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Misunderstanding of Leptospirosis

Teh SW, Mok PL, Subbiah SK

Acta Trop, 2019 09;197:105046.
PMID: 31158342 DOI: 10.1016/j.actatropica.2019.105046
Fulltext Colonization of Methicillin-Resistant Staphylococcus aureus (MRSA) among Medical Students in Tertiary Institution in Central Malaysia

Rampal S, Zainuddin NH, Elias NA, Tengku Jamaluddin TZM, Maniam S, Teh SW, et al.

Antibiotics (Basel), 2020 Jul 06;9(7).
PMID: 32640588 DOI: 10.3390/antibiotics9070382

Methicillin-resistant Staphylococcus aureus or MRSA infection is virulent and presents with a broad spectrum of severity. Limited regional reports that specifically outlined the potential risk of medical students being part of the dissemination of MRSA in healthcare settings were noted. This study aims to assess the prevalence and contributory factors of colonization of MRSA on neckties, headscarves, and ID badges among medical students in a local medical university in Malaysia. A cross-sectional study was conducted involving 256 medical students. A validated questionnaire was used to collect the data, and sample swabs were collected between July and August 2013 by swabbing neckties, headscarves, or identification badges. The swabs were then streaked onto mannitol salt agar (MSA) and incubated at 37 °C overnight. Out of 433 samples taken, 40 swabs (9.24%) were positive for Staphylococcus aureus. Out of the 40 swabs, five (12.5%) isolates were MRSA (one culture was isolated from the headscarf of a preclinical student, one culture was isolated from the necktie of clinical students, while the remaining three were isolated from identification badges of clinical students. There was no significant association between age, gender, ethnicity, and phase of medical students with the colonization of MRSA (p > 0.05). There was a significant association between knowledge score on hand hygiene practice and phase of medical students. MRSA colonies were present on neckties, headscarves, and identification badges of medical students of all phases. The findings from this study suggest the need for improvement of hand hygiene knowledge and discontinuity of mandatory use of physical ID badges and neckties among medical students.
Bone breaking infections - A focus on bacterial and mosquito-borne viral infections

Cui YC, Wu Q, Teh SW, Peli A, Bu G, Qiu YS, et al.

Microb Pathog, 2018 Sep;122:130-136.
PMID: 29909241 DOI: 10.1016/j.micpath.2018.06.021

The recent global resurgence of arthritogenic alphaviruses, including Ross River, chikungunya, and dengue, highlights an urgency for the development of therapeutic strategies. Currently, dengue represents the most rapidly transmitting mosquito-borne viral disease worldwide. By contracting bone breaking diseases, patients experience devastating clinical manifestations involving muscle pain and bone loss. The bone self-repair and regeneration mechanisms can be damaged by the presence of viruses and bacteria. The rapid establishment of dengue epidemic and the severity of bacterial and viral infections affecting the bone stress the urgent need of developing effective interventions. Herein, we review current knowledge on bone breaking infections, covering both bacterial and mosquito-borne viral ones. The mechanisms exploited by these diseases to significantly affect the bone, including interferences with self-repair and regeneration routes, were discussed. In the final section, challenges for future research aimed to treat and prevent bacterial and mosquito-borne bone-breaking infections have been outlined.
Biomimetic hydroxyapatite/poly xylitol sebacic adibate/vitamin K nanocomposite for enhancing bone regeneration

Dai Z, Dang M, Zhang W, Murugan S, Teh SW, Pan H

Artif Cells Nanomed Biotechnol, 2019 Dec;47(1):1898-1907.
PMID: 31066314 DOI: 10.1080/21691401.2019.1573183

Hydroxyapatite (HAP) is a significant bone mineral that establishes bone strength. HAP composites in combination with biodegradable and bioactive polymer poly xylitol sebacic adipate (PXSA) would result in a constant release at target sites. Numerous studies have shown that vitamin K (VK) might possess a vital function in bone metabolism. The purpose of the present study was to inspect the synthesized composite HAP/PXSA/VK in developing polymeric biomaterials composite for the application of bone tissue regeneration. FTIR, X-ray diffraction, SEM and TEM techniques were applied to characterize the prepared composites. The release of VK from the HAP/PXSA/VK composite was evidenced through UV-Vis spectroscopy. In vitro studies proved that the HAP/PXSA/VK composite is appropriate for mesenchymal stem cell culture. Compared to pure HAP prepared following the same method, HAP/PXSA/VK composite provided favourable microstructures and good biodegradation distinctiveness for the application of tissue engineering, as well as tissue in-growth characteristics and improved scaffold cell penetration. This work reveals that the HAP/PXSA/VK composites have the potential for applications in bone tissue engineering.
Fulltext Mechanisms of Oral Bacterial Virulence Factors in Pancreatic Cancer

