Displaying publications 21 - 28 of 28 in total

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  1. Yong KW, Safwani WKZW, Xu F, Zhang X, Choi JR, Abas WABW, et al.
    J Tissue Eng Regen Med, 2017 08;11(8):2217-2226.
    PMID: 26756982 DOI: 10.1002/term.2120
    Cryopreservation represents an efficient way to preserve human mesenchymal stem cells (hMSCs) at early culture/passage, and allows pooling of cells to achieve sufficient cells required for off-the-shelf use in clinical applications, e.g. cell-based therapies and regenerative medicine. To fully apply cryopreserved hMSCs in a clinical setting, it is necessary to evaluate their biosafety, e.g. chromosomal abnormality and tumourigenic potential. To date, many studies have demonstrated that cryopreserved hMSCs display no chromosomal abnormalities. However, the tumourigenic potential of cryopreserved hMSCs has not yet been evaluated. In the present study, we cryopreserved human adipose-derived mesenchymal stem cells (hASCs) for 3 months, using a slow freezing method with various cryoprotective agents (CPAs), followed by assessment of the tumourigenic potential of the cryopreserved hASCs after thawing and subculture. We found that long-term cryopreserved hASCs maintained normal levels of the tumour suppressor markers p53, p21, p16 and pRb, hTERT, telomerase activity and telomere length. Further, we did not observe significant DNA damage or signs of p53 mutation in cryopreserved hASCs. Our findings suggest that long-term cryopreserved hASCs are at low risk of tumourigenesis. These findings aid in establishing the biosafety profile of cryopreserved hASCs, and thus establishing low hazardous risk perception with the use of long-term cryopreserved hASCs for future clinical applications. Copyright © 2016 John Wiley & Sons, Ltd.
  2. Yong KW, Pingguan-Murphy B, Xu F, Abas WA, Choi JR, Omar SZ, et al.
    Sci Rep, 2015;5:9596.
    PMID: 25872464 DOI: 10.1038/srep09596
    Cryopreservation represents an effective technique to maintain the functional properties of human adipose-derived stem cells (ASCs) and allows pooling of cells via long-term storage for clinical applications, e.g., cell-based therapies. It is crucial to reduce freezing injury during the cryopreservation process by loading the ASCs with the optimum concentration of suitable cryoprotective agents (CPAs). In this study, human ASCs were preserved for 3 months in different combinations of CPAs, including 1) 0.25 M trehalose; 2) 5% dimethylsulfoxide (DMSO); 3) 10% DMSO; 4) 5% DMSO + 20% fetal bovine serum (FBS); 5) 10% DMSO + 20% FBS; 6) 10% DMSO + 90% FBS. Interestingly, even with a reduction of DMSO to 5% and without FBS, cryopreserved ASCs maintained high cell viability comparable with standard cryomedium (10% DMSO + 90% FBS), with normal cell phenotype and proliferation rate. Cryopreserved ASCs also maintained their differentiation capability (e.g., to adipocytes, osteocytes and chondrocytes) and showed an enhanced expression level of stemness markers (e.g., NANOG, OCT-4, SOX-2 and REX-1). Our findings suggest that 5% DMSO without FBS may be an ideal CPA for an efficient long-term cryopreservation of human ASCs. These results aid in establishing standardized xeno-free long-term cryopreservation of human ASCs for clinical applications.
  3. Choi JR, Pingguan-Murphy B, Wan Abas WA, Yong KW, Poon CT, Noor Azmi MA, et al.
    PLoS ONE, 2015;10(1):e0115034.
    PMID: 25615717 DOI: 10.1371/journal.pone.0115034
    Adipose tissue-derived stromal cells (ASCs) natively reside in a relatively low-oxygen tension (i.e., hypoxic) microenvironment in human body. Low oxygen tension (i.e., in situ normoxia), has been known to enhance the growth and survival rate of ASCs, which, however, may lead to the risk of tumourigenesis. Here, we investigated the tumourigenic potential of ASCs under their physiological condition to ensure their safe use in regenerative therapy. Human ASCs isolated from subcutaneous fat were cultured in atmospheric O2 concentration (21% O2) or in situ normoxia (2% O2). We found that ASCs retained their surface markers, tri-lineage differentiation potential, and self-renewal properties under in situ normoxia without altering their morphology. In situ normoxia displayed a higher proliferation and viability of ASCs with less DNA damage as compared to atmospheric O2 concentration. Moreover, low oxygen tension significantly up-regulated VEGF and bFGF mRNA expression and protein secretion while reducing the expression level of tumour suppressor genes p16, p21, p53, and pRb. However, there were no significant differences in ASCs telomere length and their relative telomerase activity when cultured at different oxygen concentrations. Collectively, even with high proliferation and survival rate, ASCs have a low tendency of developing tumour under in situ normoxia. These results suggest 2% O2 as an ideal culture condition for expanding ASCs efficiently while maintaining their characteristics.
  4. Yong KW, Li Y, Liu F, Bin Gao, Lu TJ, Wan Abas WA, et al.
    Sci Rep, 2016 10 05;6:33067.
    PMID: 27703175 DOI: 10.1038/srep33067
    Human mesenchymal stem cells (hMSCs) hold great promise in cardiac fibrosis therapy, due to their potential ability of inhibiting cardiac myofibroblast differentiation (a hallmark of cardiac fibrosis). However, the mechanism involved in their effects remains elusive. To explore this, it is necessary to develop an in vitro cardiac fibrosis model that incorporates pore size and native tissue-mimicking matrix stiffness, which may regulate cardiac myofibroblast differentiation. In the present study, collagen coated polyacrylamide hydrogel substrates were fabricated, in which the pore size was adjusted without altering the matrix stiffness. Stiffness is shown to regulate cardiac myofibroblast differentiation independently of pore size. Substrate at a stiffness of 30 kPa, which mimics the stiffness of native fibrotic cardiac tissue, was found to induce cardiac myofibroblast differentiation to create in vitro cardiac fibrosis model. Conditioned medium of hMSCs was applied to the model to determine its role and inhibitory mechanism on cardiac myofibroblast differentiation. It was found that hMSCs secrete hepatocyte growth factor (HGF) to inhibit cardiac myofibroblast differentiation via downregulation of angiotensin II type 1 receptor (AT1R) and upregulation of Smad7. These findings would aid in establishment of the therapeutic use of hMSCs in cardiac fibrosis therapy in future.
  5. Wong JJ, Phan HP, Phumeetham S, Ong JSM, Chor YK, Qian S, et al.
    Crit. Care Med., 2017 Jul 26.
    PMID: 28749854 DOI: 10.1097/CCM.0000000000002623
    OBJECTIVES: The Pediatric Acute Lung Injury Consensus Conference developed a pediatric specific definition for acute respiratory distress syndrome (PARDS). In this definition, severity of lung disease is stratified into mild, moderate, and severe groups. We aim to describe the epidemiology of patients with PARDS across Asia and evaluate whether the Pediatric Acute Lung Injury Consensus Conference risk stratification accurately predicts outcome in PARDS.

