. 2021 Jul 1;11:16. doi: 10.1186/s13395-021-00265-6

Table 1.

Summary of endogenous murine skeletal muscle fibro-adipogenic progenitors

Murine cell	Canonical Markers	Alternative markers	Negative markers	Localization	Differentiation potential	Additional comments	References
Embryonic-fetal FAPs	PDGFRα TCF7L2/TCF4 Osr1	Osr2 Hox11 Tbx3 Tbx4 Tbx5 Sca-1^a CD34^a Adam-12 Tie-2^a	CD45 CD31 Ter119 α7-Integrin	Muscle-associated connective tissue and muscle interstitium	Robust in vitro adipogenic and fibrogenic differentiation but low chondrogenic and no detectable osteogenic or myogenic potential. Osr1+ progenitors also give rise to embryonic fibroblast-like cells in the dermis and FABP4+ adipocytes in white fat pads	Little is known about their origin, fate, gene regulation, function, stemness, and self-renewal	[24]; [26]; [57];
Adult FAPs	PDGFRα SCA-1	Hic1 CD90 Decorin (Dcn) PDGFRβ^b Col1a1^b TCF7L2/TCF4^b CD34^b Adam-12^c Tie-2^c Gli1^d	CD45 CD31 Ter119 α7-Integrin NG2/Cspg4 Rsg5	Fascia, epimysium, perimysium, and endomysium; abundant as perivascular cells	Adipocytes, myofibroblasts, osteocytes, and chondrocytes after muscle injury and in vitro, with no myogenic potential	Required for adult skeletal muscle regeneration and homeostasis; cellular and molecular dysfunction in pathology and disease	[11, 12, 27, 28]; [1]; [13]; [58]; [14]; [58]; [59]; [60]; [61]; [62], [2, 15, 53, 63, 64];

Murine cell

Canonical Markers

Alternative markers

Negative markers

Localization

Differentiation potential

Additional comments

References

Embryonic-fetal FAPs

PDGFRα

TCF7L2/TCF4

Osr1

Osr2

Hox11

Tbx3

Tbx4

Tbx5

Sca-1^a

CD34^a

Adam-12

Tie-2^a

CD45

CD31

Ter119

α7-Integrin

Muscle-associated connective tissue and muscle interstitium

Robust in vitro adipogenic and fibrogenic differentiation but low chondrogenic and no detectable osteogenic or myogenic potential. Osr1+ progenitors also give rise to embryonic fibroblast-like cells in the dermis and FABP4+ adipocytes in white fat pads

Little is known about their origin, fate, gene regulation, function, stemness, and self-renewal

[24]; [26]; [57];

Adult FAPs

PDGFRα

SCA-1

Hic1

CD90

Decorin (Dcn)

PDGFRβ^b

Col1a1^b

TCF7L2/TCF4^b

CD34^b

Adam-12^c

Tie-2^c

Gli1^d

CD45

CD31

Ter119

α7-Integrin

NG2/Cspg4

Rsg5

Fascia, epimysium, perimysium, and endomysium; abundant as perivascular cells

Adipocytes, myofibroblasts, osteocytes, and chondrocytes after muscle injury and in vitro, with no myogenic potential

Required for adult skeletal muscle regeneration and homeostasis; cellular and molecular dysfunction in pathology and disease

[11, 12, 27, 28]; [1]; [13]; [58]; [14]; [58]; [59]; [60]; [61]; [62], [2, 15, 53, 63, 64];

^aThese markers have not been studied in the embryo with detail

^bThese markers are also expressed by different cell types, including satellite cells, pericytes, and endothelial cells

^cAdam-12 and Tie-2 expression appears to be restricted for a subpopulation of FAPs

^dGli1 defines a subpopulation of murine muscle FAPs with pro-myogenic and anti-adipogenic functions [65]