Fig. 3: (A) The obtained viability of the MSCs cultured on the collagen thin films with various concentrations after 48 h; (B) Results of counting the number of MSCs on the collagen thin films with various concentrations after 48 h. Symbol * represents statistically significant between groups determined by ANOVA (p < 0.05).
Bioimpedance assessment of the collagen thin films concentration on the MSCs proliferation rate
3.2.1 Bioimpedance magnitude of the MSCs cells cultured on the collagen thin film
Fig. 4 (A-C) shows the magnitude diagram of the measured impedances of the MSCs seeded on the collagen thin films with various concentrations during the time. As shown in the diagram, the magnitude of the measured differential bioimpedance () at different concentrations of collagen thin films has increased over time. This increase in impedance can be due to cell attachment and proliferation over time. The diagram of the of the MSCs cultured on different concentrations of collagen thin films after 48 h is shown in Fig. 5 (A). Results showed that after 48 h, when the doubling time of the MSCs has elapsed, the amount of increase in impedance at lower concentrations is higher than that of higher concentrations, which may indicate more cell growth on the collagen thin films with lower concentration. Previous studies have investigated the relationship between the collagen thin films concentration and cell proliferation and morphology [2]–[6], [8], [40]. The cells that interact with fibrils formed from higher concentrations of collagen solution do not spread much on the surface and show a weaker cytoskeleton than the cells that interact with fibrils formed from lower concentrations of the collagen thin films. The cells on the surfaces prepared from low collagen concentrations have a higher rate of proliferation and show variations in gene expression compared to the cells on collagen with similar concentrations to the physiological condition [41]. The important point of this research is that we have concluded this result with a quantitative impedance criterion. The same results obtained for HUVECs cells under similar conditions, which will represent in the next section.