Can we regrow a human arm? An overview and summary.

The honorary status of ‘‘Fellow of Biomaterials Science and Engineering’’ (FBSE) was established in April 1992 after the constituent biomaterials societies of the World Biomaterials Congress, now the International Union of Societies for Biomaterials Science and Engineering (IUSBSE), recognized the need for the public recognition of those members who have gained a status of excellent professional standing and high achievements in the fields of biomaterials science and engineering. Fellows are expected, through word and deed, to foster the field of biomaterials and to support its professional development as a practical and intellectual endeavor. Since 1992, every 4 years, the national and regional biomaterials societies of Australasia, Canada, China, Taiwan, Europe, India, Japan, Korea, Latin America, and the USA nominate their most prominent scientists for the honor of being inducted as Fellows into the International College of Fellows of Biomaterials Science and Engineering (ICF-BSE). Today, the ICF-BSE has 268 members. At the 8th World Biomaterials Congress in Amsterdam (June 2008), the ICF-BSE organized for the first time a ‘‘Special Fellows’ Session’’ as part of the scientific programming of the meeting. This first session was a traditional debate conducted by members of the ICF-BSE on the utility of animal experimentation as a predictive tool for the success or failure of a medical implant in humans. The debate pitched several speakers in favor of animal experimentation against an even number of speakers who argued for the opposing viewpoint. This lively debate was a welcome addition to the common presentation format and was well received by the audience. Four years later, at the 9th Biomaterials Congress in Chengdu, China (June 2012), the Special Fellows Session was devoted to the provocative question: ‘‘Can we regrow a human arm?’’ Considering that the ultimate goal of regenerative medicine is to restore both form and function of tissues and body parts that were lost due to trauma or disease, it was interesting to see how far we can possibly drive this concept. Historically, tissue engineers have been able to grow isolated human tissues in the laboratory. Skin, bone, muscle, and nerve are examples of isolated tissues that can be generated in the laboratory. Even more complex structures such as a functioning human bladder have been engineered from a biomaterials-based scaffold and autologous cells. However, there is currently no example of the successful regeneration of complex organs (such as heart or liver), or the clinical use of complex body parts (such as a whole joint, part of a limb, or facial features such as a living nose or ear). The reason the regeneration of complex organs or body parts is so challenging is our inability to control and guide the many different interactions among multiple cell types that have to be coordinated in order to grow a functional multi-cell structure. Simply stated, if the different cells, growth factors, signaling molecules, genes, and extracellular matrix components are the musicians in an orchestra, we do understand the actions and capabilities of most of the players, but we certainly lack the conductor who coordinates all the actions of the musicians in the orchestra. J. Kohn (&) New Jersey Center for Biomaterials, Rutgers – The State University of New Jersey, 145 Bevier Road, Piscataway, NJ 08854, USA e-mail: kohn@rutgers.edu