Cell Replacement Therapy for Brain Repair: Recent Progress and Remaining Challenges for Treating Parkinson's Disease and Cortical Injury.

Neural transplantation represents a promising approach to repairing damaged brain circuitry. Cellular grafts have been shown to promote functional recovery through "bystander effects" and other indirect mechanisms. However, extensive brain lesions may require direct neuronal replacement to achieve meaningful restoration of function. While fetal cortical grafts have been shown to integrate with the host brain and appear to develop appropriate functional attributes, the significant ethical concerns and limited availability of this tissue severely hamper clinical translation. Induced pluripotent stem cell-derived cells and tissues represent a more readily scalable alternative. Significant progress has recently been made in developing protocols for generating a wide range of neural cell types in vitro. Here, we discuss recent progress in neural transplantation approaches for two conditions with distinct design needs: Parkinson's disease and cortical injury. We discuss the current status and future application of injections of dopaminergic cells for the treatment of Parkinson's disease as well as the use of structured grafts such as brain organoids for cortical repair.

Determination of the Terbium-152 half-life from mass-separated samples from CERN-ISOLDE and assessment of the radionuclide purity.

Terbium-152 is one of four terbium radioisotopes that together form a potential theranostic toolbox for the personalised treatment of tumours. As 152 Tb decay by positron emission it can be utilised for diagnostics by positron emission tomography. For use in radiopharmaceuticals and for activity measurements by an activity calibrator a high radionuclide purity of the material and an accurate and precise knowledge of the half-life is required. Mass-separation and radiochemical purification provide a production route of high purity 152Tb. In the current work, two mass-separated samples from the CERN-ISOLDE facility have been assayed at the National Physical Laboratory to investigate the radionuclide purity. These samples have been used to perform four measurements of the half-life by three independent techniques: high-purity germanium gamma-ray spectrometry, ionisation chamber measurements and liquid scintillation counting. From the four measurement campaigns a half-life of 17.8784(95) h has been determined. The reported half-life shows a significant difference to the currently evaluated half-life (ζ-score = 3.77), with a relative difference of 2.2 % and an order of magnitude improvement in the precision. This work also shows that under controlled conditions the combination of mass-separation and radiochemical separation can provide high-purity 152Tb.

Intelligent Virtual Operating Room for Enhancing Nontechnical Skills.

This article discusses an intelligent immersive virtual operating room to enable teams to train in a distributed fashion wearing head-mounted displays.

Accelerometer-Based Navigation in Primary Total Knee Arthroplasty Leads to Improved Alignment but No Change in Patient-Reported Outcomes.

BACKGROUND: Computer and accelerometer-based navigation (ABN) tools have demonstrated improved mechanical alignment in primary total knee arthroplasty (TKA). ABN, in particular, is attractive due to avoidance of pins and trackers. Prior literature has yet to demonstrate an associated improvement in functional outcomes using ABN compared to conventional instrumentation (CONV). The purpose of this study was to compare alignment and functional outcomes between CONV and ABN in primary TKA in a large patient series. METHODS: A retrospective study of 1,925 TKAs performed by a single surgeon sequentially was performed. There were 1,223 TKAs performed with CONV and measured resection technique. There were 702 TKAs performed with distal femoral ABN and restricted kinematic alignment goals. We compared radiographic alignment, Patient-Reported Outcomes Measurement Information System scores, rates of manipulation under anesthesia, and needs for aseptic revisions between cohorts. Chi-squared, Fisher's exact, and t-tests were used to compare demographics and outcomes. RESULTS: The ABN cohort had higher rates of neutral alignment postoperatively than the CONV cohort (ABN 74% versus CONV 56%, P < .001). Rates of manipulation under anesthesia (ABN 2.8% versus CONV 3.4%, P = .382) and aseptic revision (ABN 0.9% versus CONV 1.6%, P = .189) were similar. The Patient-Reported Outcomes Measurement Information System physical function (ABN 42.6 versus CONV 42.9, P = .4554), physical health (ABN 63.4 versus CONV 63.3, P = .944), mental health (ABN 51.4 versus CONV 52.7, P = .4349), and pain (ABN 32.7 versus CONV 30.9, P = .256) scores were similar. CONCLUSION: ABN is valuable in its ability to improve postoperative alignment but does not improve complication rates or patient-reported functional outcomes.

