Ultrasound-guided intracardial injection and in vivo magnetic resonance imaging of single cells in mice as a paradigm for hematogenous metastases

Magnetic resonance imaging (MRI) has become an important technique for noninvasive cell tracking in preclinical research. Following appropriate cell labeling MRI can be used to detect larger cell cohorts and also single cells in vivo in mice. Cell distribution to different organs such as brain, liver, spleen, and kidneys can be visualized, semi-quantified, and followed over time. Thus, the fate of single tumor cells and their eventual development to solid metastases could be investigated. Mesenchymal stromal cells can be used as a paradigm for metastasizing tumor cells. We have demonstrated a strategy for magnetic and fluorescent co-labeling of mesenchymal stromal cells (MSC), ultrasound-guided intracardial cell injection with efficient systemic cell delivery, and high-resolution MRI for repetitive visualization of disseminated co-labeled MSC on a single-cell level in vivo in mice. Furthermore, the fluorescent labeling of cells enabled effective histopathological validation.

18F-FDG PET/CT for detection of malignant peripheral nerve sheath tumours in neurofibromatosis type 1: tumour-to-liver ratio is superior to an SUVmax cut-off

OBJECTIVES

To evaluate the usefulness of normalising intra-tumour tracer accumulation on (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to reference tissue uptake for characterisation of peripheral nerve sheath tumours (PNSTs) in neurofibromatosis type 1 (NF1) compared with the established maximum standardised uptake value (SUVmax) cut-off of >3.5.

METHODS

Forty-nine patients underwent FDG PET/CT. Intra-tumour tracer uptake (SUVmax) was normalised to three different reference tissues (tumour-to-liver, tumour-to-muscle and tumour-to-fat ratios). Receiver operating characteristic (ROC) analyses were used out to assess the diagnostic performance. Histopathology and follow-up served as the reference standard.

RESULTS

Intra-tumour tracer uptake correlated significantly with liver uptake (rs= 0.58, P = 0.016). On ROC analysis, the optimum threshold for tumour-to-liver ratio was >2.6 (AUC = 0.9735). Both the SUVmax cut-off value of >3.5 and a tumour-to-liver ratio >2.6 provided a sensitivity of 100 %, but specificity was significantly higher for the latter (90.3% vs 79.8%; P = 0.013).

CONCLUSIONS

In patients with NF1, quantitative (18)F-FDG PET imaging may identify malignant change in neurofibromas with high accuracy. Specificity could be significantly increased by using the tumour-to-liver ratio. The authors recommend further evaluation of a tumour-to-liver ratio cut-off value of >2.6 for diagnostic intervention planning.

KEY POINTS

• (18)F-FDG PET/CT is used for detecting malignancy in PNSTs in NF1 patients • An SUV max cut-off value may give false-positive results for benign plexiform neurofibromas • Specificity can be significantly increased using a tumour-to-liver ratio.

Selectin binding is essential for peritoneal carcinomatosis in a xenograft model of human pancreatic adenocarcinoma in pfp--/rag2-- mice

BACKGROUND AND OBJECTIVE

E- and P-selectins expressed on the luminal surface of mesodermally derived endothelial cells play a crucial role in the formation of haematogenous metastases in a number of malignancies. As peritoneal mesothelial cells are also derived form the mesoderm, it was hypothesised that selectins are also of importance in peritoneal tumour spread.

METHODS

Immunohistochemistry was used to identify selectin expression on normal human peritoneum and isolated mesothelial cells. E- and P-selectin interactions with human pancreatic adenocarcinoma cells were investigated in dynamic flow assays and flow cytometry; the latter was also used to determine the main selectin ligands on pancreatic adenocarcinoma cell lines PaCa 5061, BxPC-3 and PaCa 5072, and selectin expression on human mesothelial cells. All cell lines were xenografted into the peritoneum of E- and P-selectin-deficient pfp/rag2 mice and selectin wild-type controls. Peritoneal carcinomatosis was quantified using MRI or a scoring system.

