Displaying publications 1 - 20 of 45 in total

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  1. The immunosuppressive effects of human bone marrow-derived mesenchymal stem cells target T cell proliferation but not its effector function
    Ramasamy R, Tong CK, Seow HF, Vidyadaran S, Dazzi F
    Cell Immunol, 2008 Feb;251(2):131-6.
    PMID: 18502411 DOI: 10.1016/j.cellimm.2008.04.009
    Mesenchymal stem cells (MSC) are non-haematopoietic stem cells that are capable of differentiating into tissues of mesodermal origin. MSC play an important role in supporting the development of fetal and adult haematopoiesis. More recently, MSC have also been found to exhibit inhibitory effect on T cell responses. However, there is little information on the mechanism of this immunosuppression and our study addresses this issue by targeting T cell functions at various level of immune responses. We have generated MSC from human adult bone marrow (BM) and investigated their immunoregulatory function at different phases of T cell responses. MSC showed the ability to inhibit mitogen (CD3/CD28 microbeads)-activated T cell proliferation in a dose-dependent manner. In order to evaluate the specificity of this immunosuppression, the proliferation of CD4(+) and CD8(+) cells were measured. MSC equally inhibit CD4(+) and CD8(+) subpopulations of T cells in response to PHA stimulation. However, the antiproliferative effect of MSC is not due to the inhibition of T cell activation. The expression of early activation markers of T cells, namely CD25 and CD69 were not significantly altered by MSC at 24, 48 and 72h. Furthermore, the immunosuppressive effect of MSC mainly targets T cell proliferation rather than their effector function since cytotoxicity of T cells is not affected. This work demonstrates that the immunosuppressive effect of MSC is exclusively a consequence of an anti-proliferative activity, which targets T cells of different subpopulations. For this reason, they have the potential to be exploited in the control of unwanted immune responses such as graft versus host disease (GVHD) and autoimmunity.
  2. Cytotoxicity and scanning electron microscopy study of gentamycin-coated HA effect on biofilm
    Au LF, Othman F, Mustaffa R, Vidyadaran S, Rahmat A, Besar I, et al.
    Med J Malaysia, 2008 Jul;63 Suppl A:16-7.
    PMID: 19024962
    Biofilms are adherent, multi-layered colonies of bacteria that are typically more resistant to the host immune response and routine antibiotic therapy. HA biomaterial comprises of a single-phased hydroxyapatite scaffold with interconnected pore structure. The device is designed as osteoconductive space filler to be gently packed into bony voids or gaps following tooth extraction or any surgical procedure. Gentamycin-coated biomaterial (locally made hydroxyapatite) was evaluated to reduce or eradicate the biofilm on the implant materials. The results indicated that the HA coated with gentamycin was biocompatible to human osteoblast cell line and the biofilm has been reduced after being treated with different concentrations of gentamycin-coated hydroxyapatite (HA).
  3. Mouse bone marrow mesenchymal stem cells acquire CD45-CD106+ immunophenotype only at later passages
    Ooi YY, Ramasamy R, Vidyadaran S
    Med J Malaysia, 2008 Jul;63 Suppl A:65-6.
    PMID: 19024986
    Classically, MSC are identified by a CD45-CD106+ phenotype. In this study, we found that mouse MSC achieve this characteristic phenotype only at later passages. With increasing passages, CD45 (hematopoietic marker) expression shifts to negativity, whereas CD106 (vascular cell adhesion molecule-1) expression becomes increasingly positive. These results demonstrate that MSC cells cultured from mouse bone marrow acquire a classical MSC immunophenotype (CD45-CD106+) in later passages.
  4. Effects of macrophage colony-stimulating factor on microglial responses to lipopolysaccharide and beta amyloid
    Vidyadaran S, Ooi YY, Subramaiam H, Badiei A, Abdullah M, Ramasamy R, et al.
    Cell Immunol, 2009;259(1):105-10.
