Chitosan-based nerve guidance conduit with microchannels and nanofibers promotes schwann cells migration and neurite growth.

Peripheral nerve injury (PNI) is the leading cause of permanent dysfunction in movement and sensation. Despite the rapid development of tissue engineering in peripheral nerve regeneration, autograft remains the gold standard for treating PNI. Synthesized nerve guidance conduits (NGCs) were reported as a potential alternative treatment that could replace autograft. However, most current NGCs are hollow tubular structured, or NGCs with macro or microstructures, but not both. These simple structures could not meet the need for neurite and Schwann cell guidance and accelerate peripheral nerve regeneration. In the current study, we combine unidirectional freezing with electrospinning to produce a unique NGC with longitudinal microchannels and parallel nanofibers. The in vitro study showed the importance of having both features in promoting Schwann cell growth, migration, and PC-12 cells neurite elongation. The novel NGCs could provide desirable physical support and guidance for peripheral nerve regeneration. From the current study, we found both the micro feature and the nano feature are helpful in terms of helping cell migrating through the NGCs, and the combination of both features will have a syngeneic effect.

Nanofibrous Nerve Conduits with Nerve Growth Factors and Bone Marrow Stromal Cells Pre-Cultured in Bioreactors for Peripheral Nerve Regeneration.

Peripheral nerve injury (PNI) was the leading cause of permanent dysfunction in movement and sensation. Synthesized nerve guide conduits (NGCs) with Schwann Cells (SCs) can help peripheral nerve regeneration. However, poor accessibility of SCs and lack of full coverage of seeded cells on NGCs can lead to failure of nerve regeneration across long gaps and full functional recovery. To overcome these limitations, bone marrow stromal cells (BMSCs) and a novel culture method were proposed in the current study. BMSCs were harvested and seeded on a never growth factor (NGF)-loaded PCL nanofibrous NGCs and cultured with a rotary cell culture system (RCCS) before implantation. The NGCs were tested in vitro with PC-12 cells to validate the bioactivity of released NGF and to access its ability to promote neurite extension. Also, the NGCs were tested in vivo with rat sciatic nerve model to exam its potential in bridging the long gap (15 mm segmental defect). The efficacy of the NGCs was investigated based on the results of the functional test, electrophysiology test, muscle atrophy, and histological analysis. The results of in vitro PC-12 cell study confirmed the bioactivity of released NGF and showed a significant increase in the neurite extension with the help of PEG-diamine and BSA. These results showed that the novel loading method could preserve the bioactivity of growth factors and achieve a sustained release in vitro. Besides, the results of the in vivo study exhibited a significant increase with the combination of all additives. These results showed that with the help of NGF and RCCS, the NGCs with the seeded BMSCs could enhance peripheral nerve regeneration across long nerve injury gaps.

Label-free fluorescent enzymatic assay of citrate synthase by CoA-Au(I) co-ordination polymer and its application in a multi-enzyme logic gate cascade.

Citrate synthase (CS) is one of the key metabolic enzymes in the Krebs tricarboxylic acid (TCA) cycle. It regulates energy generation in mitochondrial respiration by catalysing the reaction between oxaloacetic acid (OAA) and acetyl coenzyme A (Ac-CoA) to generate citrate and coenzyme A (CoA). CS has been shown to be a biomarker of neurological diseases and various kinds of cancers. Here, a label-free fluorescent assay has been developed for homogeneously detecting CS and its inhibitor based on the in situ generation of CoA-Au(I) co-ordination polymer (CP) and the fluorescence signal-on by SYBR Green II-stained CoA-Au(I) CP. Because of the unique property of the CoA-Au(I) CP, this CS activity assay method could achieve excellent selectivity and sensitivity, with a linear range from 0.0033 U/µL to 0.264 U/µL and a limit of detection to be 0.00165 U/µL. Meanwhile, this assay method has advantages of being facile and cost effective with quick detection. Moreover, based on this method, a biomimetic logic system was established by rationally exploiting the cascade enzymatic interactions in TCA cycle for chemical information processing. In the TCA cycle-derived logic system, an AND-AND-AND-cascaded gate was rigorously operated step by step in one pot, and is outputted by a label-free fluorescent signal with visualized readout.