RESULTS

E- and P-selectin were constitutively expressed on human mesothelial and endothelial cells in the peritoneum. PaCa 5061 and BxPC-3 cells interacted with E- and P-selectins in dynamic flow assays and flow cytometry, with CA19-9 (Sialyl Lewis a) being the main E-selectin ligand. For xenografted PaCa 5061 and BxPC-3 cells, peritoneal metastasis was significantly reduced in E- and P-selectin double knockout mice compared with wild-type pfp/rag2 animals. In contrast, PaCa 5072 cells were almost devoid of selectin binding sites and no intraperitoneal tumour growth was observed.

CONCLUSION

Interactions of tumour cells with peritoneal selectins play an important role in the peritoneal spread of pancreatic adenocarcinoma.

Interaction of magnetically labeled multipotent mesenchymal stromal cells and E-and P-selectins monitored by magnetic resonance imaging in mice

The purpose of this study was to analyze the influence of E- and P-selectins on the migratory pattern of magnetically labeled multipotent mesenchymal stromal cells (MSCs) in mice using magnetic resonance imaging (MRI). Murine MSCs were labeled with fluorescent iron oxide microparticles and carboxyfluorescein succinidyl ester (CFSE). Expression of common MSC markers, CD44, CD90, CD105, and Sca-1, as well as of selectin ligands, CD15s and CD162, was assessed using flow cytometry and immunocytochemistry. Labeled MSCs were injected into E-/P-selectin-deficient and wild-type mice applying doses of 5 × 10(4) cells intracardially, 1 × 10(6) cells intravenously, and 5 × 10(6) cells intraperitoneally. After cell administration, mice underwent MRI repeatedly and histologic evaluation after 7 days. The results demonstrate that magnetically labeled murine MSCs retain their expression of the above-mentioned surface markers and their ability to interact with P-selectin. Furthermore, MRI examinations and histologic analysis revealed that E-/P-selectin deficiency in mice significantly alters the distribution of labeled MSCs after cell injection via different routes.

Evaluation of intratumoural heterogeneity on ¹⁸F-FDG PET/CT for characterization of peripheral nerve sheath tumours in neurofibromatosis type 1

PURPOSE

The aim of the study was to evaluate the potential usefulness of intratumoural tracer uptake heterogeneity on (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT as compared to a cut-off maximum standardized uptake value (SUVmax) for characterization of peripheral nerve sheath tumours (PNSTs) in neurofibromatosis type 1 (NF1).

METHODS

Fifty patients suffering from NF1 were examined by (18)F-FDG PET/CT. Intralesional tracer uptake was analysed qualitatively and semi-quantitatively by measuring the mean and maximum SUV. Uptake heterogeneity was graded qualitatively using a three-point scale and semi-quantitatively by calculating an SUV-based heterogeneity index (HISUV). Cohen's κ was used to determine inter- and intra-rater agreement. Histopathological evaluation and clinical as well as radiological follow-up examinations served as the reference standards.

RESULTS

A highly significant correlation between the degree of intratumoural uptake heterogeneity on (18)F-FDG PET and malignant transformation of PNSTs was observed (p < 0.0001). Semi-quantitative HISUV was significantly higher in malignant PNSTs (MPNSTs) than in benign tumours (p = 0.0002). Both intralesional heterogeneity and SUVmax could be used to identify malignant tumours with a sensitivity of 100 %. Cohen's κ was 0.86 for inter-rater agreement and 0.88 for intra-rater agreement on heterogeneity.

CONCLUSION

MPNSTs in patients with NF1 demonstrate considerable intratumoural uptake heterogeneity on (18)F-FDG PET/CT. Assessment of tumour heterogeneity is highly reproducible. Both tumour heterogeneity and a cut-off SUVmax may be used to sensitively identify malignant PNSTs, but the specificity is higher for the latter. A combination of both methods leads to a non-significant improvement in diagnostic performance.

