Effects of long-term extracorporeal blood perfusion of the distal portion of isolated equine forelimbs on metabolic variables and morphology of laminar tissue.

This study sought to develop a model of long-term extracorporeal (outside the body) blood perfusion of isolated horse forelimbs that reproduces physiological conditions in the laminar tissue of hooves. The research demonstrated that for up to 10 hours, these isolated limbs can undergo perfusion without any significant tissue damage occurring.

Methods and Procedure

• For the study, the researchers sourced 18 forelimbs from 9 healthy adult horses from a licensed abattoir.
• These isolated forelimbs underwent blood perfusion for periods of 6, 8, and 10 hours under conditions that represented their physiological state.
• The blood used in the perfusion process was autologous — meaning it was taken from the same horse the limb derived from.
• To monitor cell viability and health in the perfused tissues, the research team assessed various metabolic indicators. These included factors such as lactate generation and glucose and oxygen consumption.
• Indicators of cell damage – potassium concentration and lactate dehydrogenase activity – were also examined at one-hour intervals from samples of the perfusate (fluid passing through the tissue).
• The team tracked weight gain in the forelimb to establish the edema index. This is a measure that can help to assess the occurrence of swelling in tissues due to fluid build-up.
• Upon conclusion of the perfusion procedure, the team performed light and electron microscopic examinations of the laminar tissue to evaluate it for signs of damage.

Findings and Implications

• The study found that during the hemoperfusion process, the glucose consumption, lactate generation, and oxygen consumption rates were within expected parameters.
• Moreover, the researchers did not observe significant cellular damage in the tissues. This was denoted by the absence of potassium efflux into the perfusate and a lack of notable increase in lactate dehydrogenase activity.
• Weight gain was minimal at just over 1%, indicating low levels of edema or fluid build-up which is an key sign of tissue damage.
• Follow-up microscopic examinations of the perfused laminar tissue revealed no overt signs of tissue damage.
• The findings thus demonstrate that isolated equine limbs can be successfully perfused under physiological conditions for up to 10 hours without causing structural damage to the laminar tissue.
• This suggests potential applications for such ex vivo models in the study and understanding of equine hoof health and disease.