Newsletter of the Institute for Biomedical Engineering

University of California, San Diego May 1999 Vol. 6, No. 1

Message from the Director

I am pleased to write this message on behalf of the Institute for Biomedical Engineering (IBME) and the Department of Bioengineering. We are at an exciting time witnessing many important progresses. The planning of the new Bioengineering Building, to be named Powell-Focht Building, is moving forward smoothly (p. 2). A ground-breaking ceremony will take place on August 12, 1999 on the Pryatel Field and Warren Mall. UCSD has approved the naming of our Institute as the Whitaker Institute for Biomedical Engineering, and this will be submitted to the Whitaker Foundation for approval by its Governing Committee (p. 3). The national ranking of UCSD in Biomedical engineering, as reported by the U.S. News and World Report, is rising again to number two (p. 5). Our faculty and students gained new awards and honors (pp. 11, 12). The 1999 Bioengineering Graduate Research Symposium, organized by the Bioengineering Graduate Students Group, was a great success (p. 2). Eight doctoral students completed their Ph.D. studies and will receive their degrees in June (p. 12). Seventeen new Ph.D. students will enter the UCSD Bioengineering program in Fall 1999 (p. 8).

At the Jacobs School of Engineering Third Annual Recognition Banquet held on May 7, 1999 (p. 4), the Whitaker Foundation and the Powell Foundation were presented with the Philanthropy Awards for their outstanding contributions and generous gifts. Erik T. Engelson, M.S., Bioengineering, 1984, received an Outstanding Alumnus Award for his innovative device for stroke prevention. We express our warmest congratulations and sincere thanks.

We mourn the passing of Mr. Herbert Kunzel, Past Chairman of the Board of the Powell Foundation, who was a great friend and generous benefactor (p. 3). We celebrate his rich life and his impact in enriching the lives of others.

Our Industrial Affiliates continue to provide important support to our education and research programs. We are pleased to feature Trega Biosciences, Inc., in the Profile of IBME Industrial Affiliates in this issue of the Newsletter (p. 6). Dr. Robert Sah, who has done a marvelous job in editing the Newsletters in addition to his superb achievements in research and education, is featured in this issueís Faculty Profile (p. 9).

Professor Sheldon Weinbaum delivered the Richard Skalak Memorial Lecture on May 20, 1999, and the Distinguished Alumni Award Lecture will be given by Professor Schmid-Schönbein on June 11, 1999 (p. 11).

As the Spring Quarter is about to end, I would like to wish everyone a happy summer.


Construction of the Powell-Focht Bioengineering Building Is Moving Forward

The Whitaker Foundation Leadership Award of $18 million (see news on IBMS Naming), the Powell Foundation gift of $8 million (see Memoriam on Mr. Herbert Kunzel), and other matching funds from university and other sources have made possible the construction of a new Bioengineering building with a total space of 105,000 gross square feet or 63,000 assignable square feet. The building will be named the Powell-Focht Bioengineering Building, in honor of the Powell Foundation and its late Chairman of the Board Judge James L. Focht.

Shortly after the granting of the Whitaker Foundation Leadership Award, the University appointed a Building Advisory Committee and made an announcement to invite applications from architectural firms to be the executive architect of this new building. Close to thirty firms submitted their proposals, and most of them are excellent. After rigorous review by the Architect Selection Committee and the Bioengineering faculty, Anshen and Allen in Los Angeles was chosen as the Executive Architect on March 3, 1999. On March 24, Research Facilities Design in San Diego was selected as the Laboratory Consultant. Bioengineering faculty, students and staff, together with faculty, staff, and administrative members in other units on campus, have formed eight subcommittees for the planning of the new building. Representatives from the two firms have met frequently with these subcommittees and the Building Advisory Committee, and they will soon begin to make preliminary drawings. The University will hold a Ground-breaking Ceremony on the Warren Mall on Thursday, August 12, 1999, in the afternoon. Further information will be announced when it becomes available. Please mark your calendar and join us for this joyous occasion.


1999 Bioengineering Graduate Research Symposium

The Bioengineering Graduate Students Group (BEGS) held the 1999 Bioengineering Graduate Research Symposium on March 6, 1999, at the UCSD Engineering campus. This marks the 13th year which BEGS has organized the research conference allowing the graduate students to present their continuing research to the local bioengineering community. The symposium consisted of overview talks from each laboratory as well as podium presentation from individual student researchers followed by a happy hour reception and poster presentations in the early evening. An abstract book was published containing summaries of the overviews from each laboratory and research from all the student contributors. For those who could not attend and are interested in exploring the innovative research presented at the symposium, additional copies of the abstract book are available through Elizabeth Hickman, Industrial Relations (822-2290, e-mail: mehickman@ucsd.edu ). BEGS would like to thank the UCSD Graduate Student Association, the Office of Graduate Studies and Research, the UCSD Department of Bioengineering and the Industrial Affiliates Program for funding the event.

ó Roland Kaunas, Chair, Organizing Committee of BEGS


IBME Visiting Scientists

Dr. Oliver Stack, Applied Cell Biophysics and Bioengineering, Aachen University of Applied Sciences, Germany, is working with Dr. Geert Schmid-Schönbein and Dr. Shunichi Usami of the Department of Bioengineering from July to October 1999.

Dr. Jan Fridén, Professor of Hand Surgery from Göteborg University, Sweden is visiting Dr. Richard Lieberís laboratory on sabbatical this year and has just dedicated a new laboratory dedicated to muscle studies in hand surgery. Dr. Fridén can be reached at (619) 552-8585, extension 7016.

Andreas Steingoetter, from Karlsruhe, Germany is doing his Diplomarbeit studies in the Department of Bioengineering.


Herbert Kunzel (1909-1999)

Mr. Herbert Kunzel, Chairman of the Board of the Powell Foundation, died on April 17, 1999 at the age of 90.

Mr. Kunzel had many outstanding accomplishments in his life. From 1935 to 1953, Mr. Kunzel was a trial and corporate attorney in San Diego. He later worked for the legal department of Solar Turbines, and within 10 years was named the companyís president in 1956. He is credited with increasing Solarís base beyond military contracts. Mr. Kunzel served on the Powell Foundation Board from 1969 to the time of his death, and was the chairman and executive director of the Board since 1986. In addition to his work with the Powell Foundation, he was also involved in civic organizations included the San Diego Chamber of Commerce, the United Way, the Red Cross, the Navy League and the Rotary. He also served on the board of Scripps Clinic and Research Foundation. Mr. Kunzel was a tremendous friend and supporter of UC San Diego and the Jacobs School of Engineering.

UCSD Bioengineering was very fortunate to receive the most generous gift from the Powell Foundation due to Mr. Kunzelís confidence in our program. Through Dean Connís effort, UCSD had asked for a gift in the amount of $3 million for the construction of the new Bioengineering building, which was approved by the Foundation in 1997. In April 1998, shortly after the release of the high ranking of our program in the U.S. News and World Report, Mr. Kunzel called Dean Conn to increase the gift from $3 million to $8 million. We deeply appreciate this generosity beyond description. This kind of gift without being asked is the most precious of all. The monetary value is tremendous, but the manner it came about was even more precious. It represented a deep personal trust. This human aspect of the gift will be long remembered more than anything else, even beyond the life of the building that the gift has made possible for its construction. Nothing means more than this. We will do our very best in making sure that the Powell-Focht Building will be the best bioengineering building any where and that the work done in the building will realize our goal of implementing outstanding research and educational programs to improve the health and well-being of humankind. Mr. Kunzel made lasting contributions in many ways. While we mourn his passing, we celebrate his rich and wonderful life. The world has been fortunate to have, Mr. Kunzel who made life better for others. We are fortunate to have known him and to be his "chosen people." Mr. Kunzel is survived by his wife Minerva who worked closely with him on his philanthropic endeavors; four children, Ridge of San Diego, Charles of Santa Barbara, Kurt of San Francisco and Daphne Sheffield of Santa Ana; and eight grandchildren. All of us in UCSD Bioengineering wish to express our most sincere condolence and gratitude.