Modeling Haptic Interactions in Endoscopic Submucosal Dissection (ESD).

The ability to provide realistic haptic feedback is indispensable for virtual-reality (VR) based endoscopic colorectal surgery simulators. Despite its importance, force feedback is commonly simulated by simplified approximations with parameters manually tuned in preliminary evaluations due to the complexity of the dynamics of haptic interaction in colonoscopy interventions. Endoscopic submucosal dissection (ESD) is a particularly challenging intervention that requires advanced manual skills for endoscopic control. This work proposes a mechanical impedance model for haptic interactions in ESD formulated via an experimental methodology applied to endoscopic colorectal interventions in general. The developed model is shown to capture the variations in the interaction force during two operations performed at distinct locations on a porcine sample. Salient cues in the recorded haptic interaction data are presented, and changes in the impedance characteristics of the tool-tissue interaction between the steps of the operation are analyzed.

Implantation of a nerve protector embedded with human GMSC-derived Schwann-like cells accelerates regeneration of crush-injured rat sciatic nerves.

BACKGROUND: Peripheral nerve injuries (PNIs) remain one of the great clinical challenges because of their considerable long-term disability potential. Postnatal neural crest-derived multipotent stem cells, including gingiva-derived mesenchymal stem cells (GMSCs), represent a promising source of seed cells for tissue engineering and regenerative therapy of various disorders, including PNIs. Here, we generated GMSC-repopulated nerve protectors and evaluated their therapeutic effects in a crush injury model of rat sciatic nerves. METHODS: GMSCs were mixed in methacrylated collagen and cultured for 48 h, allowing the conversion of GMSCs into Schwann-like cells (GiSCs). The phenotype of GiSCs was verified by fluorescence studies on the expression of Schwann cell markers. GMSCs encapsulated in the methacrylated 3D-collagen hydrogel were co-cultured with THP-1-derived macrophages, and the secretion of anti-inflammatory cytokine IL-10 or inflammatory cytokines TNF-α and IL-1ß in the supernatant was determined by ELISA. In addition, GMSCs mixed in the methacrylated collagen were filled into a nerve protector made from the decellularized small intestine submucosal extracellular matrix (SIS-ECM) and cultured for 24 h, allowing the generation of functionalized nerve protectors repopulated with GiSCs. We implanted the nerve protector to wrap the injury site of rat sciatic nerves and performed functional and histological assessments 4 weeks post-surgery. RESULTS: GMSCs encapsulated in the methacrylated 3D-collagen hydrogel were directly converted into Schwann-like cells (GiSCs) characterized by the expression of S-100ß, p75NTR, BDNF, and GDNF. In vitro, co-culture of GMSCs encapsulated in the 3D-collagen hydrogel with macrophages remarkably increased the secretion of IL-10, an anti-inflammatory cytokine characteristic of pro-regenerative (M2) macrophages, but robustly reduced LPS-stimulated secretion of TNF-1α and IL-1ß, two cytokines characteristic of pro-inflammatory (M1) macrophages. In addition, our results indicate that implantation of functionalized nerve protectors repopulated with GiSCs significantly accelerated functional recovery and axonal regeneration of crush-injured rat sciatic nerves accompanied by increased infiltration of pro-regenerative (M2) macrophages while a decreased infiltration of pro-inflammatory (M1) macrophages. CONCLUSIONS: Collectively, these findings suggest that Schwann-like cells converted from GMSCs represent a promising source of supportive cells for regenerative therapy of PNI through their dual functions, neurotrophic effects, and immunomodulation of pro-inflammatory (M1)/pro-regenerative (M2) macrophages.

Neurorrhaphy in Presence of Polyethylene Glycol Enables Immediate Electrophysiological Conduction in Porcine Model of Facial Nerve Injury.

