Ag2 S Biocompatible Ensembles as Dual OCT Contrast Agents and NIR Ocular Imaging Probes.

Ag2 S nanoparticles (NPs) emerge as a unique system that simultaneously features in vivo near-infrared (NIR) imaging, remote heating, and low toxicity thermal sensing. In this work, their capabilities are extended into the fields of optical coherence tomography (OCT), as contrast agents, and NIR probes in both ex vivo and in vivo experiments in eyeballs. The new dual property for ocular imaging is obtained by the preparation of Ag2 S NPs ensembles with a biocompatible amphiphilic block copolymer. Rather than a classical ligand exchange, where surface traps may arise due to incomplete replacement of surface sites, the use of this polymer provides a protective extra layer that preserves the photoluminescence properties of the NPs, and the procedure allows for the controlled preparation of submicrometric scattering centers. The resulting NPs ensembles show extraordinary colloidal stability with time and biocompatibility, enhancing the contrast in OCT with simultaneous NIR imaging in the second biological window.

Four-Year Outcome of XEN 45 Gel Stent Implantation in a Swedish Population.

Purpose: To report the long-time success rate of XEN 45 gel stent implantation in a Scandinavian population. Patients and Methods: This was a retrospective single-center analysis of all patients undergoing XEN 45 stent surgery between December 2015 and May 2017. The main outcome was success rate according to several definitions of success. Subgroup analysis was performed. Secondary outcomes were change in intraocular pressure (IOP) and number of IOP-lowering agents. Need for secondary glaucoma surgery, needling rate and complications were recorded. Results: A total of 103 eyes could be evaluated after four years. Mean age was 70.6 years. Primary open-angle glaucoma (POAG) accounted for 46.6% and exfoliative glaucoma (PEXG) for 39.8%. Mean IOP dropped from 24.0 to 15.9 mmHg (p<0.001) and IOP-lowering agents from 3.5 to 1.5 (p<0.001). The success rate with individual target pressures after four years was 43.7%. Secondary glaucoma surgery was performed in 45 (43.7%) of cases. Combined cases (n=12) were not statistically different to stand-alone procedures (p=0.28). No difference between PEXG and POAG could be detected (p=0.44). During the learning curve, stent misplacement was common and resulted in worse outcome for less experienced surgeons. Conclusion: The overall success rate of XEN 45 gel stent surgery in the present cohort is relatively low in a long-time follow-up under the given circumstances if all initial patients are included to follow-up. The influence of the surgeon's learning curve is obvious, and improvement in success can be expected when used by experienced and high-volume surgeons. No significant differences were found in PEXG compared to POAG or in XEN surgery combined with cataract surgery compared to stand-alone.

The first step into phenolic metabolism in the hornwort Anthoceros agrestis: molecular and biochemical characterization of two phenylalanine ammonia-lyase isoforms.

MAIN CONCLUSION: Two isoforms of phenylalanine ammonia-lyase (PAL) have been isolated as cDNA sequences from the hornwort Anthoceros agrestis. The encoded enzymes convert L-phenylalanine and to lower extents L-tyrosine and L-histidine. Thus, the functional presence of the general phenylpropanoid pathway in one of the earliest land plant groups is established. The hornwort Anthoceros agrestis has an elaborated phenolic metabolism resulting in phenolic compounds, such as rosmarinic acid or megacerotonic acid. The general phenylpropanoid pathway is involved in the biosynthesis of these compounds. Two phenylalanine ammonia-lyase (PAL) genes, AaPAL1 and AaPAL2, have been identified in Anthoceros agrestis and the protein with an N-terminal 6xHis-tag heterologously synthesized in Escherichia coli for a full biochemical characterization. Both PAL proteins accept L-phenylalanine, L-tyrosine as well as L-histidine as substrates, although the activity is explicitly the highest with L-phenylalanine. Km values as well as catalytic efficiencies were determined for phenylalanine (Km AaPAL1 39 µM, AaPAL2 18 µM) and tyrosine (Km AaPAL1 3.3 mM, AaPAL2 3.5 mM). In suspension cultures of Anthoceros agrestis, PAL genes were transcribed in parallel to rosmarinic acid (RA) accumulation and both showed highest abundance in the early growth phase. In a phylogenetic tree, both AaPAL amino acid sequences grouped within a clade with PAL amino acid sequences of diverse origin ranging from non-vascular to vascular plants, while most PALs from eudicots and monocots were mainly found in two other clades. The similarity of the hornwort PAL amino acid sequences to PAL sequences from vascular plants is more than 80% showing a strong conservation within the land plants. With this characterization of PALs from Anthoceros agrestis together with former investigations concerning cinnamic acid 4-hydroxylase and 4-coumaric acid CoA-ligase, the functional presence of the general phenylpropanoid pathway in this hornwort is proven.