Tailor-made quantum dot and iron oxide based contrast agents for in vitro and in vivo tumor imaging

The biofunctionalization of CdSe/CdS/ZnS quantum dots and Fe(3)O(4) nanocrystals using a novel ligand system based on polyisoprene-block-poly(ethylene oxide) ligands is described. The synthesis includes a partial ligand exchange of the hydrophobic nanocrystals with amino-functionalized polyisoprene ligands, followed by seeded micelle formation of the diblock-copolymers in water. The resulting water-soluble quantum dots showed fluorescence quantum efficiencies in the 40 to 50% range and extraordinary fluorescence stability in the biological environment after cross-linking of the polyisoprene moiety of the ligand shell. No toxicity was detected by water-soluble tetrazolium (WST8) and lactate dehydrogenase (LDH) assays, even at very high nanoparticle concentrations, and almost no nonspecific cell adhesion was detected. The ligand shell was further coupled to the antigen-related cell adhesion molecule (CEACAM) specific monoclonal antibody T84.1. The so-conjugated Fe(3)O(4) nanocrystals allowed in vitro and in vivo tumor targeting by magnetic resonance imaging.

Neonatal hippocampal lesion alters the functional maturation of the prefrontal cortex and the early cognitive development in pre-juvenile rats

Mnemonic and executive performance is encoded into activity patterns of complex neuronal networks. Lesion studies revealed that adult recognition memory critically depends on the activation of the prefrontal cortex (PFC) and hippocampus (HP). However, its developmental profile remains poorly elucidated. We previously showed the rat PFC and HP are functionally coupled in theta- and gamma-band oscillations during neonatal [postnatal day (P) 5-8] and pre-juvenile (P10-15) stages of development. Here, we assess the behavioral readout of this early prefrontal-hippocampal activation by investigating the ontogeny and the mechanisms of novelty detection and recognition memory in relationship to the functional integrity of the PFC and HP. Excitotoxic lesion of the HP at birth led to abnormal oscillatory entrainment of the PFC throughout neonatal and pre-juvenile development. Although the onset of novelty detection correlated rather with the maturation of sensory perception and motor skills than with hippocampal integrity, the pre-juvenile performance in item, spatial and temporal order recognition memory significantly decreased after HP lesion at birth. This poorer performance does result neither from abnormal developmental milestones and locomotion nor from increased anxiety. Thus, novelty recognition in rat emerges during the second postnatal week and requires functional integrity of communication within neuronal networks including the PFC and HP.

Hematopoietic recovery after IEV chemotherapy for malignant lymphoma followed by different cytokines can be monitored by analysis of Galpha 16 and CD34

The hematopoiesis-specific G protein alpha subunit Galpha16 is a specific element in the signal transduction of the early hematopoietic cytokine network. As Galpha16 mRNA can be detected in early hematopoietic progenitor cells, RT-PCR for Galpha16 can be used as a sensitive marker of hematopoietic activity. The aim of this study was to test the possible use of Galpha16 determinations for monitoring cytokine effects on hematopoietic recovery after chemotherapy in patients. We correlated presence of Galpha16 mRNA and CD34 surface antigen with hematopoietic recovery in six lymphoma patients undergoing salvage therapy with different cytokine support (IEV followed by G-CSF, IL-3, or placebo). Regardless of different cytokine schedules with different time courses, hematopoietic recovery was always preceded by transcription of Galpha16. Monitoring the expression of Galpha16 mRNA by RT-PCR is a highly sensitive diagnostic tool for analyzing hematopoietic recovery after chemotherapy and for characterizing the effects of cytokines on hematopoiesis.

In vivo and in vitro effects of cytokines and the hemoregulatory peptide dimer (pEEDCK)2 (pyroGlu-Glu-Asp-Cys-Lys)2 on G alpha16-positive hematopoiesis

