The Science Of Health: How Stem Cell Transplants For Blood Cancers Work, And What The Challenges Are

The Science Of Health: This week, on ABP Live's health column, we discuss what stem cells are, how stem cell transplants for blood cancers and disorders work, and what the challenges are.

Stem cell transplant is used to treat conditions in which the bone marrow is damaged and is no longer able to produce healthy blood cells, and can also be used to replace blood cells that have been damaged as a result of intensive cancer treatment

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The Science Of Health: Welcome back to "The Science Of Health", ABP Live's weekly health column. Last week, we discussed why some schizophrenia patients have abnormal fingerprints, and how this can be used to predict the neurodegenerative disease, and as a diagnostic marker. This week, we discuss what stem cells are, how stem cell transplants for blood cancers and disorders work, and what the challenges are. 

Stem cells are cells that can regenerate or develop into many different types of specialised cells in the body, such as muscle cells, blood cells and brain cells, serve as a repair system for the body, and can divide and renew themselves over a long time. Haematopoietic stem cell transplant, or blood stem cell transplant is the only stem-cell based treatment routinely reviewed and approved by the US Food and Drug Administration, and is used to treat patients with cancers and disorders affecting the blood and immune system. 

How stem cell transplants for different blood cancers and blood disorders work

Stem cell transplant is used to treat conditions in which the bone marrow is damaged and is no longer able to produce healthy blood cells, and can also be used to replace blood cells that have been damaged as a result of intensive cancer treatment, according to the National Health Service (NHS). Stem cells can either come from the patient's own body or from a donor. 

Stem cell transplants can treat blood cancers such as leukaemia, myeloma, and lymphoma, and blood disorders such as thalassaemia, aplastic anaemia, and sickle-cell anaemia. 

Blood cancers, also known as haematologic cancers, could be leukaemia, lymphoma and myeloma. These cancers start in the bone marrow where blood is produced, and occur when abnormal blood cells start growing out of control, and interrupt the function of normal blood cells. 

Leukaemia originates in the blood and bone marrow, lymphoma develops in the lymphatic system, and myeloma begins in the blood's plasma cells.

According to the US National Institutes of Health (NIH), stem cell transplant does not directly work against cancers, but allows the body to produce blood cells that have been destroyed due to radiation therapy or chemotherapy. 

However, there is a lack of awareness about stem cell transplants in India. 

ABP Live spoke to experts from Amrita Hospital, BLK Max Super Speciality Hospital and DKMS BMST Foundation India, and asked them about stem cell transplants, the scientific procedure, and the challenges associated with the process. 

DKMS BMST Foundation is a non-profit organisation which raises awareness about blood stem cell transplantation and registers potential blood stem cell donors. 

According to Patrick Paul, CEO of DKMS BMST Foundation India, about 80,000 donors are currently registered in the organisation's database in India, but more than two to three million donors are required. The worldwide database has about five lakh Indian donors. He said that a reason behind the number of stem cell donors being less than what the organisation expects is a lack of awareness about stem cell transplants. Also, Covid-19 proved to be a major hurdle. 

Leukaemia is the most common blood cancer in India, followed by lymphoma and myeloma. These can be treated through stem cell transplants.

The types of leukaemia most prevalent in India are chronic myeloid leukaemia and chronic lymphocytic leukaemia. 

According to the NIH, chronic myeloid leukaemia is a cancer of the blood and bone marrow in which too many myeloblasts, a type of immature blood cell that makes white blood cells called myeloid cells, are found in the blood and bone marrow, as a result of which the affected person suffers from fever, easy bleeding, anaemia, infection, bone pain and fatigue. 

Chronic lymphocytic leukaemia is a cancer of the blood and bone marrow in which excess lymphocytes, a type of white blood cell, are produced, resulting in swollen lymph nodes and fatigue.

"Myeloma is highly prevalent in India, and also the most aggressive one. Thalassaemia is the most common blood disorder in the country, and the success rate of stem cell treatment in the case of thalassaemia is more than 80 per cent. Aplastic anaemia and sickle-cell anaemia can also be treated through stem cell transplants," Dr Nitin Agarwal, HoD, Donor Request Management, DKMS BMST Foundation India, told ABP Live.  

Aplastic anaemia is a rare but serious blood condition that occurs when the stem cells in the bone marrow cannot make enough new blood cells for the body to perform functions such as infection control and oxygen transport. 

Sickle-cell anaemia is a genetic disease in which the red blood cells are sickle- or crescent-shaped.

Thalassaemia is a genetic blood disorder in which the body does not make enough haemoglobin. 

In the case of malignant or cancerous blood diseases, allogeneic bone marrow transplant, a technique in which healthy stem cells come from the bone marrow of a related donor who is not an identical twin of the patient, or from an unrelated donor who is genetically similar to the patient, is used. The graft works against the blood cancer.

"The white blood cells, which are immune cells, from the donor are inserted into the patient. These immune cells remain inside the patient's body, and fight against the cancer cells for a lifetime," Dr Pawan Kumar Singh, Associate Director, Centre For Bone Marrow Transplant, BLK Max Super Speciality Hospital, New Delhi, told ABP Live. 

He also explained that in the case of non-malignant diseases like thalassaemia and sickle-cell anaemia, the principle is to simply replace the defective blood cells with normal blood cells from the donor. 

