CIRSE Standards of Practice on Bronchial Artery Embolisation.

This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for performing bronchial artery embolisation to effectively treat haemoptysis. It has been developed by an expert writing group established by the CIRSE Standards of Practice Committee.

Radiation dose reduction during adrenal vein sampling using a new angiographic imaging technology.

To compare the patient radiation doses during angiographic selective adrenal vein sampling (AVS) before and after an imaging technology upgrade. In this retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), fluoroscopy time and contrast agent dosage were recorded from 70 patients during AVS. 35 procedures were performed before and 35 after an imaging processing technology upgrade. Mean values were calculated and compared using an unpaired student's t-test. DSA image quality was assessed independently by two blinded readers using a four-point Likert scale (1 = poor; 4 = excellent) and compared using Wilcoxon signed-rank test. After the technology upgrade we observed a significant reduction of 35% in AK (1.7 ± 0.7 vs. 1.1 ± 0.7 Gy, p = 0.01) and a significant reduction of 28% in DAP (235.1 ± 113 vs. 170.1 ± 94 Gy*cm2, p = 0.01) in comparison to procedures before the upgrade. There were no significant differences between the number of exposure frames (143 ± 86 vs. 132 ± 61 frames, p = 0.53), fluoroscopy time (42 ± 23 vs. 36 ± 18 min, p = 0.22), or the amount of contrast medium used (179.5 ± 84 vs. 198.1 ± 109 ml, p = 0.41). There was also no significant difference regarding image quality (3 (2-4) vs. 3 (2-4), p = 0.67). The angiographic imaging technology upgrade significantly decreases the radiation dose during adrenal vein sampling without increasing time of fluoroscopy or contrast volume and without compromising image quality.

Sequential Systemic Treatment in Advanced Hepatocellular Carcinoma Is Able to Prolong Median Survival to More than 3 Years in a Selected Real-World Cohort.

INTRODUCTION: The number of efficacious systemic agents for advanced hepatocellular carcinoma (HCC) has rapidly increased over the past 3 years. However, guidance for optimal sequential systemic treatment in patients with advanced disease and experience with outcome and safety profiles are lacking. OBJECTIVE: We aimed to assess efficacy and tolerability of sequential systemic therapy of advanced HCC. METHODS: Our single-center study prospectively followed 14 patients who received multiple, sequential systemic therapies after progression or intolerance to sorafenib. Endpoints were overall and progression-free survival (OS, PFS), objective response rate (ORR), and treatment-emergent adverse events (TEAE). RESULTS: Patients had well-compensated liver function and good performance status at start of each systemic therapy. Agents included sorafenib (n = 14), regorafenib (n = 10), immunotherapy with nivolumab or pembrolizumab (n = 10), lenvatinib (n = 3), ramucirumab (n = 2), and others, with a median of 3 lines of systemic therapy per patient. Median OS was 37.4 months from initiation of first-line therapy with sorafenib. PFS and ORR for sorafenib, regorafenib, and immunotherapy were 6.6, 5.3, and 6.6 months, and 15.4, 11.1, and 22.2%, respectively. TEAE were frequent (46-80%), but mostly manageable during tyrosine kinase inhibitor therapy and without the need for termination in most patients. However, TEAE due to immunotherapy (60%) led to cessation of treatment in 40% of the patients. CONCLUSIONS: Sequential systemic therapy is able to prolong median OS in selected patients with advanced HCC to more than 3 years. TEAE are frequent, but manageable, and the quality of adverse events depends on the respective agent. Further investigation of potential predictive biomarkers for treatment allocation is needed.

Lysosomal lipoprotein processing in endothelial cells stimulates adipose tissue thermogenic adaptation.