Facial nerve trauma often leads to disfiguring facial muscle paralysis. Despite several promising advancements, facial nerve repair procedures often do not lead to complete functional recovery. Development of novel repair strategies requires testing in relevant preclinical models that replicate key clinical features. Several studies have reported that fusogens, such as polyethylene glycol (PEG), can improve functional recovery by enabling immediate reconnection of injured axons; however, these findings have yet to be demonstrated in a large animal model. We first describe a porcine model of facial nerve injury and repair, including the relevant anatomy, surgical approach, and naive nerve morphometry. Next, we report positive findings from a proof-of-concept experiment testing whether a neurorrhaphy performed in conjunction with a PEG solution maintained electrophysiological nerve conduction at an acute time point in a large animal model. The buccal branch of the facial nerve was transected and then immediately repaired by direct anastomosis and PEG application. Immediate electrical conduction was recorded in the PEG-fused nerves (n = 9/9), whereas no signal was obtained in a control cohort lacking calcium chelating agent in one step (n = 0/3) and in the no PEG control group (n = 0/5). Nerve histology revealed putative-fused axons across the repair site, whereas no positive signal was observed in the controls. Rapid electrophysiological recovery following nerve fusion in a highly translatable porcine model of nerve injury supports previous studies suggesting neurorrhaphy supplemented with PEG may be a promising strategy for severe nerve injury. While acute PEG-mediated axon conduction is promising, additional work is necessary to determine if physical axon fusion occurs and the longer-term fate of distal axon segments as related to functional recovery.

Relationship between type 2 diabetes mellitus and markers of cutaneous melanoma aggressiveness: an observational multicentric study in 443 patients with melanoma.

BACKGROUND: Some studies have suggested a relationship between type 2 diabetes mellitus (T2DM) and increased incidence of melanoma. Efforts are under way to identify preventable and treatable factors associated with greater melanoma aggressiveness, but no studies to date have examined the relationship between T2DM and the aggressiveness of cutaneous melanoma at diagnosis. OBJECTIVES: To explore potential associations between T2DM, glycaemic control and metformin treatment and the aggressiveness of cutaneous melanoma. METHODS: We conducted a cross-sectional multicentric study in 443 patients diagnosed with cutaneous melanoma. At diagnosis, all patients completed a standardized protocol, and a fasting blood sample was extracted to analyse their glucose levels, glycated haemoglobin concentration and markers of systemic inflammation. Melanoma characteristics and aggressiveness factors [Breslow thickness, ulceration, tumour mitotic rate (TMR), sentinel lymph node (SLN) involvement and tumour stage] were also recorded. RESULTS: The mean (SD) age of the patients was 55·98 (15·3) years and 50·6% were male. The median Breslow thickness was 0·85 mm. In total, 48 (10·8%) patients were diagnosed with T2DM and this finding was associated with a Breslow thickness > 2 mm [odds ratio (OR) 2·6, 95% confidence interval (CI) 1·4-4·9; P = 0·004)] and > 4 mm (OR 3·6, 95% CI 1·7-7·9; P = 0·001), TMR > 5 per mm2 (OR 4·5, 95% CI 1·4-13·7; P = 0·009), SLN involvement (OR 2·3, 95% CI 1-5·7; P = 0·038) and tumour stages III-IV (vs. I-II) (OR 3·4, 95% CI 1·6-7·4; P = 0·002), after adjusting for age, sex, obesity, alcohol intake and smoking habits. No significant associations emerged between glycated haemoglobin levels, metformin treatment and melanoma aggressiveness. CONCLUSIONS: T2DM, rather than glycaemic control and metformin treatment, is associated with increased cutaneous melanoma aggressiveness at diagnosis.

Endoscopic submucosal dissection: a cognitive task analysis framework toward training design.

BACKGROUND: One of the major impediments to the proliferation of endoscopic submucosal dissection (ESD) training in Western countries is the lack of sufficient experts as instructors. One way to address this gap is to develop didactic systems, such as surgical simulators, to support the role of trainers. Cognitive task analysis (CTA) has been used in healthcare for the design and improvement of surgical training programs, and therefore can potentially be used for design of similar systems for ESD. OBJECTIVE: The aim of the study was to apply a CTA-based approach to identify the cognitive aspects of performing ESD, and to generate qualitative insights for training. MATERIALS AND METHODS: Semi-structured interviews were designed based on the CTA framework to elicit knowledge of ESD practitioners relating to the various tasks involved in the procedure. Three observations were conducted of expert ESD trainers either while they performed actual ESD procedures or at a training workshop. Interviews were either conducted over the phone or in person. Interview participants included four experts and four novices. The observation notes and interviews were analyzed for emergent qualitative themes and relationships. RESULTS: The qualitative analysis yielded thematic insights related to four main cognition-related categories: learning goals/principles, challenges/concerns, strategies, and decision-making. The specific insights under each of these categories were systematically mapped to the various tasks inherent to the ESD procedure. CONCLUSIONS: The CTA approach was applied to identify cognitive themes related to ESD procedural tasks. Insights developed based on the qualitative analysis of interviews and observations of ESD practitioners can be used to inform the design of ESD training systems, such as virtual reality-based simulators.

