Uncovered - Man-made cartilage

Dong-An Wang is a runner up in the 2012 Materials Today cover competition.

Materials Today: Please can you start by introducing yourself, and telling us about your background?

Dong-An Wang: I am an Associate Professor (with Tenure) of Bioengineering in the School of Chemical and Biomedical Engineering (SCBE), Nanyang Technological University (NTU) in Singapore. I received my B.S. (1997) in Polymer Engineering and my Ph.D. (2001) in Polymer Science from Zhejiang University, China. I was a postdoctoral fellow, in turn, at the University of Tennessee Health Science Centre and Johns Hopkins University in the United States prior to joining the NTU faculty in 2005. Since June 2005, I have been appointed, in turn, as Assistant Professor (2005), Associate Professor (2010) and Associate Chair (2010) in SCBE, NTU.

My research focuses on biomaterials, tissue engineering and regenerative medicine with specialties of bioresponsive biomaterials for therapeutic 3D scaffolding and cell delivery; gene/antisense delivery for regenerative medicine; stem cells applications for tissue regeneration; and tissue-biomaterial integration for in situ tissue engineering.

Materials Today: Can you tell us about the materials you study, and the possible applications?

Dong-An Wang: I study functional biomaterials, with potential applications in tissue engineering and regenerative medicine; gene therapy and nanomedicine; drug delivery and controlled release.

Materials Today: What techniques do you use in your work?

Dong-An Wang: The techniques are: 1) co-encapsulation of removable micro-spherical porogens and non-anchorage dependent mammalian cells in hydrogel scaffolds; 2) formation of cell-laden micro-cavity hydrogel (MCG) constructs; 3) phase transfer cell culture (PTCC); 4) formation of tissue and hydrogel interpenetrating network; 5) non-invasive removal of hydrogel phase making scaffold-free tissue grafts.
These techniques are suitable to my studies because they are capable of creating 3D macro-sized, artificial scaffold-free hyaline (not fibrous) cartilage grafts.

To date, to fulfil all of the required demanded features in one construct, namely, being 3D, macro-sized, completely scaffold-free, and of a hyaline cartilaginous phenotype, this set of techniques remains unique.

Materials Today: What are the ‘big questions’ in your field of research?

Dong-An Wang: The ‘big questions’ are: 1) biocompatibility and biodegradation of biomaterials; 2) phenotypic consistency and functional competence of engineered tissues constructed with biomaterial scaffold; and 3) integration between biomaterials and host tissues after implantation.

Materials Today: What exactly is in the image?

Dong-An Wang: It is a piece of man-made living joint cartilage, named living hyaline cartilage graft (LhCG). It appears 3D sponge-like, is free of synthetic materials, and maintains a hyaline (not fibrous) cartilaginous phenotype. The image is a microscopic immune-histological photograph of LhCG, in which the green fluorescence represents type 2 collagen in the matrices; the blue fluorescent highlight represents chondrocyte nuclei (by DAPI); and the black areas represent empty pores in the bulk.