Maintenance of hepatic sinusoidal endothelial cell phenotype in vitro using organ-specific extracellular matrix scaffolds

Sinusoidal endothelial cells (SECs) are notoriously difficult to culture in vitro. SECs represent a highly specialized endothelial cell (EC) population, and traditional methods of SEC isolation from the liver initiate a process of SEC dedifferentiation. Acellular extracellular matrix (ECM) scaffolds were investigated in a physiologically relevant in vitro culture model for their ability to maintain SEC phenotype. The cell culture model used SECs only or a coculture of SECs with hepatocytes on ECM substrates derived from the liver (L-ECM), bladder (UBM-ECM), or small intestine submucosa (SIS-ECM). The effect of the ECM substrate upon SEC dedifferentiation was evaluated using scanning electron microscopy (SEM) and confocal microscopy. When SECs alone were cultured on uncoated glass slides, collagen I, UBM-ECM, or SIS-ECM, SECs showed signs of dedifferentiation after 1 day. In contrast, SECs alone cultured on L-ECM maintained their differentiated phenotype for at least 3 days, indicated by the presence of many fenestrations on SEC surface, expression of anti-rat hepatic sinusoidal endothelial cells mouse IgG MoAb (SE-1), and lack of expression of CD31. When SECs were cocultured with hepatocytes on any of the ECM scaffolds, the SECs maintained a near-normal fenestrated phenotype for at least 1 day. However, SEM revealed that the shape, size, frequency, and organization of the fenestrations varied greatly depending on ECM source. At all time points, SECs cocultured with hepatocytes on L-ECM maintained the greatest degree of differentiation. The present study demonstrated that the acellular ECM scaffold derived from the liver maintained SEC differentiation in culture longer than any of the tested substrate materials. The replacement of complex tissues and 3-dimensional organs may require specialized scaffolds to support multiple, functional cell phenotypes.     

Lymphocyte recruitment to the lung

Lymphocyte recruitment in lymphoid tissues and inflammatory sites occurs in response to two events. The first is adherence of lymphocytes to specialized molecules expressed on the surface of appropriately stimulated vascular endothelial cells known as vascular addressins. The interaction occurs via specialized lymphocyte surface molecules known as homing receptors. There is considerable diversity among these molecules. At least three, and possibly four, different addressin-homing receptor pairs exist, regulating entry into peripheral lymph nodes, gut lymphoid tissue, BALT and intrathoracic lymphoid tissue, and inflamed synovium. Vascular addressins are expressed by specialized endothelial cells known as HEV. HEV are not found in normal lung parenchyma but may be induced to appear during an immune response. The mechanism for induction of HEV is unknown, although it may involve the action of inflammatory cytokines. It is not known whether separate endothelial cells exist with a propensity to develop into HEV or if any endothelial cells will develop into HEV if stimulated in the proper manner. Other accessory, lymphocyte-endothelium adhesion molecule pairs have been described, including LFA-1-ICAM-1 and CD4-HLA-DR. These molecules are induced by exposure of the endothelium to inflammatory cytokines, chiefly IFN-gamma. Thus, local humoral influences present during inflammation can alter the possibility of lymphocyte traffic through the endothelium by regulating the presence of lymphocyte adherence molecules. These processes have been documented to occur in the lung in normal homeostasis (e.g., BALT) and in disease (e.g., immunization with SRBC). After adherence, lymphocytes exit the circulation via amoeboid motility. This motility can be altered and enhanced through chemoattractant substances that act via surface receptors. The biochemical basis of cell motility is not entirely clear but appears to involve a link between the second messengers of receptor signaling and changes in the cytoskeleton, particularly actin filaments and microtubules. Like fibroblasts and smooth muscle cells, lymphocytes appear to respond to a number of "mitoattractants," substances that cause cell cycle entry and/or progression as well as enhanced motility. This relationship illustrates the integral relationship between cell motility and proliferation and suggests that the process of cell recruitment might also prime the recruitment cells to become activated to proliferate and perform effector function. Studies of lymphocyte-mediated lung disease confirm that antigen-specific as well as antigen-nonspecific lymphocytes are selectively recruited to the lung from the circulation during an inflammatory reaction in the lung.(ABSTRACT TRUNCATED AT 400 WORDS)     

Value of a Dixon-based MR/PET attenuation correction sequence for the localization and evaluation of PET-positive lesions

Purpose

In this study, the potential contribution of Dixon-based MR imaging with a rapid low-resolution breath-hold sequence, which is a technique used for MR-based attenuation correction (AC) for MR/positron emission tomography (PET), was evaluated for anatomical correlation of PET-positive lesions on a 3T clinical scanner compared to low-dose CT. This technique is also used in a recently installed fully integrated whole-body MR/PET system.

