Multimodal decoding of human liver regeneration.

The liver has a unique ability to regenerate1,2; however, in the setting of acute liver failure (ALF), this regenerative capacity is often overwhelmed, leaving emergency liver transplantation as the only curative option3-5. Here, to advance understanding of human liver regeneration, we use paired single-nucleus RNA sequencing combined with spatial profiling of healthy and ALF explant human livers to generate a single-cell, pan-lineage atlas of human liver regeneration. We uncover a novel ANXA2+ migratory hepatocyte subpopulation, which emerges during human liver regeneration, and a corollary subpopulation in a mouse model of acetaminophen (APAP)-induced liver regeneration. Interrogation of necrotic wound closure and hepatocyte proliferation across multiple timepoints following APAP-induced liver injury in mice demonstrates that wound closure precedes hepatocyte proliferation. Four-dimensional intravital imaging of APAP-induced mouse liver injury identifies motile hepatocytes at the edge of the necrotic area, enabling collective migration of the hepatocyte sheet to effect wound closure. Depletion of hepatocyte ANXA2 reduces hepatocyte growth factor-induced human and mouse hepatocyte migration in vitro, and abrogates necrotic wound closure following APAP-induced mouse liver injury. Together, our work dissects unanticipated aspects of liver regeneration, demonstrating an uncoupling of wound closure and hepatocyte proliferation and uncovering a novel migratory hepatocyte subpopulation that mediates wound closure following liver injury. Therapies designed to promote rapid reconstitution of normal hepatic microarchitecture and reparation of the gut-liver barrier may advance new areas of therapeutic discovery in regenerative medicine.

Early derangement of INR predicts liver failure after liver resection for hepatocellular carcinoma.

BACKGROUND: Surgical resection, where appropriate, remains one of the best treatment options for hepatocellular carcinoma (HCC), however outcomes can be compromised by the development of liver failure. We reviewed our experience of liver resection for HCC patients to identify factors that may predict the development of post-hepatectomy liver failure (PHLF) and survival. METHODS: A single centre retrospective cohort study. Data was collected between 1999 and 2017 from all patients undergoing HCC resection in a tertiary university hospital from electronic medical records. PHLF was defined as per the International Study Group for Liver Surgery criteria. Variables with p < 0.15 on univariate analysis were included in a multivariate binary logistic regression model. Kaplan-Meier analyses were used to determine correlations with overall survival (OS) and disease-free survival (DFS), and variables with p < 0.15 on univariate analysis selected for a step-down Cox proportional hazard regression model. RESULTS: Overall, 120 patients underwent liver resection within the study period, of which 22 (18%) developed PHLF. Patients with normal INR ≤1.20 at day 2 did not develop PHLF whereas patients with INR >1.60 were at significant risk. Resection of multiple tumours (odds ratio 21.63, p = 0.002) and deranged postoperative day 2 INR>1.6 (odds ratio 21.05, p < 0.0001) were identified as independent prognostic markers of PHLF. CONCLUSION: The use of INR measurement at day 2 predicts PHLF and may enable us to objectively identify and stratify patients who may be eligible for enhanced recovery programs from those who will merit close monitoring in high dependency areas.

An ultra scale-down analysis of the recovery by dead-end centrifugation of human cells for therapy.

An ultra scale-down method is described to determine the response of cells to recovery by dead-end (batch) centrifugation under commercially defined manufacturing conditions. The key variables studied are the cell suspension hold time prior to centrifugation, the relative centrifugal force (RCF), time of centrifugation, cell pellet resuspension velocities, and number of resuspension passes. The cell critical quality attributes studied are the cell membrane integrity and the presence of selected surface markers. Greater hold times and higher RCF values for longer spin times all led to the increased loss of cell membrane integrity. However, this loss was found to occur during intense cell resuspension rather than the preceding centrifugation stage. Controlled resuspension at low stress conditions below a possible critical stress point led to essentially complete cell recovery even at conditions of extreme centrifugation (e.g., RCF of 10000 g for 30 mins) and long (~2 h) holding times before centrifugation. The susceptibility to cell loss during resuspension under conditions of high stress depended on cell type and the age of cells before centrifugation and the level of matrix crosslinking within the cell pellet as determined by the presence of detachment enzymes or possibly the nature of the resuspension medium. Changes in cell surface markers were significant in some cases but to a lower extent than loss of cell membrane integrity.

