Preferred Sources for Isolating Stem Cells in Dogs

Stem cell research has increased significantly in human medicine over the past 20 years, and stem cells derived from sites including bone marrow and adipose tissue are now widely used to treat various diseases. Comparatively, stem cell therapy has been explored minimally in veterinary medicine. Researchers at the Konkuk University’s Center for Stem Cell Research in South Korea recently provided a review of mesenchymal stem cell (MSC) therapy in animals.

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Mesenchymal Stem Cells

MSCs differ from hematopoietic stem cells in that they can differentiate into osteoblasts, adipocytes, cardiomyocytes, chondrocytes, hepatocytes, and stem cells. MSCs can be isolated from the following adult, neonatal, and fetal tissues:

• Bone marrow
• Adipose tissue
• Heart
• Peripheral blood
• Dermis
• Umbilical cord blood (UBC)
• Placenta
• Amniotic fluid

MSC implantation has been explored for the treatment of a variety of disorders in animals, including atopic dermatitis, osteoarthritis, chronic kidney disease, spinal cord injury, and skin wounds. According to the study authors, an important next step is to determine an ideal tissue source for high yield of MSCs.

Umbilical Cord Blood

Collection of MSCs from UCB has been explored primarily in humans, sheep, and horses. Relatively few studies have examined UCB-MSC use in pet animals, including dogs.

While collecting UCB is noninvasive and associated with low morbidity, this source yields significantly fewer MSCs compared with other tissues, such as bone marrow. Human studies showed that UCB-MSC isolation into cell culture media had a low estimated success rate of 26%, but the likelihood of successful isolation relied heavily on obtaining sufficient blood volume. Similarly, UCB-MSC yield in horses, goats, and sheep reportedly increases with increasing blood volume. While some canine studies have successfully isolated MSCs from UCB volumes as low as 8 mL, the authors of the current study reported an average yield of only 1 mL of UCB with a 66% success rate for MSC isolation. Thus, UCB may prove to be an unreliable source of stem cells in canine subjects.

Another important consideration is that UCB can only be obtained during C-section in the dog, as the bitch typically consumes the placenta and umbilical cord during natural birth. While 1 study reported higher MSC yields from fetal heart tissue, this method is more invasive and raises ethical concerns. Therefore, the authors stated that alternative options to neonatal and fetal tissues should be explored.

Adipose and Reproductive Tissues

Adipose tissue can also be used for MSC collection, as cells from this source can differentiate into adipogenic, osteogenic, and chrondrogenic types. Interestingly, reproductive tissues also yield high numbers of MSCs. Although ovaries and testes are frequently discarded as medical waste during sterilization, both tissues are “proven to be potent and reliable sources of MSCs,” according to the authors. Both also have the same multipotent potential as do adipose-derived MSCs. Therefore, the authors recommended future use of reproductive and adipose tissues, rather than UCB, for MSC collection in veterinary medicine.

Dr. Stilwell received her DVM from Auburn University, followed by a MS in fisheries and aquatic sciences and a PhD in veterinary medical sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.