AbstractsBiology & Animal Science

Embryonic stem cells (ESCs) are pluripotent cells capable of indefinite self renewal in vitro while maintaining the ability to differentiate into cell types of all three germ layers. ESCs are outstanding options of in vitro cell models for regenerative medicine, functional genomics, human developmental biology and drug discovery study. Stem cell research is among the most promising fields of biotechnology, and which provides the potential of developing novel approaches to repair or replace damaged tissues and cells. The present day, exponentially growing effort of stem cell research emphasizes a major need for convergence of more efficient and appropriate laboratory technologies to sustain the growth, proliferation and differentiation potential of stem cells. Although so far, a variety of conventional bioreactors with different configurations (such as spinner flasks, rotary, perfusion bioreactor, etc.) have been designed and adapted for stem cell expansion and differentiation, bioreactors can be disadvantageous in bench-top research because they need large space, consume huge amount of reagents and need more time to operate and maintain (sterilizing, cleaning, assembling, and disassembling of the bioreactor components). The requirements for costly equipment and generating shear stress due to the fluid flow, and the lack of physical similarity between microenvironments of bioreactor and actual cell microenvironment, make using bioreactors undesirable. In tissue engineering, micro-scale technology is an approach that combines micro-techniques with materials science and surface engineering, and results in a profound exploration of the microenvironment where cells are embedded. These technologies are able to address some of the limitations imposed by conventional tissue engineering methods. Indeed, developing successful novel small-scale technologies for in vitro cultivation of different types of cells can assist in increasing our knowledge on conditions that control stem cell growth and differentiation and organ development. In fact, small scale bioreactors are miniaturized versions of conventional bioreactors, where high- throughput cell based assays can be carried out at low cost compared with their macro-scale counter- parts. The first aim of this thesis was to develop a disposable miniaturized bioreactor through a novel and inexpensive method for effective stem cell proliferation. To this end, an effective surface functionalization method was developed for enhancing the biocompatibility of a PDMS surface that is protein resistant while facilitating cell proliferation (expansion) and maintaining the pluripotency potential of cells. The micro-bioreactor was fabricated in the form of a fixed bed bioreactor with a microchannel reactor bed. The microchannel was functionalized to enable cell adhesion and resistance to protein adsorption. The functionalized surface was found to be biocompatible with cancer and embryonic stem cells (ESCs), and while facilitating cell proliferation. Differentiation of ESCs into a variety of…