Maria Giakoumopoulos
Major Professor: Dr. Ted Golos
Email: giakoumopoul@wisc.edu
Telephone: (608) 263-7705
Degree Objective: Ph.D. Endocrinology and Reproductive Physiology
Background: B.A. Univeristy of Rochester, Biology and Cultural Anthropology
M.S. Danube University of Krems, Austria, Clinical Embryology
Current Research Projects:
A substantial number of pregnancies fail within the first weeks, most likely due to failure upon implantation of the embryo to properly form the placenta. However, these early events are difficult to investigate in humans because of ethical concerns regarding research with human embryos, as well as experiments with pregnant women. Our laboratory has shown recently that when human embryonic stem cells (hESC) are allowed to form embryoid bodies, they will differentiate to trophoblasts and secrete high levels of placental hormones. What is most interesting about these experiments is that the highest differentiation occurs when the ESC are allowed to form embryoid bodies (EBs), and are transferred into a three-dimensional (3D) extracellular matrix environment (ECM). However, even in this environment, the formation of structures that resembled complete chorionic villi with appropriate morphogenesis were not seen.
Thus, we are interested in understanding the role that these 3D forces may play in trophoblast differentiation, and we hypothesize that cues from non-trophoblastic cells could direct placental morphogenesis in the correct 3D environment. We propose a co- culture system to achieve this goal and will utilize different 3D scaffolds as well as various effector cell types to drive differentiation.
Our first experiments entail the use of 2 types of placental fibroblasts as effector cells in a co-culture, suspension paradigm: one from term placentas (TPF), the other from chorionic villus sampling (CVS), and dermal fibroblasts (CI2F) as a non-placental fibroblast control. We have made substantial progress in this experiment and have shown that combination EBs made with all 3 effector cell types showed greater CG secretion than EB controls made without effector cells. Similar combination experiments were completed with SV40 transformed human umbilical vein endothelial cells (HUVEC- CS) but EBs were not readily made when using these effector cells. This may be due to possible protease secretion or inhibitory signals from the endothelial cells. Alternate possibilities would be to use fetal endothelial cells derived from hESC or a primary endothelial cell line. These types of endothelial cells would be similar to the in vivo cells encountered during embryo implantation.
It has also been shown that when tumor explants are plated on collagen I and the explant containing collagen is released, the collagen would wrap around the explant and encapsulate it. This 3D environment allowed for live imaging of the gels and examination of a 20 vs. 3D environment in a simple matrix. Thus our second experiment entails the use of 50-100 EBs that will be plated on 20 ~g/sq. cm Collagen IV and then the gel will be released into the EB medium. This experiment will allow specific examination of 20 vs. 3D effects in a simple collagen gel.
Our third experiments entail the use artificial scaffolds such as Alginate and Polyethylene Glycol (PEG) that allow us to add individual adhesion molecules and growth factor cues to be able to isolate specific effects on trophoblast differentiation. Preliminary studies have shown that compared to Matrigel and Alginate, PEG alone and PEG tagged with the peptide I KVAV from the laminin recognition domain, did not promote hCG secretion in EBs. These preliminary results can be utilized to identify the possible changes needed in the PEG scaffolds. The variables that will be pursued will be porosity, flexibility of the scaffold, and the addition of adhesion signals allowing for an increase in cell migration and differentiation.
Honors and Awards:
- NIH T32-HD041921-04
Presentations:
Oral Presentation: Stem Cell Program Retreat - November 2006
Poster Presentation: Society of Gynecological Investigation - March 2007
Publications:
1. Giakoumopoulos, M, Garthwaite MA, Golos TG. (2008) Chapter titled: Human embryonic stem cells: a model for trophoblast differentiation and placental morphogenesis. Stem Cells in Human Reproduction (in press).
2. Giakoumopoulos M, Siegfried LM, Garthwaite MA, Golos TG. (2008) Co-culture Effects on Trophoblast Differentiation from Human Embryonic Stem Cells (in preparation).
Other Publications:
Giakoumopoulos M. (2008) Chapter on In Vitro Fertilization. Encyclopedia of Stem Cell Research.
National Presentations:
1. Giakoumopoulos M, Siegfried LM, Garthwaite MA, Golos TG. (2007) Co-culture Effects on Trophoblast Differentiation from Human Embryonic Stem Cells. 54th Annual Meeting of the Society for Gynecologic Investigation, Reno, NV, March 14-17, Abstract 804.
2. Giakoumopoulos M, Garthwaite MA, Golos TG. (2008) The Effects of Spatial and Mechanical Interactions of Collagen I on Human Embryoid Body-Derived Trophoblast Differentiation. 6th International Society of Stem Cell Research Annual Meeting, Philadelphia, PA, June 11-14, Abstract 606.
3. Giakoumopoulos M, Garthwaite MA, Golos TG. (2008) The Effects of Spatial and Mechanical Interactions of Collagen I on Human Embryoid Body-Derived Trophoblast Differentiation. 2008 World Stem Cell Summit, Madison, WI, September 22-23.