Project description:Non-alcoholic fatty liver disease (NAFLD), which affects both adults and children, is the most common liver disorder worldwide. NAFLD is characterized by excess fat accumulation in the liver in the absence of significant alcohol use. NAFLD is strongly associated with obesity, insulin resistance, metabolic syndrome, as well as specific genetic polymorphisms. Severe NAFLD cases can further progress to cirrhosis, hepatocellular carcinoma (HCC), or cardiovascular complications. Here, we describe the pathophysiological features and critical genetic variants associated with NAFLD. Recent advances in genome-engineering technology have provided a new opportunity to generate in vitro and in vivo models that reflect the genetic abnormalities of NAFLD. We review the currently developed NAFLD models generated using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) genome editing. We further discuss unique features of CRISPR/Cas9 and Cas9 variants, including base editors and prime editor, that are useful for replicating genetic features specific to NAFLD. We also compare advantages and limitations of currently available methods for delivering genome-editing tools necessary for optimal genome editing. This review should provide helpful guidance for selecting "good fit" genome-editing tools and appropriate gene-delivery methods for the successful development of NAFLD models and clinical therapeutics.
Project description:BackgroundThe complications of Nonalcoholic Fatty Liver Disease (NAFLD) are dependent on the presence of advanced fibrosis. Given the high prevalence of NAFLD in the US, the optimal evaluation of NAFLD likely involves triage by a primary care physician (PCP) with advanced disease managed by gastroenterologists.MethodsWe compared the cost-effectiveness of fibrosis risk-assessment strategies in a cohort of 10,000 simulated American patients with NAFLD performed in either PCP or referral clinics using a decision analytical microsimulation state-transition model. The strategies included use of vibration-controlled transient elastography (VCTE), the NAFLD fibrosis score (NFS), combination testing with NFS and VCTE, and liver biopsy (usual care by a specialist only). NFS and VCTE performance was obtained from a prospective cohort of 164 patients with NAFLD. Outcomes included cost per quality adjusted life year (QALY) and correct classification of fibrosis.ResultsRisk-stratification by the PCP using the NFS alone costs $5,985 per QALY while usual care costs $7,229/QALY. In the microsimulation, at a willingness-to-pay threshold of $100,000, the NFS alone in PCP clinic was the most cost-effective strategy in 94.2% of samples, followed by combination NFS/VCTE in the PCP clinic (5.6%) and usual care in 0.2%. The NFS based strategies yield the best biopsy-correct classification ratios (3.5) while the NFS/VCTE and usual care strategies yield more correct-classifications of advanced fibrosis at the cost of 3 and 37 additional biopsies per classification.ConclusionRisk-stratification of patients with NAFLD primary care clinic is a cost-effective strategy that should be formally explored in clinical practice.
Project description:Genome organization influences transcriptional regulation by facilitating interactions between gene promoters and distal regulatory elements. To analyse distal promoter contacts we used Capture Hi-C (CHi-C) to enrich for promoter-interactions in HiC libraries from mouse ESC and E14.5 fetal liver. Please note additional files included. These files were created using the following protocol: Significantly interacting regions were called using the GOTHiC BioConductor package (http://www.bioconductor.org/packages/devel/bioc/html/GOTHiC.html) as described in (Mifsud et al.).<br>Update on December 2015: the original additional file E-MTAB-2414.additional.1.zip contained an earlier iteration of processed data and not the one that was used for the published paper. The file now contains the correct list of interactions.
Project description:Kupffer cells (KCs) are tissue-resident macrophages which colonize the liver early during embryogenesis. KCs start to acquire a tissue-specific transcriptional signature immediately after colonizing the liver, mature together with the tissue, and adapt to the tissue?s functions. Throughout development and adulthood, KCs have distinct core functions that are essential for liver and organismal homeostasis, such as supporting fetal erythropoiesis as well as postnatal erythrocyte recycling and liver metabolism. However, whether perturbations of macrophage core functions during development contribute to or cause disease at postnatal stages is poorly understood. Here, we utilize a mouse model of maternal obesity to perturb KC functions during gestation. We show that offspring exposed to maternal obesity develop fatty liver disease, driven by aberrant developmental programming of KCs that persists into adulthood. Programmed KCs mediate lipid uptake by hepatocytes through apolipoprotein secretion. KC depletion in neonates born to obese mothers, followed by replenishment with exogenous monocytes, rescues the fatty liver disease. The transcriptional programming of KCs and the fatty liver disease phenotype are also rescued by genetic depletion of hypoxia-inducible factor alpha (Hif1?) in macrophages during gestation. These results establish developmental perturbation of KC functions as a cause for the development of fatty liver disease in adult life and, thereby, place fetal-derived macrophages as intergenerational messengers within the concept of developmental origins of health and diseases.