Bone marrow, peripheral blood and cord blood are the best sources of stem cells. 

"Most stem cell transplants in the world utilise peripheral blood-derived stem cells. Certain blood cancers like myeloma and lymphoma generally require the use of the patient's own stem cells. This is called autologous stem cell transplant. Other blood cancers and disorders require stem cells derived from other individuals. These stem cells are called allogenic stem cells. Unrelated donors are anonymous volunteers who have registered themselves on donor registries throughout the world. Cord blood stem cells are usually sourced from public cord blood banks which collect and store donated cord blood after it is made to undergo extensive tests," Dr Pravas Mishra, Head, Haematology & BMT, Amrita Hospital, Faridabad, told ABP Live. 

Sometimes, siblings and parents who are only half-matched to the patient, can also donate stem cells. This process is called haploidentical stem cell transplant, Dr Mishra said.

A medicine is administered to patients to make the extraction of stem cells from the blood circulating throughout the body, or the peripheral blood, easier. This is called peripheral blood stem cell collection. 

"Earlier, about 30 years back, bone marrow was the only source of stem cells. A needle was placed inside the hip bone to bring out the stem cells. Now, a medicine is given to extract stem cells from the blood. Most of the stem cell transplant procedures are performed through peripheral blood stem cell collection," Dr Agarwal said. 

He also said that peripheral blood stem cell collection is a painless process, and there are no side effects.

Paul explained that needles are inserted into both the arms. After blood is collected from the patient, it is passed through a centrifuge to separate it from the stem cells. Then, the remaining blood is inserted back into the donor, Paul said. This process takes about three to four hours. 

So, in order to perform stem cell transplants for blood disorders, it is important to identify a suitable donor. However, if autologous transplant is performed, such as in the case of myeloma and lymphoma, a donor is not needed. This is because autologous transplant uses stem cells from the patient's own body to replace damaged blood cells, or to help the bone marrow produce healthy cells.

"After identifying a suitable donor, medical tests must be performed to determine the fitness of the donor and recipient. Then, stem cells are collected. This is followed by chemotherapy to empty the bone marrow and suppress the immunity of the recipient, and to ensure that the person's body can accept the newly introduced stem cells. After this, stem cell infusion is performed. Then, immunosuppressive drugs are given for a period of three to six months. In the case of autologous stem cell transplants, no immunosuppressive drugs are given," Dr Mishra said.

He explained that the patient must stay in the hospital for at least three to five weeks, following which they are required to visit their doctor regularly for three to four months.

The process of destroying the dysfunctional stem cells in the patient before introducing healthy stem cells into their body is called conditioning.

"Since bone marrow does not function properly in blood cancer patients, the dysfunctional stem cells must be replaced with normal stem cells from the donors. Before the stem cells are infused into the patient, they are given medications or made to undergo chemotherapy to destroy their dysfunctional stem cells. This process is called conditioning. Once the patient is conditioned, they are ready to receive new stem cells. The newly introduced stem cells enter the bone marrow. About a month or two after transfusion, the bone marrow starts producing healthy stem cells," Dr Agarwal said. 

Since the patient does not have any stem cells in the body in the month between stem cell infusion and the production of healthy stem cells following the infusion, the person is administered with red blood cells and platelets to keep the body functional.

Challenges associated with stem cell transplants

Several challenges are associated with stem cell transplants in the case of blood cancers and disorders, both for the donor and the patient. 

Infections, bleeding, regimen-related toxicity, and sinusoidal obstruction syndrome of the liver are the different potential challenges for the patient, according to Dr Singh. 

Sinusoidal obstruction syndrome is a potentially life-threatening condition characterised by abdominal pain and swelling, weight gain, hypertension, jaundice, fatigue or weakness, due to the small blood vessels leading into the liver, and those present inside the organ becoming blocked when a patient is given high doses of chemotherapy and radiation therapy before an allogeneic stem cell transplant.

Regimen-related toxicity refers to the side effects of chemotherapy, monoclonal antibody therapy and radiation to the entire body as part of conditioning prior to stem cell transfusion. 

Dr Singh explained that these challenges can reduce the efficacy of the bone marrow transplant.

“Donor challenges include providing time and effort to the process. Healthy donors are generally not considered to be at risk for adverse events. The challenges for the patient include identifying a suitable donor, high costs of the transplant and several potential life threatening complications. These include disease relapse, diseases caused in the recipient due to the graft, and graft failure and infections,” Dr Mishra said.

Paul said that the patient is very prone to death after conditioning, because the body no longer has any original stem cells. 

Dr Agarwal said it is counterintuitive that on the one hand, the patient's immune system becomes weak due to conditioning, and on the other hand, they are given immunosuppressants to ensure that the body does not reject the newly introduced stem cells.

Future projections of incidence of blood cancers in India

Citing data from the National Cancer Registry Programme, Dr Mishra said there is a possibility that the number of new cancer cases in India will increase from 1.46 million in 2022 to 1.57 million in 2025. 

He also said that of these, about 10 to 12 per cent cases among adults will be of myeloid and lymphoid malignancies. 

The incidence of myeloma, which was once considered a rare disease in India, has been increasing of late.

As experts said, it is important to raise awareness about blood cancers and disorders and about stem cell transplants so that more donors come forward, and more patients who are in need of an unrelated donor can be treated with high success rates.