טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentVladimirov Faina
SubjectThe Ability of Embryonic Stem Cells to Differentiate
and Integrate in the Gastrulation Stage Chicken
Embryo
DepartmentDepartment of Medicine
Supervisor Professor Thomas Schultheiss


Abstract

The Modification of the genome of animal species is one of the major tools for investigating embryonic development, gene expression and tissue differentiation. In avian species, injection of DNA into oocytes has been used to generate transgenic chickens but this technique is very laborious and has a low yield of transgenic animals. Establishing a system of genetically engineered embryonic stem cells will provide a new efficient tool for exploring various combinations of genomic manipulations and their effects on developmental processes in the chicken model. Previous work on chicken embryonic stem cells has established a method of harvesting and growing chicken embryonic stem cells, but integration of chicken embryonic stem cells into a live chick embryo has yet to be accomplished.

Mammalian embryonic stem cells have been successfully xenografted into chicken embryos. However, these studies addressed the question of embryonic stem cell differentiation into a tissue that has already been formed in the embryo while no studies concerning the grafting of undifferentiated embryonic stem cells into an undeveloped tissue in the chick embryo have been performed.

In order to examine the entire developmental process of a specific tissue it is crucial to study its formation from the moment that the tissue’s precursors are first determined. To do so, labeled embryonic stem cells must be grafted into the embryo during early developmental stages into the specific area that will give rise to the tissue’s precursor cells.

Fluorescently labeled mouse embryonic stem cells provide a valuable tool for examining their ability to integrate in-vivo into the developing embryo using live imaging. In order to study the integration and differentiation of embryonic stem cells into a specific tissue, the nephric duct, which is a migrating structure, was chosen. The nephric duct is the collecting duct of the kidney that transports the kidney’s processed filtrate to the outside. During the nephric duct’s formation, the nephric duct precursor cells migrate posteriorly while constructing the duct along the anterior-posterior axis.

In the current study, fluorescently-labeled mouse embryonic stem cells were transplanted into the nephric duct precursor region of gastrula stage chick embryos. Mouse embryonic stem cells integrated into the chick nephric duct, expressing the duct marker PAX2, and participating in the duct migration process. 

Ultimately, we hope that this work will set the stage for future studies of tissue development using xenografted mouse embryonic stem cells and grafting of genetically manipulated chicken embryonic stem cells to test its effects on tissue development.