Biomaterial-mediated reprogramming of monocytes via microparticle phagocytosis for sustained modulation of macrophage phenotype.

Monocyte-derived macrophages orchestrate tissue regeneration by homing to sites of injury, phagocytosing pathological debris, and stimulating other cell types to repair the tissue. Accordingly, monocytes have been investigated as a translational and potent source for cell therapy, but their utility has been hampered by their rapid acquisition of a pro-inflammatory phenotype in response to the inflammatory injury microenvironment. To overcome this problem, we designed a cell therapy strategy where monocytes are exogenously reprogrammed by intracellularly loading the cells with biodegradable microparticles containing an anti-inflammatory drug in order to modulate and maintain an anti-inflammatory phenotype over time. To test this concept, poly(lactic-co-glycolic) acid microparticles were loaded with the anti-inflammatory drug dexamethasone (Dex) and administered to primary human monocytes for four hours to facilitate phagocytic uptake. After removal of non-phagocytosed microparticles, microparticle-loaded monocytes differentiated into macrophages and stored the microparticles intracellularly for several weeks in vitro, releasing drug into the extracellular environment over time. Cells loaded with intracellular Dex microparticles showed decreased expression and secretion of inflammatory factors even in the presence of pro-inflammatory stimuli up to 7 days after microparticle uptake compared to untreated cells or cells loaded with blank microparticles, without interfering with phagocytosis of tissue debris. This study represents a new strategy for long-term maintenance of anti-inflammatory macrophage phenotype using a translational monocyte-based cell therapy strategy without the use of genetic modification. Because of the ubiquitous nature of monocyte-derived macrophage involvement in pathology and regeneration, this strategy holds potential as a treatment for a vast number of diseases and disorders. STATEMENT OF SIGNIFICANCE: We report a unique and translational strategy to overcome the challenges associated with monocyte- and macrophage-based cell therapies, in which the cells rapidly take on inflammatory phenotypes when administered to sites of injury. By intracellularly loading monocytes with drug-loaded microparticles prior to administration via phagocytosis, we were able to inhibit inflammation while preserving functional behaviors of human primary macrophages derived from those monocytes up to seven days later. To our knowledge, this study represents the first report of reprogramming macrophages to an anti-inflammatory phenotype without the use of genetic modification.

Acute drivers of neuroinflammation in traumatic brain injury.

Neuroinflammation is initiated as a result of traumatic brain injury and can exacerbate evolving tissue pathology. Immune cells respond to acute signals from damaged cells, initiate neuroinflammation, and drive the pathological consequences over time. Importantly, the mechanism(s) of injury, the location of the immune cells within the brain, and the animal species all contribute to immune cell behavior following traumatic brain injury. Understanding the signals that initiate neuroinflammation and the context in which they appear may be critical for understanding immune cell contributions to pathology and regeneration. Within this paper, we review a number of factors that could affect immune cell behavior acutely following traumatic brain injury.

Modulation of macrophage phenotype via phagocytosis of drug-loaded microparticles.