    DESIGN: A multicenter, retrospective, descriptive cohort study.

    SETTING: Ten multidisciplinary PICUs in Asia.

    PATIENTS: All mechanically ventilated children meeting the Pediatric Acute Lung Injury Consensus Conference criteria for PARDS between 2009 and 2015.

    INTERVENTIONS: None.

    MEASUREMENTS AND MAIN RESULTS: Data on epidemiology, ventilation, adjunct therapies, and clinical outcomes were collected. Patients were followed for 100 days post diagnosis of PARDS. A total of 373 patients were included. There were 89 (23.9%), 149 (39.9%), and 135 (36.2%) patients with mild, moderate, and severe PARDS, respectively. The most common risk factor for PARDS was pneumonia/lower respiratory tract infection (309 [82.8%]). Higher category of severity of PARDS was associated with lower ventilator-free days (22 [17-25], 16 [0-23], 6 [0-19]; p < 0.001 for mild, moderate, and severe, respectively) and PICU free days (19 [11-24], 15 [0-22], 5 [0-20]; p < 0.001 for mild, moderate, and severe, respectively). Overall PICU mortality for PARDS was 113 of 373 (30.3%), and 100-day mortality was 126 of 317 (39.7%). After adjusting for site, presence of comorbidities and severity of illness in the multivariate Cox proportional hazard regression model, patients with moderate (hazard ratio, 1.88 [95% CI, 1.03-3.45]; p = 0.039) and severe PARDS (hazard ratio, 3.18 [95% CI, 1.68, 6.02]; p < 0.001) had higher risk of mortality compared with those with mild PARDS.

    CONCLUSIONS: Mortality from PARDS is high in Asia. The Pediatric Acute Lung Injury Consensus Conference definition of PARDS is a useful tool for risk stratification.

  6. Hilpert P, Randall AK, Sorokowski P, Atkins DC, Sorokowska A, Ahmadi K, et al.
    Front Psychol, 2016;7:1404.
    PMID: 27698648
    [This corrects the article on p. 1106 in vol. 7, PMID: 27551269.].
  7. Hilpert P, Randall AK, Sorokowski P, Atkins DC, Sorokowska A, Ahmadi K, et al.
    Front Psychol, 2016;7:1106.
    PMID: 27551269 DOI: 10.3389/fpsyg.2016.01106
    OBJECTIVE: Theories about how couples help each other to cope with stress, such as the systemic transactional model of dyadic coping, suggest that the cultural context in which couples live influences how their coping behavior affects their relationship satisfaction. In contrast to the theoretical assumptions, a recent meta-analysis provides evidence that neither culture, nor gender, influences the association between dyadic coping and relationship satisfaction, at least based on their samples of couples living in North America and West Europe. Thus, it is an open questions whether the theoretical assumptions of cultural influences are false or whether cultural influences on couple behavior just occur in cultures outside of the Western world.

    METHOD: In order to examine the cultural influence, using a sample of married individuals (N = 7973) from 35 nations, we used multilevel modeling to test whether the positive association between dyadic coping and relationship satisfaction varies across nations and whether gender might moderate the association.

    RESULTS: RESULTS reveal that the association between dyadic coping and relationship satisfaction varies between nations. In addition, results show that in some nations the association is higher for men and in other nations it is higher for women.

    CONCLUSIONS: Cultural and gender differences across the globe influence how couples' coping behavior affects relationship outcomes. This crucial finding indicates that couple relationship education programs and interventions need to be culturally adapted, as skill trainings such as dyadic coping lead to differential effects on relationship satisfaction based on the culture in which couples live.

  8. Klionsky DJ, Abdelmohsen K, Abe A, Abedin MJ, Abeliovich H, Acevedo Arozena A, et al.
    Autophagy, 2016;12(1):1-222.
    PMID: 26799652 DOI: 10.1080/15548627.2015.1100356
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