Dermal adipocytes and hair cycling: is spatial heterogeneity a characteristic feature of the dermal adipose tissue depot?

Abstract

Adipocytes are widely distributed in the dermis, in a unique fat depot referred to as dermal white adipose tissue (dWAT). In rodents, dWAT is present as widespread thin layers, whereas in pigs and humans it is present in clusters referred to as “dermal cones” around the pilosebaceous units. This distinct layer of fat cells located above the subcutaneous white adipose tissue is important for proper hair follicle (HF) cycling in rodents. Murine HFs produce spatially restricted synchronous patches after their second postnatal cycle which correlates with a spatial heterogeneity of murine dWAT. Similarly, the cycling of HFs in humans may also be related to the spatial distribution of dWAT, making the difference between murine and human HF cycling of more quantitative than of qualitative nature. This should allow the production of small spatially correlated HF patches in human skin and we propose that this process can be regulated by paracrine signaling and involving a number of signaling modules, including the hedgehog pathway. This pathway is an established player in HF cycling, but is also involved in the regulation of adipogenesis and may therefore be a key regulator of the process across species. We also suggest that the spatial heterogeneity of dWAT is connected not only to HF cycling, but may also be related to other physiological and pathological processes in the skin.

Higher plasma leptin is associated with higher risk of androgenetic alopecia in men

“…[7] The interaction between dermal adipose tissue and hair follicles is receiving more attention currently. [8][9][10][11][12] It is known that dermal adipose-derived factors, including leptin, regulate hair cycle propagation and the growth of hair follicles. [4,5,13] However, the impact of leptin on human hair follicles remains unclear.…”

Skin aging: are adipocytes the next target?

“…Similarly, UVR (6 weeks, 3 times weekly, minimal erythemal dose) of the 8-week-old HR-1 hairless mice with the wavelengths of 274-380 nm provided significant increase in the thickness and cellularity of dWAT [79]. These results demonstrate a qualitative difference in modification of dWAT structure in C57BL/6J and different models of hairless mice, but they will need to be re-approved taking into account the spatial heterogeneity of dWAT described in [32]. …”

A novel and robust method for testing bimodality and characterizing porcine adipocytes of adipose tissue of 5 purebred lines of pig

“…To identify these stem cells, certain cell-specific markers would need to be applied to characterize the stem cells that contain no lipid; however, that was beyond the scope of this study. Finally, the outer layer of subcutaneous back fat contains a potentially confounding additional depot, which is those adipocytes around the hair follicles that are physiologically distinct from other subcutaneous adipose tissue 27 . Although every effort was made to exclude hair follicles from the adipose tissue used for this study, the possibility remains that some of these physiologically distinct adipocytes also were included in the analysis and therefore the full extent of depot influence must be considered in this type of study.…”