Sex differences and risk factors for bleeding in Alagille syndrome

Spontaneous bleeds are a leading cause of death in the pediatric JAG1-related liver disease Alagille syndrome (ALGS). We asked whether there are sex differences in bleeding events in patients, whether Jag1^Ndr/Ndr mice display bleeds or vascular defects, and whether discovered vascular pathology can be confirmed in patients non-invasively. We performed a systematic review of patients with ALGS and vascular events following PRISMA guidelines, in the context of patient sex, and found significantly more girls than boys reported with spontaneous intracranial hemorrhage. We investigated vascular development, homeostasis, and bleeding in Jag1^Ndr/Ndr mice, using retina as a model. Jag1^Ndr/Ndr mice displayed sporadic brain bleeds, a thin skull, tortuous blood vessels, sparse arterial smooth muscle cell coverage in multiple organs, which could be aggravated by hypertension, and sex-specific venous defects. Importantly, we demonstrated that retinographs from patients display similar characteristics with significantly increased vascular tortuosity. In conclusion, there are clinically important sex differences in vascular disease in ALGS, and retinography allows non-invasive vascular analysis in patients. Finally, Jag1^Ndr/Ndr mice represent a new model for vascular compromise in ALGS.

Endocytosis, intracellular fate, accumulation, and agglomeration of titanium dioxide (TiO2) nanoparticles in the rainbow trout liver cell line RTL-W1

There is increasing evidence that titanium dioxide (TiO2) nanoparticles (NPs) present in water or diet can be taken up by fish and accumulate in internal organs including the liver. However, their further fate in the organ is unknown. This study provides new insights into the interaction, uptake mechanism, intracellular trafficking, and fate of TiO2 NPs (Aeroxide® P25) in fish liver parenchymal cells (RTL-W1) in vitro using high-resolution transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectrometry (spICP-MS) as complementary analytical techniques. The results demonstrate that following their uptake via caveolae-mediated endocytosis, TiO2 NPs were trafficked through different intracellular compartments including early endosomes, multivesicular bodies, and late endosomes/endo-lysosomes, and eventually concentrated inside multilamellar vesicles. TEM and spICP-MS results provide evidence that uptake was nano-specific. Only NPs/NP agglomerates of a specific size range (~ 30-100 nm) were endocytosed; larger agglomerates were excluded from uptake and remained located in the extracellular space/exposure medium. NP number and mass inside cells increased linearly with time and was associated with an increase in particle diameter suggesting intracellular agglomeration/aggregation. No alterations in the expression of genes regulated by the redox balance-sensitive transcription factor Nrf-2 including superoxide dismutase, glutamyl cysteine ligase, glutathione synthetase, glutathione peroxidase, and glutathione S-transferase were observed. This shows that, despite the high intracellular NP burden (~ 3.9 × 102 ng Ti/mg protein after 24 h) and NP-interaction with mitochondria, cellular redox homeostasis was not significantly affected. This study contributes to a better mechanistic understanding of in vitro particokinetics as well as the potential fate and effects of TiO2 NPs in fish liver cells.

Improving near-peer teaching quality in anatomy by educating teaching assistants: An example from Sweden

Peer-assisted learning has gained momentum in a variety of disciplines, including medical education. In Gothenburg, Sweden, medical students who have finished their compulsory anatomy courses have the option of working as teaching assistants (TAs). Teaching assistants provide small group teaching sessions as a complement to lectures given by faculty. Previously, TAs were left to handle the role as junior teachers by themselves, but since 2011, a continuation course in anatomy has been developed with the aim of providing the TAs better anatomy knowledge and guidance for teaching. The course was designed to comprise 7.5 ECTS credits (equivalent to 5 weeks of full-time studies), and today all TAs are required to take this course before undertaking their own teaching responsibilities. This study aims to compare course evaluations of TA teaching before and after the introduction of the anatomy continuation course, in order to understand how students perceived teaching performed by self-learned versus trained TAs. The results of this study demonstrate that there was a trend towards better teaching performed by trained TAs. The variability in rankings decreased significantly after the introduction of the continuation course. This was mainly due to an improvement among the TAs with the lowest levels of performance. In addition to comparing student rankings, TAs were interviewed regarding their experiences and perceptions within the continuation course. The course was generally positively regarded. The TAs described a sense of cohesion and appreciation since the institute invested in a course dedicated specifically for them. Anat Sci Educ 11: 403-409. © 2018 American Association of Anatomists.

Comparison of the glycosphingolipids of human-induced pluripotent stem cells and human embryonic stem cells

High expectations are held for human-induced pluripotent stem cells (hiPSC) since they are established from autologous tissues thus overcoming the risk of allogeneic immune rejection when used in regenerative medicine. However, little is known regarding the cell-surface carbohydrate antigen profile of hiPSC compared with human embryonic stem cells (hESC). Here, glycosphingolipids were isolated from an adipocyte-derived hiPSC line, and hiPSC and hESC glycosphingolipids were compared by concurrent characterization by binding assays with carbohydrate-recognizing ligands and mass spectrometry. A high similarity between the nonacid glycosphingolipids of hiPSC and hESC was found. The nonacid glycosphingolipids P1 pentaosylceramide, x2 pentaosylceramide and H type 1 heptaosylceramide, not previously described in human pluripotent stem cells (hPSC), were characterized in both hiPSC and hESC. The composition of acid glycosphingolipids differed, with increased levels of GM3 ganglioside, and reduced levels of GD1a/GD1b in hiPSC when compared with hESC. In addition, the hESC glycosphingolipids sulf-globopentaosylceramide and sialyl-globotetraosylceramide were lacking in hiPSC. Neural stem cells differentiating from hiPSC had a reduced expression of sialyl-lactotetra, whereas expression of the GD1a ganglioside was significantly increased. Thus, while sialyl-lactotetra is a marker of undifferentiated hPSC, GD1a is a novel marker of neural differentiation.

Overexpression of protein kinase STK25 in mice exacerbates ectopic lipid accumulation, mitochondrial dysfunction and insulin resistance in skeletal muscle

AIMS/HYPOTHESIS

Understanding the molecular networks controlling ectopic lipid deposition and insulin responsiveness in skeletal muscle is essential for developing new strategies to treat type 2 diabetes. We recently identified serine/threonine protein kinase 25 (STK25) as a critical regulator of liver steatosis, hepatic lipid metabolism and whole body glucose and insulin homeostasis. Here, we assessed the role of STK25 in control of ectopic fat storage and insulin responsiveness in skeletal muscle.

METHODS

Skeletal muscle morphology was studied by histological examination, exercise performance and insulin sensitivity were assessed by treadmill running and euglycaemic-hyperinsulinaemic clamp, respectively, and muscle lipid metabolism was analysed by ex vivo assays in Stk25 transgenic and wild-type mice fed a high-fat diet. Lipid accumulation and mitochondrial function were also studied in rodent myoblasts overexpressing STK25. Global quantitative phosphoproteomics was performed in skeletal muscle of Stk25 transgenic and wild-type mice fed a high-fat diet to identify potential downstream mediators of STK25 action.

