FIG. 5.

ATP-induced Ca²⁺ signaling in hMSC-EC coculture is affected by the cells' spatial configuration. (A) Examples of a cell exhibiting nonoscillating Ca²⁺ response (i), and a cell exhibiting Ca²⁺ oscillations (ii) in response to 10 μM ATP. The percentage of cells exhibiting Ca²⁺ oscillations varies in the two monocultures and the two different coculture configurations, with the unmixed coculture exhibiting the highest percentage of oscillating cells. (C) The average number of Ca²⁺ spikes in individual cells varies in the two monocultures and the two different coculture configurations, with the highest number of spikes in the mixed cocultures. Values are averages of three experiments and error bars are standard deviations (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001). (D) Distribution of Ca²⁺ oscillation periods in an unmixed hMSC-EC coculture reveals two dominant oscillation period (ii), while an EC monoculture and a mixed hMSC-EC coculture show only one dominant oscillation period (i, iii). Red line indicates modes of distributions. (E) More cells exhibit Ca²⁺ oscillations in an EC monoculture (i) and an unmixed coculture (ii), however, more Ca²⁺ spikes per cell are observed in a mixed coculture (iii). (F) Cross-correlation analysis for Ca²⁺ response of cells in EC monoculture (i), unmixed coculture (ii), and mixed coculture (iii): cellular communication is correlated with a time scale of 16 s for ECs, and 40 s for unmixed EC-MSC coculture, while Ca²⁺ responses in mixed populations show no temporal cross-correlation.