What Is Bone Marrow Transplant? – Indications, Procedure

What Is Bone Marrow Transplant?/Bone Marrow Transplant (hematopoietic stem cell transplant) (HPSCT) involves the administration of healthy hematopoietic stem cells in patients with dysfunctional or depleted bone marrow. This helps to augment bone marrow function and allows, depending on the disease being treated, to either destroy tumor cells with malignancy or to generate functional cells that can replace the dysfunctional ones in cases like immune deficiency syndromes, hemoglobinopathies, and other diseases.

Hematopoietic stem cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood. It may be autologous (the patient’s own stem cells are used), allogeneic (the stem cells come from a donor), or syngeneic (from an identical twin).^[rx][rx] It is most often performed for patients with certain cancers of the blood or bone marrow, such as multiple myeloma or leukemia.^[rx] In these cases, the recipient’s immune system is usually destroyed with radiation or chemotherapy before the transplantation. Infection and graft-versus-host disease are major complications of allogeneic HSCT.^[rx]

Types of Bone Marrow Transplant

There are two major types of bone marrow transplants. The type used will depend on the reason you need a transplant.

Autologous Transplants

• Autologous transplants involve the use of a person’s own stem cells. They typically involve harvesting your cells before beginning a damaging therapy to cells like chemotherapy or radiation. After the treatment is done, your own cells are returned to your body.
• Stem cells are removed from you before you receive high-dose chemotherapy or radiation treatment. The stem cells are stored in a freezer. After high-dose chemotherapy or radiation treatments, your stems cells are put back in your body to make normal blood cells. This is called a rescue transplant.
• This type of transplant isn’t always available. It can only be used if you have healthy bone marrow. However, it reduces the risk of some serious complications, including GVHD.

Allogeneic Transplants

• The term allo means other. Stem cells are removed from another person, called a donor. Most times, the donor’s genes must at least partly match your genes. Special tests are done to see if a donor is a good match for you. A brother or sister is most likely to be a good match. Sometimes parents, children, and other relatives are good matches. Donors who are not related to you, yet still match, may be found through national bone marrow registries.
• Allogeneic transplants are necessary if you have a condition that has damaged your bone marrow cells. However, they have a higher risk of certain complications, such as GVHD. You’ll also probably need to be put onmedications to suppress your immune system so that your body doesn’t attack the new cells. This can leave you susceptible to illness.
  • Related donor transplant — Typically patients begin by trying to identify a relative to be their donor. Siblings are most likely to be a close match (based on HLA typing).
  • Matched unrelated donor transplant — If you don’t have a relative available who is a match, doctors can search international donor registries for an unrelated donor.
  • Haploidentical transplant — If you have not been able to find a closely matched donor, you may be able to receive stem cells from a donor who is a half-match for you. This option broadens the pool of potential donors. Haploidentical, or half-matched, transplants rely on advances in drug therapies to prevent graft-versus-host disease.
  • Cord blood transplant — Stem cells from donated cord blood don’t need to match you as closely. The immune cells in cord blood are not yet trained to fight foreign invaders, like bacteria, so they’re less likely to interact adversely with your tissues. Normally, a unit of cord blood doesn’t have enough stem cells for a transplant in an adult. But doctors can combine units of cord blood and also greatly expand the number of cells per unit using specialized techniques in the lab.

Umbilical cord blood transplant

• This is a type of allogeneic transplant. Stem cells are removed from a newborn baby’s umbilical cord right after birth. The stem cells are frozen and stored until they are needed for a transplant. Umbilical cord blood cells are very immature so there is less of a need for perfect matching. Due to the smaller number of stem cells, blood counts take much longer to recover.

Syngeneic (identical twin transplant)

• Stem cells are donated by an identical twin, which is an ideal donor because of the matching genetic identity between donor and recipient.

Parent-child transplant and haplotype mismatched transplant

• Cells from a parent, child, brother, or sister are not always a perfect match for a patient’s HLA type, but they are a 50% match. Doctors are using these types of transplants more often, to expand the use of transplantation as an effective cancer treatment.

Before the transplant, chemotherapy, radiation, or both may be given. This may be done in two ways

• Ablative (myeloablative) treatment  – High-dose chemotherapy, radiation, or both are given to kill any cancer cells. This also kills all healthy bone marrow that remains and allows new stem cells to grow in the bone marrow.
• Reduced-intensity treatment also called a mini transplant – Lower doses of chemotherapy and radiation are given before a transplant. This allows older people, and those with other health problems to have a transplant.

