Polarity reversal of canine intestinal organoids reduces proliferation and increases cell death

Organoids represent a promising alternative model that should definitely be considered, especially with regard to One-Health concepts and the 3Rs. The polarity reversal of organoids poses a method that enables new approaches to the experimental use of organoids. It can be concluded that the polarity inversion of intestinal organoids significantly affected both apoptosis and proliferation. The process of polarity reversal also proceeded with surprising efficiency. Thus, almost no basal-out organoids could be detected after only 36 to 48 hours. Another unexpected finding was the fact that within one and a half hours of incubation in Organoid Harvesting Solution, the majority of the organoids exhibited apical-out or mixed polarity. The process of the polarity reversal was therefore significantly faster than in prior reports.The basal-out organoids showed constant, if not increasing, proliferation rates, whereas the apical-out organoids, after a short peak in terms of viability, resulted in increasing apoptosis levels and a decreasing cell number. Immunohistochemical staining also confirmed these findings. Marker genes examined by RT-qPCR further showed stable gene expression in basal- and apical-out organoids.