A novel flexible nerve guidance conduit promotes nerve regeneration while providing excellent mechanical properties

Autografting is the gold standard for surgical repair of nerve defects>5 mm in length;however,autografting is associated with potential complications at the nerve donor site.As an alternative,nerve guidance conduits may be used.The ideal conduit should be flexible,resistant to kinks and lumen collapse,and provide physical cues to guide nerve regeneration.We designed a novel flexible conduit using electrospinning technology to create fibers on the innermost surface of the nerve guidance conduit and employed melt spinning to align them.Subsequently,we prepared disordered electrospun fibers outside the aligned fibers and helical melt-spun fibers on the outer wall of the electrospun fiber lumen.The presence of aligned fibers on the inner surface can promote the extension of nerve cells along the fibers.The helical melt-spun fibers on the outer surface can enhance resistance to kinking and compression and provide stability.Our novel conduit promoted nerve regeneration and functional recovery in a rat sciatic nerve defect model,suggesting that it has potential for clinical use in human nerve injuries.

Electrical and Piezoresistive Properties of Steel Fiber Cement-based Composites Aligned by a Magnetic Field

Directionally distributed steel fiber cement-based composites(SFCCs)were prepared by magnetic field(MF)induction technology.The orientation factor of steel fibers in the as-obtained SFCCs was determined.Besides,the electrical resistivity and piezoresistive responses in two directions of aligned steel fiber cement-based composites,i e,parallel and perpendicular to MF,were measured.The effects of several variables,eg,steel fiber content,curing age,humidity,and temperature,on anisotropic electrical property were studied.The cyclic and failure piezoresistive responses in different directions were tested.It is found that the aligned steel fibers in the as-obtained SFCCs have a high orientation factor more than 0.88.Besides,SFCCs with aligned steel fibers exhibit an obvious anisotropic conductivity and piezoelectric sensitivity.The electrical conductivity of SFCCs with aligned steel fibers is less affected by temperature and humidity.At the steel fiber content of 2.5wt%,the piezoelectric sensitivity coefficient of SFCCs in the direction parallel to MF has the highest value of 324.14.In addition,the piezoresistive properties of SFCCs with aligned steel fibers in the direction parallel to MF indicate excellent sensitivity and stability under cyclic loading and monotonic loading.

A biomimetic basementmembrane consisted of hybrid aligned nanofibers andmicrofibers with immobilized collagen IV and laminin for rapid endothelialization

Rapid formation of a continuous endothelial cell(EC)monolayer with healthy endothelium function on the luminal surface of vascular implants is imperative to improve the longtime patency of small-diameter vascular implants.In the present study,we combined the contact guidance effects of aligned nanofibers,which enhance EC adhesion and proliferation because of its similar fiber scale with native vascular basement membranes,and aligned microfibers,which could induce EC elongation effectively and allow ECs infiltration.It was followed by successive immobilization of collagen IV and laminin to fabricate a biomimetic basement membrane(BBM)with structural and compositional biomimicry.The hemolysis assay and platelet adhesion results showed that the BBM exhibited excellent hemocompatibility.Meanwhile,the adhered human umbilical vein endothelial cells(HUVECs)onto theBBMaligned along the orientation of the microfibers with an elongated morphology,and the data demonstrated that the BBM showed favorable effects on EC attachment,proliferation,and viability.The oriented EC monolayer formed on the BBM exhibited improved antithrombotic capability as indicated by higher production of nitric oxide and prostacyclin(PGI2).Furthermore,fluorescence images indicated that HUVECs could infiltrate into the BBM,implying theBBM’s ability to enhance transmural endothelialization.Hence,theBBMpossessed the properties to regulate ECbehaviors and allow transmural ingrowth,demonstrating the potential to be applied as the luminal surface of small-diameter vascular implants for rapid endothelialization.

