Dysregulated gene expression during hematopoietic differentiation from human embryonic stem cells.

Area of Science:

• Stem cell biology
• Hematopoiesis
• Immunology

Background:

• Human embryonic stem cells (hESC) offer potential as an alternative donor source for transplantation.
• Functional defects in hESC-derived cells currently limit their application for complete lymphohematopoietic reconstitution.

Purpose of the Study:

• To define and quantify functional and molecular differences between hESC-derived and umbilical cord blood (UCB)-derived CD34(+) hematopoietic progenitor subsets.
• To investigate the molecular basis for impaired B lymphoid development from hESC.

Main Methods:

• Mesodermal differentiation of hESC to generate CD34(bright) and CD34(dim) progenitor subsets.
• Limiting dilution analysis to assess clonal proliferation, particularly in B lymphoid conditions.
• Analysis of transcription factor expression and negative regulators of lymphopoiesis (LNK, CEBPα).

Main Results:

• hESC-derived CD34(+) subsets displayed significant defects in clonal proliferation compared to UCB, especially for B lymphoid development.
• Aberrant expression of key transcription factors and exclusive expression of LNK and CEBPα were observed in hESC-derived cells.
• Knockdown of LNK partially rescued hematopoietic progenitor generation from hESCs.

Conclusions:

• hESC-derived hematopoietic progenitors possess an aberrant molecular profile, potentially due to persistent early developmental transcripts.
• This molecular signature contributes to a block in definitive hematopoiesis and impaired B lymphoid development from hESCs.
• Further research is needed to overcome these limitations for clinical applications of hESC-based therapies.