What are stem cells?

Stem cells are unspecialized cells characterized by two special properties:

• Self-renewal – The ability to divide itself into exact copies numerous times, without changing into specific cell types
• Potency – The capacity to differentiate into specialized cell types (heart, brain, blood).

Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.

How are stem cells different from other cells

Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues. In other organs, however, such as the pancreas and the heart, stem cells only divide under special conditions.

Why are stem cells important?

Given their unique regenerative abilities, stem cells offer new potentials for treating diseases such as diabetes, heart disease, and liver disease. However, much work remains to be done in the laboratory and the clinic to understand how to use these cells for cell-based therapies to treat disease, which is also referred to as regenerative or reparative medicine.

What goes wrong in chronic liver disease?

In chronic liver disease (also called cirrhosis), a lot of liver damage happens over a long period of time. The normal repair processes are impaired and scars are formed in the liver. The only currently available treatment for patients with chronic liver disease is an organ transplant. Transplants are expensive and there are not enough organ donors to treat all the patients. Alternative therapies must therefore be found for patients with liver cirrhosis.

Can stem cell therapies work for liver disease?

In the long term, stem cells might provide new ways to treat chronic liver disease:

• Researchers are working to identify liver stem cells more precisely, and to understand how they could be used to treat patients.
• Embryonic stem cells or induced pluripotent stem cells might be used to make new hepatocytes in the laboratory for patients whose liver can no longer regenerate.

However, there are still a number of fundamental questions that must be answered before this kind of treatment can be developed. For example, it will be important to find out which molecular cues are required by stem cells to make hepatocytes.

Can we use bone marrow cells to treat chronic liver disease?

Another route to new treatments might be to use cells made from a patient’s own bone marrow to help repair damaged liver tissue. These cells are called hematopoetic stem cells. Under normal circumstances, hematopoetic stem cells can generate blood cells, however, when need arises these same hematopoetic stem cells can go into the liver and generate liver cells.

How are hematopoetic stem cells stimulated for treatment of chronic liver disease?

Various growth factors are given which specifically stimulate hematopoetic stem cells to rapidly multiply. These stem cells then circulate in blood and some of them reach and home into the diseased liver. Once in the liver these stem cells by process of trans-differentiation transform into liver stem cells and start multiplying into liver cells. Thus liver regenerates by help of these bone-marrow derived hematopoetic stem cells which have homed into the liver.

Is this therapy proven to help in liver disease?

Yes. In a landmark study published recently it was shown that patients of acute-on-chronic liver failure, who received this kind of therapy by had significantly better survival than those who were not given such therapy. In another study published from Sir Ganga Ram Hospital it was shown that this kind of therapy gave significant improvement to the liver function tests.

What benefit can be expected with this therapy?

It has been observed that with use of this therapy the patients liver parameters significantly improve, and this improvement can last upto 6 months. After 6 months the therapy can be repeated to expect further benefit.

Can stem cell therapy be used in place of liver transplantation?

No. Stem cell therapy cannot replace liver transplantation, which is the ultimate therapy for liver failure. However, stem cell therapy can be used as a bridge to liver transplantation. Thus these patients can gain few months till their liver transplantation be arranged.