IBME Will Be Named Whitaker Institute for Biomedical Engineering

The Leadership Award granted by the Whitaker Foundation has made the construction of the new Bioengineering building possible. The Foundation conducted a thorough and rigorous two-stage evaluation, which consisted of a review of the written proposal and a site visit on September 23-24, 1998 at UCSD. The results of the reviews were so positive that we were allowed to make a supplemental request of $4.2 million in addition to the initial request of $13.8 million, bringing the total amount to $18 million. This was approved by the Governing Committee of the Foundation in October 1998, and the funding of the Award began in November 1998. Of the many applications, the Whitaker Foundation approved only two Leadership Awards for the first round of funding of this new Award; the other institution who received the award is Johns Hopkins University. In recognition of the tremendous contribution and impact by the Whitaker Foundation on Bioengineering not only at UCSD, but also throughout the nation, members of the IBME voted unanimously to name our Institute the Whitaker Institute for Biomedical Engineering. This proposal has been formally approved by the University and will be forwarded to the Whitaker Foundation Governing Committee for final approval. This naming of the Institute will be an important part of the Ground-breaking Ceremony for the new building to be held on August 12, 1999.


The Irwin and Joan Jacobs School of Engineering Third Annual Recognition Banquet

On May 7, 1999, the Irwin and Joan Jacobs School of Engineering co-hosted the Third Annual Recognition Banquet with Solar Turbines Incorporated and QUALCOMM Incorporated. 37 companies sponsored this years banquet and 420 guest attended the banquet. Included in the Banquets list of awards were the Philanthropy Award and the Outstanding Alumnus Award. Two well deserving Foundations received this yearís Philanthropy Award, The Charles Lee Powell Foundation and The Whitaker Foundation. The Charles Lee Powell Foundation is dedicated to the advancement of science and engineering research and excellence in teaching. The Foundation was formed from the estate of Charles Lee Powell, a distinguished Los Angeles civil engineer specializing in concrete underground structures. The Powell Foundation has offered invaluable contributions to the Jacobs School, including last Octoberís gift of $8 million to support the new Powell-Focht Bioengineering Building. Most recently, the Foundation established a $1 million endowment for scholarships and fellowships named in honor of the late Mr. Herbert Kunzel, boardmember of the Powell Foundation (p. 3).

The second Philanthropy Award was given to The Whitaker Foundation. The Whitaker Foundation is a private, nonprofit foundation dedicated to improving human health through the support of biomedical engineering. The Foundation was established in 1975 upon the death of U.A. Whitaker, founder and chief executive officer of AMP Incorporated, the largest manufacturer of electrical connectors and connecting devices. Most recently the Whitaker Foundation selected the Department of Bioengineering at UC San Diego as one of the first recipients of the new competitive Leadership Award. Through this program, the Foundation provided $14.2 million, along with a challenge grant of $3.8 million, to support recruitment of new bioengineering faculty members and construction of the Powell-Focht Bioengineering Building. The Leadership Award follows the Whitaker Foundationís 1993 Development Award, which allowed the Department to recruit new faculty, establish leading edge core research facilities, create innovative research and education programs, and establish itself as the first bioengineering department in the UC system.

The Outstanding Alumnus Award was given to Erik T. Engelson, class of 1984. Mr. Engelson received his B.A. in Microbiology and his M.S. in Bioengineering from UC San Diego. He also completed the Executive Program at Stanford Universityís Graduate School of Business. Mr. Engelson holds 45 patents in the biomedical field. In 1985, he co-founded and later became the general manager of Target Therapeutics, now a division of Boston Scientific Corporation. Target Therapeutics manufactures medical devices to access and treat vascular diseases of the brain. Mr. Engelson currently serves as executive-in-residence at Institutional Venture Partners, a venture capital firm in Northern California. He is also a director of The Foundry, LLC, a technology incubator for start-up companies, and MVMD, Inc., a company that manufacturers devices for stroke prevention. Mr. Engelson was named 1998 Inventor of the Year by the Silicon Valley Intellectual Property Law Association.


UCSD Biomedical Engineering Rises in Rank Yet Again

The Department of Bioengineering was ranked second in the nation, topped only by Johns Hopkins University, among bioengineering/biomedical specialty programs in the 1999 U.S. News & World Report survey released March 19, 1999. The Department of Bioengineering consistently ranks among the best programs in the nation. Shu Chien, Chair of the Department, says that "We can attribute this kind of recognition to the quality of our faculty, our students and our staff, as well as to our fruitful collaborations with the rest of UC San Diego, our neighboring research institutes and the biotechnology industry in San Diego."