Pre Procedure of Bone Marrow Transplant

• Major Histocompatibility Complex (MHC) – The group of genes on the short arm of chromosome 6 (p6) that encodes human leukocyte antigens (HLA) which are considered being highly polymorphic leading to a large difference in the resultant expressed proteins on human cells. They are divided into MHC I and MHC II
• Human Leukocyte Antigens (HLA) – These are the proteins expressed on the cellular surface and play an important role in alloimmunity. HLA can be divided into (HLA-A, B, and C) which are encoded by class I MHC and are expressed on all cell types and present peptides derived from the cytoplasm and are recognized by CD8+ T cells. The other HLA type is classified as (HLA- DP, DQ, and DR) which are encoded by MHC II and can be found on antigen-presenting cells (APCs) and this class is recognized by CD4+ T cells.
• Syngeneic Bone Marrow Transplantation – The donor and the recipient are identical twins. The advantages include no graft versus host disease (GVHD) and no graft failure. However, only a tiny number of transplant patients will have the ability to have an identical twin for transplantation.
• Autologous Bone Marrow Transplantation – The bone marrow products are collected from the patient and are reinfused after purification methods. The advantages include no GVHD. The disadvantage is that the bone marrow products may contain abnormal cells that can cause relapse in the case of malignancy hence; theoretically, this method cannot be used in all cases of abnormal bone marrow diseases.
• Allogenic Transplantation – The donor is an HLA matched family member, unrelated matched donor or mismatched family donors (haploidentical).
• Engraftment – The process of which infused transplanted hematopoietic stem cells produce mature progeny in the peripheral circulation
• Preparative Regimen – This is a regimen that comprises high-dose chemotherapy and/or total body irradiation (TBI) which are administered to the recipient prior to stem cell infusion to eliminate the largest number of malignant cells and to allow for immunosuppression in the recipient so that engraftment can occur.

Indications of Bone Marrow Transplant

Indications for stem cell transplantation are as follows:

Malignant (cancerous)

• Acute myeloid leukemia (AML)
• Chronic myeloid leukemia (CML)
• Acute lymphoblastic leukemia (ALL)
• Hodgkin lymphoma (HL) (relapsed, refractory)
• Non-Hodgkin lymphoma (NHL) (relapsed, refractory)
• Neuroblastoma
• Ewing sarcoma
• Multiple myeloma
• Myelodysplastic syndromes
• Gliomas, other solid tumors

Non-malignant (non-cancerous)

• Thalassemia
• Sickle cell anemia
• Aplastic anemia
• Fanconi anemia
• Malignant infantile osteopetrosis
• Mucopolysaccharidosis
• Pyruvate kinase deficiency
• Immune deficiency syndromes
• Autoimmune diseases^[rx]

Malignant Disease

• Multiple Myeloma – Autologous stem cell transplant accounts for most hematopoietic stem cell transplants according to CIBMTR in 2016 in the United States. Studies have shown increased overall survival and progression-free survival in patients younger than 65 years old when consolidation therapy with melphalan is initiated followed by autologous stem cell transplantation and lenalidomide maintenance therapy.[rx] The study showed a favorable outcome of high-dose melphalan plus stem-cell transplantation when compared with consolidation therapy with melphalan, prednisone, lenalidomide (MPR). It also showed a better outcome in patients who received maintenance therapy with lenalidomide.
• Hodgkin and Non-Hodgkin Lymphoma  – Studies have shown that chemotherapy followed by autologous stem cell transplantation in cases of recurrent lymphomas (HL and NHL) that do not respond to initial conventional chemotherapy have better outcomes. A randomized controlled trial by Schmitz N et al. showed a better 3-year outcome of high-dose chemotherapy with autologous stem cell transplant compared to aggressive conventional chemotherapy in relapsed chemosensitive Hodgkin lymphoma. However, the overall survival was not significantly different between the two groups.[rx] The number of hematopoietic stem cell transplant recipients comes second after multiple myeloma according to CIBMTR.
• Acute Myeloid Leukemia – Allogenic stem cell transplant has shown to improve outcomes in patients with AML who fail primary induction therapy and do not achieve a complete response and may prolong overall survival.[rx] The study recommended that early HLA typing for patients with AML can help if they fail induction therapy and are considered for bone marrow transplant.
• Acute Lymphocytic Leukemia – Allogenic stem cell transplant is indicated in refractory and resistant cases when induction therapy fails for the second time in inducing remission. Some studies suggest an increased benefit of allogeneic hematopoietic stem cell transplant in patients with high risk ALL including patients with Philadelphia chromosome and those with t(4, 11).[rx]
• Myelodysplastic Syndrome – Allogenic stem cell transplant is considered being curative in cases of disease progression and is only indicated in intermediate- or high-risk patients with MDS.
• Chronic Myeloid Leukemia/Chronic Lymphocytic Leukemia – Recipients with these two diseases come at the bottom of the list of patients who received allogeneic stem cell transplant in 2016. Hematopoietic stem cell transplantation has shown high cure rates but with available treatments like tyrosine kinase inhibitors and high success rates with the low adverse risk profile, HSCT is reserved for patients with the refractory disease to first-line agents in CML.
• Myelofibrosis, Essential Thrombocytosis, and Polycythemia Vera – Allogenic stem cell transplant has shown to improve outcomes in patients with myelofibrosis and those who had a diagnosis of myelofibrosis that was preceded by essential thrombocytosis and polycythemia vera.[rx]
• Solid Tumors – Autologous stem cell transplant is considered the standard of care in patients with germ cell tumors (testicular tumors) that are refractory to chemotherapy (after the third recurrence with chemotherapy).[rx] HSCT has also been studied in medulloblastoma, metastatic breast cancer, and other solid tumors.