Receptive Vocabulary of Children With Bilateral Cochlear Implants From 3 to 16 Years of Age.

OBJECTIVES: The vocabulary of children with cochlear implants is often smaller than that of their peers with typical hearing, but there is uncertainty regarding the extent of the differences and potential risks and protective factors. Some studies indicate that their receptive vocabulary develops well at first, but that they fail to keep up with their typical hearing peers, causing many CI users to enter school with a receptive vocabulary that is not age-appropriate. To better understand the receptive vocabulary abilities of children with cochlear implants this study explored age-related differences to matched children with typical hearing and associations between vocabulary skills and child-level characteristics. DESIGN: A retrospective cross-sectional study with matched controls was conducted at the Norwegian national cochlear implant center at Oslo University Hospital. Eighty-eight children (mean age 8.7 years; range 3.2 to 15.9; 43 girls, 45 boys) who had received bilateral cochlear implants before 3 years of age were compared with two groups of children with typical hearing. One group was matched for maternal education, sex, and chronological age, the other group was matched for maternal education, sex, and hearing age. Receptive vocabulary performance was measured with the British Picture Vocabulary Scale. RESULTS: Cochlear implant users' receptive vocabulary was poorer than that of age-matched children with typical hearing ( M = 84.6 standard points, SD = 21.1; children with typical hearing: M = 102.1 standard points, SD = 15.8; mean difference -17.5 standard points, 95% CI [-23.0 to -12.0], p < 0.001; Hedges's g = -0.94, 95% CI [-1.24 to -0.62]), and children with cochlear implants were significantly more likely to perform below the normative range (risk ratio = 2.2, 95% CI [1.42 to 3.83]). However, there was a significant nonlinear U-shaped effect of age on the scores of cochlear implant users, with the difference to the matched typical hearing children being largest (23.9 standard points, on average) around 8.7 years of age and smaller toward the beginning and end of the age range. There was no significant difference compared with children with typical hearing when differences in auditory experience were accounted for. Variability was not significantly different between the groups. Further analysis with a random forest revealed that, in addition to chronological age and hearing age, simultaneous versus sequential implantation, communication mode at school, and social integration were predictors of cochlear implant users' receptive vocabulary. CONCLUSIONS: On average, the receptive vocabulary of children with cochlear implants was smaller than that of their typical hearing peers. The magnitude of the difference was changing with age and was the largest for children in early primary school. The nonlinear effect of age might explain some of the ambiguity in previous research findings and could indicate that better intervention is required around school entry. The results emphasize that continuous monitoring and support are crucial to avoid far-reaching negative effects on the children's development and well-being.

Identification and biochemical characterisation of tyrosine aminotransferase from Anthoceros agrestis unveils the conceivable entry point into rosmarinic acid biosynthesis in hornworts.

MAIN CONCLUSION: Tyrosine aminotransferase (AaTAT) from the hornwort Anthoceros agrestis Paton (Anthocerotaceae) was amplified and expressed in E. coli. The active enzyme is able to accept a wide range of substrates with distinct preference for L-tyrosine, therefore, possibly catalysing the initial step in rosmarinic acid biosynthesis. The presence of rosmarinic acid (RA) in the hornwort A. agrestis is well known, and some attempts have been made to clarify the biosynthesis of this caffeic acid ester in lower plants. Parallel to the biosynthesis in vascular plants, the involvement of tyrosine aminotransferase (EC 2.6.1.5; TAT) as the initial step was assumed. The amplification of a nucleotide sequence putatively encoding AaTAT (Genbank MN922307) and expression in E. coli were successful. The enzyme proved to have a high acceptance of L-tyrosine (Km 0.53 mM) whilst slightly preferring 2-oxoglutarate over phenylpyruvate as co-substrate. Applying L-phenylalanine as a potential amino donor or using oxaloacetate or pyruvate as a replacement for 2-oxoglutarate as amino acceptor resulted in significantly lower catalytic efficiencies in each of these cases. To facilitate further substrate search, two methods were introduced, one using ninhydrin after thin-layer chromatography and the other using derivatisation with o-phthalaldehyde followed by HPLC or LC-MS analysis. Both methods proved to be well applicable and helped to confirm the acceptance of further aromatic and aliphatic amino acids. This work presents the first description of a heterologously expressed TAT from a hornwort (A. agrestis) and describes the possible entry into the biosynthesis of RA and other specialised compounds in a so far neglected representative of terrestrial plants and upcoming new model organism.