Project description:Among primates, human neonates have the largest brains but also the highest proportion of body fat. If placental nutrient supply is limited, the fetus faces a dilemma: should resources be allocated to brain growth, or to fat deposition for use as a potential postnatal energy reserve? We hypothesised that resolving this dilemma operates at the level of umbilical blood distribution entering the fetal liver. In 381 uncomplicated pregnancies in third trimester, we measured blood flow perfusing the fetal liver, or bypassing it via the ductus venosus to supply the brain and heart using ultrasound techniques. Across the range of fetal growth and independent of the mother's adiposity and parity, greater liver blood flow was associated with greater offspring fat mass measured by dual-energy X-ray absorptiometry, both in the infant at birth (r?=?0.43, P<0.001) and at age 4 years (r?=?0.16, P?=?0.02). In contrast, smaller placentas less able to meet fetal demand for essential nutrients were associated with a brain-sparing flow pattern (r?=?0.17, p?=?0.02). This flow pattern was also associated with a higher degree of shunting through ductus venosus (P?=?0.04). We propose that humans evolved a developmental strategy to prioritize nutrient allocation for prenatal fat deposition when the supply of conditionally essential nutrients requiring hepatic inter-conversion is limited, switching resource allocation to favour the brain if the supply of essential nutrients is limited. Facilitated placental transfer mechanisms for glucose and other nutrients evolved in environments less affluent than those now prevalent in developed populations, and we propose that in circumstances of maternal adiposity and nutrient excess these mechanisms now also lead to prenatal fat deposition. Prenatal developmental influences play important roles in the human propensity to deposit fat.
Project description:The human fetal liver is a critical organ for prenatal hematopoiesis, the study of which offers insights into niche signals that regulate the fates of hematopoietic stem and progenitor cells (HSPCs) during fetal development. Here, we demonstrate that human fetal liver endothelium uniquely supports the maturation and expansion of multilineage HSPCs. Specifically, co-culture of fetal liver-derived immature CD43+CD45- hematopoietic cells with human fetal liver endothelial cells (ECs) led to a profound increase in the numbers of phenotypic CD45+CD34+ HSPCs and multilineage colony-forming progenitors generated in vitro, when compared to co-culture with ECs derived from other organs. We further identified a supportive role for EC-derived WNT5A in this process via gain- and loss-of-function studies within ECs. Our study emphasizes the importance of the organ-specific endothelial niche in supporting hematopoietic development and provides novel insight into signals that may facilitate HSPC expansion in vitro for clinical applications.
Project description:Although adult mouse hematopoietic stem cells (HSCs) have been purified to near homogeneity, it remains impossible to achieve this with fetal HSCs. Adult HSC purity recently has been enhanced using the SLAM family receptors CD150, CD244, and CD48. These markers are expressed at different stages of the hematopoiesis hierarchy, making it possible to highly purify adult HSCs as CD150(+)CD48(-)CD244(-) cells. We found that SLAM family receptors exhibited a similar expression pattern in fetal liver. Fetal liver HSCs were CD150(+)CD48(-)CD244(-), and the vast majority of colony-forming progenitors were CD48(+)CD244(-)CD150(-) or CD48(+)CD244(+)CD150(-), just as in adult bone marrow. SLAM family markers enhanced the purification of fetal liver HSCs. Whereas 1 (11%) of every 8.9 Thy(low)Sca-1(+)lineage(-)Mac-1(+) fetal liver cells gave long-term multilineage reconstitution in irradiated mice, 1 (18%) of every 5.7 CD150(+)CD48(-)CD41(-) cells and 1 (37%) of every 2.7 CD150(+)CD48(-)Sca-1(+)lineage(-)Mac-1(+) fetal liver cells gave long-term multilineage reconstitution. These data emphasize the robustness with which SLAM family markers distinguish progenitors at different stages of the hematopoiesis hierarchy and enhance the purification of definitive HSCs from diverse contexts. Nonetheless, CD150, CD244, and CD48 are not pan-stem cell markers, as they were not detectably expressed by stem cells in the fetal or adult nervous system.
Project description:The fetal liver (FL) is the main hematopoietic organ during embryonic development. The FL is also the unique anatomical site where hematopoietic stem cells expand before colonizing the bone marrow, where they ensure life-long blood cell production and become mostly resting. The identification of the different cell types that comprise the hematopoietic stroma in the FL is essential to understand the signals required for the expansion and differentiation of the hematopoietic stem cells. We used a panel of monoclonal antibodies to identify FL stromal cells in a 5-laser equipped spectral flow cytometry (FCM) analyzer. The "Autofluorescence Finder" of SONY ID7000 software identified two distinct autofluorescence emission spectra. Using autofluorescence as a fluorescence parameter we could assign the two autofluorescent signals to three distinct cell types and identified surface markers that characterize these populations. We found that one autofluorescent population corresponds to hepatoblast-like cells and cholangiocytes whereas the other expresses mesenchymal transcripts and was identified as stellate cells. Importantly, after birth, autofluorescence becomes the unique identifying property of hepatoblast-like cells because mature cholangiocytes are no longer autofluorescent. These results show that autofluorescence used as a parameter in spectral FCM is a useful tool to identify new cell subsets that are difficult to analyze in conventional FCM.