Showing papers by "Sai Kiang Lim published in 2014"

Mesenchymal stem cells secrete immunologically active exosomes.

Abstract: Mesenchymal stem cells (MSCs) have been shown to secrete exosomes that are cardioprotective. Here, we demonstrated that MSC exosome, a secreted membrane vesicle, is immunologically active. MSC exosomes induced polymyxin-resistant, MYD88-dependent secreted embryonic alkaline phosphatase (SEAP) expression in a THP1-Xblue, a THP-1 reporter cell line with an NFκB-SEAP reporter gene. In contrast to lipopolysaccharide, they induced high levels of anti-inflammatory IL10 and TGFβ1 transcript at 3 and 72 h, and much attenuated levels of pro-inflammatory IL1B, IL6, TNFA and IL12P40 transcript at 3-h. The 3-h but not 72-h induction of cytokine transcript was abrogated by MyD88 deficiency. Primary human and mouse monocytes exhibited a similar exosome-induced cytokine transcript profile. Exosome-treated THP-1 but not MyD88-deficient THP-1 cells polarized activated CD4+ T cells to CD4+CD25+FoxP3+ regulatory T cells (Tregs) at a ratio of one exosome-treated THP-1 cell to 1,000 CD4+ T cells. Infusion of MSC exosomes enha...

Mesenchymal stem cell-derived exosomes promote hepatic regeneration in drug-induced liver injury models

Abstract: Mesenchymal stem cell-conditioned medium (MSC-CM) has been shown to have protective effects against various cellular-injury models. This mechanism of protection, however, has yet to be elucidated. Recently, exosomes were identified as the active component in MSC-CM. The aim of this study is to investigate the effect of MSC-derived exosomes in an established carbon tetrachloride (CCl4)-induced liver injury mouse model. This potential effect is then validated by using in vitro xenobiotic-induced liver-injury assays: (1) acetaminophen (APAP)- and (2) hydrogen peroxide (H2O2)-induced liver injury. The exosomes were introduced concurrent with CCl4 into a mouse model through different routes of administration. Biochemical analysis was performed based on the blood and liver tissues. Subsequently the exosomes were treated in APAP and H2O2-toxicants with in vitro models. Cell viability was measured, and biomarkers indicative of regenerative and oxidative biochemical responses were determined to probe the mechanism of any hepatoprotective activity observed. In contrast to mice treated with phosphate-buffered saline, CCl4 injury in mice was attenuated by concurrent-treatment exosomes, and characterized by an increase in hepatocyte proliferation, as demonstrated with proliferating cell nuclear antigen (PCNA) elevation. Significantly higher cell viability was demonstrated in the exosomes-treated group compared with the non-exosome-treated group in both injury models. The higher survival rate was associated with upregulation of the priming-phase genes during liver regeneration, which subsequently led to higher expression of proliferation proteins (PCNA and cyclin D1) in the exosomes-treated group. Exosomes also inhibited the APAP- and H2O2-induced hepatocytes apoptosis through upregulation of Bcl-xL protein expression. However, exosomes do not mitigate hepatocyte injury via modulation of oxidative stress. In summary, these results suggest that MSC-derived exosomes can elicit hepatoprotective effects against toxicants-induced injury, mainly through activation of proliferative and regenerative responses.

Immunotherapeutic potential of extracellular vesicles.

Abstract: Extracellular vesicles or EVs is a term that encompasses all classes of secreted lipid membrane vesicles. Despite being scientific novelties, EVs are gaining importance as a mediator of important physiological and pathological intercellular activities possibly through the transfer of their cargo of protein and RNA between cells. In particular, exosomes the currently best characterized EVs have been notable for their in vitro and in vivo immunomodulatory activities. Exosomes are nanometer-sized endosome-derived vesicles secreted by many cell types and their immunomodulatory potential is independent of their cell source. Besides immune cells such as dendritic cells, macrophages and T cells, cancer and stem cells also secrete immunologically active exosomes that could influence both physiological and pathological processes. The immunological activities of exosomes affect both innate and adaptive immunity and include antigen presentation, T cell activation, T cell polarisation to Tregs, immune suppression and anti-inflammation. As such, exosomes carry much immunotherapeutic potential as a therapeutic agent and a therapeutic target.

Spectroscopic detection of exogenous materials in latent fingerprints treated with powders and lifted off with adhesive tapes

Abstract: Fingerprint evidence offers great value to criminal investigations since it is an internationally recognized and established means of human identification. With recent advances in modern technology, scientists have started analyzing not only the ridge patterns of fingerprints but also substances which can be found within them. The aim of this work was to determine whether Fourier transform infrared (FTIR) spectromicroscopy could be used to detect contamination in a fingerprint which was dusted with powder (a technique already recognized as an effective and reliable method for developing latent fingerprints) and subsequently lifted off with adhesive tape. Explosive materials (pentaerythritol tetranitrate, C-4, TNT) and noncontrolled substances (sugar, aspirin) were used to prepare contaminated fingerprints on various substrates. Freshly deposited fingermarks with powders which were lifted off with adhesive tapes (provided by Singapore Police Force) were analyzed using a Bruker Hyperion 2000 microscope at the ISMI beamline (Singapore Synchrotron Light Source) with an attenuated total reflection objective. FTIR spectroscopy is a nondestructive technique which requires almost no sample preparation. Further, the fingerprint under analysis remains in pristine condition, allowing subsequent analysis if necessary. All analyzed substances were successfully distinguished using their FTIR spectra in powdered and lifted fingerprints. This method has the potential to significantly impact forensic science by greatly enhancing the information that can be obtained from the study of fingerprints.

Plasma biomarker discovery in preeclampsia using a novel differential isolation technology for circulating extracellular

Abstract: CholeratoxinBchain(CTB)andannexinV(AV)whichrespectivelybindsGM1gangliosideandphosphatidylserinewereusedtoisolateextracellularvesiclesfromplasmaofPEpatientsandhealthypregnant women. The proteins in the vesicles were identified usingenzyme-linked immunosorbent assay, antibody array, and massspectrometry.

Pre-eclampsia biomarkers

Abstract: We describe a method of detecting pre-eclampsia in a cell, tissue, organ or organism, the method comprising detecting a modulated level of expression, activity or amount of a pre-eclampsia biomarker polypeptide selected from the group consisting of PlGF, FLT1, BNP, ANP, CD9, PAI-1, TGF β, PCT, SI 00b, TIMP1, CD 105 and IL6 in or of a microparticle type (selected from a CTB binding microparticle and an Annexin V binding microparticle) from the cell, tissue, organ or organism, as compared to level of expression, activity or amount of the pre-eclampsia biomarker polypeptide in the same microparticle type in a cell, tissue, organ or organism not sufferin from pre-eclampsia.

***WITHDRAWN PATENT AS PER THE LATEST USPTO WITHDRAWN LIST***Mesenchymal stem cell conditioned medium

Abstract: We disclose a method of preparing a conditioned cell culture medium, the method comprising the steps of: (a) culturing a mesenchymal stem cell (MSC), a descendent thereof or a cell line derived therefrom in a cell culture medium; and (b) optionally isolating the cell culture medium; in which the mesenchymal stem cell (MSC) is obtained by propagating a cell obtained by dispersing a embryonic stem (ES) cell colony, or a descendent thereof, in the absence of co-culture in a serum free medium comprising FGF2.