iPSC: Characteristics, Culture, Differentiation

Induced pluripotent stem cell (iPSC) is a pluripotent stem cell that is introduced to a series of inducing factors into mature somatic cells and reprogrammed into a type of pluripotent stem cell with characteristics similar to embryonic stem cells. It comes from a wide range of sources, avoids immune rejection, and provides a new research direction for the entire field of stem cell biology and clinical regenerative medicine.

Characteristics of the iPSC

• iPSC has unlimited proliferation potential in vitro and also forms tight, flat cell colonies similar to embryonic stem cells. iPS cells also have a morphology close to that of embryonic stem cells when cultured in vitro. Meanwhile, iPS cells also express some stem cell markers found in embryonic stem cells, such as Nanog proteins, SSEA-like proteins, and TRA-like proteins.
• iPSC has the potential to differentiate into three embryonic cells or tissues. iPSC can generate teratomas when injected into immunodeficient individuals, and iPSC cultured in suspension in vitro will differentiate to form embryoid bodies (EBs). However, the ability of iPSC to form chimeras is poor, and even attempts to generate chimeric mice using iPSC have failed.

Culture System

The environment for culturing iPSC is similar to that of embryonic stem cells. Traditionally, iPSC is cultured on a feeder consisting of mouse embryonic fibroblasts (MEF) inactivated by mitomycin or radiation and in a medium containing serum and leukemia inhibitory factor (LIF). Methods are also available for culturing iPSCs on chemically defined serum-free media without the use of feeder cells.

• Adherence culture system
  Adherence culture is a routine cell culture method that can utilize knowledge and experience from laboratory experiments to ensure optimal production of iPSC. To mass produce by adherence culture, there is a need for a large culture surface. Therefore, methods that can increase the culture surface area in the vessel are an important way to increase productivity.
• Suspension culture system
  Unlike adherent cultures, suspension cultures do not require an adherent surface, thus enabling the use of simpler and easily amplified containers. Aggregation control is very important during iPSC suspension culture, especially if fewer agglomerates are formed early on resulting in lower growth. Therefore, an ideal scenario is to generate many agglomerates of controlled size with sufficient cell-to-cell contact for stable growth.

iPSC Differentiation-Related Cytokines

The widespread use of iPSC is based on the ability to differentiate. Through different cytokines, iPSCs can differentiate into different types of cells. The common factors used to differentiate human iPSCs into various cell lines are GM-CSF, Activin A, DLL4, NOG, TNF-α, IL-2, VEGF, FGF, IL1β, EGF, and so on.

Reprogramming methods for iPSCs

• Integrated genome reprogramming
  Initial iPSC reprogramming studies utilized retroviral and lentiviral vectors to express reprogramming factors. Although retroviral and lentiviral vectors have proven to be powerful vectors for iPSC reprogramming, the major drawback of these delivery systems is the random integration of the viral genome carrying the transgene into the cellular genes.
• Non-integrated genome reprogramming
  Non-reprogramming systems include adenovirus, Sendai virus, episomal, and minicircles. None of these methods integrate into the cellular genome. Although each method has its unique features, the main requirements for generating iPSCs are potency and reproducibility.

Creative Bioarray Relevant Recommendations

Induced pluripotent stem cells (also known as iPS cells or iPSC) are a type of pluripotent stem cell that can be generated directly from adult cells. Creative Bioarray offers human iPSC lines derived from various primary cells by different inducing methods.