Sun Z, Xiong C, Teh SW, Lim JCW, Kumar S, Thilakavathy K

Front Cell Infect Microbiol, 2019;9:412.
PMID: 31867287 DOI: 10.3389/fcimb.2019.00412

Pancreatic cancer is a highly lethal disease, and most patients remain asymptomatic until the disease enters advanced stages. There is lack of knowledge in the pathogenesis, effective prevention and early diagnosis of pancreatic cancer. Recently, bacteria were found in pancreatic tissue that has been considered sterile before. The distribution of flora in pancreatic cancer tissue was reported to be different from normal pancreatic tissue. These abnormally distributed bacteria may be the risk factors for inducing pancreatic cancer. Therefore, studies on combined effect of multi-bacterial and multi-virulence factors may add to the knowledge of pancreatic cancer pathogenesis and aid in designing new preventive and therapeutic strategies. In this review, we outlined three oral bacteria associated with pancreatic cancer and their virulence factors linked with cancer.
Recent updates on phthalate exposure and human health: a special focus on liver toxicity and stem cell regeneration

Praveena SM, Teh SW, Rajendran RK, Kannan N, Lin CC, Abdullah R, et al.

Environ Sci Pollut Res Int, 2018 Apr;25(12):11333-11342.
PMID: 29546515 DOI: 10.1007/s11356-018-1652-8

Phthalates have been blended in various compositions as plasticizers worldwide for a variety of purposes. Consequently, humans are exposed to a wide spectrum of phthalates that needs to be researched and understood correctly. The goal of this review is to focus on phthalate's internal exposure pathways and possible role of human digestion on liver toxicity. In addition, special focus was made on stem cell therapy in reverting liver toxicity. The known entry of higher molecular weight phthalates is through ingestion while inhalation and dermal pathways are for lower molecular weight phthalates. In human body, certain phthalates are digested through phase 1 (hydrolysis, oxidation) and phase 2 (conjugation) metabolic processes. The phthalates that are made bioavailable through digestion enter the blood stream and reach the liver for further detoxification, and these are excreted via urine and/or feces. Bis(2-ethylhexyl) phthalate (DEHP) is a compound well studied involving human metabolism. Liver plays a pivotal role in humans for detoxification of pollutants. Thus, continuous exposure to phthalates in humans may lead to inhibition of liver detoxifying enzymes and may result in liver dysfunction. The potential of stem cell therapy addressed herewith will revert liver dysfunction and lead to restoration of liver function properly.
Fulltext Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 transfection of guide RNA targeting on MMP9 as anti-cancer therapy in human cutaneous squamous cell carcinoma cell line A431

Teh SW, Elderdery A, Rampal S, Subbiah SK, Mok PL

Contemp Oncol (Pozn), 2023;27(4):255-262.
PMID: 38405210 DOI: 10.5114/wo.2023.135364

INTRODUCTION: Cutaneous squamous cell carcinoma (SCC) is the second most common form of skin malignancy, representing around 20% of all skin cancers. It is the main cause of death due to non-melanoma skin cancer every year. Metastatic cutaneous SCC is associated with poor prognosis in patients and warrants a more effective and specific approach such as disruption of genes associated with cancer metastasis.
MATERIAL AND METHODS: Matrix metalloproteinases (MMPs) are enzymes involved in cancer progression and are regarded as major oncotargets. Among others, MMP9 plays critical roles in tumour progression, angiogenesis, and invasion of cutaneous SCC. We aimed to determine whether the MMP9 gene is a suitable gene target for anti-cancer therapy for cutaneous SCC. We performed clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 transfection of guide RNA (gRNA) targeting the MMP9 gene into human cutaneous SCC cell line A431.
RESULTS: Following CRISPR transfection treatment, the viability (p < 0.01) and migratory activities (p < 0.0001) of in vitro cutaneous SCC cells were found to be reduced significantly. The use of quantitative polymerase chain reaction (qPCR) also revealed downregulation of the mRNA expression levels of cancer-promoting genes TGF-β, FGF, PI3K, VEGF-A, and vimentin. Direct inhibition of the MMP9 gene was shown to decrease survivability and metastasis of cutaneous SCC cell line A431.
CONCLUSIONS: Our findings provided direct evidence that MMP9 is important in the viability, proliferation, and metastasis of cutaneous SCC cells. It serves as a positive foundation for future CRISPR-based targeted anti-cancer therapies in treating skin cancer and other forms of malignancies that involve MMPs as the key determinants.
Fulltext Hypoxia in Bone and Oxygen Releasing Biomaterials in Fracture Treatments Using Mesenchymal Stem Cell Therapy: A Review

