Low-intensity pulsed ultrasound enhances neurite growth in serum-starved human neuroblastoma cells
Xuanjie Ye, Zitong Wang, Rebekah van Bruggen, Xin-Min Li, Yanbo Zhang, Jie Chen
Frontiers in Neuroscience 2023, 17 · 10.3389/fnins.2023.1269267
Abstract
Introduction Low-intensity pulsed ultrasound (LIPUS) is a recognized tool for promoting nerve regeneration and repair; however, the intracellular mechanisms of LIPUS stimulation remain underexplored. Method The present study delves into the effects of varying LIPUS parameters, namely duty cycle, spatial average-temporal average (SATA) intensity, and ultrasound amplitude, on the therapeutic efficacy using SK-N-SH cells cultured in serum-starved conditions. Four distinct LIPUS settings were employed: (A) 50 mW/cm 2 , 40%, (B) 25 mW/cm 2 , 10%, (C) 50 mW/cm 2 , 20%, and (D) 25 mW/cm 2 , 10%. Results Immunochemistry analysis exhibited neurite outgrowth promotion in all LIPUS-treated groups except for Group D. Further, LIPUS treatment was found to successfully promote brain-derived neurotrophic factor (BDNF) expression and enhance the phosphorylation of extracellular signal-regulated kinase (ERK)1/2, protein kinase B (Akt), and mammalian target of rapamycin (mTOR) signaling pathways, as evidenced by western blot analysis. Discussion The study suggests that the parameter combination of LIPUS determines the therapeutic efficacy of LIPUS. Future investigations should aim to optimize these parameters for different cell types and settings and delve deeper into the cellular response mechanism to LIPUS treatment. Such advancements may aid in tailoring LIPUS treatment strategies to specific therapeutic needs.
Abstract via europepmc.
Exposures
Exposure 1: LIPUS stimulation of serum-starved SK-N-SH neuroblastoma cells (Groups A-D)
Target: other — “SK-N-SH human neuroblastoma cells (serum-starved, in vitro)”
Device: custom-built
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,500 | ✓✓✓ |
| Pulse duration (ms) | not reported | ⚑ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 40, 20, 20, 10swept | ✓✓✓⚑ |
| Sonication duration (s) | 600 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 0.025, 0.05swept | ✓✓✓ |
| In-situ estimate | not applicable | |
| In-situ pressure (kPa) | not applicable | |
| In-situ Isppa (W/cm²) | not applicable | |
| In-situ Ispta (W/cm²) | not applicable |
Four LIPUS parameter configurations (A: 50 mW/cm2 SATA/40% DC; B: 25 mW/cm2/20% DC; C: 50 mW/cm2/20% DC; D: 25 mW/cm2/10% DC), UFF 1.5 MHz and PRF 1 kHz held constant, were applied to serum-starved (1% FBS) SK-N-SH cells for 10 min/day (transducer rotated 180 degrees after the first 5 min) for 4 consecutive days, compared against a serum-starved control and a healthy (10% FBS) control receiving no LIPUS.
Flags from extraction
exposures[0].unspecified_domain.ispta_w_cm2— Paper reports 'spatial average-temporal average (SATA)' intensity, not spatial-peak temporal-average (ISPTA); recorded here as the closest available field, but SATA is a spatially-averaged (not spatial-peak) quantity so the two are not equivalent.exposures[0].timing.duty_cycle_pct— The abstract lists group B and D duty cycles both as 10%, inconsistent with the Methods (section 2.3) and Discussion, which both give group B as 20% duty cycle; the Methods/Discussion values (40, 20, 20, 10 for A-D) are used here as the more detailed and internally consistent source.exposures[0].timing.pulse_duration_ms— Only duty cycle and PRF are stated; pulse duration is not given directly and was not computed from these per instructions.n_subjects— N=5 is the replicate count reported for the LDH and western blot assays; a different N=250 is reported for neurite-length/soma-width quantification (likely a cell count rather than a replicate/culture count), so a single 'n_subjects' is ambiguous across assays.