Final considerations and perspectives
Even though 3D culturing is clearly incapable of replacing other current
research types, they might continue to replace some unnecessary animal
experimentation, as well as improve monolayer cultures. It is not even
recommended or expected that 3D models substitute all other research
types, but in regard to animal testing, they come in hand for the 3 Rs:
Reduction, Refinement, Replacement. The concept, postulated in 1959 by
Russel and Burch, is still very pertinent, and proposes the need for
alternative methods that present at least one of the following:
Reduction in the total number of animals used; Refinement of experiments
that endure pain or suffering; Replacement of experiments that can be
performed without animals with the same representability (Costa et al.,
2018; Kirk, 2018; Russell and Burch, 1959). Both spheroids and organoids
represent, in this way, a further step in replicating organ
characteristics in absence of animal suffering and with small ethic
concerns, and promising candidates as realistic models that will thrive
us to the medicine of the XXI century.