RESULTS

We found that overexpression of STK25 in transgenic mice fed a high-fat diet increases intramyocellular lipid accumulation, impairs skeletal muscle mitochondrial function and sarcomeric ultrastructure, and induces perimysial and endomysial fibrosis, thereby reducing endurance exercise capacity and muscle insulin sensitivity. Furthermore, we observed enhanced lipid accumulation and impaired mitochondrial function in rodent myoblasts overexpressing STK25, demonstrating an autonomous action for STK25 within cells. Global phosphoproteomic analysis revealed alterations in the total abundance and phosphorylation status of different target proteins located predominantly to mitochondria and sarcomeric contractile elements in Stk25 transgenic vs wild-type muscle, respectively, providing a possible molecular mechanism for the observed phenotype.

CONCLUSIONS/INTERPRETATION

STK25 emerges as a new regulator of the complex interplay between lipid storage, mitochondrial energetics and insulin action in skeletal muscle, highlighting the potential of STK25 antagonists for type 2 diabetes treatment.

Multimodal Imaging of Chemically Fixed Cells in Preparation for NanoSIMS

In this work, we have employed time-of-flight secondary ion mass spectrometry (ToF-SIMS) to image chemically fixed adrenal cells prepared for transmission electron microscopy (TEM) and subsequent high-spatial-resolution NanoSIMS imaging. The sample fixation methodology preserves cell morphology, allows analysis in the ultrahigh vacuum environment, and reduces topographic artifacts, thus making these samples particularly favorable for ToF-SIMS analysis. ToF-SIMS imaging enables us to determine the chemistry and preservation capabilities of the chemical fixation as well as to locate specific ion species from OsO4. The OsO4 species have been localized in lysosomes of cortical cells, a type of adrenal cell present in the culture. NanoSIMS imaging of the (190)Os(16)O(-) ion species in cortical cells reveals the same localization as a wide range of OsO4 ions shown with ToF-SIMS. Even though we did not use during NanoSIMS imaging the exact OsxOy(-) ion species discovered with ToF-SIMS, ToF-SIMS allowed us to define the specific subcellular features in a high spatial resolution imaging mode. This study demonstrates the possibility for application of ToF-SIMS as a screening tool to optimize high-resolution imaging with NanoSIMS, which could replace TEM for localization in ultrahigh resolution imaging analyses.

STK25 is a critical determinant in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and 10-20% of patients with NAFLD progress to nonalcoholic steatohepatitis (NASH) with a high risk of cirrhosis, liver failure, and hepatocellular carcinoma. Despite its high medical importance, the molecular mechanisms controlling progression from simple liver steatosis to NASH remain elusive. We recently identified serine/threonine protein kinase (STK)25 as a critical regulator of ectopic lipid deposition, systemic glucose, and insulin homeostasis. To elucidate the role of STK25 in the development of NASH, we challenged Stk25-knockout and transgenic mice with a methionine and choline-deficient (MCD) diet. We show that Stk25^-/- mice are protected against MCD-diet-induced NASH, as evidenced by repressed liver steatosis, oxidative damage, inflammation, and fibrosis, whereas Stk25 transgenic mice developed a more severe NASH phenotype, compared with corresponding wild-type littermates. Consistently, NASH features were suppressed in STK25-deficient human hepatocytes cultured in MCD medium, and reciprocally enhanced in STK25-overexpressing cells. We also found a significant positive correlation in human liver biopsies between STK25 expression and NASH development. The study provides evidence for multiple roles of STK25 in NASH pathogenesis and future investigations to address the potential therapeutic relevance of pharmacological STK25 inhibitors in prevention and treatment of NASH are warranted.-Amrutkar, M., Chursa, U., Kern, M., Nuñez-Durán, E., Ståhlman, M., Sütt, S., Borén, J., Johansson, B. R., Marschall, H.-U., Blüher, M., Mahlapuu, M. STK25 is a critical determinant in nonalcoholic steatohepatitis.

A role for PDGF-C/PDGFRα signaling in the formation of the meningeal basement membranes surrounding the cerebral cortex

Platelet-derived growth factor-C (PDGF-C) is one of three known ligands for the tyrosine kinase receptor PDGFRα. Analysis ofPdgfcnull mice has demonstrated roles for PDGF-C in palate closure and the formation of cerebral ventricles, but redundancy with other PDGFRα ligands might obscure additional functions. In search of further developmental roles for PDGF-C, we generated mice that were double mutants forPdgfc(-/-)andPdgfra(GFP/+) These mice display a range of severe phenotypes including spina bifida, lung emphysema, abnormal meninges and neuronal over-migration in the cerebral cortex. We focused our analysis on the central nervous system (CNS), where PDGF-C was identified as a critical factor for the formation of meninges and assembly of the glia limitans basement membrane. We also present expression data onPdgfa,PdgfcandPdgfrain the cerebral cortex and microarray data on cerebral meninges.

Staphylokinase Control of Staphylococcus aureus Biofilm Formation and Detachment Through Host Plasminogen Activation

Staphylococcus aureus biofilms, a leading cause of persistent infections, are highly resistant to immune defenses and antimicrobial therapies. In the present study, we investigated the contribution of fibrin and staphylokinase (Sak) to biofilm formation. In both clinical S. aureus isolates and laboratory strains, high Sak-producing strains formed less biofilm than strains that lacked Sak, suggesting that Sak prevents biofilm formation. In addition, Sak induced detachment of mature biofilms. This effect depended on plasminogen activation by Sak. Host-derived fibrin, the main substrate cleaved by Sak-activated plasminogen, was a major component of biofilm matrix, and dissolution of this fibrin scaffold greatly increased susceptibility of biofilms to antibiotics and neutrophil phagocytosis. Sak also attenuated biofilm-associated catheter infections in mouse models. In conclusion, our results reveal a novel role for Sak-induced plasminogen activation that prevents S. aureus biofilm formation and induces detachment of existing biofilms through proteolytic cleavage of biofilm matrix components.

Foxf2 Is Required for Brain Pericyte Differentiation and Development and Maintenance of the Blood-Brain Barrier

Pericytes are critical for cerebrovascular maturation and development of the blood-brain barrier (BBB), but their role in maintenance of the adult BBB, and how CNS pericytes differ from those of other tissues, is less well understood. We show that the forkhead transcription factor Foxf2 is specifically expressed in pericytes of the brain and that Foxf2(-/-) embryos develop intracranial hemorrhage, perivascular edema, thinning of the vascular basal lamina, an increase of luminal endothelial caveolae, and a leaky BBB. Foxf2(-/-) brain pericytes were more numerous, proliferated faster, and expressed significantly less Pdgfrβ. Tgfβ-Smad2/3 signaling was attenuated, whereas phosphorylation of Smad1/5 and p38 were enhanced. Tgfβ pathway components, including Tgfβ2, Tgfβr2, Alk5, and integrins αVβ8, were reduced. Foxf2 inactivation in adults resulted in BBB breakdown, endothelial thickening, and increased trans-endothelial vesicular transport. On the basis of these results, FOXF2 emerges as an interesting candidate locus for stroke susceptibility in humans.

Bacteria aerosol spread and wound bacteria reduction with different methods for wound debridement in an animal model

Debridement is essential in wound treatment to remove necrotic tissue and wound bacteria but may lead to bacteria spread by aerosolization. This study investigated the wound bacterial reduction and bacterial transmission induced by debridement using curette, plasma-mediated bipolar radiofrequency ablation (Coblation®) or hydrodebridement (Versajet®). Full thickness dermal wounds in porcine joint specimens inoculated with S. aureus were debrided with curette, Coblation, Versajet, or were left untreated. During and after debridement, aerosolized bacteria were measured and to assess wound bacterial load, quantitative swab samples were taken from each wound. Only Coblation was able to reduce the bacterial load of the wound significantly. Versajet debridement resulted in a significant bacterial aerosolization, but this was not the case with Coblation and curette debridement. This study shows that Coblation is a promising wound debridement method, which effectively reduces the wound bed bacterial load without the risk of bacterial aerosolization.