Teh SW, Koh AE, Tong JB, Wu X, Samrot AV, Rampal S, et al.

Front Cell Dev Biol, 2021;9:634131.
PMID: 34490233 DOI: 10.3389/fcell.2021.634131

Bone fractures have a high degree of severity. This is usually a result of the physical trauma of diseases that affect bone tissues, such as osteoporosis. Due to its highly vascular nature, the bone is in a constant state of remodeling. Although those of younger ages possess bones with high regenerative potential, the impact of a disrupted vasculature can severely affect the recovery process and cause osteonecrosis. This is commonly seen in the neck of femur, scaphoid, and talus bone. In recent years, mesenchymal stem cell (MSC) therapy has been used to aid in the regeneration of afflicted bone. However, the cut-off in blood supply due to bone fractures can lead to hypoxia-induced changes in engrafted MSCs. Researchers have designed several oxygen-generating biomaterials and yielded varying degrees of success in enhancing tissue salvage and preserving cellular metabolism under ischemia. These can be utilized to further improve stem cell therapy for bone repair. In this review, we touch on the pathophysiology of these bone fractures and review the application of oxygen-generating biomaterials to further enhance MSC-mediated repair of fractures in the three aforementioned parts of the bone.
Fulltext Recent Updates on Treatment of Ocular Microbial Infections by Stem Cell Therapy: A Review

Teh SW, Mok PL, Abd Rashid M, Bastion MC, Ibrahim N, Higuchi A, et al.

Int J Mol Sci, 2018 Feb 13;19(2).
PMID: 29438279 DOI: 10.3390/ijms19020558

Ocular microbial infection has emerged as a major public health crisis during the past two decades. A variety of causative agents can cause ocular microbial infections; which are characterized by persistent and destructive inflammation of the ocular tissue; progressive visual disturbance; and may result in loss of visual function in patients if early and effective treatments are not received. The conventional therapeutic approaches to treat vision impairment and blindness resulting from microbial infections involve antimicrobial therapy to eliminate the offending pathogens or in severe cases; by surgical methods and retinal prosthesis replacing of the infected area. In cases where there is concurrent inflammation, once infection is controlled, anti-inflammatory agents are indicated to reduce ocular damage from inflammation which ensues. Despite advances in medical research; progress in the control of ocular microbial infections remains slow. The varying level of ocular tissue recovery in individuals and the incomplete visual functional restoration indicate the chief limitations of current strategies. The development of a more extensive therapy is needed to help in healing to regain vision in patients. Stem cells are multipotent stromal cells that can give rise to a vast variety of cell types following proper differentiation protocol. Stem cell therapy shows promise in reducing inflammation and repairing tissue damage on the eye caused by microbial infections by its ability to modulate immune response and promote tissue regeneration. This article reviews a selected list of common infectious agents affecting the eye; which include fungi; viruses; parasites and bacteria with the aim of discussing the current antimicrobial treatments and the associated therapeutic challenges. We also provide recent updates of the advances in stem cells studies on sepsis therapy as a suggestion of optimum treatment regime for ocular microbial infections.
Metabolic utilization of human osteoblast cell line hFOB 1.19 under normoxic and hypoxic conditions: A phenotypic microarray analysis

Cui YC, Qiu YS, Wu Q, Bu G, Peli A, Teh SW, et al.