G proteins play an important role in signal transduction from cytokine receptors to intracellular effectors via different pathways, eg involving tyrosine kinases. In our previous studies, we demonstrated that mRNA expression of the hematopoiesis-specific G protein alpha-subunit G alpha16 is a sensitive marker indicating the appearance of early myeloid and lymphoid progenitors. This study was designed to investigate cytokine effects on hematopoiesis in vivo and in vitro as reflected by G alpha16 expression and sensitivity to the hemoregulatory peptide (pEEDCK)2 which harbors a structural homology to the effector domain of G alpha16. Investigations on blood samples from lymphoma patients undergoing salvage therapy with different cytokine support showed that monitoring of the expression of G alpha16 mRNA which appears to play a role in cytokine signalling via tyrosine kinases was a valuable complementation to CD34 screening for analyzing hematopoietic recovery after chemotherapy. We demonstrated that in contrast to CD34 which is only expressed in quiescent cells, G alpha16 transcription occurs independently of cell cycle state. In vitro, we could show that G alpha16 was also a valuable marker for confirming the immature state of ex vivo expanded blood stem cells from patients. A further part of the study was focused on the response of G alpha16 and CD34 expressing cells to the granulocyte-derived hemoregulatory peptide (pyroGlu-Glu-Asp-Cys-Lys)2 = (pEEDCK)2 which harbors a G alpha16-homologous sequence motif. Results obtained from in vitro assays which involved estimation of colony outgrowth from CD34-positive cells showed that the effect of (pEEDCK)2 on CD34 cells enhanced the effect of IL-3 or SCF. These data indicate that G alpha16 may co-operate with (pEEDCK)2 in triggering the cytokine response of immature hematopoietic cells.

Monitoring of hematopoietic recovery after autologous stem cell transplantation by analysis of G alpha 16 mRNA and CD34 surface glycoprotein

The hematopoiesis-specific G protein alpha subunit G alpha16 was shown to be expressed in early normal and malignant hematopoietic cell lines and has been suggested to play an important role in signal transduction of hematopoiesis. We previously demonstrated a strict correlation of G alpha16 mRNA and CD34 antigen expression in peripheral blood stem cells (PBSC). In PBSC mobilization, both markers are detectable at the time of hematopoietic recovery and progenitor cell release. In this study the possible use of G alpha16 determination in peripheral blood samples for monitoring patients undergoing stem cell transplantation was investigated. Normal peripheral blood is negative for G alpha16 expression. In all five patients G alpha16 mRNA expression appeared shortly before the time of blood cell recovery. When tested together with CD34 (three cases) a pattern different from CD34 antigen expression was found, reflecting a different mechanism of action. In two cases with different time points of leukocyte and platelet recovery G alpha16 mRNA was detected at both time points but not in the interval, thus suggesting a role of G alpha16 in multipotent precursor cells. CD34 mRNA tested in three patients was not detected at any time; this argues for different regulation of CD34 and G alpha16 mRNA. G alpha16 may be used as an indicator of hematopoietic recovery after autologous stem cell transplantation, suggesting that there are cell type-specific G protein-mediated signal transduction pathways of early hematopoiesis.

Stimulation of the central and peripheral nervous system for the control of pain

After suffering some setbacks since its introduction in 1967, stimulation of the spinal and peripheral nervous systems has undergone rapid development in the last ten years. Based on principles enunciated in the Gate Control Hypothesis that was published in 1968, stimulation-produced analgesia [SPA] has been subjected to intensive laboratory and clinical investigation. Historically, most new clinical ideas in medicine have tended to follow a three-tiered course. Initial enthusiasm gives way to a reappraisal of the treatment or modality as side-effects or unanticipated problems arise. The last and third phase proceeds at a more measured pace as the treatment is refined by experience. This review is divided into three parts as it traces the progress of spinal cord stimulation [SCS] and peripheral nerve stimulation [PNS]. The review commences with a discussion of the theory of SCS and PNS, and is followed by early reports during which it became apparent that the modality is essentially only effective in the treatment of neuropathic pain. The last section describes the modern experience including efficacy in specific types of pain and concludes with recent accomplishments that dramatize the relief of pain which can be achieved in nonoperable peripheral vascular disease or myocardial ischemia. Over the years, a search for those transmitters that might be influenced by spinal cord stimulation focused on somatostatin, cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), neurotensin and other amines, although only substance "P" was implicated. More recently, in animal studies, evidence that GABA-ergic systems are affected may explain the frequent successful suppression of allodynia that follows spinal cord stimulation. During the past eight years, much attention has been directed to studies that use a chronic neuropathic pain model. While PNS held significant promise as a pain relieving modality, early electrode systems and their surgical implantation yielded variable results due to evolving technical and surgical skills. These results dramatically reduced the continued development of PNS, which then gave way to a preoccupation with SCS. Modern development of SCS with outcome studies, particularly in relation to failed back surgery syndrome [FBSS] and the outcome of peripheral nerve surgery for chronic regional pain syndromes, has earned both modalities a place in the ongoing management of patients with intractable neuropathic pain. The last section, dealing with pain of peripheral vascular and myocardial ischemia, is perhaps one of the more exciting developments in stimulation produced analgesia and as the papers discussed demonstrate, can provide a level of analgesia and efficacy that is unattainable by other treatment modalities. SCS and PNS has an important role to play in the management of conditions that are otherwise refractory to conservative or other conventional management.