Department of Bioengineering & UCSD Career Services Host

"Visit With Industry" - January 22, 1999 and

"Graduate Study in Bioengineering" - May 12, 1999

UCSD'S Department of Bioengineering co-sponsored a "Visit with Industry" with Career Services on January 22, 1999. Jorrie Miller, Bioengineering Undergraduate Affairs, coordinated the first ever "Visit with Industry", which proved to be a great success with over 70 undergraduates attending this informative presentation. Bioengineering faculty, Drs. Robert Sah and Sangeeta Bhatia co-moderated, and the panelists were: Three former UCSD undergraduates in Bioengineering and Bioengineering: Premedical students working in industry: Arlene Yang - GUIDANT, Deborah Williams Pia - AURORA BIOSCIENCES, Darren Sherman - EMERGENCY MEDICAL SUPPLIES; Two Industry representatives: Laurie Phillips - CYTEL CORPORATION, Kenny Dang - MEDTRONIC; Two Human Resource Representatives: Fred Rose - GUIDANT, Holly Chrzanowski - AURORA BIOSCIENCES; and UCSD'S Career Services Advisor: Lolly Murray.

The topics discussed were: How individuals entered bioengineering and what they do; the rewards and challenges of their jobs; typical entry level positions and where they can lead; what key skills/background/education/research/internships are needed for entry and advancement; resources on campus for securing employment; advice to someone considering a degree in bioengineering; and future trends in bioengineering.

The second panel co-sponsored with Career Services is "Graduate Study in Bioengineering". The panelists are: Professor Andrew McCulloch - Chair, Graduate School Admissions Committee, 2 current Bioengineering graduate students -Keith Herrman (GT), Sara Vaplon (UCSD), Current UCSD Senior who applied and was accepted to Bioengineering Graduate Schools - John Wright, Graduate Academic Advisor - Irene Jacobo, Career Services Professional and Graduate School Advisor - Nicole Moran O'Neil.

Planned Questions/Discussion: Is Graduate School and a M.S. or Ph.D. in Bioengineering for me? What is the nature of graduate study in Bioengineering? What are career opportunities for students after obtaining a Ph.D? a M.S.? What can I do as an undergraduate to find out if graduate school is for me (courses, research, internships)? How does one select Bioengineering Graduate Program(s) to apply to? What are the focus areas of different Bioengineering graduate school programs, and how can one find out more about the different programs? What has been your experience in applying to graduate school? What are the application requirements and their deadlines? How does the admissions committee select graduate students, and what can students do to enhance their chances of being accepted? What did UCSD'S Fall 1999's applicant / acceptance pool look like? What financial support is typically granted to Ph.D. & Masters students? What fellowships can I apply to?

Career Services videotaped these presentations so students who were unable to attend could go to Career Services and view the videotapes. The Bioengineering Department also obtained copies of the videos to be used in future undergraduate informational and advising meetings.


Profile of IBME Industrial Affiliate


Trega Biosciences and its wholly owned subsidiaries are engaged in the discovery, selection and early stage development of novel, small molecule drug therapies through combinatorial chemistry, biological screening and profiling and prediction technologies. The Company is a leading provider of novel drug leads and technology to the pharmaceutical and biotechnology industries for the development of new pharmaceuticals.

Trega, along with its subsidiary, NaviCyte, Inc., provide four essential components to efficient

drug discovery. First, Trega is a leader in the field of combinatorial chemistry, producing high quality libraries in large quantity, individual compound arrays. Currently, Tregaís small molecule chemistry is produced around novel structures that are provided to our customers in flexible formats that permit the rapid identification of active compounds against biological targets.

Second, Tregaís technology includes its recently acquired subsidiary, NaviCyte, Inc. ó The Drug Selection Company. NaviCyteís technology consists of proprietary systems, services and simulation models to address the newest drug discovery/development "bottleneck" - pharmacokinetic, metabolic and toxicological characterization of new drug entities.

Third, Trega has significant expertise in melanocortin biology, which encompasses the activities of a range of receptors that have been shown to play an important role in a number of major diseases, including inflammatory and metabolic diseases.

Finally, Trega utilizes proprietary high throughput screening technology for identifying active compounds in chemistry libraries for licensing to pharmaceutical companies.

