X chromosome inactivation and epigenetic responses to cellular reprogramming

Area of Science:

• Stem cell biology
• Epigenetics
• Genetics

Background:

• Induced pluripotent stem cells (iPSCs) are crucial for disease modeling and regenerative medicine.
• Reprogramming somatic cells into iPSCs involves significant epigenetic alterations.
• X chromosome inactivation (XCI), regulated by Xist, varies in human female iPSCs and embryonic stem cells (ESCs).

Purpose of the Study:

• To review the varying states of XIST expression in human female pluripotent stem cells.
• To explore the reasons behind these variations and potential countermeasures.
• To address safety concerns regarding pluripotent stem cells in regenerative medicine.

Main Methods:

• Review of existing literature on XIST expression and XCI in human iPSCs and ESCs.
• Analysis of the correlation between XIST expression, pluripotency, and developmental potential.
• Examination of transcriptional profiles associated with different XIST expression states.

Main Results:

• Human female iPSCs and ESCs exhibit diverse XIST expression patterns, defining three distinct cell classes.
• Unlike in mice, XIST expression does not strictly correlate with pluripotency in humans.
• Lack of XIST expression is linked to reduced developmental potential and upregulation of cancer-associated genes.

Conclusions:

• Variations in XIST expression significantly impact the characteristics and safety of human pluripotent stem cells.
• Further research is needed to understand and control XIST expression for therapeutic applications.
• Addressing XIST expression variability is critical for the safe and effective use of iPSCs in regenerative medicine.