In vivo tumor formation from primate embryonic stem cells

Area of Science:

• Reproductive Biology
• Stem Cell Biology
• Immunology

Background:

• Human embryonic stem (ES) cells hold promise for transplantation therapies.
• Allogeneic transplantation models in nonhuman primates are crucial for advancing these therapies.
• Fetal environments offer potential advantages for cell engraftment due to immune immaturity.

Purpose of the Study:

• To evaluate the engraftment potential of cynomolgus ES cells in an allogeneic fetal transplantation model.
• To assess the immunological response and tissue integration of transplanted ES cells in a fetal host.
• To identify risks associated with ES cell transplantation in a developing organism.

Main Methods:

• Genetically marking cynomolgus ES cells with green fluorescent protein (GFP).
• Transplanting GFP-marked ES cells into allogeneic fetuses.
• Analyzing fetal tissues at 3 months post-transplantation for engraftment and teratoma formation using fluorescence and in situ PCR.

Main Results:

• Successful engraftment of transplanted ES cells was observed in multiple fetal tissues (approx. 1% of progeny).
• Transplanted cells integrated solitarily and were indistinguishable from host cells.
• Teratoma formation occurred when ES cells entered inappropriate spaces, such as the thoracic cavity.

Conclusions:

• Cynomolgus ES cells can engraft within allogeneic fetuses.
• Fetal transplantation is a viable model for studying ES cell behavior.
• Tumorigenesis risk necessitates precise control over ES cell localization during transplantation.