Learning Curve and One-Year Outcome of XEN 45 Gel Stent Implantation in a Swedish Population.

PURPOSE: Evaluation of 1-year-outcome of XEN 45 gel stent surgery in a Swedish cohort with regard to clinical success, complications, and learning curve. PATIENTS AND METHODS: This was a retrospective study of glaucoma patients undergoing glaucoma XEN-stent surgery alone or combined with phacoemulsification between December 2015 and May 2017. Intraocular pressure (IOP), number of medical agents, and adverse events were assessed. Clinical success rate was defined as achieving individual target pressure with/without medication. RESULTS: A total of 113 eyes were included in the final statistics. Mean age was 70.8±11.8 years. Primary open angle glaucoma (POAG) accounted for 46.9% and exfoliative glaucoma (PEXG) for 40.7%. Mean preoperative IOP was 23.8±6.2 mmHg and mean number of agents 3.4. After 1 year, mean IOP was reduced to 16.1±4.7 mmHg and medication to 1.34 substances on average. Failure rate at 1-year follow-up was 34% with no significant difference between POAG and PEXG. There was a trend of higher success rate for combined cases (P=0.116). Stents with malpositioned or curved appearance had significantly worse outcome. The failure rate of the most productive surgeon dropped from 33% to 10% from the first implantations. Temporary hypotony (19.5%) and choroidal detachment (9.7%) were the most common complications. Blockage of the inner stent lumen was common (8.8%), with a high proportion of failure. CONCLUSION: XEN-stent surgery is a surgical option in uncontrolled glaucoma in both POAG and PEXG. A XEN-stent can reduce both IOP and the number of antiglaucoma medications needed. The learning curve is significant and stent positioning is crucial for optimal results. Combined XEN-cataract surgery is not inferior to stand-alone procedures. The long-time effectiveness is still to be proven.

Long-Term Language Development in Children With Early Simultaneous Bilateral Cochlear Implants.

OBJECTIVES: This longitudinal study followed the language development of children who received the combination of early (5 to 18 months) and simultaneous bilateral cochlear implants (CIs) throughout the first 6 years after implantation. It examined the trajectories of their language development and identified factors associated with language outcomes. DESIGN: Participants were 21 Norwegian children who received bilateral CIs between the ages of 5 and 18 mo and 21 children with normal hearing (NH) who were matched to the children with CIs on age, sex, and maternal education. The language skills of these two groups were compared at 10 time points (3, 6, 9, 12, 18, 24, 36, 48, 60, and 72 months after implantation) using parent reports and standardized measures of general language skills, vocabulary, and grammar. In addition, assessments were made of the effects of age at CI activation, speech recognition abilities, and mothers' education on language outcomes 6 years after implantation. RESULTS: During the first 4 years after implantation, the gap in general expressive and receptive language abilities between children with CIs and children with NH gradually closed. While at the initial five to six assessments (3 to 36 months after implantation), significant differences between children with CIs and children with NH were observed; at 4 years after implantation, there were no longer any significant group differences in general language skills and most children with CIs achieved scores within 1 SD of the tests' normative means. From 2 to 3 years after implantation onward, expressive vocabulary and receptive grammar skills of children with CIs were similar to those of the reference group. However, from 4 years after implantation until the end of the observation period, 6 years after implantation, expressive grammar skills of children with CIs were lower than those of children with NH. In addition, a gap in receptive vocabulary appeared and grew increasingly larger from 4 to 6 years postimplantation. At the final assessment, the children with CIs had an average receptive vocabulary score around 1 SD below the normative mean. Regression analysis indicated that the children's language outcomes at 6 years after implantation were related to their speech recognition skills, age at CI activation, and maternal education. CONCLUSIONS: In the first 4 years after implantation, the language performance of children with CIs became increasingly similar to that of their NH peers. However, between 4 and 6 years after implantation, there were indications of challenges with certain aspects of language, specifically receptive vocabulary and expressive grammar. Because these challenges first appeared after the 4-year assessment, the findings underline the importance of long-term language intervention to increase the chances of a continued language development comparable to that of NH peers. They also indicate that there is a need for comprehensive longitudinal studies of the language development of children with CIs beyond 4 years after implantation.

