In vivo imaging of the neuronal response to spinal cord injury:a narrative review

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury(SCI).However,this subject has been neglected in part because appropriate tools are lacking.Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease.This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques,and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI.We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations.Finally,we identify the challenges and possible solutions for spinal cord neuron imaging.

Roles of neural stem cells in the repair of peripheral nerve injury

Currently, researchers are using neural stem cell transplantation to promote regeneration after peripheral nerve injury, as neural stem cells play an important role in peripheral nerve injury repair. This article reviews recent research progress of the role of neural stem cells in the repair of peripheral nerve injury. Neural stem cells can not only differentiate into neurons, astrocytes and oligodendrocytes, but can also differentiate into Schwann-like cells, which promote neurite outgrowth around the injury. Transplanted neural stem cells can differentiate into motor neurons that innervate muscles and promote the recovery of neurological function. To promote the repair of peripheral nerve injury, neural stem cells secrete various neurotrophic factors, including brain-derived neurotrophic factor, fibroblast growth factor, nerve growth factor, insulin-like growth factor and hepatocyte growth factor. In addition, neural stem cells also promote regeneration of the axonal myelin sheath, angiogenesis, and immune regulation. It can be concluded that neural stem cells promote the repair of peripheral nerve injury through a variety of ways.

An expert consensus on the evaluation and treatment of acute thoracolumbar spine and spinal cord injury in China

This is an expert consensus on the evaluation and treatment of thoracolumbar spinal injury, estab- lished from February 2009 to July 2010. The expert consensus consists mainly of six parts with a total of 54 recommendations including the overview （one item）; pre-hospital care （one item）; evaluation and diagnosis （13 items）; treatment （23 items）; prevention and treatment of major com- plications （12 items）; and rehabilitation （four items）. This is the first time that Chinese experts have published a consensus on spine and spinal cord injury. The expert consensus was established based on Delphi methods, literature analysis, and clinical experiences. Each recommendation is supported by and was interpreted using multi-level evidences. The level of agreement with the rec- ommendation among the panel members was assessed as either low, moderate, or strong. Each panel member was asked to indicate his or her level of agreement on a 5-point scale, with ＂1＂ cor- respondJng to neutrality and ＂5＂ representJng maxJmum agreement. Scores were aggregated across the panel members and an arithmetic mean was calculated. This mean score was then translated into low, moderate, or strong. After all of the votes were collected and calculated, the results showed no low-level recommendations, 10 moderate-level recommendations, and 44 strong-level recom- mendations. An expert consensus was reached and was recognized by Chinese spine surgeons. Wide-scale adoption of these recommendations is urgent in the management of acute thora- columbar spine and spinal cord injury in a broader attempt to create a standard evaluation and treatment strategy for acute thoracolumbar spine and spinal cord injury in China.

The effects of claudin 14 during early Wallerian degeneration after sciatic nerve injury

Claudin 14 has been shown to promote nerve repair and regeneration in the early stages of Wallerian degeneration （0-4 days） in rats with sciatic nerve injury, but the mechanism underlying this process remains poorly understood. This study reported the effects of claudin 14 on nerve degeneration and regeneration during early Wallerian degeneration. Claudin 14 expression was up-regulated in sciatic nerve 4 days after Wallerian degeneration. The altered expression of claudin 14 in Schwann cells resulted in expression changes of cytokines in vitro. Expression of claudin 14 affected c-Jun, but not Akt anal ERK1/2 patl^ways, l^urther studies reve^ed that enhanced expression of claudin 14 could promote Schwann cell proliferation and migration. Silencing of claudin 14 expression resulted in Schwann cell apoptosis and reduction in Schwann cell proliferation. Our data revealed the role of claudin 14 in early Wallerian degeneration, which may provide new insights into the molecular mechanisms of Wallerian degeneration.

