Contributor: Dr Mahfuz Chowdhury
Assessment of morphological features of human Embryonic stem or induced Pluripotent Stem Cells (hESC/hiPSC) from brightfield/phase contrast images is a critical, non-invasive and low-cost quality procedure that stem cell researchers routinely use.
Because of various factors e.g., different batches of reagents, operator variability, acquisition of genomic changes by the cells during the culture period, and non-consistent cell culture equipment performance, a stem cell line morphology can gradually change indicating a change in cell quality.
Morphological characteristics of hESC/hiPSC can be assessed in two levels: colony level and single-cell level refs. [1] and [2].
hESC/hiPSC colony level
This assessment provides a quick assessment of the whole stem cell culture, therefore it is used more routinely than single-cell level.
The morphological features that are assessed at this level are:
Round and flat colony
Well-defined and smooth colony edge
cells in the colony are tightly packed
A comparison [ref. 3] of these features between good and bad colonies of a stem cell line (H9p35) is shown below.
hESC/hiPSC single cell level assessment
The morphological features that are assessed at this level are:
round and small cell
high nucleus: cytoplasm ratio i.e., nucleus occupies most of the cell region
prominent nucleoli/nucleolus
Single-cell morphological features and a schematic illustrating changes in these features, indicative of deviation from an undifferentiated state, are presented below.
Recently, machine-learning approaches is being developed for automated assessment of these morphological features [refs. 3, 4-5], but they are not still widely used.
References
[1] Wakui, Takashi et al. “Method for evaluation of human induced pluripotent stem cell quality using image analysis based on the biological morphology of cells.” Journal of medical imaging (Bellingham, Wash.) vol. 4,4 (2017): 044003. doi:10.1117/1.JMI.4.4.044003
[2] Orozco-Fuentes, Sirio et al. “Quantification of the morphological characteristics of hESC colonies.” Scientific reports vol. 9,1 17569. 26 Nov. 2019, doi:10.1038/s41598-019-53719-9
[3] Krasnova, Olga A et al. “Prognostic Analysis of Human Pluripotent Stem Cells Based on Their Morphological Portrait and Expression of Pluripotent Markers.” International journal of molecular sciences vol. 23,21 12902. 26 Oct. 2022, doi:10.3390/ijms232112902
[4] Yue, Guanghui et al. “Quality evaluation of induced pluripotent stem cell colonies by fusing multi-source features.” Computer methods and programs in biomedicine vol. 208 (2021): 106235. doi:10.1016/j.cmpb.2021.106235
[5] Piotrowski, Tobias et al. “Deep-learning-based multi-class segmentation for automated, non-invasive routine assessment of human pluripotent stem cell culture status.” Computers in biology and medicine vol. 129 (2021): 104172. doi:10.1016/j.compbiomed.2020.104172
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