Selection Against Undifferentiated Human Embryonic Stem Cells by a Cytotoxic Antibody Recognizing Podocalyxin-like Protein-1

¹ Bioprocessing Technology Institute, 20 Biopolis Way, Centros, #06-01, Singapore 138668
² ES Cell International, 11 Biopolis Way, #05–06 Helios Building, 138667 Singapore, Republic of Singapore

^* To whom correspondence should be addressed. E-mail: andre_choo{at}bti.a-star.edu.sg.

	Abstract

Future therapeutic applications of differentiated human embryonic stem cells (hESC) carry a risk of teratoma formation by contaminating undifferentiated hESC. We generated 10 monoclonal antibodies (mAbs) against surface antigens of undifferentiated hESC, showing strong reactivity against undifferentiated, but not differentiated hESC (embryoid bodies). The mAbs did not cross react with mouse fibroblasts, and showed weak to no reactivity against human embryonal carcinoma cells. Notably, one antibody (mAb 84) is cytotoxic to undifferentiated hESC and NCCIT cells in a concentration-dependent, complement-independent manner. mAb 84 induced cell death of undifferentiated, but not differentiated hESC within 30 min of incubation, and immunoprecipitation of the mAb-antigen complex revealed that the antigen is podocalyxin-like protein-1. Importantly, we observed absence of tumor formation when hESC and NCCIT cells were treated with mAb 84 prior to transplantation into SCID mice. Our data indicate that mAb 84 may be useful in eliminating residual hESC from differentiated cells populations for clinical applications.