Survival of rat sciatic nerve segments preserved in storage solutions ex vivo assessed by novel electrophysiological and morphological criteria

Most organ or tissue allografts with viable cells are sto red in solutions ex vivo for hours to seve ral days.Most allografts then require rapid host revascula rization upon transplantation to maintain donor-cell functions(e.g.,cardiac muscle contra ctions,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 orga n/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 La ctated Ringe rs) 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 diffe rent storage solution conditions for peripheral nerves with viable axons(PNVAs) diffe red in their solution composition,osmolarity(250-318 mOsm),temperature(4℃ vs.25℃),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℃.Surprisingly,compound action potentials were maintained for only 1-2 days in UW and NS at 4℃,a much shorter duration than PNVAs maintained in 4℃ dNR(9 days) or even in 25℃ 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 sto red 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 segmentalloss 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.

The Effect of Storage Solutions on Mineral Content of Enamel

Purpose: This study evaluated the influence of different storage times and storage solutions on the mineral content of enamel. Methods: Ninety enamel slabs were randomly divided into 2 groups of 45: a 45-day group and a 90-day group. Each of these main groups was further subdivided into 9 experimental groups of 5 slabs, and each subgroup was stored in a different storage solution. The mean percentage weights of 5 elements (calcium, potassium, sodium, phosphorus, and magnesium) presented in each enamel slab was measured after storage using inductively coupled plasmaatomic emission spectrometry. Two-way analysis of variance (ANOVA) and Turkey’s honestly significant difference tests were used to analyze differences between the groups. Results: Storage conditions significantly affected the levels of calcium, potassium, sodium, and phosphorus (p 0.05). Storage procedures can significantly affect the calcium, potassium, sodium, and phosphorus contents of enamel.