In response to cold exposure, thermogenic adipocytes internalize large amounts of fatty acids after lipoprotein lipase-mediated hydrolysis of triglyceride-rich lipoproteins (TRL) in the capillary lumen of brown adipose tissue (BAT) and white adipose tissue (WAT). Here, we show that in cold-exposed mice, vascular endothelial cells in adipose tissues endocytose substantial amounts of entire TRL particles. These lipoproteins subsequently follow the endosomal-lysosomal pathway, where they undergo lysosomal acid lipase (LAL)-mediated processing. Endothelial cell-specific LAL deficiency results in impaired thermogenic capacity as a consequence of reduced recruitment of brown and brite/beige adipocytes. Mechanistically, TRL processing by LAL induces proliferation of endothelial cells and adipocyte precursors via beta-oxidation-dependent production of reactive oxygen species, which in turn stimulates hypoxia-inducible factor-1α-dependent proliferative responses. In conclusion, this study demonstrates a physiological role for TRL particle uptake into BAT and WAT and establishes endothelial lipoprotein processing as an important determinant of adipose tissue remodeling during thermogenic adaptation.

Hepatocellular carcinoma: Intratumoral EpCAM-positive cancer stem cell heterogeneity identifies high-risk tumor subtype.

BACKGROUND: The translational interest in the intratumoral heterogeneity of hepatocellular carcinoma (HCC) has been increasing. The dismal prognosis of this pathology is linked to the features of the HCC harbouring cancer stem cells (CSC), represented by EpCAM-expression. However, the extent of the impact of intratumoral distribution of CSC-features, both on the recurrence after curative resection and on clinical outcome, remains unknown. To address this, we investigated the spatial heterogeneity of CSC-features with the aim of identifying the unique HCC patient subgroups amenable to adjuvant treatment. METHODS: We designed a tissue microarray (TMA) from patients who had received liver resection between 2011 and 2017. Tumor specimens were sampled at multiple locations (n = 3-8). EpCAM-positivity was assessed for intensity and proportion by applying a score dividing three groups: (i) negative (E-/-); (ii) heterogeneous (E-/+); and (iii) homogeneous (E+/+). The groups were further analysed with regard to time-to-recurrence (TTR) and recurrence-free-survival (RFS). RESULTS: We included 314 tumor spots from 69 patients (76.8% male, median age 66, liver cirrhosis/fibrosis 75.8%). The risk factors were alcohol abuse (26.2%), NASH (13.1%), HBV (15.5%), HCV (17.9%) and others (27.4%), representative of a typical Western cohort. E+/+ patients experienced significantly shorter TTR and RFS compared to E+/- and E-/- patients (TTR 5 vs. 19 months, p = 0.022; RFS 5 vs. 14 vs. 21 months, p = 0.016). Only homogeneous EpCAM-positivity correlated with higher AFP levels (> 400 ng/ml, p = 0.031). CONCLUSIONS: Spatial heterogeneity of EpCAM-expression was markedly present in the cohort. Of note, only homogeneous EpCAM-expression correlated significantly with early recurrence, whereas heterogeneous EpCAM-expression was associated with clinical endpoints comparable to EpCAM-negativity. We identified a unique HCC subtype associated with a high risk of tumor recurrence.

Targeting the Mutational Landscape of Bystander Cells: Drug-Promoted Blood Cancer From High-Prevalence Pre-neoplasias in Patients on BRAF Inhibitors.

Drug-promoted cancers are increasingly recognized as a serious clinical problem in patients receiving BRAF inhibitory treatment. Here we report on a patient with BRAF mutant hairy cell leukemia and monoclonal B-cell lymphocytosis (MBL), who responded durably to BRAF/MEK inhibitors (BRAFi/MEKi) but experienced transformation of a RAS mutant MBL to chronic lymphocytic leukemia (CLL) with accelerated nodal progression. Hypothesizing that BRAFi triggered excessive MEK-ERK signaling in the MBL/CLL clone via the CRAF/RAS complex as previously described for BRAFi-induced cancers, BRAFi was discontinued inducing a rapid remission of the CLL on MEKi alone. Liquid biopsy monitoring showed a continuous increase of the MBL/CLL clone from the start of BRAFi/MEKi treatment followed by a rapid decline upon BRAFi withdrawal. Next-generation sequencing of a cohort of patients with MBL and monoclonal gammopathy of unclear significance (MGUS) revealed that almost one third of these cases harbored RAS mutations. In view of the population frequency of lymphatic pre-malignant conditions and the prevalence of RAS mutations in such cases, vigilant surveillance remains critical in patients treated with BRAF inhibitors.

