Roberta Friedman, Ph.D.Special to BioWorld

Scientists at Advanced Tissue Sciences Inc. reported onTuesday a method to isolate and propagate stem cells thatinvolves magnetic particles coated with antibodies.

Stem cells, which can generate all the cells of the blood, wereisolated from rat bone marrow by a monoclonal antibody thatrecognizes a cell surface marker called Thy 1.1. The isolationtechnique involved immunomagnetic microspheres, tinymagnetic particles coated with antibodies. After the antibodiespull out the stem cells, the microspheres can be isolated by amagnet, allowing the attached cells to be collected.

The stem cells are then allowed to proliferate in culture onnylon screen supports. At the Federation of the AmericanSociety of Experimental Biology in Anaheim, Calif., ATSreported up to 700 percent increases in the proportion of stemcells in the resulting cultures, compared with the proportion inthe original culture.

"Our ability to replicate these cells will be an importantcontribution to bone marrow transplantation," said GailNaughton, executive vice president and chief operating officerof the La Jolla, Calif., company (NASDAQ:ATISA).

The company this week also reported data on several tissueculture systems based on its core technology. Among them is abiodegradable mesh that bears engineered cells.

At the Keystone Gene Transfer Symposium, ATS presentedresults of its polymer scaffolds containing cells engineered witha reporter gene. Grafted into the skin of rodents, the gene wasseen to function for at least 60 days in mice, and for more than90 days in rats.

Advantages of delivering gene therapy by a skin graft includeminimal surgery and release of protein into the bloodstream, aswell as the accessibility of skin for monitoring survival of thegene-bearing cells.

"We are starting to look for a corporate partner to expand theapplication of our delivery system," said Naughton.

ATS also is working on the ability of placental or umbilicalstromal tissue to stimulate the growth of natural killer cells inthe culture system. Natural killer cells could be used in cancerimmunotherapy if enough of them can be generated by thisapproach, Naughton said.

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