The study shows that delivering stem cells on a polymer scaffold to treat large areas of missing bone leads to improved bone formation and better mechanical properties compared to treatment with the scaffold alone. This type of therapeutic treatment could be a potential alternative to bone grafting operations.
"Massive bone injuries are among the most challenging problems that orthopedic surgeons face, and they are commonly seen as a result of accidents as well as in soldiers returning from war," said the study's lead author Robert Guldberg, a professor in Georgia Tech's Woodruff School of Mechanical Engineering. "This study shows that there is promise in treating these injuries by delivering stem cells to the injury site. These are injuries that would not heal without significant medical intervention."
Details of the research were published in the early edition of the journal Proceedings of the National Academy of Sciences on January 11, 2010. This work was funded by the National Institutes of Health and the National Science Foundation.
The study was conducted in rats in which two bone gaps eight millimeters in length were created to simulate massive injuries. One gap was treated with a polymer scaffold seeded with stem cells and the other with scaffold only. The results showed that injuries treated with the stem cell scaffolds showed significantly more bone growth than injuries treated with scaffolds only.
Guldberg and mechanical engineering graduate student Kenneth Dupont experimented with scaffolds containing two different types of human stem cells -- bone marrow-derived mesenchymal adult stem cells and amniotic fluid fetal stem cells.
"We were able to directly evaluate the therapeutic potential of human stem cells to repair large bone defects by implanting them into rats with a reduced immune system," explained Guldberg, who is also the director of the Petit Institute for Bioengineering and Bioscience at Georgia Tech.
Micro-CT measurements showed no significant differences in bone regeneration between the two stem cell groups. However, combining the two types of stem cells produced significantly higher bone volume and strength compared to scaffolds without cellular augmentation.
Although stem cell delivery significantly enhanced bone growth and biomechanical properties, it was not able to consistently repair the injury. Eight weeks after the treatment, new bone bridged the gaps in four of nine defects treated with scaffolds seeded with adult stem cells, one of nine defects treated with scaffolds seeded with fetal stem cells, and none of the defects treated with the scaffold alone.
"We thought that the functional regeneration of the bone defects may have been limited by stem cells migrating away from the injury site, so we decided to investigate the fate and distribution of the delivered cells," said Guldberg.
To do this, Guldberg labeled stem cells with fluorescent quantum dots -- nanometer-scale particles that emit light when excited by near-infrared radiation -- to track the distribution of stem cells after delivery on the scaffolds and completed the same experiments as previously described.
Throughout the entire study, the researchers observed significant fluorescence at the stem cell scaffold sites. However, beginning seven to 10 days after treatment, signals appeared at the scaffold-only sites. Additional analysis with immunostaining revealed that the quantum dots present at the scaffold-only sites were contained in inflammatory cells called macrophages that had taken up quantum dots released from dead stem cells.
"While our overall study shows that stem cell therapy has a lot of promise for treating massive bone defects, this experiment shows that we still need to develop an improved way of delivering the stem cells so that they stay alive longer and thus remain at the injury site longer," explained Guldberg.
The researchers also found that the quantum dots diminished the function of the transplanted stem cells and thus their therapeutic effect. When the stem cells were labeled with quantum dots, the results showed a failure to enhance bone formation or bridge defects. However, the same low concentration of quantum dots did not affect cell viability or the ability of the stem cells to become bone cells in laboratory studies.
"Although in vitro laboratory studies remain important, this work provides further evidence that well-characterized in vivo models are necessary to test the ability of regenerative tissue strategies to effectively integrate and restore function in complex living organisms," added Guldberg. "Improved methods of non-invasive cell tracking that do not alter cell function in vivo are needed to optimize stem cell delivery strategies and compare the effectiveness of different stem cell sources for tissue regeneration."
Guldberg is currently exploring alternative cell tracking methods, such as genetically modifying the stem cells to express green fluorescent protein and/or other luminescent enzymes such as luciferase. He is also investigating the addition of programming cues to the scaffold that will direct the stem cells to differentiate into bone cells. These signals may be particularly effective for fetal stem cells, which are believed to be more primitive than adult stem cells, according to Guldberg.
Lessons learned from the current work are also being applied to develop effective stem cell therapies for severe composite injuries to multiple tissues including bone, nerve, vasculature and muscle. This follow-on work is being conducted in the Georgia Tech Center for Advanced Bioengineering for Soldier Survivability in collaboration with Ravi Bellamkonda and Barbara Boyan, professors in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.