Ultra scale-down stress analysis of the bioprocessing of whole human cells as a basis for cancer vaccines.

This study examines the use of a capillary shear device for the rapid characterization of human cell lines in terms of their resistance to hydrodynamic stress. An ultra scale-down (USD) approach is presented to allow the use of small quantities of cells available at the early discovery stage and to expose them to a wide range of hydrodynamic stresses. In this way an indication is gained of the relative properties of different cell lines and the challenge which may be faced during full-scale processing. A design of experiments approach allowed the interaction between a number of key processing factors such as capillary length, flow rate, and number of passes to be studied in a limited number of experiments. Out of this an USD test based on flow rate in a device of fixed geometry was proposed. Based on observations made elsewhere (Ma et al., 2002, Biotechnol Bioeng 80(4): 428-437) a detailed analysis of possible geometries was performed using a combination of USD experiments and computational fluid dynamics analysis of the capillary entry region. This allowed the properties of the cells to be characterized in terms of a critical stress below which there is no significant loss of cell integrity. The results suggested that the OnyCap23 and P4E6 cell lines, used as components of a whole cell prostate cancer vaccine, are resistant to damage below critical elongational shear stress values of 235 and 275 N/m(2), respectively. Above these stress values the loss of intact cells is predicted to be significant; such loss being due to a combination of whole cells becoming permeable to trypan blue and complete breakage of cells into debris at extreme stresses. The sensitivity of cell surface markers CD9, CD44, CD59, CD81, CD147, and MHC-1 to exposure to shear stress was considerably less than for cell membrane integrity. The surface marker levels for recovered whole cells (i.e., both with and without intact cell membranes) were either independent of shear stress or showed a slight decrease with increased shear stress, for example, as for CD9. The results were used to predict successfully a capillary design where no damage would occur at a specified high flow rate; for example, as required for cell dispensing or vialling operations. Equally, the extent of loss of cell integrity was also successfully predicted in a capillary flow system designed to yield high levels of break up as may be required in intracellular analysis without the use of chemical lysing reagents or relying on autolytic damage.

Rapid whole monoclonal antibody analysis by mass spectrometry: An ultra scale-down study of the effect of harvesting by centrifugation on the post-translational modification profile.

With the trend towards the generation and production of increasing numbers of complex biopharmaceutical (protein based) products, there is an increased need and requirement to characterize both the product and production process in terms of robustness and reproducibility. This is of particular importance for products from mammalian cell culture which have large molecular structures and more often than not complex post-translational modifications (PTMs) that can impact the efficacy, stability and ultimately the safety of the final product. It is therefore vital to understand how the operating conditions of a bioprocess affect the distribution and make up of these PTMs to ensure a consistent quality and activity in the final product. Here we have characterized a typical bioprocess and determined (a) how the time of harvest from a mammalian cell culture and, (b) through the use of an ultra scale-down mimic how the nature of the primary recovery stages, affect the distribution and make up of the PTMs observed on a recombinant IgG(4) monoclonal antibody. In particular we describe the use of rapid whole antibody analysis by mass spectrometry to analyze simultaneously the changes that occur to the cleavage of heavy chain C-terminal lysine residues and the glycosylation pattern, as well as the presence of HL dimers. The time of harvest was found to have a large impact upon the range of glycosylation patterns observed, but not upon C-terminal lysine cleavage. The culture age had a profound impact on the ratio of different glycan moieties found on antibody molecules. The proportion of short glycans increased (e.g., (G0F)(2) 20-35%), with an associated decrease in the proportion of long glycans with culture age (e.g., (G2F)(2) 7-4%, and G1F/G2F from 15.2% to 7.8%). Ultra scale-down mimics showed that subsequent processing of these cultures did not change the post-translational modifications investigated, but did increase the proportion of half antibodies present in the process stream. The combination of ultra scale-down methodology and whole antibody analysis by mass spectrometry has demonstrated that the effects of processing on the detailed molecular structure of a monoclonal antibody can be rapidly determined early in the development process. In this study we have demonstrated this analysis to be applicable to critical process design decisions (e.g., time of harvest) in terms of achieving a desired molecular structure, but this approach could also be applied as a selection criterion as to the suitability of a platform process for the preparation of a new drug candidate. Also the methodology provides means for bioprocess engineers to predict at the discovery phase how a bioprocess will impact upon the quality of the final product.