Notch3 is necessary for blood vessel integrity in the central nervous system

OBJECTIVE

Vascular smooth muscle cells (VSMC) are important for contraction, blood flow distribution, and regulation of blood vessel diameter, but to what extent they contribute to the integrity of blood vessels and blood-brain barrier function is less well understood. In this report, we explored the impact of the loss of VSMC in the Notch3(-/-) mouse on blood vessel integrity in the central nervous system.

APPROACH AND RESULTS

Notch3(-/-) mice showed focal disruptions of the blood-brain barrier demonstrated by extravasation of tracers accompanied by fibrin deposition in the retinal vasculature. This blood-brain barrier leakage was accompanied by a regionalized and patchy loss of VSMC, with VSMC gaps predominantly in arterial resistance vessels of larger caliber. The loss of VSMC appeared to be caused by progressive degeneration of VSMC resulting in a gradual loss of VSMC marker expression and a progressive acquisition of an aberrant VSMC phenotype closer to the gaps, followed by enhanced apoptosis and cellular disintegration in the gaps. Arterial VSMC were the only mural cell type that was morphologically affected, despite Notch3 also being expressed in pericytes. Transcriptome analysis of isolated brain microvessels revealed gene expression changes in Notch3(-/-) mice consistent with loss of arterial VSMC and presumably secondary transcriptional changes were observed in endothelial genes, which may explain the compromised vascular integrity.

CONCLUSIONS

We demonstrate that Notch3 is important for survival of VSMC, and reveal a critical role for Notch3 and VSMC in blood vessel integrity and blood-brain barrier function in the mammalian vasculature.

An alternative approach to decellularize whole porcine heart

Scaffold characteristics are decisive for repopulating the acellular tissue with cells. A method to produce such a scaffold from intact organ requires a customized decellularization protocol. Here, we have decellularized whole, intact porcine hearts by serial perfusion and agitation of hypotonic solution, an ionic detergent (4% sodium deoxycholate), and a nonionic detergent (1% Triton X-100). The resultant matrix was characterized for its degree of decellularization, morphological and functional integrity. The protocol used resulted in extensive decellularization of the cardiac tissue, but the cytoskeletal elements (contractile apparatus) of cardiomyocytes remained largely unaffected by the procedure although their membranous organelles were completely absent. Further, several residual angiogenic growth factors were found to be present in the decellularized tissue.

Ultrastructural evaluation of shrinkage artefacts induced by fixatives and embedding resins on osteocyte processes and pericellular space dimensions

The integrity of the interface between the osteocyte (Ot) process and the canalicular wall was investigated in terms of change in the lateral dimensions of the Ot process in relation to the canalicular width, i.e., widening of the pericellular space. This has been interpreted as shrinkage of the Ot process relative to the canalicular wall during sample preparation stages of fixation, dehydration, and resin embedding. Sprague-Dawley rat tibial cross-sections were prepared for transmission electron microscopy (TEM). Four different fixative preparations: paraformaldehyde (PF), modified Karnovsky's (MK), glutaraldehyde (GRR) with ruthenium red (GRR), and zinc formalin (ZF); and two different embedding resins: LR Gold (LRG) and Epon812 (Epon) were evaluated. It was found that for LRG embedding, formalin-only fixatives (PF and ZF) induced lower shrinkage than GRR-containing fixatives (MK and GRR). In contrast, for Epon embedding, MK showed the highest shrinkage, while no differences were found between the remaining fixatives (PF, ZF, and GRR). All formalin-containing fixatives (MK, PF, and ZF) induced similar shrinkage in both embedding media. The most dramatic difference was for GRR fixation, which in combination with LRG embedding showed ∼ 62% more shrinkage than with Epon embedding, suggesting that the combination of GRR fixation and LRG embedding synergistically amplifies Ot shrinkage. These differences likely suggest a role of the resin in secondarily influencing the tissue structure following fixation. Further, the work confirms LRG as a poor embedding medium for bone specimens, as it causes large variations in shrinkage depending on fixation.

Sialyl-lactotetra, a novel cell surface marker of undifferentiated human pluripotent stem cells

Cell surface glycoconjugates are used as markers for undifferentiated pluripotent stem cells. Here, antibody binding and mass spectrometry characterization of acid glycosphingolipids isolated from a large number (1 × 10⁹ cells) of human embryonic stem cell (hESC) lines allowed identification of several novel acid glycosphingolipids, like the gangliosides sialyl-lactotetraosylceramide and sialyl-globotetraosylceramide, and the sulfated glycosphingolipids sulfatide, sulf-lactosylceramide, and sulf-globopentaosylceramide. A high cell surface expression of sialyl-lactotetra on hESC and human induced pluripotent stem cells (hiPSC) was demonstrated by flow cytometry, immunohistochemistry, and electron microscopy, whereas sulfated glycosphingolipids were only found in intracellular compartments. Immunohistochemistry showed distinct cell surface anti-sialyl-lactotetra staining on all seven hESC lines and three hiPSC lines analyzed, whereas no staining of hESC-derived hepatocyte-like or cardiomyocyte-like cells was obtained. Upon differentiation of hiPSC into hepatocyte-like cells, the sialyl-lactotetra epitope was rapidly down-regulated and not detectable after 14 days. These findings identify sialyl-lactotetra as a promising marker of undifferentiated human pluripotent stem cells.

Subcellular localization of an ATPase in anammox bacteria using proteomics and immunogold electron microscopy

Anaerobic ammonium oxidation (anammox) has received significant attention during optimization of waste-water treatment and constitutes an important pathway for the removal of bioavailable nitrogen from natural environments. Studies of key catabolic enzymes indicate that the anammox reaction takes place inside the anammoxosome, an organelle-like membranous compartment of anammox bacteria. The anammoxosome has also been suggested as a site for ATP synthesis. A lipid-based protein immobilization technique, previously used to identify proteins essential for the anammox reaction, was in this study used to select linear epitopes for antibodies specifically targeted against an identified ATPase. The approach of using proteomics and bioinformatics as tools for selecting antibody targets for immunolocalization provides an important alternative to traditional methods for selection of specific antibodies. Immunogold electron microscopy and statistical evaluations indicated that the antibodies against the ATPase were exclusively found associated with the anammoxosome membrane. This provides strong evidence for ATP synthesis by an intracellular proton motive force in anammox bacteria. Within prokaryotes, an ATP synthase associated with an intracellular compartment is a feature unique for anammox bacteria.

Diverse arachnoid cyst morphology indicates different pathophysiological origins

BACKGROUND

There are few, limited, and to some extent contradictory, reports on the cellular and subcellular morphology of arachnoid cysts. In the literature cyst membranes are described as similar to, or as vastly different from, normal arachnoid membranes.

METHODS

This paper reports electron microscopic analyses of symptomatic cysts from 24 patients (12 males and 12 females; age 10-79), that underwent fenestration surgery. Fourteen cysts were located in the middle cranial fossa (temporal), one in the interpeduncular cistern, five in the posterior fossa, and four were overlying the frontal cortex.

