Stochastic modeling of adipogenesis in 3T3-L1 cultures to determine probabilities of events in the cell's life cycle.

3T3-L1 preadipocytes are often being used in research of adipose-related diseases such as obesity, insulin resistance, and hyperlipidemia. We developed a stochastic model that simulated differentiation of four 3T3-L1 culture conditions distinct by the insulin concentration in the differentiation medium (2.5, 5, 7.5, or 10 μg/mL). The model simulated culture behavior and the accumulation of lipid droplets in the maturing cells from the day of induction of differentiation through 28 days after that. The cellular processes including cell adhesion, mitosis, growing after undergoing mitosis, commitment to the adipocyte lineage, and apoptosis were referred to as stochastic events in the modeling. By minimizing the error between our model and experimental results, we found that the probability for becoming committed to the adipocyte lineage in a single division and the probability for growing after undergoing mitosis were 0.02 and 0.8, respectively, regardless of the insulin concentration. The probability for undergoing mitosis was equal to 0.2 and 0.4 in cultures that had insulin concentrations of 2.5 and 5-10 μg/mL in the differentiation medium, respectively; hence the insulin concentration affected the probability for mitosis in the 3T3-L1 cells. The model and resulted probabilities now allow quantitative and visual predictions of adipogenesis in 3T3-L1 cultures, toward computational design of cell culturing protocols.