The Combination of Adipose-derived Schwann-like Cells and Acellular Nerve Allografts Promotes Sciatic Nerve Regeneration and Repair through the JAK2/STAT3 Signaling Pathway in Rats

Schwann cells (SCs) combined with acellular nerve allografts (ANAs) effectively promote the regeneration and repair of peripheral nerves, but the exact mechanism has not been fully elucidated. However, the disadvantages of SCs include their limited source and slow rate of expansion in vitro. Previous studies have found that adipose-derived stem cells have the ability to differentiate into Schwann-like cells. Therefore, we speculated that Schwann-like cells combined with ANAs could profoundly facilitate nerve regeneration and repair. The aim of the present study was to investigate the cellular and molecular mechanisms of regeneration and repair. In this study, tissue-engineered nerves were first constructed by adipose-derived Schwann-like cells and ANAs to bridge missing sciatic nerves. Then, the rats were randomly divided into five groups (n = 12 per group): a Control group; a Model group; an ADSC group; an SC-L group; and a DMEM group. Twelve weeks postsurgery, behavioral function tests and molecular biological techniques were used to evaluate the function of regenerated nerves and the relevant molecular mechanisms after sciatic nerve injury (SNI). The results showed that adipose-derived Schwann-like cells combined with ANAs markedly promoted sciatic nerve regeneration and repair. These findings also demonstrated that the expression of neurotrophic factors (NFs) was increased, and the expression of Janus activated kinase2 (JAK2)/P-JAK2, signal transducer and activator of transcription-3 (STAT3)/P-STAT3 was decreased in the spinal cord after SNI. Therefore, these results suggested that highly expressed NFs in the spinal cord could promote nerve regeneration and repair by inhibiting activation of the JAK2/STAT3 signaling pathway.

Combination of BMSCs-laden acellular nerve xenografts transplantation and G-CSF administration promotes sciatic nerve regeneration

Peripheral nerve gaps often lead to interrupted innervation, manifesting as severe sensory and motor dysfunctions. The repairs of the nerve injuries have not achieved satisfactory curative effects in clinic. The transplantation of bone marrow stromal cells (BMSCs)-laden acellular nerve xenografts (ANX) has been proven more effective than the acellular nerve allografting. Besides, granulocyte colony-stimulating factor (G-CSF) can inhibit inflammation and apoptosis, and thus is conducive to the microenvironmental improvement of axonal regeneration. This study aims to investigate the joint effect of BMSCs-seeded ANX grafting and G-CSF administration, and explore the relevant mechanisms. Adult SD rats were divided into five groups randomly: ANX group, ANX combined with G-CSF group, BMSCs-laden ANX group, BMSCs-laden ANX combined with G-CSF group, and autograft group. Eight weeks after transplantation, the detection of praxiology and neuroelectrophysiology was conducted, and then the morphology of the regenerated nerves was analyzed. The inflammatory response and apoptosis in the nerve grafts as well as the expression of the growth-promoting factors in the regenerated tissues were further assayed. G-CSF intervention and BMSCs implanting synergistically promoted peripheral nerve regeneration and functional recovery following ANX bridging, and the restoration effect was matchable with that of the autologous nerve grafting. Moreover, local inflammation was alleviated, the apoptosis of the seeded BMSCs was decreased, and the levels of the neuromodulatory factors were elevated. In conclusion, the union application of BMSCs-implanted ANX and G-CSF ameliorated the niche of neurotization and advanced nerve regeneration substantially. The strategy achieved the favorable effectiveness as an alternative to the autotransplantation.

Adsorptive properties of graphene oxide on vitamin B12 and their effect on the promotion of peripheral nerve regeneration

OBJECTIVES

To observe whether Graphene oxide (GO) can absorb vitamin B12 (VB12) and Decellularized scaffold - acellular nerve allograft (ANA) modified GO-VB12 promote the repair of ischiadic nervus defects in a rat model.

METHODS

The adsorption of GO on vitamin and the optimum adsorption conditions were investigated by single factor experiment. The adsorption properties of the material were observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) to determine the success of adsorption on VB12. GO-VB12-ANA was prepared by vibration mixing method and bridged to injured ischiadic nervus. The nerve action potential, wet weight ratio of gastrocnemius muscle and the expression of GAP-43 were investigated by contrast test to detect its effect on nerve regeneration.

