Building in vitro systems to study human reproductive medicine

Germ cells transmit totipotency and generate genetic diversity from one generation to the next. When sperm and egg fuse, a new life begins to develop by their genetic blueprints while incorporating epigenetic instructions. Kehkooi and his research team are fascinated by these processes and focus on understanding the molecular mechanisms underlying these processes, especially RNA binding proteins involved in regulating germ cell development, initiation of meiosis, and molecular and genetic factors causing infertility. Studies of human germ cell development, especially early germ cells, had been hindered by sample procurement and variation among different individuals. Human embryonic stem cells provide them unprecedented opportunity to develop in vitro differentiation systems to study these mechanisms. They have successfully built many novel in vitro differentiation and induction systems for human germ cells and their neighboring somatic cells, including spermatids, oocytes, and Sertoli cells. These in vitro systems also allow them to study the effect of microgravity on development of human germ cells in spacecraft.

Moreover, the research team have induced human stem cells to Sertoli cells which create an immune-privileged microenvironment and applied the technology to eradicate immune rejection during tissue transplantation.

1. Yan A, Xiong J, Zhu J, Li X, Xu S, Feng X, Ke X, Wang Z, Chen Y, Wang HW, Zhang MQ*, Kee K*. DAZL regulates proliferation of human primordial germ cells by direct binding to precursor miRNAs and enhances DICER processing activity. Nucleic Acids Res. 2022 Oct 24:gkac856. doi: 10.1093/nar/gkac856.

2. Hu W, Zeng H, Shi Y, Zhou C, Huang J, Jia L, Xu S, Feng X, Zeng Y, Xiong T, Huang W, Sun P, Chang Y, Li T, Fang C, Wu K, Cai L, Ni W, Li Y, Yang Z, Zhang QC, Chian R, Chen Z, Liang X*, Kee K*. Single-cell transcriptome and translatome dual-omics reveals potential mechanisms of human oocyte maturation. Nat Commun. 2022 Aug 30;13(1):5114. doi: 10.1038/s41467-022-32791-2.

3. Chen B, Zhu G, Yan A, He J, Liu Y, Li L, Yang X, Dong C, Kee K*. IGSF11 is required for pericentric heterochromatin dissociation during meiotic diplotene. PLoS Genet. 2021 Sep 7;17(9):e1009778. doi: 10.1371/journal.pgen.1009778.

4. Li L, Yang R, Yin C, Kee K*. Studying human reproductive biology through single-cell analysis and in vitro differentiation of stem cells into germ cell-like cells. Hum Reprod Update. 2020 Sep 1;26(5):670-688. doi:10.1093/humupd/dmaa021.

5. Liang J, Wang N, He J, Du J, Guo Y, Li L, Wu W, Yao C, Li Z, Kee K*. Induction of Sertoli-like cells from human fibroblasts by NR5A1 and GATA4. Elife. 2019 Nov 11;8. pii: e48767. doi: 10.7554/eLife.48767.

6. Jung D, Xiong J, Ye M, Qin X, Li L, Cheng S, Luo M, Peng J, Dong J, Tang F, Shen W, Matzuk MM, Kee K*. In vitro differentiation of human embryonic stem cells into ovarian follicle-like cells. Nat Commun.2017 Jun 12;8:15680. doi:10.1038/ncomms15680.

7. Li L, Wang B, Zhang W, Chen B, Luo M, Wang J, Wang X, Cao Y*, Kee K*. (2017). A homozygous NOBOX truncating variant causes defective transcriptional activation and leads to primary ovarian insufficiency. Hum Reprod 32(1): 248-255. doi:10.1093/humrep/dew271.

8. Li L, Zhou X, Wang X, Wang J, Zhang W, Wang B, Cao Y*, Kee K*. (2016). A dominant negative mutation at the ATP binding domain of AMHR2 is associated with a defective anti-Mullerian hormone signaling pathway. Mol Hum Reprod 22(9): 669-678. doi:10.1093/molehr/gaw040.

9. Lin J, Chen H, Luo L, Lai Y, Xie W, Kee K*. (2015). Creating a monomeric endonuclease TALE-I-SceI with high specificity and low genotoxicity in human cells. Nucleic Acids Res 43(2): 1112-1122. doi: 10.1093/nar/gku1339.

10. Kee K, Angeles VT, Flores M, Nguyen HN, Reijo Pera RA*. (2009). Human DAZL, DAZ and BOULE genes modulate primordial germ-cell and haploid gamete formation. Nature 462(7270): 222-225. doi: 10.1038/nature08562.

Awards:

2010, 2011,2017Bayer Investigator Award

2011Ten Outstanding Young Malaysian-Scientific and Technological development

2014Janssen Investigator Award

2014Tsinghua University ‘Outstanding Teaching Award’ (voted by students)

Lectures:

Medical cell biology

Stem cell biology

Extramural services:

2011-nowNational Natural Science Foundation of China(Grant Reviewer)

2012-2017Academic advisory board of State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Science

2013-nowThe Ministry of Science and Technology of China(Grant Reviewer)

2015-nowMedical Research Council, United Kingdom (Grant Reviewer)

2016-nowBeijing Municipal Science and Technology Commission(Grant Reviewer)

2017-nowInstitutional Review Broad for stem cell therapy, Peking Union Medical College

2019-now Advisory committee for life science and biotechnology of Chinese Spacecaft project

Patents:

US patent:9920300; Induction of germ cells from pluripotent cells; Inventors: Kee, Kehkooi; Reijo Pera, Renee.

China patent:201410730391.2;A chimeric nuclease specifically recognizes and edit mutations causing beta thalassemia, Chinese patent; Inventor: Jianfei Lin, Kehkooi Kee

China patent: 201710373412.3; In vitro differentiation of human embryonic stem cells into ovarian follicle and the culture medium; In ventor: Kehkooi Kee, Min Ye

China patent: 201810712206.5; A method to reprogram human fibroblasts to Sertoli cells and its application; Inventor:Kehkooi Kee, Jianlin Liang