Research Update CHF 03055 EY1: Evaluating Reproductive Diseases in vitro with a 3D Canine Endometrial Organoid Model

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 under hormonal influence 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 where infection can cause endometritis or life-threatening pus to be produced. This condition is called pyometra.

The tissues in these experiments 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. This long culture time is not possible using other cell culture models while maintaining normal function and structure.

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. Afterwards, an additional experiment will be performed that will involve inflammatory stimulation of the organoids to mimic endometritis in the bitch, which causes infertility and can lead to the development of life-threatening pyometra. In addition, we will trial some novel therapeutics including acellular extracellular vesicles to see if we can prevent infection in the endometrium from occurring.