Archives—March 2010

The role of environmental factors in regulating chondrogenesis of mesenchymal stem cells – Implications for cell based cartilage repair therapies

Thursday March 25, 2010 4:00 – 5:00 p.m.
ME-EM Building, Room 112

Daniel Kelly
University of Dublin, Trinity College

Articular cartilage has a limited capacity for repair. Cell based therapies such asAutologous Chondrocyte Implantation (ACT) can be used to treat cartilage defects, butthere is no conclusive evidence that conventional AC! is more effective thanestablished techniques such as microfracture. This has lead to increased interest innovel tissue engineering strategies and alternatives to chondrocytes such asmesenchymal stem cells (MSC5) for cell-based cartilage repair therapies. Central tothe success of any cell-based therapy is a fundamental understanding of how the localmicroenvironment influences cell phenotype and subsequent matrix synthesis andorganisation. This seminar will first review how our lab is using in vitro models tosystematically investigate how MSCs respond to their biophysical and biochemicalenvironment. Key aspects of the in vivo joint environment, such as oxygen tensionand dynamic compression, will be considered. The seminar will then outline how theinformation provided by such experiments can be used to develop models of cellbehaviour, which can be combined with tools such as the finite element method todevelop predictive tools that can potentially be used to improve outcomes in tissueengineering and regenerative medicine.

Characterization of Poroelastic Properties of Hydrated Tissues by Indentation Testing

Thursday March 18, 2010 3:00 – 4:00 p.m.
ME-EM Building, Room 112

Michelle L. Oyen
Cambridge University

It has been established that changes in the mechanical properties of tissues are associatedwith disease state, due to altered structure-properties relationships at the level of tissuemicrostructure. Further, it has been shown that the time-dependent response of tissues ismore sensitive than the elastic response to some changes in connective tissues. As such,there is a clear need for the development of characterization techniques that allow for themeasurement of multiple facets of material behavior. Bone and other hydratedbiological tissues are characterized as poroelastic: the mechanical response can bedescribed with a continuum two-phase model that incorporates fluid flow through aporous elastic solid. Although poroelasticity has been studied for many decades, thecoupled nature of poroelastic constitutive equations results in a problem that is typicallysolved only with numerical or computational models. Thus, poroelastic analyses have notbeen popular for routine data analysis. In the past decade, however, automatednanoindentation testing has allowed for the generation of large volumes of mechanicaldata, and the need for high-throughput data analysis for time-dependent materials hasbeen established. In the current study, a new method is developed for high- throughputdata analysis based on a master library of indentation creep curves for sphericalindentation of a poroelastic material. Indentation tests are compared for hydrated equinebone samples tested at two disparate length-scales, encompassing both nanoindentationand microindentation instruments, and demonstrating two distinct families of controllingporosity within the same physical sample. Consistent with prior pilot studies on bonenanoindentation, the hydraulic permeability obtained from nanoindentation tests issignificantly smaller than that found from microindentation tests and yet the elasticmodulus values obtained from the two sets of tests do not differ. The same framework isused in characterizing compliant gels with significantly smaller stiffnesses and greaterpermeabilities than bone because the approach is based on master curves, materialswith any values of mechanical properties can be studied within the same frameworkwithout the need to run material-specific simulations. This study demonstrates thepotential for gaining greater understanding of mechanical responses in hydrated materialswhile remaining in a simple experimental indentation testing framework conducive tohigh-throughput materials characterization.

Jeffrey Naber Receives 2010 SAE Forest R. McFarland Award

Associate Professor Jeffrey Naber has been selected to receive the 2010 SAE Forest R. McFarland Award.

This award recognizes individuals for their outstanding contributions toward the work of the SAE Engineering Meetings Board (EMB) in the planning, development, and dissemination of technical information through technical meetings, conferences, and professional development programs or outstanding contributions to the EMB operations in facilitating or enhancing the interchanges of technical information.

The Award was established in 1979, this award is administered by the EMB and honors the late Forest R. McFarland who was himself an outstanding session organizer, a chairman of the Passenger Car Activity and a member of the EMB. Funding for this award is through a bequest by Mr. McFarland to SAE and consists of a framed certificate presented at the SAE World Congress.

Nanomechanical microcantilever sensor: a versatile platform for physical, chemical, and biological detection and analysis

Thursday March 4, 2010 3:00 – 4:00 p.m.
ME-EM Building, Room 112

Seonghwan Kim
Oak Ridge National Laboratory

Microcantilevers have been used for atomic force microscope (AFM) anddiverse microelectromechanical systems (MEMS), including sensors andactuators, for over two decades and have been exploited as mechanicaltransducers for physical, chemical, and biological sensing applications. Thedynamic frequency response and the static nanomechanical deflection of amicrocantilever are two main transduction mechanisms for microcantileversensors. Therefore, systematic characterization of dynamic and staticresponses of microcantilevers is essential for microcantilever sensordevelopment. In this talk, I will briefly review the history of themicrocantilever sensor development and discuss my fundamental study for thedynamic and static responses of microcantilevers. After this, threerepresentative microcantilever sensor applications for physical, chemical, andbiological detection and analysis will be presented and the future directionwill be discussed.

Alexandru Herescu Selected to Receive a 2010 DeVlieg Foundation Fellowship

Alexandru Herescu, Graduate student in Mechanical Engineering, has been selected for a 2010 DeVlieg Foundation Fellowship.

The Graduate School Review Panel recommended Alexandru Herescu’s application for the DeVlieg Foundation Fellowship and the Dean of the College of Engineering concurred. Competition for these Fellowships is vigorous and the panel was impressed with Alexandru’s research, publication record, and contribution to the mission of Michigan Tech.

Charles DeVlieg, founder of the DeVlieg Machine company of Royal Oak, Michigan started the foundation in 1961 to help aid and promote students in focus areas such as; engineering, wildlife research and natural resource conservation. The foundation was later taken over by Bud DeVlieg (Charles’ son), and later again by Kathryn DeVlieg (Bud’s wife) all who have since deceased. Today, the board of directors is run by Bud’s daughters, Janet DeVlieg Pope and Julia DeVlieg, along with five additional board members and Curt Deroo, their legal counsel and financial executive. The funding for the foundation had begun by personal contributions.