Induced pluripotent stem cell
Pluripotent stem cells can be obtained through two primary methods: isolation from embryos (embryonic stem cells, ESCs) and reprogramming of adult cells (induced pluripotent stem cells, iPSCs). Each method has its ethical considerations and technical challenges.
Isolation of Embryonic Stem Cells (ESCs):
Source: ESCs are derived from the inner cell mass of a developing blastocyst, typically obtained from early-stage embryos.
Process: Embryos are usually created through in vitro fertilization (IVF) or other assisted reproductive techniques. The inner cell mass is isolated from the blastocyst. Cells from the inner cell mass are cultured in specific conditions that support their pluripotent state.
Induced Pluripotent Stem Cells (iPSCs):
Source: iPSCs are generated by reprogramming adult cells, typically obtained from skin or blood.
Process: Somatic cells (e.g., skin fibroblasts or blood cells) are collected from the individual who will be the source of the iPSCs. These cells are then reprogrammed to a pluripotent state by introducing specific transcription factors, typically Oct4, Sox2, Klf4, and c-Myc (known as the Yamanaka factors). The reprogrammed cells transition to a state resembling that of embryonic stem cells. Steps for Generating iPSCs:
Cell Isolation:
Obtain a sample of somatic cells (e.g., skin fibroblasts) from the individual. Reprogramming:
Introduce the Yamanaka factors into the somatic cells using viral vectors or other methods. These factors induce the cells to become pluripotent. Culturing iPSCs:
Culture the reprogrammed cells in conditions that support pluripotency, typically on feeder cells or using defined culture media. Characterization:
Confirm the pluripotency of the generated iPSCs through various assays, including gene expression analysis, immunocytochemistry, and teratoma formation assays. Both methods have advantages and disadvantages. ESCs are considered more “naive” and may have a broader differentiation potential, but their use is associated with ethical concerns related to the destruction of embryos. iPSCs, on the other hand, avoid these ethical concerns and allow for the generation of patient-specific cells for potential therapeutic applications. However, iPSCs may retain certain epigenetic memory from their somatic cell origin and can be more challenging to fully reprogram.
The choice of method often depends on the specific goals of the research or therapeutic application and ethical considerations.
Induced pluripotent stem cells (also known as iPS cells or iPSCs) are a type of pluripotent stem cell that can be generated directly from adult cells. The iPSC technology was pioneered by Shinya Yamanaka’s lab in Kyoto, Japan, who showed in 2006 that the introduction of four specific genes encoding transcription factors could convert adult cells into pluripotent stem cells.
He was awarded the 2012 Nobel Prize along with Sir John Gurdon “for the discovery that mature cells can be reprogrammed to become pluripotent.”
Brain organoids are three-dimensional tissue cultures derived from human pluripotent stem cells, such as induced pluripotent stem cells (iPSCs) or embryonic stem cells. These organoids are designed to mimic certain aspects of the developing human brain, providing researchers with a valuable tool for studying brain development, neurological disorders, and potential therapeutic interventions