Methods

Thirty-five patients routinely scheduled for oncological staging underwent ¹⁸F-fluorodeoxyglucose (FDG) PET/CT and a 2-point Dixon 3-D volumetric interpolated breath-hold examination (VIBE) T1-weighted MR sequence on the same day. Two PET data sets reconstructed using attenuation maps from low-dose CT (PET_{AC_CT}) or simulated MR-based segmentation (PET_{AC_MR}) were evaluated for focal PET-positive lesions. The certainty for the correlation with anatomical structures was judged in the low-dose CT and Dixon-based MRI on a 4-point scale (0?C3). In addition, the standardized uptake values (SUVs) for PET_{AC_CT} and PET_{AC_MR} were compared.

Results

Statistically, no significant difference could be found concerning anatomical localization for all 81 PET-positive lesions in low-dose CT compared to Dixon-based MR (mean 2.51?±?0.85 and 2.37?±?0.87, respectively; p?=?0.1909). CT tended to be superior for small lymph nodes, bone metastases and pulmonary nodules, while Dixon-based MR proved advantageous for soft tissue pathologies like head/neck tumours and liver metastases. For the PET_{AC_CT}- and PET_{AC_MR}-based SUVs (mean 6.36?±?4.47 and 6.31?±?4.52, respectively) a nearly complete concordance with a highly significant correlation was found (r?=?0.9975, p?Conclusion Dixon-based MR imaging for MR AC allows for anatomical allocation of PET-positive lesions similar to low-dose CT in conventional PET/CT. Thus, this approach appears to be useful for future MR/PET for body regions not fully covered by diagnostic MRI due to potential time constraints.     

Prognostic value of [<Superscript>18</Superscript>F]FDG-PET/CT in multiple myeloma patients before and after allogeneic hematopoietic cell transplantation

Purpose

Despite improved treatment options, multiple myeloma (MM) remains an incurable disease. The aim of this study was to investigate the prognostic value of positron emission tomography/computed tomography (PET/CT) using ¹⁸F-2’-deoxy-2’-fluorodeoxyglucose ([¹⁸F]FDG) in MM patients shortly before and ~100 days after allogeneic hematopoietic cell transplantation (allo-HCT).

Methods

In this retrospective analysis, we evaluated [¹⁸F]FDG-PET/CT-scans of 45 heavily pre-treated MM patients before and 27 patients after scheduled allo-HCT. All scans were qualitatively and semi-quantitatively assessed for the presence of active disease. Serological response was recorded according to International Myeloma Working Group (IMWG) criteria. Progression-free (PFS) and overall survival (OS) were correlated with different PET/CT-derived parameters, such as presence, number and maximum standardized uptake value (SUV_max) of focal myeloma lesions. The impact of extramedullary disease on patient outcome was also assessed.

Results

PET/CT negativity -prior to or following allo-HCT- was a favorable prognostic factor for progression-free and overall survival (both, PFS and OS: pre-HSCT p?<?0.001, post-HCT p?<?0.005). High FDG-uptake (SUV_max?>?6.5) revealed a significantly shortened survival compared to patients with a lower SUV_max (<6.5) (OS, 5.0?±?1.1 m vs. not reached - longest 122.0 m; p?<?0.001). Moreover, our data prove that a higher number (>3) of focal lesions (pre-HCT: both PFS and OS: p?<?0.001; post-HCT PFS: p?<?0.001, OS: p?=?0.139) as well as the presence of extramedullary disease serve as adverse prognostic factors prior to and after allo-HCT. At response assessment after allo-HCT, [¹⁸F]FDG-PET/CT had a complementary value in prognostication in addition to IMWG criteria alone.

Conclusion

[¹⁸F]FDG-PET/CT before and shortly after allogeneic HCT is a powerful predictor for progression-free and overall survival in MM patients.

     

Brain temperature regulation in poor-grade subarachnoid hemorrhage patients – A multimodal neuromonitoring study

Elevated body temperature (T_core) is associated with poor outcome after subarachnoid hemorrhage (SAH). Brain temperature (T_brain) is usually higher than T_core. However, the implication of this difference (T_delta) remains unclear. We aimed to study factors associated with higher T_delta and its association with outcome. We included 46 SAH patients undergoing multimodal neuromonitoring, for a total of 7879 h of averaged data of T_core, T_brain, cerebral blood flow, cerebral perfusion pressure, intracranial pressure and cerebral metabolism (CMD). Three-months good functional outcome was defined as modified Rankin Scale ≤2. T_brain was tightly correlated with T_core (r = 0.948, p < 0.01), and was higher in 73.7% of neuromonitoring time (T_delta +0.18°C, IQR −0.01 – 0.37°C). A higher T_delta was associated with better metabolic state, indicated by lower CMD-glutamate (p = 0.003) and CMD-lactate (p < 0.001), and lower risk of mitochondrial dysfunction (MD) (OR = 0.2, p < 0.001). During MD, T_delta was significantly lower (0°C, IQR −0.2 – 0.1; p < 0.001). A higher T_delta was associated with improved outcome (OR = 7.7, p = 0.002). Our study suggests that T_brain is associated with brain metabolic activity and exceeds T_core when mitochondrial function is preserved. Further studies are needed to understand how T_delta may serve as a surrogate marker for brain function and predict clinical course and outcome after SAH.     

