Education & Certifications

  • BS, University of California, Irvine, Biological Sciences (2016)


All Publications

  • Brain Iron Assessment after Ferumoxytol-enhanced MRI in Children and Young Adults with Arteriovenous Malformations: A Case-Control Study. Radiology Iv, M., Ng, N. N., Nair, S., Zhang, Y., Lavezo, J., Cheshier, S. H., Holdsworth, S. J., Moseley, M. E., Rosenberg, J., Grant, G. A., Yeom, K. W. 2020: 200378


    Background Iron oxide nanoparticles are an alternative contrast agent for MRI. Gadolinium deposition has raised safety concerns, but it is unknown whether ferumoxytol administration also deposits in the brain. Purpose To investigate whether there are signal intensity changes in the brain at multiecho gradient imaging following ferumoxytol exposure in children and young adults. Materials and Methods This retrospective case-control study included children and young adults, matched for age and sex, with brain arteriovenous malformations who received at least one dose of ferumoxytol from January 2014 to January 2018. In participants who underwent at least two brain MRI examinations (subgroup), the first and last available examinations were analyzed. Regions of interests were placed around deep gray structures on quantitative susceptibility mapping and R2* images. Mean susceptibility and R2* values of regions of interests were recorded. Measurements were assessed by linear regression analyses: a between-group comparison of ferumoxytol-exposed and unexposed participants and a within-group (subgroup) comparison before and after exposure. Results Seventeen participants (mean age standard deviation, 13 years 5; nine male) were in the ferumoxytol-exposed (case) group, 21 (mean age, 14 years 5; 11 male) were in the control group, and nine (mean age, 12 years 6; four male) were in the subgroup. The mean number of ferumoxytol administrations was 2 1 (range, one to four). Mean susceptibility (in parts per million [ppm]) and R2* (in inverse seconds [sec-1]) values of the dentate (case participants: 0.06 ppm 0.04 and 23.87 sec-1 4.13; control participants: 0.02 ppm 0.03 and 21.7 sec-1 5.26), substantia nigrae (case participants: 0.08 ppm 0.06 and 27.46 sec-1 5.58; control participants: 0.04 ppm 0.05 and 24.96 sec-1 5.3), globus pallidi (case participants: 0.14 ppm 0.05 and 30.75 sec-1 5.14; control participants: 0.08 ppm 0.07 and 28.82 sec-1 6.62), putamina (case participants: 0.03 ppm 0.02 and 20.63 sec-1 2.44; control participants: 0.02 ppm 0.02 and 19.65 sec-1 3.6), caudate (case participants: -0.1 ppm 0.04 and 18.21 sec-1 3.1; control participants: -0.06 ppm 0.05 and 18.83 sec-1 3.32), and thalami (case participants: 0 ppm 0.03 and 16.49 sec-1 3.6; control participants: 0.02 ppm 0.02 and 18.38 sec-1 2.09) did not differ between groups (susceptibility, P = .21; R2*, P = .24). For the subgroup, the mean interval between the first and last ferumoxytol administration was 14 months 8 (range, 1-25 months). Mean susceptibility and R2* values of the dentate (first MRI: 0.06 ppm 0.05 and 25.78 sec-1 5.9; last MRI: 0.06 ppm 0.02 and 25.55 sec-1 4.71), substantia nigrae (first MRI: 0.06 ppm 0.06 and 28.26 sec-1 9.56; last MRI: 0.07 ppm 0.06 and 25.65 sec-1 6.37), globus pallidi (first MRI: 0.13 ppm 0.07 and 27.53 sec-1 8.88; last MRI: 0.14 ppm 0.06 and 29.78 sec-1 6.54), putamina (first MRI: 0.03 ppm 0.03 and 19.78 sec-1 3.51; last MRI: 0.03 ppm 0.02 and 19.73 sec-1 3.01), caudate (first MRI: -0.09 ppm 0.05 and 21.38 sec-1 4.72; last MRI: -0.1 ppm 0.05 and 18.75 sec-1 2.68), and thalami (first MRI: 0.01 ppm 0.02 and 17.65 sec-1 5.16; last MRI: 0 ppm 0.02 and 15.32 sec-1 2.49) did not differ between the first and last MRI examinations (susceptibility, P = .95; R2*, P = .54). Conclusion No overall significant differences were found in susceptibility and R2* values of deep gray structures to suggest retained iron in the brain between ferumoxytol-exposed and unexposed children and young adults with arteriovenous malformations and in those exposed to ferumoxytol over time. RSNA, 2020.

    View details for DOI 10.1148/radiol.2020200378

    View details for PubMedID 32930651

  • Locoregional delivery of stem cell-based therapies. Science translational medicine Ng, N. N., Thakor, A. S. 2020; 12 (547)


    Interventional regenerative medicine (IRM) uses image-guided, minimally invasive procedures for the targeted delivery of stem cell-based therapies to regenerate, replace, or repair damaged organs. Although many cellular therapies have shown promise in the preclinical setting, clinical results have been suboptimal. Most intravenously delivered cells become trapped in the lungs and reticuloendothelial system, resulting in little therapy reaching target tissues. IRM aims to increase the efficacy of cell-based therapies by locoregional stem cell delivery via endovascular, endoluminal, or direct injection into tissues. This review highlights routes of delivery, disease states, and mechanisms of action involved in the targeted delivery of stem cells.

