Effect of MDL-28170 on Infarct Size and Graft Function in Rat Hearts Following Donation after Circulatory Death with Prolonged Warm Ischemia Time
Presented During:
Friday, September 20, 2024: 5:00PM - 6:30PM
Omni King Edward Hotel
Abstract No:
10132
Submission Type:
Abstract Submission
Authors:
Zachary Kiernan (1), Gina Labate (1), Qun Chen (1), Mohammed Quader (1)
Institutions:
(1) Virginia Commonwealth University, Richmond, VA
Submitting Author:
Zachary Kiernan
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Virginia Commonwealth University
Virginia Commonwealth University
Co-Author(s):
Gina Labate
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Virginia Commonwealth University
Virginia Commonwealth University
Qun Chen
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Virginia Commonwealth University
Virginia Commonwealth University
Mohammed Quader
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Virginia Commonwealth University
Virginia Commonwealth University
Presenting Author:
Zachary Kiernan
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Abstract:
Objective: Donation after circulatory death (DCD) is a promising strategy to alleviate the shortage of hearts for transplantation. Ischemia-reperfusion injury (IRI) is inherent to the DCD process and is proportional to warm ischemia time (WIT). Therefore, donor hearts with WIT beyond 30 minutes are generally not accepted. A principal mediator of IRI is calpain-1 (CPN1), a cysteine protease found within the cytosol and mitochondria. CPN1 activation leads to degradation of cytosol and mitochondrial structural proteins, ultimately resulting in mitochondrial dysfunction and cell death. MDL-28170 (MDL) is a selective CPN1 inhibitor and has been shown to limit cardiac IRI in DCD hearts undergoing 25 minutes of ischemia; however, data beyond this ischemia time is unknown. Our aim was to assess infarct size and graft function of DCD rat hearts treated with MDL during reperfusion following 35 minutes of ischemia.
Methods: Male Sprague-Dawley rats were assigned to one of three groups: continuous beating-heart donors (CBD) (n=10), DCD donors with 35 minutes of ischemia without MDL treatment (n=7), and DCD donors with 35 minutes of ischemia with MDL treatment (n=8). All donor rats were anesthetized, intubated, and connected to a ventilator. Animals in the DCD protocol received vecuronium bromide (1.2 mg/kg) to paralyze the diaphragm. Ventilator support was then terminated, marking the start of the ischemia time. Following 35 minutes, hearts were procured and re-perfused ex-vivo with Krebs-Henseleit (KH) buffer on a Langendorff setup for 90 minutes. Treated hearts received 10 mM of MDL in KH buffer. CBD hearts procured without ischemia and immediately re-perfused using KH buffer served as controls. Cardiac function was assessed with a balloon-tipped catheter placed in left ventricle to record developed pressure (DP) and rate pressure product (RPP). Timed coronary effluent was collected to monitor coronary perfusion. Infarct size was measured using triphenyl-tetrazolium chloride (TTC) staining.
Results: Following 35 minutes of ischemia, rat hearts treated with MDL had significantly reduced infarct size compared to untreated hearts (33.26% ± 1.54 vs. 40.16% ± 1.53, respectively; p < 0.05). Both groups had significantly higher infarct size compared to CBD hearts (7.67% ± 1.12). Additionally, while CBD hearts demonstrated significantly higher DP, RPP and coronary effluent flow rate compared to DCD hearts, there were no significant differences between treated and untreated DCD hearts for DP (36.52 ± 2.77 mmHg vs. 24.73 ± 2.83 mmHg), RPP (8174 ± 821 mmHg*BPM vs. 6245 ± 739 mmHg*BPM) or coronary effluent flow rate (18.18 ± 0.648 mL/min vs. 13.23 ± 0.814 mL/min), respectively (Figure).
Conclusion: DCD hearts sustain large infarct with 35 minutes of ischemia. MDL treatment significantly decreased the infarct size in DCD hearts compared to untreated hearts. MDL can potentially be used to limit IRI in DCD hearts with longer ischemia times.
Methods: Male Sprague-Dawley rats were assigned to one of three groups: continuous beating-heart donors (CBD) (n=10), DCD donors with 35 minutes of ischemia without MDL treatment (n=7), and DCD donors with 35 minutes of ischemia with MDL treatment (n=8). All donor rats were anesthetized, intubated, and connected to a ventilator. Animals in the DCD protocol received vecuronium bromide (1.2 mg/kg) to paralyze the diaphragm. Ventilator support was then terminated, marking the start of the ischemia time. Following 35 minutes, hearts were procured and re-perfused ex-vivo with Krebs-Henseleit (KH) buffer on a Langendorff setup for 90 minutes. Treated hearts received 10 mM of MDL in KH buffer. CBD hearts procured without ischemia and immediately re-perfused using KH buffer served as controls. Cardiac function was assessed with a balloon-tipped catheter placed in left ventricle to record developed pressure (DP) and rate pressure product (RPP). Timed coronary effluent was collected to monitor coronary perfusion. Infarct size was measured using triphenyl-tetrazolium chloride (TTC) staining.
Results: Following 35 minutes of ischemia, rat hearts treated with MDL had significantly reduced infarct size compared to untreated hearts (33.26% ± 1.54 vs. 40.16% ± 1.53, respectively; p < 0.05). Both groups had significantly higher infarct size compared to CBD hearts (7.67% ± 1.12). Additionally, while CBD hearts demonstrated significantly higher DP, RPP and coronary effluent flow rate compared to DCD hearts, there were no significant differences between treated and untreated DCD hearts for DP (36.52 ± 2.77 mmHg vs. 24.73 ± 2.83 mmHg), RPP (8174 ± 821 mmHg*BPM vs. 6245 ± 739 mmHg*BPM) or coronary effluent flow rate (18.18 ± 0.648 mL/min vs. 13.23 ± 0.814 mL/min), respectively (Figure).
Conclusion: DCD hearts sustain large infarct with 35 minutes of ischemia. MDL treatment significantly decreased the infarct size in DCD hearts compared to untreated hearts. MDL can potentially be used to limit IRI in DCD hearts with longer ischemia times.
Mechanical Support and Thoracic Transplantation Summit:
Heart Transplant
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