Collaborations ó Biogen, Inc., Novartis Pharma AG, Ono Pharmaceuticals Co., Ltd., Warner-Lambert Co., Chugai Biopharmaceuticals, Isis Pharmaceuticals, SmithKline Beecham, Plc, Genentech, Inc., Schering-Plough, R.W. Johnson Pharmaceutical Research Institute
 
 

Key Contacts:
Michael G. Grey

President and CEO

Lawrence D. Muschek, Ph.D. 

President, Research and Development

Gerard A. Wills

Chief Financial Officer

George M. Grass, Pharm.D., Ph.D. 

President, NaviCyte, Inc.

Michael J. Green, Ph.D.

Vice President, Chemistry

Stephen F. Flaim, Ph.D., F.A.C.C.

Vice President, Biological Research & Development


Announcements

Three UCSD Irwin and Joan Jacobs School of Engineering faculty members have been elected to the National Academy of Engineering: Paul Libby, Professor Emeritus of Fluid Mechanics; Frieder Seible, Professor of Applied Mechanics and Engineering Sciences (AMES) and chairman of the Division of Structural Engineering; and Frank Talke, Professor of Mechanical Engineering and Endowed Professor in the Center for Magnetic Recording Research.

The Institute for Biomedical Engineering received a three-year $1.1 million National Science Foundation (NSF) Major Research Instrumentation grant, with Dr. Jeff Price as the Principal Investigator. The program will develop three new high-performance scanning cytometry systems. The systems will be the first instruments capable of performing quantitative, in situ cell-by-cell measurement on millions of cells over an entire microscope slide in only a few minutes. The NSF grant will convert the existing Confocal Microscopy Core Facility of the Institute for Biomedical Engineering into the NSF-Whitaker Quantitative Imaging and Confocal Microscopy Resource at UCSD.

The Department of Bioengineering received complete approval of its proposed Master of Engineering (M.Eng.) degree program in April, 1999. The Bioengineering M.Eng. program is specifically geared to train design and project engineers in the biotechnology industries and to fill a demonstrated need for professional training relative to industrial careers requiring integrated engineering sophistication with expertise in biology and medical science.

The most recent U.S. News & World Report survey of graduate programs (March 1999) ranked UCSD among the nationís best in engineering, medicine and science for the year 2000. The UCSD Irwin and Joan Jacobs School of Engineering received an overall ranking of 20 for the nation, up one from last year, and a big step from a rank of 43 only five years ago. UCSD Bioengineering rose to number two in the national ranking (p. 5). The UCSD School of Medicine was ranked 22nd among the nationís top 25 medical schools. In biological sciences, UCSD ranked 17th in the nation, while the physics program was ranked 18th and the mathematics department 17th.

Dirk-Uwe Bartsch, Ph.D. and William R. Freeman, M.D., members of the IBME and their collaborators at AutoQuant Imaging Inc. were awarded a phase 2 SBIR grant on high-resolution three-dimensional imaging of the posterior pole of the human eye. The grant will develop new methods in visualizing fine details with the help of software based image restoration techniques. Drs. Bartsch and Freeman have worked together with AutoQuant Imaging for the past several years on advanced computational imaging techniques in ophthalmology, using images generated with scanning laser ophthalmoscopes and conventional fundus cameras.



Outstanding Students to Begin Graduate Studies in Bioengineering

Seventeen new doctoral students, the largest number of Ph.D. admissions since the formation of the Department, will be joining the Bioengineering graduate program in September 1999. All have outstanding academic records and several are the recipients of prestigious extramural fellowships. As just one indication of the strong qualifications of these new doctoral students, the median GRE scores in all subject areas were within two points either side of the 90th percentile. The new graduate class will also include the new Master of Engineering degree program, which recently received final approval (p. 7). The new students come from diverse undergraduate backgrounds in mechanical, electrical and chemical engineering, biomedical engineering, biology, physics and chemistry. We are delighted they have chosen UCSD for their graduate studies and are looking forward to their arrival.


