From outer space to "inner space" A scientific breakthrough discovered in outer space may soon help combat diseases on terra firma
By Carisa Paraz, MD, Contributing Writer
At a research forum organized by the University of the Philippines-National Institutes of Health, Dr. Raul Destura shared updates on his study involving tissue-culture technology that could have exciting implications. The study focused on developing a tissue culture for Cryptosporidium parvum, a protozoan that is thought to cause diarrhea only in immunocompromised individuals such as those with HIV/AIDS or who are undergoing chemotherapy. However, Destura explained that new studies showed that cryptosporidial infection could be responsible for diarrhea and malnutrition among children. "We were looking at vaccine development for cryptosporidium infection because studies have shown that this is a potential bio-weapon because you only need five oocysts to develop the disease," said Destura. Cryptosporidium has been identified as a bioweapon because of its inherent survival capabilities. Its thick oocyst prevents it from being killed with chlorination or application of 100-percent bleach. Moreover, its unusual mode of infecting an organism makes it a difficult target for drugs. He explained: "Cryptosporidium is intracellular but extracytoplasmic so [they're outside the] cytoplasm [but inside] the cell wall, and because of that there are no drugs available in the market that can actually kill this organism except your immune system." Scientists have also experienced difficulty with in vitro and in vivo models of crypto-sporidial infection. Several animal studies using mice, ferrets and calves have failed to produce satisfying results. Fortunately, tissue technologists during a NASA space flight discovered that growing cells in a zero-gravity environment resulted in their differentiating into cells that approximated the organs where they came from. They identified that the low-shear stress and low-turbulence environment of outer space is similar to the environment in utero, thus the response of the cells. This environment was duplicated on earth in what is called a "rotating wall vessel culture apparatus." Destura and colleagues used this machine to culture HCT8 (human colon adenocarcinoma) cells which are similar to human intestinal tissue. Cells that grew in this culture developed characteristics that are only seen in cross-sections of intestinal epithelium, such as tight junction proteins. This does not happen with intestinal-cell cultures grown in a monolayer (like a Petri dish, for example). They were able to successfully infect the cells with cryptosporidium. They noted cellular disarray and destruction of cells. The team also developed a form of immunola-beling cryptosporidium, thus enabling them to verify the presence of the protozoan in the culture. For developing the first model for protozoan infection in the world, the study was given the award for scientific breakthroughs when it was presented at the 2006 meeting of the Infectious Diseases Society of America held in Toronto. Things are looking up for humans but not for protozoans. They are now looking at studies involving other protozoans such as amoeba, as well as other targets that can be used to validate drugs that may be tested on humans later on. M |