    PMID: 19577228 DOI: 10.1016/j.cellimm.2009.06.005
    A challenge for studies involving microglia cultures is obtaining sufficient cells for downstream experiments. Macrophage colony-stimulating factor (M-CSF) has been used to improve yield of microglia in culture. However, the effects of M-CSF on activation profiles of microglia cultures are still unclear. Microglia activation is characterised by upregulation of co-stimulatory molecules and an inflammatory phenotype. The aim of this study is to demonstrate whether M-CSF supplementation alters microglial responses in resting and activated conditions. Microglia derived from mixed glia cultures and the BV-2 microglia cell line were cultivated with/without M-CSF and activated with lipopolysaccharide (LPS) and beta amyloid (Abeta). We show M-CSF expands primary microglia without affecting microglial responses to LPS and Abeta, as shown by the comparable expression of MHC class II and CD40 to microglia grown without this growth factor. M-CSF supplementation in BV-2 cells had no effect on nitric oxide (NO) production. Therefore, M-CSF can be considered for improving microglia yield in culture without introducing activation artefacts.
  5. Fulltext Mesenchymal stem cells inhibit proliferation of lymphoid origin haematopoietic tumour cells by inducing cell cycle arrest
    Sarmadi VH, Tong CK, Vidyadaran S, Abdullah M, Seow HF, Ramasamy R
    Med J Malaysia, 2010 Sep;65(3):209-14.
    PMID: 21939170
    We have previously shown that mesenchymal stem cells (MSC) inhibit tumour cell proliferation, thus promising a novel therapy for treating cancers. In this study, MSC were generated from human bone marrow samples and characterised based on standard immunophenotyping. When MSC were co-cultured with BV173 and Jurkat tumour cells, the proliferation of tumour cells were profoundly inhibited in a dose dependent manner mainly via cell to cell contact interaction. Further cell cycle analysis reveals that MSC arrest tumour cell proliferation in G0/G1 phase of cell cycle thus preventing the entry of tumour cells into S phase of cell cycle.
  6. Bone marrow-derived mesenchymal stem cells modulate BV2 microglia responses to lipopolysaccharide
    Ooi YY, Ramasamy R, Rahmat Z, Subramaiam H, Tan SW, Abdullah M, et al.
    Int Immunopharmacol, 2010 Dec;10(12):1532-40.
    PMID: 20850581 DOI: 10.1016/j.intimp.2010.09.001
    The immunoregulatory properties of mesenchymal stem cells (MSC) have been demonstrated on a wide range of cells. Here, we describe the modulatory effects of mouse bone marrow-derived MSC on BV2 microglia proliferation rate, nitric oxide (NO) production and CD40 expression. Mouse bone marrow MSC were co-cultured with BV2 cells at various seeding density ratios and activated with lipopolysaccharide (LPS). We show that MSC exert an anti-proliferative effect on microglia and are potent producers of NO when stimulated by soluble factors released by LPS-activated BV2. MSC suppressed proliferation of both untreated and LPS-treated microglia in a dose-dependent manner, significantly reducing BV2 proliferation at seeding density ratios of 1:0.2 and 1:0.1 (p
  7. Fulltext The effect of human mesenchymal stem cell on neutrophil oxidative burst
    Ramasamy, R., Krishna, K., Maqbool, M., Vellasamy, S., Sarmadi, V. H., Abdullah, M., et al.
    Malaysian Journal of Medicine and Health Sciences, 2010;6(2):11-17.
    MyJurnal
    Objective: Mesenchymal stem cells (MSC) are multipotent, non-haematopoietic stem cells that are
    capable of differentiating into different varieties of mature cell types such as osteoblasts, chondrocytes, adipocytes, and myoblasts. There is abundant evidence showing that MSC not only affect the differentiation of haematopoietic progenitors, but also the function of mature cells like lymphocytes and neutrophils. However the effect of MSC on neutrophil function and its responses is not well studied. Therefore, this study was conducted to assess the effect of MSC on neutrophil nitric oxide production. Method: Neutrophils from heparanised venous blood were isolated using Ficoll-Hypaque density gradient centrifugation followed by Dextran sedimentation and red blood cell (RBC) lysis. Isolated neutrophils were on average of 97% purity as determined by morphologic analysis. MSC were generated from human bone marrow and characterised by immunophenotyping (monoclonal antibodies CD105, CD73 and CD34) using a flowcytometer. In order to test the effects of MSC on neutrophil function, isolated neutrophils were co-cultured in the presence or absence of MSC at different ratios for 24 and 48 hours. The amount of nitric oxide released was used as an indication of oxidative burst and measured using the Griess assay. Result: The results indicate that MSC neither elevate the NO level when cocultured with resting neutrophils nor alone. However MSC profoundly inhibit the secretion of nitric oxide in PMA stimulated neutrophils after 24hr of incubation. Conclusion: MSC exert an immunomodulatory effect on neutrophil by suppressing neutrophil oxidative burst in vitro.
