Ultrasound-guided injection of the cranial tibial artery for stem cell administration in horses.

The research examined the feasibility of injecting stem cells into the cranial tibial artery of horses for treating injuries in the equine distal hindlimb. The researchers found this method to be safely executable using ultrasound guidance and confirmed stem cell dispersion within 24 hours post-injection, although with decreasing persistence.

Research Objectives and Methods

• The objective of the research was to evaluate the feasibility of injecting mesenchymal stem cells (MSC) into the cranial tibial artery in horses, and assess the distribution and persistence of these injected cells.
• In order to accomplish this, the research was split into three phases.
• The first phase involved catheterising the cranial tibial arteries of both hindlimbs in three research horses under general anaesthesia with ultrasound guidance. An iodinated contrast was injected into this section to highlight vascular structures on imaging studies.
• In the second phase, the team used the same method to inject iodinated contrast into three other sedated horses, but these ones were standing.
• The third phase involved injecting Technetium-HMPAO labelled allogenic bone marrow-derived equine MSC into three additional horses, again while standing and under sedation.
• Scintigraphy, a diagnostic technique using radionuclides to create two-dimensional images, was utilized to track the spread and persistence of MSCs in the body for a period of 24 hours after injection.
• Ultrasound was performed after 24 hours to check for any impairment of the vessel.

Results and Conclusion

• They successfully achieved arterial injection in all 18 limbs (3 phases * 2 limbs per horse * 3 horses per phase) without notable complications. A slight partial periarterial injection was noticed in four limbs, but this was not considered significant.
• The team found that scintigraphy demonstrated the scattered dispersion of MSC from the tarsal area to the foot.
• While the persistence of MSC decreased over time, scintigraphy still detected their presence after 24 hours.
• Limited retention of the radiolabel within the MSC was noted, possibly explaining the decrease in MSC detection over time.
• The research concluded that the ultrasound-guided cranial tibial artery injection is feasible for both anaesthetized and standing sedated horses. This method could potentially be utilized for MSC treatment of equine proximal suspensory desmopathy or other injuries in the horse’s distal hindlimb.