iTunes U: Med-Eds Harvard University of Health and Medicine

Standing on the Threshold: The Promise of Stem Cell Science

Douglas A. Melton, PhD. Xander University Professor of Stem Cell and Regenerative Biology

Regenerative Medicine:

stem cells to replace tissues

stem cells to screen for drugs that stop degenerative diseases

stem cells for healthy aging

Differentiated Cells Are Not Static:

cells are continually being renewed

intestine cells last a few days

blood cells last up to ten weeks

pancreas cells live for months to years

brain cells are nearly permanent

Degenerative Diseases:




Cardiovascular Disease



2 Essential Properties of Stem Cells:

self replicate (renew or regenerate themselves) and give rise to specialized cells

Human Embryotic Stem Cells

         Ectoderm: skin, brain, nerves

         Mesoderm: blood, heart, kidney, muscle, bone

         Endoderm: lung, liver, stomach, pancreas (size of banana), intestine

Making insulin- producing cells from stem cells:

 ES/IPS———-> Endoderm————> Pancreas———–> Endocrine———-> Insulin


While our nation is suffering from large financial defects, we’re also suffering from large beta cell defects. There are not enough beta cells in the population to manage  their glucose control leading to the epidemic of Type 2 Diabetes.

Making enough insulin-producing cells for a patient: 1 billion needed, nearly there……..

Making Human Heart Cells:

human embryonic stem cells—-> specialized cells——>reconstructing human heart cells

Making stem cells from skin: induced- pluripotent stem cells.

skin cells—–> add DNA or RNA encoding reprogramming factors—–> patient specific stem cells

Degenerative Diseases (stem cells can reconstruct the neurons and cells needed):

Alzheimer’s: forebrain neurons

Parkinson’s: midbrain neurons

ALS: motor neurons

Cardiovascular Diseases: cardiac muscle cells

Type 1 Diabetes: Pancreatic Beta Cells

Screening for drugs that increase motor neuron life:

   goal: to define a drug to treatment that will slow the degeneration

Experiment: old and young mice must share a blood stream O=OLD Y=YOUNG

When one is injured what happens? 

OY   + young repairs at its own healthy rate

YY   + a lot of red, new muscle cells

OO  – can not repair

YO   + Old  repairs at Young rate


1. Young blood improves muscle’s regeneration in old mice. Young blood contains factors that stimulate muscles stem cells in old animals. Old mouse’s blood is not poisoning the repairs (<—OY).

2. Young blood reduces cardiac size and improves elasticity in old mice.

3.Young blood enhances remyleination in old mice (brain).










Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s