Differential gene expression in proximal and distal nerve segments of rats with sciatic nerve injury during Wallerian degeneration

Wallerian degeneration is a subject of major interest in neuroscience. A large number of genes are differentially regulated during the distinct stages of Wallerian degeneration： transcription factor activation, immune response, myelin cell differentiation and dedifferentiation. Although gene expression responses in the distal segment of the sciatic nerve after peripheral nerve injury are known, differences in gene expression between the proximal and distal segments remain unclear. In the present study in rats, we used microarrays to analyze changes in gene expression, biological processes and signaling pathways in the proximal and distal segments of sciatic nerves under- going Wallerian degeneration. More than 6,000 genes were differentially expressed and 20 types of expression tendencies were identified, mainly between proximal and distal segments at 7-14 days after injury. The differentially expressed genes were those involved in cell differentiation, cytokinesis, neuron differentiation, nerve development and axon regeneration. Furthermore, 11 biological processes were represented, related to responses to stimuli, cell apoptosis, inflammato- ry response, immune response, signal transduction, protein kinase activity, and cell proliferation. Using real-time quantitative PCR, western blot analysis and immunohistochemistry, microarray data were verified for four genes： aquaporin-4, interleukin 1 receptor-like 1, matrix metallopro- teinase-12 and periaxin. Our study identifies differential gene expression in the proximal and distal segments of a nerve during Wallerian degeneration, analyzes dynamic biological changes of these genes, and provides a useful platform for the detailed study of nerve injury and repair during Wallerian degeneration.

Gene expression profiling of the rat sciatic nerve in early Wallerian degeneration after injury

Wallerian degeneration is an important area of research in modern neuroscience. A large number of genes are differentially regulated in the various stages of Wallerian degeneration, especially during the early response. In this study, we analyzed gene expression in early Wallerian degeneration of the distal nerve stump at 0, 0.5, 1,6, 12 and 24 hours after rat sciatic nerve injury using gene chip microarrays. We screened for differentially-expressed genes and gene expression patterns. We examined the data for Gene Ontology, and explored the Kyoto EncycLopedia of Genes and Genomes Pathway. This allowed us to identify key regulatory factors and recurrent network motifs. We identified 1 546 differentially-expressed genes and 21 distinct patterns ofgene expression in early Wallerian degeneration, and an enrichment of genes associated with the immune response, acute inflammation, apoptosis, cell adhesion, ion transport and the extracellular matrix. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed components involved in the Jak-STAT, ErbB, transforming growth factor-13, T cell receptor and calcium signaling pathways. Key factors included interleukin-6, interleukin-1, integrin, c-sarcoma, carcinoembryonic antigen-related cell adhesion molecules, chemokine （C-C motif） ligand, matrix metalloproteinase, BH3 interacting domain death agonist, baculoviral lAP repeat-containing 3 and Rac. The data were validated with real-time quantitative PCR. This study provides a global view of gene expression profiles in eady Wallerian degeneration of the rat sciatic nerve. Our findings provide insight into the molecular mechanisms underlying early Wallerian degeneration, and the regulation of nerve degeneration and regeneration.

Basic C Experimental Study on Cheng Zai Wan for Treatment of Necrosis of the Femoral Head

Cheng Zai Wan (承载丸), a Chinese herbal preparation was administrated in the two-leg rat model of asepticnecrosis of the femoral head established by taking prednisone acetate for a long period and the osteoporosismodel rat by castration in order to explore the effects of the prescription on necrosis of the femoral head. Theresults showed that after treatment, the pitting on the surface of the femoral head disappeared, the reticularstructure with filling cells was restored; the fat droplets in bone cells or cartilage cells of the femoral headwere significantly reduced; sparse capillaries were improved, density and width of the bone trabecula wereincreased somewhat; bone mineral density, bone weight, bone strength and rigidity were significantlyincreased; and the low level of estrin was improved. It is suggested that Cheng Zai Wan has definitetherapeutic effects on aseptic necrosis of the femoral head.

Effects of Jisuikang on hemorheology and inflammatory factors in rats following spinal cord injury