Non-Malignant Diseases

• Aplastic Anemia – Systematic and retrospective studies have suggested an improved outcome with hematopoietic stem cell transplant in acquired aplastic anemia when compared with conventional immunosuppressive therapy.[rx] Allogenic stem cell transplant has shown better outcomes when it was collected from bone marrow compared to peripheral blood in a study that involved 1886 patients with acquired aplastic anemia.[rx] Patients with aplastic anemia need a preparative regimen given they still can develop immune rejection to the graft.
• Severe Combined Immune Deficiency Syndrome (SCID) – Large retrospective studies have shown increased overall survival in infants with SCID when they received the transplant early at birth before the onset of infections.[rx]
• Thalassemia – Allogenic stems transplant from a matched sibling donor is considered an option to treat Thalassemia and has shown 15-year survival reaching 80%. However, recent retrospective data showed similar overall survival compared with conventional treatment that consists of multiple transfusions in the case of thalassemia.[rx]
• Sickle Cell Anemia – Allogenic stem cell transplant is recommended for the treatment of sickle cell disease.[rx]
• Other Nonmalignant Diseases  – Stem cell transplant has been used in the treatment of chronic granulomatous disease, leukocyte adhesion deficiency, Chediak-Higashi syndrome, Kostman syndrome, Fanconi anemia, Blackfan-Diamond anemia, and enzymatic disorders. Moreover, the role of stem cell transplant is being explored in autoimmune diseases including systemic sclerosis, systemic lupus erythematosus, and has already shown promising results in cases like relapsing-remitting multiple sclerosis.[rx]

Contraindications of Bone Marrow Transplant

There are no absolute contraindications for hematopoietic stem cell transplant.

Rules for bone marrow transplant

These rules have been prepared as a guide for patients and their relatives.