  8. Generation of mesenchymal stem cell from human umbilical cord tissue using a combination enzymatic and mechanical disassociation method
    Tong CK, Vellasamy S, Tan BC, Abdullah M, Vidyadaran S, Seow HF, et al.
    Cell Biol Int, 2011 Mar;35(3):221-6.
    PMID: 20946106 DOI: 10.1042/CBI20100326
    MSCs (mesenchymal stem cells) promise a great potential for regenerative medicine due to their unique properties of self-renewal, high plasticity, modulation of immune response and the flexibility for genetic modification. Therefore, the increasing demand for cellular therapy necessitates a larger-scale production of MSC; however, the technical and ethical issues had put a halt on it. To date, studies have shown that MSC could be derived from human UC (umbilical cord), which is once considered as clinical waste. We have compared the two conventional methods which are classic enzymatic digestion and explant method with our newly tailored enzymatic-mechanical disassociation method to generate UC-MSC. The generated UC-MSCs from the methods above were characterized based on their immunophenotyping, early embryonic transcription factors expression and mesodermal differentiation ability. Our results show that enzymatic-mechanical disassociation method increase the initial nucleated cell yield greatly (approximately 160-fold) and maximized the successful rate of UC-MSC generation. Enzymatic-mechanical disassociation-derived UC-MSC exhibited fibroblastic morphology and surface markers expression of CD105, CD73, CD29, CD90 and MHC class I. Furthermore, these cells constitutively express early embryonic transcription factors (Nanog, Oct-4, Sox-2 and Rex-1), as confirmed by RT-PCR, indicating their multipotency and high self-renewal capacity. They are also capable of differentiating into osteoblasts and adipocytes when given an appropriate induction. The present study demonstrates a new and efficient approach in generating MSC from UC, hence serving as ideal alternative source of mesenchymal stem cell for clinical and research use.
  9. Carica papaya increases regulatory T cells and reduces IFN-γ+ CD4+ T cells in healthy human subjects
    Abdullah M, Chai PS, Loh CY, Chong MY, Quay HW, Vidyadaran S, et al.
    Mol Nutr Food Res, 2011 May;55(5):803-6.
    PMID: 21520494 DOI: 10.1002/mnfr.201100087
    Fruit and vegetables have therapeutic potential as they dampen inflammation, have no known side-effects and as whole foods have prospective additive and synergistic benefits. Th1 (IFN-γ(+) CD4(+))/Th2 (IL-4(+)CD4(+)) T cells play a vital role in mediating inflammatory responses and may be regulated by regulatory T cells (Tregs). Effects of Carica papaya on cells of healthy individuals were determined using flow cytometry methods. Significant down-regulation of IFN-γ(+) CD4(+) (p=0.03, n=13), up-regulation of IL-4(+) CD4(+) (p=0.04, n=13) T cells and up-regulation of CD3(+) CD4(+) CD25(+) CD127(-) (p=0.001, n=15) Tregs were observed after papaya consumption. In vitro cultures showed up-regulation of Tregs in male subjects and was significantly associated with levels of IL-1β in culture supernatants (R(2) =0.608, p=0.04, n=12). Other inflammatory cytokines were significantly suppressed. Papaya consumption may exert an anti-inflammatory response mediated through Tregs and have potential in alleviating inflammatory conditions.
  10. Fulltext Optimisation of laboratory procedures for isolating human peripheral blood derived neutrophils
    Maqbool M, Vidyadaran S, George E, Ramasamy R
    Med J Malaysia, 2011 Oct;66(4):296-9.
