טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentMaria Salameh
SubjectCulturing Human and Mouse Embryonic Stem Cells Using
Microfluidic Bioreactors
DepartmentDepartment of Biomedical Engineering
Supervisor Full Professor Levenberg Shulamit
Full Thesis textFull thesis text - English Version


Abstract

The use of micro-fabricated technologies has been proved to be a useful tool in patterning and culturing cells in micro scale dimensions. 

Microfluidics is an advanced technology associated with the field of lab on a chip.

In the past few years, the use of microfluidic systems has expanded due to their numerous advantages. Their small dimensions produce very low Reynolds number resulting in Laminar flow inside the components, making it possible to maintain parallel streams flowing without mixing which enables the patterning of cell cultures and their environment. Moreover, microfluidic devices utilize minute amounts of reagents making their usage inexpensive and attractive for numerous applications.

It has long been recognized that the microenvironment of cells specifically Embryonic Stem Cells (ESC) is the dominant factor in cell proliferation and differentiation  mechanism.

The main reason that urges scientists to use different micro-fabricated devices for culturing of cells is their ability to control the microenvironment of cells that are grown inside of these components (i.e. they facilitate the monitoring and regulation of the microenvironment in terms of local stresses, local concentration of factors or reagents etc.) when conventional culture methods such as culture dishes do not permit this kind of regulation.

ESC differentiation can be promoted by generation of embryoid bodies (EBs) which are formed either in suspension cultures or using the hanging drop method.

In the present study we have fabricated a new microfluidic device that consists of many micro traps for culturing of EBs. Our goal was to grow the cells under flow imposing a constant size and shape in order to produce uniform EBs. The traps enable producing the aggregates and offer gas and nutrients exchange.

A finite elements simulation was held to demonstrate the velocity streams inside and around the trap. The concentrations of oxygen and nutrients are important factors in micro-devices due to the high surface area to volume ratios, therefore the numerical simulations are needed.

Human and Mouse Embryonic stem cells were cultured inside the micro device and demonstrated extended viability for more than 5 days and differentiation was shown in the inner parts of the EB.

In summary, culturing ESCs inside micro traps enables producing uniform EBs, a tight regulation on their microenvironment and control on their gas and nutrients concentrations.