BACKGROUND： Trauma can damage the spinal cord or cauda equina to different degrees. Previous studies have verified that traditional Chinese medicine has effects on spinal cord injury via a variety of pathways. OBJECTIVE： To observe changes in hemorheology and inflammatory factors in spinal cord injury rats following treatment with the Chinese medicine Jisuikang, to verify the dose-dependent effect of Jisuikang, and to compare its effects with the effects of prednisone. DESIGN, TIME AND SETTING： A randomized study was performed at the Research Institute of Orthopedics, and Experimental Center of First Clinical Medical College, Nanjing University of Traditional Chinese Medicine, China from September 2007 to March 2008. MATERIALS： Jisuikang powdered extract, composed of milkvetch root （30 g）, Chinese angelica （12 g）, red peony root （12 g）, earthworm （10 g）, szechwan lovage rhizome （10 g）, peach seed （10 g） and safflower （10 g） was provided by the Experimental Center, First Clinical Medical College, Nanjing University of Traditional Chinese medicine. Each gram of powdered extract was equivalent to 6.47 g crude drug. METHODS： A total of 72 Sprague Dawley rats were randomly assigned into 6 groups （n = 12）. Rat models of spinal cord injury were established using the occlusion method. Rats in the model group were treated with distilled water. Rats in the 25 g/kg, 12.5 g/kg, and 6.25 g/kg Jisuikang groups were given 25 g＆g, 12.5 g/kg, or 6.25 g/kg Jisuikang by gavage, for 14 days. Rats in the prednisone group received 0.06 g/kg prednisone by gavage, for 7 days. Rats in the normal group were given the same volume of distilled water. The volume of administration was 15 mL/kg. MAIN OUTCOME MEASURES： Rat serum interleukin-10, tumor necrosis factor- α （TNF-α ）, nitric oxide, nitric oxide synthase levels, malondialdehyde content, superoxide dismutase activity and whole blood viscosity were measured in each group. Spinal cord around the site of the model was collected. Half the spinal cord was used for histopathologic examination. The other half was used for measurement of nitric oxide and NOS levels, malondialdehyde contents, and superoxide dismutase activity. RESULTS： Superoxide dismutase activity was higher in the 25 g/kg Jisuikang group than in the model group Malondialdehyde contents, nitric oxide and NOS levels were lower in the 25 g/kg and 12.5 g/kg Jisuikang groups compared with the model group. Whole blood viscosity was lower in the 25 g/kg and 12.5 g/kg Jisuikang groups compared with the model group （P 〈 0.05-0.01）. Serum TNF- α content was lower in each Jisuikang group compared with the model group （P 〈 0.05-0.01）. Serum interleukin-10 levels were greater in the prednisone group and each Jisuikang group compared with the model group （P 〈 0.01）. Mild hemorrhage and necrosis in the rat spinal cord, and unclear neural cell swelling were seen in the 25 g/kg Jisuikang group： Severe hemorrhage and necrosis in the rat spinal cord, and distinct neural cell swelling were seen in the 12.5 g/kg Jisuikang group. Edema in the white matter was found in the 6.25 g/kg Jisuikang group. Pathological changes in the prednisone group were identical to the 25 g/kg and 12.5 g/kg Jisuikang groups. CONCLUSION： Jisuikang inhibits nitric oxide synthase expression, reduces nitric oxide and TNF-α levels decreases malondialdehyde content, increases interleukin-10 levels and superoxide dismutase activity, improves indices of hemorheology, and prevents secondary changes in spinal cord injury, resulting in relieving pathological changes in spinal cord tissue. The outcome was significant in the 25 g/kg Jisuikang group compared with the 12.5 g/kg Jisuikang group.

Comparison of human amniotic fluid-derived and umbilical cord Wharton＇s Jelly-derived mesenchymal stromal cells： Characterization and myocardial differentiation capacity

Objective To compare the characterization and myocardial differentiation capacity of arnniotic fluid-derived mesenchymal stromal cells （AF MSCs） and umbilical cord Wharton＇s Jelly-derived mesenchymal stromal cells （WJ MSCs）. Methods The human AF MSCs were cultured from amniotic fluid samples obtained by amniocentesis. The umbilical cord WJ MSCs were obtained from Wharton＇s Jelly of umbilical cords of infants delivered full-term by normal labor. The morphology, growth curves, and analyses by flow cytometry of cell surface markers were compared between the two types of cells. Myocardial genes （GATA-4, c-TnT, a-actin, and Cx43） were detected by real-time PCR and the corresponding protein expressions were detected by Western blot analysis after myocardial induced in AF MSCs and WJ MSCs. Results Our findings revealed AF MSCs and WJ MSCs shared similar morphological characteristics of the fibroblastoid shape. The AF MSCs were easily obtained than the WJ MSCs and had a shorter time to reach adherence of 2.7 ± 1.6 days to WJ MSCs of 6.5 ± 1.8 days. The growth curves by MTT cytotoxic assay showed the AF MSCs had a similar proliferative capacity at passage 5 and passage 10. However, the proliferative capacities ofWJ MSCs were decreased at 5 passage relative to 10 passage. Both AF stem cells and WJ stem cells had the characteristics of mesenchymal stromal cells with some characteristics of embryonic stem cells. They express CD29 and CD105, but not CD34. They were positive for Class I major histocompatibility （MHC I） antigens （HLA-ABC）, and were negative, or mildly positive, for MHC Class II （HLA-DR） antigen. Oct-4 was positive in all the two cells types. Both AF MSCs and WJ MSCs could differentiate along myocardium. The differentiation capacities were detected by the expression of GATA-4, c-TnT, a-actin, Cx43 after myocardial induction. Conclusions Both AF MSCs and WJ MSCs have the potential clinical application for myogenesis in cardiac regenerative therapy.

