Imagine two people are listening to music.

What are the odds

that they are listening

to the exact same playlist?

Probably pretty low.

After all, everyone has very different tastes in music.

Now, what are the odds

that your body will need

the exact same medical care and treatment

as another person's body?

Even lower.

As we go through our lives,

each of us will have very different needs

for our own healthcare.

Scientists and doctors are constantly researching ways

to make medicine more personalized.

One way they are doing this

is by researching stem cells.

Stem cells are cells that are undifferentiated,

meaning they do not have a specific job or function.

While skin cells protect your body,

muscle cells contract,

and nerve cells send signals,

stem cells do not have any specific structures or functions.

Stem cells do have the potential

to become all other kinds of cells in your body.

Your body uses stem cells

to replace worn-out cells when they die.

For example, you completely replace

the lining of your intestines every four days.

Stem cells beneath the lining of your intestines

replace these cells as they wear out.

Scientists hope that stem cells could be used

to create a very special kind of personalized medicine

in which we could replace your own body parts with,

well, your own body parts.

Stem cell researchers are working hard

to find ways in which to use stem cells

to create new tissue

to replace the parts of organs

that are damaged by injury or disease.

Using stem cells to replace damaged bodily tissue

is called regenerative medicine.

For example, scientists currently use stem cells

to treat patients with blood diseases

such as leukemia.

Leukemia is a form of cancer

that affects your bone marrow.

Bone marrow is the spongy tissue inside your bones

where your blood cells are created.

In leukemia, some of the cells inside your bone marrow

grow uncontrollably, crowding out the healthy stem cells

that form your blood cells.

Some leukemia patients can receive

a stem cell transplant.

These new stem cells will create

the blood cells needed by the patient's body.

There are actually multiple kinds

of stem cells that scientists can use

for medical treatments and research.

Adult stem cells or tissue-specific stem cells

are found in small numbers

in most of your body's tissues.

Tissue-specific stem cells replace

the existing cells in your organs

as they wear out and die.

Embryonic stem cells are created

from leftover embryos that are willingly donated

by patients from fertility clinics.

Unlike tissue-specific stem cells,

embryonic stem cells are pluripotent.

This means that they can be grown

into any kind of tissue in the body.

A third kind of stem cells

is called induced pluripotent stem cells.

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

that scientists have changed

to behave like embryonic stem cells.

Like embryonic stem cells,

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

While scientists and doctors hope to use

all of these kinds of stem cells

to create new tissue to heal your body,

they can also use stem cells

to help understand how the body works.

Scientists can watch stem cells develop

into tissue to understand the mechnanisms

that the body uses to create new tissue

in a controlled and regulated way.

Scientists hope that with more research,

they can not only develop specialized medicine

that is specific to your body

but also better understand

how your body functions,

both when it's healthy

and when it's not.