• Stick to the physician’s prescription in using all medications.
• Make sure to come for regular check-ups. Please, arrive on an empty stomach and without having used any medication.
• Chemotherapy will inhibit the optimum functioning of the immune system for about a year. This is why it is very important to give extra care and attention to personal hygiene, nutrition, use of protective masks, accepting visitors, handshakes, and sexual relations throughout the entire year.
• Instructions for daily life after bone marrow transplant
• Your home should be especially clean following the transplant. Allocate a separate room for the patient. Remove dust magnet such as thick carpets and curtains from this room. Do not clean and air the patient’s room which he/she is still inside. If the room/home lacks central heating, make sure to light and clean the fire stove when the patient is outside the room. Adjust the room temperature carefully.
• The patient’s room must be away from any type of construction activity.
• All house plants and any kind of pet including cats, dogs, fish, and birds must be removed from the house for a year due to the risk of infection.
• Make sure to keep the rest of the house equally clean and tidy.
• Pay attention to land hygiene, take a wash at least two times a day, allocate a separate towel for the patient, and prevent its use by anyone else. Wash and iron the towel after each use. Take showers instead of baths, and use only moisturizing soaps.
• Use a paper towel for hand and face hygiene.
• Do not have guests for the first 100 days. Reduce the number of guests as much as possible in the subsequent period. Refrain from close contact including kissing, handshaking, and cuddling.
• Change the patient’s bed linen at least twice a week, frequently air the mattress.
• Do not use feather and wool-stuffed pillows.
• Make sure to wash all new clothes before use. Do not use corduroy or plush textiles.
• Make sure that the patient uses two masks whilst traveling or outdoors.
• Patients should not swim for a year (sea or pool) and should not use saunas.
• Prevent direct contact with sunlight for one year. Walks should be taken in the afternoon.
• Women should not get epilation for one year. Depilatory creams may be used if the physician approves.
• Give extra care to hygiene when getting the patient’s haircut.
• Brush teeth with a soft brush 3 times a day, try not to get gums bleeding.
• Do not use deodorants, perfumes, makeup, or hair dye for a year.
• Do not smoke or consume alcohol, steer clear of smoky, dusty, and dirty environments.
• Do not come in contact with people who have cold, flu, or infection.
• Immediately seek medical attention in case of bleeding, bruising, and swelling.
• Dress according to climate, avoid getting ill.
• Menstruation irregularities may develop in women following the transplant. Seek medical attention from the gynecology department in accordance with the physicians’ recommendations.
• Treatment will cause a loss in a sense of thirst, hunger, and taste for the first three months after the transplant. This is why patients have to drink three liters of water per day for a year. Drinking less can result in serious electrolyte disorder thus increasing the risk of getting sick. Liquid intake may also be supported by drinking milk, diluted yogurt, tea, fruit juice, or soup. Chew sugar-free chewing gum for building an appetite or suck on sweets for a sense of taste. Drink homemade lemonade 30 minutes before meals, if feeling nauseous.
• Do not drink spring water from unknown sources. Only drink bottled water.
• Use only pasteurized milk and cheese.
• Milk taken outside should be boiled for 15 minutes.
• Take single-use pasteurized and homemade yogurt.
• Thoroughly rinse all fruit and vegetables, leave them in water with vinegar for 30 minutes, and peel all skin before consuming.
• Eat seasonal fruit and vegetables. Avoid consuming processed foods and drinks with additives.
• Thoroughly cook all food. Strictly avoid eating salami, sausage, bacon, cured meat, spices, raw onions and garlic, tomato paste, animal fat, innards, legumes, pickles, creams, kebabs, pizzas, burgers and any sort of fast foods.
• Thoroughly cook all meats and eggs, make sure eggs are not cracked.
• Do not crack nuts with your teeth, use nutcrackers.
• Refrain from eating strawberries as they grow too close to the soil.
• Do not eat frozen, stale, or canned food. Food should be consumed in 24 hours.
• Store food in airtight containers.
• Use latex gloves to prepare food.
• Use mask whilst preparing food for the patient.
• Pay attention to expiration dates for all products and foods.
• Do not discuss distressing issues with the patient. Keep patient’s spirit high

Equipment

Special equipment exists for the collection, preservation, and administration of stem cell products. An interprofessional team approach is a mainstay of ensuring the high-quality collection and infusion of stem cell products.

Preparation

Preparation includes:

• Preparative regimen
• Collection of hematopoietic stem cells
• Instant infusion or cryopreservation followed by infusion

Technique

Mechanism of Action

The mechanism of action of stem cell transplant against malignancy in leukemia is based on the effect of the graft and donor immunity against malignant cells in recipients. These findings were demonstrated in a study that involved over 2000 patients with different leukemia. These patients received stem cell transplantation and showed that the lowest rate of relapses was in patients who received non-T-cell-depleted bone marrow cells and in those who developed GVHD compared to patients who received T-cell-depleted stem cells, those who did not develop GVHD, and patients who received syngeneic grafts. These findings support the notion that donor cellular immunity plays a central role in the engraftment’s efficacy against tumor cells.[rx]

The mechanism of action in autoimmune diseases is believed to be secondary to the increase in T-cell regulatory function which promotes immune tolerance. However, more studies are still needed to determine the exact pathophysiology.

In hemoglobinopathies, the transplanted stem cells produce functional cells after engraftment that replaces the diseased cells.

