Spermatogonial stem cells: Current biotechnological advances in reproduction and regenerative medicine

Table 1 Summary comparison of characteristics of embryonic stem cells and spermatogonial stem cells in the context of transgenesis tecniques

Trait	Embryonic stem cells	SSCs
Mutagenesis technical status	Available for mice. Many genes mutated	Experimental level in mouse[75], rats[78], goats[81], pigs[82]
Source	Embryo	Adult testis
Age of derivation	Embryonic period	Postnatal period
Ethical/legal concerns	Yes	No
Efficiency		5 × to 10 × higher than with ES cells
Cell differentiation state	Undifferentiated - pluripotential	Differentiated up to germ-line
Tumorogenesis	Produce teratomas	Do not produce teratomas
Chimera formation	(+)	(-)
Germline gene transmission	Do not transmit genes from one generation to the next	Transmit genes from one generation to the next
In vitro phenotype	Colonies with tightly attached cells	GS cells loosely attached (easily dissociated with trypsin)[2]
Speed of growth	Faster	Slower
Requires other non-transfected SSCs during culture	No	Yes2
Karyotype	Variable - unstable1	Normal - stable
Epigenetics	Variable - unstable DNA methylation pattern	Normal - stable DNA methylation pattern
Offspring	Abnormal	Normal

Otherwise specified, information presented is based on[2]:

¹Often lose their germ cell potential due to trisomy[16];

²Spermatogonial stem cells (SSCs) that proliferate in culture (GS cells) require specific non-transfected SSC densities during the process of drug selection[118]. ES: Embryonic stem.