    PMID: 22299545 MyJurnal
    Functional analysis of neutrophils requires isolation of these cells in the laboratory. Current isolation procedures are time consuming and can potentially activate the resting neutrophils. Thus, in this present study, we have optimised an existing laboratory protocol for human neutrophil isolation from peripheral blood. Twenty ml of blood samples were subjected to optimised density gradient separation and dextran sedimentation to obtain a pure population of neutrophils. The efficacy of the optimised manual post isolation of neutrophils was compared with pre isolation count performed by an automated haematology analyzer. The recovery of neutrophils via our optimised methods was 65.5% in comparison with neutrophils counts at pre-isolation. The morphological analysis of isolated neutrophils indicated the purity level more than 95% using Leishman staining. Our optimised laboratory procedures for neutrophils isolation successfully harvested neutrophils with good viability, purity and post recovery yield. This procedure provides an ideal platform to separate neutrophils for in vitro studies.
  11. Human mesenchymal stem cells protect neutrophils from serum-deprived cell death
    Maqbool M, Vidyadaran S, George E, Ramasamy R
    Cell Biol Int, 2011 Dec;35(12):1247-51.
    PMID: 21649586 DOI: 10.1042/CBI20110070
    We have previously shown that human MSC (mesenchymal stem cells) inhibit the proliferation of most of the immune cells. However, there are innate immune cells such as neutrophils and other PMN (polymorphonuclear) cells that do not require an extensive proliferation prior to their effector function. In this study, the effect of MSC on neutrophils in the presence of complete and serum-deprived culture media was investigated. In the presence of MSC, the viability of neutrophils increase as measured in 24 h of incubation at various supplementation of serum concentration. We have utilized Annexin V and PI (propidium iodide) staining to confirm whether the enhancement of neutrophil's viability is due to a reduction in PCD (programmed cell death). MSC significantly rescue neutrophils from apoptosis at 1, 5 and 10% of FBS (fetal bovine serum) supplementation. The fractions of viable and dead cells were increased and decreased respectively in the presence of MSC. Our results indicate MSC rescue neutrophils from nutrient- or serum-deprived cell death. However, whether this effect is exerted through a specific signalling pathway or confining neutrophils in resting state by MSC requires further investigation.
  12. Inhibitory effects of palm α-, γ- and δ-tocotrienol on lipopolysaccharide-induced nitric oxide production in BV2 microglia
    Tan SW, Ramasamy R, Abdullah M, Vidyadaran S
    Cell Immunol, 2011;271(2):205-9.
    PMID: 21839427 DOI: 10.1016/j.cellimm.2011.07.012
    Anti-inflammatory actions of the vitamin E fragment tocotrienol have not been described for microglia. Here, we screened palm α-, γ- and δ-tocotrienol isoforms and Tocomin® 50% (contains spectrum of tocotrienols and tocopherols) for their ability to limit nitric oxide (NO) production by BV2 microglia. Microglia were treated with varying doses of tocotrienols for 24h and stimulated with 1 μg/ml lipopolysaccharide (LPS). All tocotrienol isoforms reduced NO release by LPS-stimulated microglia, with 50 μM being the most potent tocotrienol dose. Of the isoforms tested, δ-tocotrienol lowered NO levels the most, reducing NO by approximately 50% at 48 h post-LPS treatment (p
  13. Cardamonin from Alpinia rafflesiana inhibits inflammatory responses in IFN-γ/LPS-stimulated BV2 microglia via NF-κB signalling pathway
    Chow YL, Lee KH, Vidyadaran S, Lajis NH, Akhtar MN, Israf DA, et al.
    Int Immunopharmacol, 2012 Apr;12(4):657-65.