Androgens predispose males to monocyte-mediated immunopathology by inducing the expression of leukocyte recruitment factor CXCL1.

Hepatic amebiasis, predominantly occurring in men, is a focal destruction of the liver due to the invading protozoan Entamoeba histolytica. Classical monocytes as well as testosterone are identified to have important functions for the development of hepatic amebiasis in mice, but a link between testosterone and monocytes has not been identified. Here we show that testosterone treatment induces proinflammatory responses in human and mouse classical monocytes. When treated with 5α-dihydrotestosterone, a strong androgen receptor ligand, human classical monocytes increase CXCL1 production in the presence of Entamoeba histolytica antigens. Moreover, plasma testosterone levels of individuals undergoing transgender procedure correlate positively with the TNF and CXCL1 secretion from their cultured peripheral blood mononuclear cells following lipopolysaccharide stimulation. Finally, testosterone substitution of castrated male mice increases the frequency of TNF/CXCL1-producing classical monocytes during hepatic amebiasis, supporting the hypothesis that the effects of androgens may contribute to an increased risk of developing monocyte-mediated pathologies.

Treatment Lines in Hepatocellular Carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and the second most lethal malignancy worldwide. In the Western world, HCC predominantly develops in patients with liver cirrhosis. Therefore, application of locoregional interventions and systemic agents should be based on an interdisciplinary evaluation, most importantly, taking the functional liver reserve into account. This review summarizes current treatment lines and novel strategies in the management of HCC. For the most part, randomized controlled trials and large meta-analyses are reported, with an emphasis on systemic therapies. SUMMARY: In patients with limited hepatic disease and sufficient liver function, resection and local ablation are the most frequently employed curative locoregional therapies. Due to recurrence rates of up to 70% within 5 years and in patients with compromised liver function not amenable to these local modalities, liver transplantation remains superior in terms of tumor control and long-term survival. However, its applicability is limited because of the increasing gap between available donor organs and patients on the waiting list. Transarterial chemoembolization is commonly employed to bridge patients to transplantation and also serves as standard of care for patients not suitable for other local therapies. Recently, various phase 3 trials have reported a clinical benefit for the tyrosine kinase inhibitors lenvatinib, regorafenib, and cabozantinib in HCC. In addition, ramucirumab, an angiostatic antibody, also improves survival in second-line systemic therapy. This opens new avenues in the sequential application of treatment lines, and thus early response assessment is necessary to fully utilize the clinical impact of locoregional therapies and systemic therapies and to shift patients to further treatment lines before hepatic deterioration. KEY MESSAGES: Clinical decision-making in hepatocellular carcinoma is based on an interdisciplinary evaluation. Liver transplantation should always be considered as long-term curative treatment option, especially in T2 patients. In palliative treatment, early response assessment is required to advance patients to the next treatment line before decompensation.

Liver infiltrating T cells regulate bile acid metabolism in experimental cholangitis.