Monocyte-derived macrophages play a critical role in directing wound pathology following injury. Depending on their phenotype, macrophages also promote tissue regeneration. However, the therapeutic administration of macrophages with a controlled phenotype is challenging because macrophages are highly plastic and quickly revert to a detrimental, inflammatory phenotype in response to the environment of a damaged tissue. To address this issue, we developed a novel strategy to modulate macrophage phenotype intracellularly through phagocytosis of drug-loaded microparticles. Poly(lactic-co-glycolic acid) microparticles loaded with the anti-inflammatory drug dexamethasone (Dex) were phagocytosed by monocytes and stored intracellularly for at least 5 days. After differentiation into macrophages, cell phenotype was characterized over time with high-throughput gene expression analysis via NanoString. We found that the microparticles modulated macrophage phenotype for up to 7 days after microparticle uptake, with decreases in inflammation-related genes at early timepoints and upregulation of homing- and phagocytosis-related genes at multiple timepoints in a manner similar to cells treated with continuous free Dex. These data suggest that intracellularly loading macrophages with Dex microparticles via phagocytosis could be a unique methodology to selectively modulate macrophage phenotype over time. This strategy would allow therapeutic administration of macrophages for the treatment of a number of inflammatory disease and disorders. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1213-1224, 2019.

Tissue engineered nigrostriatal pathway for treatment of Parkinson's disease.

The classic motor deficits of Parkinson's disease are caused by degeneration of dopaminergic neurons in the substantia nigra pars compacta, resulting in the loss of their long-distance axonal projections that modulate the striatum. Current treatments only minimize the symptoms of this disconnection as there is no approach capable of replacing the nigrostriatal pathway. We are applying microtissue engineering techniques to create living, implantable constructs that mimic the architecture and function of the nigrostriatal pathway. These constructs consist of dopaminergic neurons with long axonal tracts encased within hydrogel microcolumns. Microcolumns were seeded with dopaminergic neuronal aggregates, while lumen extracellular matrix, growth factors, and end targets were varied to optimize cytoarchitecture. We found a 10-fold increase in axonal outgrowth from aggregates versus dissociated neurons, resulting in remarkable axonal lengths of over 6 mm by 14 days and 9 mm by 28 days in vitro. Axonal extension was also dependent upon lumen extracellular matrix, but did not depend on growth factor enrichment or neuronal end target presence. Evoked dopamine release was measured via fast scan cyclic voltammetry and synapse formation with striatal neurons was observed in vitro. Constructs were microinjected to span the nigrostriatal pathway in rats, revealing survival of implanted neurons while maintaining their axonal projections within the microcolumn. Lastly, these constructs were generated with dopaminergic neurons differentiated from human embryonic stem cells. This strategy may improve Parkinson's disease treatment by simultaneously replacing lost dopaminergic neurons in the substantia nigra and reconstructing their long-projecting axonal tracts to the striatum.

3D bio-printed scaffold-free nerve constructs with human gingiva-derived mesenchymal stem cells promote rat facial nerve regeneration.

Despite the promising neuro-regenerative capacities of stem cells, there is currently no licensed stem cell-based product in the repair and regeneration of peripheral nerve injuries. Here, we explored the potential use of human gingiva-derived mesenchymal stem cells (GMSCs) as the only cellular component in 3D bio-printed scaffold-free neural constructs that were transplantable to bridge facial nerve defects in rats. We showed that GMSCs have the propensity to aggregate into compact 3D-spheroids that could produce their own matrix. When cultured under either 2D- or 3D-collagen scaffolds, GMSC spheroids were found to be more capable of differentiating into both neuronal and Schwann-like cells than their adherent counterparts. Using a scaffold-free 3D bio-printer system, nerve constructs were printed from GMSC spheroids in the absence of exogenous scaffolds and allowed to mature in a bioreactor. In vivo transplantation of the GMSC-laden nerve constructs promoted regeneration and functional recovery when used to bridge segmental defects in rat facial nerves. Our findings suggest that GMSCs represent an easily accessible source of MSCs for 3D bio-printing of scaffold-free nervous tissue constructs with promising potential application for repair and regeneration of peripheral nerve defects.

To reverse or not to reverse? A systematic review of autograft polarity on functional outcomes following peripheral nerve repair surgery.

