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Bone marrow transplant

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Microscopic veiw of bone marrow cells

Bone marrow is the soft, spongy tissue found in the center of bones.[1] It is where blood cells are formed.[2] A bone marrow transplant may be necessary to fight against diseases, such as caner or leukemia.[3] There are three forms of transplants: autologous, allogeneic, and umbilical cord transplants. Although transplants can completely eradicate diseases, they are not without risks of their own.[1] Graft-Versus-Host-Disease is a common complication that can occur, and can range from mild to life-threatening in severity.[4]

What is Bone Marrow/ a Bone Marrow Transplant?

Graphic identifying the sections of bone marrow.

Before delving into bone marrow transplants, it is important to understand what bone marrow is, and why it is so vital to the human body. Bone marrow is the soft, spongy tissue found inside the bones.[1] This marrow contains immature cells, often called stem cells.[3] These stem cells are blood-forming, meaning they can grow into red blood cells, which carry oxygen throughout the body, white blood cells, which fight infections, or platelets, which help to control bleeding through coagulation. Both healthy marrow and the blood cells are necessary to live. When a disease affects the marrow’s effectiveness, bone marrow transplant is often the best treatment option and, in some cases, the only option available.[2]

A bone marrow transplant replaces a person’s unhealthy or missing bone marrow. The marrow is replaced with healthy marrow stem cells from a donor. Reasons for replacing marrow include either the marrow not working properly or has been destroyed by chemotherapy or radiation.[1] Once the marrow is destroyed, a patient’s body can no longer produce blood cells. [5] It’s believed that in many cancers, once the transplant is complete, the white blood cells from the donor will attack any remaining cancer cells in the recipient's body, much like they would an infection.[1] These transplants are used to treat diseases including leukemia, sickle cell anemia, and multiple myeloma, as well as certain immune deficiency disorders and other severe blood diseases (such as thalassemias and aplastic anemia).[3] Bone marrow transplants allow doctors to administer extremely high doses of chemotherapy. This is extremely beneficial when trying to cure certain types of cancer, such as lymphoma. Because higher doses of chemotherapy can be administered, there is a chance that these patients are more likely to survive their cancer than with other forms of treatment.[5]


There are three types of bone marrow transplants: autologous, allogeneic, and umbilical cord transplants. In an autologous (meaning ‘self’) transplant, also known as a rescue transplant, the patient’s own stem cells are removed before receiving chemotherapy. The cells are stored in a freezer until the chemotherapy treatment is complete. Upon completion, the stem cells are returned to the individual’s body to resume producing blood cells. In an allogeneic (meaning ‘other’) transplant, stem cells are removed from a donor. In nearly every case, the donor’s genes must at least partially match the recipient's own genes. Very specific tests designed to select the best donor-recipient match are performed before the transplant begins. Siblings of the recipient often present good matches. Parents, children, or other relatives, while not as often, also hold the possibility of matching. If no familiar matches can be found, donors not related to the individual, but who still match his genetic makeup enough for the body to accept the transplant, can also be found through bone marrow registries. Finally, there are umbilical cord transplants, which are a branch of allogeneic transplants. In this form of transplantation, stem cells are removed from the umbilical cord of a newborn baby immediately following their birth. The stem cells are frozen until needed. These cells are less developed, so the need for perfect genetic matches is reduced.[1] Despite the benefits of bone marrow transplants, the procedure is not without risks, some life-threatening. Nevertheless, for some individuals, marrow transplant is the best chance for surviving.[3] Because of increased research in the area of marrow transplantation, survival rates have shown improvement.[6]

Process

A transplant bag full of donor bone marrow.

Before the transplant occurs, chemotherapy or radiation treatment is administered.[1] The purpose of these treatments is to destroy the unhealthy stem cells in the patient’s marrow, as well as to suppress their immune system in order to keep it from attacking the new stem cells transplanted in. [3] This can occur in one of two ways. The first, an ablative treatment, as mentioned before, involves a high-dose treatment to kill any cancer cells. In the process, any healthy bone marrow is also killed. This allows new stem cells to grow following the transplant. The second form is known as reduced intensity treatment, or a mini transplant. As the name denotes, a smaller dosage of chemo or radiation is administered, which allows both older patients and patients suffering from other health issues to receive a bone marrow transplant as well.[1]

The way in which the donor marrow is collected varies as well. The first method, bone marrow harvest, entails a minor surgery performed under general anesthesia. In this pain-free procedure, the marrow is removed from the back of both hip bones. The amount removed depends on the weight of the recipient. The other form is known as leukapheresis. This entails several days of shot administered in order to stimulate the donor’s stem cells into moving from the marrow into the blood. The blood is then removed through an IV line. The stem cells are isolated from the rest of the blood in a machine to be given to the recepient and the remaining blood is returned to the donor.[1]

During the actual transplant, the stem cells are delivered into the recipient’s bloodstream through a central venous catheter, similar to a blood transfusion.[1] The new cells find their way back to the bones, and, if the transplant is successful, the recipient will once again make the blood cells they need. This is often referred to as bone marrow rescue, because the marrow is returned in order to “rescue” the patient from the effects of the chemotherapy or radiation.[5] In the majority of transplants, no surgery is needed.[1]

Risks vs. Benefits

Bone marrow being harvested from a donor.

