Ahmad, Mohson (2004) Umbilical cord blood multi-tissue differentiation. (MSc(R) thesis), Kingston University, .

Abstract

Significant therapeutic applications to date have been achieved through the use of haemopoietic/progenitor cells (HSPC). Cancer patients receiving high-dose radioc-chemotherapy no longer suffer from extreme levels of neutropenia due to the administration of stimulating grwoth factors. The extent of HSPC for therapeutic potential has yet to be exhausted and the present research aims to expand the mechanisms and methods for further development of this population for future therapeutic use in haematology and in tissue engineering from conventional, ethically approved blood sources. UCB is enriched with early stem cells (SC) but this enrichment is relative to the volume available thus limiting its use in direct replacement therapies. One of the first objectives of this work was to test the in vitro expansion of CD133+ sten cells by a novel embryological derived growth factor set (arbitrarily named SFX), which revealed dose-response activity over many weeks. A population of UCB mononucleated cells maintained cell expansion over 4 weeks from SFX stimulation. The CD133+ cell population also harvested from UCB maintained intense cell proliferation continuing beyond 4 weeks. The above populations both displayed amplified responses at increasing concentrations of SFX. Stem cells have been reported to be present around the body in a quiescent state. A second objective was to establish whether trauma to human cells released stromal-derived-factor-1 (SDF-1) implicated in attracting SCs to the site of injury and important if UCB SCs are to find, post-transplant suitable sites for repair. Three cells lines were cultured; two neural and one hepatic. Before the addition of trauma agents the hepatic cell line model displayed highest natural release of SDF-1 but the neural cell line models induced a higher release of SDF-1 upon exposure to cellular stressors. Its release is confirmed upon trauma and perhaps suggests stem cells homing activity, maybe a natural feedback response initiating tissue repair? SCs with the correct combination of growth factors, have shown multi-tissue differentiation. The final objective of this study was to optimise this differentiation using collagen based scaffolds, recreating a more normal "in vivo" condition, for hepatocyte development as a model test system. Within one week significant congestive growth of the hepatocyte cells within the scaffolds 'resembling' tissue structre was observed. Endothelial tissue was also developed with early peripheral blood CD133+ and CD34+ stem cells harvested with a variety of techniques. The results indicated an amplified response with CD133+ cells. Further work would include characterisation of tissue identity using appropriate markers.

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