Project description:The liver’s remarkable capacity to regenerate allows it to carry out vital life-supporting functions despite unrelenting pathogen and toxin-induced injury. Unchecked, this capability also leads to cirrhosis, a burgeoning global disease burden. Existing animal models only partially recapitulate human liver regeneration, which hitherto has not been systematically studied. We investigated human liver regeneration in a unique model of liver transplantation. Here we show coordinated changes in expression of microRNA (miRNA) during regeneration that drive proliferation, innate immunity and angiogenesis. Failed regeneration is associated with distinct miRNAs enforcing cell cycle inhibition and DNA methylation. The miRNA expression associated with successful or failed regeneration when recapitulated in vitro, triggered expression of cardinal regeneration-linked genes promoting cell cycle entry or inhibition, respectively. Furthermore, inhibition of three miRNAs whose downregulation is associated with successful regeneration, induced proliferation in vitro. Our data indicate that human liver regeneration is orchestrated by distinct miRNAs determining cell cycle fate. Their manipulation may obviate the need for transplantation by enforcing successful regeneration in the liver and other solid organs.
Project description:The liverM-bM-^@M-^Ys remarkable capacity to regenerate allows it to carry out vital life-supporting functions despite unrelenting pathogen and toxin-induced injury. Unchecked, this capability also leads to cirrhosis, a burgeoning global disease burden. Existing animal models only partially recapitulate human liver regeneration, which hitherto has not been systematically studied. We investigated human liver regeneration in a unique model of liver transplantation. Here we show coordinated changes in expression of microRNA (miRNA) during regeneration that drive proliferation, innate immunity and angiogenesis. Failed regeneration is associated with distinct miRNAs enforcing cell cycle inhibition and DNA methylation. The miRNA expression associated with successful or failed regeneration when recapitulated in vitro, triggered expression of cardinal regeneration-linked genes promoting cell cycle entry or inhibition, respectively. Furthermore, inhibition of three miRNAs whose downregulation is associated with successful regeneration, induced proliferation in vitro. Our data indicate that human liver regeneration is orchestrated by distinct miRNAs determining cell cycle fate. Their manipulation may obviate the need for transplantation by enforcing successful regeneration in the liver and other solid organs. We compared a group of seven patients with successful regeneration (RG) after auxiliary liver transplant (ALT) to four patients who also had ALT but failed to regenerate (NRG). Regeneration was quantified by volume expansion using radiographic imaging; functional recovery was assessed using nuclear isotope scanning and hepatocellular regeneration using histology. Based on histological assessment, three time points were selected for both groups (RG and NRG). Biopsies were taken at the time of transplant and at different intervals post-transplant. Since sample acquisition was driven by clinical necessity, widely discrepant time intervals existed between T=1, T=2 and T=3 for the patients. RNA was extracted from archived histology samples of the RG and NRG, and miRNA expression was analysed using the Affymetrix GeneChip miRNA 1.0 assays. This submission does not include NRG samples taken at time point 3.
Project description:This study aimed to improve our understanding of the mechanisms of liver regeneration in sharks and to identify the microRNAs that participate in liver regeneration and other liver-related diseases. To this end, normal and regenerating liver tissues from C. plagiosum were harvested 0, 3, 6, 12 and 24 h after partial hepatectomy (PH) and were sequenced using the Illumina/Solexa platform. In total, 309 known microRNAs and 590 novel microRNAs were identified in C. plagiosum. There were 368 microRNAs differentially expressed between the normal and regenerating livers. Using target prediction and GO analysis, most of the differentially expressed microRNAs were assigned to functional categories that may be involved in regulating liver regeneration, such as cell proliferation, differentiation and apoptosis. Additionally, this study adds several novel microRNAs to the database, which will help identify microRNAs in other genetically related species and provides a starting point for future studies aimed at understanding the roles of microRNAs in liver regeneration and other liver diseases.