BACKGROUND & AIMS: T cells are central mediators of liver inflammation and represent potential treatment targets in cholestatic liver disease. Whereas emerging evidence shows that bile acids (BAs) affect T cell function, the role of T cells for the regulation of BA metabolism is unknown. In order to understand this interplay, we investigated the influence of T cells on BA metabolism in a novel mouse model of cholangitis. METHODS: Mdr2-/- mice were crossed with transgenic K14-OVAp mice, which express an MHC class I restricted ovalbumin peptide on biliary epithelial cells (Mdr2-/-xK14-OVAp). T cell-mediated cholangitis was induced by the adoptive transfer of antigen-specific CD8+ T cells. BA levels were quantified using a targeted liquid chromatography-mass spectrometry-based approach. RESULTS: T cell-induced cholangitis resulted in reduced levels of unconjugated BAs in the liver and significantly increased serum and hepatic levels of conjugated BAs. Genes responsible for BA synthesis and uptake were downregulated and expression of the bile salt export pump was increased. The transferred antigen-specific CD8+ T cells alone were able to induce these changes, as demonstrated using Mdr2-/-xK14-OVAp recipient mice on the Rag1-/- background. Mechanistically, we showed by depletion experiments that alterations in BA metabolism were partly mediated by the proinflammatory cytokines TNF and IFN-γ in an FXR-dependent manner, a process that in vitro required cell contact between T cells and hepatocytes. CONCLUSION: Whereas it is known that BA metabolism is dysregulated in sepsis and related conditions, we have shown that T cells are able to control the synthesis and metabolism of BAs, a process which depends on TNF and IFN-γ. Understanding the effect of lymphocytes on BA metabolism will help in the design of combined treatment strategies for cholestatic liver diseases. LAY SUMMARY: Dysregulation of bile acid metabolism and T cells can contribute to the development of cholangiopathies. Before targeting T cells for the treatment of cholangiopathies, it should be determined whether they exert protective effects on bile acid metabolism. Herein, we demonstrate that T cell-induced cholangitis resulted in decreased levels of harmful unconjugated bile acids. T cells were able to directly control synthesis and metabolism of bile acids, a process which was dependent on the proinflammatory cytokines TNF and IFN-γ. Understanding the effect of lymphocytes on bile acid metabolism will help in the design of combined treatment strategies for cholestatic liver diseases.

Patient radiation dose in percutaneous biliary interventions: recommendations for DRLs on the basis of a multicentre study.

OBJECTIVE: Percutaneous biliary interventions (PBIs) can be associated with a high patient radiation dose, which can be reduced when national diagnostic reference levels (DRLs) are kept in mind. The aim of this multicentre study was to investigate patient radiation exposure in different percutaneous biliary interventions, in order to recommend national DRLs. METHODS: A questionnaire asking for the dose area product (DAP) and the fluoroscopy time (FT) in different PBIs with ultrasound- or fluoroscopy-guided bile duct punctures was sent to 200 advanced care hospitals. Recommended national DRLs are set at the 75th percentile of all DAPs. RESULTS: Twenty-three facilities (9 interventional radiology depts. and 14 gastroenterology depts.) returned the questionnaire (12%). Five hundred sixty-five PBIs with 19 different interventions were included in the analysis. DAPs (range 4-21,510 cGy·cm2) and FTs (range 0.07-180.33 min) varied substantially depending on the centre and type of PBI. The DAPs of initial PBIs were significantly (p < 0.0001) higher (median 2162 cGy·cm2) than those of follow-up PBIs (median 464 cGy·cm2). There was no significant difference between initial PBIs with ultrasound-guided bile duct puncture (2162 cGy·cm2) and initial PBIs with fluoroscopy-guided bile duct puncture (2132 cGy·cm2) (p = 0.85). FT varied substantially (0.07-180.33 min). CONCLUSIONS: DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. PBI with US-guided bile duct puncture did not reduce DAP, when compared to PBI with fluoroscopy-guided bile duct puncture. National DRLs of 4300 cGy·cm2 for initial PBIs and 1400 cGy·cm2 for follow-up PBIs are recommended. KEY POINTS: • DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. • PBI with US-guided bile duct puncture did not reduce DAP when compared to PBI with fluoroscopy-guided bile duct puncture. • DRLs of 4300 cGy·cm2for initial PBIs (establishing a transhepatic tract) and 1400 cGy·cm2for follow-up PBIs (transhepatic tract already established) are recommended.

