Derp the Jack Russell is one lucky dog. His owner practically grew up in her dad’s veterinary clinic and became a veterinary technician, so she knew what to do when Derp was lethargic and vomiting after he’d been just fine the day before. Following a trip to the veterinarian, Derp was diagnosed with immune-mediated hemolytic anemia (IMHA).
He was immediately given a blood transfusion and put on immunosuppressants. For the next few weeks, Derp and his owners found themselves riding an emotional and physical roller coaster so common with this disease. Low PCV values are often followed by blood transfusions, which temporarily raise these values that may once again plummet and be followed by more transfusions. After his sixth transfusion, Derp’s owners decided to try plasmapheresis. Unfortunately, Derp developed transfusion related acute lung injury (TRALI) and was subsequently placed in an oxygen cage.
Prognosis was bleak and Derp’s owners knew they had to find something else to keep him alive. Searching online to find anyone who had information on treating this deadly disease, they discovered stem cell therapy was an option.
After a thorough case evaluation and consultation, followed by an overnight shipment, Derp was able to get stem cells intravenously right there in his local veterinary hospital. After the stem cells, no more transfusions were needed. Derp’s lungs cleared up, and his PCV continued to rise to normal levels.
I have been a veterinarian in the Houston area for a few decades and began utilizing stem cell therapy in my clinical cases over the past five years that go beyond the traditional applications for arthritis and joint issues. After getting past my initial skepticism of stem cells and realizing there was real science behind them, I became intrigued.
Intrigued enough that five years later Safari Veterinary Care Centers has one of the fully equipped, state-of-the-art stem cell labs outside the university system that enables us to treat cases that reach beyond run-of-the-mill arthritis. The Safari lab is the result of a thirst for knowledge and quest to more effectively treat disease along with a healthy financial investment. How do you culture and grow enough cells for therapy? How many stem cells given intravenously are effective? How do you count the cells, let alone know if the cells are still alive? These and many more questions drove me to study existing research and obtain the knowledge to treat more complex conditions and diseases, including IMHA.
Many veterinarians could be intimidated by a case of fulminating IMHA, and many refer these cases to specialists. IMHA and immune thrombocytopenia (ITP) are challenging diseases without cut-and-dried treatment protocols.
Blood transfusions can buy the pet time until immunosuppressants take effect, but neither transfusions nor drugs treat the underlying cause of the immune reaction that results in the anemia. Stem cells do, however, treat the underlying cause and are showing real promise in the clinical setting. How so?
Mesenchymal stem cells (MSCs) exert powerful immunomodulatory effects by both cell-to-cell contact and by secreting powerful chemicals.1 When administered intravenously, the cells begin working immediately. IMHA targets the red blood cells, and this reaction occurs within the blood vessels or in the spleen and is designated as intravascular or extravascular IMHA respectively.
When the reaction is intravascular, literally billions of red blood cells are tagged by antibodies each second. Tagged red blood cells are killed by the activation of Complement. Complement is called this because it complements the immune system. Complement creates holes in the red blood cells allowing fluid to leak in which causes them to burst. How can stem cells help? The action of Complement is blocked by Factor H. Stem cells produce Factor H constitutively; that is, they make Factor H regardless of need.2,3,4 Intravenous stem cells can quickly stop the tagged red blood cells from being destroyed. But that’s not all stem cells do. Stem cells also direct the formation of Regulatory T-Cells (tReg cells).4 Regulatory T-cells are a specialized group of white blood cells. Their job is to create immune tolerance of the red blood cells. These T-cells limit the production of anti-red blood cell antibodies by tolerating the presence of the body’s red blood cells (see “Immune tolerance.”)
With extravascular IMHA, “nibbles” are bitten off the surface of the red blood cells by macrophages as the red blood cells pass through the spleen and liver. This process of phagocytosis removes whole red blood cells from circulation while creating spherocytes from the partially nibbled cells. Stem cells downregulate this phagocytosis of macrophages.4
These actions of stem cells effectively stop the red blood cell destruction in IMHA within the first 24 hours. Therefore, to more effectively treat the disease and save more lives, stem cell therapy would be best used early in the pet’s treatment plan while waiting for medications to take effect and especially in severe cases that are not responding to blood transfusions. Not only do stem cells treat IMHA, they also prevent it from returning by creating lasting immune tolerance. Memory T-cells act to remind the immune system to tolerate the red blood cells and not to attack them again in the future.4
Stem cells are poised to revolutionize both veterinary and human medicine and dogs like Derp are proof that stem cell therapy is a useful weapon in the fight against IMHA.
The challenge for veterinarians is getting access to stem cells in emergency situations. While processing adipose tissue and using the stromal vascular fraction cells works for inflammatory disease, immune-mediated diseases need pure stem cell cultures. But dogs like Derp cannot wait weeks for their cells to be cultured; they need donor cells immediately. Will veterinary hospitals of the future have their own stem cell labs, or will daily stem cell deliveries be available along with the antibiotics and painkillers of today?
|What is immune tolerance? Normal tissues all are labelled with the major histocompatibility complex. Any tissue without the major histocompatibility complex is attacked. However, the body can tolerate foreign tissue in special circumstances. A fetus is tolerated by the mother. The gut tolerates the presence of billions of bacteria. Red blood cells have jettisoned the major histocompatibility complex along with the nucleus, but they are not normally attacked.
Why? Immune tolerance. The immune system has a special group of white blood cells called regulatory T-lymphocytes whose function is to protect these groups of cells that would normally be attacked. The biochemical factors produced by the regulatory T-lymphocytes (tTreg cells) prevent red blood cells from being attacked. As the red cells age, they naturally lose the protective barrier and are removed from the circulation. If we don’t have enough tTreg cells protecting the red blood cells, then we will lose red blood cells faster than we can produce them, as in IMHA. One function of stem cells is to induce the production of new tTreg cells. This offers hope of a cure rather than lifelong immunosuppressive treatment.
Steven Garner, DVM, ABVP, owns and operates what has been termed “the most productive veterinary hospital in the world” at Safari Veterinary Care Centers near Houston, Tex. He founded Safari in 1984 with a vision to develop a model for veterinary practice in which a private practice veterinarian could practice the level of medicine taught in veterinary school. Today, Dr. Garner is among the leaders in the veterinary industry, practicing advanced regenerative medicine after embarking on a quest in 2015 to learn all he could about stem cell therapy.
- Kyurkchiev, Dobroslav, Bochev, Ivan, et al. Secretion of immunoregulatory cytokines by mesenchymal stem cells. World Journal of Stem Cells. 2014; Nov 26; 6(5):552–570.
- Mesenchymal Stem Cells Inhibit Complement Activation by secreting Factor H. Tu, Zhidan; Li, Qing Li; et al. Stem Cells and Development. 2010; Nov 19(11):1803–1809.
- The Complement Inhibitor Factor H Generates an Anti-Inflammatory and Tolerogenic State in Monocyte-Derived Dendritic Cells. Olivar, Rut; Luque, Ana, et al. The Journal of Immunology. 2016; May 15;196(10):4274-90.
- Conversion of Peripheral CD4+CD25- Naive T Cells to CD4+CD25+ Regulatory Tcells by TGF-B Induction of Transcription Factor Foxp3. Chen, WanJun; Jin, Wenwen Jin, et al. The Journal of Experimental Medicine. 2003; Dec 15;198