Aligned Fibrous Scaffold Induced Aligned Growth of Corneal Stroma Cells in vitro Culture

To investigate the contribution of fibre arrangement to guiding the aligned growth of corneal stroma cells,aligned and randomly oriented fibrous scaffolds of gelatin and poly-L-lactic acid（PLLA） were fabricated by electrospinning.A comparative study of two different systems with corneal stroma cells on randomly organized and aligned fibres were conducted.The efficiency of the scaffolds for inducing the aligned growth of cells was assessed by morphological observation and 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl-tetrazolium bromide（MTT） assay.Results show that the cells cultured on both randomly oriented and aligned scaffolds maintained normal morphology and well spreading as well as long term proliferation.Importantly,corneal stroma cells grew high orderly on the aligned scaffold,while the cells grew disordered on the randomly oriented scaffold.Moreover,the cells exhibited higher viability in aligned scaffold than that in randomly oriented scaffold.These results indcate that electrospinng to prepare aligned fibrous scaffolds has provided an effective approach to the aligned growth of corneal stroma cells in vitro.Our findings that fiber arrangement plays a crucial role in guiding the aligned growth of cells may be helpful to the development of better biomaterials for tissue engineered cornea.

Fabrication and characterisation of random and aligned electrospun scaffolds to investigate hypothalamic stem/progenitor cell behaviour

Tanycytes are stem/progenitor cells that reside in the hypothalamus of the adult vertebrate brain.Tanycytes can be cultured as free-floating neurospheres in vitro but tend to spontaneously differentiate over time.Here we asked whether morphological cues provided by engineered polymer scaffolds can modify spontaneous differentiation.Tanycyte-derived neurospheres were cultured on electrospun scaffolds,prepared with either random or aligned fiber morphologies.Cells dispersed widely on the scaffolds,and-on aligned scaffolds-were highly organized,orientated parallel to the fibers.Immunocytochemical analysis showed that cells cultured on aligned scaffolds showed significantly greater expression of the neural stem/progenitor cell marker,NrCAM and reduced expres-sion of differentiated cell markers in comparison to those cultured on random scaffolds.Together this shows that tanycytes respond to local engineered cues,and that a morphologically constrained environment can better main-tain tanycytes as stem cells.The aligned scaffold culture system provides a powerful tool to better investigate this novel stem/progenitor cell population.

Electrospun Aligned PCL/Gelatin Scaffolds Mimicking the Skin ECM for Effective Antimicrobial Wound Dressings

Bacterial infections and multidrug-resistant bacteria are major health burdens in wound care.Biocompatible antimicrobial agents,e.g.,ε-polylysine(ε-PL),provide a broad spectrum of antibacterial properties and support dermal cell growth.Here,ε-PL was incorporated into polycaprolactone(PCL)/gelatin electrospun scaffolds collected at varying rotation speeds.Then,the samples were crosslinked using dopamine hydrochloride to provide highly proliferative dressings with broad antimicrobial activity.The morphological study showed that the electrospun wound dressings were smooth,continuous,and bead-free,with a mean diameter ranging from 267±7 to 331±8 nm for all random and aligned nanofibers.The fiber alignment of the electrospun PCL/gelatin scaffolds improved their tensile strength and modulus.Moreover,nanofiber mats are highly hydro-philic,which is crucial for an efficient wound dressing.The samples also demonstrated high antimicrobial properties against common wound bacterial strains,including methicillin-resistant Staphylococcus aureus(MRSA),Staphylococcus aureus(SA),Escherichia coli(EC),Acinetobacter baumannii(AB),and Pseudomonas aeruginosa(PA).Mammalian cell prolifera-tion and morphology assays involving primary human dermal fibroblasts(hDFs)and immortalized keratinocytes(HaCaT)showed excellent biocompatibility of the electrospun mats and remarkably aligned mats.Furthermore,aligned mats showed more cell migration than randomly oriented mats,which is desirable for more efficient wound healing.Therefore,it can be concluded that aligned PCL/gelatin mats containingε-PL are promising for potential use in wound dressings.