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The Challenge of Stem Cell Culture

11/04/19

Does your lab come up against challenges with stem cell culture? Or would you like to know more about how this process could benefit your research? In this article we discuss what stem cells are, what they are used for and explore the unique challenges of the stem cell culture process.

A brief introduction to stem cells

Stem cells are starting point for every cell.  They are undifferentiated cells that have the ability to develop into different kinds of specific cells. For example, an individual stem cell could mature or ‘differentiate’ to become a muscle cell, an active cell in immune system or a structural cell in bone. The stem cell can differentiate down any of these lines to provide these functions depending on the conditions it is put under.

Stem cells have the unique ability to self-renew in the body; dividing themselves to create a new cell in response to certain triggers, that can then become a mature cell of a specialised type. Many types of stem cells are called ‘pluripotent’ meaning they can become almost any other kind of cell in the body, whereas others have more limited functions and are known as ‘multipotent’, ‘tissue-specific’ or ‘somatic’ stem cells.

Stem cells are usually classified into one of three categories:

  • Embryonic stem cells – pluripotent cells in human embryos that form the basis of the entire body.
  • Adult stem cells – more specialised cells found throughout the body used for ongoing renewal and maintenance but with a more limited set of potential specialisation abilities (i.e. multipotent)
  • Induced pluripotent stem (iPS) cells – laboratory-engineered stem cells created from reprogrammed cells of other types (such as skin or muscle tissue cells).

Due to their unique properties, stem cells are highly attractive prospects for research in human therapies, drug discovery, and investigations into various types of disease.

However, they are not always easy to culture successfully.

Why stem cells are difficult to culture

Stem cells present certain difficulties that can make them hard to culture for some applications. The culture medium needs to be biocompatible for successful culture  to take place, and this usually means coating the vessel with cells of a very similar type. However, because stem cells can self-renew indefinitely a ‘Feeder layer’ is required. A feeder layer is a layer of cells that has been treated to inhibit growth. It is required in order to provide nutrients to the target cells. Traditionally this feeder layer was made of mouse embryo cells. This in itself can cause issues as the feeder layer may pass viruses onto the cell culture. Modern techniques have limited this impact, but it is still an important safety consideration.

It is also difficult to initially generate an embryonic stem cell line and can require several attempts to affix target cells to the culture vessel.

A failure to adequately culture stem cells can lead to significant costs, delays and damage to reputations, as discussed in our infographic.

Successful stem cell culture

A successful stem cell line is capable of providing many sub-cultures (where some cells are transferred from an original culture vessel to grow in new vessels, multiplying the number of available samples) in a number of ‘passages.’ Many applications require that stem cells retain the ability to specialise when needed by maintaining their pluripotency. A successful culture process will ensure that stem cells do not lose this ability or differentiate before they are required to.

Through testing it should be established that the cell line development and culture conditions will not limit the stem cells from carrying out any subsequent differentiation or specialisation of interest. Replicating the in vivo signals that lead to stem cell specialisation is a difficult task and is made even harder if the culture process itself leads to inconsistencies or damage to the samples.

Stem cells have huge promise to contribute to a wide range of research and healthcare settings, and the ability to reliably culture samples is a cornerstone of future research.

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