Amsterdam, Netherlands
Amsterdam, Netherlands
Time filter
Source Type

van Beuge M.M.,University of Groningen | Prakash J.,University of Groningen | Prakash J.,University of Twente | Lacombe M.,Kreatech Diagnostics | And 4 more authors.
PLoS ONE | Year: 2013

Transforming growth factor-β (TGF-β) is a major pro-fibrotic cytokine, causing the overproduction of extracellular matrix molecules in many fibrotic diseases. Inhibition of its type-I receptor (ALK5) has been shown to effectively inhibit fibrosis in animal models. However, apart from its pro-fibrotic effects, TGF-β also has a regulatory role in the immune system and influences tumorigenesis, which limits the use of inhibitors. We therefore explored the cell-specific delivery of an ALK5-inhibitor to hepatic stellate cells, a key cell in the development of liver fibrosis. We synthesized a conjugate of the ALK5-inhibitor LY-364947 coupled to mannose-6-phosphate human serum albumin (M6PHSA), which binds to the insulin-like growth factor II receptor on activated HSC. The effectivity of the conjugate was evaluated in primary HSC and in an acute liver injury model in mice. In vitro, the free drug and the conjugate significantly inhibited fibrotic markers in HSC. In hepatocytes, TGF-β-dependent signaling was inhibited by free drug, but not by the conjugate, thus showing its cell-specificity. In vivo, the conjugate localized in desmin-positive cells in the liver and not in hepatocytes or immune cells. In the acute liver injury model in mice, the conjugate reduced fibrogenic markers and collagen deposition more effectively than free drug. We conclude that we can specifically deliver an ALK5-inhibitor to HSC using the M6PHSA carrier and that this targeted drug reduces fibrogenic parameters in vivo, without affecting other cell-types. © 2013 van Beuge et al.

Van Beuge M.M.,University of Groningen | Prakash J.,University of Groningen | Lacombe M.,Kreatech Diagnostics | Gosens R.,University of Groningen | And 4 more authors.
Journal of Pharmacology and Experimental Therapeutics | Year: 2011

One of the pathways activated during liver fibrosis is the Rho kinase pathway, which regulates activation, migration, and contraction of hepatic stellate cells (HSC). Inhibition of this kinase by the Rho kinase inhibitor Y27632 [(+)-(R)-trans- 4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride] has been shown to reduce fibrosis in animal models. However, kinase expression is ubiquitous, so any inhibitor may affect many cell types. We hypothesize that cell-specific delivery of a kinase inhibitor will be beneficial. Therefore, we conjugated Y27632 to the carrier mannose-6-phosphate (M6P) human serum albumin (HSA), which is taken up specifically in activated HSC through the M6P/insulin-like growth factor II receptor. This conjugate decreased protein expression of phosphorylated myosin light chain 2 (pMLC2) and vinculin, downstream of Rho kinase, in activated primary HSC and decreased the migration and contraction of HSC. In an ex vivo model, free Y27632 decreased contractility of rat aortas, whereas the Y27-conjugate did not, showing that the Y27-conjugate does not affect nontarget tissue. In chronic CCl 4-induced liver fibrosis, both free drug and conjugate reduced HSC activation; however, only the Y27-conjugate significantly reduced collagen deposition. Treatment with the Y27-conjugate, but not with free drug, reduced pMLC2 expression in livers 24 h after injection, demonstrating prolonged inhibition of the Rho kinase pathway. The Rho kinase inhibitor Y27632 can be specifically targeted to HSC using M6PHSA, decreasing its effects in nontarget tissues. The targeted drug effectively reduced fibrotic parameters in vivo via the inhibition of the Rho kinase pathway. Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics.

Van Beuge M.M.,University of Groningen | Prakash J.,University of Groningen | Lacombe M.,Kreatech Diagnostics | Post E.,University of Groningen | And 3 more authors.
Pharmaceutical Research | Year: 2011

Purpose: Rho-kinase regulates activation of hepatic stellate cells (HSC) during liver fibrosis, but the ubiquitous presence of this kinase may hinder examination of its exact role and the therapeutic use of inhibitors. We therefore coupled the Rho-kinase inhibitor Y27632 to a drug carrier that binds the mannose-6-phosphate insulin-like growth factor II (M6P/IGFII)-receptor which is upregulated on activated HSC. Methods: Y27632 was coupled to mannose-6-phosphate human serum albumin (M6PHSA), and in vitro experiments were performed on primary rat HSC. Biodistribution and effect studies were performed in an acute CCl 4 model in mice. Results: Y27-conjugate remained stable in serum, while drug was efficiently released in liver homogenates. Receptor-blocking studies revealed that it was specifically taken up through the M6P/IGFII-receptor on fibroblasts, and it inhibited expression of fibrotic markers in activated HSC. In vivo, liver drug levels were significantly higher after injection of Y27-conjugate as compared to Y27632, and the conjugate accumulated specifically in HSC. After acute CCl 4-induced liver injury, Y27-conjugate reduced the local activation of HSC, whereas an equimolar dose of free drug did not. Conclusions: We conclude that specific targeting of a Rho-kinase inhibitor to HSC leads to enhanced accumulation of the drug in HSC, reducing early fibrogenesis in the liver. © 2011 The Author(s).

