Altered Adipose-Derived Stem Cell Characteristics in Macrodactyly

Macrodactyly is a congenital disease characterized by aggressive overgrowth of adipose tissue in digits or limbs frequently accompanied with hyperostosis and nerve enlargement; its pathological mechanism is poorly understood. Adipose-derived stem cells (ASCs) have been extensively studied in tissue engineering and regenerative medicine as an ideal alternative substitute for bone marrow-derived mesenchymal stem cells (BM-MSCs), but their pathological role is largely unknown. In this study, ASCs from macrodactyly adipose tissues (Mac-ASCs) were isolated and compared to ASCs derived from the normal abdominal subcutaneous adipose tissue (Sat-ASCs) for cell morphology, surface marker expression, proliferation rate, and tri-lineage differentiation potential. Despite similar cell morphology and cell surface marker expression, Mac-ASCs showed higher cell proportion in the S phase and increased proliferation compared with Sat-ASCs. Moreover, osteogenic and chondrogenic differentiation capacities were enhanced in Mac-ASCs, with reduced adipogenic potential. In addition, the expression levels of adipogenic genes were lower in undifferentiated Mac-ASCs than in Sat-ASCs. These findings unraveled enhanced proliferation activity, a regression in the differentiation stage, and greater potentiality of ASCs in macrodactyly, which could contribute to hyperostosis and nerve enlargement in addition to adipose tissue overgrowth in patients.