Gestro was the Director of the Natural History Museum of Giacomo Doria Genoa where his collection is conserved.
He became interested in botany under Giuseppe De Notaris and then in zoology thanks to G. Ramorino who was an assistant to Pietro Mansueto Ferrari.
In 1866 he graduated in medicine and volunteered with the Garibaldi medical corps during the third war of independence in Trentino.
Doria returned with large collections which led the city to found a new museum of natural history in 1867.
He was also appointed grand officer of the Crown of Italy and knight of the Order of Gustavus Vasa of Sweden.