RESULTS

The optimized adsorption conditions for GO on VB12 solution were listed as follows: adsorbent dosage was 6 mg, shaking time was 70 min, the pH value was 6, the optimum concentration of VB12 was 50 mg/L and the theoretical saturated adsorption capacity was 21.51 mg/g. The nerve action potential, wet weight ratio of gastrocnemius muscle and the expression of GAP-43 in nerve fiber of GO-VB12-ANA group were close to the normal values and significantly higher than those of ANA and rotation group.

CONCLUSIONS

Based on the adsorption function of GO on VB12, GO-VB12-ANA can promote regeneration of injured ischiadic nervus, providing the experimental basis for the clinical application of nanomaterials.

Synergistic effects of G-CSF and bone marrow stromal cells on nerve regeneration with acellular nerve xenografts

Peripheral nerve defects result in severe denervation presenting sensory and motor functional incapacitation. Currently, a satisfactory therapeutic treatment promoting the repair of injured nerves is not available. As shown in our previous study, acellular nerve xenografts (ANX) implanted with bone marrow stromal cells (BMSCs) replaced allografts and promoted nerve regeneration. Additionally, granulocyte-colony stimulating factor (G-CSF) has been proven to mobilize supplemental cells and enhance vascularization in the niche. Thus, the study aimed to explore whether the combination of G-CSF and BMSC-laden ANX exhibited a synergistic effect. Adult Sprague-Dawley (SD) rats were randomly divided into five groups: ANX group, ANX combined with G-CSF group, BMSCs-laden ANX group, BMSCs-laden ANX combined with G-CSF group and autograft group. Electrophysiological parameters and weight ratios of tibialis anterior muscles were detected at 8 weeks post-transplantation. The morphology of the regenerated nerves was assayed, and growth-promoting factors present in the nerve grafts following G-CSF administration or BMSCs seeding were also investigated. Nerve regeneration and functional rehabilitation induced by the combination therapy were significantly advanced, and the rehabilitation efficacy was comparable with autografting. Moreover, the expression of Schwann cell markers, neurotrophic factors and neovessel markers in the nerve grafts was substantially increased. In conclusion, G-CSF administration and BMSCs transplantation synergistically promoted the regeneration of ANX-bridged nerves, which offers a superior strategy to replace autografts in repairing peripheral nerve injuries.

Synergistic effects of ultrashort wave and bone marrow stromal cells on nerve regeneration with acellular nerve allografts

Acellular nerve allografts (ANA) possess bioactivity and neurite promoting factors in nerve tissue engineering. Previously we reported that low dose ultrashort wave (USW) radiation could enhance the rate and quality of peripheral nerve regeneration with ANA repairing sciatic nerve defects. Meanwhile, ANA implanted with bone marrow stromal cells (BMSCs) exhibited a similar result. Thus, it is interesting to know whether it might yield a synergistic effect when USW radiation is combined with BMSCs-laden ANA. Here we investigated the effectiveness of ANA seeded with BMSCs, combined with USW therapy on repairing peripheral nerve injuries. Adult male Wistar rats were randomly divided into four groups: Dulbecco's modified Eagle's medium (DMEM) control group, BMSCs-laden group, ultrashort wave (USW) group and BMSC + USW group. The regenerated nerves were assayed morphologically and functionally, and growth-promoting factors in the regenerated tissues following USW administration or BMSCs integration were also detected. The results indicated that the combination therapy caused much better beneficial effects evidenced by increased myelinated nerve fiber number, myelin sheath thickness, axon diameter, sciatic function index, nerve conduction velocity, and restoration rate of tibialis anterior wet weight. Moreover, the mRNA levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in the spinal cord and muscles were elevated significantly. In conclusion, we found a synergistic effect of USW radiation and BMSCs treatment on peripheral nerve regeneration, which may help establish novel strategies for repairing peripheral nerve defects.

Sciatic nerve repair by acellular nerve xenografts implanted with BMSCs in rats xenograft combined with BMSCs

Acellular nerves possess the structural and biochemical features similar to those of naive endoneurial tubes, and have been proved bioactive for allogeneil graft in nerve tissue engineering. However, the source of allogenic donators is restricted in clinical treatment. To explore sufficient substitutes for acellular nerve allografts (ANA), we investigated the effectiveness of acellular nerve xenografts (ANX) combined with bone marrow stromal cells (BMSCs) on repairing peripheral nerve injuries. The acellular nerves derived from Sprague-Dawley rats and New Zealand rabbits were prepared, respectively, and BMSCs were implanted into the nerve scaffolds and cultured in vitro. All the grafts were employed to bridge 1 cm rat sciatic nerve gaps. Fifty Wistar rats were randomly divided into five groups (n = 10 per group): ANA group, ANX group, BMSCs-laden ANA group, BMSCs-laden ANX group, and autologous nerve graft group. At 8 weeks post-transplantation, electrophysiological study was performed and the regenerated nerves were assayed morphologically. Besides, growth-promoting factors in the regenerated tissues following the BMSCs integration were detected. The results indicated that compared with the acellular nerve control groups, nerve regeneration and functional rehabilitation for the xenogenic nerve transplantation integrated with BMSCs were advanced significantly, and the rehabilitation efficacy was comparable with that of the autografting. The expression of neurotrophic factors in the regenerated nerves, together with that of brain-derived neurotrophic factor (BDNF) in the spinal cord and muscles were elevated largely. In conclusion, ANX implanted with BMSCs could replace allografts to promote nerve regeneration effectively, which offers a reliable approach for repairing peripheral nerve defects.