1999 Fall Doctoral Candidates

Maria Adolfson Royal Institute Of Tech Bioengineering

Ramses Agustin University of California Davis Mechanical Engineering

Dirk Albrecht UCSD Bioengineering

Jared Allen Brigham Young University Chemistry

Timothy Allen Duke University Bioengineering

Vicki Chin Ma MIT Chemistry

Christopher Flaim University of California Berkeley Engineering Physics

Charles Greenhut NY Suny at Stony Brook Mechanical Engineering

Travis Klein Harvey Mudd College Biomedical Engineering

Jennifer Marciniak University of Southern California Chemistry

Kevin Mcgowan Duke University Physics

Robert Mills Johns Hopkins University Bioengineering

Thomas Pisanic Johns Hopkins University Chemistry

Kori Rivard Michigan State University Bioengineering/ECE

Shula Stokols University Arizona Biomedical Engineering

Michele Temple UCSD Bioengineering

William Tyler University of Missouri Columbia Chemistry


Faculty Profile

Dr. Robert Sah

Dr. Robert Sah is currently Charles Lee Powell Associate Professor of Bioengineering at UCSD. Dr. Sah received the S.B. and S.M. in Electrical Engineering from the Massachusetts Institute of Technology in 1983 after completing a cooperative thesis project at Medtronic, Inc. Dr. Sah received the Ph.D. under the direction of Prof. Alan Grodzinsky in Medical Engineering from the Harvard/MIT Division of Health Sciences and Technology in 1990, and the M.D. from Harvard Medical School in 1991. He trained as an Arthritis Foundation Post-Doctoral Fellow with Dr. Stephen Trippel at Massachusetts General Hospital and Prof. Grodzinsky at MIT. In July 1992, Dr. Sah joined the UCSD Department of Bioengineering. Dr. Sah was a co-recipient with Prof. Grodzinsky of a Kappa Delta Award from the Orthopaedic Research Society in 1993. He received a Hulda Irene Duggan Investigator Award from the Arthritis Foundation in 1993 and a Young Investigator Award from the National Science Foundation in 1994. Currently, Dr. Sah serves as Advisor to the Undergraduate Biomedical Engineering Society and Chair of the Bioengineering Undergraduate Affairs Committee. Dr. Sah directs the Cartilage Tissue Engineering Laboratory at UCSD.

Articular cartilage is the connective tissue at the ends of long bones that functions as a low-friction wear-resistant load-bearing material. Millions of people are stricken with degenerative joint disease (osteoarthritis) and suffer from pain and impaired joint function. Unfortunately, there is no pharmacological treatment available currently to reverse the course of the disease. The end-stage therapy for degenerate joints is surgical replacement with metal and plastic prostheses. While such implants have been remarkably successful, they have limitations especially in active individuals due to loosening and generation of wear debris. A living tissue-engineered cartilage replacement may provide a long-term solution for damaged joints.

The tissue engineering of articular cartilage is actively being pursued in a number of academic and industrial laboratories. In 1997, autologous chondrocyte implantation was commercialized as Carticel™ (Genzyme Tissue Repair, Cambridge, MA) in the United States. In this procedure, a cartilage biopsy is taken from the patient, the chondrocytes are isolated, expanded in culture, and then injected into the defect under a periosteal tissue flap. An alternative clinical treatment is transplantation of a fresh osteochondral graft (living cartilage with a thin layer of underlying bone). Here, site-matched allogeneic donor tissue relatively non-weight bearing regions of a joint into a cartilage defect. While patients benefit from these treatments, the mechanistic basis and ways to achieve uniform and long-term positive outcome remain under active study. A number of companies, such as Advanced Tissue Sciences in La Jolla, are actively developing alternative cartilage tissue engineering therapies.

Dr. Sahís laboratory studies articular cartilage tissue engineering as well as the biophysical properties and biomechanical regulation of normal, repair, aging, and osteoarthritic articular cartilage.

Cartilage Tissue Engineering. In general, the repair of articular cartilage defects can be viewed as a number of discrete processes, including the integration of the new tissue with the surrounding host articular cartilage and the filling of the bulk of the defect with cartilaginous tissue. Such repair involves a variety of cellular and molecular processes including cell adhesion, migration, and proliferation as well as matrix remodeling. These processes may be regulated by the mechanical environment of diarthrodial joints, as imposed by intra-operative methods and post-operative rehabilitation protocols. Delineation of reparative processes and their regulation allows development and improvement of therapeutic approaches.

