Introduction
Blood group matching is vital for lung transplantation. Unfortunately, this restricts the opportunity of receiving transplants in many patients. Enzymatic treatment of the lungs removes this hindrance and makes it a universally available lung for transplant. Enzymatically treated lungs are blood-group-independent lungs. This reduces the wait time for patients with progressively failing lungs to receive lung transplants.
What Is a Lung Transplant?
Lung transplantation is a surgical procedure in which a failing or diseased lung is replaced with a healthy lung from a dead donor. A transplant is done if the condition of the lungs has not improved with treatments and medications. A lung transplant involves replacing one or both lungs with the donor.
Why Is Lung Transplant Done?
A lung transplant is done when the lungs are damaged and the body does not receive enough oxygen to survive. Chronic obstructive pulmonary disease (COPD), pulmonary emphysema, cystic fibrosis, pulmonary hypertension, and other conditions like sarcoidosis, histiocytosis, and lymphangioleiomyomatosis damage lung function. This can be treated with medications or breathing devices. But when these treatments do not help or the physician suggests a lung transplant if the lung function is deteriorating.
Who Is Eligible for Lung Transplant?
A lung transplant cannot be done for all patients. A patient is not a candidate for transplant if one of the following conditions is present.
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Active infection.
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Recent history of cancer.
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Kidney, liver, or heart diseases.
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Chronic alcoholism.
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Chronic smoking.
What Are the Tests Done Before Lung Transplant?
Blood and tissue typing and human leukocyte antigen (HLA) sensitivity analysis are done before transplantation. The donor's and recipient's blood and tissue type should match to prevent transplant rejection.
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Blood Typing and Compatibility involves testing the ABO compatibility of the donor and the recipient.
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Recipients with blood group A are compatible with blood group A or O donors.
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Recipients with blood group B are compatible with blood group B or O donors.
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Recipients with blood group AB are universally compatible with blood group A, B, AB, or O donors.
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Recipients with blood group O are compatible with blood group O donors. People with blood group O are universal donors because the O group is compatible with all blood groups.
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Tissue Typing and Compatibility - Human leukocyte antigen consists of proteins that recognize and destroy foreign substances. In HLA-sensitized recipients, the recipients develop antibodies to the donor's HLA. If the transplant is not HLA compatible, the recipient's immune system attacks the HLA cells in the transplant and destroys them. This results in transplant rejection and failure.
What Are the Risks Involved in Lung Transplantation?
The risks involved in lung transplantation can be severe and fatal. Rejection and infection are the common risks involved. Even after proper blood and tissue typing and human leukocyte antigen compatibility testing, the immune system attacks the donor's lung and rejects it. Immunosuppressant drugs after surgery suppress the immune system and increase susceptibility to infections.
What Is the Major Drawback?
A lung transplant takes place after the patient registers in a transplant center. The name of the patient is placed on a waiting list. The waiting period is more because the number of patients waiting for a transplant is higher than the number of available donors. When the donor is available, the donor-recipient compatibility is tested based on the blood group, size of the organ compared with the chest cavity, geographic distance between the donor and the recipient, the severity of the recipient's lung condition, and the recipient's health. ABO matching is a significant drawback because donor lung allocation depends on these criteria, limiting the opportunity of receiving a life-saving lung transplant. To overcome this challenge, scientists Wang et al. introduced the enzymatic treatment.
What Is Enzymatic Treatment?
Blood group A has A antigens on the red blood cells and anti-b antibodies in the plasma. The blood group O has no antigens. FpGaINAc deacetylase and FpGalactosaminidase combine to convert blood group A (ABO-A) into group O (ABO-O). These enzymes remove the A antigen from the donor's lungs using ex vivo lung perfusion (EVLP). Ex vivo refers to a procedure carried out outside the human body. FpGaINAc and FpGalactosaminidase are the enzymes present in the human gut. They digest the sugar antigens on the gut wall and release energy. These sugar antigens are similar to A antigens. Hence, these enzymes recognize the A antigens on the donor's lung and destroy them, leaving behind the O structure. This makes the donor lung universally compatible with recipients with any blood group.
What Are the Benefits of Enzymatic Treatment?
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Reduced antibody binding, complement deposition, and antibody-mediated injury.
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Reduces the waiting time for transplants.
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Reduces the shortage of O lungs and the waiting time because patients with O group are compatible only with donors of group O.
What to Expect After a Lung Transplant?
After a lung transplant, a mechanical ventilator assists with breathing for a few days. After discharge, three months of frequent monitoring is done to prevent, detect and treat complications and to assess the lung function. The patient is also monitored for signs and symptoms of rejection, like shortness of breath, fever, cough, and chest congestion. Medications like immunosuppressants are given for a lifetime to suppress the immune system to prevent transplant rejection. Antibiotics may be prescribed to avoid infections. Follow-up visits include:
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Blood tests.
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Pulmonary function tests.
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Chest X-rays.
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Examination of airways using bronchoscopy.
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Tissue from the lungs was removed for analysis.
It is essential to follow a healthy lifestyle and quit tobacco use to maintain the health of the transplanted lungs. Exercise is a vital part of rehabilitation after surgery. Emotional support is crucial in lung transplant patients.
Conclusion
A lung transplant is an effective treatment for people with failing lung function. It improves the quality of life. Inventions like enzymatic treatment constitute a significant advantage as they improve the chances of receiving a lung transplant and shorten the waiting period. However, the risks and complications of lung transplants are inevitable.
