The Prospect of

Cell Replacement Therapy

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How To Rescue Our Life

Disadvantage:

its scope is greatly limited by the availability of donor organs and the high risk of immunologic rejection .

Now: cell replacement therapy

Before: organ transplant

What is the cell replacement therapy

Example:

bone marrow transplantation in which cells are extracted from the interior of the pelvic bones of a donor and infused into the body of a recipient.

bone marrow transplantation

stem-cell insurance policy

Stem cells

Stem cells are defined as undifferentiated cells that are capable of self-renewal, that is, production of more cells like themselves, and are multipotent, that is, are capable of differentiating into two or more mature cell types.

An adult muscle stem cell

Figure 1a

A portion of a muscle fiber, with its many nuclei stained blue. A single stem cell (yellow) is seen to be lodged between the outer surface of the muscle fiber and an extracellular layer (or basement membrane), which is stained red. The undifferentiated stem cell exhibits this yellow color because it expresses a protein that is not present in the differentiated muscle fiber.

An adult muscle stem cell

Figure 1b

Adult stem cells undergoing differentiation into adipose (fat) cells in culture. Stem cells capable of this process are present in adult fat tissue and also bone marrow.

adult stem cells

Adult stem cells are an ideal system for cell replacement therapies because they can be isolated directly from the patient, grown in culture, and reintroduced back into the same patient .

ES cells might be used for cell replacement

The long-range goal of clinical researchers is to learn how to coax ES cells to differentiate in culture into each of the many cell types that might be used for cell replacement therapy. Considerable progress has been made in this pursuit, and numerous studies have shown that transplants of differentiated, ES-derived cells can improve the condition of animals with diseased or damaged organs.

the primary risk with this type of procedur

• the unnoticed presence of undifferentiated ES cells among the differentiated cell population, they are capable of forming teratoma.

• the culture of ES cells at the present time involves the use of nonhuman biological materials.

Figure 2

A procedure for obtaining differentiated cells for use in cell replacement therapy

The new type of cells---IPS cells

• Reprogram a fully differentiated cell

• Four genes: Oct4, Sox2, Klf4, Myc (play a key role in maintaining the cells in an undifferentiated state)

• The four genes were introduced into a fully differentiated cell using gene-carrying viruses

Figure 3

Steps taken to generate IPS cells for use in correcting the inherited disease sickle cell anemia in mice

IPS cells’ advantage and disadvantage

•IPS cells does not require embryo•IPS cells also stimulate an immune attack , however it will be much easier to generate personalized and tissue compatible•Undifferentiated IPS cells also give rise to teratomas•the method about Add 4 "reprogram" gene or replace defective genes of disease cells may have cause cancer side effects

Transdifferentiation

•One type of differentiated cell had been converted into another type of differentiated cell

•In this report

the acinar cells of the pancreas were transformed into pancreatic beta cells---by injection viruses that carried three genes known

Recent achievement

• 2009 Japanese scientists have four induce gene of two genes into cells. Cultivate IPS

• 2010 Boston's scientists discover new induction IPS cells cultivation techniques