**9. Decellularized respiratory tissues and stem cells**

There are reports of fabricated decellularized tissue used as potential scaffolds for respiratory tissue because of their simplified anatomical structure. One of the earliest reports on the fabrication of scaffold for tracheal tissue regeneration is [49] where the authors compared the efficiency of decellularized leporine tracheal scaffold seeded with amniotic-derived mesenchymal stem cells and non-seeded decellularized scaffolds. The authors concluded that MSC-seeded scaffold exhibited a high level of survival of the cells and epithelialization as well as a high level of elastin.

In another study on decellularized tissue, Nichols and colleagues fabricated acellular pig scaffolds using decellularized scaffold seeded with murine embryonic stem cells, pig bone marrow-derived mesenchymal stem cells, and primary human alveolar epithelial type II cells [45]. They concluded that there were recorded changes in type I collagen levels and evidences of cell attachment and viability.