Ioannou D.,University of Kent | Meershoek E.J.,Kreatech Diagnostics | Thornhill A.R.,University of Kent | Thornhill A.R.,Gynaecology and Genetics Center | And 2 more authors.
Molecular and Cellular Probes | Year: 2011

From the late 1980s onwards, the use of DNA probes to visualise sequences on individual chromosomes (fluorescent in-situ hybridisation - FISH) revolutionised the study of cytogenetics. Following single colour experiments, more fluorochromes were added, culminating in a 24 colour assay that could distinguish all human chromosomes. Interphase cytogenetics (the detection of chromosome copy number in interphase nuclei) soon followed, however 24 colour experiments are hampered for this application as mixing fluorochromes to produce secondary colours produces images that are not easily distinguishable from overlapping signals. This study reports the development and use of a novel protocol, new fast hybridising FISH probes, and a bespoke image capture system for the assessment of chromosome copy number in interphase nuclei. The multicolour probe sets can be used individually or in sequential hybridisation layers to assess ploidy of all 24 human chromosomes in the same nucleus. Applications of this technique are in the investigation of chromosome copy number and the assessment of nuclear organisation for a range of different cell types including human sperm, cancer cells and preimplantation embryos. © 2011 Elsevier Ltd.

Ioannou D.,University of Kent | Ioannou D.,London Bridge Fertility Gynaecology and Genetics Center | Meershoek E.J.,Kreatech Diagnostics | Christopikou D.,Embryogenesis IVF Unit | And 4 more authors.
Chromosome Research | Year: 2011

Organisation of chromosome territories in interphase nuclei has been studied in many systems and positional alterations have been associated with disease phenotypes (e.g. laminopathies, cancer) in somatic cells. Altered nuclear organisation is also reported in developmental processes such as mammalian spermatogenesis where a "chromocentre" model is proposed with the centromeres and sex chromosomes repositioning to the nuclear centre. The purpose of this study was to test the hypothesis that alterations in nuclear organisation of human spermatozoa are associated with defects upstream in spermatogenesis (as manifest in certain infertility phenotypes). The nuclear address of (peri-) centromeric loci for 18 chromosomes (1-4, 6-12, 15-18, 20, X and Y) was assayed in 20 males using established algorithms for 3D extrapolations of 2D data. The control group comprised 10 fertile sperm donors while the test group was 10 patients with severely compromised semen parameters including high sperm aneuploidy. All loci examined in the control group adopted defined, interior positions thus providing supporting evidence for the presence of a chromocentre and interior sex chromosome territories. In the test group however there were subtle alterations in the nuclear address for certain centromeres in individual patients and, when all patient results were pooled, some different nuclear addresses were observed for chromosomes 3, 6, 12 and 18. Considering the extensive impairment of spermatogenesis in the test group (evidenced by compromised semen parameters and increased chromosome abnormalities), the observed differences in nuclear organisation for centromeric loci compared to the controls were modest. A defined pattern of nuclear reorganisation of centromeric loci in sperm heads therefore appears to be a remarkably robust process, even if spermatogenesis is severely compromised. © 2011 Springer Science+Business Media B.V.

Pauly F.,Lund University | Dexlin-Mellby L.,Lund University | Ek S.,Lund University | Ohlin M.,Lund University | And 6 more authors.
Journal of Proteome Research | Year: 2013

Proteomics, the large-scale analysis of proteins, is a rapidly evolving field with an increasing number of key clinical applications, such as diagnosis, prognosis, and classification. In order to generate complete protein expression profiles, or protein atlases, any crude sample format must be addressable in a rapid, multiplex, and sensitive manner. A common and clinically central sample format, formalin-fixed, paraffin-embedded (FFPE) tissue material, holds great potential as a source for disease-associated biomarker signatures. However, despite major efforts, extraction and subsequent profiling of proteins from FFPE tissue has proven to be challenging. In this proof-of-concept study, we have demonstrated for the first time that proteins could be extracted, labeled, and subsequently profiled in a multiplex, sensitive, and reproducible manner using recombinant scFv antibody microarrays. Thus, we have added FFPE samples to the list of sample formats available for high-throughput analysis by affinity proteomics, paving the way for the next generation of biomarker-driven discovery projects. © 2013 American Chemical Society.

Ioannou D.,University of Kent | Fonseka K.G.L.,University of Kent | Meershoek E.J.,Kreatech Diagnostics | Thornhill A.R.,Genetics Center | And 3 more authors.
Chromosome Research | Year: 2012

Fluorescence in situ hybridisation (FISH) was first applied on in vitro fertilisation (IVF) embryos for the preimplantation genetic diagnosis of sex, then chromosome translocations and later for chromosome copy number (PGS). Because of the controversy surrounding PGS diagnostically, it has been replaced by array-based approaches; however, FISH remains a powerful tool for investigating mechanisms of both postzygotic segregation error and nuclear organisation, especially if most or all of the chromosomes in the karyotype can be analysed. The purpose of this study was to develop and apply a 24 chromosome FISH assay to investigate chromosome-specific rates of gain and loss, nuclear organisation patterns and the veracity of the original PGS result in days 5-6 human embryos. Analysis of 17 embryos by this newly developed approach gave strong signals for all chromosomes; it revealed chromosome copy number for each human chromosome per cell for each embryo and the nuclear address of the (mostly centromeric) loci probed. As all embryos were surplus to IVF requirements for both transfer and freezing (and many had an abnormal PGS indication) expected high levels of chromosome abnormalities were seen and no single nucleus displayed a normal complement; all were mosaic. Certain patterns emerged, however, namely that chromosome loss was more common than gain and apparent mitotic nondisjunction. Moreover, the centromeric probes tended preferentially to occupy the nuclear centre. Where we had a prior day 3 biopsy PGS result, it was confirmed, in part, by 24 colour FISH in most but not all cases. © Springer Science+Business Media B.V. 2012.

Loading Kreatech Diagnostics collaborators
Loading Kreatech Diagnostics collaborators