Fig. 4: In vivo characterization of the FUS-based mechanogenetic system.
From: Tumour priming by ultrasound mechanogenetics for CAR T therapy
a, Schematic of the custom-built FUS stimulation set-up for small animals. A Python-controlled user interface was used to define stimulation patterns and parameters, which directed a function generator and power amplifier to drive the FUS transducer. Temperature changes in the tumour region were monitored by a needle-type thermometer during the 30 min stimulation window. PNP, peak negative pressure. b, Two-dimensional beam profile of the 1 MHz transducer at the focus, measured by hydrophone. c, Temperature recordings at the tumour site during FUS stimulation, showing fluctuations of less than 1 °C. d, Simulated acoustic wave propagation and spatial distribution of mechanical stress in a layered mouse tissue model, including skin (0.5 mm thick), muscle and a 3 × 3 × 1.8 mm3 embedded tumour. e, Experimental design of in vivo activation of the CaDox system by FUS. PC-3-CaDox–NLuc cells were injected into NSG mice to establish a bilateral tumour model. On day 5, tumours were treated with either doxycycline, FUS or both. Bioluminescence imaging (BLI) was used to monitor luciferase intensities over a 24 h period. L, left; R, right; s.c., subcutaneous; IVIS, in vivo imaging system. f, Representative BLI images of gene expression in subcutaneous tumours in response to the treatment with FUS alone or combined doxycycline and FUS. Images are representative of four mice per group. p, photons. g, Quantification of normalized gene expression fold change over time (n = 4 mice per group). Signal intensities were normalized to the untreated control. Error bars indicate s.e.m. Statistical significance was determined using a two-sided paired t-test. Adjusted P values comparing Dox only versus Dox + FUS conditions were as follows: 6 h, P = 0.0098; 12 h, P = 0.0033; and 24 h, P = 0.0003. ** and *** denote adjusted P < 0.01 and P < 0.001, respectively. Panels a, d and e created with BioRender.com.