Cross-linked actin networks (CLANs) in bovine trabecular meshwork cells.

A cytoskeletal feature of human trabecular meshwork (HTM) cells in vitro and ex vivo is the presence of cross-linked actin networks (CLANs) that are abundant in a proportion of TM cells exposed to dexamethasone (DEX) and also in cells from glaucoma patients. We wished to determine whether CLANs were present in the bovine trabecular meshwork (BTM), whether they were similarly induced by dexamethasone and whether the structures were comparable to CLANs in HTM cells. Cultures of HTM and BTM cells and ex vivo dissections of BTM tissue were stained with phalloidin (F-actin) and propidium iodide (nuclei) and imaged by confocal microscopy, thereafter being subjected to image analysis. Some CLAN-like structures were identified in ex vivo BTM tissue cultured with and without DEX. However we found that BTM cells in culture produced abundant CLANs when exposed to DEX; comparable to the best response from HTM cells. The CLANs were of similar dimensions and morphology to those found in human cells and they had a similar half life of 2 or 3 days following the removal of DEX. This work demonstrates that BTM cells provide a suitable model for future investigations of CLAN formation and function. BTM cultures are sufficiently hardy to thrive in low serum and serum-free conditions so we were able to show that aqueous humor stimulates CLAN formation in the target cells. Future research is directed at identifying the aqueous component(s) responsible for CLAN production.

Ultra scale-down prediction using microwell technology of the industrial scale clarification characteristics by centrifugation of mammalian cell broths.

This article describes how a combination of an ultra scale-down (USD) shear device feeding a microwell centrifugation plate may be used to provide a prediction of how mammalian cell broth will clarify at scale. In particular a method is described that is inherently adaptable to a robotic platform and may be used to predict how the flow rate and capacity (equivalent settling area) of a centrifuge and the choice of feed zone configuration may affect the solids carry over in the supernatant. This is an important consideration as the extent of solids carry over will determine the required size and lifetime of a subsequent filtration stage or the passage of fine particulates and colloidal material affecting the performance and lifetime of chromatography stages. The extent of solids removal observed in individual wells of a microwell plate during centrifugation is shown to correlate with the vertical and horizontal location of the well on the plate. Geometric adjustments to the evaluation of the equivalent settling area of individual wells (Sigma(M)) results in an improved prediction of solids removal as a function of centrifuge capacity. The USD centrifuge settling characteristics need to be as for a range of equivalent flow rates as may be experienced at an industrial scale for a machine of different shear characteristics in the entry feed zone. This was shown to be achievable with two microwell-plate based measurements and the use of varying fill volumes in the microwells to allow the rapid study of a fivefold range of equivalent flow rates (i.e., at full scale for a particular industrial centrifuge) and the effect of a range of feed configurations. The microwell based USD method was used to examine the recovery of CHO-S cells, prepared in a 5 L reactor, at different points of growth and for different levels of exposure to shear post reactor. The combination of particle size distribution measurements of the cells before and after shear and the effect of shear on the solids remaining after centrifugation rate provide insight into the state of the cells throughout the fermentation and the ease with which they and accumulated debris may be removed by continuous centrifugation. Hence bioprocess data are more readily available to help better integrate cell culture and cell removal stages and resolve key bioprocess design issues such as choice of time of harvesting and the impact on product yield and contaminant carry over. Operation at microwell scale allows data acquisition and bioprocess understanding over a wide range of operating conditions that might not normally be achieved during bioprocess development.

Regenerative medicine bioprocessing: concentration and behavior of adherent cell suspensions and pastes.

