Cell Culture and Fluid Flow conditions

Human MSCs (Lonza Inc.) were cultured in human MSC growth medium (Lonza Inc.) supplemented with 1% penicillin/streptomycin (Invitrogen). Experiments were performed using passages 1–5 of cells. Channels were coated with 50 μg/ml Fibronectin (Sigma-Aldrich Co. LLC) for 1 hour, washed with PBS (1X; Phosphate Buffer Saline) and then 1000 cells/cm² were seeded inside the channels.

For flow experiments, osteogenic medium (Dulbecco’s Minimum Essential Medium (DMEM)), added with 10% fetal bovine serum (Invitrogen), 1% penicillin/streptomycin (Invitrogen), 5 mM β- glycerophosphoric acid (Sigma-Aldrich Co. LLC), 10⁻² μM Dexamethasone (Sigma-Aldrich Co. LLC), and 50 μg/ml L-ascorbic acid (Sigma-Aldrich) was used.

Pa fluid shear stress was applied on cells seeded in these topographical microfluidic channels after calibrating the flow conditions. A peristaltic pump (Model P720; Instech) was used to apply laminar fluid flow on cells. A reservoir of culture medium was attached to the peristaltic pump which was attached to a bubble trap and dampener on the other end. This entire setup was connected to the microfluidic chamber inlet. The chamber outlet was connected to the reservoir to form a closed loop of the flowing fluid. This microfluidic setup (except peristaltic pump) was placed inside an incubator (37 °C and 5% CO₂) (Fig. S2B).