title: Intravital microscopy of localized stem cell delivery using microbubbles and acoustic radiation force.
abstract: The use of stem cells for the repair of damaged cardiac tissue after a myocardial infarction holds great promise. However, a common finding in experimental studies is the low number of cells delivered at the area at risk. To improve the delivery, we are currently investigating a novel delivery platform in which stem cells are conjugated with targeted microbubbles, creating echogenic complexes dubbed StemBells. These StemBells vibrate in response to incoming ultrasound waves making them susceptible to acoustic radiation force. The acoustic force can then be employed to propel circulating StemBells from the centerline of the vessel to the wall, facilitating localized stem cell delivery. In this study, we investigate the feasibility of manipulating StemBells acoustically in vivo after injection using a chicken embryo model. Bare stem cells or unsaturated stem cells (<5 bubbles/cell) do not respond to ultrasound application (1 MHz, peak negative acoustical pressure P_ = 200 kPa, 10% duty cycle). However, stem cells which are fully saturated with targeted microbubbles (>30 bubbles/cell) can be propelled toward and arrested at the vessel wall. The mean translational velocities measured are 61 and 177 μm/s for P- = 200 and 450 kPa, respectively. This technique therefore offers potential for enhanced and well-controlled stem cell delivery for improved cardiac repair after a myocardial infarction.
authors.affiliation: Biomedical Engineering, Thorax Center, Erasmus Medical Center, Rotterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands. t.kokhuis@erasmusmc.nl.
authors.forename: T J A
authors.initials: TJ
authors.lastname: Kokhuis
authors.forename: I
authors.initials: I
authors.lastname: Skachkov
authors.forename: B A
authors.initials: BA
authors.lastname: Naaijkens
authors.forename: L J M
authors.initials: LJ
authors.lastname: Juffermans
authors.forename: O
authors.initials: O
authors.lastname: Kamp
authors.forename: K
authors.initials: K
authors.lastname: Kooiman
authors.forename: A F W
authors.initials: AF
authors.lastname: van der Steen
authors.forename: M
authors.initials: M
authors.lastname: Versluis
authors.forename: N
authors.initials: N
authors.lastname: de Jong
mesh_terms: D000162:Acoustics; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D006801:Humans; D045164:Mesenchymal Stem Cell Transplantation; D045423:Microbubbles; D008853:Microscopy / Q000379:methods*; D013234:Stem Cells / Q000166:cytology*
keywords: StemBell; acoustic radiation force; mesenchymal stem cell; microbubble; stem cell delivery; ultrasound