Page 86 - Cellular Imaging in Regenerative Medicine, Cancer and Osteoarthritis

Chapter 4
Results
Microbubble dynamics
During all studied ultrasound bursts, we observed displacement and disappearance of tMB. This was most pronounced for the 30 s insonification period, as shown in Fig 2. During insonification, tMB also clustered (Figs 2B-D). After the 30 s insonification period, no tMB were observed in the field of view (Fig 2E), suggesting they had been destroyed.
Figure 2 Optical recording of tMB on HUVECs during ultrasound treatment. A before treatment. B-E tMB displacement, clustering, and destroyment during 30 s insonification (1MHz, 80 kPa PNP, 10,000 cycles, repetition rate of 20 Hz, 30 s insonification treatment, SPIO added at -5 min with respect to the start of insonification).
Insonification duration
In the absence of ultrasound, less than 2% of cells intracellularly incorporated SPIO naturally (Fig 3A). The efficacy of SPIO uptake by HUVECs and the corresponding cell viability as a function of the acoustic PNP and the total insonification duration (1, 10, or 30 s) at low MI (<0.16) are shown in Fig 3. The total ultrasound exposure time was a key factor for SPIO uptake efficacy. This was demonstrated by the amount of SPIO positive cells not exceeding 4% for 1 s and 6% for 10 s of insonification, but with 30 s of insonification the amount of SPIO positive cells increased to more than 10%. Additionally, the PNP also influenced SPIO uptake significantly. With 30 s of insonification, the proportion of SPIO positive cells significantly increased with the PNP (i.e., from
84