    PMID: 22306767 DOI: 10.1016/j.intimp.2012.01.009
    The increasing prevalence of neurodegenerative diseases has prompted investigation into innovative therapeutics over the last two decades. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the therapeutic choices to control and suppress the symptoms of neurodegenerative diseases. However, NSAIDs-associated gastropathy has hampered their long term usage despite their clinical advancement. On the natural end of the treatment spectrum, our group has shown that cardamonin (2',4'-dihydroxy-6'-methoxychalcone) isolated from Alpinia rafflesiana exerts potential anti-inflammatory activity in activated macrophages. Therefore, we further explored the anti-inflammatory property of cardamonin as well as its underlying mechanism of action in IFN-γ/LPS-stimulated microglial cells. In this investigation, cardamonin shows promising anti-inflammatory activity in microglial cell line BV2 by inhibiting the secretion of pro-inflammatory mediators including nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). The inhibition of NO and PGE(2) by cardamonin are resulted from the reduced expression of inducible nitric oxide synthase (iNOS) and cycloxygenase-2 (COX-2), respectively. Meanwhile the suppressive effects of cardamonin on TNF-α, IL-1β and IL-6 were demonstrated at both protein and mRNA levels, thus indicating the interference of upstream signal transduction pathway. Our results also validate that cardamonin interrupts nuclear factor-kappa B (NF-κB) signalling pathway via attenuation of NF-κB DNA binding activity. Interestingly, cardamonin also showed a consistent suppressive effect on the cell surface expression of CD14. Taken together, our experimental data provide mechanistic insights for the anti-inflammatory actions of cardamonin in BV2 and thus suggest a possible therapeutic application of cardamonin for targeting neuroinflammatory disorders.
  14. Isolation and characterisation of mesenchymal stem cells derived from human placenta tissue
    Vellasamy S, Sandrasaigaran P, Vidyadaran S, George E, Ramasamy R
    World J Stem Cells, 2012 Jun 26;4(6):53-61.
    PMID: 22993662
    To explore the feasibility of placenta tissue as a reliable and efficient source for generating mesenchymal stem cells (MSC).
  15. Fulltext Omega 3 polyunsaturated fatty acid improves spatial learning and hippocampal peroxisome proliferator activated receptors (PPARα and PPARγ) gene expression in rats
    Hajjar T, Meng GY, Rajion MA, Vidyadaran S, Othman F, Farjam AS, et al.
    BMC Neurosci, 2012;13:109.
    PMID: 22989138 DOI: 10.1186/1471-2202-13-109
    This study examined the effects of dietary polyunsaturated fatty acids (PUFA) as different n-6: n-3 ratios on spatial learning and gene expression of peroxisome- proliferator-activated receptors (PPARs) in the hippocampus of rats. Thirty male Sprague-Dawley rats were randomly allotted into 3 groups of ten animals each and received experimental diets with different n-6: n-3 PUFA ratios of either 65:1, 22:1 or 4.5:1. After 10 weeks, the spatial memory of the animals was assessed using the Morris Water Maze test. The expression of PPARα and PPARγ genes were determined using real-time PCR.
  16. Gender effect on in vitro lymphocyte subset levels of healthy individuals
    Abdullah M, Chai PS, Chong MY, Tohit ER, Ramasamy R, Pei CP, et al.
    Cell Immunol, 2012;272(2):214-9.
    PMID: 22078320 DOI: 10.1016/j.cellimm.2011.10.009
    Differences in gender immune response have resulted in differences in immune protection and susceptibility to inflammatory diseases. Cultured peripheral blood mononuclear cells (PBMC) are widely used in immunomodulation studies, yet the influence of gender is usually not considered. We examined the effect of in vitro culture and phytohaemagglutinin (PHA) stimulation on PBMC lymphocyte subsets using flowcytometry. Full blood counts of whole blood showed higher levels of lymphocyte in male subjects. Lymphocyte subsets enumeration revealed higher NK cell counts in males and higher B cells in females. Cultured PBMC resulted in significant increases in B and total T cell percentages among females and NK cells among males. PHA stimulated significantly increased percentages of NK and total T cells in males and total activated T cells (CD69+) in females. Our results showed significant gender differences in lymphocyte subsets in cultured conditions. This may affect experimental outcome.
  17. Fulltext Immunophenotype and differentiation capacity of bone marrow-derived mesenchymal stem cells from CBA/Ca, ICR and Balb/c mice
    Ooi YY, Rahmat Z, Jose S, Ramasamy R, Vidyadaran S
    World J Stem Cells, 2013 Jan 26;5(1):34-42.
    PMID: 23362438 DOI: 10.4252/wjsc.v5.i1.34
    To assess the capacity to isolate and expand mesenchymal stem cells (MSC) from bone marrow of CBA/Ca, ICR and Balb/c mice.
