- Bioartificial liver device
A bioartificial liver device (BAL) is an artificial
extracorporeal supportive device for an individual who is suffering fromacute liver failure .Use
The purpose of BAL-type devices, currently, is not to permanently replace
liver function s, but to serve as a supportive device, [cite journal |author=Allen J, Hassanein T, Bhatia S |title=Advances in bioartificial liver devices |journal=Hepatology |volume=34 |issue=3 |pages=447–55 |year=2001 |pmid=11526528 |doi=10.1053/jhep.2001.26753 [http://lmrt.mit.edu/publications/Advances_in_Bioartificial_Liver_Devices.pdf Free Full Text] .] either allowing the liver to regenerate properly uponacute liver failure , or to bridge the individual's liver functions until a transplant is possible.Function
BALs are essentially
bioreactor s, with embeddedhepatocytes (liver cells) that perform the functions of a normalliver . They process oxygenatedblood plasma , which is separated from the otherblood constituents. [cite journal |author=Strain A, Neuberger J |title=A bioartificial liver--state of the art |journal=Science |volume=295 |issue=5557 |pages=1005–9 |year=2002 |pmid=11834813 |doi=10.1126/science.1068660] Several types of BALs are being developed, including hollow fiber systems and flat membrane sheet systems. [ [http://biomed.brown.edu/Courses/BI108/BI108_2002_Groups/liver/webpage/Current_Work.htm Current Work on the Bioartificial Liver] ]Hollow fiber system
One type of BAL is similar to
kidney dialysis systems that employ a hollow fiber cartridge. Hepatocytes are suspended in a gel solution, such ascollagen , which is injected into a series of hollow fibers. In the case of collagen, the suspension is then gelled within the fibers, usually by a temperature change. The hepatocytes then contract the gel by their attachment to the collagen matrix, reducing the volume of the suspension and creating a flow space within the fibers. Nutrient media is circulated through the fibers to sustain the cells. During use, a patient's blood is fed into the space surrounding the fibers. The fibers, which are composed of a semi-permeable membrane, facilitate transfer of toxins, nutrients and other chemicals between the blood and the suspended cells. The membrane also keeps immune bodies, such asimmunoglobulin s, from passing to the cells to prevent an immune system rejection. [ [http://hugroup.cems.umn.edu/Research/bal/BAL-howitworks.htm University of Minnesota Bioartificial Liver: How it Works] ]Comparison to liver dialysis
The advantages of using a BAL, over other dialysis-type devices (e.g.
liver dialysis ), is thatmetabolic functions (such aslipid and plasmalipoprotein synthesis, regulation ofcarbohydrate homeostasis , production of serum albumin andclotting factor s, etc.), in addition todetoxification , can be replicated without the use of multiple devices. There are currently several BAL devices currently in clinical trials.A series of studies in 2004 showed that a BAL device reduced mortality by about half in acute liver failure cases [ [http://www.innovations-report.de/html/berichte/medizin_gesundheit/bericht-28316.html Major study: Bioartificial liver reduces mortality by 44 percent in acute liver-failure patients] ] . The studies, which covered 171 patients in the U.S. and Europe, compared standard supportive care to the use of a bioreactor device using pig liver cells.
ee also
*
Artificial extracorporeal liver support
*Liver dialysis
*Tissue engineering References
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