Flyer

The Maurice A. Biot Endowed Lecture

Department of Civil Engineering and Engineering Mechanics

Columbia University

New York City


Functional Tissue Engineering:
The Role of Biomechanics in Cartilage Tissue Engineering

Prof. Van C. Mow

Stanley Dicker Professor of Biomedical Engineering and Orthopaedic Bioengineering
Director, Liu Ping Laboratory for Functional Tissue Engineering Research
Chair, Department of Biomedical Engineering
Columbia University


November 16, 2006 (Thursday)
2:30-3:30 pm

Inter-school Lab, CEPSR

Abstract: Articular cartilage is the load-bearing tissue within all freely moving joints of mammals, i.e., the diarthrodial joints such as hips, knees, shoulders, etc.  All diarthrodial joints must support loads of high magnitude, and function with a remarkably low coefficient friction even with the generally slow reciprocating motions.  For example, in the knee or hip, the magnitude of loading may reach higher than 15x body weight, with a normal stress up to 20 MPa acting on its articulating surfaces.  Even the shoulder, generally considered as a non-weight bearing joint, but it is actually not a non-load bearing joint.  Due to the lever law effect, there is a 20 to 1 disadvantage; thus a 10N load carried by an outstretched arm may be magnified to 200N acting across the glenohumeral joint of the shoulder.  Similarly, in the patello-femoral joint (PFJ) of the knee, again with an approximate 20 to 1 disadvantage, the force and stress levels acting across the PFJ may reach similar magnitudes.  In addition, these loads are applied, in a normal young vigorous individual, about one million times a year, with a cyclic frequency usually less than 1Hz.  For athletes, these operational mechanical requirements are increased many times.  It is no wonder that for some unlucky individuals, they develop arthritis in the hip and knee (most frequently); this is a form of failure in these natural bearings.  For any artificial material (whether it is plastic or stainless steel) used in joint prostheses to replace these failed biological bearings, prostheses failure often occur.  Tissue engineered constructs planned for replacing of damaged cartilage or resurfacing the joint surfaces have not met these demanding functional requirements; indeed, all tissue engineered cartilage have much inferior properties when compared to normal healthy cartilage, and indeed even inferior when compared with cartilage obtained from necropies of osteoarthritic joints.  Thus, there appears to be something special of natural articular cartilage that renders it to function for many decades with no signs of impairment.  What that something is has been the focus of worldwide attention for many years.

In brief, articular cartilage (and most biological tissues) is a hierarchical material with specific micro- and ultra-structural architectural feature variations that spans 8 decades of dimensional scale.  Over the years, it has been established from much basic biochemistry studies that the nano-scale structures of glycosaminoglycan and tropo-collagen molecular form at the 10-9 to 10-8m important interactions in determining the physical properties of these fundamental building blocks of the solid organic matrix of the tissue. At two orders of magnitude up, from 10-7 to 10-6m, i.e., at the ultra-scale level, the physical interactions resulting from the complex organizations of the proteoglycans and collagen network are important in determining the cohesiveness and strength of the porous-permeable matrix. At the micro- and meso- scale, 10-5 to 10-3m interactions between cells and their extracellular matrix are important in the mechano-transduction of mechanical and physical signals that modulates biosyntheses of all the constituents that comprise the tissue; these constituents form the tissues that must function within our bodies at the macro-scale, e.g., hips, knees, shoulders, etc. These elemental components form the structural anisotropies and compositional inhomogenieties that afford the tissue with a wide variety of complex mechano-electrochemical phenomena, which in turn endow this tissue not only with intriguing material properties, but also make possible their function in the strenuous mechanical environments normally found in all diarthrodial joints, as the superb bearing materials that we all know as articular cartilage.  This lecture will provide a summary of our current knowledge of some of these burgeoning fields under the rubric of biomechanics, and looks to new and challenging problems of study in functional tissue engineering  toward finding an answer(s) to the etiology of osteoarthritis and repair of damaged joint surfaces.

