Re: Jill - stuff

[Guest guest]

THis is a long one, I'm reproducing it.

BTW, w/o google I would be Ms Slyme Braine.

I could not recall Pamela Weintraub's name. I was just sitting here

thinking, I read the reference originally on sci-med...I remembered

that it was published at biomednet...I thought, what is her name? She

was married to...DIck Teresi...they both worked at Omni...what is her

name? I remember her ex-husband's name, and the magazine they worked

at, but what was her name...

I could not remember! But I googled " biomednet lyme " on google groups

and got to it. Have fun.

: Nick said this to me on the phone, I think they tested

only 2 patients.

Both & , I don't read this group much so if I don't get back

on here for a while, don't take it personally.

Here you go:

Posted May 25, 2001 · Issue 103 HMS BEAGLE

Magazine: Profile

http://news.bmn.com/hmsbeagle/­103/notes/profile

PROFILE

Growing Cells in 3-D

Breaking the Flat Barrier with Microgravity

by Pamela Weintraub

------------------------------­------------------------------­----------

-------

Abstract

Traditional cell culture models flatten the three-dimensional

landscape of the

human body into a one-cell-thick slab. NASA's bioreactor has given a

new depth

to these cultures and provided insights into HIV infection and Lyme

disease.

------------------------------­------------------------------­----------

--------

Doctors practicing evidence-based medicine - the judicious use of

external

evidence to help determine treatment - often look to studies based on

cells in

culture as strategic guides. After all, when dealing with infectious

agents

like HIV or autoimmune illnesses like arthritis, it is often

impossible to peer

into the human body itself. Without outside evidence, how can

practitioners

know with any precision what is really going on? Yet the journey from

theory to

practice has been slippery, largely because the culture studies often

cited,

even the most rigorous of them, are flawed. The reason: A vast

difference

between tissue inside the body and tissue in the lab. In the body,

complex

genetic instructions and a host of messages from the environment

cause cells to

differentiate into specific organs and tissue types. But in the petri

dish, the

fundamental law of bench biology known as " contact inhibition " rules.

In this

unyielding phenomenon, replicating cells stop dividing once they

sense

neighbors, resulting in tissue just one layer thick.

Scientists had been unable to culture cells in 3-D.

Because of contact inhibition, medical science has been unable to

culture human

tissue to the mature states of differentiation found in the body.

While

physicians often look to studies based on these cultures to guide

their

treatment decisions, they cannot really know if the data is relevant

and to

what degree.

But now all that may change. Through one of the most important

technologies to

trickle down from NASA since the inception of the space program,

biologists can

conduct experiments with three-dimensional tissue right here on

Earth. NASA's

great enabler is the bioreactor, a cylindrical chamber that bathes

tissue in

microgravity - the same near-weightless condition astronauts

experience during

their walks in space. Rotating slowly at the speed of a long-playing

record

album (33 RPM), the bioreactor keeps cells suspended relative to each

other, as

if the force of gravity were almost zero, allowing cells to grow in

three

dimensions (as happens in life) instead of just two dimensions.

Traditional cell cultures are limited.

The epicenter of this work, planetside, is the laboratory of

Zimmerberg,

chief of the Laboratory of Cellular and Molecular Biophysics at the

National

Institute of Child Health and Human Development, National Institutes

of Health,

in Bethesda, land. A number of years back, hoping to drill down

into the

process that ensues when HIV infects lymphoid tissue, Zimmerberg

found himself

limited by experimental design. When growing cells in laboratory

culture that

was flat as a pancake, he knew his findings would be of just limited

use. " For

instance, we knew that human tissue contained literally 100 times as

many

immune cells inside than at the periphery, " Zimmerberg notes. Yet in

the petri

dish,

" periphery " was all he had.

The problems were underlined by Leonid Margolis, Zimmerberg's

colleague and

chief of the Unit on Intercellular Interactions in his lab. Margolis

had spent

his career showing that the biology of any given cell depends upon

its complex

interaction with the tissue surrounding it and vice versa. Depending

upon a

series of adhesions and attachments, both invading cells and tissues

change

their genetic expression and physiological form over time. It is

through such

interaction, Margolis showed, that the pathology of any given disease

is

defined.

Ultimately, we want to understand cell behavior.

