Bone marrow-derived mesenchymal stem cells (i.e., adherent cells) are known to differentiate into fat tissue in the presence of adipogenic supplements in cultures. Induction of adipogenesis has not been investigated within the nonadherent cell fraction that includes predominantly hematopoietic cells. In the present study, murine nonadherent bone marrow-derived stem cells (96% CD45+ cells) were seeded and then grown in fibrin gel to form cell clusters in which most cells were positive to DiI-acetylated low-density lipoprotein uptake. Amongst different culture media supplemented either in fetal bovine serum, horse serum, murine plasma, human plasma or adipogenic supplements, a subpopulation of nonadherent stem cells within clusters differentiated into adipocytes, specifically in the presence of adult syngeneic plasma. This was confirmed by the observation and quantification of oil red O-positive cells, the measurement of glycerol-3-phosphate dehydrogenase activity and peroxisome proliferator-activated receptor-γ mRNA expression. Similarly, adipogenesis was also observed in the presence of murine plasma with adherent mesenchymal stem cells and 3T3-L1 preadipocytes which were grown either in monolayer plastic cultures or in fibrin gel. Thus, it is possible that nonadherent cells, once in a 3-dimensional environment, can further differentiate towards adipogenesis.