Tissue engineering for pulmonary diseases: insights from the laboratory.

Recent advances in stem cell research and tissue engineering have opened new paradigms for future therapies towards many intractable diseases. Many tissue engineering approaches are also applied in the pulmonary research field. Several materials have been utilized as scaffolds to support lung tissue engineering to recapitulate the three-dimensional (3D) structure of the lung. Natural products and synthetic polymers are the two major components of the scaffold materials. Decellularization of allogeneic or xenogenic donor lungs is also utilized to obtain biological 3D matrix scaffolds. Decellularized lungs are recellularized with stem or progenitor cells. Cell sources are the key components for tissue engineering. The best cell source for tissue engineering is autologous cells obtained from patients because it does not induce an immunological response after transplantation. However, the stem/progenitor population in adult organs is generally small, and their capacity for proliferation or differentiation is limited. Knowledge about the endogenous stem/progenitor population in lung tissue has been expanded recently. Although the lung is the most challenging organ for tissue engineering because of its complex 3D structure and more than 40 different cell types, several breakthroughs in respiratory research have been made. These results give us a greater understanding of the possibilities and the limitations of tissue engineering for pulmonary diseases.