" As biologists, we do reductionist science in the test tube, "

Zimmerberg says,

" and through that means, we learn a lot. But ultimately, if we want

to

understand cell behavior, if we want to know the relevance of our

findings,

we've got to find a situation that approximates the living organism.

There is a

relationship between the disease state and the pathology of the

tissue, but the

cultures we'd been using were not up to the job. "

Zimmerberg was pondering these problems in 1995, he says, " when

someone handed

me a proposal from NASA. " The space agency was seeking a group to

study

biological complexity using its new microgravity chamber. The synergy

could not

have been more appropriate, and a partnership was born. One of the

most

important advances to emerge from that partnership is a tissue model

of AIDS,

one that closely resembles pathology in a living host. " AIDS is the

first

pandemic to start in the era of molecular biology, " says

Margolis. " As a

result, we know much about the molecules encoded by the viral genome.

In

contrast, however, we know relatively little about the mechanisms of

viral

pathogenesis. AIDS is a complex disease, in part because HIV infects

the cells

that fight infection and disrupts multiple, little understood cell

interactions

in the lymphoid system. Moreover, the virus evolves rapidly and

continuously

over many years in the body under as-yet-unidentified selective

pressures, and

its properties can be strikingly different early in infection

compared with

later, when severe immunodeficiency occurs. " In short, HIV infection

involves a

complex interplay between both infected and noninfected cells of the

human

immune system - a situation that is simply impossible to study with

tissue one

cell layer thick.

Impossible in the petri plate, doable in the bioreactor.

But what was impossible in the petri dish became doable in the

bioreactor,

enabling researchers to resolve some long-standing mysteries with

ease. One

issue confounding AIDS researchers, for instance, was the observation

in

standard culture of a phenomenon known as syncytia, in which viral

particles

fuse together, forming aggregate " cells " with many nuclei instead of

one.

Despite the fact that syncytia had never been observed in tissue,

scientists

thought this trait so important they used it to classify HIV strains.

Margolis and Zimmerberg were the first researchers to prove that

syncytia do

indeed occur in living tissue when they examined HIV-infected tissue

in the

bioreactor, but there was a catch. In the body, the syncytia in

lymphoid tissue

are destroyed almost instantly by the body's cells. The

classification system

based on observations in flat-dish cultures is not particularly

relevant, after

all.

Researchers replaced a vague HIV classification system.

As a result of this and other studies, a vague and controversial

classification

system based on the complex interaction of HIV with particular cells

has now

been replaced by one built on the firmer basis of viral molecular

characteristics. " This new classification may have a profound impact

on HIV

research, similar to the impact of Mendeleev's periodic table on

chemistry, "

says Margolis. The task ahead, he adds, is using molecular biology to

understand how HIV impairs living tissue and causes AIDS.

Toward that end, current work focuses on the transmission of AIDS

during the

earliest days of infection. To marshal the power of simulated

microgravity, the

scientists use a special, dual-chamber bioreactor divided by a

lifelike

membrane wall; uninfected tissue is cultured on one side of the

divide and

tissue biopsies from patients with known disease on the other. One

goal, says

Zimmerberg, is to see which strains of HIV are transmitted most

efficiently.

Another goal is the determination of conditions least and most

conducive to

transmission of the disease. Says Zimmerberg: " We plan to use this

model of

transmission to test methods of preventing vaginal and rectal

transmission at

the point of entry. "

How does Borrelia burgdorferi " adapt " to different human tissues?

Working with Duray, Division of Clinical Sciences Laboratory of

Pathology

Branch, National Cancer Institute, National Institutes of Health,

Zimmerberg is

also using the bioreactor to study the pathology of Lyme disease, a

multisystemic illness caused by infection with the spirochete

Borrelia

burgdorferi (Bb) and the most common vector-borne infection in the

United

States. " The Bb spirochete is able to persistently infect humans and

animals

for months or years in the presence of an active immune response and

is able to

'adapt' to distant human tissue such as the brain, liver, and joint, "

Zimmerberg explains. But how do the spirochetes do it? The recent

isolation of

p100, a glycoprotein expressed in the spirochetes upon invasion of

human brain

tissue, supports his theory that Bb undergoes genetic alteration

based on

contact with specific tissues. The genetic changes not only cause

expression of

new proteins, he surmises, but also facilitate attraction to and

invasion of

the tissue that sparked the change in the first place. Using the

bioreactor,

Zimmerberg hopes to isolate the genes and proteins expressed at

different

points during the course of infection.

