Joris van Dongen

13 General introduction and outline of the thesis Lipoaspirate directly after injection Lipoaspirate after several weeks after injection Lipoaspirate after several months after injection Old adipocyte Adipose derived stromal cell Newly formed adipocyte Fibrotic tissue 1. 2. 3. 2. 1. 3. Necrotic zone Regeneration zone Peripheral zone Legend Fibroblast Blood vessel Figure 1. Schematic overview of the fate of lipoaspirate after injection based on a combination of the host cell replacement theory and cell survival theory. Lipoaspirate contains three zones: peripheral zone (almost all adipocytes and adipose derived stromal cells survive), regeneration zone (most adipocytes die but are replaced by newly formed small adipocytes induced by surviving adipose derived stromal cells) and necrotic zone (all adipocytes and adipose derived stromal cells die and are replaced by fibrotic tissue or absorbed).