Exp Biol Med (Maywood), 2021 May;246(10):1177-1183.
PMID: 33535809 DOI: 10.1177/1535370220985468

Osteoblasts play an important role in bone regeneration and repair. The hypoxia condition in bone occurs when bone undergoes fracture, and this will trigger a series of biochemical and mechanical changes to enable bone repair. Hence, it is interesting to observe the metabolites and metabolism changes when osteoblasts are exposed to hypoxic condition. This study has looked into the response of human osteoblast hFOB 1.19 under normoxic and hypoxic conditions by observing the cell growth and utilization of metabolites via Phenotype MicroArrays™ under these two different oxygen concentrations. The cell growth of hFOB 1.19 under hypoxic condition showed better growth compared to hFOB 1.19 under normal condition. In this study, osteoblast used glycolysis as the main pathway to produce energy as hFOB 1.19 in both hypoxic and normoxic conditions showed cell growth in well containing dextrin, glycogen, maltotriose, D-maltose, D-glucose-6-phospate, D-glucose, D-mannose, D-Turanose, D-fructose-6-phosphate, D-galactose, uridine, adenosine, inosine and α-keto-glutaric acid. In hypoxia, the cells have utilized additional metabolites such as α-D-glucose-1-phosphate and D-fructose, indicating possible activation of glycogen synthesis and glycogenolysis to metabolize α-D-glucose-1-phosphate. Meanwhile, during normoxia, D-L-α-glycerol phosphate was used, and this implies that the osteoblast may use glycerol-3-phosphate shuttle and oxidative phosphorylation to metabolize glycerol-3-phosphate.
Looking into dental pulp stem cells in the therapy of photoreceptors and retinal degenerative disorders

Alsaeedi HA, Lam C, Koh AE, Teh SW, Mok PL, Higuchi A, et al.

J. Photochem. Photobiol. B, Biol., 2020 Jan;203:111727.
PMID: 31862637 DOI: 10.1016/j.jphotobiol.2019.111727

Blindness and vision impairment are caused by irremediable retinal degeneration in affected individuals worldwide. Cell therapy for a retinal replacement can potentially rescue their vision, specifically for those who lost the light sensing photoreceptors in the eye. As such, well-characterized retinal cells are required for the replacement purposes. Stem cell-based therapy in photoreceptor and retinal pigment epithelium transplantation is well received, however, the drawbacks of retinal transplantation is the limited clinical protocols development, insufficient number of transplanted cells for recovery, the selection of potential stem cell sources that can be differentiated into the target cells, and the ability of cells to migrate to the host tissue. Dental pulp stem cells (DPSC) belong to a subset of mesenchymal stem cells, and are recently being studied due to its high capability of differentiating into cells of the neuronal lineage. In this review, we look into the potential uses of DPSC in treating retinal degeneration, and also the current data supporting its application.
Fulltext Stem Cell Therapy in Dengue Virus-Infected BALB/C Mice Improves Hepatic Injury

Sakinah S, Priya SP, Mok PL, Munisvaradass R, Teh SW, Sun Z, et al.

Front Cell Dev Biol, 2021;9:637270.
PMID: 34291043 DOI: 10.3389/fcell.2021.637270

Extensive clinical efforts have been made to control the severity of dengue diseases; however, the dengue morbidity and mortality have not declined. Dengue virus (DENV) can infect and cause systemic damage in many organs, resulting in organ failure. Here, we present a novel report showing a tailored stem-cell-based therapy that can aid in viral clearance and rescue liver cells from further damage during dengue infection. We administered a combination of hematopoietic stem cells and endothelial progenitor cells in a DENV-infected BALB/c mouse model and found that delivery of this cell cocktail had improved their liver functions, confirmed by hematology, histopathology, and next-generation sequencing. These stem and progenitor cells can differentiate into target cells and repair the damaged tissues. In addition, the regime can regulate endothelial proliferation and permeability, modulate inflammatory reactions, enhance extracellular matrix production and angiogenesis, and secrete an array of growth factors to create an enhanced milieu for cell reparation. No previous study has been published on the treatment of dengue infection using stem cells combination. In conclusion, dengue-induced liver damage was rescued by administration of stem cell therapy, with less apoptosis and improved repair and regeneration in the dengue mouse model.
Corrigendum: Stem Cell Therapy in Dengue Virus-Infected BALB/C Mice Improves Hepatic Injury

Sakinah S, Priya SP, Mok PL, Munisvaradass R, Teh SW, Sun Z, et al.