Cochlear Implant Data Logs Predict Children's Receptive Vocabulary.

OBJECTIVES: The data logs of Cochlear Nucleus cochlear implant (CI) sound processors show large interindividual variation in children's daily CI use and auditory environments. This study explored whether these differences are associated with differences in the receptive vocabulary of young implanted children. DESIGN: Data of 52 prelingually deaf children, who had received a CI before 3 years of age, were obtained from their clinical records. In total, 73 Peabody Picture Vocabulary tests and CI data logs for 1 year preceding each test were collected. The data logs were used to determine the children's average daily amount of CI use and exposure to speech, speech in noise, noise, music, and quiet. In addition, information was collected about other potential predictors of language abilities, namely gender, age, age at implantation, etiology of deafness, educational placement, and implantation mode (unilateral, bilateral). Model selection with Akaike's information criterion was used to determine which data-logging metrics, other variables, and combinations of both best predict receptive vocabulary scores. RESULTS: The data showed a strong positive association between receptive vocabulary and daily CI use, and a negative association between receptive vocabulary and daily exposure to music. Associations with the data logs' speech and noise metrics were less clear. The most important other variable was educational placement. The best model performance was achieved when data logs and other information were combined. CONCLUSIONS: The results emphasize the importance of consistent CI use and a rich auditory environment for the early language development of young CI users. The study also shows that CI data logs capture information about children's environment and CI use that are related to language performance and can help to detect and address problems and improve the auditory rehabilitation after cochlear implantation.

Correlation and agreement between Language ENvironment Analysis (LENA™) and manual transcription for Dutch natural language recordings.

The Language ENvironment Analysis system (LENA™) automatically analyzes the natural sound environments of children. Among other things, it estimates the amounts of adult words (AWC), child vocalizations (CV), conversational turns (CT), and electronic media (TV) that a child is exposed to. To assess LENA's reliability, we compared it to manual transcription. Specifically, we calculated the correlation and agreement between the LENA estimates and manual counts for 48 five-min audio samples. These samples were selected from eight day-long recordings of six Dutch-speaking children (ages 2-5). The correlations were strong for AWC, r = . 87, and CV, r = . 77, and comparatively low for CT, r = . 52, and TV, r = . 50. However, the agreement analysis revealed a constant bias in AWC counts, and proportional biases for CV and CT (i.e., the bias varied with the values for CV and CT). Agreement for detecting electronic media was poor. Moreover, the limits of agreement were wide for all four metrics. That is, the differences between LENA and the manual transcriptions for individual audio samples varied widely around the mean difference. This variation could indicate that LENA was affected by differences between the samples that did not equally affect the human transcribers. The disagreements and biases cast doubt on the comparability of LENA measurements across families and time, which is crucial for using LENA in research. Our sample is too small to conclude within which limits LENA's measurements are comparable, but it seems advisable to be cautious of factors that could systematically bias LENA's performance and thereby create confounds.

Auditory Environment Across the Life Span of Cochlear Implant Users: Insights From Data Logging.

Purpose: We describe the natural auditory environment of people with cochlear implants (CIs), how it changes across the life span, and how it varies between individuals. Method: We performed a retrospective cross-sectional analysis of Cochlear Nucleus 6 CI sound-processor data logs. The logs were obtained from 1,501 people with CIs (ages 0-96 years). They covered over 2.4 million hr of implant use and indicated how much time the CI users had spent in various acoustical environments. We investigated exposure to spoken language, noise, music, and quiet, and analyzed variation between age groups, users, and countries. Results: CI users spent a substantial part of their daily life in noisy environments. As a consequence, most speech was presented in background noise. We found significant differences between age groups for all auditory scenes. Yet even within the same age group and country, variability between individuals was substantial. Conclusions: Regardless of their age, people with CIs face challenging acoustical environments in their daily life. Our results underline the importance of supporting them with assistive listening technology. Moreover, we found large differences between individuals' auditory diets that might contribute to differences in rehabilitation outcomes. Their causes and effects should be investigated further.

Under the hood of statistical learning: A statistical MMN reflects the magnitude of transitional probabilities in auditory sequences.