HLA Typing and Administration

HLA typing is an important step to determine the best donor suitable for stem cell collection. In theory, matched, related donors are the best candidates, followed by matched unrelated donors, cord blood, and then haploidentical donors. HLA typing is analyzed at either an intermediate-resolution level, which entails the detection of a small number of matched alleles between the donor serum and the recipient, or at a high-resolution level to determine the specific number of polymorphic alleles at a higher level. PCR and next-generation sequencing are used for HLA typing, and the results are reported as a score correlating with a match of two alleles for a specific HLA type. Different institutions use a different number of HLA subtypes for eligibility of donors but according to studies that showed matching for HLA-A, B, C, and DRB1 at a high-resolution level were associated with improved survival and outcomes.[rx] Recommendations about donor HLA assessment and matching have been proposed by the Blood and Marrow Transplant Clinical Trials Network (BM CTN).[rx]

The process may vary depending on the source of the stem cell site collection, whether it is bone marrow, peripheral blood, or cord blood. Moreover, there is a slight difference based on whether it is autologous, allogeneic, or syngeneic. For example, the procedure consists of initial mobilization of stem cells, in which peripheral blood stem cells are collected given the low number and the need for high levels of progeny cells, and then this is followed by a preparative regimen and finally, infusion.

Mobilization and collection involved the use of medication to increase the number of stem cells in the peripheral blood given that there are not enough stem cells in the peripheral blood. The agents used include granulocyte colony-stimulating factors (G-CSF) or chemokine receptor 4 (CXCR4) blockers like plerixafor. G-CSF is believed to enhance neutrophils to release serine proteases which lead to a break of vascular adhesion molecules and the release of hematopoietic stem cells from the bone marrow. Plerixafor blocks the binding of stromal cell-derived factor-1-alpha (SDF-1) to (CXCR4) which leads to the mobilization of stem cells to the peripheral blood.[rx] CD34+ is considered the marker for progenitor hematopoietic stem cells in the peripheral blood, and usually, a dose of 2 to 10 x 10/kg CD34+ cells/kg is needed for proper engraftment. Chemotherapy can be used in some instances for mobilization of hematopoietic stem cells; this process is termed chemoembolization.

The usual site of bone marrow collection is the anterior or posterior iliac crest. The procedure can be performed under local or general anesthesia. Complications include pain, fever, and serious iatrogenic complications can occur in less than 1% of cases. Multiple aspirations are done with each aspirate containing 15 mL. The goal is to collect up to 1 to 1.5 L of bone marrow product from the aspirations. The dose of nucleated cells from bone marrow should range between 2 to 4 x 10 cells/kg as studies showed that overall survival and long-term engraftment is strongly influenced by cell dose in allogeneic hematopoietic stem cell transplantation.[rx]

The preparative regimen consists of administration of chemotherapy with or without total body irradiation for the eradication of malignant cells and induction of immune tolerance for the transfused cells to engraft properly. This process is not only limited to patients with malignancies but also extends to cases like aplastic anemia and hemoglobinopathies given that these patients have an intact immune system that could cause graft failure if there is no conditioning.

The preparative regimen is divided into myeloablative conditioning and reduced-intensity conditioning. The preparative regimen depends on the disease being treated, existing comorbidities, and the source of the harvested hematopoietic stem cells. The preparative regimen consists of chemotherapy, total body irradiation, or both. There are different combination regimens used in the preparative period, and the choice of the regimen depends on the disease being treated, existing comorbidities, and previous exposure to radiation.

In the special case of SCID, there is no need for a preparative regimen in patients receiving from HLA-matched siblings given that there are no abnormal cells that are needed to be eliminated and because immunosuppression caused by SCID can prevent graft rejection. Reduced-intensity conditioning is preferred in patients with prior radiotherapy, older age, the presence of comorbidities, and history of extensive chemotherapy before BMT.[rx] The advantages of using reduced-intensity conditioning include less need for transfusion due to the transient post-transplant pancytopenia and less damage to the liver in cases of chemotherapy and lung due to radiation.[rx] However, the relapse rates are higher, but these regimens are more tolerated with a better safety profile in a specific patient population. Most of the chemotherapies used in preparative regimens consist of either potent immunosuppressive agents (high doses of cyclophosphamide 60 mg/kg IV), alkylating agents especially busulfan 130 mg/m2 IV, nucleoside analogs (fludarabine 40 mg/m2) and other agents like melphalan, antithymocyte globulin, rituximab, gemcitabine, and many others. Total body irradiation (TBI) is performed using fractionated doses because it has shown less pulmonary toxicity when compared with one dose regimen.[rx] The administration of the preparative regimen should immediately precede the bone marrow transplantation, and as a general rule, the effect of the regimen should produce bone marrow suppression within 1 to 3 weeks of administration.

Reinfusion of either fresh or cryopreserved stem cells can occur in an ambulatory setting and takes up to 2 hours. Before the infusion begins, quality measures are performed to ensure the number of CD34+ cells is sufficient.

