Stem Cell Research

Embryonic stem cell research will prolong life, improve life ad give hope for life to millions of people.

-Jim Ramstad

What are they?

• Stem cells are undifferentiated cells.

• They can differentiate into specialized cells.

• They can divide (through mitosis) to produce more stem cells.

• They are found in multicellular organisms. In mammals.

• This slide shows an adult stem cell

Stem Cell Types

• In mammals, there are two types of stem cells.

• Embryonic stem cells, which are isolated from the inner cell mass of blastocysts.

• Adult stem cells, which are found in various tissues.

Repair System

• In adult organisms, stem cells act as a repair system for the body, replenishing adult tissues.

• This cross section of skeletal muscle fibers shows the small satellite cells.

• If the muscle fiber is damaged the satellite cells will reproduce and differentiate into muscle tissue and repair the damaged area.

Adult stem cells

• Three easy sources.• Bone marrow, which is

extracted by harvesting, that is, drilling into bone (typically the femur or iliac crest).

• Adipose tissue (lipid cells), which requires extraction by liposuction.

• Blood, which requires extraction through pheresis, wherein blood is drawn from the donor (similar to a blood donation), passed through a machine that extracts the stem cells and returns other portions of the blood to the donor.

Bone Marrow transplant

• Bone marrow contains multipotent stem cells.

• These cells can become RBC’s, WBC’s or platelets.

• The marrow can be harvested from a healthy donor and transfused into a patient with leukemia.

Spray on Skin

• Some healthy skin stem cells (unipotent – keratinocytes or fibrocytes) are mixed with water.

• The solution is sprayed on the burn or damaged area.

• The cells divide and produce new skin within days.

This young toddlers second degree burns were healed with the spray on skin technique.

Autologous stem cells• Stem cells can also be

taken from umbilical cord blood just after birth.

• Of all stem cell types, autologous harvesting involves the least risk.

• Autologous cells are obtained from one's own body.

• A person can save his or her own stem cells in the same way they can save their own blood.

The case for Embryonic stem cells

• The most potent stem cells are the embryonic stem cells taken from the blastocyst stage.

• These cells have the capability of differentiating into any tissue cell.

• They are also ideal in that they keep replicating indefinitely.

• There are over 300 existing human embryonic stem cell lines available in the world; about two-thirds of these are in just five countries: UK, Sweden, France, Spain, USA

Harvesting Embryonic Stem Cells

• In vitro fertilization generates multiple embryos.

• Some of the embryos are not clinically used or are unsuitable for implantation into the patient.

• These embryo’s may be donated by the donor with consent.

• Human embryonic stem cells are derived from these donated embryos that would otherwise be discarded.

Ethical objections

• Some people feel that it isn’t right to kill an embryo, even if it is going to be discarded, to obtain stem cells.

• They feel that once an egg is fertilized it is a distinct human life.

• This feeling has resulted in a moratorium on federal funding for embryonic stem cell research.

Chimeras

• Chimeras are organisms that contain cells or tissues from more than one organism.

• For example human stem cells can be transplanted into mice to make sure that the tissues that develop will function. (pancreatic cell research for diabetes).

• New therapies need to be tried on animals before humans.

• Some worry about a chimera with human consciousness or introducing human stem cells into a primate (chimp).

Human Chimerism

• This happens when two separate, fertilized eggs fuse to form one embryo.

• This results in an organism with intermingled cell lines.

• This person may have a liver with one set of chromosomes and a kidney with another.

• Most never now their situation.

• They may have different eye colors, faint marks on the back, or differential hair growth

Cloning

• Cloning and stem cell research are linked with a technique called Nuclear transfer.

• Scientists can transfer a nucleus from an adult stem ceel into an ovum or egg whose nucleus has been removed.

• This would result in identical genetic matches leading to safer tissue transplants.

• The fear of a lab growing a complete person has led to the practice being outlawed.

Mammoth• Recently a well preserved 10,000 year old frozen mammoth was discovered.

• It has been proposed to take stem cells from the mammoth and implant the nucleus into an elephant egg.

• Repeat the process over time and eventually you would have a mammoth!