Scientists in Toronto, Canada, have developed a technique that could make organs for transplantation suitable for any recipient, avoiding the need to find compatible organs, facilitating equity in the allocation of this valuable medical resource.
The research, published in Science Translational Medicine, has been carried out on donor lungs maintained ex vivo, that is, outside the body, but it involves a proof of concept that could presumably be extended to any organ for transplantation.
In addition to the shortage of organs, a problem for patients waiting to receive a transplant is the need for the available organ to be biologically compatible, otherwise their immune systems would reject it and this could endanger their lives.
This compatibility depends on three fundamental factors: the BLOOD GROUP, as in blood transfusions; the HLA SYSTEM, which comprises a set of proteins located on the surface of certain cells in our body that must be similar in the donor and the recipient to minimize the immune rejection response; and the absence of ANTIBODIES AGAINST THE GRAFT in the recipient of the organ, which are investigated by means of the so-called “cross-match”, to dissmiss that the recipient has antibodies directed against the donor’s cells.
The first of these factors, blood group, is the subject of the current study. The ABO blood group system establishes a classification of the different types of human blood, which are differentiated by the presence or absence of certain markers on the surface of the red blood cells.
The four main blood types are A, B, O, and AB. People with blood type O can donate blood or organs to anyone and are called universal donors. People with blood type AB, on the other hand, are universal recipients, they can receive any type. People with type A or B can receive blood or organs only of the same type as themselves or type O.
The need for ABO compatibility restricts the opportunity for some patients to receive a life-saving transplant. Faced with this problem, the authors of the work we are commenting on have studied the possibility of converting organs for transplantation to type O, to make them ‘universal’. Specifically, they have tested the strategy in eight ex vivo human lungs, successfully achieving transformation from group A to group O.
To do this, they have used a combination of the enzymes FpGalNAc deacetylase and FpGalactosaminidase, achieving the successful elimination of the blood group A antigen, with an efficiency of 97%, and without any changes in lung health.
In addition, in a simulation of what a transplant of the treated lungs would look like, through an experiment that imitated the conditions of an incompatible transplant, the researchers verified that the lungs did not show signs of immunological rejection.
This development is therefore promising. The efficacy and safety of this approach remain to be seen in clinical trials, which are expected to start in a year and a half. If successful, this technology would allow for greater equity in the allocation of organs for transplantation and potentially save more lives.
It should be emphasized that it is not a technique that generates more organs for transplantation, but rather that it would enable a direct and efficient allocation of the available organs. Parallel strategies to increase the number of available organs, such as xenotransplantation or technical means to maintain and even improve the status of donated organs, must continue, along with bioethical reflection on the dilemmas associated with organ transplantation.
Lucía Gómez Tatay
Bioethics Observatory – Institute of Life Sciences
Catholic University of Valencia