Stem cells play a vital role in the turn over of permanently self-renewing tissues (e.g. corneal epithelium, epidermis, bone marrow). Stratified cornea epithelia serve, as ideal tissue models for studying ???stemness???, as the site of cells in the different stages of differentiation are anatomically easily identifiable. Studies targeting limbal stem cell maintenance, in-vitro gene expression during storage and differentiation will benefit future therapeutic applications (e.g. corneal transplantation). Knowledge of stem cell behaviour will help explain the pathophysiology of corneal related ocular surface disorders (e.g. idiopathic limbal stem cell deficiency, pterygium and limbal dermoids), establish new treatment modalities (e.g. allogenic cellular transplants) and help promote invivo expansion of residual stem cell populations in deficiency states. The major obstacle in the progress of research on limbal stem cells is the lack of knowledge of phenotypic markers of limbal epithelial stem cells. This project first studied the limbal expression of phenotypic markers that were discovered in other human adult and embryonic stem cell populations using microarray differential expression studies. Gene expression profiles of the relatively primitive human foetal limbus were compared with that of the central cornea. Microarray was also performed to identify the differential gene expression profile of cultured primary human limbal epithelial cells, when compared to the limbal epithelial cell population isolated after 5 serial cultures. 33 genes were upregulated in the human foetal limbus and primary cultured human limbal epithelium, when compared respectively to the central foetal cornea (first experiment) and the limbal epithelial cell population after the 5th trypsin passaged culture (second experiment). Four foetal limbal and primary limbal epithelial upregulated genes (CK15, CK14, Cdh3, and Wnt4) were confirmed to be upregulated by semi quantitative RT-PCR and immunohistochemical experiments on the human foetal cornea, adult human cadaveric cornea and cultured human limbal epithelial cells. The microarray defined phenotypic profile of both the foetal limbus and cultured adult limbal epithelial cells will help identify these cells in in-vitro and in-vivo states. The expression of these 4 selected markers in the limbal dermoid and pterygium suggests that limbal epithelial cells containing a stem cell population are involved in the pathogenesis of these two disorders.

A five stage selection protocol originally applied to mouse embryonic stem cells (mESCs) was examined for the derivation of insulin producing cells from human embryonic stem cells (hESCs). Insulin gene expression was observed and insulin protein was measured by radioimmunoassay. However, the radioimmunoassay results were shown to be susceptible to false positive findings due to the presence of exogenous insulin within differentiation media and it was concluded that this particular strategy was not ideal for the derivation of insulin producing cells from hESCs. An investigation was then undertaken regarding the in vivo differentiation of cells derived from hESCs seeded within 3D scaffolds to determine if this would result in the derivation of insulin producing cells. Within scaffolds there were abundant cells which stained positively for ectoderm lineage markers including nestin. Cells which stained positively for markers of endothelial progenitors representing the mesoderm lineage were also observed and rare cells stained for endoderm markers including insulin. These investigations also demonstrated that transplanting scaffolds seeded with cells derived from hESCs between the liver lobules of immunodeficient mice could lead to the formation of teratomas. Factors that may have influence the formation of teratomas were further investigated and it was demonstrated that teratoma formation was inhibited by altering in vitro treatment of cells. An in vitro investigation was then performed to determine the extracellular matrix (ECM) producing capacity of hESCs and differentiated cells derived from hESCs because ECM proteins are required for the formation of 3D structures similar to pancreatic islets. The results from this investigation indicated that differentiated cells produced multiple ECM proteins at substantially higher levels than hESCs. The ECM producing differentiated cells could be useful in the development of surrogate islet like tissue by supplying a suitable ECM structure within a 3D scaffold environment to aid the function of ??-cell surrogates. Furthermore, these differentiated cells derived from hESCs were shown to produce an adhesive basement membrane in vitro, which is derived from human sources, and could be utilized in the derivation, propagation and differentiation of hESCs.