Though the molecular pathways have yet to be unraveled, the

bioreactor has

already revealed an important piece of new information. Scientists

culturing

the Bb spirochete in the past have puzzled over what seemed to be a

contradiction - while infected tissue grown in standard culture could

sustain

just small numbers of spirochetes, the severity of patients' symptoms

were

often off the charts. What could be making these people so sick if

the

bacterial load is so small? To scientists working with " pancake

cultures " and

other, less direct means of detection, an autoimmune reaction seemed

a likely

answer. But Zimmerberg and his team have found that when grown in the

bioreactor, tissues present with

" exponentially more Borrelia, " probably because, as in AIDS, the

immune system

of the infected tissue is repressed. While Margolis's and

Zimmerberg's teams

continue to look for any evidence of an autoimmune reaction in their

bioreactor

work, they now know that many symptoms can be explained by the

persistence of

the disease.

Microgravity aids the study of many more diseases.

In addition to HIV and Lyme disease, Zimmerberg's team has been

studying

prostate disease, cyclospora (an intestinal parasite), herpes,

diabetes,

rheumatoid arthritis, squamous metaphasia (thought to be a precursor

to skin

cancer), and skin cancer. In work with NASA, they are also studying

the immune

system under conditions of microgravity to see whether astronauts on

extended

space missions might be at greater risk.

The team is also using the microgravity chamber to bioengineer tissue

for the

next generation of work. " We're using this technology to prepare

better models

of human colon, prostate, breast, and ovarian tumors, " Zimmerberg

states.

" While cells grown in conventional culture systems may not

differentiate to

form a tumor typical of the cancer of origin, tumors that form in the

bioreactor resemble the original tumor. " Similar results have been

observed

with normal human tissues, including cartilage, bone marrow, heart

muscle,

skeletal muscle, pancreatic islet cells, liver cells, and kidney

cells, to name

a few. The ultimate goal is creation of what Zimmerberg calls " a

universal

pathogen culture, " nothing less than a " multitissue equivalent that

creates the

necessary microenvironment " for most forms of human disease.

Can cells sense small changes in gravity?

The work also has raised some fascinating possibilities about the

nature of

cells in particular and life writ large. For instance, the

experiments hint at

the possibility that cells may be able to sense small changes in

gravity. " If

cells have sensors for gravity, " notes Zimmerberg, " we'd have to

rethink our

models, because we have missed something major. Cells that could

sense gravity

would represent a paradigm shift in the way life works. "

The next step for Zimmerberg and Margolis is conducting bioreactor

experiments

in space, where gravitational forces will be truly lower, reducing

stress

enough to grow larger tissue samples that live longer and approximate

conditions within the body more precisely than is possible now.

Zimmerberg

thinks that better culturing conditions could change the way life

science is

done. " The culturing of cells on solid substrate is the most popular

technique

in the entire biomedical enterprise, " he says. " Just as the culturing

of

bacteria led to nineteenth century advances, the culturing of animal

cells has

fueled the tremendous progress of the twentieth century. But, despite

a

hundred-year history for cell culture, there are still limitations.

Cells in

tissues within patients do not respond to therapeutics like cell

lines selected

for quick growth on the inner surfaces of flat flasks. Even in

primary culture,

we lose the location of a cell within the logic of the tissue

structure. There

are disease states whose pathology cannot be reproduced merely by

growing the

right cells. Rather, a complex interplay of cell-cell interactions on

a matrix

of extracellular material, bathed in the body's biochemicals,

dominate diseases

like HIV, diabetes, and Lyme. We simply do not have model systems for

these and

many other diseases we would like to study in vitro. Yet our

tremendous ability

to fish out individual molecules and learn their activities makes us

yearn to

understand their significance in the pathology of the disease. "

Pamela Weintraub is a former staff writer at Discover, former editor

in chief

of Omni, and the author of 15 books on health and science.

[Guest guest]

Ah, I had thought you were talking about an in vivo finding. But

this is good to know about too - muchas gracias.

" jill1313 " <jenbooks13@h...> wrote:

>

> THis is a long one, I'm reproducing it. [...]