RESULTS

Microscopic findings confirmed the diverse nature of this clinical condition. Twelve cyst walls resembled normal arachnoid, four had a conspicuous core of dense fibrous tissue with a simple epithelial lining, and the remaining aberrant cysts exhibited non-arachnoid luminal epithelia with plentiful microvilli and/or cilia, and also nervous tissue components in the wall. The possible identity and origin of various cyst types are discussed. We hypothesize that cysts are formed mostly at an early stage of embryonic development, as a teratological event.

CONCLUSIONS

Cysts with various epithelial linings and extracellular components most likely have different barrier properties and fluid turnover characteristics. Further studies are needed to elucidate relations between cyst morphology, fluid composition, pathogenesis, and clinical behaviour including growth rate and relapse tendency.

Deficiency for endoglin in tumor vasculature weakens the endothelial barrier to metastatic dissemination

Therapy-induced resistance remains a significant hurdle to achieve long-lasting responses and cures in cancer patients. We investigated the long-term consequences of genetically impaired angiogenesis by engineering multiple tumor models deprived of endoglin, a co-receptor for TGF-β in endothelial cells actively engaged in angiogenesis. Tumors from endoglin-deficient mice adapted to the weakened angiogenic response, and refractoriness to diminished endoglin signaling was accompanied by increased metastatic capability. Mechanistic studies in multiple mouse models of cancer revealed that deficiency for endoglin resulted in a tumor vasculature that displayed hallmarks of endothelial-to-mesenchymal transition, a process of previously unknown significance in cancer biology, but shown by us to be associated with a reduced capacity of the vasculature to avert tumor cell intra- and extravasation. Nevertheless, tumors deprived of endoglin exhibited a delayed onset of resistance to anti-VEGF (vascular endothelial growth factor) agents, illustrating the therapeutic utility of combinatorial targeting of multiple angiogenic pathways for the treatment of cancer.

Zfp148 deficiency causes lung maturation defects and lethality in newborn mice that are rescued by deletion of p53 or antioxidant treatment

The transcription factor Zfp148 (Zbp-89, BFCOL, BERF1, htβ) interacts physically with the tumor suppressor p53 and is implicated in cell cycle control, but the physiological role of Zfp148 remains unknown. Here we show that Zfp148 deficiency leads to respiratory distress and lethality in newborn mice. Zfp148 deficiency prevented structural maturation of the prenatal lung without affecting type II cell differentiation or surfactant production. BrdU analyses revealed that Zfp148 deficiency caused proliferation arrest of pulmonary cells at E18.5–19.5. Similarly, Zfp148-deficient fibroblasts exhibited proliferative arrest that was dependent on p53, raising the possibility that cell stress is part of the underlying mechanism. Indeed, Zfp148 deficiency lowered the threshold for activation of p53 under oxidative conditions. Moreover, both in vivo and cellular phenotypes were rescued on Trp53^+/− or Trp53^−/− backgrounds and by antioxidant treatment. Thus, Zfp148 prevents respiratory distress and lethality in newborn mice by attenuating oxidative stress–dependent p53-activity during the saccular stage of lung development. Our results establish Zfp148 as a novel player in mammalian lung maturation and demonstrate that Zfp148 is critical for cell cycle progression in vivo.

Cord-forming mycobacteria induce DNA meshwork formation by human peripheral blood mononuclear cells

Mononuclear phagocytes, that is, monocytes and macrophages, are central in the defense against mycobacteria. Mycobacterium abscessus is an opportunistic mycobacterial species able to cause chronic pulmonary infections in patients with cystic fibrosis but also soft tissue infections in immunocompetent individuals. Pathogenic isolates of M. abscessus with rough colony morphology form cord-like aggregates. In this study, we investigated the in vitro response of human peripheral blood mononuclear cells (PBMCs) from healthy blood donors to cord-forming M. abscessus strains from cystic fibrosis patients with clinical lung infection. Microscopic examination revealed that the PBMCs produced a coarse fibrous meshwork containing DNA and histones, which surrounded the mycobacterial cords. Thus, the bacterial cord formations were entrapped by monocytes and lymphocytes aggregated onto the DNA-rich meshwork fibers. Mycobacterium abscessus strains with smooth colony morphology, which do not form cords and are readily phagocytosed, did not induce any meshwork formation in PBMCs. The chromatin meshwork may represent a defense mechanism against nondigestible invaders.

Antibodies to kidney endothelial cells contribute to a "leaky" glomerular barrier in patients with chronic kidney diseases

Anti-endothelial cell antibodies (AECA) have been reported to cause endothelial dysfunction, but their clinical importance for tissue-specific endothelial cells is not clear. We hypothesized that AECA reactive with human kidney endothelial cells (HKEC) may cause renal endothelial dysfunction in patients with chronic kidney diseases. We report that a higher fraction (56%) of end-stage renal disease (ESRD) patients than healthy controls (5%) have AECA reactive against kidney endothelial cells (P <0.001). The presence of antibodies was associated with female gender (P < 0.001), systolic hypertension (P < 0.01), and elevated TNF-α (P < 0.05). These antibodies markedly decrease expression of both adherens and tight junction proteins VE-cadherin, claudin-1, and zonula occludens-1 and provoked a rapid increase in cytosolic free Ca(2+) and rearrangement of actin filaments in HKEC compared with controls. This was followed by an enhancement in protein flux and phosphorylation of VE-cadherin, events associated with augmented endothelial cell permeability. Additionally, kidney biopsies from ESRD patients with AECA but not controls demonstrated a marked decrease in adherens and tight junctions in glomerular endothelium, confirming our in vitro data. In summary, our data demonstrate a causal link between AECA and their capacity to induce alterations in glomerular vascular permeability.

Electron microscopy analysis of neurites extending from dorsal root ganglia in vitro following exposure to intervertebral disc cells

Nucleus pulposus cells from the intervertebral disc have been shown to have inhibiting effects on neurite outgrowth in vitro. The nucleus pulposus consists of at least 2 cell populations, notochordal cells and chondrocyte-like cells. The aim of this study was to analyze the morphology of the neurites, from rat dorsal root ganglia (DRG) in a culture system, after exposure of these 2 cell populations. DRG from perinatal rats was harvested and placed in culture dishes for 24 h. Nucleus pulposus cells from donor rats were separated into 2 populations and applied to the DRG and neurite culture for a further 24 h and compared to control cultures exposed to culture medium without cells. The DRG and neurites were thereafter prepared for scanning or transmission electron microscopy (SEM/TEM). Descriptive SEM and TEM analyses and calculations of the neurite diameter were performed. The visual appearance after SEM and TEM preparation was similar in the three different culture conditions. However, there was a statistically significant reduction of the neurite diameter for the cultures exposed to notochordal cells compared to the cultures exposed to medium and chondrocyte-like cells (TEM preparation). Prominent and frequent pathologic abnormalities in peripheral nerve diseases have been observed with changes in axonal caliber. This study may suggest that a preserved small amount of notochordal cells, as seen in human adults, may play a role in clinical situations where nerve tissue is exposed to disc material, i.e. in disc herniation or degeneration.