    View details for DOI 10.1126/scitranslmed.aba4564

    View details for PubMedID 32522806

  • Association of Pediatric Acute-Onset Neuropsychiatric Syndrome With Microstructural Differences in Brain Regions Detected via Diffusion-Weighted Magnetic Resonance Imaging. JAMA network open Zheng, J., Frankovich, J., McKenna, E. S., Rowe, N. C., MacEachern, S. J., Ng, N. N., Tam, L. T., Moon, P. K., Gao, J., Thienemann, M., Forkert, N. D., Yeom, K. W. 2020; 3 (5): e204063


    Epidemiological studies indicate a link between obsessive-compulsive disorder and infections, particularly streptococcal pharyngitis. Pediatric acute-onset neuropsychiatric syndrome (PANS) manifests suddenly with obsessions, compulsions, and other behavioral disturbances, often after an infectious trigger. The current working model suggests a unifying inflammatory process involving the central nervous system, particularly the basal ganglia.To investigate whether diffusion-weighted magnetic resonance imaging (DWI) detects microstructural abnormalities across the brain regions of children with PANS.Case-control study performed at a single-center, multidisciplinary clinic in the United States focusing on the evaluation and treatment of children with PANS. Sixty consecutive patients who underwent 3 Tesla (T) magnetic resonance imaging (MRI) before immunomodulation from September 3, 2012, to March 30, 2018, were retrospectively reviewed for study inclusion. Six patients were excluded by blinded investigators because of imaging or motion artifacts, 3 patients for major pathologies, and 17 patients for suboptimal atlas image registration. In total, 34 patients with PANS before initiation of treatment were compared with 64 pediatric control participants.Using atlas-based MRI analysis, regional brain volume, diffusion, and cerebral blood flow were measured in the cerebral white matter, cerebral cortex, thalamus, caudate, putamen, pallidum, hippocampus, amygdala, nucleus accumbens, and brainstem. An age and sex-controlled multivariable analysis of covariance was used to compare patients with control participants.This study compared 34 patients with PANS (median age, 154 months; age range, 55-251 months; 17 girls and 17 boys) and 64 pediatric control participants (median age, 139 months; age range, 48-213 months); 41 girls and 23 boys). Multivariable analysis demonstrated a statistically significant difference in MRI parameters between patients with PANS and control participants (F21,74?=?6.91; P?

    View details for DOI 10.1001/jamanetworkopen.2020.4063

    View details for PubMedID 32364596

  • Cerebral volume and diffusion MRI changes in children with sensorineural hearing loss. NeuroImage. Clinical Moon, P. K., Qian, J. Z., McKenna, E., Xi, K., Rowe, N. C., Ng, N. N., Zheng, J., Tam, L. T., MacEachern, S. J., Ahmad, I., Cheng, A. G., Forkert, N. D., Yeom, K. W. 2020; 27: 102328


    Sensorineural hearing loss (SNHL) is the most prevalent congenital sensory deficit in children. Information regarding underlying brain microstructure could offer insight into neural development in deaf children and potentially guide therapies that optimize language development. We sought to quantitatively evaluate MRI-based cerebral volume and gray matter microstructure children with SNHL.We conducted a retrospective study of children with SNHL who obtained brain MRI at 3T. The study cohort comprised 63 children with congenital SNHL without known focal brain lesion or structural abnormality (33 males; mean age 5.3years; age range 1 to 11.8years) and 64 age-matched controls without neurological, developmental, or MRI-based brain macrostructure abnormality. An atlas-based analysis was used to extract quantitative volume and median diffusivity (ADC) in the following brain regions: cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, brain stem, and cerebral white matter. SNHL patients were further stratified by severity scores and hearing loss etiology.Children with SNHL showed higher median ADC of the cortex (p=.019), thalamus (p<.001), caudate (p=.005), and brainstem (p=.003) and smaller brainstem volumes (p=.007) compared to controls. Patients with profound bilateral SNHL did not show any significant differences compared to patients with milder bilateral SNHL, but both cohorts independently had smaller brainstem volumes compared to controls. Children with unilateral SNHL showed greater amygdala volumes compared to controls (p=.021), but no differences were found comparing unilateral SNHL to bilateral SNHL. Based on etiology for SNHL, patients with Pendrin mutations showed higher ADC values in the brainstem (p=.029, respectively); patients with Connexin 26 showed higher ADC values in both the thalamus (p<.001) and brainstem (p<.001) compared to controls.SNHL patients showed significant differences in diffusion and volume in brain subregions, with region-specific findings for patients with Connexin 26 and Pendrin mutations. Future longitudinal studies could examine macro- and microstructure changes in children with SNHL over development and potential predictive role for MRI after interventions including cochlear implant outcome.