Early heme oxygenase 1 induction delays tumour initiation and enhances DNA damage repair in liver macrophages of Mdr2-/- mice.

Multi drug resistance protein 2 knockout mice (Mdr2-/-) are a mouse model of chronic liver inflammation and inflammation-induced tumour development. Here we investigated the kinetics of early heme oxygenase 1 (HO-1) induction on inflammation, tumour development, and DNA damage in Mdr2-/- mice. HO-1 was induced by intraperitoneal injection of cobalt protoporphyrin IX (CoPP) twice weekly for 9 consecutive weeks. Immediately after HO-1 induction, liver function improved and infiltration of CD4+ and CD8+ T cells was reduced. Furthermore, we observed increased p38 activation with concomitant reduction of Cyclin D1 expression in aged Mdr2-/- mice. Long-term effects of HO-1 induction included increased CD8+ T cell infiltration as well as delayed and reduced tumour growth in one-year-old animals. Unexpectedly, DNA double-strand breaks were detected predominantly in macrophages of 65-week-old Mdr2-/- mice, while DNA damage was reduced in response to early HO-1 induction in vivo and in vitro. Overall, early induction of HO-1 in Mdr2-/- mice had a beneficial short-term effect on liver function and reduced hepatic T cell accumulation. Long-term effects of early HO-1 induction were increased CD8+ T cell numbers, decreased proliferation as wells as reduced DNA damage in liver macrophages of aged animals, accompanied by delayed and reduced tumour growth.

Transarterial chemoembolization versus sorafenib in patients with hepatocellular carcinoma and extrahepatic disease.

BACKGROUND: Sorafenib is the recommended treatment for advanced hepatocellular carcinoma (HCC), but transarterial chemoembolization (TACE) is performed in individual cases with limited extrahepatic spread. The aim of this study was to compare the outcome of patients with HCC and extrahepatic disease (EHD) treated with sorafenib and TACE. METHODS: A total of 172 patients with HCC and EHD treated with sorafenib (n = 98) or TACE (n = 74) at three German referral centers (Hannover, Mainz and Hamburg) were included in this study. In order to reduce selection bias, patients were matched for significant demographic differences using a propensity score analysis. RESULTS: Patients with liver cirrhosis, higher extrahepatic tumor burden and/or infiltration of adjacent organs/structures were significantly more often treated with sorafenib. Median overall survival (OS) was similar for sorafenib- and TACE-treated patients (7 versus 8 months, p = 0.312). In a propensity score analysis matched for demographic differences, median OS remained similar with 4 versus 8 months for sorafenib versus TACE (p = 0.613). CONCLUSION: Treatment with TACE is not inferior to treatment with sorafenib in patients with limited EHD of HCC. TACE represents an effective therapeutic option in selected patients with EHD.

Endoscopy versus radiology in post-procedural monitoring after peroral endoscopic myotomy (POEM).

BACKGROUND: The newly developed technique of peroral endoscopic myotomy (POEM) has been shown to be effective in several short- and mid-term studies. Limited information is available about the adequacy of immediate post-POEM monitoring tests. METHODS: POEM was performed under general anesthesia in 228 patients (59.6% male, mean age 45.6 ± 15.5 years). Post-procedural checks comprised clinical and laboratory examination, and, during post-procedure days 1-5, endoscopy and-in the first 114 cases-radiologic examination using water-soluble contrast (1st group); the remaining patients underwent post-procedure controls without radiology (2nd group). Main outcome was value of endoscopic compared to radiologic control for recognition of early adverse events. RESULTS: In the first group, routine fluoroscopic contrast swallow suggested minor leakages at the mucosal entry site in two cases which was confirmed endoscopically in only one. Endoscopy revealed two minor entry site leakages and, in six additional cases, dislocated clips without leakage (overall 5.3%). All eight patients underwent reclipping and healed without clinical sequelae. In the 2nd group, endoscopy showed 5 clip dislocations (all reclipped) and one ischemic cardiac perforation in a patient with clinical deterioration on post-POEM day 1 who had to undergo surgery after confirmation of leakage by CT. CONCLUSIONS: Radiologic monitoring (contrast swallow) after POEM is not useful and can be omitted. Even routine endoscopic monitoring for detection and closure of minor defects of the mucosal entry site yields limited information with regards to final outcome; major complications are very rare and probably associated with clinical deterioration. Clinical Trials Gov Registration number of the main study: NCT01405417.

