什么是干细胞?

What are Stem Cells?

Stem cells are special human cells that are able to develop into many different cell types to replace or repair the damaged cells in the body. Stem cells have two properties that distinguish them from other cell types. Stem cells can divide and result in daughter cells that either are replicates (self-renewal) or acquire features of more mature cell types (differentiation). The balance between these two outcomes may vary depending on the stem cell type and the context, but a stem cell must be capable of either.

Types of stem cells

There are three main types of stem cells:

  1. Embryonic stem cells
  2. Induced pluripotent stem cells
  3. Adult stem cells or Mesenchymal stem cells

Embryonic stem cells

The embryonic stem cells used in research today come from unused embryos. These result from an in vitro fertilization procedure. They are commonly used in scientific studies and disease models. These embryonic stem cells are pluripotent. This means that they can turn into all cell types.

Advantages: Embryonic stem cells can differentiate into Ectoderm, Mesoderm and Endoderm.
Disadvantages: It invovles the ethical concerns and might generate teratoma and develop into tumor stem cells.

Induced pluripotent stem cells

Induced pluripotent stem cells or iPS cells, are stem cells that scientists make in the laboratory.

‘Induced’ means that they are made in the lab by taking normal adult cells, like skin or blood cells, and reprogramming them to become stem cells.

Just like embryonic stem cells, they are pluripotent so they can develop into any cell type.

Advantages: It is widely used in medical research and drug testing as well as the disease model.
Disadvantages: It might generate the teratoma and develop into tumor stem cells.

Adult stem cells or Mesenchymal stem cells

Adult stem cells or Mesenchymal stem cells supply new cells as an organism grows and to replace cells that get damaged.

Adult stem cells or Mesenchymal stem cells are said to be multipotent, which means they can only change into some cells in the body, not any cell, for example:

Blood or hematopoietic stem cells can only replace the various types of cells in the blood lineage.

Skin or epithelial stem cells provide the different types of cells that make up our skin and hair.

Adipose tissue, body fat, or simply fat is also a good source for Mesenchymal stem cells, which can differentiate into bones, cartilages and muscles. 

Advantages: It can differentiate into bones, cartilages and muscles.
Remark: For some certain people, there might be slight possibility of allergic reactions with Allogenic Mesenchymal stem cells.