The core of this device is the column incorporating a non-woven filter. When bone marrow fluid is passed through the column, MSCs and some nucleated cells attach themselves to the filter fibre. Red blood cells, which inhibit the proliferation of MSCs during cultivation, simply pass through the filter.
Flushing the cell harvest solution through the column in the direction opposite to the flow of bone marrow fluid washes out the MSCs trapped in the filter inside the column and harvests them.

This is how one collects fluid with high concentrations of MSCs.