Table 2 Characteristics of human induced pluripotent stem cells compared to human embryonic stem cells

Cell source

Without the use of embryonic material Enable autologous cell transplantation

Technique for the generation of iPS cells

Simply trans-activating several transcription factors and/or exposure to several chemical components

Variables due to reprogramming methods and/or donor-parental cells

Morphology

Flat and tightly packed colony identical to hES cells

Proliferation potency

Unlimited self-renewal identical to hES cells

Pluripotency

Genes

OCT3/4, NANOG, SOX2 expression identical to hES cells

Gene promoter

OCT3/4, NANOG demethylation identical to hES cells

Cell surface antigens

SSEA3, SSEA4, TRA-1-60, TRA-1-81 positive identical to hES cells

Teratoma formation

Differentiation into three germ layers similar to hES cells

X chromosome inactivation (XCI)

Heterogeneity (complete XCI, partial XCI, pre-XCI) similar to hES cells

Mitochondria

Genome

Accumulated mtDNA mutations transmitted from parental cells Genetic mutations during reprogramming

Morphology

Globular shape with only small christae similar to hES cells and ES cell-like distribution

Function

Expression of nuclear factors involved in mitochondrial biogenesis

Telomere

Telomere elongation and ES cell-like telomerase activity

Epigenetic profile

Retention of somatic memory and aberrant methylation during the reprogramming process

microRNAs

Up-regulation of miR-302 cluster identical to hES cells