Isolation of brain mitochondria from neonatal mice

Mitochondria are key contributors to many forms of cell death including those resulting from neonatal hypoxic-ischemic brain injury. Mice have become increasingly popular in studies of brain injury, but there are few reports evaluating mitochondrial isolation procedures for the neonatal mouse brain. Using evaluation of respiratory activity, marker enzymes, western blotting and electron microscopy, we have compared a previously published procedure for isolating mitochondria from neonatal mouse brain (method A) with procedures adapted from those for adult rats (method B) and neonatal rats (method C). All three procedures use Percoll density gradient centrifugation as a key step in the isolation but differ in many aspects of the fractionation procedure and the solutions used during fractionation. Methods A and B both produced highly enriched fractions of well-coupled mitochondria with high rates of respiratory activity. The fraction from method C exhibited less preservation of respiratory properties and was more contaminated with other subcellular components. Method A offers the advantage of being more rapid and producing larger mitochondrial yields making it useful for routine applications. However, method B produced mitochondria that were less contaminated with synaptosomes and associated cytosolic components that suits studies that have a requirement for higher mitochondrial purification.

Tumor cure probability during alpha-RIT of ovarian cancer with different radiation sensitivity

PURPOSE

To calculate the tumor cure probability (TCP) and metastatic cure probability (MCP) during alpha-radioimmunotherapy (alpha-RIT) of small ovarian cancer tumors with cells of different radiation sensitivity.

MATERIALS AND METHODS

An in-house-developed biokinetic model and a Monte-Carlo program were used to calculate the cumulative activity on tumor cell surfaces and the specific energy to tumor cell nuclei, respectively. An in-house-developed computational model was used to calculate the TCP and MCP as a function of assumed radiation sensitivities, expressed as D(37), of the tumor cells. The calculations were performed using various assumptions regarding the activity distribution in measured tumors and used the alpha-particle energies emitted from astatine-211 ((211)At). Regarding the calculations of the cumulative activity on each cell surface, the number of antigenic sites expressed by NIH:OVCAR-3 cells for the mAb MX35 F(ab')2 was used. To illustrate the tumor growth at the peritoneum in nude mice, scanning electron microscopy images were used.

RESULTS

In the case of a maximum diffusion depth of 30 mum for the activity in the tumors, the TCP was high for D(37) values not exceeding approximately 4.3, approximately 2.9, approximately 1.8, and approximately 0.8 Gy for 200, 100, 50, and 25 kBq (211)At-MX35 F(ab')2 four weeks after cell inoculation, respectively. In order to achieve complete remission of the metastatic disease in mice (i.e. MCP=1), the D(37) value should not exceed approximately 2.2, approximately 1.3, approximately 0.6, and approximately 0.3 Gy when injecting 200, 100, 50, or 25 kBq, respectively, assuming a maximum diffusion depth of 30 mum for the activity in the tumors.

CONCLUSION

The radiation sensitivity, expressed as D(37), of tumor cells subjected to alpha-RIT could be decisive for therapeutic outcome, expressed as TCP or MCP, when treating small tumors of ovarian cancer.

Intraperitoneal Alpha-Radioimmunotherapy of Advanced Ovarian Cancer in Nude Mice Using Different High Specific Activities

Background

The aim of this study was to investigate the therapeutic efficacy of advanced ovarian cancer in mice, using α-radioimmunotherapy with different high specific activities. The study was performed using the monoclonal antibody (mAb) MX35 F(ab′)2 labeled with the α-particle emitter ²¹¹At.

Methods

Animals were intraperitoneally inoculated with ≥1 × 10⁷ cells of the ovarian cancer cell line NIH:OVCAR-3. Four weeks later 9 groups of animals were given 25, 50, or 400 kBq ²¹¹At-MX35 F(ab′)2 with specific activities equal to 1/80, 1/500, or 1/1200 (²¹¹At atom/number of mAbs) for every activity level respectively (n = 10 in each group). As controls, animals were given PBS or unlabeled MX35 F(ab′)2 in PBS (n = 10 in each group). Eight weeks after treatment the animals were sacrificed and the presence of macroscopic tumors was determined by meticulous ocular examination of the abdominal cavity. Cumulated activity and absorbed dose calculations on tumor cells and tumors were performed using in house developed program. Specimens for scanning electron-microscopy analysis were collected from the peritoneum at the time of dissection.

Results

Summing over the different activity levels (25, 50, and 400 kBq ²¹¹At-MX35 F(ab′)2) the number of animals with macroscopic tumors was 13, 17, and 22 (n = 30 for each group) for the specific activities equal to 1/80, 1/500, or 1/1200, respectively. Logistic-regression analysis showed a significant trend that higher specific activity means less probability for macroscopic tumors (P = 0.02).

Conclusions

Increasing the specific activity indicates a way to enhance the therapeutic outcome of advanced ovarian cancer, regarding macroscopic tumors. Further studies of the role of the specific activity are therefore justified.

Lipid droplets interact with mitochondria using SNAP23

Triglyceride-containing lipid droplets (LD) are dynamic organelles stored on demand in all cells. These droplets grow through a fusion process mediated by SNARE proteins, including SNAP23. The droplets have also been shown to be highly motile and interact with other cell organelles, including peroxisomes and the endoplasmic reticulum. We have used electron and confocal microscopy to demonstrate that LD form complexes with mitochondria in NIH 3T3 fibroblasts. Using an in vitro system of purified LD and mitochondria, we also show the formation of the LD-mitochondria complex, in which cytosolic factors are involved. Moreover, the presence of LD markers in mitochondria isolated by subcellular fractionations is demonstrated. Finally, ablation of SNAP23 using siRNA reduced complex formation and beta oxidation, which suggests that the LD-mitochondria complex is functional in the cell.

Human NK cell lines migrate differentially in vitro related to matrix interaction and MMP expression

Matrix metalloproteinases (MMPs) are thought to be of importance for the migratory ability of natural killer (NK) cells. Their expression and production may influence the amount of tumour-infiltrating NK cells and thereby any therapeutic capability. In this study, we sought to investigate the importance of MMPs for human NK cells' ability to degrade and migrate through the extracellular matrix (ECM). The two human NK cell lines, NK-92 and YT, migratory ability, MMP expression and production as well as their morphological appearance when cultured in the ECM equivalent Matrigel were analysed and compared. The quantitatively more migratory NK-92 cells were found to express invadopodia/podosomes at a significantly higher degree when cultured in Matrigel and gave rise to a general disintegration of the Matrigel. The NK-92 cells had a higher mRNA expression of MMP-2, -9, -13, MT1-, MT3- and MT6-MMP and a significantly higher production of MMP-9 compared to YT cells. These differences could explain the substantial functional difference observed between the two cell lines with respect to migratory capacity. In addition, the number of Matrigel invading NK-92 cells decreased significantly in the presence of the MMP inhibitor GM6001, demonstrating that MMPs have a critical function in their migration.

Ultrastructure of the microvessels in skeletal muscle in a case of systemic capillary leak syndrome

The microvessels of skeletal muscle were examined electron microscopically in a case of systemic capillary leak syndrome (SCLS). One biopsy was taken in a free interval of the disease and one about 6 hours after the onset of an attack with hypovolemia. The microvascular endothelium exhibited a large number of multivesicular bodies, especially in the specimen obtained during an attack. Possibly this indicates a high heterophagic activity of the endothelium. A blebbing of the luminal surface of arteriolar endothelium was observed in the attack specimen. Since a complement activation seemed to occur during attacks, the blebbing is tentatively interpreted as a sign of a complement-mediated injury to the endothelium, leading to a breakdown of the endothelial barrier. This mechanism might explain the dramatic increase of microvascular permeability to plasma proteins during an attack of SCLS. The findings did not indicate that the increase might depend on some disturbance of the transendothelial vesicular transport function, nor could any openings of endothelial junctions, as in inflammation, be demonstrated. Regionally the periendothelial basal lamina appeared thickened, a finding which seems common in angiopathies of different kinds.