Regenerative medicines based on human cells demand their harvesting, culture, and processing. Manufacturing processes are likely to include cell concentration and subsequent controlled dosing of concentrates, for example, to the patient or tissue construct. The integrity and functionality of the cells must be maintained during these processing stages. In this study the performance of two different cell concentration protocols (involving centrifugation and resuspension) are compared and consideration given to possible causes of cell loss. Further studies examine cell size and rheological behavior of anchorage-dependent mammalian cell suspensions, and the effect of capillary flow stress (0.5-15 Pa, laminar flow regime) on cell number and membrane integrity as quantified by flow cytometry. The cell concentration protocols achieved maximum cell volume fraction of around 0.3 and the improved protocol exhibited intact cell yield of 80 +/- 13%, demonstrating proof-of principle for achieving tissue-like cell concentrations by a process of centrifugation and orbital shaking. Volume mean cell diameter (cell diameter at the mean cell volume) for the rat aortic smooth muscle cells (CRL-1444) used in this study was 22.4 microm. Concentrated cell suspension rheology approximated to power law behavior and exhibited similar trends to reports for plant and yeast cells. Capillary transfer at 2-15 Pa (wall shear stress) did not significantly affect cell number or membrane integrity while losses observed at low shear (0.5, 1.0 Pa) were probably due to surface attachment of cells in the apparatus.

Publisher Correction: Measuring the ionisation fraction in a jet from a massive protostar.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Measuring the ionisation fraction in a jet from a massive protostar.

It is important to determine if massive stars form via disc accretion, like their low-mass counterparts. Theory and observation indicate that protostellar jets are a natural consequence of accretion discs and are likely to be crucial for removing angular momentum during the collapse. However, massive protostars are typically rarer, more distant and more dust enshrouded, making observational studies of their jets more challenging. A fundamental question is whether the degree of ionisation in jets is similar across the mass spectrum. Here we determine an ionisation fraction of ~5-12% in the jet from the massive protostar G35.20-0.74N, based on spatially coincident infrared and radio emission. This is similar to the values found in jets from lower-mass young stars, implying a unified mechanism of shock ionisation applies in jets across most of the protostellar mass spectrum, up to at least ~10 solar masses.

Micro biochemical engineering to accelerate the design of industrial-scale downstream processes for biopharmaceutical proteins.

The article examines how a small set of easily implemented micro biochemical engineering procedures combined with regime analysis and bioprocess models can be used to predict industrial scale performance of biopharmaceutical protein downstream processing. This approach has been worked on in many of our studies of individual operations over the last 10 years and allows preliminary evaluation to be conducted much earlier in the development pathway because of lower costs. It then permits the later large scale trials to be more highly focused. This means that the risk of delays during bioprocess development and of product launch are reduced. Here we draw the outcomes of this research together and illustrate its use in a set of typical operations; cell rupture, centrifugation, filtration, precipitation, expanded bed adsorption, chromatography and for common sources, E. coli, two yeasts and mammalian cells (GS-NSO). The general approach to establishing this method for other operations is summarized and new developments outlined. The technique is placed against the background of the scale-down methods that preceded it and complementary ones that are being examined in parallel. The article concludes with a discussion of the advantages and limitations of the micro biochemical engineering approach versus other methods.

The impact of process stress on suspended anchorage-dependent mammalian cells as an indicator of likely challenges for regenerative medicines.

To quantify the engineering shear constraint on processing, the effect of capillary shear stress (pipe flow) on suspended anchorage-dependent mammalian cells has been investigated. Exposure of cultured rat aortic smooth muscle cells to repeated capillary shear stress (2-120 N m(-2)) causes a decrease in total number of cells, number of intact cells and number of cells able to grow. The optimum wall shear stress for cell survival was found to be 10-50 N m(-2) (flowrate 4-20 mL/min, I.D. 0.45 mm). Cell populations which are able to grow after exposure to shear stress do not exhibit reduced growth rate or altered metabolism.

Impact of clarification strategy on chromatographic separations: Pre-processing of cell homogenates.

This research focused on how the extent and type of primary solid-liquid separation can affect the performance of guard filtration and chromatography, in this instance hydrophobic interaction chromatography. The system used in the study was yeast (Saccharomyces cerevisiae) with the target molecule being an intracellular protein; alcohol dehydrogenase (ADH). As expected, loading more poorly clarified suspensions (both centrates and primary filtrates) required proportionally larger guard filtration areas. In addition for feed suspensions prepared by centrifugation, increased clarification led to greater column capacity. However, where filtration was used to achieve similar clarification considerably lower column capacity was achieved. These results were attributed to centrifugation leading to the aggregation of lipids and their subsequent removal in this form before application to the column. Clarification by filtration leaves such lipids in their original "soluble" state and hence they are not removed. The importance of the need to examine such interactive effects in bioprocess studies is discussed. This observation was confirmed with further analytical work into the nature of the aggregated material formed in the supernatant under centrifugation conditions. This material was only soluble in an organic solvent, and identified as phophatidylcholine and ergosterol as among the components removed by centrifugation and guard filtration as opposed to filtration and guard filtration.

