Human Bone Marrow Contains Mesenchymal Stromal Stem Cells That Differentiate In Vitro into Contractile Myofibroblasts Controlling T Lymphocyte Proliferation

Figure 5

Row data of membrane contractility. Membrane tension is expressed in mN/mm²; Li is the membrane length at resting basal tone; time is expressed in seconds (s). (a) Membrane length and tension variations are registered after successive increments by 0.1 mN loading steps, and are shown as a function of time. Upper panel: length increase (note that the scale is inverted in the vertical axis). Lower panel: tension increase. (b) Computation of the Young modulus using the data generated in (a). The membrane in this example is an empty membrane and its Young modulus is 450 Pa. (c) Effect of 50 mM KCl on a MSC-laden membrane. Upper panel: membrane shortening (note that the scale is inverted in the vertical axis on this plot: if membrane shortening increases, membrane length decreases). Lower panel: tension generation. The vertical arrow pointing downwards identifies the time point where tension was suddenly increased, shifting the system from isotonic mode to isometric mode. The active tension amplitude equals the total tension represented by the gray dotted line minus the basal tone, which is the lower solid black horizontal profile generated during the isotonic mode. (d) Relaxation of the membrane previously stimulated by KCl by ISDN (NO donor). Upper panel: membrane lengthening; lower panel: tension observed after the exposure to lSDN. Similar contractile parameters were observed with MSC-laden membranes stimulated by an electric tetanus. These data are representative of 23 experiments for empty membranes and 25 experiments for MSC-laden membranes for the Young modulus determination, 9 and 17 for KCl and tetanus stimulations, respectively, and 10 for ISDN relaxation and 9 for BDM relaxation (see Table 2).

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