Systemic capillary leak syndrome with monoclonal IgG and complement alterations. A case report on an episodic syndrome

A case of the rare systemic capillary leak syndrome (SCLS) is described. The patient suffered 9 attacks with muscle pain, weakness and profuse sweating. He showed increased Hct values up to 79 percent and a decreasing plasma volume to about 50 percent of normal. During the attacks the patient was in a state of shock and BP was unmeasurable. Studies with 131I-labelled albumin during attack showed an increased transcapillary escape rate to about 20 percent/hour, compared to 6 percent when he was without symptoms. A monoclonal IgG with a constant concentration of about 5g/l was found. Studies of the complement system during attack showed low C4 values, disproportions among the C1 subcomponents and C1r-C1s-C1IA complexes, suggesting a complement activation via the classic pathway. Hereditary angio-edema was excluded by normal C1IA values. The complement activation might be part of the pathogenesis of the increased macromolecular permeability in this syndrome. A short review of cases described earlier is given.

Developmental shift of cyclophilin D contribution to hypoxic-ischemic brain injury

Cyclophilin D (CypD), a regulator of the mitochondrial membrane permeability transition pore (PTP), enhances Ca(2+)-induced mitochondrial permeabilization and cell death in the brain. However, the role of CypD in hypoxic-ischemic (HI) brain injury at different developmental ages is unknown. At postnatal day (P) 9 or P60, littermates of CypD-deficient [knock-out (KO)], wild-type (WT), and heterozygous mice were subjected to HI, and brain injury was evaluated 7 d after HI. CypD deficiency resulted in a significant reduction of HI brain injury at P60 but worsened injury at P9. After HI, caspase-dependent and -independent cell death pathways were more induced in P9 CypD KO mice than in WT controls, and apoptotic activation was minimal at P60. The PTP had a considerably higher induction threshold and lower sensitivity to cyclosporin A in neonatal versus adult mice. On the contrary, Bax inhibition markedly reduced caspase activation and brain injury in immature mice but was ineffective in the adult brain. Our findings suggest that CypD/PTP is critical for the development of brain injury in the adult, whereas Bax-dependent mechanisms prevail in the immature brain. The role of CypD in HI shifts from a predominantly prosurvival protein in the immature to a cell death mediator in the adult brain.

Developmental origin of smooth muscle cells in the descending aorta in mice

Aortic smooth muscle cells (SMCs) have been proposed to derive from lateral plate mesoderm. It has further been suggested that induction of SMC differentiation is confined to the ventral side of the aorta, and that SMCs later migrate to the dorsal side. In this study, we investigate the origin of SMCs in the descending aorta using recombination-based lineage tracing in mice. Hoxb6-cre transgenic mice were crossed with Rosa 26 reporter mice to track cells of lateral plate mesoderm origin. The contribution of lateral plate mesoderm to SMCs in the descending aorta was determined at different stages of development. SMC differentiation was induced in lateral plate mesoderm-derived cells on the ventral side of the aorta at embryonic day (E) 9.0-9.5, as indicated by expression of the SMC-specific reporter gene SM22alpha-lacZ. There was, however, no migration of SMCs from the ventral to the dorsal side of the vessel. Moreover, the lateral plate mesoderm-derived cells in the ventral wall of the aorta were replaced by somite-derived cells at E10.5, as indicated by reporter gene expression in Meox1-cre/Rosa 26 double transgenic mice. Examination of reporter gene expression in adult aortas from Hoxb6-cre/Rosa 26 and Meox1-cre/Rosa 26 double transgenic mice suggested that all SMCs in the adult descending aorta derive from the somites, whereas no contribution was recorded from lateral plate mesoderm.

Differential locomotion of long- and short-term IL-2-activated murine natural killer cells in a model matrix environment

Tumour infiltration by activated natural killer (A-NK) cells is a pre-requisite for tumour eradication by adoptive NK cell transfer. Extravasated A-NK cells do not always succeed in reaching the crucial target cell conjugation. Therefore, we wished to study A-NK cell locomotion and interactions with melanoma cells in a matrix environment (Matrigel) by electron, confocal and fluorescence microscopy. Two distinct patterns of A-NK cell-mediated matrix disintegration were revealed during incubation of tumour cells and A-NK cells in Matrigel: (1) A-NK cells pre-cultured for 5 days altered the homogeneous texture of the Matrigel, an initial microporous appearance became a loose filamentous meshwork by 24 h. Matrix degrading protease inhibitors could not fully prevent this, but could delay the process; and (2) A-NK cells pre-cultured for 6 days or more, instead formed large excavations in the Matrigel leaving the remaining matrix less affected compared to the effects by the younger A-NK cells. By histochemical staining with Cupromeronic Blue, the excavations were shown to contain proteoglycan material. Protease inhibitors had no discernable effect on the development of the excavations. The conspicuous capacity of A-NK cells to disintegrate extracellular matrix and the formation of large excavations seems only partially to depend on matrix-degrading proteases. Formation of extracellular proteoglycan material is suggested to facilitate A-NK cell locomotion within a matrix environment.

Administered activity and metastatic cure probability during radioimmunotherapy of ovarian cancer in nude mice with 211At-MX35 F(ab')2

PURPOSE

To elucidate the therapeutic efficacy of alpha-radioimmunotherapy of ovarian cancer in mice. This study: (i) estimated the minimum required activity (MRA), giving a reasonable high therapeutic efficacy; and (ii) calculated the specific energy to tumor cell nuclei and the metastatic cure probability (MCP) using various assumptions regarding monoclonal-antibody (mAb) distribution in measured tumors. The study was performed using the alpha-particle emitter Astatine-211 (211At) labeled to the mAb MX35 F(ab')2.

METHODS AND MATERIALS

Animals were inoculated intraperitoneally with approximately 1 x 10(7) cells of the cell line NIH:OVCAR-3. Four weeks later animals were treated with 25, 50, 100, or 200 kBq 211At-MX35 F(ab')2 (n = 74). Another group of animals was treated with a nonspecific mAb: 100 kBq 211At-Rituximab F(ab')2 (n = 18). Eight weeks after treatment the animals were sacrificed and presence of macro- and microscopic tumors and ascites was determined. An MCP model was developed and compared with the experimentally determined tumor-free fraction (TFF).

RESULTS

When treatment was given 4 weeks after cell inoculation, the TFFs were 25%, 22%, 50%, and 61% after treatment with 25, 50, 100, or 200 kBq (211)At-MX35 F(ab')2, respectively, the specific energy to irradiated cell nuclei varying between approximately 2 and approximately 400 Gy.

CONCLUSION

As a significant increase in the therapeutic efficacy was observed between the activity levels of 50 and 100 kBq (TFF increase from 22% to 50%), the conclusion was that the MRA is approximately 100 kBq (211)At-MX35 F(ab')2. MCP was most consistent with the TFF when assuming a diffusion depth of 30 mum of the mAbs in the tumors.

