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SummaryOur ultimate goal of in vitro derivation of Schwann cells (SCs) from adult bone marrow stromal cells (BMSCs) is such that they may be used autologously to assist post-traumatic nerve regeneration. Existing protocols for derivation of SC-like cells from BMSCs fall short in the stability of the acquired phenotype and the functional capacity to myelinate axons. Our experiments indicated that neuro-ectodermal progenitor cells among the human hBMSCs could be selectively expanded and then induced to differentiate into SC-like cells. Co-culture of the SC-like cells with embryonic dorsal root ganglion neurons facilitated contact-mediated signaling that accomplished the switch to fate-committed SCs. Microarray analysis and in vitro myelination provided evidence that the human BMSC-derived SCs were functionally mature. This was reinforced by repair and myelination phenotypes observable in vivo with the derived SCs seeded into a nerve guide as an implant across a critical gap in a rat model of sciatic nerve injury.

BackgroundBone marrow stromal cells (BMSCs) are attractive as a source of neural progenitors for ex vivo generation of neurons and glia. Limited numbers of this subpopulation, however, hinder translation into autologous cell-based therapy. Here, we demonstrate rapid and efficient conditioning with hypoxia to enrich for these neural progenitor cells prior to further expansion in neurosphere culture.MethodAdherent cultures of BMSCs (rat/human) were subjected to 1 % oxygen for 24 h and then subcultured as neurospheres with epidermal growth factor (EGF) and basic fibroblast growth factor supplementation. Neurospheres and cell progeny were monitored immunocytochemically for marker expression. To generate Schwann cell-like cells, neurospheres were plated out and exposed to gliogenic medium. The resulting cells were co-cultured with purified dorsal root ganglia (rat) neurons and then tested for commitment to the Schwann cell fate. Fate-committed Schwann cells were subjected to in vitro myelination assay.ResultsTransient hypoxic treatment increased the size and number of neurospheres generated from both rat and human BMSCs. This effect was EGF-dependent and attenuated with the EGF receptor inhibitor erlotinib. Hypoxia did not affect the capacity of neurospheres to generate neuron- or glia-like precursors. Human Schwann cell-like cells generated from hypoxia-treated BMSCs demonstrated expression of S100β /p75 and capacity for myelination in vitro.ConclusionEnhancing the yield of neural progenitor cells with hypoxic preconditioning of BMSCs in vitro but without inherent risks of genetic manipulation provides a platform for upscaling production of neural cell derivatives for clinical application in cell-based therapy.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0409-x) contains supplementary material, which is available to authorized users.

Introduction: Patella fractures managed by fixation with metal implants often cause local soft tissue irritation and necessitate implant removal. An alternative is to utilize suture-based fixation methods. We have adopted suture and hybrid fixation in the routine management of patella fractures. Here, we compare the results of 3 fixation techniques. Materials and Methods: Eighty-seven eligible patients underwent patella fracture fixation over a 3-year period. As determined by fracture configuration, patients received (1) suture fixation (transosseous sutures and figure-of-eight tension banding with FiberWire), (2) hybrid fixation (transosseous FiberWire sutures and metal tension banding), or (3) metal fixation. Primary outcome measures included reoperation rate and soft tissue irritation. Secondary outcomes included surgical complications, radiological, and functional parameters. Results: Reoperation rate was highest for metal fixation (25/57, 43.9%) and lowest for suture fixation (2/13, 15.4%). Soft tissue irritation necessitating implant removal was the predominant reason for reoperation and was significantly less prevalent following suture fixation (1/13, 7.7%, P < .01). Hybrid fixation resulted in similar rates of soft tissue irritation (6/17, 35.3%) and implant removal (7/17, 41.2%) as compared to metal fixation. There was a significant increase in patella baja (13/17, 76.5%) and reduction in Insall-Salvati ratio (0.742; 95% confidence interval: 0.682-0.802) following hybrid fixation as compared to the other 2 fixation methods ( P < .05). Discussion: Suture fixation results in the least amount of soft tissue irritation and lowest reoperation rate, but these advantages are negated with the addition of a metal tension band wire. Hybrid fixation also unbalances the extensor mechanism. Conclusion: Patients should be counseled as to the expected sequelae of their fixation method. Suture fixation is the favored means to fix distal pole fractures of the patella. An additional metal tension band loop may confer additional stability but should be applied with caution.

