Three-dimensional (3D) organoid cell cultures present new opportunities to improve understanding of common reproductive pathologies in the bitch in a laboratory setting rather than using live animals for research. This is an improvement on using research dogs by: i) addressing important welfare and ethical concerns, ii) allowing more controlled study of cellular responses due to different hormones and infectious agents, and iii) permitting high-throughput evaluation of treatments performed in tandem. This 3D reproductive organoid cell culture technology has not been attempted in canines prior to these studies.
Thus far, we have demonstrated that organoids can be generated from canine endometrial tissue, which is the inner layer of the uterus. The tissues were collected from discarded reproductive tracts after a neutering surgery was performed at a local spay/neuter clinic. The organoids were grown for a total of 26 days in culture and maintained normal viable function and structure during this time. This long period of culture whilst maintaining physiologically viable cells is not possible using other traditional cell culture models. For the final 6 days in culture, organoids were exposed to hormonal treatments (i.e., estrogen and progesterone) to mimic what occurs during the reproductive cycle in the bitch.
We found that the canine endometrial organoids are structurally similar to endometrial organoids that have been developed in humans and horses. However, uniquely, canine endometrial organoids demonstrated color, morphology, and gene changes in response to each hormone treatment. Remarkably, these changes mirror the normal physiological processes that occur during the reproductive cycle in bitches. A manuscript is currently being prepared for publication in the Biology of Reproduction Journal.
Afterwards, an additional experiment will be performed that will involve inflammatory stimulation of both healthy and diseased endometrial organoids to mimic endometritis in the bitch, which causes infertility and can lead to the development of life-threatening pyometra. In addition to this experiment, we will also investigate the potential efficacy of a novel therapeutic derived from stem cells in our stimulated canine endometrial organoid model to see if we can reduce or even prevent canine endometrial inflammation. Our goal is to improve the fertility of older bitches that are affected by age-related degenerative changes to their uterus that predispose them to developing endometritis and pyometra.