Project description:Introduction: Bone healing is a well-orchestrated process involving various bone cells and signaling pathways, where disruptions can result in delayed or incomplete healing. MicroRNAs (miRNAs) are small non-coding RNAs capable of influencing various cellular processes, including bone remodeling. Due to their biological relevance and stable presence in biofluids, miRNAs may serve as candidates for diagnosis and prognosis of delayed bone healing. The aim of this study was to investigate changes in miRNAs circulating in the blood during the healing of rat calvaria defects as biomarkers of successful bone regeneration. Methods: Standardized calvaria defects were created in 36 Wistar rats with a trephine drill and treated with collagen hydroxyapatite (CHA) scaffolds. The treatment groups included CHA scaffolds only, CHA scaffolds containing a plasmid coding for bone morphogenetic protein 2 (BMP2) and miR-590-5p, CHA scaffolds containing mesenchymal stromal cell-derived extracellular vesicles, and empty defects as a control group. After 1, 4 and 8 weeks of healing, the animals were evaluated by microcomputed tomography (microCT), as well as subjected to histological analyses. Blood was sampled from the tail vein prior to surgeries and after 1, 4, and 8 weeks of healing. miRNAs circulating in the plasma were determined using next generation sequencing. Results: Variability of bone regeneration within the four groups was unexpectedly high and did not result in significant differences between the groups, as indicated by the microCT and histological analyses of the newly formed bone tissue. However, irrespective of the treatment group and regenerative activity, we identified miRNAs with distinct expression patterns of up- and downregulation at different time points. Furthermore, rats with high and low regenerative activity were characterized by distinct circulating miRNA profiles. miR-133-3p was identified as the top up-regulated miRNA and miR-375-3p was identified as the top down- regulated miRNA in animals exhibiting good regeneration over all time points evaluated. Conclusion: Our study indicates that regardless of the treatment group, success or lack of bone regeneration is associated with a distinct expression pattern of circulating microRNAs. While for some of these microRNAs functional association with skeletal regeneration has previously been reported, further research is needed to evaluate whether their levels in the blood can be used as predictive factors of successful bone regeneration. Keywords: gene-activated scaffold; osteogenesis; bone regeneration, biomarkers, circulating microRNAs
Project description:Previous studies of zebrafish caudal fin regeneration have shown that multiple genetic programs are moduled through regulatory factors. MicroRNAs are short highly conserved non-coding genes that suppress expression of target genes and thereby control multiple genetic programs. Given their important regulatory roles and evolutionary conservation, we hypothesize that microRNAs define a conserved genetic regulatory circuit important for appendage regeneration. We characterized microRNA expression during zebrafish caudal fin regeneration using small RNA sequencing. The stages of caudal fin regeneration were assayed for mRNA expression using mRNA sequencing. Small RNA and mRNA gene expression profiling during 0 and 4 days post amputation.
Project description:Successful regeneration of injured neurons requires a complex molecular response that involves the expression, modification and transport of large numbers of proteins. The neuronal proteins responsible for the initiation of regenerative neurite outgrowth are largely unknown. Dorsal root ganglion (DRG) neurons display robust and successful regeneration following lesion of their peripheral neurite, whereas outgrowth of central neurites is weak and does not lead to functional recovery. We have utilized this differential response to gain insight in the early transcriptional events associated with successful regeneration. Surprisingly, our study shows that peripheral and central nerve crushes elicit very distinct transcriptional activation, revealing a large set of novel genes that are differentially regulated within the first 24 hours after the lesion. A large number of known regeneration associated genes were retrieved in our study, and, in addition, hundreds of novel genes possibly involved in the transcriptional regulatory network underlying successful regeneration. Please refer to Stam et al., Eur. J. Neurosci 25:3629 (2007). Keywords: time course
Project description:The liver has a remarkable ability to regenerate, with the best experimental model for regeneration being partial hepatectomy (PHx), in which up to two-thirds of the liver may be removed, and the residual lobes enlarge to make up for the missing mass in a few days’ time. Liver regeneration has been extensively studied, mainly in rodent models, and characterized in terms of transcriptional regulation of gene expression. However, little is known regarding regulation of gene expression in a human model of regeneration following PHx. We used microarrays to follow gene expression changes shortly following PHx. Experiment Overall Design: Liver tissues were collected from patients undergoing a PHx surgery (1.5, 42 and 81 years) under an IRB approval, at the onset (T0) and shortly after PHx (0.5hr, 1hr and 1.5hrs) for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Liver regeneration following resection is a complex process relying on coordinated pathways and cell types in the remnant organ. Myeloid-Derived Suppressor Cells (MDSCs) have a role in liver regeneration-related angiogenesis but their influence on hepatocyte proliferation and immune modulation during liver regeneration is unclear. We examined the transcriptional response of regenerating liver hepatocytes after major resection in mice with CD11b+Ly6G+ MDSCs (G-MDSCs) depletion using RNA sequencing. Global gene expression profiling of regenerating hepatocytes upon G-MDSC depletion revealed disrupted transcriptional progression from day one to day two after major liver resection. Key genes and pathways related to hepatocyte proliferation and immune response were differentially expressed upon MDSC depletion. This study provides evidence that MDSCs contribute to early liver regeneration by promoting hepatocyte proliferation and modulating the intra-liver immune response. These findings illuminate the multifaceted role of MDSCs in liver regeneration.