Machine perfusion (MP) has evolved as a promising approach for the ex situ preservation in organ transplantation. However, the literature on the use of MP in human vascularized composite allografts (VCA) is scarce. The aim of this study was to evaluate the effects of hypothermic MP with an acellular perfusate in human upper extremities and compare with the current gold standard of static cold storage (SCS).
Six upper extremities were assigned to either MP (n=3) or SCS (n=3) conditions for 24 hours. MP-extremities were perfused with oxygenated Steen™ solution at a constant pressure of 30mmHg and 10°Celsius.
Median total ischemia time was 213 minutes (range, 127 to 222 minutes). Myoglobin, creatine-kinase (CK) showed increased levels at the start of MP (medians: myoglobin: 4377ng/ml, CK: 1442U/L), peaking 6 hours after perfusate exchange (medians: myoglobin: 9206ng/ml, CK: 3995U/L) at timepoint 24. Lactate levels decreased from a median of 6.9mmol/L to 2.8mmol/L over time. Expression of HIF-1α peaked in the SCS-group after 8h, followed by a decrease. Increased HIF-1α expression in the MP-group was delayed until 20h. Perfusion pressure, temperature and circuit flow were maintained at median of 30.88mmHg, 9.77°Celsius, and 31.13ml/min, respectively. Weight increased 1.4% in the SCS- and 4.3% in the MP-group over 24h.
Hypothermic ex situ perfusion with an oxygenated acellular Steen™ solution may extend the allowable extracorporeal preservation time by a factor of 4-6 compared to static cold storage and holds promise to be beneficial for VCA recipients and victims of traumatic major limb amputation.