Protein microarray analysis of cytokine expression changes in distal stumps after sciatic nerve transection

A large number of chemokines,cytokines,other trophic factors and the extracellular matrix molecules form a favorable microenvironment for peripheral nerve regeneration.This microenvironment is one of the major factors for regenerative success.Therefore,it is important to investigate the key molecules and regulators affecting nerve regeneration after peripheral nerve injury.However,the identities of specific cytokines at various time points after sciatic nerve injury have not been determined.The study was performed by transecting the sciatic nerve to establish a model of peripheral nerve injury and to analyze,by protein microarray,the expression of different cytokines in the distal nerve after injury.Results showed a large number of cytokines were up-regulated at different time points post injury and several cytokines,e.g.,ciliary neurotrophic factor,were downregulated.The construction of a protein-protein interaction network was used to screen how the proteins interacted with differentially expressed cytokines.Kyoto Encyclopedia of Genes and Genomes pathway and Gene ontology analyses indicated that the differentially expressed cytokines were significantly associated with chemokine signaling pathways,Janus kinase/signal transducers and activators of transcription,phosphoinositide 3-kinase/protein kinase B,and notch signaling pathway.The cytokines involved in inflammation,immune response and cell chemotaxis were up-regulated initially and the cytokines involved in neuronal apoptotic processes,cell-cell adhesion,and cell proliferation were up-regulated at 28 days after injury.Western blot analysis showed that the expression and changes of hepatocyte growth factor,glial cell line-derived neurotrophic factor and ciliary neurotrophic factor were consistent with the results of protein microarray analysis.The results provide a comprehensive understanding of changes in cytokine expression and changes in these cytokines and classical signaling pathways and biological functions during Wallerian degeneration,as well as a basis for potential treatments of peripheral nerve injury.The study was approved by the Institutional Animal Care and Use Committee of the Chinese PLA General Hospital,China(approval number:2016-x9-07)in September 2016.

Dynamic culture of a thermosensitive collagen hydrogel as an extracellular matrix improves the construction of tissue-engineered peripheral nerve

Tissue engineering technologies offer new treatment strategies for the repair of peripheral nerve injury, hut cell loss between seeding and adhesion to the scaffold remains inevitable. A thermosensitive collagen hydrogel was used as an extracellular matrix in this study and combined with bone marrow mesenchymal stem cells to construct tissue-engineered peripheral nerve composites in vitro. Dynamic culture was performed at an oscillating frequency of 0.5 Hz and 35° swing angle above and below the horizontal plane. The results demonstrated that bone marrow mesenchymal stem cells formed membrane-like structures around the poly-L-lactic acid scaffolds and exhibited regular alignment on the composite surface. Collagen was used to fill in the pores, and seeded cells adhered onto the poly-L-lactic acid fibers. The DNA content of the bone marrow mesenchymal stem cells was higher in the composites constructed with a thermosensitive collagen hydrogel compared with that in collagen I scaffold controls. The cellular DNA content was also higher in the thermosensitive collagen hydrogel composites constructed with the thermosensitive collagen hydrogel in dynamic culture than that in static culture. These results indicate that tissue-engineered composites formed with thermosensitive collagen hydrogel in dynamic culture can maintain larger numbers of seeded cells by avoiding cell loss during the initial adhe-sion stage. Moreover, seeded cells were distributed throughout the material.