Towards Picogram Detection of Superparamagnetic Iron-Oxide Particles Using a Gradiometric Receive Coil.

Superparamagnetic iron-oxide nanoparticles can be used in medical applications like vascular or targeted imaging. Magnetic particle imaging (MPI) is a promising tomographic imaging technique that allows visualizing the 3D nanoparticle distribution concentration in a non-invasive manner. The two main strengths of MPI are high temporal resolution and high sensitivity. While the first has been proven in the assessment of dynamic processes like cardiac imaging, it is unknown how far the detection limit of MPI can be lowered. Within this work, we will present a highly sensitive gradiometric receive-coil unit combined with a noise-matching network tailored for the imaging of mice. The setup is capable of detecting 5 ng of iron in-vitro with an acquisition time of 2.14 sec. In terms of iron concentration we are able to detect 156 µg/L marking the lowest value that has been reported for an MPI scanner so far. In-vivo MPI mouse images of a 512 ng bolus and a 21.5 ms acquisition time allow for capturing the flow of an intravenously injected tracer through the heart of a mouse. Since it has been rather difficult to compare detection limits across MPI publications we propose guidelines to improve the comparability of future MPI studies.

The Diagnosis and Treatment of Hemoptysis.

BACKGROUND: Hemoptysis, i.e., the expectoration of blood from the lower airways, has an annual incidence of approximately 0.1% in ambulatory patients and 0.2% in inpatients. It is a potentially life-threatening medical emergency and carries a high mortality. METHODS: This review article is based on pertinent publications retrieved by a selective search in PubMed. RESULTS: Hemoptysis can be a sign of many different diseases. Its cause remains unknown in about half of all cases. Its more common recognized causes include infectious and inflammatory airway diseases (25.8%) and cancer (17.4%). Mild hemoptysis is self-limited in 90% of cases; massive hemoptysis carries a worse prognosis. In patients whose life is threatened by massive hemoptysis, adequate oxygenation must be achieved through the administration of oxygen, positioning of the patient with the bleeding side down (if known), and temporary intubation if necessary. A thorough diagnostic evaluation is needed to identify the underlying pathology, site of bleeding, and vascular anatomy, so that the appropriate treatment can be planned. The evaluation should include conventional chest x-rays in two planes, contrastenhanced multislice computerized tomography, and bronchoscopy. Hemostasis can be achieved at bronchoscopically accessible bleeding sites with interventionalbronchoscopic local treatment. Bronchial artery embolization is the first line of treatment for hemorrhage from the pulmonary periphery; it is performed to treat massive or recurrent hemoptysis or as a presurgical measure and provides successful hemostasis in 75-98% of cases. Surgery is indicated if bronchial artery embolization alone is not successful, or for special indications (traumatic or iatrogenic pulmonary/vascular injury, refractory asper gilloma). CONCLUSION: The successful treatment of hemoptysis requires thorough diagnostic evaluation and close interdisciplinary collaboration among pulmonologists, radiologists, and thoracic surgeons.

