10 Different Cell Morphology Assays & When to Use Them

1. Cell health assays

As the cell morphology is directly related to the physiological state and signaling state of a cell expressed by its phenotype, cell morphology can be used to evaluate cell health. In a cell health assay, a cell morphology parameter such as the solidity / roundness of a cell is evaluated and used to give information on the state of health of the cell and so is ideal for disease screening.

Analysis of the images and interpretation in cell health assays can be challenging without sufficient expertise, so automated image analysis software can be highly beneficial.

2. Endocytosis

Endocytosis is the process of the uptake of materials into the cell and so is an incredibly important part of drug evaluation. During the process of endocytosis, the cell morphology often distorts or changes as the uptake can be achieved by processes such as surrounding the external material with cell membrane that then forms a vesicle within the cell.

Endocytosis assays can be used to evaluate and identify uptake mechanisms of potential new therapeutics.

3. Phagocytosis

Phagocytosis is the process of ingestion or elimination of materials into the cell. The most common example is where phagocytes consume and eliminate other cellular species. As phagocytosis is a multistep process involving sensing, signaling and forming the new phagosome, there are distinct changes in the cell morphology. Phagocytosis assays are widely used in immunology studies and the development of therapeutics that target problematic cell populations.

4. Cell adherence

Cell adherence is one of the changes in cell morphology that can be an indicator of disease such as cancer and arthritis and lead to cellular functioning disruptions. Since cell adhesion receptors are connected to signal-transduction pathways, such cell–cell and cell–matrix interactions modulate cell phenotype, survival, differentiation, and migration. As a consequence, alterations in cell adhesion directly contribute to tumorigenesis and metastasis. Dynamic changes in cell adhesion allow stationary cells to become migratory and mediate morphogenesis in the proper spatio-temporal manner.  Many pathogens also use cell adherence to drive infection. Therefore, cell adherence assays can be a useful tool for disease studies.

5. Apoptosis

Apoptosis is a type of programmed cell death, and disruption to this process can lead to cancerous tumors. Changes in cell morphology are an important way of studying apoptosis as many of the steps induce changes in the cell shape and morphology. Checking for cell death in assays is important for drug discovery and many other applications.

6. Subcellular features detection & quantifications

Understanding the sub-cellular structures and counting the numbers of features is a very important part of cell morphology. Here we look at some more specific assays of certain sub-cellular features and their applications.

7. Nuclei

The nuclei is an important part in cell morphology assays as the genetic information contained in the nuclei is very important for characterizing and identifying cells. Changes in the cell morphology at the nuclei is a common disease marker. Moreover, morphological alterations of the nucleus have been found to serve as a deep learning predictor of senescence that is applicable across tissues and species and is associated with health outcomes in humans2. It is very important to check that therapeutics do not cause any unwanted changes in the cell morphology here as this could lead to disruption of cell function.

8. Mitochondria

Mitochondrial assays are another way of checking cell health as morphological changes in the mitochondria structure are often related to changes in the rates of other cellular processes such as apoptosis,embryonic development, metabolism and autophagy . Mitochondrial morphology encompasses a vast spectrum from small spheres/ovals and short tubules to elongated tubules and reticular networks, depending on cell types in varied tissues and organs. Among many types of mitochondrial shape changes, fission and fusion are the most defined and studied processes.

9. Golgi

The mammalian Golgi apparatus is a highly dynamic organelle, which is normally localized in the juxtanuclear space and plays an essential role in the regulation of cellular homeostasis. Golgi are typically very dynamic organelles but changes in the cell morphology in this region can indicate disease damage such as alcoholic liver damage, viral infection, cancer, different neurological diseases and ischemic stress. Assays of the Golgi morphology can thus be used for both investigation of disease biomarkers or progression mechanisms.

10. Microtubules

Microtubules (MTs) are highly dynamic polymers essential for a wide range of cellular physiologies, such as acting as directional railways for intracellular transport and position, guiding chromosome segregation during cell division, and controlling cell polarity and morphogenesis. Microtubules are involved in different functions including the assembly of mitotic spindle, in dividing cells, or axon extension, in neurons.  Microtubule organization was found to be essential for maintaining cellular morphology and function3 and hence changes in the shape and morphology of microtubules can provide information on the cell status and viability.

References

1.  Brancato, V., Oliveira, J. M., Correlo, V. M., Reis, R. L., & Kundu, S. C. (2020). Could 3D models of cancer enhance drug screening? Biomaterials, 232, 119744. https://doi.org/10.1016/j.biomaterials.2019.119744
2. Heckenbach, I., Mkrtchyan, G.V., Ezra, M.B. et al. Nuclear morphology is a deep learning biomarker of cellular senescence. Nat Aging 2, 742–755 (2022). https://doi.org/10.1038/s43587-022-00263-3
3. Lijiang Huang, Yan Peng, Xuetao Tao, Xiaoxiao Ding, Rui Li, Yongsheng Jiang, Wei Zuo, “Microtubule Organization Is Essential for Maintaining Cellular Morphology and Function”, Oxidative Medicine and Cellular Longevity, vol. 2022, Article ID 1623181, 15 pages, 2022. https://doi.org/10.1155/2022/1623181