Is it possible to have an animal to human organ transplant? 

Transplanting animal organs into humans has been in the works for centuries.

The transplantation of animal organ, tissues or cell across species is called Xenotransplantation.

Tissue xenotransplants have been carried out as early as the 17th to 18th century when blood was transfused into human patients with mixed results.

In 1838, the first corneal xenotransplantation (from a pig) was performed in a patient, whereas the first corneal allograft (human-to-human) was not carried out until more than 65 years later, in 1905.

China has reportedly performed more than 400 corneal xenotransplants since 2015 when it was approved.

Organ xenotransplantation has actually been performed as far back as the early 20th century when a French surgeon implanted a pig kidney and a goats liver in his human patients, they didn't survive, It'd have been a miracle if they did.

In 1963, chimpanzee kidneys were transplanted into 13 patients. It's reported one of them actually survived for 9 months before dying of what was believed to be electrolyte disturbance. Probably organ rejection.

In 1964, Hardy carried out the first xeno heart transplant using a chimpanzee heart but the patient died within 2 hours.

In 1966, Starlz transplanted the first chimpanzee liver into a human. By 1992 his patient was able to survive for 70 days following a baboon liver transplant.

Baboons and Chimpanzees are a favoured donor because of the close genetic relatedness we share. They are hardy virus carriers and there have been ethical concerns regarding their use.

Pigs are the next favourite, their anatomy is similar to that of humans and are generally healthier than baboons. Genetically modified pigs offer a hope of limitless supply of blood and organs for those in need.

Xenotransplant procedures are still experimental presently and the main risk to the procedure is organ rejection, just as it is for human to human transplants.

However an added risk is the probability of a Zoonotic disease outbreak. Animals carry lots of pathogens, some of which are harmless to them but very harmful to us.

In the nearest future, as early as 5 years, we might have successful xenotransplants with better prognosis than human transplants. Hopefully.