A retrospective 15-year review: survival advantage after switching to sirolimus in hepatitis C virus infected liver graft recipients.

BACKGROUND: The use of sirolimus-based immune suppression in liver transplantation, particularly in hepatitis C virus (HCV)-infected recipients, remains contentious. There is some evidence that sirolimus retards hepatic fibrosis, is renal sparing and may be of benefit in preventing hepatocellular carcinoma (HCC) recurrence. Sirolimus has not been adopted by many transplant centres because of persistent concerns regarding an increased risk of hepatic artery thrombosis, graft loss and death with de novo sirolimus. AIM: To review the impact of switching to sirolimus monotherapy in HCV-infected liver recipients with respect to survival, graft loss and hepatic fibrosis. METHODS: A retrospective review of 190 patients from a single centre undergoing first liver transplantation for HCV over 15 years. 113 patients were switched from calcineurin inhibitor (CNI)-based therapy to low-dose sirolimus monotherapy at a median of 15 months after transplantation for HCV-related fibrosis (72%), renal impairment (14%) or high-risk HCC (5%). RESULTS: Patients switched to sirolimus had improved survival (P < 0.001) and slower progression to cirrhosis (P = 0.001). In patients with HCC (n = 91), sirolimus duration rather than strategy was an independent predictor of survival (P = 0.001) and extended time to HCC recurrence (33 vs. 16 months). Patients switched for renal dysfunction showed improvement in serum creatinine (140-108 µmol/L, P = 0.001). Those remaining on CNI-therapy were more likely to develop post-transplant diabetes (P = 0.03). CONCLUSION: These data suggest selective switching to low-dose sirolimus monotherapy in HCV-positive liver recipients improves clinical outcome.

Posttranslational processing of recombinant human interferon-gamma in animal expression systems.

We have characterized the heterogeneity of recombinant human interferon-gamma (IFN-gamma) produced by three expression systems: Chinese hamster ovary cells, the mammary gland of transgenic mice, and baculovirus-infected Spodopera frugiperda (Sf9) insect cells. Analyses of whole IFN-gamma proteins by electrospray ionization-mass spectrometry (ESI-MS) from each recombinant source revealed heterogeneous populations of IFN-gamma molecules resulting from variations in N-glycosylation and C-terminal polypeptide cleavages. A series of more specific analyses assisted interpretation of maximum entropy deconvoluted ESI-mass spectra of whole IFN-gamma proteins; MALDI-MS analyses of released, desialylated N-glycans and of deglycosylated IFN-gamma polypeptides were combined with analyses of 2-aminobenzamide labeled sialylated N-glycans by cation-exchange high-performance liquid chromatography. These analyses enabled identification of specific polypeptide cleavage sites and characterization of associated N-glycans. Production of recombinant IFN-gamma in the mammalian expression systems yielded polypeptides C-terminally truncated at dibasic amino acid sites. Mammalian cell derived IFN-gamma molecules displayed oligosaccharides with monosaccharide compositions equivalent to complex, sialylated, or high-mannose type N-glycans. In contrast, IFN-gamma derived from baculovirus-infected Sf9 insect cells was truncated further toward the C-terminus and was associated with neutral (nonsialylated) N-glycans. These data demonstrate the profound influence of host cell type on posttranslational processing of recombinant proteins produced in eukaryotic systems.

Distribution of the receptor EphA7 and its ligands in development of the mouse nervous system.

EphA7 is a receptor tyrosine kinase of the Eph family. We have mapped EphA7 immunoreactivity and ligand binding in mouse embryo heads and developing brain. Immunoreactivity for the full-length receptor is found in all the cell populations that express EphA7 mRNA. In particular, it is located on growing axons from EphA7-expressing neurons, both in the trigeminal nerve and in developing brain. In many cases it persists in terminal fields in adult brain. Ligand is detected in a largely complementary distribution in embryos, but is surprisingly weak or undetectable in the target regions of many EphA7-positive axons postnatally.