Normally, the integration of an engineered cartilage construct with the surrounding host cartilage does not occur effectively in vivo. To study this in more detail, Dr. Sahís lab developed a model system whereby cartilage tissue is explanted into uniform blocks and pairs are maintained in partial apposition during incubation in vitro. Here, the biochemical and biomechanical environment can be controlled, and bovine cartilage explants integrate moderately after several weeks in culture. The development of adhesive strength involves specific matrix remodeling mechanisms including collagen synthesis and crosslinking. These results suggest that the local cellular synthesis of appropriate molecules is required for integrative repair, and that delivery of cells to the interface may accelerate the integration process.

The method of delivery of an appropriate number of cells into a cartilage defect and ensuring their adherence is critical for successful cellular therapies. Using a flow chamber device, Dr. Sahís lab determined the adhesiveness of chondrocytes to cartilage. Initially, the chondrocytes attached weakly to cartilage and could be detached by gravitational forces. With time, chondrocyte became more strongly attached such that after 40 minutes of seeding, 30 Pa of shear stress was required for 50% cell detachment. These results suggest that the initial time period after cell transplantation is likely to be critical for the formation of stable interactions between transplanted chondrocytes and the surrounding host articular cartilage.

Once stably attached in a cartilage defect, transplanted chondrocytes may be regulated by biomechanical stimuli. The normal joint provides a biomechanical environment that is known to normally regulate the metabolism of chondrocytes. Compressive stress of a relatively low amplitude was found to markedly inhibited cell proliferation as well as matrix synthesis. Such biomechanical regulation of cell behavior may be an important determinant of cellularity in a defect and subsequent functional repair of the cartilage matrix.

Cartilage Biomechanics. Since cartilage provides biomechanical functions, the ultimate goal of cartilage tissue engineering is to develop a tissue that exhibits appropriate biomechanical properties. Traditionally, the mechanical properties of articular cartilage have been studied by reducing surface displacement and load measurements to tissue properties, assuming the tissue sample (1-5 mm thick for adult human cartilage) to be homogeneous. However, the composition, structure, and metabolism of articular cartilage vary markedly with depth from the articular surface. Using new methodologies, Dr. Sahís lab is determining the biomechanical properties of normal, aged, degenerate, repair, and tissue-engineered cartilage at a sub-tissue length scale.

Using fluorescently labeled chondrocytes as intrinsic fiducial markers, the spatially-varying strain within cartilage samples is determined during application of applied load. The normal articular cartilage of bovine knee joints and human hip joints exhibit dramatic depth-varying compressive properties, being relatively soft near the articular surface and relatively stiff near the subchondral bone. These results suggest that the superficial region of cartilage is especially important in distributing joint loads over a broad surface area of cartilage. How these spatially-varying functional properties relate to the molecular components of the cartilage matrix remains to be established.

These biomechanical results provide quantitative information that is useful not only for understanding joint function and dysfunction, but also for developing probes to diagnose cartilage biomechanical function. Theoretical biomechanical models are critically dependent on accurate estimates of cartilage material properties. Biomechanical test instruments, which are currently being developed to test the function of cartilage in human patients, are also dependent on models and parameters to reduce the test data to clinically useful information. In addition, the measured material properties provide design specifications for tissue-engineered cartilage.

Ultimately, cartilage degeneration results in altered joint structure and function. Previously, the adherence of India ink to cartilage surfaces has been used to identify sites of roughened cartilage. Using a calibrated digital imaging method, Dr. Sahís lab found that transection of the anterior cruciate ligament in an animal model of arthritis induces cartilage degeneration in characteristic sites. These sites of degeneration on the distal femoral condyle and tibial plateau appeared in apposing surfaces of cartilage. This provides evidence for the clinical dictum that focal regions of damaged cartilage lead to degeneration in the apposing cartilage surface. Ongoing studies are using this approach to judge the efficacy of interventions, both tissue engineering or pharmacological, as well as mechanistic processes involved in the physical regulation of cartilage degeneration.

REFERENCES

Ahsan T, Sah RL: Biomechanics of integrative cartilage repair. Osteoarthritis Cartilage 7:29-40, 1999.

Chang DG, Iverson EP, Schinagl RM, Sonoda M, Amiel D, Coutts RD, Sah RL: Quantitation and localization of cartilage degeneration following the induction of osteoarthritis in the rabbit knee. Osteoarthritis Cartilage 5:357-72, 1997.

Chen AC, Sah RL: The effect of static compression on proteoglycan synthesis by chondrocytes transplanted to articular cartilage in vitro. J Orthop Res 16:542-50, 1998.

