REPRODUCTIVE ENDOCRINOLOGY AND SCIENCE
, Head, Section on Implantation and Oocyte Physiology
D. Randall Armant, PhD, Adjunct Scientist
Somjate Manipalviratn, MD, Research Fellow
Zhi-Bin Tong, MD, Staff Scientist
Brian Kilburn, BS, Technician
Through basic and translational research, we seek (1) to identify critical cellular and molecular events required for successful implantation in pregnancy and (2) to understand the relationships between such events and pathologies of early pregnancy. Therefore, our objective is to understand the biology of the developing blastocyst, which requires the differentiation of its outer epithelium, the trophectoderm, into invasive trophoblast cells and the maintenance of a cohort of pluripotent embryonic stem cells.
Investigation of the interactions between the uterine endometrium and implanting blastocyst at the inception of pregnancy
Regulation of blastocyst development. Using in vitro approaches with both mouse and primate animal models, we investigate the role of the maternal environment in the development of per- and peri-implantation embryos. Previous work with mouse blastocysts revealed signaling pathways regulated by oxygen, growth factors, and the extracellular matrix; these pathways advance the intrinsic developmental program of the trophoblast. In the coming year, we plan to extend our studies of trophoblast differentiation and examine how the microenvironment sustains the pluripotent embryonic stem cell population within the blastocyst. Our collaborator Carol Brenner has established the rhesus monkey pre-implantation embryo model and works with several rhesus embryonic stem cell lines. The planned studies will provide needed information on the comparative physiology of mouse and primate embryonic development and implantation.
Nuclear and cytoplasmic damage of preimplantation embryos. Fluorescent in situ hybridization analysis of blastomeres from pre-implantation embryos of young rhesus macaque females revealed a high chromosomal abnormality frequency that was surprisingly similar to rates of in vitro–produced (IVP) human embryos. In the coming year, we plan to study monkey IVP embryos from older female animals and animals subjected to various ovulation induction regimes. We are assessing mitochondrial replication and function to determine their impact on cytoplasmic cellular components, as the mitochondria is central to energy and toxicity management. The proportion of mtDNA deletions is significantly higher in stimulated oocytes and embryos from rhesus macaques than in immature, unstimulated oocytes derived from ovaries of age-matched monkeys. These findings validate non-human primates as a model for investigating reproductive mechanisms relevant to human infertility.
Metabolomics of frozen-thawed immature human oocytes
Given that ATP is a principal donor of free energy and phosphate in many intracellular metabolic reactions and signal transduction pathways, we measure ATP levels in oocytes after the freezing/thawing process and in fresh oocytes. (Human oocytes from stimulated IVF cycles are discarded because of their nuclear immaturity.) ATP levels in surviving frozen/thawed oocytes are significantly lower than those in fresh oocytes. The extremely low level in frozen/thawed oocytes is the result of cryopreservation, but, once the mitochondria begin to function after thawing, the ATP level rises to close to that of fresh oocyte. We are continuing our study to measure the ATP level in a larger number of oocytes and will extend our study by incubating post-thawed oocytes for either 2 or 3 hours to demonstrate the effect of the incubating time after thawing.
Publications Related to Other Work
Feinberg EC, Levens ED, DeCherney AH. Infertility surgery is dead: only the obituary remains? Fertil Steril 2007 [E-pub ahead of print].
Levens ED, Scheinberg P, DeCherney AH. Severe menorrhagia associated with thrombocytopenia. Obstet Gynecol 2007;110:913-7.
COLLABORATORS
Carol A. Brenner, PhD, Wayne State University School of Medicine, Detroit, MI
Sudhansu K. Dey, PhD, Vanderbilt Medical Center, Nashville, TN
Richard E. Leach, MD, Michigan State University, Lansing, MI
Nita Mahile, PhD, Yale Medical Center, New Haven, CT
Roberto Romero, MD, Program in Perinatal Research and Obstetrics, NICHD, Detroit, MI
Susan M. Smith, PhD, University of Wisconsin, Madison, WI
For further information, contact decherna@mail.nih.gov.
