Assistant Professor in Residence, Preventive and Restorative Dental Sciences
D2254, 707 Parnassus Avenue
Membership effective July 2009
My current research interests are in two different, but overlapping areas: 1) Epigenetic factors, and form – function relationships; 2) Regeneration of soft-hard tissue attachment in musculoskeletal, and oral and craniofacial systems.
My current research interests as a faculty member in the Division of Biomaterials and Bioengineering, UCSF are in two different, but overlapping areas: 1) Epigenetic factors and form – function relationships; 2) Regeneration of soft-hard tissue attachment. Functional efficiency of most organs is broadly governed by two factors; genetic and epigenetic. In my laboratory we are currently studying the effect of two epigenetic factors: load and disease; and load plus disease on the bone-ligament-tooth complex using in vivo models. Furthermore, the observed load-based nanoscale events are mimicked by programming them as functional cues on synthetic substrates to promote tissue specific cell differentiation and regeneration for soft-hard tissue functional attachment. 1) Epigenetic factors influence on form-function relationship
The bone-ligament-tooth complex is an excellent bioengineered system in which several natural interfaces between soft-hard or hard-hard tissues provide biomechanical efficiency of the fibrous joint. However, functional efficiency can be impaired if any one of the interfaces and/or tissues adapt to epigenetic factors: load and disease. In both diseased and/or load-based organs, resorption or formation related biomineralization events affect the interfaces. A systematic approach to investigate mineral resorption and formation related phenomena involves harnessing principles of mechanics, materials science, and mechanobiology at organ, tissue and cell-levels in the bone-tooth fibrous joint. Models include ligature induced periodontitis to investigate bacterial induced mineral formation and resorption, and functional load modulation by food consistency and/or imposition of unidirectional vectors to investigate force (magnitude and direction of load) induced mineral formation and resorption. This excellent model i.e. the bone-ligament-tooth complex can elucidate a wide spectrum of clinical scenarios, from bony spurs related to enthesopathies to tissue regeneration related to distraction osteogenesis in both musculoskeletal, and oral and craniofacial systems. 2) Regeneration of soft-hard tissue attachment: The soft-hard tissue interfaces in the bone-ligament-tooth complex parallel several other similar interfaces in the musculoskeletal system including tendon-bone and ligament-bone interfaces. Challenges to date in oral and musculoskeletal systems include “functional regeneration” of “soft- and hard-tissue interfaces” that are seminal to the load-bearing nature of fibrous and diarthroidal joints. Parameters investigated under item 1 are programmed as “functional cues” on synthetic substrates to promote tissue regeneration/attachment specific to soft-hard tissue interfaces. Regeneration events include tissue-specific cell differentiation and basic constituents i.e. collagen, noncollagenous proteins, and apatite formation necessary to provide functional integrity for a load bearing interface.
1. Ho SP, Marshall SJ, Ryder MI, Marshall GW, The tooth attachment mechanism defined by structure, chemical composition and mechanical properties of collagen fibers in the periodontium, Biomaterials, 2007. PMID:17870156; doi:10.1016/j.biomaterials.2007.08.031
2. Ho SP, Yu B, Yun W, Marshall GW, Ryder MI, Marshall SJ, Structure, chemical composition and mechanical properties of human and rat cementum and its interface with root dentin, Acta Biomaterilia, 2009. PMID:18829402; doi:10.1016/j.actbio.2008.08.013
3. S. P. Ho, M. P. Kurylo, T. K. Fong, S. S. Lee, H. D. Wagner, M. I. Ryder, G. W. Marshall, The biomechanical characteristics of the bone-periodontal ligament-cementum complex, Biomaterials, 2010. PMID: 20541802; doi:10.1016/j.biomaterials.2010.05.024
4. J. Hurng, M. P. Kurylo, G. W. Marshall, S. M. Webb, M. I. Ryder, S. P. Ho. Discontinuities in the human bone-PDL-cementum complex. Biomaterials, 2011. PMID: 21774982; doi: 10.1016/j.biomaterials.2011.06.021
5. E. Niver, N. Leong, J. Greene, D. Curtis, M. I. Ryder, S. P. Ho. Reduced functional loads alter the physical characteristics of the bone-PDL-cementum complex. Journal of Periodontal Research, 2011, in press.