Other authors on the paper include Andres Garcia, professor and Woodruff Faculty Fellow in Georgia Tech's Woodruff School of Mechanical Engineering and the Petit Institute for Bioengineering and Bioscience; Georgia Tech research scientist Hazel Stevens, Georgia Tech graduate student Joel Boerckel; and National University of Ireland medical student Kapil Sharma.
This work was funded by grant number R01-AR051336 from the National Institutes of Health (NIH) and by grant number EEC-9731643 from the National Science Foundation (NSF). The content is solely the responsibility of the principal investigator and does not necessarily represent the official views of the NIH or NSF.
Research News & Publications Office
Georgia Institute of Technology
75 Fifth Street, N.W., Suite 314
Atlanta, Georgia 30308 USA
Media Relations Contacts: Abby Vogel (avogel@gatech.edu; 404-385-3364) or John Toon (jtoon@gatech.edu; 404-894-6986).
Writer: Abby Vogel
]]>Green Theme
The theme of the evening's event was sustainability and it was the first "green" event hosted by the College. Among the honored guests, 13 were inducted into the Council of Outstanding Young Engineers, 18 into the Academy of Distinguished Engineers, three into the Engineering Hall of Fame, and one individual was given an Honorary Engineering Award. The names of these honored recipients are listed below.
Accolades from the Dean
"The College of Engineering places a great deal of emphasis on quality and innovation" said Dean Don Giddens, a past recipient of the Academy of Distinguished Engineering Alumni Award in 1994, "and those honored at this event are true role models for future generation of engineers who demonstrate a solid technological Georgia Tech education, a competitive spirit, and drive for excellence."
2010 Council of Outstanding Young Engineering Alumni
Keefe Bohannan, EE '95
Elizabeth Boltz, ME '91
Angela Gill Folsom, BME '07
Eric Gebhardt, AE '90
Sara N. Johnson, TFE '00
Joy Jordan, ChBE '92
Timothy Langlais, ChE '05
Vivek Maddala, BEE '95
Sean McClenaghan, ChE '87
Parika Petaipimol, BME '04
Josh E. Rowen, CE '96
Mary A. Spio, MS EE '99
Bryan M. Swarn, PFE '03
2010 Academy of Distinguished Engineering Alumni
Michael Burnside, ME '74
Roland G. Caldwell, Jr., EE '88
David A. Dullum, ME ’70
Charles L. Harris, IE ’81
Christopher Hobson, ChE '79
Jay D. Humphrey, ESM ’82, '85
Stephen F. Jensen, CE’81
Susan Deal Kirchoff, CerE '80
Gregory J. Koch, CE ’90, MSCE '92
Robert D. Martin, IE '69
Stephen M. Mitchell, IE ’65, MS IE '67
Ted R. Meinhofer, Text '94
Thomas J. O’Brien, IE ’81
David Phelps, ME '81
Randall E. Poliner, BEE '77
Pedro A. Ray, EE ’82, '83
Gilberto Sarfaty, EES '81
2010 Engineering Alumni Hall of Fame
M. Andrew Clark, CerE '59
William R. T. Oakes, Jr., AE '59
Richard H. Truly, AE '59
2010 Honorary Engineering Award
George (Roy) L. Bowen III
The newly created executive vice president for research (EVPR) will report directly to the president and serve as a member of the president's cabinet.
The office will have overall responsibility for all research at Georgia Tech - faculty-based research as well as research conducted at GTRI and the Enterprise Innovation Institute - representing almost one-half of Georgia Tech's budget. College of Sciences Dean Paul Houston will chair the search committee.
In order for this individual to be in place prior to interviews with candidates for the provost position, the committee intends to conduct an internal search for the EVPR position, with the goal of having someone in place by March 2010. That committee includes:
"Our goal in forming this committee was to bring together a diverse group of interests, and I want to thank each member of the committee for serving the Institute in this capacity," Houston said. "The executive vice president will be entrusted with managing Georgia Tech's research enterprise and will benefit from broad-based support within our research community."
The committee hopes to hold its first meeting later this month. Nominations, recommendations, and comments may be directed to Dr. Houston.
]]>Maybe they could regrow the tissue: Grow the cartilage, grow the blood vessels, grow the nerves and even grow the bone.
