Mon, Dec 12, 2005 page2

• New technique to ease the pain

  SCIENTIFIC BREAKTHROUGH A Taiwanese doctor has created a new process for creating artificial cartilage that could promise relief for those suffering from joint pain

  • CNA
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  A casual chat and the application of crossover technology were the seeds that grew into a career for Li Wan-ju (李萬柱), culminating in the discovery of a way to create artificial cartilage, a technique that promises to help millions of patients around the world who suffer from damaged joints.

  Currently, for those who have serious joint damage caused by arthritis or injury, physiotherapy or artificial joint replacement are the only options, with replacement surgery being expensive and painful.

  However, a "nanofiber scaffold" developed by Li and his colleagues at the National Institute of Health in Bethesda, Maryland has succeeded in generating cartilage that offers a new option for patients.

  The story began in 1997, when Taiwan-born Li was studying for his master's degree at the Biomedical Engineering Graduate School at Drexel University in Philadelphia.

  The graduate from Taiwan's Chung Yuan University in Chungli was told by a teacher that the potential use of a largely ignored patent from 1938 had not been fully explored.

  The patent concerned the generation of fine fibers that are produced from a solution of gel-like particles when heavy electrical voltage is applied.

  The teacher said the spinning applied to the technique, which produces fibers with diameters measured in nanometers, had been widely used in textile manufacture, particularly in screen-making, but had not been studied for its possible use in medicine, although the fibers the process produces look like collagen fibrils -- analogous to the structures that support cells that produce bone and cartilage.

  Li's interest was piqued and he assembled his own equipment with components he bought at a local hardware store and began to electrospin fibers that lasted longer than those in previous experiments.

  Lee said that until 1998 his preliminary work focused on trying to control the diameter of the fibers he spun. Then he formed fibers with diameters of between 300 nanometers and 500 nanometers and began using them to fabricate scaffolds on which to grow human cells.

  His study was presented at the Sixth Annual World BioMaterials Conference in Kamuela, Hawaii in 2000, and has been cited more than 180 times by scientists around the world since it was published in a periodical in 2002.

  After entering the doctorate program at Thomas Jefferson University in Philadelphia, Li began to study the ways that cells implanted on electrospun nanofiber scaffolds grow.

  His study continued when he joined the National Institute of Health. He and his colleagues at the center's Cartilage Biology and Orthopedics Branch immersed human mesenchymal stem cells in an electrospun polymer scaffold and induced cells to grow.

  Stem cells, derived from the spinal cord, were chosen for the experiment because they can differentiate into a variety of specialized cell types, such as adipose, cartilage and bone cells.

  The scaffold is effective because its 700-nanometer diameter fibers imitate the collagen fibrils that support cells in the body. The fine fibers also degrade at an acceptably slow rate. They dissolve slowly enough to give the cells time to secrete collagen which replaces the scaffold.

  The difficulty is in balancing the pace that the scaffold degrades with the pace the collagen is produced by the cells. Li and the other team members had preliminary success in testing the tissue-engineered constructs in vivo.

  In 2002, Li cooperated with a surgeon at National Taiwan University Hospital in Taipei and cartilage Li produced on the polymer nanofiber scaffold was implanted into the foot of a pig.

  Six months after the operation, they cut into the pig's foot and found that the graft had grown as if it were a part of the pig foot, with no rejection at all.

  The success of the experiment suggested that patients whose joints are worn out because of age might be treated with artificial cartilage implants rather than having artificial replacements.

  Creating cartilage for human beings in the laboratory is still some years down the road, but Li believes this day will come, and even more applications for the technology will be discovered over time.
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