Intermittent sequential pneumatic compression of the legs and thromboembolism-deterrent stockings in the prevention of postoperative deep venous thrombosis.

One hundred fifty patients over the age of 30 who had undergone major abdominal operations were stratified according to the risk of deep venous thrombosis and randomized into three groups to receive different prophylactic regimens: group A, electrical calf stimulation; group B, low-dose subcutaneous heparin; group C, intermittent sequential compression and thromboembolism-deterrent (TED) stockings. All the patients were scanned with the 125I-fibrinogen test for the whole stay in hospital. The incidence of 125I-fibrinogen detected deep venous thrombi was 18% in group A, 9% in group B, and 4% in group C. The results indicate that the regimen of intermittent sequential compression and TED stockings is as effective as low-dose subcutaneous heparin. Electrical calf stimulation is less effective.

The role of primary varicose veins in venous ulceration.

"Venous" ulceration is usually ascribed to deep venous insufficiency. We record the cases of 20 patients with 23 ulcers without a history suggestive of deep vein disease who were found to have a normal deep venous system when evaluated by Doppler ultrasound, ambulatory venous pressures, and photoplethysmography. All had gross varicose veins present for many years (mean 24 years; range 10 to 35 years), and only 14 limbs had incompetent calf perforating veins. Effective treatment is facilitated by recognition of the relationship of varicose ulcer to superficial venous disease, usually incompetence of the saphenofemoral junction, with or without the presence of incompetent calf perforating veins.

Prostaglandin E1 in severe Raynaud's phenomenon.

Twenty-one patients with severe Raynaud's phenomenon were treated on 29 occasions with prostaglandin E1 (PGE1), a potent vasodilator and pyrogen. A history of finger sepsis or necrosis was absent in 8 (group I) and present in 13 (group II). Three group I and eight group II patients had an associated connective tissue disease, and previously eight upper limbs had been sympathectomized in six group I patients and 14 upper limbs in eight group II patients. A total of 12 fingers had been amputated in six group II patients. Treatment comprised antibiotics for sepsis, PGE1 intravenously for 72 hours, and subsequent surgical debridement of septic and necrotic tissue in 30 fingers of eight group II patients under general anesthesia. Finger skin temperature measured half-hourly in a temperature-controlled ward cubicle (23.7 degrees +/- 0.7 degrees C), Doppler-detectable digital arterial flow, and finger/brachial systolic pressure index with local finger cooling to 10 degrees C were not improved by the administration of 0.9% saline for 72 hours, but were all significantly improved after PGE1 administration. Finger skin temperature was significantly elevated 11 weeks after treatment. The symptoms did not improve after PGE1 administration in group I patients but did improve in 12 of 13 group II patients. No finger deteriorated, and all debrided fingers healed after surgery. Nail bed removal in 11 fingers met with patient approval and prevented recurrent sepsis and necrosis. PGE1 provides a means of increasing finger blood flow during acute exacerbations of finger sepsis and necrosis; unlike sympathectomy, it is a minor procedure without prolonged side effects and is repeatable.

An optical biosensor for real-time chromatography monitoring: breakthrough determination.

The use of an optical biosensor for immunorecognition of protein products during affinity chromatography is discussed to provide rapid data describing the loading and subsequent breakthrough, followed by elution and fraction collection. The optical biosensor works by following in real-time the interaction of soluble ligate with an appropriate ligand attached to the optically active surface. The initial rate of interaction between soluble ligate and immobilized ligand has been shown to correlate well with ligate concentration. This method of analysis has also been shown to agree well with ELISA, the traditionally employed technique for immunoassay of protein products lacking, for example, catalytic activity. Forward prediction, using models of the breakthrough fitted to the real-time data, has enabled the column saturation point to be determined before it has been reached, thus enabling appropriate action to ensure minimal loss of protein product while improving column utilization efficiency. The biosensor, operated within a flow injection analysis regime, has been demonstrated to provide concentration data within 10 s, with a total assay turnaround of 30 s.