    View details for DOI 10.1016/j.nicl.2020.102328

    View details for PubMedID 32622314

  • Comparisons of dual isogenic human iPSC pairs identify functional alterations directly caused by an epilepsy associated SCN1A mutation Neurobiology of Disease Xie, Y., Ng, N. N., Safrina, O. S., Ramos, C. M., Ess, K. C., Schwartz, P. H., Smith, M. A., O'Dowd, D. K. 2020; 134: 104627
  • Emerging role of stem cell-derived extravesicular microRNAs in age-associated human diseases and in different therapies of longevity. Ageing Research Reviews Ullah, M., Ng, N. N., Concepcion, W., Thakor, A. S. 2020; 57: 100979


    Organismal aging involves the progressive decline in organ function and increased susceptibility to age-associated diseases. This has been associated with the aging of stem cell populations within the body that decreases the capacity of stem cells to self-renew, differentiate, and regenerate damaged tissues and organs. This review aims to explore how aging is associated with the dysregulation of stem cell-derived extracellular vesicles (SCEVs) and their corresponding miRNA cargo (SCEV-miRNAs), which are short non-coding RNAs involved in post-transcriptional regulation of target genes. Recent evidence has suggested that in aging stem cells, SCEV-miRNAs may play a vital role regulating various processes that contribute to aging: cellular senescence, stem cell exhaustion, telomere length, and circadian rhythm. Hence, further clarifying the age-dependent molecular mechanisms through which SCEV-miRNAs exert their downstream effects may inform a greater understanding of the biology of aging, elucidate their role in stem cell function, and identify important targets for future regenerative therapies. Additionally, current studies evaluating therapeutic role of SCEVs and SCEV-miRNAs in treating several age-associated diseases are also discussed.

    View details for DOI 10.1016/j.arr.2019.100979

  • Mesenchymal stem cells confer chemoresistance in breast cancer via a CD9 dependent mechanism. Oncotarget Ullah, M., Akbar, A., Ng, N. N., Concepcion, W., Thakor, A. S. 2019; 10 (37): 3435?50


    The development of chemotherapy drug resistance remains a significant barrier for effective therapy in several cancers including breast cancer. Bone marrow-derived mesenchymal stem cells (BMMSCs) have previously been shown to influence tumor progression and the development of chemoresistance. In the present study, we showed that when GFP labelled BMMSCs and RFP labelled HCC1806 cells are injected together in vivo, they create tumors which contain a new hybrid cell that has characteristics of both BMMSCs and HCC1806 cells. By labelling these cells prior to their injection, we were then able to isolate new hybrid cell from harvested tumors using FACS (DP-HCC1806:BMMSCs). Interestingly, when DP-HCC1806:BMMSCs were then injected into the mammary fat pad of NOD/SCID mice, they produced xenograft tumors which were smaller in size, and exhibited resistance to chemotherapy drugs (i.e. doxorubicin and 5-fluorouracil), when compared tumors from HCC1806 cells alone. This chemoresistance was shown to associated with an increased expression of tetraspanins (CD9, CD81) and drug resistance proteins (BCRP, MDR1). Subsequent siRNA-mediated knockdown of BMMSC-CD9 in DP-HCC1806:BMMSCs resulted in an attenuation of doxorubicin and 5-fluorouracil chemoresistance associated with decreased BCRP and serum cytokine expression (CCL5, CCR5, CXCR12). Our findings suggest that within the tumor microenvironment, CD9 is responsible for the crosstalk between BMMSCs and HCC1806 breast cancer cells (via CCL5, CCR5, and CXCR12) which contributes to chemoresistance. Hence, BMMSC-CD9 may serve as an important therapeutic target for the treatment of breast cancer.

    View details for DOI 10.18632/oncotarget.26952

    View details for PubMedID 31191817

    View details for PubMedCentralID PMC6544397

  • Reproducible and efficient generation of functionally active neurons from human iPSCs for preclinical disease modeling. Stem Cell Research *Xie, Y., *Schutte, R. J., *Ng, N. N., Ess, K. C., Schwartz, P. H., O'Dowd, D. K. 2018; 26: 84-94 (*authors contributed equally)
  • Astrocyte-enriched feeder layers from cryopreserved cells support differentiation of spontaneously active networks of human iPSC-derived neurons. Journal of Neuroscience Methods *Schutte, R. J., *Xie, Y., *Ng, N. N., Figueroa, P., Pham, A. T., O'Dowd, D. K. 2018; 294: 91-101 (*authors contributed equally)
  • Research Associates Program: Expanding clinical research productivity with undergraduate students. SAGE Open Medicine Hoonpongsimanont, W., Sahota, P. K., Ng, N. N., Farooqui, M. J., Chakravarthy, B., Patel, B., Lotfipour, S. 2017; 5: 1-7

    View details for DOI 10.1177/2050312117730245

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