Front Cell Dev Biol, 2021;9:800659.
PMID: 35178398 DOI: 10.3389/fcell.2021.800659

[This corrects the article DOI: 10.3389/fcell.2021.637270.].
Fulltext Modulatory and regenerative potential of transplanted bone marrow-derived mesenchymal stem cells on rifampicin-induced kidney toxicity

Danjuma L, Mok PL, Higuchi A, Hamat RA, Teh SW, Koh AE, et al.

Regen Ther, 2018 Dec;9:100-110.
PMID: 30525080 DOI: 10.1016/j.reth.2018.09.001

INTRODUCTION: Anti-tuberculosis agent rifampicin is extensively used for its effectiveness. Possible complications of tuberculosis and prolonged rifampicin treatment include kidney damage; these conditions can lead to reduced efficiency of the affected kidney and consequently to other diseases. Bone marrow-derived mesenchymal stem cells (BMMSCs) can be used in conjunction with rifampicin to avert kidney damage; because of its regenerative and differentiating potentials into kidney cells. This research was designed to assess the modulatory and regenerative potentials of MSCs in averting kidney damage due to rifampicin-induced kidney toxicity in Wistar rats and their progenies. BMMSCs used in this research were characterized according to the guidelines of International Society for Cellular Therapy.
METHODS: The rats (male and female) were divided into three experimental groups, as follows: Group 1: control rats (4 males & 4 females); Group 2: rats treated with rifampicin only (4 males & 4 females); and Group 3: rats treated with rifampicin plus MSCs (4 males & 4 females). Therapeutic doses of rifampicin (9 mg/kg/day for 3-months) and MSCs infusions (twice/month for 3-months) were administered orally and intravenously respectively. At the end of the three months, the animals were bred together to determine if the effects would carry over to the next generation. Following breeding, the rats were sacrificed to harvest serum for biochemical analysis and the kidneys were also harvested for histological analysis and quantification of the glomeruli size, for the adult rats and their progenies.
RESULTS: The results showed some level of alterations in the biochemical indicators and histopathological damage in the rats that received rifampicin treatment alone, while the control and stem cells treated group showed apparently normal to nearly normal levels of both bio-indicators and normal histological architecture.
CONCLUSIONS: Intravenous administration of MSCs yielded sensible development, as seen from biochemical indicators, histology and the quantitative cell analysis, hence implying the modulatory and regenerative properties of MSCs.
Dental pulp stem cells therapy overcome photoreceptor cell death and protects the retina in a rat model of sodium iodate-induced retinal degeneration

Alsaeedi HA, Koh AE, Lam C, Rashid MBA, Harun MHN, Saleh MFBM, et al.

J. Photochem. Photobiol. B, Biol., 2019 Sep;198:111561.
PMID: 31352000 DOI: 10.1016/j.jphotobiol.2019.111561

Blindness and vision loss contribute to irreversible retinal degeneration, and cellular therapy for retinal cell replacement has the potential to treat individuals who have lost light sensitive photoreceptors in the retina. Retinal cells are well characterized in function, and are a subject of interest in cellular replacement therapy of photoreceptors and the retinal pigment epithelium. However, retinal cell transplantation is limited by various factors, including the choice of potential stem cell source that can show variability in plasticity as well as host tissue integration. Dental pulp is one such source that contains an abundance of stem cells. In this study we used dental pulp-derived mesenchymal stem cells (DPSCs) to mitigate sodium iodate (NaIO3) insult in a rat model of retinal degeneration. Sprague-Dawley rats were first given an intravitreal injection of 3 × 105 DPSCs as well as a single systemic administration of NaIO3 (40 mg/kg). Electroretinography (ERG) was performed for the next two months and was followed-up by histological analysis. The ERG recordings showed protection of DPSC-treated retinas within 4 weeks, which was statistically significant (* P ≤ .05) compared to the control. Retinal thickness of the control was also found to be thinner (*** P ≤ .001). The DPSCs were found integrated in the photoreceptor layer through immunohistochemical staining. Our findings showed that DPSCs have the potential to moderate retinal degeneration. In conclusion, DPSCs are a potential source of stem cells in the field of eye stem cell therapy due to its protective effects against retinal degeneration.

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