Evaluation of the Use of Induced Pluripotent Stem Cells (iPSCs) for the Regeneration of Tracheal Cartilage

Abstract

The treatment of laryngotracheal stenosis remains a challenge as treatment often requires multistaged procedures, and successful decannulation sometimes fails after a series of operations. Induced pluripotent stem cells (iPSCs) were generated in 2006. These cells are capable of unlimited symmetrical self-renewal, thus providing an unlimited cell source for tissue-engineering applications. We have previously reported tracheal wall regeneration using a three-dimensional (3D) scaffold containing iPSCs. However, the efficiency of differentiation into cartilage was low. In addition, it could not be proven that the cartilage tissues were in fact derived from the implanted iPSCs. The purpose of this study was to evaluate and improve the use of iPSCs for the regeneration of tracheal cartilage. iPSCs were cultured in vitro in a 3D scaffold in chondrocyte differentiation medium. After cultivation, differentiation into chondrocytes was examined. The ratio of undifferentiated cells was analyzed by flow cytometry. The 3D scaffolds were implanted into tracheal defects, as an injury site, in 24 nude rats. Differentiation into chondrocytes in vitro was confirmed histologically, phenotypically, and genetically. Flow cytometric analysis demonstrated that the population of undifferentiated cells was decreased. Cartilage tissue was observed in the regenerated tracheal wall in 6 of 11 rats implanted with induced iPSCs, but in none of 13 rats implanted with the control and noninduced iPSCs. The expression of cartilage-specific protein was also demonstrated in vivo in 3D scaffolds containing iPSCs. The presence of the GFP gene derived from iPSCs was confirmed in samples of cartilage tissue by the combination of laser microdissection (LMD) and polymerase chain reaction (PCR) techniques. Our study demonstrated that iPSCs have the potential to differentiate into chondrogenic cells in vitro. Cartilage tissue was regenerated in vivo. Our results suggest that iPSCs could be a new cell source for the regeneration of tracheal cartilage.