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Imagine two people are listening to music.

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What are the odds

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that they are listening

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to the exact same playlist?

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Probably pretty low.

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After all, everyone has very different tastes in music.

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Now, what are the odds

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that your body will need

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the exact same medical care and treatment

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as another person's body?

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Even lower.

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As we go through our lives,

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each of us will have very different needs

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for our own health care.

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Scientists and doctors are constantly researching ways

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to make medicine more personalized.

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One way they are doing this

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is by researching stem cells.

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Stem cells are cells that are undifferentiated,

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meaning they do not have a specific job or function.

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While skin cells protect your body,

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muscle cells contract,

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and nerve cells send signals,

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stem cells do not have any specific structures or functions.

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Stem cells do have the potential

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to become all other kinds of cells in your body.

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Your body uses stem cells

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to replace worn-out cells when they die.

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For example, you completely replace

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the lining of your intestines every four days.

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Stem cells below the lining of your intestines

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replace these cells as they wear out.

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Scientists hope that stem cells can be used

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to create a very special kind of personalized medicine

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in which we could replace your own body parts

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with, well, your own body parts.

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Stem cell researchers are working hard

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to find ways in which to use stem cells

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to create new tissue

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to replace the parts of organs

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that are damaged by injury or disease.

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Using stem cells to replace damaged bodily tissue

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is called regenerative medicine.

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For example, scientists currently use stem cells

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to treat patients with blood diseases

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such as leukemia.

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Leukemia is a form of cancer that affects your bone marrow.

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Bone marrow is the spongy tissue inside your bones

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where your blood cells are created.

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In leukemia, some of the cells inside your bone marrow

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grow uncontrollably, crowding out the healthy stem cells

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that form your blood cells.

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Some leukemia patients can receive

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a stem cell transplant.

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These new stem cells will create

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the blood cells needed by the patient's body.

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There are actually multiple kinds of stem cells

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that scientists can use for medical treatments and research.

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Adult stem cells or tissue-specific stem cells

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are found in small numbers in most of your body's tissues.

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Tissue-specific stem cells replace

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the existing cells in your organs

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as they wear out and die.

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Embryonic stem cells are created

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from leftover embryos that are willingly donated

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by patients from fertility clinics.

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Unlike tissue-specific stem cells,

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embryonic stem cells are pluripotent.

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This means that they can be grown

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into any kind of tissue in the body.

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A third kind of stem cells

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is called induced pluripotent stem cells.

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These are regular skin, fat, liver, or other cells

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that scientists have changed to behave

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like embryonic stem cells.

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Like embryonic stem cells,

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they, too, can become any kind of cell in the body.

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While scientists and doctors hope to use

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all these kinds of stem cells

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to create new tissue to heal your body,

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they can also use stem cells

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to help understand how the body works.

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Scientists can watch stem cells develop

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into tissue to understand the mechnanisms

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that the body uses to create new tissue

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in a controlled and regulated way.

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Scientists hope that with more research,

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they can not only develop specialized medicine

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that is specific to your body,

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but also better understand

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how your body functions,

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both when it's healthy

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and when it's not.