Breast tumor microenvironment encompassed by various adipocytes is determining the outcome of recurrence after lipofilling for post-resection breast reconstruction. This study aims to explore the effects from different types of adipocytes as well as the underlying mechanisms. Among all adipocytes, brown adipocyte was identified as the most dangerous adipocyte whereas adipose-derived stem cell was relatively safe. The underlying mechanisms include altered adipogenesis, mitochondrial dysregulation, and most importantly, the formation of cell fusion.