Embryonic stem cells release potentially novel hematopoietic factors

Area of Science:

• Stem Cell Biology
• Hematopoiesis
• Developmental Biology

Background:

• Standard long-term culture (LTC) of human primitive stem cells on mouse fibroblast feeders results in a significant decline of erythroid progenitor cells.
• This suggests critical factors supporting erythroid differentiation are absent in current culture conditions.

Purpose of the Study:

• To investigate if embryonic stem (ES) cell-conditioned media contains factors that improve erythroid differentiation and stem cell output in LTC.
• To identify factors regulating pluripotent stem cell proliferation and erythroid commitment.

Main Methods:

• Culturing human primitive stem cells using long-term culture (LTC) assays.
• Utilizing media conditioned by both undifferentiated and differentiating ES cells.
• Analyzing differentiation patterns and quantifying stem cell numbers (est.LTC-IC) in short-term and LTC assays.

Main Results:

• Media conditioned by undifferentiated ES cells increased estimated LTC-initiating cells (est.LTC-IC) and favored granulocytic differentiation.
• Media conditioned by differentiating ES cells significantly boosted est.LTC-IC numbers and potently promoted erythroid differentiation.
• Erythroid progenitors increased up to 100-fold and est.LTC-IC amplified up to 140-fold with differentiating ES cell media in LTC.

Conclusions:

• ES cell-conditioned media, particularly from differentiating cells, can significantly enhance erythroid progenitor generation and stem cell expansion in LTC.
• This study identifies a novel approach for discovering factors involved in stem cell proliferation, self-renewal, and commitment.
• Improved LTC conditions offer potential for stem cell expansion without compromising in vitro differentiation capacity for various applications.