Scintigraphic Tracking of 99mTechnetium Labelled Equine Peripheral Blood-Derived Mesenchymal Stem Cells After Intravenous, Intramuscular and Subcutaneous Injection in Healthy Dogs.

Abstract

Background: Mesenchymal stem cell treatments in dogs have been investigated as a potential innovative alternative to current conventional therapies for a variety of conditions. So far, the precise mode of action of the MSCs has yet to be determined. The aim of this study was to gain more insights in the pharmacokinetics of MSCs by evaluating their biodistribution in healthy dogs after different injection routes.Methods: Three different studies were performed in healthy dogs to evaluate the biodistribution of radiolabelled equine peripheral blood-derived mesenchymal stem cells following intravenous, intramuscular and subcutaneous administration in comparison with free 99mTechnetium. The labelling of the equine peripheral blood-derived mesenchymal stem cells was performed using stannous chloride as reducing agent. Whole body scans were obtained using a gamma camera during a 24h follow-up.Results: The labelling efficiency ranged between 59.58 and 83.82%. Free 99mTechnetium accumulation was predominantly observed in stomach, thyroid, bladder and salivary glands while, following intravenous injection, the 99mTechnetium labelled equine peripheral blood-derived mesenchymal stem cells majorly accumulated in the liver throughout the follow-up period. After intramuscular and subcutaneous injection, the injected dose percentage remained very high at the injection site.Conclusions: A distinct difference was noted in biodistribution of the radiolabelled equine peripheral blood-derived mesenchymal stem cells compared to free 99mTechnetium indicating equine peripheral blood-derived mesenchymal stem cells have a specific pharmacokinetic pattern after systemic administration in healthy dogs. Furthermore, the natural biodistribution pattern of the used equine peripheral blood-derived mesenchymal stem cells appeared to be different to previously reported experiments using different sources of mesenchymal stem cells.

Canine adipose tissue-derived mesenchymal stem cell therapy in a dog with renal Fanconi syndrome

“…In addition, it is known that there are various methods of injecting stem cells, but in this patient, the stem cells were injected intravenously to evaluate the therapeutic effect. Evaluating the effectiveness of the treatment with other injection methods, such as the direct injection into the organ with ultrasound guidance, would be beneficial for future studies (Beerts et al 2021). In this case, only stem cells were injected alone without any other drug, but in order to increase the efficiency of the stem cell therapy, it would be good to consider applying such a vehicle to patients receiving stem cells.…”