Galvin, M., Lallo, A., Brown, S. et al. 2018. Refinement of tumour passage by optimisation of the tissue disaggregation protocol. Animal Technology and Welfare 17(2), 101-103.

Surgical implantation of tumour pieces has been used regularly in the passage of tumour models. This involves an invasive surgical procedure, carried out under anaesthesia, ensuring mice have adequate pain relief and peri-operative care. The procedure also requires multiple tumour-bearing donor mice to generate sufficient tissue for surgical implantation, particularly for large scale efficacy studies. We sought to refine our tumour passage methods and subsequently reduce the number of mice required for studies by implanting viable, dissociated tumour cells instead of tumour fragments. Tumours are disaggregated and depleted for red blood cells and any dead/residual mouse cells. This allowed the enrichment for human tumour cells that were mixed with Matrigel and implanted subcutaneously in the hind flank of mice. Cell viability was successfully maintained with this method and mice developed tumours. Due to the high number of cells generated using this protocol we are able to implant more mice per tumour, thus reducing the number of donor mice required for large scale efficacy studies. Moreover, subcutaneous injection is a less invasive procedure with a milder severity than surgical implant under general anaesthesia. Not only does this porcess improve animal welfare from a 3Rs' perspective, it also improves other aspects of the experiment by reducing intertumour heterogeneity, thus improving the science.