Preadipocytes

Preadipocytes are adipose tissue–resident progenitor cells committed to the adipocyte lineage. They originate from mesenchymal progenitors within the stromal-vascular fraction of white adipose tissue and persist after birth, enabling the expansion of adipose depots through the formation of new adipocytes when required.

In vivo, preadipocytes can proliferate and differentiate into mature adipocytes through a process called adipogenesis. Differentiation is driven by hormonal cues such as insulin and glucocorticoids and by cyclic AMP signaling, with central roles for transcription factors PPAR-γ and C/EBPα. Early stages involve C/EBPβ and C/EBPδ, while the mature adipocyte phenotype is accompanied by expression of markers such as adiponectin, FABP4, and perilipin. The transition is accompanied by downregulation of differentiation inhibitors such as Pref-1 (DLK1).

Preadipocytes are enriched in the stromal-vascular fraction of adipose tissue and can be identified by a combination of surface markers. Commonly described markers include PDGFRα, CD34, Sca-1, and CD29, whereas hematopoietic and endothelial markers such as CD45 and CD31 are absent. Pref-1/DLK1 is a marker of early preadipocytes and is typically downregulated as cells commit to adipogenesis.

Clinical and physiological relevance: adipose tissue expands by both hyperplasia (increase in cell number) and hypertrophy (increase in cell size). The balance between preadipocyte proliferation and differentiation influences metabolic health; impaired adipogenesis can contribute to adipose tissue dysfunction, ectopic lipid deposition, and insulin resistance. Preadipocytes are also of interest for regenerative medicine and adipose tissue engineering.