Different protein expression patterns in rat spinal nerves during wallerian degeneration assessed using isobaric tags for relative and absolute quantitation proteomics profiling

Sensory and motor nerve fibers of peripheral nerves have different anatomies and regeneration functions after injury. To gain a clear understanding of the biological processes behind these differences, we used a labeling technique termed isobaric tags for relative and absolute quantitation to investigate the protein profiles of spinal nerve tissues from Sprague-Dawley rats. In response to Wallerian degeneration, a total of 626 proteins were screened in sensory nerves, of which 368 were upregulated and 258 were downregulated. In addition, 637 proteins were screened in motor nerves, of which 372 were upregulated and 265 were downregulated. All identified proteins were analyzed using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of bioinformatics, and the presence of several key proteins closely related to Wallerian degeneration were tested and verified using quantitative real-time polymerase chain reaction analyses. The differentially expressed proteins only identified in the sensory nerves were mainly relevant to various biological processes that included cell-cell adhesion, carbohydrate metabolic processes and cell adhesion, whereas differentially expressed proteins only identified in the motor nerves were mainly relevant to biological processes associated with the glycolytic process, cell redox homeostasis, and protein folding. In the aspect of the cellular component, the differentially expressed proteins in the sensory and motor nerves were commonly related to extracellular exosomes, the myelin sheath, and focal adhesion. According to the Kyoto Encyclopedia of Genes and Genomes, the differentially expressed proteins identified are primarily related to various types of metabolic pathways. In conclusion, the present study screened differentially expressed proteins to reveal more about the differences and similarities between sensory and motor nerves during Wallerian degeneration. The present findings could provide a reference point for a future investigation into the differences between sensory and motor nerves in Wallerian degeneration and the characteristics of peripheral nerve regeneration. The study was approved by the Ethics Committee of the Chinese PLA General Hospital, China(approval No. 2016-x9-07) in September 2016.

APPLICATION OF FINGER PRESSURE TO ANKLE SPRAINS

Finger pressure is to use fingers insteadof needles to apply manipulations to pointsor channels of the patient.Usually one fin-ger is used:the thumb,the index finger,orthe middle finger,but sometimes 2,3,or 5fingers are used at the same time.

Preparation of polypyrrole-embedded electrospun poly(lactic acid) nanofibrous scaffolds for nerve tissue engineering

Polypyrrole （PPy） is a biocompatible polymer with good conductivity. Studies combining PPy with electrospinning have been reported; however, the associated decrease in PPy conductivity has not yet been resolved. We embedded PPy into poly（lactic acid） （PLA） nanofibers via electrospinning and fabricated a PLA/PPy nanofibrous scaffold containing 15% PPy with sustained conductivity and aligned topog- raphy, qhere was good biocompatibility between the scaffold and human umbilical cord mesenchymal stem cells as well as Schwann cells. Additionally, the direction of cell elongation on the scaffold was parallel to the direction of fibers. Our findings suggest that the aligned PLA/PPy nanofibrous scaffold is a promising biomaterial for peripheral nerve regeneration.

Effects of Ge Gen Decoction on PGE2 Content and COX Activity in the Degenarated Cervical Intervertebral Discs of Rats

After the rat model of cervical spondylosis was developed for 6 months, the PGE2 content and COX activity in the cervical intervertebral discs were determined respectively by radioimmunoassay and catalytic activity assay.The results indicated that the PGF2 content and COX activity in the model rat increased significantly, and that Ge Gen Decoction could down-regulate the PGE2 content and inhibit COX activity. This is possibly one of the mechanisms of Ge Gen Decoction for treating cervical spondylosis.

Synthesis of N-methylene phosphonic chitosan(NMPCS)and its potential as gene carder

N-Methylene phosphonic chitosan （NMPCS）, an amphiphilic macromolecule with powerful chelating ability of Ca^2＋ ions, was synthesized and characterized. The physicochernical properties of NMPCS and the interactions between NMPCS and plasmid DNA were investigated by FTIR, ^13C NMR, X-ray, agarose gel electrophoresis retardation assay, atomic force microscopy （AFM） and circular dichroism （CD）. The results suggest that at charge ratio 2：1 or above, DNA could be completely entrapped and spherical complexes with mean size of 80-210 nm were formed. Taking HeLa as host cell, luciferase expression mediated by NMPCS improved about 100 times compared to the expression mediated by chitosan.

