2007 Winter Meeting - London - The Pathological Society of Great ...

PL5Modelling the expansion of mutated clones within humancolonic crypts and their migration through the colon{P} SAC McDonald 1 , P. Tadrous, M Bjerknes 5 , M Deheragoda 2 ,SJ Leedham 2 , M Rodriguez-Justo 3 , L Greaves 4 , G Elia 2 ,M Novelli 3 , DM Turnbull 4 , JAZ Jankowski 1 ,NA Wright 61 Oxford University, Oxford, United Kingdom, 2 Cancer Research UK,London, United Kingdom, 3 University College Hospitals London, London,United Kingdom, 4 University of Newcastle upon Tyne, Newcastle, UnitedKingdom, 5 University of Toronto, Toronto, Canada, 6 Barts and the LondonSchool of Medicine and Dentistry, London, United KingdomRecent data from our laboratory has shown that mitochondrial DNA (mtDNA)mutations can spread through the human colon by a process of crypt fission,where one crypt is able to divide into two daughters(Proc. Natl. Acad. Sci.103:714-19).Here we show how such mutated cells expand through the human colonic cryptby 3D modelling from serial sections throughout single crypts. This highlightsthat cellular migration within crypts is more complex than originally thoughtand gives insights into actual stem cell location.Furthermore, the rate at which normal human crypts undergo fission isunknown. Bjerknes (J. Theor. Biol. 179:381-5) developed a mathematicalmodel by which he calculated the rate at which crypts within aberrant crypt fociwere able to expand. This predicts that if an aberrant crypt population wasexpanding at the same rate as normal crypts then the number of single aberrantcrypts should be half of the number of those within foci.Here we use this model to show that crypts deficient in mitochondrialcytochrome c oxidase (CoxSU1) expand at the same rate as those with normalCoxSU1 expression. We have counted the total number of deficient cryptswithin tissue sections stained with CoXSU1 from normal colons of 35 patients.1298 deficient crypts were observed of which 597 were single. This gives aratio of singletons to patches of 0.46 which are expanding only at 1.15 timesfaster than positive crypts.These data suggest that crypts with or without mtDNA mutations expand at thesame rate and that this is an appropriate model to calculate the crypt fission rateof the human colon.PL6Mitochondrial DNA Mutations to Investigate Cell LineageRelations in Human Liver{P} TG Fellous, M Brittan, L Mears, S Bhattacharya, H Kocher,MR AlisonInstitute of Cell and Molecular Science, QMUL, London, United KingdomCurrent research on human liver regeneration and stem/progenitor cell biologyis hampered by lack of a clonal marker. It is now clear that mitochondrial (mt)DNA mutations occur in human liver stem and progenitor cells, and that thesemutations have much potential as a stem cell marker for looking at both theexpansion of mutated clones in the liver and for providing a platform forlineage analysis in humans for really the first time. Studying cells withmutations in the cytochrome c oxidase gene (as a cell lineage marker), largelyencoded by mtDNA, has revealed patches of COX -ve cells in liver, which arefrequently in close proximity to the portal tract and are present in serial sectionsat least 330µm deep into the tissue. This suggests that clonogenic cells in thenormal human liver may proliferate en masse from a common niche close to theportal tract. This study highlights a novel means of tracing patterns of celldivision and migration in human liver that can be used to study changes in cellbehaviour during hepatitis, cirrhosis and neoplasia.Winter Meeting (191 st ) 3–5 January 2007 Scientific Programme25