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Zhou L, Alatrach M, Zhao T, Oliphint P, Bittner GD. Survival of rat sciatic nerve segments preserved in storage solutions ex vivo assessed by novel electrophysiological and morphological criteria. Neural Regen Res 2023; 18:2082-2088. [PMID: 36926735 DOI: 10.4103/1673-5374.367848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Most organ or tissue allografts with viable cells are stored in solutions ex vivo for hours to several days. Most allografts then require rapid host revascularization upon transplantation to maintain donor-cell functions (e.g., cardiac muscle contractions, hepatic secretions). In contrast, peripheral nerve allografts stored ex vivo do not require revascularization to act as scaffolds to guide outgrowth by host axons at 1-2 mm/d, likely aided by viable donor Schwann cells. Using current storage solutions and protocols, axons in all these donor organ/tissue/nerve transplants are expected to rapidly become non-viable due to Wallerian degeneration within days. Therefore, ex vivo storage solutions have not been assessed for preserving normal axonal functions, i.e., conducting action potentials or maintaining myelin sheaths. We hypothesized that most or all organ storage solutions would maintain axonal viability. We examined several common organ/tissue storage solutions (University of Wisconsin Cold Storage Solution, Normosol-R, Normal Saline, and Lactated Ringers) for axonal viability in rat sciatic nerves ex vivo as assessed by maintaining: (1) conduction of artificially-induced compound action potentials; and (2) axonal and myelin morphology in a novel assay method. The ten different storage solution conditions for peripheral nerves with viable axons (PNVAs) differed in their solution composition, osmolarity (250-318 mOsm), temperature (4°C vs. 25°C), and presence of calcium. Compound action potentials and axonal morphology in PNVAs were best maintained for up to 9 days ex vivo in calcium-free hypotonic diluted (250 mOsm) Normosol-R (dNR) at 4°C. Surprisingly, compound action potentials were maintained for only 1-2 days in UW and NS at 4°C, a much shorter duration than PNVAs maintained in 4°C dNR (9 days) or even in 25°C dNR (5 days). Viable axons in peripheral nerve allografts are critical for successful polyethylene glycol (PEG)-fusion of viable proximal and distal ends of host axons with viable donor axons to repair segmental-loss peripheral nerve injuries. PEG-fusion repair using PNVAs prevents Wallerian degeneration of many axons within and distal to the graft and results in excellent recovery of sensory/motor functions and voluntary behaviors within weeks. Such PEG-fused PNVAs, unlike all other types of conventional donor transplants, are immune-tolerated without tissue matching or immune suppression. Preserving axonal viability in stored PNVAs would enable the establishment of PNVA tissue banks to address the current shortage of transplantable nerve grafts and the use of stored PEG-fused PNVAs to repair segmental-loss peripheral nerve injuries. Furthermore, PNVA storage solutions may enable the optimization of ex vivo storage solutions to maintain axons in other types of organ/tissue transplants.
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Affiliation(s)
- Liwen Zhou
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Monzer Alatrach
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Ted Zhao
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Paul Oliphint
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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Luongo TS, Eller JM, Lu MJ, Niere M, Raith F, Perry C, Bornstein MR, Oliphint P, Wang L, McReynolds MR, Migaud ME, Rabinowitz JD, Johnson FB, Johnsson K, Ziegler M, Cambronne XA, Baur JA. SLC25A51 is a mammalian mitochondrial NAD + transporter. Nature 2020; 588:174-179. [PMID: 32906142 PMCID: PMC7718333 DOI: 10.1038/s41586-020-2741-7] [Citation(s) in RCA: 140] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 09/01/2020] [Indexed: 12/11/2022]
Abstract
Mitochondria require nicotinamide adenine dinucleotide (NAD+) in order to carry out the fundamental processes that fuel respiration and mediate cellular energy transduction. Mitochondrial NAD+ transporters have been identified in yeast and plants 1,2 but their very existence is controversial in mammals 3–5. Here we demonstrate that mammalian mitochondria are capable of taking up intact NAD+ and identify SLC25A51 (an essential 6,7 mitochondrial protein of previously unknown function, also known as MCART1) as a mammalian mitochondrial NAD+ transporter. Loss of SLC25A51 decreases mitochondrial but not whole-cell NAD+ content, impairs mitochondrial respiration, and blocks the uptake of NAD+ into isolated mitochondria. Conversely, overexpression of SLC25A51 or a nearly identical paralog, SLC25A52, increases mitochondrial NAD+ levels and restores NAD+ uptake into yeast mitochondria lacking endogenous NAD+ transporters. Together, these findings identify SLC25A51 as the first transporter capable of importing NAD+ into mammalian mitochondria.
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Affiliation(s)
- Timothy S Luongo
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jared M Eller
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Mu-Jie Lu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Marc Niere
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Fabio Raith
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.,Faculty of Chemistry and Earth Sciences, University of Heidelberg, Heidelberg, Germany
| | - Caroline Perry
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc R Bornstein
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Paul Oliphint
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Lin Wang
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Melanie R McReynolds
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Marie E Migaud
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - F Brad Johnson
- Department of Pathology and Laboratory Medicine, Perlman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kai Johnsson
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.,Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Mathias Ziegler
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Xiaolu A Cambronne
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA.
| | - Joseph A Baur
- Department of Physiology and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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