  18. Mesenchymal stem cells of human placenta and umbilical cord suppress T-cell proliferation at G0 phase of cell cycle
    Vellasamy S, Sandrasaigaran P, Vidyadaran S, Abdullah M, George E, Ramasamy R
    Cell Biol Int, 2013 Mar;37(3):250-6.
    PMID: 23364902 DOI: 10.1002/cbin.10033
    Mesenchymal stem cells (MSC) generated from human umbilical cord (UC-MSC) and placenta (PLC-MSC) were assessed and compared for their immunomodulatory function on T cells proliferation by analysis of the cell cycle. Mitogen stimulated or resting T cells were co-cultured in the presence or absence of MSC. T-cell proliferation was assessed by tritiated thymidine ((3) H-TdR) assay and the mechanism of inhibition was examined bycell cycle and apoptosis assay. Both UC-MSC and PLC-MSC profoundly inhibited the proliferation of T-cell, mainly via cell-to-cell contact. MSC-mediated anti-proliferation does not lead to apoptosis,but prevented T cells from entering S phase and they therefore accumulated in the G(0) /G(1) phases. The anti-proliferative activity of MSC was related to this cell cycle arrest of T-cell. UC-MSC produced a greater inhibition than PLC-MSC in all measured parameters.
  19. Fulltext A three-dimensional collagen construct to model lipopolysaccharide-induced activation of BV2 microglia
    Haw RT, Tong CK, Yew A, Lee HC, Phillips JB, Vidyadaran S
    J Neuroinflammation, 2014 Jul 30;11:134.
    PMID: 25074682 DOI: 10.1186/1742-2094-11-134
    BACKGROUND: We report a novel method of culturing microglia in three dimension (3D) using collagen as a substrate. By culturing microglia within a matrix, we aim to emulate the physical state of microglia embedded within parenchyma.

    METHODS: BV2 microglia cell suspensions were prepared with type I collagen and cast into culture plates. To characterise the BV2 microglia cultured in 3D, the cultures were evaluated for their viability, cell morphology and response to lipopolysaccharide (LPS) activation. Conventional monolayer cultures (grown on uncoated and collagen-coated polystyrene) were set up concurrently for comparison.

    RESULTS: BV2 microglia in 3D collagen matrices were viable at 48 hrs of culture and exhibit a ramified morphology with multiplanar cytoplasmic projections. Following stimulation with 1 μg/ml LPS, microglia cultured in 3D collagen gels increase their expression of nitric oxide (NO) and CD40, indicating their capacity to become activated within the matrix. Up to 97.8% of BV2 microglia grown in 3D cultures gained CD40 positivity in response to LPS, compared to approximately 60% of cells grown in a monolayer (P

  20. Fulltext The neuroprotective effects of tocotrienol rich fraction and alpha tocopherol against glutamate injury in astrocytes
    Selvaraju TR, Khaza'ai H, Vidyadaran S, Abd Mutalib MS, Vasudevan R
    Bosn J Basic Med Sci, 2014 Nov 16;14(4):195-204.
    PMID: 25428670 DOI: 10.17305/bjbms.2014.4.91
    Tocotrienol rich fraction (TRF) is an extract of palm oil, which consists of 25% alpha tocopherol (α-TCP) and 75% tocotrienols. TRF has been shown to possess potent antioxidant, anti-inflammatory, anticancer, neuroprotection, and cholesterol lowering activities. Glutamate is the main excitatory amino acid neurotransmitter in the central nervous system of mammalian, which can be excitotoxic, and it has been suggested to play a key role in neurodegenerative disorders like Parkinson's and Alzheimer's diseases. In this present study, the effects of vitamin E (TRF and α-TCP) in protecting astrocytes against glutamate injury were elucidated. Astrocytes induced with 180 mM of glutamate lead to significant cell death. However, glutamate mediated cytotoxicity was diminished via pre and post supplementation of TRF and α-TCP. Hence, vitamin E acted as a potent antioxidant agent in recovering mitochondrial injury due to elevated oxidative stress, and enhanced better survivability upon glutamate toxicity.
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