References
The reader may wish to consult the following texts for more information:
Brandt KD, Doherty M, Lomander LS (eds): Osteoarthritis, Oxford University Press, 2000; pp511
Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science: Biology and Biomechanics of the Musculoskeletal System, American Academy of Orthopaedic Surgeons, Rosemont, IL 2000, pp872
Guilak F, Butler DL, Goldstein SA, Mooney DJ (eds): Functional Tissue Engineering, Springer-Verlag, Inc, New York, 2003, pp426
Mow VC, Huiskes R (eds):  Basic Orthopaedic Biomechanics and Mechano-biology, 3rd Edition, Lippincott Williams & Wilkins, Philadelphia, 2005, pp720

Biographical Sketch
(source)

Mow received his BAE degree in Aeronautical Engineering in 1962 and his PhD in Applied Mechanics and Applied Mathematics in 1966 from Rensselaer Polytechnic Institute.  From 1966-1968 he was a postdoctoral fellow in Applied Mathematics at the Courant Institute of Mathematical Sciences at New York University in New York City, and from 1968-69 he was a Member of Technical Staff at the Bell Telephone Laboratories in New Jersey.  At both places he worked on mathematical theories related to ocean waves and ocean acoustics for the development of mathematical models of the sonar system used for detection of submarines along the East Coast of U.S.   In 1969, Dr. Mow joined the faculty of RPI as an Associate Professor in the Mechanics Department.

At the age of thirty, when bioengineering activities in the nation was just beginning to blossom, Dr. Mow began his bioengineering career by studying the new field of the biomechanics of soft tissues, specifically of articular cartilage.  What fascinated him was the challenge to understand how such biological materials function in the body for long periods of time and under high cyclic loads, and this became one of his career goals.  For the next seventeen years of his career as a bioengineer, along with his graduate students, he took on the challenge in a methodical way, they developrd new theories and experiments to study such biological tissues.His publications, awards and professional society leadership led him to be recognized as the Clark and Crossan Professor of Engineering at Rensselaer and the first PhD President of the Orthopaedic Research Society.

In 1986, Dr. Mow relocated to Columbia University as the Anne Y. Stein Professor of Mechanical Engineering and Orthopaedic Bioengineering, and Director of the New York Orthopaedic Hospital Research Laboratory at Columbia College of Physicians and Surgeons.  Here he developed and directed a research and teaching program in orthopaedic research comprising more than forty engineering faculty members, orthopaedic surgeons, MD and PhD fellows, graduate and undergraduate students, and other support staff members.  Today, from his research efforts, he has published over 700 papers, edited 7 books and delivered more than 475 keynote, plenary and meeting lectures world wide.

To honor Dr. Mow for his contributions to biomedical engineering, he has received numerous honors, including Fellow of ASME (1979), American Academy of Orthopedic Surgeons Kappa Delta Award (1981), ASME Melville Medal (1982), ASME HR Lissner Award (1987), Giovanni Borelli Award of the American Society of Biomechanics (1991), U.S. National Academy of Engineering (1991), Alza Distinguished Lecturer (1994), ASME RH Thurston Lectureship (1998), U.S. Institute of Medicine of the National Academy of Sciences (1998), Ray Kroc Award for Arthritis Research (twice), and Academia Sinica of Taiwan (2004).He is also the recipient of 6 honorary professorships in China and one in Hong Kong.

However, of the achievement that Van is most proud is the mentorship of his numerous Ph.D. students and postdoctoral fellows over the years.  Today, many of his students are recognized for their research contributions, and they are in leadership positions in universities and industry across the nation and around the world.  For these achievements, the American Society of Mechanical Engineers, and its Bioengineering Division have created the Van C. Mow Medal for Bioengineers, an annual award to be given to bioengineers at mid career for those who have displayed qualities of excellence in mentorship, excellence in research in biomechanics, and leadership in the profession, particularly in the Bioengineering Division of ASME.

Van C. Mow Medal: established by the ASME to honor Dr. Van C. Mow.

Questions:
E-mail: Ling@civil.columbia.edu
Tel: 212-854-1203