The invention provides freeze-dried nucleated cells, a method for preparing them, and methods of using them for in vitro assays and in vivo therapeutic treatments. The method for preparing the cells includes incubating cells in the presence of a cryoprotective sugar to load them with the sugar, then lyophilizing them without separating the cells from the cryoprotective sugar. In embodiments, the cells are also loaded with one or more bioactive agents.