The Parametric Studies of Human Fetal Mesenchymal Stem Cells in Bi-axial Bioreactors

Abstract

Successful bone tissue engineering strategy relies on robust cell culturing technique as well as profitable cellular microenvironment. For the current clinical treatment, the expansion of cells in vitro has been a promising alternative method for the bone tissue engineering strategy. In order to enhance the culture efficiency, bioreactor systems are widely researched for the different clinical purposes. Currently, rotating wall bioreactors, biaxial bioreactors, perfusion bioreactors and spinner flask systems should be widely used in the experiments and each of them should has its own advantages and disadvanges. In this project, I would like to achieve the enhanced efficiency of human fetal mesenchymal stem cells (hfMSCs) by the parametric studies in biaxial bioreactor systems for the bone tissue engineering. The hypothesis include: 1). the osteogenesis of hfMSCs can be improved by mechano-induction effect; 2) chemical stimulation can safely enhance the proliferation and differentiation of hfMSCs; and 3) for the bioreactors application, cell seeding method can play a significant role supporting the progress of the in vitro cell culture.

First, I investigated the mechanical stimulation effect on the bone tissue scaffolds. During humans? daily activities, the human skeletal system may sustain different kinds of forces and majority of them should be multiaxial and cyclical. This is important for improving cell proliferation and osteoblastic differentiation. Our aim is to tigger signal transduction pathways and mechanosensitive genes to provide this stimulus on scaffolds in dynamic culture.

Second, effective cell seeding approach is required before the construction of tissue engineered bone graft (TEBG), however, current static cell inoculation technique has been harassed by several limitations, such as the inhomogeneous proliferation and the low efficiency of seeding. Biological glues can provide homogenous cellular distribution as well as improve the ostegenic differentiation of innoculated cells. Therefore, the aim of this study is to investigate the effect of fibrin gule on the human fetal mesenchymal stem cells (hfMSCs), and to prove that this can retain more cells in porous scaffolds and enhance the mineralization. More importantly, this can be applied for in vivo experiments as it can promote specific Extracellular matrix (ECM) proteins.

Third, in the whole system of biaxial bioreactor, especially for the large volume of the culture medium, zinc can be a nutritional element for bone growth retardation. Zinc has also been demonstrated that it can play a physiologic role to stimulate bone protein synthesis, promoting the regulation for bone formation. The experiments aim to show that for the bone tissue engineering, the additional of zinc can increase the differentiation and the proliferation for hfMSCs in vitro study.

Overall, the study for the master programme demonstrated the whole optimization for the existing bioreactor systems. The results of the research showed that mechanical induction and chemical stimulation methods can improve the proliferation and differentiation while cell seeding method can lead to homogenous cell adhesion. These can further the study of the bone tissue bioreactors and might optimize the parameters in growth of bone grafts.