OSN-K 2024 - No 04 - Biselmol

Summary

This video script delves into the concept of mammalian cell culture, focusing on the differences between 2D and 3D cultures. It explains how mammalian cells, such as epithelial cells, muscle cells, and blood cells, are cultured for biomedical research, with an emphasis on how the growth environment affects cell behavior. The script also discusses the biological principles behind pH changes in culture media, the rapid division of cancer cells, and how altered gene expression in cancer cells influences their metabolism. Ultimately, it provides a comprehensive analysis of the role of cell culture in studying biological processes and diseases like cancer.

Takeaways

• 😀 Mammalian cell culture involves the proliferation of cells taken from mammalian tissue for biomedical testing outside the organism (in vitro).
• 😀 2D cell culture refers to the growth of cells in a flat, planar surface, while 3D culture better mimics the natural tissue environment and is essential for studying connective tissues.
• 😀 The culture medium plays a crucial role in cell growth, and its composition (including pH indicators like phenol red) affects cell behavior and the ability to monitor changes.
• 😀 The pH of the culture medium is an important factor. It can be indicated by the color change of phenol red, which shifts from red to yellow at lower pH (indicating acidic conditions).
• 😀 Cells from cancerous tissues (such as ovarian cancer) exhibit rapid and uncontrolled proliferation, leading to an altered culture environment with more acidic pH due to fermentation.
• 😀 Cancer cells primarily use anaerobic glycolysis (fermentation) for ATP production instead of oxidative phosphorylation, contributing to the lower pH of their surrounding medium.
• 😀 3D cultures are essential for studying connective tissues like muscle and blood cells, as they interact with the extracellular matrix (ECM), which is absent in 2D cultures.
• 😀 The karyotype of cancer cells is often abnormal, with chromosomal duplications and rearrangements due to errors in DNA repair mechanisms, which are more common in rapidly dividing cells.
• 😀 The expression of pyruvate dehydrogenase, which is involved in oxidative metabolism, is lower in cancer cells because they rely more on anaerobic pathways for energy.
• 😀 The ability to observe and analyze chromosomal abnormalities in cancer cells is easier due to their disorganized and fragmented chromosomal structure, which contrasts with normal cells.
• 😀 In cell culture experiments, individual B’s ovarian cancer cells are observed to exhibit faster and more significant changes in pH (faster yellowing) compared to normal cells, highlighting the faster proliferation and metabolic changes in cancer cells.

Q & A

What is the purpose of mammalian cell culture techniques?

Mammalian cell culture techniques are used to propagate cells from animal tissues, such as human or mammalian tissues, for biomedical experiments in vitro (outside of a living organism). These techniques facilitate biomedical testing on a smaller scale.

What factors determine the optimal growth conditions in cell culture?

The optimal growth conditions in cell culture depend on various factors, including the type of tissue from which the cells are derived and the medium used for culture. The medium is usually adjusted to meet the needs of the cells and can contain various nutrients and indicators like phenol red to monitor pH levels.

What is the difference between 2D and 3D cell culture techniques?

2D cell culture involves growing cells in a single, flat layer on a surface, such as a bottle or plate. This method is often used for epithelial cells. In contrast, 3D cell culture involves growing cells in a volume that allows for cell aggregation and interaction, mimicking the actual environment of tissues in a living organism, and is typically used for more complex tissues like connective tissue.

Why is 3D cell culture more representative of in vivo conditions than 2D culture?

3D cell culture is considered more representative of in vivo conditions because it allows cells to interact in three dimensions, forming aggregates and mimicking the extracellular matrix (ECM) interactions that are naturally present in living organisms, unlike the flat, planar arrangement seen in 2D culture.

Can blood and muscle cells be cultured using 2D techniques?

No, blood and muscle cells, which are part of connective tissue, require 3D cell culture for optimal growth. These cells are characterized by a large extracellular matrix (ECM) component, which can only be effectively recreated in 3D cultures.

What does the color change in the culture medium indicate?

The color change in the culture medium, due to the presence of phenol red, indicates changes in the pH. A lower pH causes the medium to turn yellow, while a higher pH causes the medium to turn red or even purple, depending on the pH level.

Why do cancerous cells, such as those from individual B, grow faster in culture?

Cancerous cells, like those from individual B, have rapid mitosis rates and an increased metabolic demand for ATP. These cells rely more on glycolysis (fermentation) rather than oxidative phosphorylation, producing lactic acid as a byproduct. The accumulation of lactic acid lowers the pH of the environment, accelerating cell growth and affecting the culture medium.

What is a karyotype, and how does it differ in cancerous cells?

A karyotype is the characteristic arrangement of chromosomes in a cell. In cancerous cells, such as those from individual B, the karyotype is abnormal, with irregular chromosome numbers, breaks, and duplications, due to uncontrolled DNA repair processes and rapid cell division.

How do cancer cells' chromosomes differ from normal cells?

Cancer cells often exhibit a fragmented and chaotic chromosomal structure, with abnormal numbers of chromosomes and DNA sequences. This is in contrast to normal cells, where chromosomes are organized in pairs and maintain a stable genetic structure.

Why is the expression of pyruvate dehydrogenase enzyme lower in cancer cells?

In cancer cells, such as those from individual B, the expression of pyruvate dehydrogenase (which facilitates the conversion of pyruvate into acetyl-CoA in oxidative phosphorylation) is lower because cancer cells preferentially use anaerobic glycolysis to generate ATP, bypassing the need for oxidative phosphorylation and the enzymes involved in it.