Abstract: A kit for preparing a composition including fat cells includes: a) at least one sterile tube (1) adapted to be centrifuged, including a body (11) and a plug (12) including an element made of elastic and retractable material, the body (11) being hermetically sealed by the plug (12), the plug (12) including an air outlet (13) provided with a filter membrane having a size of pores of less than 0.30 ?m; and b) at least one sterile needle including a central channel, one end of which is provided with a device for being fixed to a syringe, and the other end of which is bevelled, the diameter of the central channel being not less than 3 millimeters, preferably not less than 5 millimeters.