Generation Of Immune Tolerant And Immune Compatib Human Pluripotent Stem Cell For Cell Therapy

Pluripotent stem cell, incuding human embryonic stem cells (ES cells) and induced pluripotent stem cells (iPS cells), can be maintained as a pluripotent, self-renewing population. Theriotically, pluripotent stem cells may provide unlimited source for cell transplantation-based treatment, which makes them become the ideal seed cells. One major challenge of cell therapy is the rejection by the transplant recipient. Pluripotent stem cells are certainly no exception. This study was designed to develop methods either to improve immune tolerance or to make completely immune compatible cells for cell therapy.1. Generation of immune tolerant hES cell line by stable HLA-G expression. HLA-G is one of the key molecules involving in pregnancy and engraftment tolerance. We established human ES cell line with stable HLA-G expression. These ES cells have been shown to present a stable diploid karyotype and maintained self-renewal and pluripotency. They are Oct4 and Sox2 positive cells and formed teratoma in SCID mice. While differentiating HLA-G1+hESCs into neural progenitor cells (NPCs), HLA-G1 was stably expressed in the differentiated cells. Cytotoxicity assay and mixed lymphocyte reaction (MLR) suggested HLA-G protected hESC-derived NPCs from attacking in vitro.2. Improve the effeciency of iPS cells, make immune compatible transplant cells and explore mechanism underlying iPS cell induction. In this study, human neural progenitor cells were used for genetic reprogramming by applying single molecule - Oct4, instead of the four Yamanaka factors Oct3/4, Sox2, Klf4, and c-Myc. Our results showed that Oct4 alone was sufficient to reprogram human NPCs into iPS cells. The reprogramming efficiency was 0.015±0.001, about 10-fold higher than that of human skin fibroblast cells using 4 factors system. Comparing these human NPC-derived iPS cells (NiPS) with hES cells, they had similar gene expression profiling, DNA methylation pattern,expressed all pluripotent markers and maintained pluripotency. Hence, we generated iPS cells from human NPC by using Oct4 alone, moreover, the efficiency of inducing NiPS by oct4 is much higher that that of fibroblast.