TABLE 3.

Main characteristics of the seven studies included in the review on perichondrial stem/progenitor cells.

Studies	Species of cells	Sorts of cells	Recipient animal	In vitro/in vitro	Scaffold	Definition of auricular cartilage differentiation	Conclusion
Derks et al. (2013)	Pig	ePPCs a , tPPCs b	Pig	In vitro	—	Histopathological examination (HE d , pentachrome, and alcian blue stain) and immunohistology (collagen type II)	Due to a high proliferative activity and a high chondrogenic capacity, ePPC might be a suitable cell source for cartilage tissue engineering
Kagimoto et al. (2016)	Monkey	PPCs c	Monkey/nude mouse	In vivo	—	Histopathological examination (Blyscan assay, HE, alcian blue, and Elastica van Gieson stain) and immunohistology (collagen type II)	The autologous transplantation of cartilage progenitors is potentially effective for reconstructing elastic cartilage
Oba et al. (2022)	Human	PPCs, ACCs	Nude mouse	In vivo	—	Histopathological examination (Blyscan assay, HE, alcian blue, and Elastica van Gieson stain) and immunohistology (collagen types I and II)	We succeeded in developing human auricular perichondrial chondroprogenitor cell-derived elastic cartilage in vitro that exhibits superficial effects when transplanted craniofacially, without major post-transplantation shrinkage
Togo et al. (2006)	Rabbit	PPCs, BMMSCs	Nude mouse	In vitro/vivo	Collagen sponge	Histopathological examination (toluidine blue and Elastica van Gieson) and and immunohistology (collagen type II)	Rabbit bone marrow mesenchymal stem cells used as controls could regenerate significantly smaller cartilage than perichondrocytes in the implant study
Xue et al. (2016)	Pig	PCCs, CSPCs	—	In vitro	—	Histopathological examination (toluidine blue)	We isolated cell populations from auricular cartilage and perichondrium and confirmed their stem cell properties by expression of stem cell surface marker, colony forming assay, and multiple differentiation potential
Zhang et al. (2019)	Pig	PCCs, CSPCs	—	In vitro	—	Histopathological examination (toluidine blue)	CSPCs showed a significant advantage in chondrogenesis in vivo with upregulated chondrogenic genes, a stable cartilage phenotype, and good mechanical properties
Otto et al. (2018)	Horse	BMMSCs, ACCs, PPCs	—	In vitro	GelMA hydrogel	Histopathological examination (HE and Safranin O/fast green) and immunohistology (collagen types I, II, and VI)	Although under the current culturing conditions, bone marrow-derived MSCs seemed to perform better in terms of matrix production, major advantages of ACPCs include the ability to generate high cell numbers, upregulation of the elastin gene, and a limited endochondral ossification potential

^a ePPCs: ear perichondrial progenitor cells.

^b tPPCs: tracheal perichondrial progenitor cells.

^c PPCs: perichondrial progenitor cells.

^d HE: hematoxylin and eosin.