Reacción a "For the first time, pig kidneys modified with human renal organoids are transplanted into pigs"

The kidneys are essential organs responsible for filtering between 150 and 180 liters of blood per day, eliminating waste products and maintaining the body's balance of water, salts, and minerals. In the context of transplantation, pathologists assess organ viability using the Banff Score, a system that systematically evaluates all areas of the kidney—glomeruli, tubules, interstitium, inflammation, and vessels—before implantation. This is done through a frozen section histopathological analysis of a renal cortex wedge approximately 1 centimeter in size. This histological analysis allows us to determine the degree of chronic damage and establish whether the organ is suitable for transplantation. When the Banff Score is high, primarily due to glomerular sclerosis, tubular atrophy, or vascular damage, the organ is usually considered non-viable. In this scenario, a technology capable of repairing or regenerating renal tissue before implantation could have an enormous clinical impact.

The article published in Nature Biomedical Engineering is a high-quality and experimentally rigorous work that presents a significant advance in regenerative medicine applied to kidney transplantation. It demonstrates that it is possible to infuse human kidney organoids into live porcine kidneys and, using normothermic perfusion, reimplant them in the same animal without known pathology, verifying that the human cells remain viable and integrated, without causing rejection or significant tissue damage. The research stands out for offering a scalable and reproducible method to generate thousands of organoids, which opens the door to conditioning organs ex vivo before transplantation.

From a pathological and clinical perspective, this approach could, in the future, improve the quality of kidneys with a high Banff score, prolong the lifespan of grafts, and reduce the number of discarded organs. However, this has not yet been experimentally demonstrated, and there is no evidence that the organoids can participate in repair or connect to the afferent and efferent arterioles necessary to restore filtering function.

The work, therefore, has enormous value as a proof of concept, but its results should be interpreted with caution. The experiments were performed on seven perfused kidneys, with follow-up limited to 48 hours, so the long-term effects and the immunological or proliferative behavior of the human cells over longer periods are still unknown. After the transplants, the animals were sacrificed, and a detailed histopathological analysis of the reimplanted kidneys was performed, but not a complete autopsy that would have allowed for the identification of possible cell dissemination to other organs. Although no complications were observed, questions remain regarding possible microemboli, local inflammation, or uncontrolled cell proliferation that could lead to tumors in the long term.

Overall, this is a solid, innovative, and well-designed article that points in a promising direction at the frontier between bioengineering and kidney transplantation, although it is still in an early experimental phase. If further studies confirm its safety and efficacy, it could open the door to regenerative strategies capable of recovering damaged organs and facilitating their use in human transplantation.