TIMP-1 is upregulated, but not essential in hepatic fibrogenesis and carcinogenesis in mice.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is upregulated during hepatic fibrogenesis and considered to promote fibrosis in the injured liver by inhibition of matrix metalloproteases (MMP) and degradation of extracellular matrix. Moreover, TIMP-1 displays anti-apoptotic properties, in patients with hepatocellular carcinoma (HCC) TIMP-1 serum levels are elevated and high TIMP-1 expression levels in HCC are associated with a poor prognosis. Therefore, TIMP-1 could functionally link fibrogenesis and carcinogenesis in the liver. The aim of our study was to characterize the role of TIMP-1 in hepatic fibrogenesis and carcinogenesis. Experimental hepatic fibrogenesis as well as diethylnitrosamine (DEN) -induced hepatocarcinogenesis were studied in TIMP-1-deficient mice and wild type littermates. Hepatic TIMP-1 expression was upregulated following induction of liver fibrosis by bile duct ligation (BDL) or by carbon tetrachloride (CCl4). Unexpectedly, in comparison to wild type littermates, TIMP-1-deficient mice were not protected from liver fibrosis induced by BDL or CCl4. TIMP-1 expression was significantly higher in HCC nodules than in surrounding liver tissue. However, experimental hepatic carcinogenesis was similar in TIMP-1-deficient mice and wild type littermates following DEN-treatment or combined treatment with DEN and CCl4. Therefore we concluded that TIMP-1 is not essential for hepatic fibrogenesis and carcinogenesis in mice.

Exceedingly small iron oxide nanoparticles as positive MRI contrast agents.

Medical imaging is routine in the diagnosis and staging of a wide range of medical conditions. In particular, magnetic resonance imaging (MRI) is critical for visualizing soft tissue and organs, with over 60 million MRI procedures performed each year worldwide. About one-third of these procedures are contrast-enhanced MRI, and gadolinium-based contrast agents (GBCAs) are the mainstream MRI contrast agents used in the clinic. GBCAs have shown efficacy and are safe to use with most patients; however, some GBCAs have a small risk of adverse effects, including nephrogenic systemic fibrosis (NSF), the untreatable condition recently linked to gadolinium (Gd) exposure during MRI with contrast. In addition, Gd deposition in the human brain has been reported following contrast, and this is now under investigation by the US Food and Drug Administration (FDA). To address a perceived need for a Gd-free contrast agent with pharmacokinetic and imaging properties comparable to GBCAs, we have designed and developed zwitterion-coated exceedingly small superparamagnetic iron oxide nanoparticles (ZES-SPIONs) consisting of ∼3-nm inorganic cores and ∼1-nm ultrathin hydrophilic shell. These ZES-SPIONs are free of Gd and show a high T1 contrast power. We demonstrate the potential of ZES-SPIONs in preclinical MRI and magnetic resonance angiography.

Multi-color RGB marking enables clonality assessment of liver tumors in a murine xenograft model.

We recently introduced red-green-blue (RGB) marking for clonal cell tracking based on individual color-coding. Here, we applied RGB marking to study clonal development of liver tumors. Immortalized, non-tumorigenic human fetal hepatocytes expressing the human telomerase reverse transcriptase (FH-hTERT) were RGB-marked by simultaneous transduction with lentiviral vectors encoding mCherry, Venus, and Cerulean. Multi-color fluorescence microscopy was used to analyze growth characteristics of RGB-marked FH-hTERT in vitro and in vivo after transplantation into livers of immunodeficient mice with endogenous liver damage (uPA/SCID). After initially polyclonal engraftment we observed oligoclonal regenerative nodules derived from transplanted RGB-marked FH-hTERT. Some mice developed monochromatic invasive liver tumors; their clonal origin was confirmed both on the molecular level, based on specific lentiviral-vector insertion sites, and by serial transplantation of one tumor. Vector insertions in proximity to the proto-oncogene MCF2 and the transcription factor MITF resulted in strong upregulation of mRNA expression in the respective tumors. Notably, upregulated MCF2 and MITF expression was also observed in 21% and 33% of 24 human hepatocellular carcinomas analyzed. In conclusion, liver repopulation with RGB-marked FH-hTERT is a useful tool to study clonal progression of liver tumors caused by insertional mutagenesis in vivo and will help identifying genes involved in liver cancer.