Isolation and Chondrogenic Differentiation of Porcine Perichondrial Progenitor Cells for the Purpose of Cartilage Tissue Engineering

In vivo, cartilage has a limited regenerative capacity. Clinical replacement strategies require a suitable cell source to provide a stable chondrocyte phenotype without hypertrophic cartilage development, while being broadly available, and harboring a high proliferative potential. Thus, the aim of this study was to analyze the proliferation and chondrogenic differentiation capacity of porcine perichondrial progenitor cells (PPC) isolated from auricular (ePPC) and tracheal cartilage (tPPC) as an alternative cell source to mesenchymal stem cells (MSC). The proliferative potential of these cell types was analyzed by means of doubling times. Cell pellets were cultured in chondrogenic differentiation medium for 4 weeks. Potential chondrogenic differentiation was investigated by histology and immunohistology in addition to gene expression analysis of the cartilage markers collagen II, aggrecan, cartilage oligomeric matrix protein (COMP), the precartilage marker collagen I, and the hypertrophic cartilage marker collagen X. PPC showed a proliferative behavior comparable to that of MSC. Chondrogenic stimulation resulted in a higher expression of collagen II, aggrecan, and COMP in ePPC as compared to tPPC and MSC, whereas the expression of collagen I was comparable in all cell types independently of differentiation stimulation. Collagen type X, however, could not be detected. The production of cartilage-like extracellular matrix components in PPC pellets was confirmed by histological and immunohistological stains. Elastin, a component of auricular cartilage, however, was not detected in ePPC-derived pellets. Thus, PPC present a promising cell source for tissue engineering of cartilage. Furthermore, ePPC may be more convenient than tPPC due to their higher chondrogenic potential and better accessibility.