7. Stem cell therapies

Stem cell

An undifferentiated cell that can divide to produce some offspring cells that continue as stem cells and some cells that are destined to differentiate (become specialized).

What are two defining qualities of stem cells?

• They can self-renew (a property that makes cells live longer)

• They can differentiate into specialized mature cells

Stem cell therapy

Stem cell therpay is utilised in regenerative medicine. It can be used to repair tissues/organs rather than treating symptoms or replace defective/diseased cells with new functional cells

Totipotent stem cells

Totipotent stem cells can give rise to an organism: e.g. a zygote. cells can produce a complete organism. “Toti” means whole

Pluripotent stem cells

Pluripotent stem cells can give rise to all three germ layers (mesoderm, endoderm and ectoderm) but not extraembryonic structures: e.g. embryonic stem cells. “Pluri” means many

Multipotent stem cells

Multipotent stem cells are adult stem cells, e.g a neutral stem cell or a hematopoietic stem cell. “Multi” means several. They are tissue-specific and hard to access and isolate

Current limitation for stem cell therapies

• Ethical concerns 

• Immune rejection 

• Tumorigenicity

• Safety and regulatory challenges

Challenges and considerations for stem cell therapies

• Overcoming scarcity by expanding stem cells ex vivo.

• Ensuring safety through quality control, avoiding tumorigenicity, and addressing immunogenicity concerns.

Cord blood advantages

• Increased donor availability (every child that is born every day, great availability) 

• Non-invasive process

• Lower risk of GvHD (Doesn’t have the same degree of  immune cells as adults)

• Reduced need for HLA (human leukocyte antigen) matching

Cord blood disadvantage

• Limited HSC number

Steps to circumvent ethical issues of embryonic stem cells

Derivation of ES cell lines without destroying the embryo

Steps to circumvent immune rejection of embryonic stem cells

• Biobanking: ES cell bank with ES cell lines derived from HLA haplotypes commonly found in the population

• Somatic cell nuclear transfer (SCNT): production of ES cells from the patients themselves by therapeutic cloning. Embryonic cells from the person directly and the patient will not reject it