Adipose Tissue Uses in Peripheral Nerve Surgery

Currently, many different techniques exist for the surgical repair of peripheral nerves. The degree of injury dictates the repair and, depending on the defect or injury of the peripheral nerve, plastic surgeons can perform nerve repairs, grafts, and transfers. All the previously listed techniques are routinely performed in human patients, but a novel addition to these peripheral nerve surgeries involves concomitant fat grafting to the repair site at the time of surgery. Fat grafting provides adipose-derived stem cells to the injury site. Though fat grafting is performed as an adjunct to some peripheral nerve surgeries, there is no clear evidence as to which procedures have improved outcomes resultant from concomitant fat grafting. This review explores the evidence presented in various animal studies regarding outcomes of fat grafting at the time of various types of peripheral nerve surgery.

Astrocyte and Oligodendrocyte Responses From the Subventricular Zone After Injury

Under normal conditions, neural stem cells (NSCs or B cells) in the adult subventricular zone (SVZ) give rise to amplifying neural progenitor cells (NPCs or C cells), which can produce neuroblasts (or A cells) that migrate to the olfactory bulb and differentiate into new neurons. However, following brain injury, these cells migrate toward the injury site where they differentiate into astrocytes and oligodendrocytes. In this review, we will focus on recent findings that chronicle how astrocytes and oligodendrocytes derived from SVZ-NSCs respond to different types of injury. We will also discuss molecular regulators of SVZ-NSC proliferation and their differentiation into astrocytes and oligodendrocytes. Overall, the goal of this review is to highlight how SVZ-NSCs respond to injury and to summarize the regulatory mechanisms that oversee their glial response. These molecular and cellular processes will provide critical insights needed to develop strategies to promote brain repair following injury using SVZ-NSCs.

Localized, time-dependent responses of rat cranial bone to repeated mild traumatic brain injuries

While it is well-established that bone responds dynamically to mechanical loading, the effects of mild traumatic brain injury (mTBI) on cranial bone composition are unclear. We hypothesized that repeated mTBI (rmTBI) would change the microstructure of cranial bones, without gross skull fractures. To address this, young adult female Piebald Viral Glaxo rats received sham, 1x, 2x or 3x closed-head mTBIs delivered at 24h intervals, using a weight drop device custom built for reproducible impact. Skull bones were collected at 2 or 10 weeks after the final injury/sham procedure, imaged by micro computed tomography and analyzed at predetermined regions of interest. In the interparietal bone, proximal to the injury site, modest increases in bone thickness was observed at 2 weeks, particularly following 3x mTBI. By 10 weeks, 2x mTBI induced a robust increase in the volume and thickness of the interparietal bone, alongside a corresponding decrease in the volume of marrow cavities in the diploe region. In contrast, neither parietal nor frontal skull samples were affected by rmTBI. Our findings demonstrate time- and location-dependent effects of rmTBI on cranial bone structure, highlighting a need to consider microstructural alterations to cranial bone when assessing the consequences of rmTBI.

Detection and Analysis of Perfusion Pressure through Measuring Oxygen Saturation and Requirement of Dural Incision Decompression after Laminectomy

Background. Traumatic spinal cord injury (SCI) can continue and transform long after the time of initial injury. Preventing secondary injury after SCI is one of the most significant challenges, and early intervention to return the blood flow at the injury site can minimize the likelihood of secondary injury. Objective. The purpose of this study is to investigate whether laminectomy can achieve the spinal cord blood flow by measuring the spinal blood oxygen saturation intraoperatively without the presence of light. Methods. Between June and August 2021, eight patients were admitted after traumatic spinal cord injury for surgical treatment. We explored the effectiveness of laminectomy and whether the patients required further procedures or not. We used a brain oxygen saturation monitor at the spine injury site under dark conditions. Results. Eight cervical trauma patients, six males and two females, underwent laminectomy decompression. Three patients’ ASIA grade improved by one level, and one patient showed slight motor-sensory improvement. Oxygen saturation was in the normal range. Conclusion. Performing bony decompression can show good results. Therefore, finding an examination method to confirm the improvement of blood perfusion by measuring oxygen saturation at the injury site after laminectomy is essential to avoid other complications.

Neural Stem Cells: Promoting Axonal Regeneration and Spinal Cord Connectivity

Spinal cord injury (SCI) leads to irreversible functional impairment caused by neuronal loss and the disruption of neuronal connections across the injury site. While several experimental strategies have been used to minimize tissue damage and to enhance axonal growth and regeneration, the corticospinal projection, which is the most important voluntary motor system in humans, remains largely refractory to regenerative therapeutic interventions. To date, one of the most promising pre-clinical therapeutic strategies has been neural stem cell (NSC) therapy for SCI. Over the last decade we have found that host axons regenerate into spinal NSC grafts placed into sites of SCI. These regenerating axons form synapses with the graft, and the graft in turn extends very large numbers of new axons from the injury site over long distances into the distal spinal cord. Here we discuss the pathophysiology of SCI that makes the spinal cord refractory to spontaneous regeneration, the most recent findings of neural stem cell therapy for SCI, how it has impacted motor systems including the corticospinal tract and the implications for sensory feedback.

