Neeladrisingha Das

All Publications

• Increased [18F]FDG uptake of radiation-induced giant cells: a single-cell study in lung cancer models. Npj imaging Das, N., Nguyen, H. T., Lu, W. J., Natarajan, A., Khan, S., Pratx, G. 2024; 2 (1): 14

  Abstract

  Positron emission tomography (PET), a cornerstone in cancer diagnosis and treatment monitoring, relies on the enhanced uptake of fluorodeoxyglucose ([18F]FDG) by cancer cells to highlight tumors and other malignancies. While instrumental in the clinical setting, the accuracy of [18F]FDG-PET is susceptible to metabolic changes introduced by radiation therapy. Specifically, radiation induces the formation of giant cells, whose metabolic characteristics and [18F]FDG uptake patterns are not fully understood. Through a novel single-cell gamma counting methodology, we characterized the [18F]FDG uptake of giant A549 and H1299 lung cancer cells that were induced by radiation, and found it to be considerably higher than that of their non-giant counterparts. This observation was further validated in tumor-bearing mice, which similarly demonstrated increased [18F]FDG uptake in radiation-induced giant cells. These findings underscore the metabolic implications of radiation-induced giant cells, as their enhanced [18F]FDG uptake could potentially obfuscate the interpretation of [18F]FDG-PET scans in patients who have recently undergone radiation therapy.

  View details for DOI 10.1038/s44303-024-00017-3

  View details for PubMedID 38912527

  View details for PubMedCentralID PMC11186760

• Ultrasensitive and multiplexed tracking of single cells using whole-body PET/CT. Science advances Nguyen, H. T., Das, N., Ricks, M., Zhong, X., Takematsu, E., Wang, Y., Ruvalcaba, C., Mehadji, B., Roncali, E., Chan, C. K., Pratx, G. 2024; 10 (24): eadk5747

  Abstract

  In vivo molecular imaging tools are crucially important for elucidating how cells move through complex biological systems; however, achieving single-cell sensitivity over the entire body remains challenging. Here, we report a highly sensitive and multiplexed approach for tracking upward of 20 single cells simultaneously in the same subject using positron emission tomography (PET). The method relies on a statistical tracking algorithm (PEPT-EM) to achieve a sensitivity of 4 becquerel per cell and a streamlined workflow to reliably label single cells with over 50 becquerel per cell of 18F-fluorodeoxyglucose (FDG). To demonstrate the potential of the method, we tracked the fate of more than 70 melanoma cells after intracardiac injection and found they primarily arrested in the small capillaries of the pulmonary, musculoskeletal, and digestive organ systems. This study bolsters the evolving potential of PET in offering unmatched insights into the earliest phases of cell trafficking in physiological and pathological processes and in cell-based therapies.

  View details for DOI 10.1126/sciadv.adk5747

  View details for PubMedID 38875333

  View details for PubMedCentralID PMC11177933

• Increased [18F]FDG uptake of radiation-induced giant cells: a single-cell study in lung cancer models npj Imaging Das, N., Nguyen, H. T., Lu, W., Natarajan, A., Khan, S., Pratx, G. 2024; 2: 1-10

  View details for DOI 10.1038/s44303-024-00017-3

• Efficient and multiplexed tracking of single cells using whole-body PET/CT. bioRxiv : the preprint server for biology Nguyen, H. T., Das, N., Wang, Y., Ruvalcaba, C., Mehadji, B., Roncali, E., Chan, C. K., Pratx, G. 2023

  Abstract

  In vivo molecular imaging tools are crucially important for elucidating how cells move through complex biological systems, however, achieving single-cell sensitivity over the entire body remains challenging. Here, we report a highly sensitive and multiplexed approach for tracking upwards of 20 single cells simultaneously in the same subject using positron emission tomography (PET). The method relies on a new tracking algorithm (PEPT-EM) to push the cellular detection threshold to below 4 Bq/cell, and a streamlined workflow to reliably label single cells with over 50 Bq/cell of 18F-fluorodeoxyglucose (FDG). To demonstrate the potential of method, we tracked the fate of over 70 melanoma cells after intracardiac injection and found they primarily arrested in the small capillaries of the pulmonary, musculoskeletal, and digestive organ systems. This study bolsters the evolving potential of PET in offering unmatched insights into the earliest phases of cell trafficking in physiological and pathological processes and in cell-based therapies.

  View details for DOI 10.1101/2023.08.23.554536

  View details for PubMedID 37662335

  View details for PubMedCentralID PMC10473747

• Preclinical evaluation of 89Zr-Panitumumab for biology-guided radiotherapy. International journal of radiation oncology, biology, physics Natarajan, A., Khan, S., Liang, X., Nguyen, H., Das, N., Anders, D., Malik, N., Oderinde, O. M., Chin, F., Rosenthal, E., Pratx, G. 2023

  Abstract

  Biology-guided radiotherapy (BgRT) uses real-time line-of-response data from on-board PET detectors to guide beamlet delivery during therapeutic radiation. The current workflow requires 18F-fluorodeoxyglucose (FDG) administration daily prior to each treatment fraction. However, there are advantages to reducing the number of tracer injections by using a PET tracer with a longer decay time. In this context, we investigated 89Zr-Panitumumab (89Zr-Pan), an antibody PET tracer with a half-life of 78 hours that can be imaged for up to 9 days using PET.The BgRT workflow was evaluated pre-clinically in mouse colorectal cancer xenografts (HCT116) using small-animal PET/CT for imaging, and image-guided kilovoltage conformal irradiation for therapy. Mice (n=5 per group) received 7 MBq of 89Zr-Pan as a single dose 2 weeks after tumor induction, with or without fractionated radiation therapy (RT; 6×6.6 Gy) to the tumor region. The mice were imaged longitudinally to assess the kinetics of the tracer over 9 days. PET images were then analyzed to determine the stability of the PET signal in irradiated tumors over time.Mice in the treatment group experienced complete tumor regression, whereas those in the control group were sacrificed due to tumor burden. PET imaging of 89Zr-Pan showed well-delineated tumors with minimal background in both groups. On day 9 post-injection, tumor uptake of 89Zr-Pan was 7.2 ± 1.7 in the control group vs 5.2 ± 0.5 in the treatment group (mean %ID/g ± SD; P = 0.07), both significantly higher than FDG uptake (1.1 ± 0.5 %ID/g) 1 hour post injection. To assess BgRT feasibility, the clinical eligibility criteria was computed using human-equivalent uptake values that were extrapolated from preclinical PET data. Based on this semiquantitative analysis, BgRT may be feasible for 5 consecutive days following a single 740 MBq injection of 89Zr-Pan.This study indicates the potential of long-lived antibody-based PET tracers for guiding clinical BgRT.

  View details for DOI 10.1016/j.ijrobp.2023.01.007

  View details for PubMedID 36669541

• Real-time optical oximetry during FLASH radiotherapy using a phosphorescent nanoprobe. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Ha, B., Liang, K., Liu, C., Melemenidis, S., Manjappa, R., Viswanathan, V., Das, N., Ashraf, R., Lau, B., Soto, L., Graves, E. E., Rao, J., Loo, B. W., Pratx, G. 2022

  Abstract

  The rapid depletion of oxygen during irradiation at ultra-high dose rate calls for tissue oximeters capable of high temporal resolution. This study demonstrates a water-soluble phosphorescent nanoprobe and fiber-coupled instrument, which together are used to measure the kinetics of oxygen depletion at 200 Hz during irradiation of in vitro solutions.

  View details for DOI 10.1016/j.radonc.2022.08.011

  View details for PubMedID 35964762