||Understanding the Role of Muscle Derived Cells in Fracture Repair and Heterotopic Ossification
|NHMRC Project Grant 402714
||Role of the Osteoclast in Endochondral Fracture Repair
|NHMRC Project Grant 352391
||Relationship of the anabolic and catabolic responses in healing a critical sized defect in rats
|AOA Research Foundation
||Osteopenia and bone healing in a mouse model of NF1
|NHMRC Project Grant 249400
||Effect zoledronic acid and risedronate on the preservation of the femoral head in a rat model of Perthes disease
Opportunities for Students
Postgraduate Research available at the University of Sydney.
This document was updated on Wednesday, 27 August 2008