Stem Cells From UCB Vs.
Bone Marrow Transplantation
Stem Cells Transplantation
Stem cell or bone marrow transplants are treatments for some types of cancer including leukemia, lymphoma, and myeloma with high dose chemotherapy and sometimes radiotherapy. They are sometimes called stem cell rescue, or bone marrow rescue, or intensive treatment.
Stem Cell Transplants in Cancer treatment
Stem cell transplants help restore blood-forming stem cells which are affected by certain cancer treatments. Stem cell transplants are procedures that restore blood-forming stem cells which are affected by the high doses of chemotherapy or radiation therapy that are used to treat certain cancers.
Blood-forming stem cells are important because they grow into different types of blood cells. The main types of blood cells are:
- White blood cells, which are part of your immune system and help your body to fight against infection
- Red blood cells, which carry oxygen throughout your body
- Platelets, which help the blood clot to stop bleeding
You need all three types of blood cells to be healthy.
Types of stem cell transplants
The blood-forming stem cells that are used in transplants can come from the bone marrow, bloodstream, or umbilical cord. Transplants can be:
- Autologous, which means the stem cells come from own, the patient
- Allogeneic, which means the stem cells come from someone else. The donor may be a blood relative but can also be not related.
- Syngeneic, which means the stem cells come from your identical twin, if you have one
To reduce possible side effects and improve the chances that an allogeneic transplant will work, the donor’s blood-forming stem cells must match in certain ways. To learn more about how blood-forming stem cells are matched, see Blood-Forming Stem Cell Transplants.
The American Academy of Paediatrics’ (AAP) policy statement (Pediatrics; 2007;119:165-170.) addresses public and private banking options available to parents. Among several recommendations, the report encourages parents to donate to public cord blood banks and discourages parents from using private cord blood banks for personal or family cord blood storage unless they have an older child with a condition that could benefit from transplantation.
Research studies of cord blood transplant outcomes, including transplants with two or more cord blood units, show promising results.
Cord Blood Stem Cell TransplantATION
The first successful cord blood stem cell transplant was performed in 1988 in Paris, France. the patient was a boy with Fanconi anemia, a genetic and potentially life-threatening type of anemia. Cord blood stem cell are used in the treatment of over 80+ critical medical conditions such as anaemia, leukaemia, bone marrow cancers, genetic and immune disorders can be treated with cord blood stem cells. to date, more than 40000 cord blood stem cell transplants from unrelated donors and several hundred from sibling donors have been performed worldwide.
Cord blood transplants can have complications similar to allogeneic stem cell transplants and should be done only at centers experienced in the transplantation of allogeneic sources of stem cells
Potential Advantages for Patients
For certain patients, there are several advantages of using donor cord blood stem cells instead of donor peripheral blood or donor marrow stem cells. Some potential advantages are
Cord blood stored in a public cord blood bank has been prescreened, tested and frozen and is ready to use; on the other hand, it can take several months to find and confirm a marrow or peripheral blood donor.
The outcomes of related and unrelated donor stem cell transplants are strongly affected by the degree of HLA matching between the transplant recipient and the donor cord blood. HLA matching plays an important role in successful engraftment, severity of graft-versus-host disease (GVHD) and overall survival. A close match between the patient and the cord blood unit can improve a patient’s outcome after transplantation. However, even though a closely matched cord blood unit is preferred, clinical studies suggest that the match may not have to be as close as the match that is necessary for bone marrow or peripheral blood transplants.
Studies have found that after a cord blood stem cell transplant, fewer patients got GVHD and, among those patients who did develop GVHD, the complication tended to be less severe than it was in patients who had bone marrow or peripheral blood transplants. GVHD is a serious and sometimes fatal complication of allogeneic stem cell transplantation. With GVHD, the donor’s immune cells (the graft) attack the patient’s healthy tissue (the host).
As a result of extending collection efforts to hospitals where births from diverse ethnic backgrounds are well represented, donated cord blood units have the potential to provide a source of stem cells that reflects racial diversity.
Cord blood stem cell transplants carry less risk of transmission of blood-borne infectious diseases compared with stem cells from the peripheral blood or marrow of related or unrelated donors.
Bone Marrow Transplantation
The soft and sponge-like substance present inside the bones is called bone marrow. It consists of immature cells known as hematopoietic or blood-forming stem cells. White blood cells, red blood cells, and platelets are the three different types of blood cells that are developed by dividing hematopoietic stem cells. The bone marrow contains the majority of hematopoietic stem cells, although some cells, known as peripheral blood stem cells (PBSCs), can be found in the bloodstream. Hematopoietic stem cells are also found in the blood of the umbilical cord. Stem Cell Transplantation can be performed using any of these sources.
A procedure known as a Bone Marrow Transplant (BMT) is performed to restore stem cells lost due to high doses of chemotherapy and/or radiation treatment.
How is bone marrow Obtained for Transplantation?
The stem cells used in BMT come from the liquid centre of the bone, called the marrow. In general, all three forms of BMTs (autologous, syngeneic, and allogeneic) go through the same “harvesting” process to collect bone marrow. Either the donor is given general anaesthesia, rendering the donor unconscious during the process, or regional anaesthesia, which results in a loss of sensation below the waist. To extract the bone’s marrow, needles are placed through the skin over the pelvic (hip) bone or, in exceptional circumstances, over the sternum (breastbone). The marrow harvesting process takes roughly an hour.
Once the bone marrow has been extracted, it is treated to remove any remaining blood and bone fragments. For the stem cells to remain viable until they are required, harvested bone marrow can be mixed with a preservative and can be frozen. Cryopreservation is the name given to this method. Stem cells can be kept frozen for several years.
How are the donor's stem cells matched?
Doctors most frequently use transplanted stem cells that closely resemble the patient’s own stem cells to reduce the risk of adverse consequences. Human leukocyte-associated (HLA) antigens are a variety of proteins that are found on the cell surfaces of different people. The HLA type, a group of proteins, is determined by a specific blood test. The likelihood that the patient’s body will accept the donor stem cells increases with the number of HLA antigens that match. Siblings have a 25% probability of being a complete match. From an unrelated donor, there is a marginally better chance of receiving stem cells that are HLA-matched, with about 50% of the same ethnic and racial background.
How To Find Matching Donor Stem Cells?
HLA typing is used to find a matching donor for stem cell transplant.
What is HLA?
Human Leukocyte Antigen are special proteins that form HLA Markers. These markers help the immune system identify which cells belong to you. The most successful transplants happen when the patient’s HLA and donor’s HLA closely match.
HLA Matching
- A test like a blood grouping test but much more complex
- Immediate family is the first source of donors as HLA markers are inherited from parents
- 4 out of 6 HLA match (~67%) between the patient & the donor is sufficient for cord blood stem cell transplant
Challenges Of Finding A Matching Donor In Our Own Family
- ½ of your HLA markers are inherited from father and ½ from mother, so a match is difficult for any of the parents
- Siblings have 25%chance of being a full match.
- 70%of Indian patients DO NOT find a match in their family
Risks associated with donating bone marrow
The risk associated here is similar to that of undergoing a surgery. The use of anaesthetic during the process poses the great risk with respect to bone marrow donation.
The area where the bone marrow was removed may remain stiff or uncomfortable for a few days and the donor may feel worn out. The donor’s body replaces the donated marrow within few weeks, however, the recovery period for each donor may vary. While some people can resume their regular activities in five to seven days, others may need four to six weeks to fully recover their strength.
