TABLE 4.

Main characteristics of the three studies included in the review on cartilage stem/progenitor cells.

Studies	Species of cells	Sorts of cells	Recipient animal	In Vitro/in vitro	Scaffold	Definition of auricular cartilage differentiation	Conclusion
Kobayashi et al. (2011)	Human	PPCs, CSPCs a	Mouse	In vitro/in vitro	—	Histopathological examination (HE b , Safranin O/fast green, alcian blue, toluidine blue stain, and Elastica van Gieson stain) and immunohistology (collagen types I and II)	This is a unique report demonstrating the presence of stem cells in auricular cartilage
Otto et al. (2022)	Human	PPCs, CSPCs	—	In vitro	—	Histopathological examination (Safranin O) and immunohistology (collagen type II)	Auricular cartilage progenitor cells demonstrate a potent ability to proliferate without losing their multipotent differentiation ability and produce a cartilage-like matrix in the 3D culture
Zucchelli et al. (2020)	Human	CSPCs	—	In vitro	—	Histopathological examination (HE, alcian blue, alcian blue/periodic acid—Schiff and Alizarin red)	In 3D spheroids, microtic and normal CSPCs undergo a chondrogenic differentiation process, which results in tissues morphologically similar to native microtic and normal cartilage, respectively. The similarity we have observed between microtic and normal CSPCs with their tissues of origin were not apparent in 2D cultures

^a CSPCs, cartilage stem/progenitor cells.

^b HE, hematoxylin and eosin.