Within the framework of statistical learning, many behavioural studies investigated the processing of unpredicted events. However, surprisingly few neurophysiological studies are available on this topic, and no statistical learning experiment has investigated electroencephalographic (EEG) correlates of processing events with different transition probabilities. We carried out an EEG study with a novel variant of the established statistical learning paradigm. Timbres were presented in isochronous sequences of triplets. The first two sounds of all triplets were equiprobable, while the third sound occurred with either low (10%), intermediate (30%), or high (60%) probability. Thus, the occurrence probability of the third item of each triplet (given the first two items) was varied. Compared to high-probability triplet endings, endings with low and intermediate probability elicited an early anterior negativity that had an onset around 100 ms and was maximal at around 180 ms. This effect was larger for events with low than for events with intermediate probability. Our results reveal that, when predictions are based on statistical learning, events that do not match a prediction evoke an early anterior negativity, with the amplitude of this mismatch response being inversely related to the probability of such events. Thus, we report a statistical mismatch negativity (sMMN) that reflects statistical learning of transitional probability distributions that go beyond auditory sensory memory capabilities.

Economic considerations related to choice of intraocular lens (IOL) and posterior capsule opacification frequency - a comparison of three different IOLs.

PURPOSE: To evaluate the posterior capsule opacification (PCO) rates in three different modern standard intraocular lenses (IOL) and analyse the related cost. METHODS: Retrospective study of medical records from 1527 patients who underwent uneventful cataract surgery by phacoemulsification with posterior chamber implantation of either AcrySof SN60 (n = 375), Akreos Adapt (n = 350) or Tecnis Acryl IOL (n = 801). All surgeries were performed by the same surgeon using the same surgical technique and equipment. Primary end-point was neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy for visual impairment secondary to PCO. Cost of IOL material and Nd:YAG capsulotomy for PCO was then evaluated and compared between the IOLs. RESULTS: Mean follow-up was 41.5 months, and the only statistically significant variable of developing PCO was IOL type and individual follow-up time. Nd:YAG capsulotomy was performed in 7.47% in the AcrySof group, 17.71% in the Akreos group and 3.75% in the Tecnis group. Average cost for Nd:YAG capsulotomy per surgery was €18.75 in the AcrySof SN60 group, €44.25 in the Akreos Adapt group and €9.25 in the Tecnis Acryl group. The combined cost of cataract surgery and PCO treatment was €9.81 higher in for the Akreos Adapt group than the other two combined. CONCLUSIONS: This retrospective study shows that the risk of PCO and Nd:YAG capsulotomy is significantly higher in hydrophilic Akreos IOL compared with both AcrySof and Tecnis hydrophobic IOLs. The increased risk of PCO in the hydrophilic IOL is related to higher total average costs for cataract surgery.

Effects of keratin phosphorylation on the mechanical properties of keratin filaments in living cells.

Keratin filaments impart resilience against mechanical extension of the cell. Despite the pathophysiological relevance of this function, very little is known about the mechanical properties of intermediate filaments in living cells and how these properties are modulated. We used keratin mutants that mimic or abrogate phosphorylation of keratin 8-serine(431) and keratin 18-serine(52) and investigated their effect on keratin tortuousness after cell stretch release in squamous cell carcinoma cells. Cells transfected with the wild-type keratins were used as controls. We can show that keratin dephosphorylation alters the stretch response of keratin in living cells since keratin tortuousness was abolished when phosphorylation of keratin18-serine(52) was abrogated. Additional experiments demonstrate that keratin tortuousness is not simply caused by a plastic overextension of keratin filaments because tortuousness is reversible and requires an intact actin-myosin system. The role of actin in this process remains unclear, but we suggest anchorage of keratin filaments to actin during stretch that leads to buckling on stretch release. Dephosphorylated keratin18-serine(52) might strengthen the recoil force of keratin filaments and hence explain the abolished buckling. The almost exclusive immunolabeling for phosphorylated keratin18-serine (52) in the cell periphery points at a particular role of the peripheral keratin network in this regard.

Keratin 8 phosphorylation regulates keratin reorganization and migration of epithelial tumor cells.

Cell migration and invasion are largely dependent on the complex organization of the various cytoskeletal components. Whereas the role of actin filaments and microtubules in cell motility is well established, the role of intermediate filaments in this process is incompletely understood. Organization and structure of the keratin cytoskeleton, which consists of heteropolymers of at least one type 1 and one type 2 intermediate filament, are in part regulated by post-translational modifications. In particular, phosphorylation events influence the properties of the keratin network. Sphingosylphosphorylcholine (SPC) is a bioactive lipid with the exceptional ability to change the organization of the keratin cytoskeleton, leading to reorganization of keratin filaments, increased elasticity, and subsequently increased migration of epithelial tumor cells. Here we investigate the signaling pathways that mediate SPC-induced keratin reorganization and the role of keratin phosphorylation in this process. We establish that the MEK-ERK signaling cascade regulates both SPC-induced keratin phosphorylation and reorganization in human pancreatic and gastric cancer cells and identify Ser431 in keratin 8 as the crucial residue whose phosphorylation is required and sufficient to induce keratin reorganization and consequently enhanced migration of human epithelial tumor cells.