Synergistic effects of bone mesenchymal stem cells and chondroitinase ABC on nerve regeneration after acellular nerve allograft in rats

This study aimed to evaluate whether combination therapy of bone marrow stromal cells (BMSCs) transplantation and chondroitinase ABC (ChABC) treatment further enhances axonal regeneration and functional recovery after acellular nerve allograft repair of the sciatic nerve gap in rats. Eight Sprague-Dawley rats were used as nerve donors, and 32 Wistar rats were randomly divided into four groups: Group I: acellular rat sciatic nerve (ARSN) group; Group II: ChABC treatment; Group III: BMSCs transplantation; and Group IV: ChABC treatment and BMSCs transplantation. The results showed that compared with ARSN control group, BMSC transplantation promoted axonal regeneration, the secretion of neural trophic factors NGF, BDNF and axon angiogenesis in nerve graft. ChABC treatment degraded chondroitin sulfate proteoglycans in ARSN in vitro and in vivo and improved BMSCs survival in ARSN. The combination therapy caused much better beneficial effects evidenced by increasing sciatic function index, nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, and myelinated nerve number, but did not further boost the therapeutic effects on neurotrophic factor production, axon angiogenesis, and sensory functional recovery by BMSC transplantation. Taken together, for the first time, we demonstrate the synergistic effects of BMSC transplantation and BMSCs treatment on peripheral nerve regeneration, and our findings may help establish novel strategies for cell transplantation therapy for peripheral nerve injury.

Biocompatibility of acellular nerves of different mammalian species for nerve tissue engineering

To explore the biocompatibility of acellular nerves of different mammalian species, for the acellular nerves derived from rats and rabbits, the morphology, immunocompatibility, and cytocompatibility with bone marrow stromal cells (BMSCs) were evaluated. The results indicated that the tridimensional architecture and main proteins of endoneurial tubes in both biomaterials were well retained. The nerve scaffolds did not show immunogenicity or cytotoxicity, but facilitated growth of BMSCs and secretion of neurotrophic factors in vitro. In conclusion, acellular nerves of different species possess favorable biocompatibility, and xenogenic acellular nerves combined with BMSCs have potential to replace allografts for peripheral nerve reconstruction.

Adipose-derived stem cells promote peripheral nerve repair

INTRODUCTION

Recent evidence suggests that the implantation of bone marrow-derived mesenchymal stem cells improves peripheral nerve regeneration. In this study we aimed to investigate whether adipose-derived stem cells (ADSCs) can be used for peripheral nerve repair.

MATERIAL AND METHODS

In a rat model, nerve regeneration was evaluated across a 15 mm lesion in the sciatic nerve by using an acellular nerve injected with allogenic ADSCs. The walking behaviour of rats was measured by footprint analysis, and electrophysiological analysis and histological examination were performed to evaluate the efficacy of nerve regeneration.

RESULTS

Cultured ADSCs became morphologically homogeneous with a bipolar, spindle-like shape after ex vivo expansion. Implantation of ADSCs into the rat models led to (i) improved walking behaviour as measured by footprint analysis, (ii) increased conservation of muscle-mass ratio of gastrocnemius and soleus muscles, (iii) increased nerve conduction velocity, and (iv) increased number of myelinated fibres within the graft.

CONCLUSIONS

Adipose-derived stem cells could promote peripheral nerve repair in a rat model. Although the detailed mechanism by which ADSCs promote peripheral nerve regeneration is being investigated in our lab, our results suggest that ADSCs transplantation represents a powerful therapeutic approach for peripheral nerve injury.

