Reacción a "First pig-to-human liver transplant evaluated"

I thought it was a very important piece of work, but we have to be cautious. The study represents a milestone in the history of liver xenotransplantation, as it is the first time that a transplant of a genetically modified pig liver into a human being (in this case, a brain-dead patient) has been described.

The quality of the work is very high, both in terms of scientific rigour and the exhaustive clinical, immunological, histological and haemodynamic characterisation of the procedure. Sophisticated genetic modifications have been applied to the graft to prevent hyperacute rejection, one of the most critical complications in preclinical xenotransplantation models.

The clinical implications are highly relevant, as optimising this approach could expand the pool of available organs and save lives in liver emergencies. This work complements and expands the existing evidence on previous xenotransplants of pig hearts and kidneys into humans. It contributes several relevant new findings:

• It is the first study to demonstrate that a genetically modified porcine liver can survive and carry out basic metabolic functions (production of albumin and bile) in the human body.
• It shows that there was no significant coagulation dysfunction, in contrast to what was observed in other models, such as the first human cardiac xenotransplant, where microthrombi and severe disorders were detected.
• It highlights the need to assess possible myocardial damage in the early stages of the postoperative period, given the early elevation of the AST enzyme and cardiac enzymes, something that can be confused with liver damage.
• The use of xenografts as a bridging therapy is proposed, especially in patients with acute liver failure awaiting a human graft, although not as a definitive solution, since bile and albumin production was limited for long-term support.

However, the study has significant limitations:

• An important limitation of the study is that it is a single case (n=1), which prevents generalisable conclusions from being drawn or solid patterns of clinical and immunological response from being established. Although this is a pioneering advance, studies with a larger sample and in living recipients will be necessary to confirm the safety, efficacy and reproducibility of the procedure.
• Limited duration of follow-up (10 days), by decision of the recipient's family, which prevents the viability of the graft from being assessed in the medium and long term. Therefore, it does not add information in relation to acute and chronic rejection of xenotransplants.
• Only basic liver functions were evaluated (albumin synthesis and bile secretion), with no data on other complex liver functions such as drug metabolism, detoxification or immunological function.
• The heterotopic auxiliary transplant procedure would not allow the original liver to be resected, which invalidates it as a strategy for example in patients with hepatocellular carcinoma awaiting transplant.