Forsøksdyr: Host immune recognition, response, and elimination of nanoparticles

Godkjenningsdato 12.08.2020

Godkjenningsperiode 12.08.2020-11.08.2024

1. Purpose
Nanoparticles hold large opportunities in medicine. The nanoparticles of 10-100 nm can be designed as carriers for site-specific delivery. In the ideal situation, the nanoparticles should reach targeted sites, e.g. cancerous tumors, and deliver their loadings with high therapeutic efficiency and low adverse systemic effects. However, this ideal situation is counteracted by the rapid systemic elimination of nanoparticles once the nanoparticles are in contact with blood. Our purposes in this proposal are: i) to evaluate the impacts of nanoparticles on protein cascades of complement and coagulation system in vivo, (ii) to evaluate the responses of immune cells upon encountering the nanoparticles, and iii) to identify the clearance pathway of the nanoparticles from the bloodstream.

2. Distress
The animal will primarily experience distress from intravenous injection of nanoparticles and possibly low immune reaction to nanoparticles. Overall, the distress will be low.

3. Expected benefit
The knowledge of how nanoparticles are recognized and eliminated is still limited. We have gained a lot of understanding by using human whole blood in vitro in the short term (up to 4 hours). By continuing in the in vivo model, we will be able to increase our knowledge what happens in the long-term (up to 96 hours). This is crucial for the design of nanoparticles that can overcome immune recognition and rapid elimination in the bloodstream.

4. Number of animals, and what kind
We apply for 780 animals (over 4 years), including mice of wild type, single knock-outs for C3 or CD14, and double knock-out for C3 and CD14

5. How to adhere to 3R
Replace: We have made thorough investigations in vitro by using human blood donated from healthy donors. We have now reached the limit of this model based on three things: 1) In vitro human blood needs to be anticoagulated and the anticoagulant used interferes the immune responses; 2) The human whole blood model can be used for a maximum of 4 hours after that pH and glucose levels are altered significantly from the physiological environment. 3) The whole blood model cannot give us information about the tissue distribution of nanoparticles.

Reduce: We are using a minimum number of animals per group (n=8) which is a reasonable number to be able to draw conclusions from biological relevant differences. With fewer animals, we are afraid to take the risk of having statistical power to draw conclusions of the observations.

Refine: The mice are handled by the same trained researchers, assuming to reduce stress. We will follow well-established methods regarding nanoparticle administration. Mice will be euthanized if they reach humane endpoints, which is not to be expected. We follow the guidelines for housing and environmental enrichment applicable to our department.