Expression of G alpha 16, a G-protein alpha subunit specific for hematopoiesis in acute leukemia

G-proteins are essential in signal transduction pathways. A G-protein alpha subunit termed G alpha 16 was found to be exclusively expressed in hematopoietic cell lines. In cells derived from patients, G alpha 16 expression has been detected in progenitor- and pre-B ALL cells and also in peripheral blood stem cells (PBSC). In this study, we analyzed G alpha 16 expression using a RT-PCR technique by testing elutriated blood cells from normal donors, PBSC from breast cancer patients and bone marrow or peripheral blood cells from acute leukemia patients. Both of two ALL patients and 15/16 AML patients expressed G alpha 16. In elutriation experiments, G alpha 16 expression was found in fractions containing the highest number of precursor cells but was absent in mature T and B cell fractions. In addition, CD34-enriched PBSC were positive for G alpha 16 expression. Further in vitro experiments using the cell line KG1 showed that G alpha 16 expression was not affected by the growth inhibiting hemoregulatory peptide pEEDCK which has a sequence homology present within G alpha 16. Taken together, these data demonstrate that G alpha 16 is expressed in various normal and malignant hematopietic progenitors but not in their differentiated counterparts. G alpha 16 could play a vital role in signal transduction pathways controlling proliferation in early normal and malignant hematopoiesis.

Analysis of peripheral blood progenitor cells demonstrates limitations of minimal residual disease diagnosis in a case of acute promyelocytic leukemia

Detection of minimal residual disease (MRD) by analysis of the PML-RAR alpha fusion transcript using the RT-PCR method is routinely carried out on peripheral blood and bone marrow of patients with APL (AML, FAB:M3). Therapy aims to achieve repeated negative results in these patients thus confirming clinical complete remission. We report a case of APL in second complete remission in which no leukemic cells had been detected in BM and PB for 20 months, and in which PBPC-pheresis was carried out for future transplantation. In two of five pheresis PML-RAR alpha fusion transcripts were detected. This shows that the residual leukemic population may only reach detection level after enrichment by PBPC-pheresis.

B lymphocytes with latent EBV infection appearing in long-term bone marrow cultures (HLTBMCs) from haematological patients induce lysis of stromal microenvironment

Human long-term bone marrow cultures (HLTBMCs) are a valuable in vitro model for studying the role of the haemopoietic microenvironment. Here we report the spontaneous appearance of EBV-positive B cells in 6/40 HLTBMCs from patients with various haematological diseases after 3-5 months of culture. After subcultivation of these cells, a novel type of cell line could be characterized, which displayed surface markers and morphological features typical for EBV transformed B-cell lines. As the deproteinized and ultrafiltrated culture supernatants of these cell lines were found to contain an agent with stroma toxic properties, they were termed SSB lines (stroma-toxic-agent-secreting B-cell lines). This agent also exhibited a colony-inhibitory activity on in vitro myelopoiesis and erythropoiesis. These properties are typical for the two polyamines spermine and spermidine which were detected at elevated levels in the culture supernatants of SSB lines. The hypothesis that latent presence of EBV in bone marrow may induce an increased synthesis of spermine and spermidine, which are known to be associated with malignant haematological diseases and bone marrow aplasia, is discussed.