3D printing in the context of medical application can allow for visualization of patient-specific anatomy to facilitate surgical planning and execution. Intra-operative usage of models and guides allows for real time feedback but ensuring sterility is essential to prevent infection. The additive manufacturing process restricts options for sterilisation owing to temperature sensitivity of thermoplastics utilised for fabrication. Here, we review one of the largest single cohorts of 3D models and guides constructed from Acrylonitrile butadiene styrene (ABS) and utilized intra-operatively, following terminal sterilization with hydrogen peroxide plasma. We describe our work flow from initial software rendering to printing, sterilization, and on-table application with the objective of demonstrating that our process is safe and can be implemented elsewhere. Overall, 7% (8/114 patients) of patients developed a surgical site infection, which was not elevated in comparison to related studies utilizing traditional surgical methods. Prolonged operation time with an associated increase in surgical complexity was identified to be a risk factor for infection. Low temperature plasma-based sterilization depends upon sufficient permeation and contact with surfaces which are a particular challenge when our 3D-printouts contain diffusion-restricted luminal spaces as well as hollows. Application of printouts as guides for power tools may further expose these regions to sterile bodily tissues and result in generation of debris. With each printout being a bespoke medical device, it is important that the multidisciplinary team involved in production and application understand potential pitfalls to ensuring sterility as to minimize infection risk.

Background: Prediction of curve progression risk in adolescent idiopathic scoliosis (AIS) remains elusive. Prior studies have revealed the potential for three-dimensional (3D) morphological parameters to prognosticate progression, but these require specialized biplanar imaging equipment and labor-intensive software reconstruction. This study aimed to formulate a deep learning model with standing posteroanterior (PA) X-rays at first clinic visit to differentiate between progressive (P) and non-progressive (NP) curves. Methods: For this retrospective cohort study, we identified patients presenting with AIS between October 2015 to April 2020 at our tertiary referral centre. Patients with mild curvatures (11 -30 o ) who were skeletally immature (Risser sign of ≤2) were recruited. Patients receiving biplanar X-ray radiographs (EOS™) were divided between a training-cross-validation cohort (328 patients) and independent testing cohort (110 patients). Another 52 patients receiving standard PA spinal X-rays were recruited for cross-platform validation. Following 3D reconstruction, we designated the major curve apex upon PA X-rays as the region of interest (ROI) for machine learning. A self-attentive capsule network was constructed to differentiate between curves manifesting P and NP trajectories. A two-stage transfer learning strategy was introduced to pre-train and fine-tune the model. Model performance (accuracy, sensitivity, specificity) was compared to that of traditional convolutional neural networks (CNNs) and a clinical parameter-based logistic regression model. Findings: 3D reconstruction identified that apical rotation of the major curve and torsion were significantly different between P and NP curve trajectories. Our predictive model utilizing an ROI centered on the major curve apex achieved an accuracy of 76.6%, a sensitivity of 75.2% and a specificity of 80.2% upon independent testing. Cross-platform performance upon standard standing PA X-rays yielded an accuracy of 77.1%, a sensitivity of 73.5% and a specificity of 81.0%. Errors in prediction occurred when the degree of apical rotation / torsion was discrepant from that of the subsequent curve trajectory but could be rectified by considering serial X-rays. Performance was superior to that of traditional CNNs as well as clinical parameter-based regression models. Interpretation: This is the first report of automated prediction of AIS curve progression based on radiomics and deep learning, towards directing treatment strategy at first visit. Patients predicted to be at-risk of progression may be counselled to receive early bracing with enforcement of treatment compliance. Over-treatment may be avoided in curves deemed to be non-progressive. Results need to be consolidated in larger sample populations of different ethnicities. Funding: The Society for the Relief of Disabled Children (SRDC).

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Schwann cells are critically important for tissue repair, axonal regrowth and remyelination following injury to peripheral nerves. The absence of Schwann cells or an equivalent cell type in the central nervous system (CNS) may limit the regeneration capacity of the CNS. Mesenchymal stem cells (MSCs) have therefore been investigated for their potential to be induced to develop a Schwann cell phenotype. The methods for derivation of Schwann cell-like cells from MSCs and the benefits and limitations of each of these methods are presented in this review. Issues related to instability of the derived Schwann cell phenotype, apoptosis of derived cells in transplants, and the inability to predict with confidence how the cells will behave after transplantation are discussed. Finally, we suggest the need for further elucidation of the biology of Schwann cell differentiation and the signals for their derivation from MSC, in order to resolve these obstacles and to enable transplantation of MSC-derived Schwann cells as a therapeutic strategy in CNS injury.