Studies of Human and Porcine Hepatocyte Cryopreservation and Their Suitability for Use in Bioartificial Liver Development

Abstract: The aim of this thesis was to assess feasibility of using chronically injured liver as a source for hepatocyte isolation, to compare inter-laboratory variability, to establish an efficient method for hepatocyte isolation and cryopreservation and to review whether anti-apoptotic compounds have any effect on cryopreservation outcomes. Method: A two-stage isolation protocol was used, with multiple washes and centrifugation compared with Percoll® purification pre- and post-cryopreservation and pre-incubation. A new cryopreservation media was validated and cells cryopreserved using this with the addition of potential anti-apoptotic agents. Demographic details were collected prospectively and histological samples collected where possible for analysis. Hepatocyte viability, yield per gram, hepatocyte loss, monolayer protein, visual attachment, phase I and II enzyme activity and measures of apoptosis were assessed. Results: Between October 2003-2005, 83 individuals donated tissue to UKHTB, with an additional 140 donors from elsewhere. 175 hepatocyte isolations were performed yielding more than 50 billion cells. Fresh cell culture was universally successful although purification led to significant cell loss. This was exacerbated during cryopreservation with especially poor porcine hepatocytes. None of the adjuncts to improved isolation or cryopreservation demonstrated reproducible improvement in outcome. There was only a weak negative correlation between histological injury and isolation outcome. Normothermic resuscitation prior to isolation conferred benefit across almost all measurable outcomes. Conclusion: There is significant inter-donor variability with regard to the outcomes of hepatocyte isolation and all purification methods cause unacceptable hepatocyte loss. A viable cell will attach and function and this is essential for many of the studies that are subsequently performed. Organs which are turned down for transplantation could be used for hepatocyte isolation

Health burdens of surface ozone in the UK for a range of future scenarios

Exposure to surface ozone (O3), which is influenced by emissions of precursor chemical species, meteorology and population distribution, is associated with excess mortality and respiratory morbidity. In this study, the EMEP-WRF atmospheric chemistry transport model was used to simulate surface O3 concentrations at 5 km horizontal resolution over the British Isles for a baseline year of 2003, for three anthropogenic emissions scenarios for 2030, and for a + 5 °C increase in air temperature on the 2003 baseline. Deaths brought forward and hospitalisation burdens for 12 UK regions were calculated from population-weighted daily maximum 8-hour O3. The magnitude of changes in annual mean surface O3 over the UK for + 5 °C temperature (+ 1.0 to + 1.5 ppbv, depending on region) was comparable to those due to inter-annual meteorological variability (− 1.5 to + 1.5 ppbv) but considerably less than changes due to precursor emissions changes by 2030 (− 3.0 to + 3.5 ppbv, depending on scenario and region). Including population changes in 2030, both the ‘current legislation’ and ‘maximum feasible reduction’ scenarios yield greater O3-attributable health burdens than the ‘high’ emission scenario: + 28%, + 22%, and + 16%, respectively, above 2003 baseline deaths brought forward (11,500) and respiratory hospital admissions (30,700), using O3 exposure over the full year and no threshold for health effects. The health burdens are greatest under the ‘current legislation’ scenario because O3 concentrations increase as a result of both increases in background O3 concentration and decreases in UK NOx emissions. For the + 5 °C scenario, and no threshold (and not including population increases), total UK health burden increases by 500 premature deaths (4%) relative to the 2003 baseline. If a 35 ppbv threshold for O3 effects is assumed, health burdens are more sensitive to the current legislation and + 5 °C scenarios, although total health burdens are roughly an order of magnitude lower. In all scenarios, the assumption of a threshold increases the proportion of health burden in the south and east of the UK compared with the no threshold assumption. The study highlights that the total, and geographically-apportioned, O3-attributable health burdens in the UK are highly sensitive to the future trends of hemispheric, regional and local emissions of O3 precursors, and to the assumption of a threshold for O3 effect

Probabilistic spatial risk assessment of heat impacts and adaptations for London

High temperatures and heatwaves can cause large societal impacts by increasing health risks, mortality rates, and personal discomfort. These impacts are exacerbated in cities because of the Urban Heat Island (UHI) effect, and the high and increasing concentrations of people, assets and economic activities. Risks from high temperatures are now widely recognised but motivation and implementation of proportionate policy responses is inhibited by inadequate quantification of the benefits of adaptation options, and associated uncertainties. This study utilises high spatial resolution probabilistic projections of urban temperatures along with projections of demographic change, to provide a probabilistic risk assessment of heat impacts on urban society. The study focuses on Greater London and the surrounding region, assessing mortality risk, thermal discomfort in residential buildings, and adaptation options within an integrated framework. Climate change is projected to increase future heat-related mortality and residential discomfort. However, adjusting the temperature response function by 1–2 °C, to simulate adaptation and acclimatisation, reduced annual heat related mortality by 32–69 % across the scenarios tested, relative to a no adaptation scenario. Similar benefits of adaptation were seen for residential discomfort. The study also highlights additional benefits in terms of reduced mortality and residential discomfort that mitigating the urban heat island, by reducing albedo and anthropogenic heat emissions, could have