Challenges in a half-matched BMT:

Challenges in a half-matched BMT are doubled compared to a full-matched bone marrow transplant. However, the results are the same to that of a full matched transplant once fully engrafted, and if the complications are less severe.

For example, the results and the number of survival years are the same for a patient with thalassemia major, whether the transplant is a half-matched or fully matched.

What are the factors for a successful half-matched transplant?

Furthermore, the success of the half-matched transplant depends upon several factors as follows:

Type of the disease: (Challenges in a half-matched BMT)

A half-matched transplant is indicated for both a benign disease, such as APLASTIC ANEMIA or thalassemia major OR a malignant disease such as leukemia (blood cancer).

Nature of the disease: Challenges in a half-matched BMT

The success of a half-matched transplant also depends upon the nature of the disease; the more aggressive the disease the results will be.

For example, half matched transplant for a patient with thalassemia with multiple blood transfusions could lead to rejection of the transplanted stem cells due to the presence of antibodies against the donor cells from multiple transfusions.

 Moreover, a half-matched transplant for a patient with leukemia undergone remission after so many chemotherapy treatment lines could also lead to rejection due to poor disease control and the aggressive nature of the disease.

Age of the recipient and donor: Challenges in a half-matched BMT

In a stem cell or a bone marrow transplant age of both the recipients and the donor matters. It is usually recommended that the donor and the recipients should be less than 60 years of age for leukemia and other blood-related diseases.

However, for thalassemia, the recommended age should be less than 3 years or not more than 5 years forfewers complications and good transplant results. So, younger age results in e more success, and old age results in less success.

Why is old age or being above 60 years discouraged?

Old age patients for transplant are not good candidates for a bone marrow or a stem cell transplant due to the following reasons:

• Multiple  comorbidities such as poor heart health, poor gut health, weak immunity, and compromised lung health due toprolongedg exposure to toxins inthe environment
• Less stamina to tolerate high-dose chemotherapy or radiation therapy, as the side effects of high-dose chemotherapy and radiation therapy are very aggressive during transplant.
• More antibodies against donor cells due to prolonged exposure to different antigens. This could lead to transplant rejection.

Amount of the collected and infused stem cells: Challenges in a half-matched BMT

The success of a half-matched transplant also depends upon the dose of collected stem cells. As the stem cell dose is standardized internationally.

The minimum requirement for an autologous bone marrow transplant is a minimum 3million /kg body weight. Whereas the maximum stem cell dose is 5 million /kg body weight.

However, for a full matched or a half matched bone marrow transplant, the stem cell dose is a minimum of 5 million /kg body weight and a maximum of 8 million /kg body weight.

In some centers, the requirement for a half-matched transplant is at least 10 million /kg body weight.

What will be the risk if the stem cells are less than the required dose?

If the cells are less than the required dose, there could be a chance of poor engraftment or engraftment failure. In this stage, especially in an autologous transplant.

If the graft failure occurs, there is very little chance to save the patient. If the source for the second stem cells is not on hand, because the bone marrow of the patient has been destroyed with a high dose of chemotherapy or radiation therapy.

What will happen if the stem cell dose is more than the required dose?

In case of administering more stem cells to the recipient, there are chances of graft versus disease. This could be skin, the gut of the liver.

Sometimes the GvHD becomes so severe that it is difficult to control with medication. Therefore, it is recommended to infuse the cells in a normal amount.

What are the risks in a half-matched transplant?

As discussed, a half-matched transplant is more challenging than a full-matched transplant.

The following side effects are noted in a half-matched transplant.

• Higher risk of Graft versus Host disease
• More chances of graft rejection
• More side effects of chemotherapeutic drugs or radiation therapy
• Patient becomes high risk for infections due to double myelosuppressive medications.
•  Risk of delayed engraftment due to a partially matched HLA type.
• More hospital stays
• High costs due to prolonged hospital stays, especially in developing countries, where facilities are limited.
• Frequent hospital admissions due to infections and graft versus host diseases
• Less chances of survival if the engraftment is poor.
• Reactivation of cytomegalovirus (CMV).
• The CMV virus is usually present in all healthy individuals, but it becomes active in patients with compromised immunity. If it becomes active after transplant, the medication used to treat this infection further weakens the patient’s immune system of the patient;
• This further increases the risk of infections and increases the requirement for blood and blood product administration.
• The side effects of anti-CMV treatment include a decrease in white blood cell count.
• A decrease in the number of platelets and a decrease in hemoglobin.
• Due to which patient needs transfusions and sometimes needs to stay in the hospital for a long time.
• Change in skin and nutrition due to graft versus host disease

What precautionary measures should be taken to lessen the complications in a half-matched transplant?

A healthcare provider should keep in mind to minimize complications in a half-matched transplant.

• HLA antibodies against the donor must be checked before transplant.
• If the antibodies are reactive, they should be desensitized before proceeding to transplant.
• The chemotherapy regimen must be selected according to the physical fitness of the patient.s
• Patients and families should be taught and informed about the expected outcome of a half-matched transplant.
• A healthcare provider should explain the importance of myelosuppressive medicine, for example, in case of a missed dose, the higher chances of graft versus host disease.
• Proper teaching should be given to the patient regarding symptoms of Graft versus host disease (liver, gut, or skin) so that the patient can report earlier to the healthcare facility.
• Secondly, drug-to-drug interaction, drug-to-food interaction, and diet and exercise should be given as a compulsory part of the transplant.

Hence, transplant-associated side effects could be minimized by effective teaching after transplant, regarding diet, exercise, drug-to-drug interaction, and drug-to-food interaction.

Moreover, an expert transplant team consists of transplant-specialized doctors, nurses, and paramedics who are required to handle complications of a half-matched transplant.