Foxe3 is required for morphogenesis and differentiation of the anterior segment of the eye and is sensitive to Pax6 gene dosage

The dysgenetic lens (dyl) mouse mutant has mutations in Foxe3, which inactivate DNA binding by the encoded forkhead transcription factor. Here we confirm, by targeted inactivation, that Foxe3 mutations are responsible for the dyl phenotype, which include loss of lens epithelium; a small, cataractic lens; and failure of the lens to detach from the surface ectoderm. In contrast to a recent report of targeted Foxe3, we found no phenotypic difference between dyl and Foxe3(-/-) mutants when congenic strains were compared, and thus nothing that argues against Foxe3(dyl) being a null allele. In addition to the lens, most tissues of the anterior segment-iris, cornea, ciliary body and trabecular meshwork-are malformed or show differentiation defects. Many of these abnormalities, such as irido-corneal and irido-lenticular adherences, are present in a less severe form in mice heterozygous for the Foxe3 mutation, in spite of these having an intact lens epithelium. Early Foxe3 expression is highly sensitive to a halved Pax6 gene dosage and there is a striking phenotypic similarity between Pax6 and Foxe3 mutants. We therefore propose that many of the ocular malformations associated with Pax6 haploinsufficiency are consequences of a reduced expression of Foxe3.

Alpha-radioimmunotherapy of intraperitoneally growing OVCAR-3 tumors of variable dimensions: Outcome related to measured tumor size and mean absorbed dose

The purpose of this work was to (a) investigate the efficacy of radioimmunotherapy using 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2 (nonspecific antibody) against differently advanced ovarian cancer in mice; (b) image the tumor growth on the peritoneum; and (c) calculate the specific energy and mean absorbed dose to tumors and critical organs.

METHODS

Two experiments with 5-wk-old nude mice (n = 100 + 93), intraperitoneally inoculated with approximately 1 x 10(7) NIH:OVCAR-3 cells, were done. At either 1, 3, 4, 5, or 7 wk after inoculation animals were intraperitoneally treated with approximately 400 kBq 211At-MX35 F(ab')2 (n = 50 + 45), approximately 400 kBq 211At-Rituximab F(ab')2 (n = 25 + 24), or unlabeled Rituximab F(ab')2 (n = 25 + 24). At the time of treatment 29 animals were sacrificed and biopsies were taken for determination of tumor sizes using scanning electron microscopy (SEM). Eight weeks after each treatment the animals were sacrificed and the presence of macro- and microscopic tumors and ascites was determined. The specific energy and mean absorbed dose to tumors were calculated. The activity concentration was measured in critical organs and abdominal fluid.

RESULTS

When given treatment 1, 3, 4, 5, or 7 wk after cell inoculation the tumor-free fraction (TFF) was 95%, 68%, 58%, 47%, 26%, and 100%, 80%, 20%, 20%, and 0% when treated with 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2, respectively. The SEM images revealed maximum tumor radius of approximately 30 mum 1 wk after cell inoculation, increasing to approximately 340 mum at 7 wk. Specific energy to cell nuclei varied between 0 and approximately 540 Gy, depending on assumptions regarding activity distribution and tumor size. The mean absorbed dose to thyroid, kidneys, and bone marrow was approximately 35, approximately 4, and approximately 0.3 Gy, respectively.

CONCLUSION

Treatment with 211At-MX35 F(ab')2 or 211At-Rituximab F(ab')2 resulted in a TFF of 95%-100% when the tumor radius was < or =30 microm. The TFF was decreased (TFF < or = 20%) for 211At-Rituximab F(ab')2 when the tumor radius exceeded the range of the alpha-particles. The specific antibody gave for these tumor sizes a significantly better TFF, explained by a high mean absorbed dose (>22 Gy) from the activity bound to the tumor surface and probably some contribution from penetrating activity.

Tubular mitochondrial alterations in neonatal rats subjected to RAS inhibition

Pharmacological interruption of the angiotensin II (ANG II) type 1 receptor signaling during nephrogenesis in rats perturbs renal tubular development. This study aimed to further investigate tubular developmental defects in neonatal rats subjected to ANG II inhibition with enalapril. We evaluated tubular ultrastructural changes using electron microscopy and estimated spectrophotometrically activity or concentrations of succinate dehydrogenase (SDH), cytochromes a and c, which are components of mitochondrial respiratory chain, on postnatal days 2 and 9 (PD2 and PD9). Renal expression of sodium-potassium adenosinetriphosphatase (Na+-K+-ATPase) and two reflectors of mitochondrial biogenesis [mitochondrial transcription factor A (TFAM) and translocase of outer mitochondrial membrane 20 (TOM20)] also were studied using Western immunoblotting and immunohistochemistry. Enalapril disrupted inner mitochondrial membranes of developing cortical and medullary tubular cells on PD2 and PD9. These findings were paralleled by impaired mitochondrial respiratory function, as revealed from the changes in components of the mitochondrial respiratory chain, such as decreased cytochrome c level in the cortex and medulla on PD2 and PD9, decreased cytochrome a level in the cortex and medulla on PD2, and diminished cortical SDH activity on PD2 and PD9. Moreover, tubular expression of the most active energy-consuming pump Na+-K+-ATPase was decreased by enalapril treatment. Renal expression of TFAM and TOM20 was not altered by neonatal enalapril treatment. Because nephrogenesis is a highly energy-demanding biological process, with the energy being utilized for renal growth and transport activities, the structural-functional alterations of the mitochondria induced by neonatal enalapril treatment may provide the propensity for the tubular developmental defect.

Production of Extracellular Matrix Components in Tissue-Engineered Blood Vessels

Morphology and compliance of tissue-engineered blood vessels (TEBV) are dependent on the culture period and production of extracellular matrix (ECM) components in order to increase the strength of the developing tissue. The aim of the present study was to evaluate the potential of TEBVs to produce an ECM similar to native arteries and veins. Human smooth muscle cells (SMC) were seeded onto the poly(glycolic acid) (PGA) scaffold and placed in bioreactors filled with DMEM supplemented with growth factors. After 6 weeks, the vessels were harvested from the bioreactors and seeded with human endothelial cells at the lumen for another 3 days. Then, the TEBVs were harvested for RNA and protein isolation for further RT-PCR and Western blot. TEBVs had a similar macroscopic appearance to that of native vessels with no visible evidence of the original PGA. Histological and immunohistochemical analyses indicated the presence of high cell density and development of a highly organized structure of ECM. After 6 weeks of culture, there were significantly lower gene expression of SMC-specific markers, such as alpha-actin, caldesmon, and vimentin, and proteoglycans, such as biglycan, decorin, and versican, and other ECM components, such as collagen I and elastin, in TEBVs, with and without pulsatile conditions, compared to that of native arteries. Gene expression of fibronectin was significantly lower in TEBVs grown during pulsatile conditions compared to that of native arteries. No difference was observed in TEBVs grown during non-pulsatile conditions. The presence of alpha-actin, collagen I, decorin, and fibronectin at protein level was demonstrated in TEBVs with and without pulsatile conditions after 6 weeks and in native veins and arteries as well. How this deviation translates into mechanical properties remains to be explored.

Foxf1andFoxf2control murine gut development by limiting mesenchymal Wnt signaling and promoting extracellular matrix production

Development of the vertebrate gut is controlled by paracrine crosstalk between the endodermal epithelium and the associated splanchnic mesoderm. In the adult, the same types of signals control epithelial proliferation and survival, which account for the importance of the stroma in colon carcinoma progression. Here, we show that targeting murine Foxf1 and Foxf2, encoding forkhead transcription factors, has pleiotropic effects on intestinal paracrine signaling. Inactivation of both Foxf2alleles, or one allele each of Foxf1 and Foxf2, cause a range of defects, including megacolon, colorectal muscle hypoplasia and agangliosis. Foxf expression in the splanchnic mesoderm is activated by Indian and sonic hedgehog secreted by the epithelium. In Foxf mutants, mesenchymal expression of Bmp4 is reduced, whereas Wnt5a expression is increased. Activation of the canonical Wnt pathway – with nuclear localization of β-catenin in epithelial cells – is associated with over-proliferation and resistance to apoptosis. Extracellular matrix,particularly collagens, is severely reduced in Foxf mutant intestine, which causes epithelial depolarization and tissue disintegration. Thus, Foxf proteins are mesenchymal factors that control epithelial proliferation and survival, and link hedgehog to Bmp and Wnt signaling.

