The present invention relates to an in vitro or ex vivo method of preparing a cell-free composition, said method comprising or consisting of (a) subjecting cells to stress and (b) collecting factors produced, preferably secreted by said cells when subjected to said stress, thereby obtaining said cell-free composition wherein said cells are comprised in or form at least one first carrier and said collecting is effected by means of at least one second carrier which second carrier(s) is/are cell-free and concomitantly present with and spatially distinct from said first carrier and said collecting is effected using a device comprising or consisting of (i) said first carrier(s) which first carriers) comprise(s) said cells or is/are suitable to hold said cells (ii) said second carrier(s) which is cell-free and (iii) means of subjecting said cells in said first carrier to stress wherein first carriers) and second carriers) are positioned such that factors secreted by said cells when subjected to stress are collected in said second carrier (s), wherein means are positioned between said first and second carrier which prevent any cells and/or pathogens present in (any of) said first carrier(s) from entering into said second carrier(s).
