Human lung tissue engineering: a critical tool for safer medicines

In the field of human tissue-engineering, there has been a strong focus on the clinical aspects of the technology, i.e. repair, replace and enhance a given tissue/organ. However, much wider applications for tissue engineering (TE) exist outside of the clinic that are often not recognised, and include engineering more relevant models than animals in basic research and safety testing. Traditionally, research is initially conducted on animals or cell lines, both of which have their limitations. With regard to cell lines, they are usually transformed to enable indefinite proliferation. These immortalised cell lines provide the researcher with an almost limitless source of material. However, the pertinence of the data produced is now under scrutiny, with the suggestion that some historical cell lines may not be the cell type originally reported. By engineering normal, biomimetic (i.e. life-mimicking), human tissues with defined physiology (i.e. human tissue equivalents), the complex 3-dimensional (3-D) tissue/organ physiology is captured in vitro, providing the opportunity to directly replace the use of animals in research/testing with more relevant systems. Therefore, it is imperative that testing strategies using organotypic models are developed that can address the limitations of current animal and cellular models and thus improve drug development, enabling faster delivery of drugs which are safer, more effective and have fewer side effects in humans.