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  1. Khoo TS, Hamidah Hussin N, Then SM, Jamal R
    Differentiation, 2013 Feb;85(3):110-8.
    PMID: 23722082 DOI: 10.1016/j.diff.2013.01.004
    Human embryonic stem cells (hESc) are known for its pluripotency and self renewal capability, thus possess great potential in regenerative medicine. However, the lack of suitable xenofree extracellular matrix substrate inhibits further applications or the use of hESc in cell-based therapy. In this study, we described a new differentiation method, which generates a homogeneous population of mesenchymal progenitor cells (hESc-MPC) from hESc via epithelial-mesenchymal transition. The extracellular matrix (ECM) proteins from hESc-MPC had in turn supported the undifferentiated expansion of hESc. Immunocytochemistry and flow cytometry characterization of hESc-MPC revealed the presence of early mesenchymal markers. Tandem mass spectometry analysis of ECM produced by hESc-MPC revealed the presence of a mixture of extracellular proteins which includes tenascin C, fibronectin, and vitronectin. The pluripotency of hESc (MEL-1) cultured on the ECM was maintained as shown by the expression of pluripotent genes (FoxD3, Oct-4, Tdgf1, Sox-2, Nanog, hTERT, Rex1), protein markers (SSEA-3, SSEA-4, TRA-1-81, TRA-1-60, Oct-4) and the ability to differentiate into cells representative of ectoderm, endoderm and mesoderm. In summary, we have established a xeno-free autogenic feeder free system to support undifferentiated expansion of hESc, which could be of clinical relevance.
  2. Huan NC, Mohamed Arifin N, Khoo TS, Lai YC
    Respirol Case Rep, 2020 Apr;8(3):e00544.
    PMID: 32128215 DOI: 10.1002/rcr2.544
    Subcutaneous emphysema (SE) is a common but usually self-limiting complication of cardiothoracic procedures. Rarely, it can be life threatening and is characterized by extensive cutaneous tension and airway compromise requiring immediate intervention. There is a paucity of data on the most efficacious treatment methods for extensive SE. We report an 80-year-old gentleman who developed massive SE necessitating intubation for airway protection following a right chest tube insertion for spontaneous secondary pneumothorax. His SE persisted despite adequate thoracic drainage via a new chest tube. It was then decided to insert two negative pressure wound therapy dressings (NPWTD) or vacuum dressings in the patient's subcutaneous tissue layer via incisions made at anterior chest wall. The dressings were removed after four days in view of significant improvements. NPWTD appears to be an effective, well-tolerated, safe, and inexpensive approach that hastens the resolution of SE without the need for invasive thoracic surgeries.
  3. Khoo TS, Jamal R, Abdul Ghani NA, Alauddin H, Hussin NH, Abdul Murad NA
    Stem Cell Rev Rep, 2020 04;16(2):251-261.
    PMID: 32016780 DOI: 10.1007/s12015-020-09956-x
    The discovery of induced pluripotent stem (iPS) cells in 2006 marked a major breakthrough in regenerative medicine, enabling reversal of terminally differentiated somatic cells into pluripotent stem cells. The embryonic stem (ES) cells-like pluripotency and unlimited self-renewal capability of iPS cells have granted them enormous potential in many applications, particularly regenerative therapy. Unlike ES cells, however, iPS cells exhibit somatic memories which were carried over from the tissue of origin thus limited its translation in clinical applications. This review provides an updated overview of the retention of various somatic memories associated with the cellular identity, age and metabolism of tissue of origin in iPS cells. The influence of cell types, stage of maturation, age and various other factors on the retention of somatic memory has been discussed. Recent evidence of somatic memory in the form of epigenetic, transcriptomic, metabolic signatures and its functional manifestations in both in vitro and in vivo settings also have been reviewed. The increasing number of studies which had adopted isogenic cell lines for comparisons in recent years had facilitated the identification of genuine somatic memories. These memories functionally affect iPS cells and its derivatives and are potentially tumorigenic thus, raising concerns on their safety in clinical application. Various approaches for memory erasure had since being reported and their efficacies were highlighted in this review.
  4. Lee SY, Ma J, Khoo TS, Abdullah N, Nik Md Noordin Kahar NNF, Abdul Hamid ZA, et al.
    Front Bioeng Biotechnol, 2021;9:735090.
    PMID: 34733829 DOI: 10.3389/fbioe.2021.735090
    Stem cell-based therapy appears as a promising strategy to induce regeneration of damaged and diseased tissues. However, low survival, poor engraftment and a lack of site-specificity are major drawbacks. Polysaccharide hydrogels can address these issues and offer several advantages as cell delivery vehicles. They have become very popular due to their unique properties such as high-water content, biocompatibility, biodegradability and flexibility. Polysaccharide polymers can be physically or chemically crosslinked to construct biomimetic hydrogels. Their resemblance to living tissues mimics the native three-dimensional extracellular matrix and supports stem cell survival, proliferation and differentiation. Given the intricate nature of communication between hydrogels and stem cells, understanding their interaction is crucial. Cells are incorporated with polysaccharide hydrogels using various microencapsulation techniques, allowing generation of more relevant models and further enhancement of stem cell therapies. This paper provides a comprehensive review of human stem cells and polysaccharide hydrogels most used in regenerative medicine. The recent and advanced stem cell microencapsulation techniques, which include extrusion, emulsion, lithography, microfluidics, superhydrophobic surfaces and bioprinting, are described. This review also discusses current progress in clinical translation of stem-cell encapsulated polysaccharide hydrogels for cell delivery and disease modeling (drug testing and discovery) with focuses on musculoskeletal, nervous, cardiac and cancerous tissues.