Rehabilitation after stem cell transplant

The process of stem cell transplant doesn’t end when you go home. You’ll feel tired, and some people have physical or mental health problems in the rehabilitation period. You might still be taking a lot of medicines. These ongoing needs must now be managed at home, so caregiver and friend/family support is very important.

Transplant patients are followed closely during rehab. You might need daily or weekly exams along with things like blood tests, and maybe other tests, too. During early rehab, you also might need blood and platelet transfusions, antibiotics, or other treatments. At first you’ll need to see your transplant team often, maybe even every day, but you’ll progress to less frequent visits if things are going well. It can take 6 to 12 months, or even longer, for blood counts to get close to normal and your immune system to work well. During this time, your team will still be closely watching you.

Some problems might show up as much as a year or more after the stem cells were infused. They can include:

• Graft-versus-host disease (in allogeneic transplants)
• Infections
• Lung problems, such as pneumonia or inflammation that makes it hard to breathe
• Kidney, liver, or heart problems
• Low thyroid function
• Overwhelming tiredness (fatigue)
• Limited ability to exercise
• Slowed growth and development (in children)
• Cataracts
• Reproductive or sexual problems, like infertility, early menopause, pain or discomfort during sex, or loss of interest in sex
• New cancers caused by the transplant

Other problems can also come up, such as:

• Memory loss, trouble concentrating
• Emotional distress, depression, body image changes, anxiety
• Social isolation
• Changes in relationships
• Changes in how you view the meaning of life
• Feeling indebted to others
• Job and insurance concerns

What complications and side effects may happen following BMT?

Complications may vary, depending on the following:

• Type of marrow transplant
• Type of disease requiring a transplant
• Preparative regimen
• Age and overall health of the recipient
• The variance of tissue matching between donor and recipient
• Presence of severe complications

The following are complications that may happen with a bone marrow transplant. However, each individual may experience symptoms differently. These complications may also happen alone, or in combination:

• Infections – Infections are likely in the patient with severe bone marrow suppression. Bacterial infections are the most common. Viral and fungal infections can be life-threatening. Any infection can cause an extended hospital stay, prevent or delay engraftment, and/or cause permanent organ damage. Antibiotics, antifungal medicines, and antiviral medicines are often given to try to prevent serious infection in the immunosuppressed patient
• Low platelets and low red blood cells – Thrombocytopenia (low platelets) and anemia (low red blood cells), as a result of nonfunctioning bone marrow, can be dangerous and even life-threatening. Low platelets can cause dangerous bleeding in the lungs, gastrointestinal (GI) tract, and brain.
• Pain – Pain-related to mouth sores and gastrointestinal (GI) irritation is common. High doses of chemotherapy and radiation can cause severe mucositis (inflammation of the mouth and GI tract).
• Fluid overload – Fluid overload is a complication that can lead to pneumonia, liver damage, and high blood pressure. The main reason for fluid overload is because the kidneys cannot keep up with a large amount of fluid being given in the form of intravenous (IV) medicines, nutrition, and blood products. The kidneys may also be damaged from disease, infection, chemotherapy, radiation, or antibiotics.
• Respiratory distress – Respiratory status is an important function that may be compromised during transplant. Infection, inflammation of the airway, fluid overload, graft-versus-host disease, and bleeding are all potentially life-threatening complications that may happen in the lungs and pulmonary system.
• Organ damage – The liver and heart are important organs that may be damaged during the transplantation process. Temporary or permanent damage to the liver and heart may be caused by infection, graft-versus-host disease, high doses of chemotherapy and radiation, or fluid overload.
• Graft failure – Failure of the graft (transplant) taking hold in the marrow is a potential complication. Graft failure may happen as a result of infection, recurrent disease, or if the stem cell count of the donated marrow was insufficient to cause engraftment.
• Graft-versus-host disease – Graft-versus-host disease (GVHD) can be a serious and life-threatening complication of a bone marrow transplant. GVHD occurs when the donor’s immune system reacts against the recipient’s tissue. As opposed to an organ transplant where the patient’s immune system will attempt to reject only the transplanted organ, in GVHD the new or transplanted immune system can attack the entire patient and all of his or her organs. This is because the new cells do not recognize the tissues and organs of the recipient’s body as the self. Over time and with the help of medicines to suppress the new immune system, it will begin to accept its new body and stop attacking it. The most common sites for GVHD are the GI tract, liver, skin, and lungs.

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