Characterisation of the conditioned media produced by the visceral endoderm-like cell lines : towards a defined medium for the osteogenic differentiation of embryonic stem cells

• Main Author: Kang, Yunyi
• Published: Imperial College London 2008
• Subjects: 616.02774
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501283

Destruction of bone tissues due to related diseases and developmental defects in skeletal tissues can cause severe pain and mobility problems in daily life. One way to address the clinical needs of these bone-related diseases is to restore or replace the function of bone tissues using tissue engineering approaches. Embryonic stem cells (ESCs) have recently emerged as a potentially suitable cell source for skeletal tissue engineering applications due to their unique developmental and self renewal potential. However, despite the considerable progress made in directing ESC differentiation to therapeutically useful lineages, key challenges still remain, particularly in improving differentiation efficiency and achieving a homogeneous population of the desired cell type. The overall aim of this thesis is to work towards the generation of a defined medium for the enhanced skeletal lineage differentiation of ESCs, which could be used for 11 potential therapeutic applications. In order to accomplish this aim, the osteogenic-inducing effects of media obtained from visceral endoderm (VE)-like cell lines (HepG2 and END2 cells) were investigated and subsequently were characterised using proteomics. In embryogenesis, VE plays an important role as a source of signals which instruct adjacent cells to differentiate. Therefore, it is hypothesised that the soluble factors produced by VE-like cell lines might act as important signals during ESC differentiation. Experimental results showed that the conditioned media (CM) by the VE-like cell lines enhanced the osteogenic differentiation of murine ESCs. The proteins present in the CM were identified and certain ones were investigated for their inductive activities, as observed in the CM. It was established that fibronectin was involved in the stimulatory effect of the CM, thereby demonstrating its potential applicability in development of a defined medium.