Spring 2006 Bone Seminar Series

Schedule

February 21: Racquel LeGeros, PhD: “Calcium Phosphate-Based Biomaterials: An Update”

March 14: Christopher Price, PhD candidate: “ Genetic Variability in Skeletal Growth: How Does Biology Influence Fracture Risk?”

April 11: Jeremy Mao, DDS, PhD: "Mechanical Modulation of Craniofacial Growth"

May 9: Antonio Valdevit, MSc: “Spinal Arthroplasty”

February 21 , 2006 Bone Seminar

Speaker: Racquel LeGeros, PhD, Professor and Associate Chair, Department of Biomaterials and Biomimetics, New York University College of Dentistry

Topic: Calcium Phosphate-Based Biomaterials: An Update

Dr. LeGeros's Research Interests: Effect of carbonate, fluoride, magnesium, zinc pyrophosphate, citrate, and other elements on the formation and stability of biologic and synthetic apatites and related calcium phosphates; preparation and/or characterization of calcium phosphate–based biomaterials (bioceramics, cements, glasses, composites) for bone substitution, repair, and osteoporosis therapy; implant surface modifications and coatings

Abstract
Bone is a composite of a mineral (carbonatehydroxyapatite, CHA) and a polymer (collagen). The rationale for the use of CaP-based biomaterials is their similarity in composition to the bone mineral or bone apatite. In addition, CaP biomaterials have demonstrated bioactive, osteoconductive and sometimes even osteoinductive properties—properties that make them superior to other types of biomaterials used for similar purposes. Commercial and experimental CaP-based biomaterials are of biologic (e.g., bovine-bone-derived, coral-derived) and synthetic origin. These include: bioceramics (e.g., hydroxyapatite, HA; β-tricalcium phosphate, β-TCP; biphasic calcium phosphate, BCP, consisting of an intimate mixture of HA and β-TCP; substituted apatite—e.g., F-containing apatite, FA, and CFA), substituted β-TCP (e.g., Mg-substituted or β-TCMP), calcium phosphate cements (CPCs: calcium phosphate glasses, CPGs; CaP/polymer composites—HA/polyethylene, HA or CHA/collagen, HA or β-TCP/PLGA), coatings (plasma-sprayed, electrochemically deposited or precipitated) on orthopedic and dental implants. Applications (current and potential) of CaP-based biomaterials in dentistry and medicine include: bone repair, bone substitution, bone augmentation, as scaffolds for tissue engineering for regeneration of teeth and bones, drug delivery, gene therapy, and osteoporosis therapy. 

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March 14, 2006 Bone Seminar

Speaker: Christopher Price, PhD candidate in Biomedical Sciences, Graduate School of Biomedical Sciences; Orthopaedics Research Laboratory, Mount Sinai School of Medicine

Host: Robert J. Majeska, PhD, Associate Professor, Department of Orthopaedics, Mount Sinai School of Medicine

Topic: Genetic Variability in Skeletal Growth: How Does Biology Influence Fracture Risk?

Christopher Price’s Research Interests: Investigating the role of variability in skeletal growth and development on fracture risk; Development of novel phenotyping methods for use in skeletal health diagnosis and the genetic evaluation of fracture risk; Integrating advanced skeletal imaging techniques with novel approaches to standard bone analysis to dissect the genetic basis of skeletal disease.

Abstract
Osteoporotic fracture risk is functionally dependent on bone size and shape, and thus the processes of skeletal growth early in life and bone loss during aging. Whereas a large number of studies have focused on the role of bone loss in fracture, less is known about the role of skeletal growth and development on fracture risk. Studies have shown a strong connection between peak adult bone size and shape (i.e., robustness) and fracture risk later in life; furthermore this variability in skeletal robusticity is heritable. However, the biological mechanisms through which variability in genetics influences adult bone morphology are largely unknown. Using both engineering and biological based approaches, our lab has begun to systematically establish the functional connections between genetic background, the biological control of skeletal growth, and peak bone properties. Based on these strategies, we hope to develop new ways of identifying and predicting fracture risk early in life, and establishing novel prevention and treatment regimens. To advance this goal we are utilizing an inbred mouse model of skeletal growth and biomechanics to connect genetic variability to differences in whole bone phenotypes. In these inbred mice we have demonstrated that variability in transverse femoral growth patterns (from birth to 1 year of age) play an important role in establishing femoral robusticity. Our research demonstrated that inbred mice create very different, yet functional, adult femurs based upon genotype-specific variability in the general patterns of long bone growth (i.e., periosteal and endosteal expansion/contraction) that are common to most mammalian species (including humans). Additionally, our data suggests that variability in femoral growth patterns may be functionally coupled to genetic variability in material quality/composition. Because all genetic influences on skeletal growth are necessarily propagated through the biological influences of the osteoblast and osteoclast upon the bones surfaces we are now currently investigating the role of bone cell behavior on growth pattern variability and adult bone trait outcomes. Together, our data provide us with a systematic and hierarchical approach to begin to close the large gap between genomic variability and whole bone fracture risk.  

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April 11, 2006 Bone Seminar

Speaker: Jeremy Mao, DDS, PhD, School of Dental and Oral Surgery, Columbia University

Host: X. Edward Guo PhD, Associate Professor of Biomedical Engineering, Director of Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University

Topic: Mechanical Modulation of Craniofacial Growth

Jeremy Mao’s Research Interests: Craniofacial development, especially in response to mechanical stress; tissue engineering by stem cells and biomaterials.

Abstract
Craniofacial skeleton is load bearing, but not weight bearing. Most of craniofacial skeleton is derived from neural crest cells. The magnitude of mechanical strain that is capable of eliciting bone modeling and remodeling responses in craniofacial skeleton appears small, in comparison to appendicular bones. Isolated craniofacial osteoblasts appear to respond to the same mechanical strain differently than appendicular osteoblasts. Most craniofacial bones lengthen by bone apposition in cranial sutures, as opposed to growth plates. Sutural cells appear to readily respond to mechanical stresses. Our understanding of craniofacial skeletal development, especially in response to mechanical stress, is far from complete. Nonetheless, significant insight has been gained in the past decade towards the understanding of mechanical modulation of craniofacial growth.

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May 9 , 2006 Bone Seminar
Directions to the CUNY Graduate Center

Speaker: Antonio Valdevit, MSc, Director, Spine Research Laboratory, Lutheran Medical Center, Brooklyn, NY

Host: Peter Walker, PhD, Research Professor, New York University School of Medicine

Topic: Spinal Arthroplasty

Antonio Valdevit’s Research Interests: “My research interests include testing and evaluation of spinal devices both in the fusion and arthroplasty field. In addition I have begun to explore methods to improve upon the designs of bioreactors currently in use. I feel as though significant advancements could be made if a more mechanically controlled environment could be created in conjunction with the biological surroundings.”

Abstract
This presentation will cover the basic elements associated with spinal biomechanics and provide a classification based on the mechanical characteristics of devices under development. In addition, the mechanical requirements for these devices along with test data will be shown. Finally, a study elucidating the stability requirements for intervertebral devices in general will be presented.

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