New Research brings Hope to Liver Disease Patients
The liver processes nutrients from food, makes bile, removes toxins from the body and builds proteins, all of which are essential to the normal, healthy functioning of the body. Any injury, be it by trauma or by disease, to the liver is very concerning. Liver disease ranks among the leading causes for adult death in the United States. The American Liver Foundation estimates that over 20,000 Americans die from liver disease each year. In most cases of advanced liver disease an organ transplant is necessary if the patient is to live. Unfortunately the wait for a matching donor liver can be very long and many patients die waiting. New research conducted at The Medical College of Wisconsin in Milwaukee(Karim Si-Tayeb et al 2009), however, provides hope for an alternative.
Basic Biology: Every organ in our body is composed of cells. All of the cells within an organ work together and have special characteristics that allow them to carry out the work of each specific organ. Lungs tissue cells are not the same as kidney cells and kidney cells are not the same as liver cells. Specialized organ cells are not interchangeable, which is why the kidneys, say, cannot do the job of the liver. Stem cells are a different matter. Early in development all of our specialized cells originate from general, nonspecific cells called stem cells. Stem cells have the remarkable ability to generate any kind of specialized cell that the body needs. They are the shape-shifters of the cellular world. The discovery of this pliable nature has generated a lot of excitement in various fields of research but there have been complications and ethical issues. Two types of stem cells exist: embryonic stem cells (like those found in newly conceived life) and adult stem cells. Most stem cell research has focused on embryonic stems cells because adult tissue has fewer useable stem cells in each sample and these cells do not divide and reproduced as quickly or in as great a number as do the embryonic cells. These limitations make obtaining enough cells for research difficult. The problem is, however, that embryonic stem cells were originally obtained through the abortion of a live fetus which raises enormous ethical and moral implications. Newer research has begun to look at ways to make use of adult stem cells.
The Research and its Implications: The research built on a previously published study in which adult skin cells were manipulated into behaving like embryonic stem cells. These newly reprogrammed cells have many of the same properties as pluripotent stem cells, the kind of stem cell that can most easily become any other kind of cell. Pluripotent stem cells have the ability to differentiate into any of the over 200 different types of cells in the human body. The new research focused on tricking these lab-created stem cells into forming liver cells. The lab methods mirrored, step by step, the natural process that changes stem cells to liver cells during embryonic development. The careful methods resulted in an abundance of relatively pure, functional liver cells. The hope, then, is that eventually these healthy lab-created liver cells can be transplanted into a patient and supplement or replace a failing human liver thereby eliminating the need for donor livers and saving lives in the process. The research is still new and there are a lot of steps to take yet before these cells can replace liver transplants but the results are very promising and offer hope to people suffering from liver disease.
Citation: Karim Si-Tayeb, Fallon K. Noto, Masato Nagaoka, Jixuan Li, Michele A. Battle, Christine Duris, Paula E. North, Stephen Dalton, Stephen A. Duncan. Highly efficient generation of human hepatocyte-like cells from induced pluripotent stem cells. Hepatology, 2009; NA DOI: