A method of preparing adipose tissue for transplantation from lobular fat material extracted from a body by liposuction, said fat material comprising a fluid component comprising one or more of an oily component, a blood component and sterile solutions, and a solid component comprising tissue fragments and one or more cell macroagglomerates of heterogeneous size, said method comprising - providing a device composed of at least one washing and separating container having a washing chamber for washing the liposuctioned fat material, which container has an inlet and an outlet for the liposuctioned material to enter the washing chamber through the inlet and for at least part of said material to exit said washing chamber through the outlet; said washing chamber including means for mechanically forming an emulsion of fluid components; - exhausting air from the washing and separating container and filling the whole inner volume of the washing and separating container with a sterile washing solution; - injecting the liposuctioned fat material into the washing chamber of the container through the inlet; - forming an emulsion of the fluid component, on which the solid component floats separate from the fluid component, by manual or mechanical stirring of said washing and separating container, so allowing the fluid component to remain separate from the solid component without the use of enzymes or chemicals; - moving the washing and separating container in vertical position so that the different densities of the solid component and the fluid component creates one solid layer of cells and cell fragments floating on the emulsion of the fluid component; - washing the solid component and separating the fluid component, in emulsion form, from the solid component, wherein said washing and separating steps are carried out at the same time, and wherein said washing and separating steps include: - pressure injection of a washing solution into said washing chamber to obtain a high-purity cell agglomerate; - discharging the emulsion of the fluid component from the washing chamber through the outlet of the washing and separating container, wherein said discharge of the emulsion is obtained through a density gradient, following a flow of the liquids from the inlet to the outlet, wherein said discharge of the emulsion of the fluid component is obtained by the flow of the washing solution caused by gravity, which allows removal of the fluid component though said density gradient. - providing a device composed of at least one washing and separating container having a washing chamber for washing the liposuctioned fat material, which container has an inlet and an outlet for the liposuctioned material to enter the washing chamber through the inlet and for at least part of said material to exit said washing chamber through the outlet; said washing chamber including means for mechanically forming an emulsion of fluid components; - exhausting air from the washing and separating container and filling the whole inner volume of the washing and separating container with a sterile washing solution; - injecting the liposuctioned fat material into the washing chamber of the container through the inlet; - forming an emulsion of the fluid component, on which the solid component floats separate from the fluid component, by manual or mechanical stirring of said washing and separating container, so allowing the fluid component to remain separate from the solid component without the use of enzymes or chemicals; - moving the washing and separating container in vertical position so that the different densities of the solid component and the fluid component creates one solid layer of cells and cell fragments floating on the emulsion of the fluid component; - washing the solid component and separating the fluid component, in emulsion form, from the solid component, wherein said washing and separating steps are carried out at the same time, and wherein said washing and separating steps include: - pressure injection of a washing solution into said washing chamber to obtain a high-purity cell agglomerate; - discharging the emulsion of the fluid component from the washing chamber through the outlet of the washing and separating container, wherein said discharge of the emulsion is obtained through a density gradient, following a flow of the liquids from the inlet to the outlet, wherein said discharge of the emulsion of the fluid component is obtained by the flow of the washing solution caused by gravity, which allows removal of the fluid component though said density gradient.