Le foie a des capacités de régénérations importantes qui lui permettent de reconstituer progressivement sa masse cellulaire suite à une agression. L’induction d’une régénération hépatique est une approche qui a été utilisée dans de nombreux modèles animaux afin de favoriser la prise de greffe hépatocytaire pour le traitement des maladies métaboliques héréditaires hépatiques (MMHH). Par ailleurs, les capacités de régénération du foie sont utilisées en pratique clinique courante dans le cadre de la chirurgie hépatique afin de préparer le foie à une hépatectomie majeure. Les principaux objectifs de ce travail ont été d’étudier des moyens peu invasifs pour induire une importante régénération hépatique dans deux buts précis : i) favoriser la transplantation d’hépatocytes thérapeutiques pour le traitement des MMHH ; ii) élargir les possibilités de prise en charge des patients nécessitant une hépatectomie.Dans un premier temps, nous avons évalué l’effet d’une embolisation portale partielle (EPP) au cours de la transplantation d’hépatocytes dans un des modèles animaux de l’hypercholestérolémie familiale de type IIA, le lapin Watanabe. Dans un deuxième temps, nous avons mis au point chez le rat, une technique d’EPP résorbable répétée visant à entrainer un stimulus répété de régénération hépatocytaire afin d’envisager par la suite l’utilisation de cette technique avant transplantation d’hépatocytes. En parallèle de ces travaux fondamentaux, nous avons évalué en approche clinique l’intérêt de l’EPP résorbable avant hépatectomie majeure. Nos travaux dans le modèle du lapin Watanabe ont montré la faisabilité du protocole, une correction phénotypique in vitro, une amélioration de la prise de greffe hépatocytaire et une expression prolongée du transgène. Notre équipe a développé chez le rat un stimulus additionnel de prolifération hépatocytaire qui permet une augmentation du poids et du volume du foie non embolisé en comparaison à une seule EPP résorbable. Enfin, dans une série rétrospective préliminaire, la technique d’EPP résorbable a été utilisée avant hépatectomie majeure. L’approche a été bien tolérée chez tous les patients et a permis de systématiquement envisager la chirurgie.L’EPP résorbable est une technique peu invasive capable d’induire une régénérative hépatique efficace. Cette approche pourrait permettre notamment d’augmenter les capacités de proliférations hépatiques par la répétition du stimulus d’embolisation. A terme, l’EPP résorbable répétée pourrait permettre de modeler à la demande l’organisation du volume hépatique favorisant ainsi l’hypertrophie de tel ou tel secteur en fonction des besoins. / The liver has an important regenerative capacity allowing progressive reconstitution of the hepatic volume after an aggression. The induction of liver regeneration was used in different animal models in order to increase engraftment during hepatocyte transplantation for the treatment of inherited metabolic liver diseases (IMLD). Furthermore, liver regenerative capacities are used in routine clinical practice before liver surgery in order to prepare the liver for major hepatectomy.The main objective of this doctoral thesis was to evaluate minimally invasive approaches inducing substantial liver regeneration, focusing in two specific aims: i) increasing the engraftment of therapeutic cells for the treatment of IMLD; ii) expanding the therapeutic options for patients requiring an hepatectomy In a first study, we evaluated the impact of a partial portal vein embolization (PVE) during hepatocyte transplantation in the animal model of familial hypercholesterolemia type IIA, the Watanabe rabbit. In a second investigation, we developed an approach of repeated reversible PVE in a rat model to further boost liver hypertrophy, planning to apply this approach in hepatocyte transplantation. In parallel, we evaluated the clinical interest of reversible PVE before major hepatectomy.Our results of PVE during hepatocyte transplantation in the Watanabe rabbit model demonstrated the feasibility of the procedure, in vivo phenotypic correction, increase of liver cell engraftment and stable transgene expression. Our team developed in the rat an additional stimulus of hepatocyte proliferation allowing increase of non-embolized liver lobe weight and volume in comparison to a single reversible PVE. Finally, the reversible PVE approach was evaluated before major hepatectomy in a preliminary retrospective series of 20 patients. The procedure was well tolerated and allowed to plan surgery in all patients.Reversible PVE is a minimally invasive technique allowing to successfully induce liver regeneration. This approach could increase hepatocyte proliferation capacity by using an additional stimulus of repeated embolization. In the future, reversible PVE may allow on demand modeling of liver volumes organization by supporting the hypertrophy of a specific liver lobe when required.

La régénération hépatique après résection hépatique majeure ne se fait pas toujours de la même façon et une partie importante des facteurs déterminants de la régénération pourrait être liée aux constantes hémodynamiques hépatiques.Le but de nos travaux a été d'étudier cette relation en se basant notamment sur les modèles expérimentaux d'hépatectomie chez le gros animal. Nous avons étudié la régénération sur forme de volume mesuré en imagerie, examen anatomopathologique, prolifération des hépatocytes et des vaisseaux dans le parenchyme hépatique jusqu'à une reconstruction 3D du lobule hépatique.Nos résultats indiquent des liens forts entre l'hémodynamique et la qualité de la régénération et laissent entrevoir la possibilité d'agir sur les composantes hémodynamique. / Liver regeneration after liver resection does not occur in the same way in different conditions. A major determining factor of the regeneration could be the hemodynamic environment of the regenerating liver.The aim of our work was to study the relationship between liver regeneration and hemodynamic parameters, based mainly on experimental models of liver resection in large animals. We studied regeneration as CT scan volume, histopathology, hepatocyte proliferation and vessel neoformation inside the liver parenchyma, up to 3D reconstruction of the liver lobule.Our results show important relationships between liver hemodynamics and liver regeneration and let imagine the possibility to modulate hemodynamic parameters in order to modify liver regeneration.