  5. Ramarmuty HY, Huan NC, Nyanti LE, Khoo TS, Renganathan T, Manoh AZ, et al.
    Ther Adv Respir Dis, 2024;18:17534666241231122.
    PMID: 38357899 DOI: 10.1177/17534666241231122
    Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is an established minimally invasive method for the diagnosis of benign and malignant conditions. Continuous efforts are underway to improve the material adequacy of EBUS-TBNA, including the introduction of a new technique called EBUS-guided transbronchial nodal cryobiopsy (EBUS-TBNC). This method allows for the retrieval of larger and well-preserved histologic samples from the mediastinum. We present a case series of four patients who underwent combined EBUS-TBNA and EBUS-TBNC procedures in our centre. All procedures were performed under general anaesthesia using a convex probe EBUS scope (Pentax EB-1970UK). Two patients were diagnosed with malignancy and two with benign disorders (silicosis and tuberculosis). In the malignant cases, both EBUS-TBNA/cell block and cryobiopsy provided a diagnosis but cryobiopsy yielded more material for ancillary tests in one patient. However, in the benign cases, there was discordance between EBUS-TBNA/cell block and cryobiopsy. Only cryobiopsy detected granuloma in the patient with TB (tuberculosis), and in the patient with silicosis, TBNC provided a better overall histological evaluation, leading to a definitive diagnosis. No complications were observed. This case series supports the potential diagnostic value of combining EBUS-TBNA and EBUS-TBNC, particularly in benign mediastinal lesions (granulomatous diseases), and in cases requiring additional molecular tests in cancer diagnosis.
  6. Soh JE, Abu N, Sagap I, Mazlan L, Yahaya A, Mustangin M, et al.
    Immunotherapy, 2019 10;11(14):1205-1219.
    PMID: 31478431 DOI: 10.2217/imt-2019-0073
    Colorectal cancer is the third commonest malignancy in Asia including Malaysia. The immunogenic cancer-testis antigens, which are expressed in a variety of cancers but with limited expression in normal tissues except the testis, represent an attractive approach to improve treatment options for colorectal cancer. We aimed to validate four PASD1 peptides as the immunotherapeutic targets in colorectal cancer. First, PASD1 mRNA and protein expression were determined via real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. The PASD1 peptides specific to HLA-A*24:02 were investigated using IFN-y-ELISpot assay, followed by the cytolytic and granzyme-B-ELISpot assays to analyze the cytolytic effects of CD8+ T cells. Gene and protein expressions of PASD1 were detected in 20% and 17.3% of colorectal cancer samples, respectively. PASD1(4) peptide was shown to be immunogenic in colorectal cancer samples. CD8+ T cells raised against PASD1(4) peptide were able to lyze HLA-A*24:02+ PASD1+ cells. Our results reveal that PASD1(4) peptide represents a potential target for colorectal cancer.
  7. Chia WC, Khoo TS, Abdul Wahid SFS, Razak NFA, Alauddin H, Raja Sabudin RZA, et al.
    Ann Hematol, 2019 May;98(5):1279-1291.
    PMID: 30783731 DOI: 10.1007/s00277-019-03626-w
    Short tandem repeat (STR) analysis is used in chimerism monitoring after allogeneic hematopoietic stem cell transplantation (HSCT) for patients with various hematologic malignancies. Commercial forensic STR kits often contain loci with huge differences in power of discrimination (PD) across populations, causing some loci to be less informative for chimerism analysis in certain populations. This study aimed to construct a new STR multiplex panel with highly informative loci for efficient chimerism analysis. Thirteen STR markers which exhibit high PD (> 0.9) in at least 80% of 50 populations globally were selected to form a new panel and used in STR analysis of 253 Malaysian subjects. Cumulative power of discrimination (CPD) and combined power of exclusion (CPE) were determined from 253 Malaysian individuals. Loci informativity was assessed and compared to the commercial AmpFLSTR Identifiler PCR Amplification kit in 14 donor-recipient pairs. The new panel had detected 202 unique alleles including five novel alleles from the 253 individuals with high CPD and CPE (> 0.99999999999999999 and > 0.999999997 respectively). All loci from the new panel in the donor-recipient pair analysis showed higher than 50% informativity, while five loci from the commercial kit demonstrated lower than 50% informativity. Four loci from the new panel ranked the highest informativity. A sequenced allelic ladder which consists of 202 unique alleles from the 253 subjects was also developed to ensure accurate allele designation. The new 13-loci STR panel, thus, could serve as an additional powerful, accurate, and highly informative panel for chimerism analysis for HSCT patients.
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