To understand what is allogeneic stem cell transplant, one first needs to know what is a stem cell and what exactly a stem cell transplant is.
Stem cells are special types of cells found in our body that has the ability to later develop into various types of cells, starting from brain cells and muscle cells to blood cells. It is these stem cells from which all the cells in our body with specialized functions are developed.
There are different types of stem cells. Depending on the types of cells it can later differentiate into, stem cells are classified into mainly five types. These are known as totipotent, pluripotent, multipotent, oligopotent and unipotent cells.
Hematopoietic stem cell transplant(HSCT)
It is also known as a stem cell transplant or a bone marrow transplant. Multipotent Hematopoietic stem cells are used for this procedure. These are cells that later transform into blood cells.
Bone marrow is a type of spongy, soft tissue that is found in the center of most bones. It contains hematopoietic stem cells. Hematopoietic stem cells are also found in peripheral blood that moves through our bodies.
In hematopoietic stem cell transplant, damaged hematopoietic stem cells are removed and healthy cells are transplanted.
Hematopoietic stem cells(HSCT) can be destroyed by both cancer and cancer treatment, such as chemo and radiation. That is why HSCT is used after cancer treatment. But sometimes it is also used for other benign conditions.
When hematopoietic stem cells are damaged, they will not be able to transform into blood cells such as red blood cells, white blood cells, or platelets. So through this transplantation, those damaged cells are replaced with healthy cells.
The FDA(Food or Drug Administration) has approved HSCT for the treatment of certain types of cancers, some blood disorders, and certain autoimmune disorders.
Some disease for which HSCT is approved includes
- Thalassemia
- Leukemia
- Sickle-cell disease
- Some Lymphoma
- Some Myeloma
- Aplastic Anaemia
E. Donnell Thomas, performed HSCT for the first time as a new form of cancer therapy, back in 1957. Although initially, it was not much successful, later it evolved to become one important procedure for cancer and many other diseases.
Allogeneic vs Autologous stem cell transplant
Allogeneic stem cell transplant: Bone marrow stem cell transplant or hematopoietic stem cell transplant can be divided mainly into two types. The first one is called an allogeneic stem cell transplant. It is also known as an ALLO transplant.
In an allogeneic transplant, required stem cells are obtained either from a family member or an unrelated donor. Cells are extracted either from the bone marrow, peripheral blood, or umbilical cord blood of the donor.
So, how is allogeneic transplant done?
At first, healthy stem cell from the donor is collected. The patient then receives chemotherapy or a combination of chemotherapy or radiotherapy. After that, healthy stem cells that are collected from the donor are transplanted into the patient’s body.
Different types of allogeneic stem cell transplant
There are mainly two types of preparative regimens that could be given before an allogeneic stem cell transplant. Depending on the regimen, allogeneic stem cell transplant is also classified into two categories
- The first one is known as the standard intensity regimen. Here very high doses of chemo, with or without high doses of radiation is used. It is also known as a myeloablative stem cell transplant.
- The second one is known as a reduced-intensity regimen. Here a much lower dose of chemotherapy is used, with or without a low dose of radiation. It is known as a non-myeloablative stem cell transplant.
Autologous stem cell transplant
In an autologous stem cell transplant, there is no donor. Stem cells needed are collected from the patient himself(or herself), preserved, and later reinfused into the body of the patient. It is also known as an AUTO transplant.
Is autologous or allogeneic more effective?
It depends on the conditions you have. Your doctor will decide which one should you go after. Also, there is a chance of infection with graft-versus-host-disease, in allogeneic stem cell transplant. This happens when the donor’s stem cells view the recipient’s body as a foreign object and attack its tissues. On the other hand, in an autologous transplant, as the cells collected are from the patient’s own body, the chances of graft-versus-host-disease is very low. And there will not be any rejection of transplanted cells.
Future of stem cell therapy
Stem cell research has become one of the most promising areas in modern medicine. Therapies for many diseases will be developed in the future from stem cell technology. A lot of research is going on in the field of stem cell treatment. In the future, HSCT and other stem cell therapies might be used in the treatment of many other diseases. It might also be used in neurodegenerative diseases like Alzheimer’s and Parkinson’s. Mesenchymal stem cell therapy
A lot of research is being done to transform stem cells into specific cell types(such as blood cells, neurons, and liver cells) in laboratory settings. So when we are able to develop stem cells into specific cell types, we will be able to cure specific diseases by injecting those cells into the patient’s body. For example, we can inject cardiac cells in patients suffering from Myocardial Infarction, neurons in a stroke patient, and even skin cells in patients with serious wounds. Many researchers around the world have already succeeded in turning stem cells into specialized cells or tissues, even mini organs.