BACKGROUND: The literature describing the best clinical practice for proximal-distal autograft orientation, otherwise known as nerve graft polarity, is inconsistent. With existing disparities in the peripheral nerve literature, the clinical question remains whether reversing nerve autograft polarity bears an advantage for nerve regeneration. METHODS: A comprehensive review of the literature using Embase and PubMed databases (1940-June 2015) was performed to retrieve all original articles on the effects of nerve autograft polarity on nerve regeneration and functional recovery following primary repair of peripheral nerve defects. RESULTS: The initial database search yielded 318 titles. Duplicate exclusion, title review and full text review yielded six articles which directly compared nerve autograft polarity. Histological, morphometric, electrophysiological, and behavioral outcomes were reviewed. All retained articles were animal studies, of which none demonstrated significant differences in outcomes between the normal and reversed polarity groups. A reversed graft may ensure that regenerating nerve fibers are not lost at branching points, however this may not translate into improved function. CONCLUSION: There is insufficient data to suggest that nerve autograft polarity has an impact on nerve regeneration and functional outcomes.

A Porcine Model of Traumatic Brain Injury via Head Rotational Acceleration.

Unique from other brain disorders, traumatic brain injury (TBI) generally results from a discrete biomechanical event that induces rapid head movement. The large size and high organization of the human brain makes it particularly vulnerable to traumatic injury from rotational accelerations that can cause dynamic deformation of the brain tissue. Therefore, replicating the injury biomechanics of human TBI in animal models presents a substantial challenge, particularly with regard to addressing brain size and injury parameters. Here we present the historical development and use of a porcine model of head rotational acceleration. By scaling up the rotational forces to account for difference in brain mass between swine and humans, this model has been shown to produce the same tissue deformations and identical neuropathologies found in human TBI. The parameters of scaled rapid angular accelerations applied for the model reproduce inertial forces generated when the human head suddenly accelerates or decelerates in falls, collisions, or blunt impacts. The model uses custom-built linkage assemblies and a powerful linear actuator designed to produce purely impulsive non-impact head rotation in different angular planes at controlled rotational acceleration levels. Through a range of head rotational kinematics, this model can produce functional and neuropathological changes across the spectrum from concussion to severe TBI. Notably, however, the model is very difficult to employ, requiring a highly skilled team for medical management, biomechanics, neurological recovery, and specialized outcome measures including neuromonitoring, neurophysiology, neuroimaging, and neuropathology. Nonetheless, while challenging, this clinically relevant model has proven valuable for identifying mechanisms of acute and progressive neuropathologies as well as for the evaluation of noninvasive diagnostic techniques and potential neuroprotective treatments following TBI.

Transplantable living scaffolds comprised of micro-tissue engineered aligned astrocyte networks to facilitate central nervous system regeneration.

UNLABELLED: Neurotrauma, stroke, and neurodegenerative disease may result in widespread loss of neural cells as well as the complex interconnectivity necessary for proper central nervous system function, generally resulting in permanent functional deficits. Potential regenerative strategies involve the recruitment of endogenous neural stem cells and/or directed axonal regeneration through the use of tissue engineered "living scaffolds" built to mimic features of three-dimensional (3-D) in vivo migratory or guidance pathways. Accordingly, we devised a novel biomaterial encasement scheme using tubular hydrogel-collagen micro-columns that facilitated the self-assembly of seeded astrocytes into 3-D living scaffolds consisting of long, cable-like aligned astrocytic networks. Here, robust astrocyte alignment was achieved within a micro-column inner diameter (ID) of 180µm or 300-350µm but not 1.0mm, suggesting that radius of curvature dictated the extent of alignment. Moreover, within small ID micro-columns, >70% of the astrocytes assumed a bi-polar morphology, versus ∼10% in larger micro-columns or planar surfaces. Cell-cell interactions also influenced the aligned architecture, as extensive astrocyte-collagen contraction was achieved at high (9-12×10(5)cells/mL) but not lower (2-6×10(5)cells/mL) seeding densities. This high density micro-column seeding led to the formation of ultra-dense 3-D "bundles" of aligned bi-polar astrocytes within collagen measuring up to 150µm in diameter yet extending to a remarkable length of over 2.5cm. Importantly, co-seeded neurons extended neurites directly along the aligned astrocytic bundles, demonstrating permissive cues for neurite extension. These transplantable cable-like astrocytic networks structurally mimic the glial tube that guides neuronal progenitor migration in vivo along the rostral migratory stream, and therefore may be useful to guide progenitor cells to repopulate sites of widespread neurodegeneration. STATEMENT OF SIGNIFICANCE: This manuscript details our development of novel micro-tissue engineering techniques to generate robust networks of longitudinally aligned astrocytes within transplantable micro-column hydrogels. We report a novel biomaterial encasement scheme that facilitated the self-assembly of seeded astrocytes into long, aligned regenerative pathways. These miniature "living scaffold" constructs physically emulate the glial tube - a pathway in the brain consisting of aligned astrocytes that guide the migration of neuronal progenitor cells - and therefore may facilitate directed neuronal migration for central nervous system repair. The small size and self-contained design of these aligned astrocyte constructs will permit minimally invasive transplantation in models of central nervous system injury in future studies.

