Stem cell or bone marrow transplants are complex treatments that carry a significant risk of serious complications. One of the most concerning complications is graft failure, which occurs when the body rejects the new stem cells that were administered. This can happen if the stem cells do not reach the bone marrow or multiply as they should. Graft failure is more common when there is a poor match between the patient and donor, or when stem cells are obtained from a donor with removed T cells.
It can also occur in patients who receive a low amount of stem cells, such as a single umbilical cord unit. The disparity between the recipient and the donor within the major histocompatibility complex (MHC) is of paramount importance for allograft rejection. In fact, studies have shown that patients who receive transplants from siblings identical to HLA have a much lower rejection rate compared to those who receive grafts that are not compatible with HLA. Similarly, stem cell recipients from unrelated donors also have a higher risk of graft failure compared to patients who receive grafts from siblings identical to HLA. In cases where unrelated donors are used, a disparity in HLA class I between donor and recipient has been associated with a higher risk of rejection. The risk of graft failure usually lasts for two to four weeks after the transplant, but it can also occur later on.
If the graft fails, doctors may recommend transplanting more donor stem cells if they are available. This is because graft failure occurs when the transplanted stem cells do not settle in the bone marrow or produce new blood cells, resulting in low blood counts. While graft failure is serious, it is very rare after an autologous stem cell transplant. However, it is important for the medical team to closely monitor blood counts to catch any signs of graft failure early on. If the graft does not work, initial treatment may involve the use of growth factors or hormones to stimulate bone marrow stem cells to produce more cells.
In some cases, a second stem cell transplant may be necessary. It is worth noting that people who receive their own stem cell transplants (autologous transplants) are less likely to suffer serious side effects compared to those who receive transplants from a donor. At four weeks post-transplant, a bone marrow aspirate showed 95% of recipient cells among the CD34+ cells and 80% of recipient T cells. This means that the majority of the cells in the bone marrow were from the recipient rather than the donor. This is an important factor in preventing graft failure and ensuring a successful transplant. If you are going to have a donor stem cell transplant (allogeneic transplant), you will need a suitable donor.
It is also important to take precautions against infections during this time, as patients undergoing high-dose chemotherapy and autologous hematopoietic stem cell transplantation are at a higher risk of developing infections. Patients with lymphoma may require a stem cell transplant if they need cancer treatment in high doses. One of the most concerning complications of an allogeneic transplant is graft-versus-host disease (GVHD). This occurs when the transplanted stem cells from a donor produce immune system cells that attack the recipient's tissues and organs. Some side effects of a bone marrow or stem cell transplant may not show up until several months or even years after treatment.
However, GVHD can be treated with medications that suppress the immune system and prevent transplanted stem cells from attacking the rest of the body. In all types of transplants, patients are treated with chemotherapy followed by an infusion of a blood-forming stem cell graft from a suitable donor. For at least the first six weeks after the transplant, until the new stem cells start producing white blood cells, patients are at a higher risk of developing serious infections. It may take three to six months for patients to fully recover from an autologous stem cell transplant, while those who receive a transplant using donor stem cells may take longer. If you or a loved one is considering a stem cell transplant, it is important to understand the risks and potential complications involved. However, with proper monitoring and precautions, the chances of a successful transplant are high.
Organizations like Macmillan Cancer Support and Anthony Nolan provide valuable information and resources for those undergoing stem cell transplants for blood cancers like lymphoma.