Microscopic venous infiltration as predictor of relapse in renal cell carcinoma

In a retrospective analysis at a single institution we evaluated the significance of various pathological phenomena on the disease-free survival of patients with radically resected renal cell carcinoma. Parameters considered were tumor extension (pT stage) according to the International Union Against Cancer, tumor invasion into the renal vein or vena cava (V stage), standard histological grading (G stage), nuclear grading (F stage) and microscopic venous infiltration. The pT stage had a significant impact on disease-free survival (p = 0.0004) of patients with radically resected tumors, as did G stage (p = 0.0001) and F stage (p = 0.002). In contrast to some previously reported results tumor extension to the renal vein and vena cava showed no influence on disease-free survival (p = 0.077). On the other hand, microscopic venous infiltration, defined as local tumor infiltration through all vessel structures including the endothelial layer leading to a free tumor extension into the vessel, had a significant impact on disease-free survival (p less than 0.0001). When stratifying either tumor size or nuclear differentiation against microscopic venous infiltration, the latter retained a superior influence on disease-free survival (p = 0.01 and p = 0.0079, respectively). We conclude that microscopic venous infiltration is the most important predictor of relapse in renal cell carcinoma.

[Vasovasostomy after vasectomy. The surgical results 1986-1989]

The frequency of vasovasostomy has increased dramatically in recent years. A significant percentage of men who have previously undergone vasectomy are now seeking restoration of their fertility. The most common reason for requesting a reversal is remarriage. There were 90 bilateral vasovasostomies performed in 90 patients between 1986 and 1989. The procedure was done according to the technique described by Howards, in a single layer with 7 x 0 prolene and under fourfold magnification. The success rate was 87% for presence of spermatozoa in the ejaculate, 48% for pregnancy. The fertility rate decreases slowly with increasing interval between vasectomy and reanastomosis. These results are statistically significant. In cases of good anatomical and andrological conditions, the chance of restoration of fertility is good. The experience of the urologist is often more important than the details of the technique.

Concordant changes of pyrimidine metabolism in blasts of two cases of acute myeloid leukemia after repeated treatment with ara-C in vivo

Though data from cell lines are abundant, the reason for the development of resistance to 1-beta-D arabinofuranosylcytosine (ara-C) in vivo remains unresolved. A broad interpatient variation of metabolic parameters has further complicated interpretation of the results. The present study compares ara-C metabolism in leukemic blasts of two patients with newly diagnosed disease, before and after repeated treatment with ara-C containing chemotherapy regimens in vivo. Membrane transport of ara-C was unchanged after treatment. In addition, cell-free extracts of blasts obtained after treatment failure showed an unchanged cytidine deaminase activity. Though deoxycytidine kinase activity in cell extracts was unaltered or increased after treatment failure, the activity in situ, measured as the rate of 1-beta-D-arabinofuranosylcytosine triphosphate (ara-CTP) formation, was decreased. This could be shown to be due to an expansion of the deoxycytidine triphosphate (dCTP) pool. The severalfold increase in dCTP pool was accompanied by a decrease in thymidine triphosphate (dTTP) pool and correlated with a decrease in deoxycytidylate deaminase (dCMP-deaminase) activity in cell free extracts. Low dCMP-deaminase activity had been shown to confer an ara-C resistant phenotype to cell lines in vitro. Data presented in this paper show that a selection for leukemic blasts with low dCMP-deaminase activity can also be favored by ara-C containing treatment regimens in vivo. Our data suggest that this mechanism might contribute to treatment failure.

A microtiter plate technique for the detection of platelet antibodies and platelet antigen typing

A microtiter plate assay is described for platelet serologic studies. The assay is based on an indirect radiolabeled antiglobulin test. The test was performed in microtiter wells of 400 microliter capacity manufactured to form strips that fit into a standard 96-well carrier. The strips were broken apart and placed into tubes for counting in a gamma counter. The technique does not require fixation of the platelets to the wells. Freshly collected platelets or platelets that have been stored frozen in 5 percent dimethylsulfoxide can be used. Results are presented using the technique for platelet alloantibody identification, platelet antigen typing, and platelet crossmatching.