Mechanical properties of bacterial cellulose and interactions with smooth muscle cells

Tissue engineered blood vessels (TEBV) represent an attractive approach for overcoming reconstructive problems associated with vascular diseases by providing small calibre vascular grafts. The aim of this study has been to evaluate a novel biomaterial, bacterial cellulose (BC), as a potential scaffold for TEBV. The morphology of the BC pellicle grown in static culture was investigated with SEM. Mechanical properties of BC were measured in Krebs solution and compared with the properties of porcine carotid arteries and ePTFE grafts. Attachment, proliferation and ingrowth of human smooth muscle cells (SMC) on the BC were analysed in vitro. The BC pellicle had an asymmetric structure composed of a fine network of nanofibrils similar to a collagen network. The shape of the stress-strain response of BC is reminiscent of the stress-strain response of the carotid artery, most probably due to the similarity in architecture of the nanofibrill networks. SMC adhered to and proliferated on the BC pellicle; an ingrowth of up to 40 microm was seen after 2 weeks of culture. BC exhibit attractive properties for use in future TEBV.

Epithelial regeneration from bioengineered skin explants in culture

BACKGROUND

Artificial skin substitutes are beneficial in the treatment of chronic wounds although their performance relative to authentic human skin is unclear.

OBJECTIVES

We compared the rate of outgrowth and morphology of neoepidermis from a bioengineered skin construct (Apligraf) with normal adult human skin explants on de-epidermized human dermal growth substrate with or without intact epidermal basement membrane zone.

METHODS

Epithelial outgrowth of air-exposed cultures in serum-supplemented keratinocyte medium was quantified by fluorescence imaging, morphology by light microscopy, biomarkers of keratinocyte activation, proliferation and migration by immunohistochemical analysis, and gelatinases by zymography.

RESULTS

Resurfacing from bioengineereed skin explants started earlier than from normal skin but subsequently, from day 3 to day 9, the rate of epidermalization from bioengineered skin was only 40% (206 +/- 23 microm day(-1), mean +/- SEM) of that of authentic skin (521 +/- 17 microm day(-1), P < 0.001). At culture termination at day 11, normal human skin had formed a multilayered and well-structured neoepidermis covering 41.0 +/- 1.2 mm2 of the dermal substrate while bioengineered skin produced a thinner, less organized epithelium covering 20.4 +/- 3.0 mm2. At this later stage, a higher expression of beta-defensin-2, keratin 16, Ki67 and matrix metalloproteinase (MMP)-9 was found in neoepidermis formed from authentic skin than from bioengineered skin. Activated MMP-2 was elevated in bioengineered skin-derived neoepidermis. Minor epithelial outgrowth was noted with either skin type on the dermal substrate devoid of basement membrane zone.

CONCLUSIONS

Cultured normal skin explants produced a more uniform and expansive in vivo-like neoepidermis than bioengineered skin explants.

Healing of PTFE Grafts in a Pig Model Recruit Neointimal Cells from Different Sources and Do Not Endothelialize

OBJECTIVES

The aim of this study was to analyze the cellular sources for the neointima and the cell type that is lining the lumen in artificial grafts implanted in pigs.

MATERIALS AND METHODS

We used polytetrafluoroethylene grafts as bypasses from the common to the external iliac arteries. The animals were sacrificed after 1, 4, 7, 14, 21, 30, 60 and 90 days. Morphological, immunohistochemical and electron microscope assessments were made.

RESULTS

After 7 days a circumferential neoadventitia was formed. At day 14 isolated cellular islets of proliferating cells were observed on the luminal side of the graft without connection to the neoadventitia or the adjacent arteries. In the anastomotic regions at day 14 we observed an isolated neointima in contact with the adjacent artery. The cells lining the lumen had characteristics of both smooth muscle cells and endothelial cells.

CONCLUSIONS

Our study suggests that in artificial porcine grafts, the perivascular tissue, the blood and the adjacent artery contribute to the formation of the neointima. The luminal surface is covered by a hybrid cell with both smooth muscle cell and endothelial cell properties.

Bioimaging TOF-SIMS of tissues by gold ion bombardment of a silver-coated thin section

The imaging time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) method was utilized to address the problem of cholesterol localization in rat tissues. Rat kidneys were fixed, cryoprotected by sucrose, frozen, sectioned by cryoultramicrotomy, and dried at room temperature. The samples were either covered with a thin silver layer or analyzed uncovered in an imaging TOF-SIMS instrument equipped with an Au1-3(+)-source. The yield of desorbed secondary ions for some species was up to 600-fold higher after silver coating of the samples. Reference samples of cholesterol were silver-coated and analyzed by TOF-SIMS to define significant peaks, specific for cholesterol. Such peaks were found at m/z = 386 (C27H46O+), m/z = 493 (C27H46O107Ag+), m/z = 495 (C27H46O109Ag+), m/z = 879 (C54H92O2 107Ag+), and m/z = 881 (C54H92O2 109Ag+). The silver-cationized cholesterol (493 < or = m/z < or = 495) signal was localized by imaging TOF-SIMS in the kidney sections and showed a high cholesterol content in the kidney glomeruli. A more diffuse distribution of cholesterol was also found over areas representing the cytoplasm or plasma membrane of the epithelial cells in the proximal tubules of rat kidney.

Hormonal regulation of glucose and system A amino acid transport in first trimester placental villous fragments

Alterations in placental nutrient transfer have been implicated in fetal growth abnormalities. In pregnancies complicated by diabetes and accelerated fetal growth, upregulations of glucose transporter 1 (GLUT1) and amino acid transporter system A have been shown in the syncytiotrophoblast of term placenta. In contrast, intrauterine growth restriction is associated with a downregulation of placental system A transporters. However, underlying mechanisms of transporter regulation are poorly understood, particularly in early pregnancy. In this study, hormonal regulation of placental glucose and system A transporters was investigated. The uptake of 3-O-[methyl-(14)C]-d-glucose was studied in villous fragments isolated from first trimester (6-13 wk of gestation) and term human placenta. Villous fragments were incubated in buffer containing insulin, leptin, cortisol, growth hormone (GH), prolactin, IGF-I, or under hypo/hyperglycemic conditions for 1 h. Subsequently, 3-O-[methyl-(14)C]-D-glucose uptake was measured with and without phloretin for 70 s in first trimester tissue and 20 s in term tissue. Methylaminoisobutyric uptake was measured with and without Na+ for 20 min. Glucose uptake was unaltered by hormones or hypo/hyperglycemia. GH decreased system A activity by 31% in first trimester (P < 0.05). The uptake of glucose was 50% higher in term compared with first trimester fragments and increased markedly between 6 and 13 wk of gestation (P < 0.05). We conclude that placental glucose transporter activity is not regulated by short exposures to the hormones or glucose concentrations tested. In contrast to term placental villous fragments, system A activity was not regulated by insulin or leptin in first trimester but was downregulated by GH.