Partial hepatectomy (PH) is a treatment of choice for patients suffering from early stage hepatocellular carcinoma (HCC). Ablation of large proportion of the liver is rendered possible because of the ability of the liver to regenerate. Yet, a significant number of patients will experience recursion of the disease. Such relapses are unfortunately rather frequent and constitute a bad prognosis. The development of new strategies aiming at reducing the risk of recursion of HCC is thus a paramount element of the surgery-based treatment. Some previous studies have proposed that the regenerative process as well as the fate of the immune cells during the liver regeneration process is linked to this recurrence phenomenon.In this study, we investigated the impact of PH on HCC development in a pre-clinical murine model. We implanted Hepa1-6 hepatocarcinoma cells (a murine hepatocarcinoma cell line) directly in the liver of mice and compared a non-resected group with a group undergoing 40% PH one week following tumor implantation. Analysis were relying on bioluminescence imaging and flow cytometry. We demonstrated that liver regeneration increases tumoral proliferation. This proliferation was associated with a reduction in the number of liver resident macrophages, i.e. Kupffer cells (KC). KC anti-tumoral activity was also proved using conditional ablation model. We further studied the mechanisms leading to this disappearance and demonstrated that, under normal regeneration conditions, PH-induced KC number reduction was dependent on tumor necrosis factor-α (TNF-α), receptor interacting protein kinase (RIPK) 3 and caspase-8 activation whereas interleukin (IL)-6 acted as a KC pro- survival signal. In mice with previous Hepa 1-6 encounter, the KC reduction changed toward a TNF-α-RIPK3-caspase-1 activation. This data suggest a switch from apoptosis to pyroptosis induction in KC following PH. Moreover, KC disappearance associated with caspase-1 activity induced the recruitment of monocyte derived cells that are beneficial for tumor growth while caspase-8 dependent reduction did not, underlying the importance of macrophages activated death-pathway in regulating the anti-tumoral immune response. Our results show the necessity for comprehensive multidisciplinary treatment approach following PH and propose new targets in order to reduce the relapse of the disease occurring after surgery. / Doctorat en Sciences biomédicales et pharmaceutiques (Médecine) / info:eu-repo/semantics/nonPublished

Indiana University-Purdue University Indianapolis (IUPUI) / CXXC finger protein 1 (CFP1) is an epigenetic regulator of H3K4 and cytosine methylation. Due to its role in establishing and maintaining methylation patterns, CFP1 determines whether DNA is found in its euchromatin or heterochromatin state and as such whether genes are transcriptionally active or inactive. In stem cells, deficiency of CFP1 results in inability to differentiate and in murine embryos it results in periimplantation death. Despite the demonstrated importance in developing tissue, the role of CFP1 in mature tissues, such as the liver, has yet to be elucidated. This study examined the role of CFP1 in maintaining liver homeostasis under conditions involving hepatocellular stress by examining liver regeneration, pregnancy-induced hepatomegaly, and non-alcoholic steatohepatitis (NASH) disease progression. The liver’s ability to recover was analyzed through liver:body mass ratios, blood serum analysis, liver histology, and qualitative observations. Deficiency of CFP1 in the livers of animals subjected to partial hepatectomies (PH) resulted in decreased liver regeneration capacity with liver mass restoration becoming significantly different starting at 48H post-PH and remaining so until 10D post-PH. This decreased regeneration appeared to be the result of reduced hepatocyte mitosis. Mouse dams lacking hepatic CFP1 mated with males expressing CFP1 displayed a proclivity for dystocia. Mice subjected to a fast food diet resulting in NASH while lacking hepatic CFP1 experienced decreased weight gain and hepatic lipid accumulation compared to their CFP1 expressing counterparts. Through these three studies, the critical role of CFP1 for the maintenance of liver homeostasis was demonstrated.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20219号 / 医博第4178号 / 新制||医||1019(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 小西 靖彦, 教授 小池 薫, 教授 坂井 義治 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20280号 / 医博第4239号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 川口 義弥, 教授 羽賀 博典, 教授 坂井 義治 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21644号 / 医博第4450号 / 新制||医||1034(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 小西 靖彦, 教授 伊達 洋至, 教授 川口 義弥 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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Introduction: The reason for the inability of performing the liver resection for colorectal carcinoma metastasis is usually insufficient remnant liver parenchyma after liver resection (future liver remnant volume - FLRV). The current standard method of increasing FLRV is the embolization of the branch of portal vein (portal vein embolization - PVE) on the side of the tumor, and then suspended after hypertrophy of the non-embolised lobe liver resection. Unfortunately, there are some patients who do not increase liver volume despite perfectly executed PVE. Besides that, FLRV occurs during the time necessary for hypertrophy progression of metastatic disease. Therefore, we are trying to find the appropriate way to encourage the growth of remaining liver parenchyma and accelerate hypertrophy of the contralateral liver lobe. From our previous experience (IGA MZ NS 10240), it is possible to be optimistic that there hope is the way of hematopoietic progenitor cells (HPC - adult stem cells) after previous PVE to non-embolised branches of the portal vein. These cells do not only accelerate liver regeneration, but are also able to improve its function (function of the liver) which is especially important for patients after neoadjuvant chemotherapy (steatohepatitis or steatofibrosis), and for patients with...

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