The Walter Reed Army Institute of Research (WRAIR) spacetissue loss (STL) project, the military's top-ranking life sciencesproject, will send 16 billion cells into space aboard the shuttleDiscovery next week to further investigate the effect ofmicrogravity on cellular activity.
The mission, due to depart Dec. 2, will take a closer look ateffects studied on a flight in March that involved bone andmuscle cells, and will extend the scope of those studies toinclude immune and bone marrow cells, according to the STLprogram director, Col. W.P. Wiesmann of Walter Reed.
"A large part of the success of the program depends on thespecialized equipment used, the technology which drives thescience being performed in a hostile environment," saidWiesmann.
Cellco of Germantown, Md., helped develop culture conditionsand growth protocols for the STL's first flight in March, andsupplied its capillary cartridges that utilize the company'sartificial capillary cell culture technology.
WRAIR adapted Cellco's system to work in a sophisticated cellculture device, essentially a self-contained, automated 2-cubic-foot box capable of demonstrating that skeletal muscle tissueloss, blood cell depletion, loss of bone mass, heart muscledamage and immune system dysfunction may be a direct resultof zero gravity at the cellular level, explained Wiesmann.
Cellco's system allows human cell growth to be studied outsideof the body by simulating the natural, three-dimensionalfunction of the human capillary system. The cells grow within anetwork of artificial blood vessels perfused with an oxygen-rich nutrient liquid representative of a human capillary.
According to William Lynn, Cellco's chief executive officer andpresident, the main objective of the first flight was to bringback cells alive. Viable cells were returned, and they showedbiochemical differences between the space study and an earthstudy.
"We are trying to determine at the cellular level exactly whatcauses physiological changes as observed in astronauts," Lynnsaid. "And the key question is, how does the behavior of celltypes change without gravity to influence their interaction?"
Cellco will also supply bone marrow cells on the upcomingflight. Bone marrow stem cells (immature cells) don't grow wellon earth; they live only a short time or differentiate quickly tobecome white or red cells, making it difficult for immature cellsto multiply and grow, according to Wiesmann.
If immature bone marrow cells can proliferate in space withoutdifferentiation, Weismann said, the cells can be multiplied toproduce quantities large enough for human treatment.
The mission also will attempt to discover why bone cells didn'tcalcify and grow on the first flight, and why immature musclecells did not fuse to become adult cells, Weismann said.
This phenomena may imply a genetic mechanism in musclecells. One hypothesis, called mechanoreceptors, holds that whengravity is removed, the signals that aid cells in sensing andinteracting with their physical environment don't functionproperly, explained Wiesmann.
The STL will also be looking at the activity of immune cells,specifically macrophages -- white cells involved in controllinginfection -- and HL-60 (human leukemic) cells to model humanneutrophils, cell types that did not differentiate whenstimulated on the earlier flight.
The STL project will also test for the first time a humanhybridoma cell that has been fused and formed to make amonoclonal antibody that is the specific target of a new malariavaccine for the Army.
Because of gravity, 80 percent of energy spent in cellularactivity is to keep the cell structurally intact and oriented to itsphysical environment. Wiesmann suggested that MAbs mayincrease their rate of production in microgravity because of theincreased energy available.
"This may have great commercial value," said Wiesmann. "It'llbe remarkable if we can improve efficiency of antibodyproduction in this way."
Wiesmann told BioWorld that this will be the third attempt toproduce MAbs in space, including an effort by Genentech Inc.in the 1970s that was unsuccessful due to equipment failure,and an attempt last month by the Japanese, who havent yetpublished their results.
The STL project is "all fundamental biology at this point, whichholds a lot of promise for things we don't quite understand onearth," Weismann said.
Long-range programs of the U.S. Army include a space stationand the capability for long-term space travel. Theseexperiments could affect not only astronauts in space, buthealth care on earth as well, said Cellco's Lynn.
Three additional flights scheduled for 1993 will employ Cellcoproducts, Lynn said. The company's strategic focus is based oncellular therapy, and it is developing artificial capillary cellculture systems for delivery of cell therapy to treat cancer,genetic diseases and AIDS, and improved methods of bonemarrow transplantation.
-- Michelle Slade Associate Editor
(c) 1997 American Health Consultants. All rights reserved.