title: Original Research: Label-free detection for radiation-induced apoptosis in glioblastoma cells.
abstract: Current flow cytometry (FCM) requires fluorescent dyes labeling cells which make the procedure costly and time consuming. This manuscript reports a feasibility study of detecting the cell apoptosis with a label-free method in glioblastoma cells. A human glioma cell line M059K was exposed to 8 Gy dose of radiation, which enables the cells to undergo radiation-induced apoptosis. The rates of apoptosis were studied at different time points post-irradiation with two different methods: FCM in combination with Annexin V-FITC/PI staining and a newly developed technique named polarization diffraction imaging flow cytometry. Totally 1000 diffraction images were acquired for each sample and the gray level co-occurrence matrix (GLCM) algorithm was used in morphological characterization of the apoptotic cells. Among the feature parameters extracted from each image pair, we found that the two GLCM parameters of angular second moment (ASM) and sum entropy (SumEnt) exhibit high sensitivities and consistencies as the apoptotic rates (Pa) measured with FCM method. In addition, no significant difference exists between Pa and ASM_S, Pa and SumEnt_S, respectively (P > 0.05). These results demonstrated that the new label-free method can detect cell apoptosis effectively. Cells can be directly used in the subsequent biochemical experiments as the structure and function of cells and biomolecules are well-preserved with this new method.
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Qi
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Feng
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China Department of Radiation Oncology, Tianjin Medical University Cancer Institute & Hospital, Tianjin 300060, China.
authors.forename: Chengwen
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Changrong
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sa
authors.affiliation: Department of Biomedical Engineering, Tianjin University, Tianjin 300072, China Department of Radiation Oncology, Tianjin Medical University Cancer Institute & Hospital, Tianjin 300060, China Department of Radiation Oncology, East Carolina University, Greenville, NC 27834, USA sayu@tju.edu.cn.
authors.forename: Yuanming
authors.initials: Y
authors.lastname: Feng
mesh_terms: D017304:Annexin A5 / Q000627:therapeutic use; D017209:Apoptosis / Q000528:radiation effects*; D045744:Cell Line, Tumor; D004396:Coloring Agents / Q000627:therapeutic use; D005240:Feasibility Studies; D005434:Flow Cytometry / Q000379:methods; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000627:therapeutic use; D005909:Glioblastoma / Q000532:radiotherapy*; D006801:Humans; D013997:Time Factors
chemical_list: D017304:Annexin A5; D004396:Coloring Agents; C492760:FITC-annexin A5; D016650:Fluorescein-5-isothiocyanate
keywords: Glioblastoma cell; apoptosis; automatic feature extraction; cell morphology; flow cytometry; polarization diffraction imaging