Advanced biomaterial strategies to transplant preformed micro-tissue engineered neural networks into the brain.

OBJECTIVE: Connectome disruption is a hallmark of many neurological diseases and trauma with no current strategies to restore lost long-distance axonal pathways in the brain. We are creating transplantable micro-tissue engineered neural networks (micro-TENNs), which are preformed constructs consisting of embedded neurons and long axonal tracts to integrate with the nervous system to physically reconstitute lost axonal pathways. APPROACH: We advanced micro-tissue engineering techniques to generate micro-TENNs consisting of discrete populations of mature primary cerebral cortical neurons spanned by long axonal fascicles encased in miniature hydrogel micro-columns. Further, we improved the biomaterial encasement scheme by adding a thin layer of low viscosity carboxymethylcellulose (CMC) to enable needle-less insertion and rapid softening for mechanical similarity with brain tissue. MAIN RESULTS: The engineered architecture of cortical micro-TENNs facilitated robust neuronal viability and axonal cytoarchitecture to at least 22 days in vitro. Micro-TENNs displayed discrete neuronal populations spanned by long axonal fasciculation throughout the core, thus mimicking the general systems-level anatomy of gray matter-white matter in the brain. Additionally, micro-columns with thin CMC-coating upon mild dehydration were able to withstand a force of 893 ± 457 mN before buckling, whereas a solid agarose cylinder of similar dimensions was predicted to withstand less than 150 µN of force. This thin CMC coating increased the stiffness by three orders of magnitude, enabling needle-less insertion into brain while significantly reducing the footprint of previous needle-based delivery methods to minimize insertion trauma. SIGNIFICANCE: Our novel micro-TENNs are the first strategy designed for minimally invasive implantation to facilitate nervous system repair by simultaneously providing neuronal replacement and physical reconstruction of long-distance axon pathways in the brain. The micro-TENN approach may offer the ability to treat several disorders that disrupt the connectome, including Parkinson's disease, traumatic brain injury, stroke, and brain tumor excision.

Achieving and Sustaining Zero: Preventing Surgical Site Infections After Isolated Coronary Artery Bypass With Saphenous Vein Harvest Site Through Implementation of a Staff-Driven Quality Improvement Process.

BACKGROUND: Surgical site infections (SSI) increase morbidity and mortality, hospital costs, length of stay, readmissions, and risk of litigation and may impact a facility's reputation. METHODS: Through implementation of a Six Sigma, interdisciplinary team process and the Contextual Model for change engaged all stakeholders. A total of 44 perioperative processes were evaluated, with 15 processes ultimately altered. Revisions involved identifying inconsistent implementation of procedures and standardizing processes, as well as utilizing new suture techniques and products including disposable electrocardiogram leads and pacing wires, antibiotic-coated sutures, and silver-impregnated midsternal dressings. RESULTS: In isolated coronary artery bypass grafting with donor-site procedures, an incidence of 3.74 per 100 procedures was reduced to 0.7 and ultimately to 0. No patients who underwent coronary artery bypass grafting developed a deep sternal wound infection in over 30 months and 590 procedures, resulting in an estimated cost savings of more than $600 000, from May 2012 through December 2014. CONCLUSIONS: A significant reduction in deep sternal wound infections was achieved by working at all levels of the organization through a multidisciplinary approach to create sustained change. Using real-time observations for current practices, areas for improvement were identified. By engaging frontline staff in the process, ownership of the outcomes and adherence to practice change were promoted. The result was a dramatic, rapid, and sustainable improvement in the prevention of deep sternal wound infection.