Hypothermic ex situ perfusion (HESP) systems are used to prolong allograft survival in solid organ transplantations and have been shown to be superior to static cold storage (SCS) methods. However, the effect of this preservation method on limb allograft survival and long-term function has not yet been tested. In this study, we investigated the long-term effects of the HESP on skeletal muscle metabolism, structure, and force generation and compared it with the current standard of preservation.
Forty male Lewis rats (250 ± 25 g) were divided into 5 groups, including naive control, sciatic nerve transection or repair, immediate transplantation, SCS, and HESP. For the SCS group, limbs were preserved at 4°C for 6 hours. In the HESP group, limbs were continuously perfused with oxygenated histidine-tryptophan-ketoglutarate (HTK) solution at 10–15°C for 6 hours. Hemodynamic and biochemical parameters of perfusion were recorded throughout the experiment. At 12 weeks, electromyography and muscle force measurements (maximum twitch and tetanic forces) were obtained along with muscle samples for histology and metabolomics analysis.
Histology demonstrated 48% myocyte injury in the HESP group compared with 49% in immediate transplantation (P = 0.96) and 74% in the SCS groups (P < 0.05). The maximum twitch force measurement revealed a significantly higher force in the HESP group compared with the SCS group (P = 0.029). Essential amino acid levels of the gastrocnemius muscle did not reach significance, with the exception of higher proline levels in the HESP group.
HESP using HTK protects viability of the limb but fails to restore muscle force in the long term.
1 Department of Orthopaedic Surgery, University of Michigan Health System, Ann Arbor, MI.
2 Department of Surgery, University of Michigan Health System, Ann Arbor, MI.
3 Department of Surgery, Division of Plastic Surgery, University of Michigan Health System, Ann Arbor, MI.
4 Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, MI.
Received 28 January 2019. Revision received 7 May 2019.
Accepted 9 May 2019.
This work was partially supported by the American Foundation for Surgery of Hand (Award Number 1429) and Michigan Regional Comprehensive Metabolomics Resource Core Grant U24 DK097153.
The authors declare no conflicts of interest.
E.G.(1) and K.O. participated in study design. E.G.(1), C.K., E.G.(2), M.P., and M.H. performed the acquisition of data. E.G.(1), C.K., E.G.(2), and M.H. performed the analysis and interpretation. E.G.(1) drafted the article. E.G.(1), A.R.-P., S.K., R.B., and K.O. performed the revision of the article.
Correspondence: Kagan Ozer, MD, Surgical Director for Hand Transplantation Program, Hand and Upper Extremity, Department of Orthopedic Surgery, University of Michigan Hospitals, 2098 S Main St, Ann Arbor, MI 48103. (email@example.com).