Stem Cells and Cellular Differentiation and Organ Transplant - December 12, 2024

Cellular Differentiation

  • When a cell becomes specialized, it begins to show differences in shape, content, and function from those of surrounding cells.

  • This process is referred to as “cellular differentiation”

  • Cellular differentiation is directed by → the genetic information of the cell (DNA)

Stem Cells

  • Stem Cell: an undifferentiated cell that can divide to form specialized cells

  • A stem cell divides into two daughter cells through the processes of mitosis and cytokinesis

  • Each resulting daughter cell can develop into a different type of cell, based on which part of its DNA is switched on

  • In animals, a cell that can differentiate into various specialized cells is referred to as a “stem cell.”

  • They can differentiate into different types of tissue:

    • Epithelial

    • Muscle

    • Nerve

Two Main Forms of Stem Cells

  • Embryonic (pluripotent or omnipotent):

    • These stem cells can differentiate into any kind of cell

  • Tissue (adult) stem cells (multipotent):

    • These stem cells are limited to differentiating into certain types of cells:

      • Red blood cells

      • White blood cells

      • Platelets

Cell Blood Cell Banking

  • A rich source of stem cells is from the umbilical cord. They are more similar to tissue stem cells.

  • Have a high concentration of these tissues stem cells and is relatively easy to obtain

  • This blood could could be banked for future use if needed ex. Treatment of leukemia

Tissue Stem Cell Transplantation

  • Leukemia is a cancer that occurs in the bone marrow.

    • The stem cells that differentiate into blood cells divide uncontrollably, resulting in non-functioning blood cells.

  • Treating leukemia involved removing all the diseased white blood cells and killing the bone marrow completely.

  • Umbilical cord stem cells or bone marrow stem cells can treat leukemia.

Regeneration and Tissue Engineering

  • Regeneration refers to the ability of a tissue to repair itself

    • E.g. Skin, muscle and bone can re-grow and heal after an injury.

    • Nerve cells however, are unable toregnerated completely.

  • Tissue engineering → research focued on the regeneration of human body issue and parts

Organ Transplantation

  • Tissue transplants have been performed since the early 1800s, The first successful organ transplant (a kidney) occurred in 1954.

  • The list of organs that can be sucessfully transplanted now includes the heart, liver, lung, pancreas, and intestines.

  • Transplantable tissues include the cornea, skin, bone, bone marrow, tendons, and blood vessels

  • Some organs and tissue can be successfully and safely transplanted from living donors.

  • Other body parts can be taken only from deceased donors.

Benefits and Risks

  • Benefits of a donor is helping save a life and the benefit of a recipient is being able to live a healthy life.

  • Some risk associated are:

    • Rejection: recipients immune system may think the new organ is a foreign material and destroy it.

      • Drugs would be needed to prevent the immune system from rejecting

        • This could cause additional issues as the immune system is suppressed, reducing the body ability to fight off infection.

Organ Donor

  1. Living Donor Organs: Living donor organs come from a living person who chooses to donate a kidney, a lobe of one of their lungs, or a part of their liver.

    1. Living donors are usually relatives of the recipient which increases the chance that the organ offered and being an appropriate genetic match, and the risk of rejection is minimized.

    2. Risk: In the normal body, duplicate organs mean that if one organ fails, the other still functions. This backup system is lost or reduced after donation.

  2. Deceased Donor Organs: The decision to make a donation is usually done when the patient is alive but family members can give consent to donate if the donor card is not signed.

    1. When a potential organ donor dies, the organs must be checked to determine if they are healthy and undamaged.

    2. Medical professionals take many factors into account, including blood and tissue types, the ages and locations of the donor and the recipient, and how long the recipient has been waiting for a transplant.

  3. Xenotransplantation

    1. Is the transplanting of body parts from one species to another. Ex. Heart valves from pigs have already been used to replace damaged human heart valves.