Clinical use of donation after circulatory death pancreas for islet transplantation

Abstract

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.

Keywords: basic (laboratory) research/science; clinical research/practice; diabetes: type 1; donors and donation: donation after circulatory death (DCD); islet isolation; islet transplantation; islets of Langerhans; organ acceptance; regenerative medicine.

FIGURE 1

Definitions regarding periods of ischemia in organ procurement and transportation until the start of islet isolation for DCD pancreas procedures. Critical hemodynamic moments are indicated at the top part of the figure: life support “switch off,” the moment when organ perfusion is inadequate (mean arterial pressure [MAP] drops below 50 and/or O₂ saturation drops below 80%), cardiac asystole (and thereafter a “no‐touch” period), the start of cold preservation fluid perfusion, pancreatectomy, and the start of enzyme perfusion. Several ischemic periods can be defined between these time points. The total warm ischemia (tWIT) time starts at the switch off of life support and ends when cold preservation solution is perfused. The agonal phase measures the length of time between ceasing circulatory support and cardiac asystole. Functional warm ischemia time (fWIT) indicates the time that organs experience warm, inadequate oxygenation, and perfusion (time between the MAP dropping below 50 mm Hg and/or the O₂ saturation dropping below 80% until the start of cold preservation fluid perfusion). The lukewarm ischemia time (LIT) is defined as the time between the infusion of cold preservation fluid perfusion and pancreatectomy. The cold ischemia time (CIT) is the time from pancreatectomy until the infusion of digestive enzymes in the pancreas in the islet isolation facility. During the tWIT, a normothermic temperature persists. The temperature decreases during LIT when ice is packed into the abdominal cavity resulting in a gradual decrease in cell metabolism. In the CIT period, the temperature of the pancreas slowly plateaus. At the start of the agonal phase, the pancreas receives sufficient oxygenation. When perfusion becomes inadequate, at the start of the fWIT, the availability of oxygen to the pancreas decreases. Around the start of the asystolic phase, there is anoxemia. The combination of a suboptimal temperature and insufficient oxygenation results in an increasing risk of tissue damage. Actual damage is an outcome of ischemic periods combined with the risk of tissue damage

FIGURE 2

IEQ of DBD and DCD isolations immediately after isolation (day 0), at 1 day (MC1) and at 2–3 days (MC2) after isolation. At day 0, DCD islet yield was 395 515 IEQ (239 287) and DBD islet yield was 480 017 IEQ (273 449; p < .01). The decrease in IEQ after successive medium changes (MC1 and MC2) was similar in DCD and DBD pancreas. DCD n = 126. DBD n = 258

FIGURE 3

Association of ischemia periods with islet yield. (A–D) show the relation between ischemic time periods and islet yield. E‐G show the relation between islet yield and agonal phase (E), functional WIT (F), and total WIT (G). No associations are significant [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 4

Dynamic glucose‐stimulated insulin secretion test. (A) After 1 day of culture, islets were perifused with a low glucose (1.7 mmol/L) solution, a high glucose (20 mmol/L) solution, and finally the low glucose solution. The average of the last three low glucose values was defined as the baseline value. The insulin concentration at each time point was then divided by the baseline to give the stimulation index at each time point. A similar response is present in both DCD and DBD islets. Peak stimulation index values of DCD islets (5.4 ± 2.7, n = 27) and DBD islets (4.6 ± 2.9, n = 102) are not significantly different (p = .30). (B) The stimulation index curves were integrated over time to calculate the area under the curve of the stimulation index for DCD and DBD islets. No significant difference between DCD islets (295.0 ± 49.7, n = 27) and DBD islets (270.7 ± 19.0, n = 102) islets was observed, p = .64

FIGURE 5

Graft function 3 months after islet transplantation. Mixed meal tests were performed in single or double DCD graft recipients (DCD, n = 9) and in single or double DBD graft recipients (DBD, n = 31). C‐peptide (pmol/L) and glucose (mmol/L) were corrected for the number of islets per kg recipient. (A) C‐peptide concentrations during the mixed meal test. The increase in C‐peptide was similar in DBD and DCD graft recipients. (B) The area under the C‐peptide curve was not different between DCD and DBD graft recipients (DCD 0.013 ± 0.0057, DBD 0.011 ± 0.0072, p = .41). (C) Glucose concentrations during the mixed meal test. The increase in glucose was similar in DBD and DCD graft recipients. (D) The area under the glucose curve was not different between DCD and DBD graft recipients (DCD 20.0 ± 9.0, DBD 19.8 ± 8.9, p = .94)

FIGURE 6

Igls scores were assessed at 1 year (A,C) and 2 years (B,D) after the islet transplantation. (A) After 1 year, 89% of DCD islet graft recipients and 74% of DBD islet graft recipients have Igls score 1 or 2 indicating treatment success (p = .65). At 2 years after the last transplantation, this was 75% and 74% in DCD and DBD islet graft recipients, respectively (p > .99). DCD n = 9, DBD n = 31 at 1 year. DCD n = 8, DBD n = 30 at 2 years