Schinagl RM, Kurtis MS, Ellis KD, Chien S, Sah RL: Strength of chondrocyte adhesion to articular cartilage: effect of seeding duration. J Orthop Res 17:121-9, 1999.

Schinagl RM, Gurskis D, Chen AC, Sah RL: Depth-dependent confined compression modulus of full-thickness bovine articular cartilage. J Orthop Res 15:499-506, 1997.
 


Graduate Student Honors

Sara Vaplon, graduate student in Bioengineering, was awarded an American Heart Association Predoctoral Fellowship for her project, "Effects of Collagen Dysregulation on Structure an Mechanics of Normal and Post-Infarction Myocardium."

Dr. Peter Butlerís application for postdoctoral fellow (project on Physiology and Biophysics of Vascular Endothelium in Response to Shear Stress), was awarded an American Heart Association Postdoctoral fellowship and a National Institute of Health National Research Service Award.


IBME Faculty Honors

David Amiel, Professor of Orthopaedics, won the Societé Internationale de Recherche Orthopedicque et de Traumatologie (SIROT) 1999 Award for Research for his paper, "A Non-Viral Ex-Vivo Gene Therapy for the Repair of Full-Thickness Articular Cartilage defects," coauthored by Dr. Randal Goomer, a UCSD research fellow in orthopaedics. Dr. Amiel will present his work in Sydney, Austrailia next month at the SIROT/Societé Internationale de Chirugie Orthopedique et de Traumatologie meeting.

Shu Chien, Director of Institute for Biomedical Engineering and Chair of Department of Bioengineering, was elected as President-elect of the American Institute of Medical and Biological Engineering.

John Frangos, Professor of Bioengineering, was elected as a Fellow of the American Institute for Medical and Biological Engineering in March 1999.

Y.C. Fung, Professor of Bioengineering, received the Achievement Award from the San Diego Chinese American Science and Engineering Association in February 1999.

Marcos Intaglietta, Professor of Bioengineering received the Eugene M. Landis Award, the highest honor of the Microcirculatory Society, and delivered the Award Lecture on "Microcirculatory Deteminants in Artificial Blood," at the Annual Meeting in Washington D.C. on April 16, 1999.

Song Li, Assistant Project Scientist in Bioengineering, Benjamin P.C. Chen, Nobuyoshi Azuma, Ying-Li Hu, Steven Z. Wu, Bauer E. Sumpio, John Y.-J. Shyy and Shu Chien, published an article on "Distinct roles for the small GTPases Cdc42 and Rho in endothelial responses to shear stress," in the Journal of Clinical Investigation, in the April 15, 1999 issue. A figure in the article was chosen by the Journal of Clinical Investigation as the cover of that issue.

Andrew McCulloch, Professor of Bioengineering, J.L. Emery, Senior Engineer in the Biomechanics Group at Exponent, Failure Analysis Associates, and Jeffrey L. Omens, Assistant Professor of Medicine and Bioengineering, won Best Paper Award for their paper "Strain softening in rat left ventricular myocardium." Journal of Biomechanical Engineering 1997; 119 (1); 6 ó12, at the ASME International Congress in Anaheim in November 1998.

Bernhard Palsson, Professor of Bioengineering and Adjunct Professor of Medicine, published an article "Two new pseudopod morphologies displayed by the human hematopoietic KG1a progenitor cell line and by primary human CD34+ cells" in the November 15, 1999 issue of BLOOD. One of the figures in the article was chosen the BLOOD as the cover of that issue. The article also received awards from the Knowledge Distributed Intelligence (KDI) and the National Science Foundation (NSF).

Peter Wagner, Professor of Physiology, received the Honoris Causa degree from the University of Barcelona, Spain in April, 1999.


New Ph.D.ís

Drs. Fred Vetter, Walt Baxter, Tabassum Ahsan, Mohammad Sotoudeh, Shila Jalali, Jin Gang, William Lindsley and Douglas Chang of the Department of Bioengineering successfully defended their Ph.D. theses this spring, and will be receiving their degree at the commencement on June 13, 1999. Congratulations and Best Wishes!!
 

University of California, San Diego

Institute for Biomedical Engineering

9500 Gilman Drive

La Jolla, CA 92093-0427

(619) 822-2290