Forsøksdyr: In vivo real time imaging of extravasation of nanoparticles induced by novel microbubbles


Godkjenningsdato 18.11.2020

Godkjenningsperiode 01.12.2020-30.11.2024

Purpose
Delivery of drugs and nanoparticles to solid tumours is currently challenging. Fortunately, delivery can be improved by using microbubbles combined with ultrasound which increases the permeability of tumour vasculature thereby improving the delivery of the co-injected drug. Currently, mainly microbubbles of which their properties were optimized for diagnostic imaging purposes are used for ultrasound-mediated drug delivery to tumours. To improve the efficiency of ultrasound-mediated drug delivery, new type microbubbles are needed which exhibit properties more favourable for therapy purposes. In the experiments described here, a novel microbubble will be used which has several advantages over conventionally used microbubbles and has already shown great potential in improving drug delivery to solid tumours such that a clinical trial is initiated in 2021. However, the mechanism behind the improved delivery induced by this novel microbubble is not fully understood. The experiments described will help to unravel the mechanism and will thereby help to optimize treatments with this microbubble.
For these experiments, a tumour will be grown in a window chamber on the back of the mouse which will make it possible to treat the tumour with ultrasound and the novel microbubbles while imaging simultaneously with a multiphoton microscope. Fluorescently labelled Dextrans and/or nanoparticles will be co-injected to visualize the vasculature and study the microbubble location and induced extravasation of the co-injected agents. We will be able to image this in real time, in vivo and with high spatial and temporal resolution. The results achieved with these novel microbubbles will be compared to those obtained when using SonoVue microbubbles, which is one of the most commonly used microbubbles in ultrasound-mediated drug delivery.

Distress
We have performed similar studies in the past and expect the animals to have moderate distress. Based on previous experience, animals were behaving normally the days after implantation of the dorsal window chamber. Animals showed normal drink, eat and sleep behaviour, and did not loose weight. Animals will be monitored on a daily basis and will receive proper (post) surgery care consisting of anaesthesia, analgesia and antibiotics.

Expected benefit
The study will help us to unravel the mechanism behind the improved delivery of drugs and nanoparticles induced by the microbubbles. In previous preclinical work, the microbubbles showed great therapeutic potential and clinical trials will therefore be initiated in 2021. The results of the experiments described in this application will help to understand the in vivo behaviour of the novel microbubbles and will help with optimizing future treatments with these microbubbles.

Number of animals
A total of 40 male Balb/c mice will be used in the study presented here.

How to adhere to 3R
Animals will be anaesthetized during all procedures and receive pain medication during and after the surgical procedure. The body temperature of the animals will be maintained with heating pads and heating lamp. Eyes will keep moist with eye drops and respiration rate will be closely monitored. Mice will be euthanized by cervical dislocation which is fast and ensures death.