New insights could lead to lasting improvement of stem cell therapy in horses

Mesenchymal stem cells are multipotent cells found in a number of tissues that can differentiate into various cell types. Stem cells thus provide an enormous potential for regenerative medicine. Such progenitor cells have been used clinically for about 15 years to treat several tendon and joint conditions in horses.

Until now, the stem cells needed for therapeutic purposes have usually been harvested surgically from the animals' bone marrow or fat tissue. Researchers from the Centre for Artificial Insemination and Embryo Transfer at Vetmeduni Vienna have now succeeded for the first time in harvesting stem cells from the uterus of horses. The procedure requires no surgical intervention and the laboratory results show that the cells differentiate into cartilage and other tissues.

Uterine stem cells harvested without surgery

Unlike bone marrow or fat tissue, the uterus can be accessed non-surgically using small instruments inserted via the cervix. The harvest of mesenchymal stem cells from the endometrium, the mucous membrane of the uterus, could therefore contribute to a reduction of surgical and invasive experiments in animals.

"While the human endometrium is known to harbour stem cells, these had previously not been identified in equine endometrium," say Elisabeth Rink and Christine Aurich from the Centre for Artificial Insemination and Embryo Transfer at Vetmeduni Vienna. The two researchers, in an international team with Xavier Donadeu from the Roslin Institute at the University of Edinburgh and Hilari French from Ross University School of Veterinary Medicine in Saint Kitts and Nevis, have now managed to confirm the presence of stem cells in the endometrial tissue of horses. The data on the isolation, culture and characterization of mesenchymal stem cells from the equine endometrium was published in the journal Stem Cell Research and Therapy.

Extended options for stem cell therapy in horses

For the study, uterine tissue samples were collected from six mares. The team then separated suspected stem cells from endometrial epithelial cells and expanded these in cell culture. The isolated cells were then identified as potential stem cells using various molecular biology techniques. "The laboratory analyses, such as immunohistochemistry, genetic analysis and flow cytometry, aimed to identify the stem cells through specific cell markers, i.e. the expression of genes and the presence of certain surface proteins," explains first author Elisabeth Rink. For comparison with the endometrial cells, stem cells obtained from the bone marrow by traditional surgical techniques were analysed in the same way.

Cells obtained from the uterus clearly expressed the same markers as bone marrow stem cells. Furthermore, the scientists were able to show in cell culture conditions that the endometrial stem cells differentiated into fat, bone, cartilage and muscle cell lines. "The endometrium provides a source of mesenchymal stem cells that can be easily accessed with little stress to the animals. The cell culture results show that these cells can be of benefit not only in the treatment of uterine conditions, but that they can also replace the need for surgically obtained stem cells for therapeutic purposes in other tissue types," concludes senior researcher Christine Aurich.