]]>View full article: Soldier Survivability
For more information on Barbara Boyan lab, visit: Boyan Laboratory
]]>Dr. Boyan has demonstrated collaborative leadership in the emerging interdisciplinary field of tissue engineering in both academic and business domains. Dr. Boyan co-chairs the Preclinical Assessments subcommittee of the Tissue Engineered Medical Products F04 Division of ASTM. She has served as chair of the Orthopaedic Device Panel of the United States Food and Drug Administration and presently serves on the National Materials Advisory Board for the National Academies in the United States. Dr. Boyan also presently serves on the Boards of Directors of two NASDAQ companies: ArthroCare, Inc., and IsoTis, Inc., an orthobiologics company. In 1993, she co-founded OsteoBiologics, Inc. to develop tissue engineered medical products for treatment of bone and cartilage defects. The first generation of these products is now approved for use clinically both in the US and Europe and OsteoBiologics has been acquired by Smith & Nephew, Inc., an international medical device company. Dr. Boyan is also founder of Biomedical Development Corporation and Orthonics, Inc., which was recently acquired by Carticept Medical, Inc. In 2007, she co-founded SpherIngenics, Inc., which is developing technology invented at Georgia Tech.
Her research program is focused on bone and cartilage cell biology in the fields of orthopaedics and oral health. The author of more than 340 peer-reviewed papers, reviews, and book chapters, Dr. Boyan holds eight U.S. and international patents. She received the 2002 Clemson Award for Contributions to the Literature from the Society for Biomaterials for her research into cell response to material surfaces such as those used in implants and tissue engineering. She is particularly well known for her advancements in the area of rapid responses to steroid hormones; our understanding of how biomaterials affect cell and tissue behavior; and our recognition that inherent differences in cells from male and female donors may have a significant impact on the development of effective cell-based therapies.
Dr. Boyan has been instrumental in encouraging numerous women and men in their pursuit of academic and scientific careers. Her curriculum vita includes an impressive list of current and former advisees, and she has mentored and advised countless other undergraduate and graduate students, post doctoral fellows, and junior faculty. In 2000, she was recognized with the American Association for Dental Research Student Research Group Mentor Award. In addition, she promotes science and science education through her active participation in groups such as Leadership Texas and Leadership America, and she was the 2005 recipient of Atlanta Woman Magazine
]]>The experience reinforced Bumb's commitment to developing life-saving medical technologies. She'll continue to chase her dream next fall at Oxford where she'll pursue a Ph.D. in medical engineering as a recipient of a 2005 Marshall Scholarship.
"This may sound idealistic," said Bumb, "but I want to help come up with a new technology or treatment for a disease. I want to be the person who follows it through to make sure it reaches the people I'm developing it for," she said.
Bumb said she knows medical treatments won't help anyone if they can't be commercially viable. "You have to tailor the research to the market," she said. "For example, you develop drugs for Africa, not treatments that require lots of machines."
A senior in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Bumb plans to get her degree this spring, just three years after she enrolled on a Reginald S. Fleet President's Scholarship. "Being at Georgia Tech has changed what my future is going to be. It's offered me so many opportunities and the President's Scholarship gave me the opportunity to be at Tech," she said.
While at Tech, Bumb worked with associate professor Gang Bao on developing nanomolecular beacon tracking devices to map the territory of cells. This year, she's extending this research by designing a new tracking tool, a quantum dot, for vitamin D in the lab of professor Barbara Boyan. The quantum dot could be used to help treat bone and cartilage diseases such as osteoporosis and rickets.
"She's a natural leader and very insightful," said Boyan. "I have been struck by her systematic approach and her willingness to put in the hours necessary to tackle the problem in an organized and quite innovative way."
Bumb said academics aren't the only thing to get out of college. At Tech she served on the Georgia Tech Advisory Board, working with prominent business leaders to advise the administration on future goals. She also served in student government on the Joint Finance Committee, helping to decide how to allocate $3.5 million collected from the student activities fee.
"The finance committee was a huge learning experience in how to take resources to benefit the most people that you can," she said.
In addition, she helped found a new Indian dance team at Tech, Nazaaqat, which played to a packed house at the Ferst Center for the Arts.
Bumb is the sixth Georgia Tech student to win the Marshall, a scholarship established by the British Government for American students in 1953 in appreciation for assistance received after World War II under the Marshall Plan. The scholarship encourages potential leaders to become ambassadors for the United States and establish personal ties between the two countries.
Prominent former Marshall scholars include U.S. Supreme Court Justice Stephen Breyer; former U.S. Secretary of the Interior Bruce Babbitt; New York Times foreign affairs columnist Tom Friedman; and the scientist/inventor Ray Dolby.
Bumb said she hopes someday to fill the shoes of the Marshall Scholars who came before her. "Like most kids, when I was little I had dreams of saving the world - inventing a cure or finding the key to world peace," she said. "However as you get older everyone around you becomes more realistic and you push off idealism for practicality. Now I have returned to that childhood fantasy, actually seeing that there may be a chance of me being able to make an impact on the world in some way."
]]>