Following a bone marrow transplant, several symptoms can occur, including chest pain, fever, chills, flushing, a drop in blood pressure, headaches, hives, nausea, pain, and shortness of breath. In addition to this, there is the possibility for complications, such as anemia, blood in the lungs and other areas in the body, blood clotting, liver, heart, lung, or kidney damage, Graft-Versus-Host-Disease, or delayed growth in child recipients. In severe cases, complications could lead to death. These potential complications depend on several variables, including the disease being treated, age, overall health, and the closeness of the donor match.[1]

However, despite these risks, a successful transplant can partially or completely cure the disease being treated for. If the transplant succeeds, a normal life is achievable as soon as the recipient feels healthy. This usually takes about a year to recover fully, depending on complications experienced. [1]

Graft Vs. Host Disease

Graphic describing the stages of Graft Versus Host Disease immuno-biology.

Graft-Versus-Host-Disease, also known as GVHD, is a common side effect of allogeneic transplants. GVHD affects many parts of the body, including the eyes, skin, mouth, stomach, and intestines. The disease occurs because the donated cells are genetically different from the recipient’s, causing the recipient's immune system to potentially reject their differences and attack them. Two forms of GVHD exist: acute and chronic. Acute GVHD usually develops in the first 100 days following the transplant, but can develop later on. This form mainly attacks the skin, stomach, intestines, and liver. Chronic GVHD, conversely, develops 3 to 6 months after the transplant,[4]and generally affect the joints, eyes, mouth, and skin.[7] Signs of this form can surface sooner than this, and if acute GVHD occurs, the recipient is more likely to contract chronic GVHD. The severity of either form can range anywhere from mild to life-threatening. In many cases, doctors view mild forms of GVHD as beneficial if the transplant was for blood cancer, because it shows that the recipient’s immune system is still fighting, trying to destroy any remaining cancer cells. If the recipient experiences GVHD, they have a lower risk of relapsing than those who do not suffer from it. However, in cases when the transplant was to treat things such as aplastic anemia, doctors are likely to treat even mild forms of GVHD.[4]


Most recipients will experience GVHD to some degree. However, steps can be taken to reduce the risk of it developing. Nevertheless, there are still times when it will develop regardless of steps taken. Ways to minimize the amount of complications experienced include taking all medications prescribed, regardless of “feeling better,” protecting oneself against the sun’s UV rays, and watching for warning signs of GVHD, as early detection can reduce the severity.[8] These signs, generally taught about by a doctor before or following the transplant, differ between acute and chronic GVHD. For acute GVHD, the skin develops faint to severe sunburn-like rashes and blisters; constant nausea develops, as well as a reduced appetite and vomiting; diarrhea and abdominal discomfort, bloating and blood in the stool can be present; jaundice may develop, as well as dark urine and water weight gain. In chronic GVHD, warning signs include a change in skin texture or nails, rashes, arthritis-like symptoms, pain or stiffness in joints, dry eyes, blurred vision or persistent irritation, stiff mouth (trouble opening), sores or pain, a cough that does not resolve, shortness of breath or difficulty breathing, pain during intercourse, dryness, or irritation in the genitals.[7]


GVHD is potentially very serious, but several treatments are available. It is important to start treatment as early as possible for the best results in treating the disease. The main treatment is to prescribe medication (immunosuppressants) that will weaken the donor’s immune system, and are received during the transplant. Side effects from immunosuppressants include an increased risk of infection.[9] In some cases of transplants, a doctor may decide to use a half-matched transplant (known as a haploidentical transplant). This means the donor is at a minimum a 50% match to the recipient. These are most commonly from a sibling, parent, or child. These are often difficult to perform because of such an increased risk of infection and severe GVHD. Recipients of this form of transplant are much more likely to suffer from GVHD. However, doctors are improving this form of transplant, reducing risks and making it more likely to become a common transplant option.[5]

Video

Successful Bone Marrow Transplant story.

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Bone Marrow Transplant U.S. National Library of Medicine. Web. Updated January 27, 2015. Unknown Author.
  2. 2.0 2.1 How a bone marrow transplant works Be the Match. Web. Accessed April 18, 2016.Author Unknown.
  3. 3.0 3.1 3.2 3.3 3.4 Bone Marrow Transplantation U.S. National Library of Medicine. Web. Updated April 20, 2016. Unknown Author
  4. 4.0 4.1 4.2 Graft-versus-host-disease Be The Match. Web. Accessed April 18, 2016. Author unlisted.
  5. 5.0 5.1 5.2 5.3 Bone Marrow Transplants Cancer Research UK. Web. Updated March 16, 2015. Author Unknown.
  6. What is a bone marrow transplant? Be the Match. Web. Accessed April 18, 2016. Unknown Author.
  7. 7.0 7.1 GVHD Treatment Be The Match. Web. Accessed April 18, 2016. Unknown Author.
  8. GVHD Prevention Be The Match. Web. Accessed April 18, 2016. Unknown Author.
  9. GVHD Treatment Be The Match. Web. Accessed April 18, 2016. Unknown Author.