What are the advantages of using a pig's heart to create a human heart versus growing a heart directly from stem cells? (this is science btw)

The advantages of the pig's heart over the heart formed by the stem cells is that they come in many size so it is possible to have heart for every age group of people.

There are less chances of rejection as pigs also are mammals and moreover there will be no ethical issues as such because a huge number of pigs are slaughtered everyday for human consumption and if their heart can be used for some beneficial purpose it would be good cause.

The risks related to stem cell transplantation includes tumour formation, rejection of the transplanted stem cells, infection and haemorrhage which can be quite risky for the patients.

It is not that pig's heart is always acceptable but the chances are less as compared to stem cell.