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  Anemia & Blood Diseases

January 2010
Stem Cell Transplant in Blood Disorders
Dr Chirag A. Shah
 
Stem cell transplant is the exciting cutting edge of medicine, a topic of hot debate, and a new beginning in treatment modalities that you could consider!

Though research is continuing in several areas, stem cell transplant is already an established treatment in the field of blood disorders or hematology, like leukemia, lymphoma, myeloma, thalassemia etc. While around 30,000 stem cell transplants are performed in Europe yearly, only about 300 are done in India every year. The need in our country meanwhile, is at least 50,000 transplants per year, to quote a very conservative figure. Though in India, a stem cell transplant would cost only one-tenth of what the same treatment would cost in western countries, people still flock abroad for the lack of good centres here. Becoming aware of this treatment option and the best centres for it, would certainly be beneficial.

Demystifying Stem Cells
Stem cell or the 'basic cell' is a simple concept, based on the fact that all humans are made from a single cell. This cell gives rise to all body tissues and organs. However, it has been found that even in adult body, there are cells which can differentiate into any type of cell, and hence potentially can recreate any tissue! This is the premise of stem cell research. If we can find these cells and understand their controls, we can recreate and replace injured or lost tissues due to heart attack, stroke/ paralysis, diabetes, arthritis, liver or kidney damage, etc.

However, it is not as easy as it sounds. Till now, we have not be able to achieve the amount of control that we would like to have - when we inject stem cells into an area of the heart, we still can't predict whether they will grow into heart muscle cells or nerve cells or blood vessel wall cells or in what proportion. Thus, except for haematology, applications of stem cell research in all other diseases are still only in experimental stages.

Stem Cell for Blood Cancer
Consider the case of 29-year-old Pavan*, the only son of his aged parents. A software engineer, Pavan got married three years ago, and has a beautiful daughter now. His wife is pregnant again, and everyone home was eagerly awaiting the latest addition to the family. That is when Pavan was diagnosed to have acute myeloid leukemia, a type of blood cancer. The white cells in his body shot up to 1,80,000 (normal count should be within 4000 to 10,000). Pavan had to be put in remission with standard therapy. The doctors warned that the risk of recurrence was high. Pavan's family wanted to increase the chances of cure as much as possible, with reasonably safe and proven methods. The young father was thus made to undergo high dose chemotherapy followed by stem cell transplant. From his earlier hopeless position, Pavan now had about 50 percent chance of being cured! He can't wait to see his second daughter now.

3 Purposes of Stem Cell Treatment
  1. Supportive therapy: Very high doses of chemotherapy ablate the bone marrow. Without stem cell support, it will take the marrow a very long time to recover, resulting in high death rate from infection or bleeding. Infused stem cells provide early recovery of blood cells, cutting down such risks. Thus it is a form of supportive therapy and not a treatment of cancer by itself. This is the case in autologus transplants (collecting stem cells from one's own body).
  2. Graft versus disease activity: In cases of chronic myeloid leukemia where hematological malignancy is highly evident, allogeneic stem cell transplants (collecting stem cells from someone else's body) are done.
  3. Replacing a missing gene: In thalassemia, sickle cell disease, and various other genetic disorders where a person is normal, except for one missing gene, stem cell therapy helps – by curatively replacing that gene.
Stem cell transplant in hematology requires no surgery, unlike a kidney or liver transplant. Though the patient is kept in his room throughout the hospitalization to reduce infections, he is otherwise reasonably well - talking, eating, taking walks every day.

Collecting Stem Cells
Hematopoietic stem cells live in the bone marrow, peripheral blood and cord blood – but they constitute less than 1 in 1,00,000 bone marrow cells. Dr. Chirag A. Shah is Oncologist and Hematologist at Apollo Hospitals, Ahmedabad These cells are capable of self renewal as well as producing progenitor cells which differentiate into mature blood cells. Since they are very few in numbers, bone marrow is stimulated with use of growth factors with or without help of chemotherapy. Collection is done using a procedure called apheresis, almost similar to the dialysis done for patients with kidney failure. Then they can be collected from either bone marrow or peripheral blood. The procedure is nearly risk free.

Also, there is no permanent loss from the body as stem cells are recovered in a few days time. Because of such safety of this procedure, and because this is such a life saving treatment, over 15 lakh people have registered themselves as voluntary donors in USA alone, in a national registry. Unfortunately, there is no such registry in India (though cord blood registries are coming up).

Storing Stem Cells
Stem cells are stored at very low temperatures (minus 800C or in liquid nitrogen) after special chemicals are added, to maintain their viability for a long time. When needed, the bag full of stem cells and additive liquids is thawed and transfused with some specific precautions (almost like a blood transfusion).

Risks
Stem cell transplants are done with high doses of chemotherapy and other highly immunosuppressive agents entailing risks of the same, as well as risks of graft versus host disease. Most common risks are related to infection, bleeding, chemotherapy related organ injury (kidney, liver, lungs, etc) and graft versus host disease. However the mortality rate of transplant has reduced significantly, and is now in the range of five to 10 percent for autologus transplants and about 10 to 30 percent for allogeneic transplants.

Cost
Cost of this treatment is mainly related to the use of blood products, antibiotics/ antifungals etc, isolation unit, specially trained staff, chemotherapy/ immunosuppressive agents, investigations, stem cell collection and storage. The final figure usually features between five lakhs (for autologus) to10 lakhs (for allogeneic).

Indian Perspective
In India patients we get to see are comparatively younger - almost by a decade – than in the West. Which also means that they can tolerate aggressive treatments like transplants much better. The stem cell treatment per se does not cure lymphoma, but it adds about a 15 percent increase in absolute survival when used upfront with chemotherapy. Also, autologus transplants can cure much higher number of relapsed lymphomas. Thalassemia major has a very good cure rate with transplant, and we have a very high number in India, especially in Gujarat. Research in stem cell technology is likely to further improve safety profile of these therapies, and also reduce cost.
 
Dr.Chirag A. Shah is Oncologist and Hematologist at Apollo Hospitals, Ahmedabad

 


    
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