Improving nerve regeneration of acellular nerve allografts seeded with SCs bridging the sciatic nerve defects of rat

The objective of the paper is to evaluate the effect of acellular nerve allografts (ANA) seeded with Schwann cells to promote nerve regeneration after bridging the sciatic nerve defects of rats and to discuss its acting mechanisms. Schwann cells were isolated from neonatal Wistar rats. In vitro Schwann cells were microinjected into acellular nerve allografts and co-cultured. Twenty-four Wistar rats weighing 180-220 g were randomly divided into three groups with eight rats in each group: ANA seeded with Schwann cells (ANA + SCs), ANA group and autografts group. All the grafts were, respectively, served for bridging a 10-mm long surgically created sciatic nerve gap. Examinations of regeneration nerve were performed after 12 weeks by transmission electron microscope (TEM), scanning electron microscope (SEM), and electrophysiological methods, and then analyzed statistically. The results obtained indicated that in vitro Schwann cells displayed the feature of bipolar morphology with oval nuclei. Compared with ANA group, the conduction velocity of ANA + SCs group and autograft group was faster after 12 weeks, latent period was shorter, and wave amplitude was higher (P < 0.05). The difference between ANA + SCs group and autograft group is not significant (P > 0.05). Regeneration nerve myelinated fiber number, myelin sheath thickness, and myelinated fibers/total nerves (%) in both ANA + SCs group and autograft group are higher than that in ANA group; the difference is significant (P < 0.05). The difference between the former two is not significant (P > 0.05). In conclusion, ANA seeded with SCs could improve nerve regeneration and functional recovery after bridging the sciatic nerve gap of rats, which offers a novel approach for the repair peripheral nerve defect.

[The assembly of low molecular weight neurofilament protein (NF-L) in vitro]

Neurofilaments were isolated from bovine spinal cords by ultra-speed centrifugation and examined by negative staining. The neurofilament triplet proteins: NF-L, NF-M and NF-H were purified by DE-52 anion exchange chromatography in the presence of 6 mol/L urea. The reassembly of NF-L under controlled conditions was studied. NF-L can reassemble into 10 nm width filaments within 60 minutes at physiological condition of around 0.15 mol/L NaCl, 2 mmol/L MgCl2, neutral pH(pH 6.8) and 37 degrees C. In 6 mol/L urea, NF-L was examined as 12 nm-diameter particle by low angle rotary shadowing. When dialyzed against reassembly buffer for 20 minutes, some irregular filaments were formed. Further dialyzed for another 40 minutes, the long smooth filaments appeared. Some filaments were unraveled at the end regions, where existed 2-4 subfilaments. Four subfilaments were more often observed. That is to say, the 10 nm-width filament was composed of 4 subfilaments. While dialyzed against the alkaline buffer containing 0.15 mol/L NaCl, NF-L reconstituted into 45-180 nm-long, 10 nm-width filaments, which were not able to elongate into long filaments.

Sciatic nerve regeneration navigated by laminin-fibronectin double coated biodegradable collagen grafts in rats

Biodegradable type I collagen tube grafts filled longitudinally with laminin and fibronectin double coated collagen fiber bundles (L-F grafts) were implanted to promote sciatic nerve regeneration in rats. Grafts filled with uncoated collagen fibers were used as control. A 1 cm defect on the right sciatic nerve was filled with a graft in the manner of bridging. Thirty days after implantation, several newly developed nerve fasciculi were found at the middle portion of the L-F grafts in contrast to no developed nerves in the controls. After 60 days, the middle and distal portions of both grafts included well-developed nerve tissues with prominent myelinated and unmyelinated nerve fibers surrounded by perineural cells, but the control distal portion showed fewer nerve fibers. All artificial collagen elements were completely degraded and absorbed at 30 days, and new nerve tissues surrounded by an epineurium successfully connected the proximal stump to the distal stump of the initially separated nerve. Descending and ascending action potentials were evoked in all grafts at 60 days. These results indicated that laminin and fibronectin may promote the growth of axons in biodegradable collagen grafts, which guided nerve regeneration well and allowed the formation of epineurium.

Chemical Study on the Alkaloids of Corydalis hsuchowensis

Ten alkaloids were isolated from the bulb of CORYDALIS HSUCHOWENSIS W. Y. Lian nov. ined. Among them nine alkaloids are known, identified as (-)-stylopine ( 1), cheilanthifoline ( 2), (+)-adlumidine ( 3), (+)-bicuculline ( 4), sibiricine ( 5), humosine A ( 6), (+)-bulbocapnine ( 7), (-)-scoulerine ( 8), and protopine ( 10), respectively. The other one is a new isoquinoline alkaloid. The structure was deduced as 9 based on spectroscopic analysis and chemical reactions. It was named coryximine.