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

Evaluation of sodium T1 relaxation times in human heart

PURPOSE: To evaluate the sodium longitudinal relaxation (T(1)) characteristics for myocardium and blood in humans. MATERIALS AND METHODS: Eleven healthy volunteers were examined by using a (23)Na heart surface coil at a 1.5 T clinical scanner equipped with a broadband spectroscopy option. (23)Na MR measurements were performed by using a three-dimensional spoiled gradient echo sequence (in-plane resolution, 3.5 mm x 7 mm; slice thickness, 24 mm; TE, 3.1 msec; bandwidth, 65 Hz/pixel; TR, 21 to 150 msec). RESULTS: Longitudinal T(1) relaxation time components were 31.6+/-7.0 msec and 31.1+/-7.5 msec for myocardium and blood, respectively. CONCLUSION: (23)Na T(1) relaxation times of myocardium and blood can be determined in humans. The results are in agreement with values obtained from animal studies.     

Biodistribution and pharmacokinetics of the alphavbeta3-selective tracer 18F-galacto-RGD in cancer patients.

(18)F-Galacto-RGD has been developed for PET of alpha(v)beta(3) integrin expression, a receptor involved in, for example, angiogenesis and metastasis. Our aim was to study the kinetics and biodistribution of (18)F-Galacto-RGD in cancer patients. METHODS: Nineteen patients with metastases of malignant melanoma (n = 7), sarcomas (n = 10), or osseous metastases (n = 2) were examined. After injection of 133-200 MBq (18)F-Galacto-RGD, 3 consecutive emission scans from the pelvis to the thorax or dynamic emission scans of the tumor over 60 min, followed by 1 static emission scan of the body, were acquired. Time-activity curves and standardized uptake values (SUVs) were derived by image region-of-interest analysis with image-based arterial input functions. Compartmental modeling was used to derive the distribution volume for muscle tissue and tumors. RESULTS: (18)F-Galacto-RGD showed rapid blood clearance and primarily renal excretion. SUVs in tumors ranged from 1.2 to 9.0. Tumor-to-blood and tumor-to-muscle ratios increased over time, with peak ratios of 3.1 +/- 2.0 and 7.7 +/- 4.3, respectively, at 72 min. The tumor kinetics were consistent with a 2-tissue compartment model with reversible specific binding. Distribution volume values were, on average, 4 times higher for tumor tissue (1.5 +/- 0.8) than those for muscle tissue (0.4 +/- 0.1). The data suggest that there was only minimal free and bound (specific or nonspecific) tracer in muscle tissue. CONCLUSION: (18)F-Galacto-RGD demonstrates a highly favorable biodistribution in humans with specific receptor binding. Most important, this study shows that (18)F-Galacto-RGD allows visualization of alpha(v)beta(3) expression in tumors with high contrast. Consequently, this tracer offers a new strategy for noninvasive monitoring of molecular processes and may supply helpful information for planning and controlling of therapeutic approaches targeting the alpha(v)beta(3) integrin.     

Classical and anaplastic seminoma: difference in survival

Classical and anaplastic seminoma are traditionally treated with radiation therapy and are said to have the same prognosis. A retrospective study was undertaken of 90 seminoma patients treated with radiation therapy between 1961 and 1985. The classical group consisted of 71 patients of whom 50 had stage I and 21 had stage II disease. The anaplastic group consisted of 19 patients of whom ten had stage I and nine had stage II disease. The median follow-up time was 64 months for the entire group. The 10-year relapse-free survival rate for the classical group was 94% and for the anaplastic group was 70% (P less than .05). For patients with classical stage I disease, the relapse-free actuarial survival rate was 98%; for patients with anaplastic stage I disease, it was 64% (P less than .02). For the classical stage II disease group, the relapse-free actuarial survival rate was 84% and for the anaplastic stage II disease group, 75% (P less than .70). Four patients in the classical group (6%) had relapses; of these, one patient had local recurrence of tumor, and three had distant metastases. In the anaplastic group, four patients (21%) had relapses; two patients had local recurrence of tumor, and two had distant metastases. Therefore the data suggest a difference in survival and relapse rates between classical and anaplastic seminoma.