I was given two frozen vials of embryonic stem cells.

Each vial cost $5,000.

And my boss said, "Now you grow them."

That was ten years ago.

And now look at my lab.

We grow the cells routinely.

For me, it's such a good thing

to see how the science has progressed in this field.

Hi, I'm Amy Adams with California's Stem Cell Agency.

We asked you to submit questions

about Parkinson's disease and stem cell research

through our blog, Facebook, and Twitter.

Today we're at the Buck Institute for Research on Aging,

where Dr. Xianmin Zeng

is going to answer those questions

and also talk about her own Parkinson's disease research.

Let's go in.

Can you start by telling us

a little bit about Parkinson's disease,

what it is and what the symptoms are?

Parkinson's disease is a neurodegenerative disorder

which leads to progressive deterioration

of motor function,

and the cause is the loss of dopamine-producing nerve cells

in part of the midbrain called Substantia Nigra.

The primary symptoms for Parkinson's disease

is tremor, slowness in movement,

impaired balance, and stiffness.

It was ten years ago when you first started working with...

embryonic stem cells and Parkinson's disease.

Now you're getting close to clinical trials.

It is a long, slow path to get in to people.

What keeps you motivated?

I would say... to keep me motivated is...

My goal is to make a difference.

My hope is that what I'm working now today

will someday benefit the patient.

And at this moment,

we have decided on an embryonic stem cell line

which we know can be used for clinical purpose,

and we have generated two lots of dopaminergic neurons

suitable for direct transplantation into the brain

to hope those cells

will replace the lost cells and function in the brain.

So we are now in a position to go to the FDA

to file for a phase 1 clinical trial

in the next two years, that's my estimation,

so, in hoping that we would be able to run a clinical trial

in the next three to five years.

Why do we need a cure for the disease?

Because it's a terrible disease,

and there are about one million Americans suffer the disease,

and with the aging population now,

the number is expected to increase,

and about 40% of the people

affected by Parkinson's disease are under the age of 60.

So there is a clear impact of society

in terms of losing productivity.

One of the people who wrote in and asked us a question

said that the person's grandfather had Parkinson's disease,

"so what is the likelihood that I will also get it?"

Parkinson's disease, first of all,

is a disease described as a sporadic disease,

which means, actually, you don't know the cause.

85% of the Parkinson's disease cases are sporadic,

so the chance that one person's grandfather has the disease,

it may increase the person's chance of having the disease,

but keep in mind that the disease is more sporadic.

So, you began working with embryonic stem cells

right at the very beginning,

and then since that time,

people have learned how to reprogram adult cells

like skin cells, into an embryonic-like state,

so they are more or less equivalent to embryonic stem cells,

and these are the iPS cells that we hear about a lot.

And you're now working with embryonic cells

and iPS cells.

Why do you work with both cell types?

Because iPS cells provided additional cell source

for producing the right type of dopaminergic neurons,

also because you now have a cell source

coming from both normal and patient subjects,

and you can use the cells to test different drugs

to be better predictor of the potential clinical benefit.

So a person wrote in asking about the different types of stem cells.

The person asked, "What types of stem cells

are best suited for treating Parkinson's disease?"

I think this is a question nobody can now provide an answer,

and that's why people need to work

with different types of the stem cells

in order to find out exactly this question:

What type of the stem cells is the best?

So that's why I'm working on both ES cells and iPS cells.

There are a lot of people working in the field,

and with the funding, with the right timing,

and the right training,

we're ready to make new discoveries.