<unk>  is associated with a high treatment-related mortality in the recipient, which limits its use to conditions that are themselves life-threatening. (The one-year survival rate has been estimated to be roughly 60%, although this figure includes deaths from the underlying disease, as well as from the transplant procedure.) Major complications include veno-occlusive disease, mucositis, infections (sepsis), graft-versus-host disease, and the development of new malignancies. Infection Bone-marrow transplantation usually requires that the recipient's own bone marrow be destroyed (myeloablation). Prior to the administration of new<unk> s (engraftment), patients may go for several weeks without appreciable numbers of white blood<unk> s to help fight infection. This puts a patient at high risk of infections, sepsis, and septic shock, despite prophylactic antibiotics. However, antiviral medications, such as acyclovir and valacyclovir, are quite effective in prevention of<unk> -related outbreak of herpetic infection in seropositive patients. The immunosuppressive agents employed in allogeneic transplants for the prevention or treatment of graft-versus-host disease further increase the risk of opportunistic infection. Immunosuppressive drugs are given for a minimum of six months after a transplantation, or much longer if required for the treatment of graft-versus-host disease. Transplant patients lose their acquired immunity, for example immunity to childhood diseases such as measles or polio. So, transplant patients must be retreated with childhood vaccines once they are off immunosuppressive medications. Veno-occlusive disease Severe liver injury can result from hepatic veno-occlusive disease (VOD), newly termed sinusoidal obstruction syndrome (SOS). Elevated levels of bilirubin, hepatomegaly, and fluid retention are clinical hallmarks of this condition. The appreciation of the generalized<unk> ular injury and obstruction in hepatic vein sinuses is now greater. Severe cases of SOS are associated with a high mortality rate. Anticoagulants or defibrotide may be effective in reducing the severity of VOD but may also increase bleeding complications. Ursodiol has been shown to help prevent VOD, presumably by facilitating the flow of bile. Mucositis The injury of the mucosal lining of the mouth and throat is a common regimen-related toxicity following ablative<unk>  regimens. It is usually not life-threatening, but is very painful, and prevents eating and drinking. Mucositis is treated with pain medications plus intravenous infusions to prevent dehydration and malnutrition. Hemorrhagic cystitis The mucosal lining of the bladder is affected in about 5% of children undergoing<unk> . This causes hematuria (blood in urine), frequent urination, abdominal pain and thrombocytopenia. Graft-versus-host disease Graft-versus-host disease (GvHD) is an inflammatory disease that is unique to allogeneic transplantation. It is an attack by the "new" bone marrow's immune<unk> s against the recipient's tissues. This can occur even if the donor and recipient are HLA-identical because the immune system can still recognize other differences between their tissues. It is aptly named graft-versus-host disease because bone-marrow transplantation is the only transplant procedure in which the transplanted<unk> s must accept the body rather than the body accepting the new<unk> s. Acute GvHD typically occurs in the first three months after transplantation and may involve the skin, intestine, or liver. High-dose corticosteroids, such as prednisone, are a standard treatment, but this immunosuppressive treatment often leads to deadly infections. Chronic GvHD may also develop after allogeneic transplant. It is the major source of late treatment-related complications, although it less often results in death. In addition to inflammation, chronic GvHD may lead to the development of fibrosis, or scar tissue, similar to scleroderma; it may cause functional disability and require prolonged immunosuppressive therapy. GvHD is usually mediated by T<unk> s, which react to foreign peptides presented on the major histocompatibility complex of the host. Further research is needed to determine whether mesenchymal stromal<unk> s can be use for prophylaxis and treatment of GvHD. Graft-versus-tumor effect Graft-versus-tumor effect (GVT), or "graft versus leukemia" effect, is the beneficial aspect of the GvHD phenomenon. For example,<unk>  patients with either acute, or in particular chronic, GvHD after an allogeneic transplant tend to have a lower risk of cancer relapse. This is due to a therapeutic immune reaction of the grafted donor T lymphocytes against the diseased bone marrow of the recipient. This lower rate of relapse accounts for the increased success rate of allogeneic transplants, compared to transplants from identical twins, and indicates that allogeneic<unk>  is a form of immunotherapy. GVT is the major benefit of transplants that do not employ the highest immunosuppressive regimens. Graft versus tumor is mainly beneficial in diseases with slow progress, e.g. chronic leukemia, low-grade lymphoma, and in some cases multiple myeloma, but is less effective in rapidly growing acute leukemias. If cancer relapses after<unk> , another transplant can be performed, infusing the patient with a greater quantity of donor white blood<unk> s (donor lymphocyte infusion). Malignancies Patients after<unk>  are at a higher risk for oral carcinoma. Post-HSCT oral cancer may have more aggressive behavior with poorer prognosis, when compared to oral cancer in non-HSCT patients. A meta-analysis showed that the risk of secondary cancers such as bone cancer, head and neck cancers, and melanoma, with standardized incidence ratios of 10.04 (3.48–16.61), 6.35 (4.76–7.93), and 3.52 (2.65–4.39), respectively, was significantly increased after<unk> . So, diagnostic tests for these cancers should be included in the screening program of these patients for the prevention and early detection of these cancers.
Hematopoietic stem cell transplantation
Syngeneic stem cell transplantation
Stem-cell therapy
Peripheral stem cell transplantation
Autologous stem-cell transplantation
Thymus transplantation
Autologous immune enhancement therapy
Spleen transplantation