Cartilage Made From Stem Cells Tested In Animals

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Cartilage Made From Stem Cells Tested In Animals

ARLINGTON, Va., April 11, 2002 --- The research lab that made headlines

last year for turning fat cells into cartilage has taken the work a step

further by successfully implanting the altered cells in mice.

This demonstrates the potential of taking stem cells from one tissue and

turning them into cells of other tissues for use as implants in treating

injury and disease.

Since cartilage has few blood vessels, nerves and lymphatic support, it

has a limited capacity for repair when damaged. This makes cartilage an

especially good candidate for replacement by engineered tissue.

" For patients with tissue damage, we envision being able to remove a

small piece of fat, and then growing customized, three-dimensional pieces

of tissue which would then be surgically implanted where needed, " said

Whitaker investigator Farshid Guilak, Ph.D., director of orthopedic

research at Duke University.

Guilak and his colleagues have also used fat cells to produced cells that

can make bone and, of course, fat. The ultimate goal of the work is to

develop replacement cells and tissues by tapping into the regenerative

power of stem cells.

Stem cells are the mother cells of various tissues of the body. They

reproduce themselves and, at the same time, give rise to different cell

types that become skin, bone, blood and other living tissues.

Recent research suggests that stem cells from one tissue can be

reprogrammed to make cells of another tissue. The ability to isolate and

manipulate stem cells have opened new avenues of research for treating

injury and disease.

Embryonic stem cells can develop into virtually any cell type in the

body. They are the subjects of widespread interest and controversy.

President Bush has stopped federally funded research involving new lines

of embryonic stem cells. This has accelerated the search for stem cells

in adult tissue.

" We have found a new source of adult stem cells that can be changed into

different cells and tissues, " said M. Quinn Wickham, a Duke University

medical student who works in Guilak's lab.

In the animal studies, fat cells left over from liposuction were filtered

to isolate a colony of cells rich in stem cells. These were grown in a

chemical and physical environment that encourages the growth of

cartilage. It was important to feed the cells growth factors and culture

them in a three-dimensional configuration to simulate the way cartilage

cells grow naturally.

Fat cells grown in this way began to produce collagen, a main ingredient

of cartilage. When these cells were implanted under the skin of mice,

they continued for three months to produce collagen and other ingredients

in a matrix characteristic of cartilage.

It is unlikely that one source of stem cells can be used to treat a wide

variety of medical problems and disease, Guilak said. " But different

clinical problems could be addressed by using adult cells taken from

different spots throughout the body, without the same ethical concerns

associated with embryonic stem cells. "

Results of the study were published in the journal Biochemical and

Biophysical Research Communications.

In a related study, fat cells were taken from a pad of fat that lies

behind the knee cap (patella). Cells can be harvested from this area

using a minimally invasive procedure that is less disruptive than

liposuction. Similar deposits are also found in various other connective

tissues throughout the body.

The researchers took fat pads from patients whose knee joints were

removed during total joint replacement surgery and extracted a population

of connective tissue (stromal) cells believed to be rich in stem cells.

Three groups of these cells were placed in three different environments

and given steroids and growth factors that would encourage the growth of

cartilage, bone and fat.

After a period of weeks, the cell cultures were examined. The first group

had developed collagen matrix molecules characteristic of cartilage. The

second group developed calcium phosphate deposits as if they were

beginning to build a structure of bone. The third group began producing

fat cells.

The results suggest that stem cells taken from fatty tissue can be

reprogrammed into various other types of cells.

Any human applications of this work would be years away, but the research

group is encouraged and continuing the work. Collaborating with the Duke

team was Dr. Jeff Gimble of Durham, N.C.-based Artecel Sciences, who

holds the patent for the process of isolating these cells from fat.

Guilak is a consultant for Artecel Sciences.