On the cell surface, there are some circle-like bubbles.
Is this contamination?
I want to know about that.
Thank you.
Hello Roh Ji Hun,
It is not contamination. The circle- like bubbles that you observe are cells. It is a sign that the cells are undergoing mitosis. In adherent cells, this process begins in early prophase when cells decrease substrate adhesion and round up to assume a characteristic spherical shape. This process of cell rounding in early mitosis is a feature in animal cell division which is observed in cells in 2D and 3D culture. By creating a spherical cell shape at metaphase, mitotic rounding ensures that there is sufficient space within the cell to form mitotic spindle.
Best.
When observing cells in culture, any unexpected structures or changes in appearance warrant careful consideration. Circle-like bubbles on the cell surface could be indicative of several things, and it is important to approach the hypothesis of contamination with a structured rationale:
Possible Explanations
1. Microvesicles or Exosomes: Cells often release small vesicles as part of their normal physiological processes. These vesicles can appear as bubble-like structures on or surrounding the cells.
2. Cell Blebbing: This is a process where the cell membrane temporarily protrudes outward, forming bubble-like extensions. It is a normal occurrence during certain cellular activities like apoptosis (programmed cell death) but can sometimes be a response to stress.
3. Gas Bubbles: During incubation, CO2 bubbles can sometimes form if the culture plates are agitated or if the medium is not properly equilibrated to the incubator's environment.
4. Artefact of Staining or Imaging: Bubbles or circles may be an artefact from the process of staining, fixing, or imaging the cells.
5. Contaminants: The presence of bacterial, fungal, or yeast contamination can introduce structures that may resemble bubbles. Contamination can drastically affect cell health and the validity of experimental results.
Steps to Confirm Contamination
To determine if the cells are contaminated:
1. Visual Inspection: Under a microscope, look for signs such as:
- Clumping or irregular growth patterns.
- Changes in the turbidity or color of the medium.
- Presence of moving particles or structures that are distinct from cells.
2. Compare with Control: Always have an uncontaminated control culture to compare cell morphology and growth characteristics.
3. Fungus or Bacteria Tests: Use selective media or Gram staining to test for the presence of bacteria or fungi if contamination is suspected.
4. Re-evaluate Culture Conditions:
- Ensure CO2 and temperature settings correspond with the cell culture requirements.
- Confirm that the culture medium is fresh and was filtered correctly before use.
5. Mycoplasma Test: Perform a test for mycoplasma contamination, which is a common and often undetected source of cell culture contamination.
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