Metanephros Transplantation into Adult Recipients: Stem Cells; Cytokines and Physiological Factors

Shannon Armstrong (2008). Metanephros Transplantation into Adult Recipients: Stem Cells; Cytokines and Physiological Factors PhD Thesis, School of Biomedical Sciences, The University of Queensland.

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Author Shannon Armstrong
Thesis Title Metanephros Transplantation into Adult Recipients: Stem Cells; Cytokines and Physiological Factors
School, Centre or Institute School of Biomedical Sciences
Institution The University of Queensland
Publication date 2008-09
Thesis type PhD Thesis
Supervisor Professor Julie H. Campbell
Professor Gordon R. Campbell
Professor Melissa H. Little
Total pages 287
Total colour pages 30
Total black and white pages 257
Subjects 320000 Medical and Health Sciences
Abstract/Summary Chronic kidney disease often progresses to end stage renal disease (ESRD), which is inevitably fatal, with more than a million deaths worldwide each year. There is no cure for ESRD and treatment is aimed at augmenting function via dialysis (haemodialysis or peritoneal), or replacing organs through kidney transplantation from a suitable human donor. Both are less than satisfactory, and alternative treatments are continually being investigated such as bioartificial kidneys - composed of a conventional filter and proximal tubule cells seeded onto hollow fibre membranes, and xenotransplantation. However, neither of these options is able to fully mimic a native, healthy kidney, and is therefore not a permanent solution. The current project examines cellular therapeutic options for renal repair and regeneration through the use of metanephros (embryonic kidney) transplantation into adult recipients. In particular, it investigates the effect of physiological factors, as well as growth factors and stem cells, on metanephros growth, vascularisation and development. Firstly, the effect of recipient pregnancy on developmental success was examined. Metanephroi at embryonic age (E) 12.5 and E15.5 were transplanted onto the internal lateral abdominal wall of either unilaterally nephrectomised, 12.5 days post coitum (d.p.c.) pregnant, or control (non-pregnant, non-unilaterally nephrectomised) recipients for 7 days. Onward development of E12.5 metanephroi occurred within both pregnant and unilaterally nephrectomised recipients, however only pregnancy permitted the maturation of glomeruli in later stage E15.5 metanephroi, thus implying pregnancy provides an environment conducive to continued organogenesis. The effect on development of transplanted metanephroi exposed to exogenous growth factors prior to transplantation was next investigated. E12.5, E13.5 and E15.5 metanephroi from C57/Bl6 mice were soaked for 1 hour in an exogenous growth factor then transplanted for 7 or 14 days into the peritoneal cavity of C57/Bl6 adult recipients. Glial Cell Line-derived Neurotrophic Factor (GDNF) was particularly successful with significantly more S-shaped bodies and glomeruli after both 7 and 14 days transplantation, and greater volumes compared with control. It was observed in the above study that GDNF-exposed metanephroi exhibited aberrant branching of the ureter around the harvested grafts. During embryonic development the region caudal ureteric duct invades the bladder to connect the developing kidney. The ability of GDNF to induce the embryonic ureter to invade the recipient bladder, thus recapitulate development, to provide a direct conduit between the implanted metanephros and the recipient bladder was then investigated. Connecting ureter-like tubes were observed in 71% of GDNF-exposed transplants. The tubes exhibited ureter-like morphology and contained a muscular layer indicating possible functionality. A further mechanism by which metanephros development may be enhanced in the adult recipient is increasing the progenitor compartment prior to transplantation. In order to accomplish this, metanephroi must be cultured such that they are transferable to the adult recipient after a period of incubation. To this end, the hanging drop method of tissue culture was investigated for its ability to support renal development. It was determined that metanephroi can successfully be incubated in for 4-5 days in hanging drops. Additionally, it was shown that exogenous mesenchymal stem cells can incorporate into cultured metanephroi and contribute to developing renal structures. Whilst the option of xenotransplantation has been pursued to relieve the shortage of donor number for transplantation, the best option would be to prevent the deterioration of renal function through manipulation of an endogenous renal stem/progenitor pool to effect renal repair and regeneration. To determine if a renal stem/progenitor cell exists, mice were labelled with BrdU and allowed to dilute out over 60 weeks to elucidate the location of Label Retaining Cells - putative stem cells. It was shown that putative renal progenitor cells exist in every region of the kidney. It was also shown that these cells exhibit the stem cell surface marker Sca-2. In summary, this thesis has shown that metanephros transplantation can be enhanced through manipulation of recipient physiology and exogenous growth factors, in particular GDNF, to improve the size and differentiation of the developing kidney. The development of a patent ureter-like connection between the recipient bladder and implanted metanephros, along with enhanced intra-renal vascularisation, imparts realistic potential to the development of supernumerary kidneys to increase organ function in the renal failure setting.
Keyword Kidney
metanephros transplantation
Label Retaining Cell
hanging drop
Additional Notes COLOUR PAGES: 26, 29, 30, 79, 85, 91, 103, 123, 126, 153, 157, 159, 161, 165, 169, 181, 183, 187, 191, 195, 199, 221, 245, 246, 247, 251, 253, 255, 259, 261,

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Created: Wed, 22 Apr 2009, 13:31:02 EST by Miss Shannon Armstrong on behalf of Library - Information Access Service