The Effect of Electroacupuncture on Neuronal Apoptosis and Related Functions in Rats with Acute Spinal Cord Injury

Objective: To investigate the effect and significance of electroacupuncture (EA) on neuronal apoptosis and hindlimb motor and bladder functional improvement in rats with acute spinal cord injury (SCI). Methods: Sixty healthy Sprague Dawley rats were randomly assigned to sham, model, EA, and EA control groups (n = 15 each). EA group rats received EA treatment at Zhibian and Shuidao acupoints seven times daily, whereas EA control group rats received EA at two points, 0.5 cm away from Zhibian and Shuidao, respectively. Histomorphological changes in spinal cord tissue were examined using hematoxylin-eosin staining. Neuronal apoptosis was detected by TUNEL assay. Bcl-2, Bax, and Bad protein levels were detected using immunohistochemistry. Additionally, hindlimb motor function, residual urine volume and maximum bladder capacity were measured. Results: HE staining revealed a morphologically and structurally intact spinal cord in the EA group, and the tissue contained scattered blood cells without edema. In the EA control group, there were small morphological defects in the spinal cord, and the tissue contained fewer blood cells with local edema. Compared with the EA control and model groups, Bax and Bad levels were significantly decreased in the EA group and Bcl-2 expression was increased (P < 0.05). After SCI, hindlimb function scores, residual urine volume, and maximum bladder capacity in rats of the EA group significantly differed from those of the EA control group (P < 0.05). Conclusion: EA may induce SCI-induced improvements in hindlimb motor and bladder functions by affecting neuronal apoptosis and relevant gene expression changes.

EFFECTS OF LIUWEIDIHUANG WAN AND SOME OTHER TCM DRUGS ON BONE BIOMECHANICS AND SERUM 25(OH)D_(3) CONTENT IN RATS

After a relatively long-term injection of hydrocortisone into rats, the strength of bone (anti-stress capacity) reduced evidently, while the rigidity (anti-deformity capacity) in-creased markedly (ie, bone fragility elevated). At the same time, the content of serum 25(OH)D3 decreased remarkably. After oral administration of Liuwei Dihuang Wan (六味地黄丸), anti-stress capability of bone increased evidently and its anti-deformity capability returned to normal; however, there was no elevation of serum 25(OH)D3 content The ef-fect of Longmu Zhuanggu Chongji (龙牡壮骨冲剂) or Jisheng Shenqi Wan (济生肾气丸) was lower than that of Linwei Dihuang Wan. The experiments suggest that Liuwei Dihuang Wan is beneficial to preventing and curing osteoporosis, but no correlation between its mechanism and the metabolism of 25(OH)D3 was demonstrated.

Advances in regenerative medicine applications of tetrahedral framework nucleic acid-based nanomaterials: an expert consensus recommendation

With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versatile functions. Especially promising nanostructures are tetrahedral framework nucleic acids(t FNAs), first proposed by Turberfield with the use of a one-step annealing approach. Benefiting from their various merits, such as simple synthesis, high reproducibility, structural stability, cellular internalization, tissue permeability, and editable functionality, t FNAs have been widely applied in the biomedical field as threedimensional DNA nanomaterials. Surprisingly, t FNAs exhibit positive effects on cellular biological behaviors and tissue regeneration,which may be used to treat inflammatory and degenerative diseases. According to their intended application and carrying capacity,t FNAs could carry functional nucleic acids or therapeutic molecules through extended sequences, sticky-end hybridization,intercalation, and encapsulation based on the Watson and Crick principle. Additionally, dynamic t FNAs also have potential applications in controlled and targeted therapies. This review summarized the latest progress in pure/modified/dynamic t FNAs and demonstrated their regenerative medicine applications. These applications include promoting the regeneration of the bone,cartilage, nerve, skin, vasculature, or muscle and treating diseases such as bone defects, neurological disorders, joint-related inflammatory diseases, periodontitis, and immune diseases.

Does repair of spinal cord injury follow the evolutionary theory?

Lower vertebrates, such as fish and amphibians, and higher vertebrates in embryonic development can acquire complete regeneration of complex body structures, including the spinal cord, an important part of the central nervous system. However, with species evolution and development, this regenerative capacity gradually weakens and even disappears, but the cellular and molecular mechanisms remain poorly understood. We explored the differences in mechanisms of spinal cord regeneration capability between lower and higher vertebrates, investigated differences in their cellular and molecular mechanisms and between the spinal cord structures of lower vertebrates and mammals, such as rat and monkey, to search for theoretical evidence and therapeutic targets for nerve regeneration in human spinal cord.