Current methods for studying central nervous system myelination necessitate permissive axonal substrates conducive for myelin wrapping by oligodendrocytes. We have developed a neuron-free culture system in which electron-spun nanofibers of varying sizes substitute for axons as a substrate for oligodendrocyte myelination, thereby allowing manipulation of the biophysical elements of axonal-oligodendroglial interactions. To investigate axonal regulation of myelination, this system effectively uncouples the role of molecular (inductive) cues from that of biophysical properties of the axon. We use this method to uncover the causation and sufficiency of fiber diameter in the initiation of concentric wrapping by rat oligodendrocytes. We also show that oligodendrocyte precursor cells display sensitivity to the biophysical properties of fiber diameter and initiate membrane ensheathment prior to differentiation. The use of nanofiber scaffolds will enable screening for potential therapeutic agents that promote oligodendrocyte differentiation and myelination as well as provide valuable insight into the processes involved in remyelination.

IMPORTANCE During the outbreak of COVID-19, outdoor activities were limited and digital learning increased. Concerns have arisen regarding the impact of these environmental changes on the development of myopia.OBJECTIVE To investigate changes in the development of myopia in young Chinese schoolchildren during the outbreak of COVID-19. DESIGN, SETTING, AND PARTICIPANTSIn this observational study, 2 groups of students from 12 primary schools in Guangzhou, China, were prospectively enrolled and monitored from grade 2 to grade 3. Comparisons between the exposure and nonexposure groups were made to evaluate any association between environmental changes during the COVID-19 outbreak period and development of myopia. The exposure group

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Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form -although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques. Video LinkThe video component of this article can be found at

Electrospinning is a technique for producing micro-to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned to completely random. In addition, fibers can be spun from a variety of materials, including biodegradable polymers such as poly-L-lactic acid (PLLA). These characteristics make electrospun fibers suitable for a variety of scaffolding applications in tissue engineering. Our focus is on the use of aligned electrospun fibers for nerve regeneration. We have previously shown that aligned electrospun PLLA fibers direct the outgrowth of both primary sensory and motor neurons in vitro. We maintain that the use of a primary cell culture system is essential when evaluating biomaterials to model real neurons found in vivo as closely as possible. Here, we describe techniques used in our laboratory to electrospin fibrous scaffolds and culture dorsal root ganglia explants, as well as dissociated sensory and motor neurons, on electrospun scaffolds. However, the electrospinning and/or culture techniques presented here are easily adapted for use in other applications. Video LinkThe video component of this article can be found at https://www.jove.com/video/2389/ Protocol 1. Poly-L-lactic Acid (PLLA) Spinning Solution 1. Dissolve 0.4 g PLLA in 9 mL chloroform by stirring over low heat. 2. Add 1 mL dimethylformamide to the solution, bringing the final concentration of the solution to 4% PLLA (w/v) in chloroform:DMF 9:1 (v/v). 3. Place the solution in a polypropylene or glass syringe with a blunt 23ga metal tip. Spinning Substrate Preparation 11. Make an 8% (w/v) solution of 85:15 PLGA (poly-lactic-co-glycolic acid) in chloroform by stirring over low heat. 2. Coat clean glass cover slips in PLGA by covering the surface of each cover slip with the PLGA solution. Allow the PLGA to dry to a thin film (approx. 30 min). Electrospinning 21. Secure PLGA coated glass cover slips to collector with conductive carbon tape. For aligned fibers, the collector is a motor-driven wheel. For random fibers, the collector is a stationary plate. 2. Place syringe in pump with tip 20 cm from collector wheel. Set pump to approximately 2 mL/hr and if using a wheel, set the motor to 300-400 RPM. If possible, apply a -2 kV DC bias to the collector and +15 kV to metal tip. In the absence of access to a bipolar power supply, ground the collector. 3. Fibers will jet from the syringe tip and collect on the rotating wheel. Continue spinning until the desired density of fibers is obtained. Swipe the metal tip with a paper towel affixed to a non-conductive rod periodically to prevent clogging at the tip.

PurposeTo investigate the 2-year efficacy of atropine, orthokeratology (ortho-k) and combined treatment on myopia. To explore the factors influencing the efficacy.MethodsAn age-stratified randomised controlled trial. Children (n=164) aged 8–12 years with spherical equivalent refraction of −1.00 to −6.00 D were stratified into two age subgroups and randomly assigned to receive placebo drops+spectacles (control), 0.01% atropine+spectacles (atropine), ortho-k+placebo (ortho-k) or combined treatment. Axial length was measured at baseline and visits at 6, 12, 18 and 24 months. The primary analysis was done following the criteria of intention to treat, which included all randomised subjects.ResultsAll interventions can significantly reduce axial elongation at all visits (all p<0.05). Overall, the 2-year axial elongation was significantly reduced in combined treatment than in monotherapies (all p<0.05). After stratification by age, in the subgroup aged 8–10, the difference between combined treatment and ortho-k became insignificant (p=0.106), while in the subgroup aged 10–12, the difference between combined treatment and atropine became insignificant (p=0.121). A significant age-dependent effect existed in the ortho-k group versus the control group (p for interaction=0.013), and a significant age-dependent effect existed in the ortho-k group versus the atropine group (p for interaction=0.035), which indicated that ortho-k can achieve better efficacy in younger children.ConclusionsAtropine combined with ortho-k treatment can improve the efficacy of myopia control compared with monotherapy in children aged 8–12. Younger children might benefit more from ortho-k.Trial registration numberChiCTR1800015541.

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Purpose To develop and validate a standardized prediction model aiming at 1‐year axial length elongation and to guide the orthokeratology lens practice. Methods This retrospective study was based on medical records of myopic children treated with orthokeratology. Individuals aged 8–15 years (n = 1261) were included and divided into the primary cohort (n = 757) and validation cohort (n = 504). Feature selection was primarily performed to sort out influential predictors by high‐throughput extraction. Then, the prediction model was developed using multivariable linear regression analysis completed by backward stepwise selection. Finally, the validation of the prediction model was performed by evaluation metrics (mean‐square error, root‐mean‐square error, mean absolute error and Rad2). Results No significant difference was found between primary and validation cohort (all p > 0.05). After the feature selection, the crude model was adjusted by demographic information in multivariable linear regression analysis, and five final predictors were identified (all p < 0.01). The interaction effect of age with 1‐month change of zone‐3 mm flat K was detected (p < 0.01); hence, two final prediction models were developed based on two age subgroups. The validation proved an acceptable performance. Conclusion An effective multivariable prediction model aiming at 1‐year axial length elongation was developed and validated. It can potentially help clinicians to predict orthokeratology efficacy and make valid adjustments. The influential variables revealed in this model can also provide designers directions to optimize the design of lens to improve the efficacy of myopia control.