Elastic moduli of living epithelial pancreatic cancer cells and their skeletonized keratin intermediate filament network.

In simple epithelia, such as living epithelial pancreatic cancer cells (Panc-1), unusual amounts of keratin filaments can be found, which makes these cells an ideal model system to study the role of keratin for cell mechanical properties. In this work, the elastic moduli of Panc-1 cells and their extracted in-situ subcellular keratin intermediate filament network are determined and compared with each other. For this, the living adherent cells and their extracted keratin network were probed with local quasistatic indentation testing during large deformations using the Atomic Force Microscope (AFM). We determined the elastic modulus of the skeletonized but structurally intact keratin network to be in the order of 10 Pa, while the living cell elastic modulus ranged from 100 to 500 Pa. By removing microfilaments, microtubules, membranes and soluble cytoplasmic components during keratin network extraction, we excluded effects caused by crosslinking with other filamentous fibers and from the viscosity of the cytoplasm. Thus, the determined elastic modulus equals the actual elastic modulus inherent to such a keratin filamentous network. In our assessment of the effective mechanical contribution of the architecturally intact, skeletonized keratin network to living cell mechanics, we come to the conclusion that it plays only a very limited role. Evidently, the quantitative dominance of keratin in these cells does not reflect a strong influence on determining the cell's elastic modulus. Instead, keratin like other filamentous structures in the cell's scaffolding, e.g., F-actin and microtubuli, is one part of a greater whole.

Mechanical strain of alveolar type II cells in culture: changes in the transcellular cytokeratin network and adaptations.

Mechanical forces exert multiple effects in cells, ranging from altered protein expression patterns to cell damage and death. Despite undisputable biological importance, little is known about structural changes in cells subjected to strain ex vivo. Here, we undertake the first transmission electron microscopy investigation combined with fluorescence imaging on pulmonary alveolar type II cells that are subjected to equibiaxial strain. When cells are investigated immediately after stretch, we demonstrate that curved cytokeratin (CK) fibers are straightened out at 10% increase in cell surface area (CSA) and that this is accompanied by a widened extracellular gap of desmosomes-the insertion points of CK fibers. Surprisingly, a CSA increase by 20% led to higher fiber curvatures of CK fibers and a concurrent return of the desmosomal gap to normal values. Since 20% CSA increase also induced a significant phosphorylation of CK8-ser431, we suggest CK phosphorylation might lower the tensile force of the transcellular CK network, which could explain the morphological observations. Stretch durations of 5 min caused membrane injury in up to 24% of the cells stretched by 30%, but the CK network remained surprisingly intact even in dead cells. We conclude that CK and desmosomes constitute a strong transcellular scaffold that survives cell death and hypothesize that phosphorylation of CK fibers is a mechano-induced adaptive mechanism to maintain epithelial overall integrity.

The bioactive lipid sphingosylphosphorylcholine induces differentiation of mouse embryonic stem cells and human promyelocytic leukaemia cells.

Sphingosylphosphorylcholine (SPC) is the major component of high-density lipoproteins (HDL) in blood plasma. The bioactive lipid acts mainly via G protein coupled receptors (GPCRs). Similar to ligands of other GPCRs, SPC has multiple biological roles including the regulation of proliferation, migration, angiogenesis, wound healing and heart rate. Lysophospholipids and their receptors have also been implicated in cell differentiation. A potential role of SPC in stem cell or tumour cell differentiation has been elusive so far. Here we examined the effect of SPC on the differentiation of mouse embryonic stem (ES) cells and of human NB4 promyelocytic leukemia cells, a well established tumour differentiation model. Our data show that mouse embryonic stem cells and NB4 cells express the relevant GPCRs for SPC. We demonstrate both at the level of morphology and of gene expression that SPC induces neuronal and cardiac differentiation of mouse ES cells. Furthermore, SPC induces differentiation of NB4 cells by a mechanism which is critically dependent on the activity of the MEK-ERK cascade. Thus, the bioactive lipid SPC is a novel differentiation inducing agent both for mouse ES cells, but also of certain human tumour cells.