Abstract
We previously discovered some adipocytes in the major white fat depots of mice and humans arise from bone marrow-derived cells of hematopoietic lineage rather than conventional mesenchymal precursors, termed bone marrow-derived adipocytes (BMDA). Here we aimed to determine if hematopoietic lineage cells isolated from adipose tissue and circulation of humans could undergo adipogenic differentiation in vitro, thereby establishing an in vitro model for studies of BMDA. We hypothesized that hematopoietic lineage cells isolated from adipose tissue, but not circulation, of humans would demonstrate adipogenic potential. Participants included younger (20-50 years) and older (>50-75 years) men and women, BMI 20-37 kg/m(2). Subcutaneous abdominal adipose tissue biopsies were obtained and stromal cell populations identified by flow cytometry. Sorted cells underwent in vitro cultivation via traditional mesenchymal culture methodology (mesenchymal lineage) or a novel 3D-fibrin clot followed by traditional adherent culture (hematopoietic lineage) for assessment of proliferation and differentiation capacity. We found hematopoietic lineage cells isolated from the adipose tissue stroma, but not the circulation, were capable of proliferation and multilineage (adipogenic and osteogenic) differentiation in vitro. We provide a new investigative tool that can be used to perform translational studies of BMDAs and provide initial evidence that hematopoietic lineage cells isolated from the adipose tissue of humans can undergo hematopoietic-to-mesenchymal transition with multilineage differentiation potential in an in vitro environment.