Stem cells and regenerative medicine

Stem cell properties

Capable of self-renewal, unspecialized

Environmental Asymmetry

Environmental factors can lead a stem cell to differentiate

Divisional asymmetry

After a stem cell divides, the daughter cells may be different (uneven cell division) → one may differentiate

Progenitor

A stem cell that underwent differentiation

Totipotent

Can differentiate into any cell

Example of totipotent cells

Zygotic cells

Pluripotent

Can differentiate into cells of all three germ layers (endoderm, ectoderm, mesoderm)

Example of pluripotent stem cells

Embryonic cells

Multipotent

Can differentiate into some cells

Example of multipotent cells

Common adult stem cells

Unipotent stem cells

Can only differentiate into one type of specialized cell

Example of unipotent stem cells

Spermatogonia stem cells

Induced pluripotent stem cells (IPSCs)

Adding defined factors to fibroblasts

CRISPR-Cas9 Technology

Can be used to edit the genome of an organism

Issues with obtaining embryonic stem cells

Limited availability of embryos, ethical issues,

Shinya Yamanaka

Derived mouse IPSCs in 2006 and human IPSCs in 2007

Mesenchymal stem cells

Derived from bone marrow

Property of mesenchymal stem cells

Higher proliferation rate

Applications of stem cell therapy in regenerative medicine

• stem cell therapy

• tissue engineering

• tissue repair

Challenges of stem cell therapy

• Potential for rejection

• Potential to differentiate into unwanted cell type

• Uncontrolled proliferation → tumour formation