Introduction: Around a quarter of patients with spinal cord injury develop post traumatic syringomyelia (PTS), causing progressive neurological deficits. Current surgical treatment is unsatisfactory. Endogenous stem cell therapy, aiming at replacing lost tissue and repairing damaged ones by endogenous progenitors, may offer hope. Investigation into the reaction of endogenous progenitors in PTS may extend our knowledge about stem cell biology and help to develop a new treatment option for PTS. Endogenous stem cells were found to differentiate into astrocytes. Reactive astrocytes and gliosis are shown to have an important role in spinal cord injury, such as protecting neurons, limiting inflammation and regulating local environment to suit progenitors. We hypothesize that reactive astrocytes may play an important protective and potential therapeutic roles in PTS. The aim of this thesis is to study proliferation, differentition and location of endogenous progenitors and their roles in PTS. Materials and methods: Excitotoxic injury model of PTS was performed in adult Wistar rats. Proliferating cells were marked by either exogenous mitotic marker bromodeoxyuridine or endogenous mitotic marker Ki67.lmmunofluorescence techniques targeting mitotic markers were used to trace the proliferating cells. Immunofluorescent double staining techniques were used to phenotype the proliferating cells. Results: A large number of endogenous progenitors appear in PTS from 24 hours to at least 8 weeks post injury (PI). They proliferate much faster in PTS than in the control animals. Although less endogenous progenitors are observed after 4 weeks PI, their number is still much higher than that in the control animals. Immediately after injury, progenitors exist mainly in the white matter, but the majority of them shift their position closer to the lesion within 2 days. In the chronic stage, the majority of stem cells are located in and around the lesion site. Endogenous progenitors differentiate into astrocytes but not oligodendrocytes or neurons within 8 weeks. Astrocytes respond to injury by upgrading GFAP (1 day PI), becoming hypertrophic (7 days PI) and forming glial scar (2 weeks PI) in PTS. The development of a glial scar corresponds with the stage of cyst stability or reduction in size. Conclusions: Endogenous progenitors exist in PTS and they respond to injury by proliferating and shifting their position towards the lesion. These studies are important in understanding the endogenous stem cell response to PTS and lay the groundwork for future studies examining stem cell therapy for the condition. Endogenous progenitors in the PTS model differentiate into astrocytes, which help to form the glial scar lining the syrinx. Reactive gliosis may play an important role to seclude the injury site from healthy tissue, prevent a cascading wave of uncontrolled tissue damage and restrict the syrinx enlargement.

Includes bibliographies. / xi, 127, [90] leaves, [31] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Aims to identify homeobox genes which may have a developmental role during early embryogenesis by the characterization of homeobox gene expression in undifferentiated ES cells, and in a range of differentiated ES cell derivatives. / Thesis (Ph.D.)--University of Adelaide, Dept. of Biochemistry, 1996

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Human adult dental pulp cells (DPSC) reside within the perivascular niche of dental pulp and are thought to originate from migrating cranial neural crest (CNC) cells. During development, CNC cells respond to the environmental cues to migrate and differentiate into the different cell types that contribute to the formation of craniofacial structures and the peripheral nervous system. The Eph family of receptor tyrosine kinases and their ligands, the ephrin molecules, play an essential role in the migration of neural crest cells during development and postnatal stem cell (SC) niche maintenance. "The present study demonstrated multiple Eph receptors expressed primarily on DPSC within the perivascular niche, while the surrounding pulp tissue expressed ephrin-B ligands. EphB/ephrin-B bi-directional signalling inhibited DPSC attachment and spreading, while DPSC migration was restricted through uni-directional ephrin-B1 activated EphB forward signalling in vitro. Furthermore, we observed that ephrin-B was down-regulated in diseased adult teeth compared to paired uninjured controls. Collectively, these studies suggest that EphB/ephrin-B molecules play a role in restricting DPSC attachment and migration in order to maintain DPSC within their SC niche under steady-state conditions. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1274738 / Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2007

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 6 uppsatser.

Thesis (Ph. D.)--University of Adelaide, Dept. of Biochemistry, 1996. / Includes bibliographical references.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (Ph.D.)--University of Calgary (Canada), 2005. / Includes bibliographical references.