Ca2+ activity is required for injury-induced migration of microglia

Objectives: Microglia are the resident immune cells in the brain. Brain injury can activate the microglia and induce its directional migration towards injury sites for exerting immune functions. While extracellular ATP released from the injury site mediates the directionality of activated microglia's migration, what endows activated microglia with migration capability remains largely unexplored. Methods: In the present study, we used the larval zebrafish as an in vivo model to visualize the dynamics of both morphology and Ca2+ activity of microglia during its migration evoked by local brain injury. Results: We found that, in response to local injury, activated microglia exhibited an immediate Ca2+ transient and later elevated Ca2+ bursts frequency during its migration towards the local injury site (P < 0.01). Furthermore, suppression of Ca2+ activities significantly retarded microglial migration (P < 0.05). Conclusion: Thus, our study suggests that intracellular Ca2+ activity is required for activated microglia's migration.

Pathogen Reduced Cryoprecipitate and Fibrinogen Concentrate Have Delayed Resuscitation of Simulated Dilutional Coagulopathy in a Microfluidic Model of Bleeding When Compared to Cryoprecipitate

Impaired fibrinogen function, one component of trauma-associated coagulopathy, is highly associated with increased mortality in patients with severe traumatic bleeding. Fibrinogen replacement is crucial for improving outcomes in bleeding patients. The two most common clinically-used hemostatic adjuncts for fibrinogen supplementation are fibrinogen concentrates (FibCon) and cryoprecipitate (Cryo), yet which of these products provides better hemostatic resuscitation remains controversial. Where FibCon is predominantly a source of fibrinogen, Cryo contains additional factors which may enhance hemostatic efficacy, such as FVIII and FXIII (inherent to clot strength and fibrin crosslinking) and von Willebrand factor (VWF, important for platelet adhesion and aggregation). Cryo poses more logistical challenges than FibCon, as Cryo is a frozen product that requires thawing (20 minutes) prior to use, and has a shelf life of 4-6 hours post thaw. FibCon is lyophilized, and can be reconstituted and used within 10 minutes, but with a cost roughly 3 times that of Cryo, use of FibCon can be cost-prohibitive. Ultimately, in the setting of hemostatic resuscitation, every minute matters and each minute delay in blood product transfusion is associated with a 5% increase in mortality. Moreover, Cryo is associated with an increased risk of transfusion transmitted infection (TTI).Thus, there is a need for an immediately available and safe fibrinogen source for use in hemostatic resuscitation. Pathogen reduction (PR) of blood products renders any nucleic acid-containing source replication incompetent via crosslinking using psoralens and ultraviolet light. PR was recently adapted for use with cryoprecipitate, yielding a novel hemostatic adjunct - pathogen reduced cryoprecipitated fibrinogen complex, or PR-Cryo FC. We have previously shown PR-Cryo FC stored out to 10 days performs similarly to Cryo and FibCon in current standard assays used to assess hemostatic function. However, as primary hemostasis is dictated by physiologically relevant flow conditions, we wanted to determine if PR of cryoprecipitate altered its hemostatic function during resuscitation of dilutional coagulopathy using a microfluidic model of hemorrhage. Healthy human whole blood (WB), Cryo, FibCon, and PR-Cryo FC were stained with fluorescent antibodies specific for VWF, CD41, fibrinogen, and FXIII. Stained WB was diluted 3:7 in 0.9% NaCl to induce dilutional coagulopathy (dWB). dWB was resuscitated 1:5 with stained adjuncts (Cryo:dWB, FibCon:dWB, or PR-Cryo FC:dWB) and perfused at three different shear rates (150, 500, 3500 1/s) through a microfluidic model of hemorrhage (a lumen that "bleeds" through an injury site into a collagen/tissue factor-coated extravascular space). Occlusion of the injury site was defined as the point at which clot formation sealed the injury site for &gt; 3 minutes. The time from initial perfusion to occlusion was defined as the bleeding time (BT, seconds). If no seal was formed, the assay was stopped at 20 minutes, and the assay given a BT of 1200 seconds. Real-time phase and fluorescent images of the injury site were acquired. Data was extracted from real-time phase and fluorescent images using MATLAB. Both FibCon:dWB and PR-Cryo FC:dWB had significantly increased BT compared to Cryo:dWB at low shear (150 1/s). PR-Cryo FC:dWB had significantly increased BT compared to Cryo:dWB at medium shear (500 1/s), and at high shear (3500 1/s) there were no significant differences in BT between hemostatic adjuncts. However, kinetic analysis at high shear revealed there was a significant delay in clot formation and accumulation in the injury site, such that by 5 minutes, Cryo:dWB had filled 75% of the injury site and FibCon:dWB and PR-Cryo FC:dWB had only filled 50% of the injury site. Real-time fluorescent image analysis showed that both FibCon:dWB and PR-Cryo FC:dWB had reduced VWF deposition at the injury site compared to Cryo:dWB, and this led to a delays in platelet recruitment. FibCon has less VWF than Cryo, which would explain the delayed VWF deposition and platelet recruitment. In contrast, PR-Cryo FC and Cryo have similar amounts of VWF, suggesting that VWF from PR-Cryo FC has limited binding to the collagen-coated injury site, and as PR-Cryo FC:dWB phenocopies FibCon:dWB during clot formation at high shear, this suggests that pathogen reduction of Cryo may impair early VWF mediated capture of platelets at high shear. Disclosures Spinella: Secure Transfusion Services: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company; Cerus Corporation: Consultancy, Research Funding.

Intravenous Nanomedicine for Targeted Delivery of Thrombin to Augment Hemostasis

Non-compressible uncontrolled hemorrhage remains a major cause of mortality from traumatic injuries. Additionally, patients with congenital, disease-associated or drug-induced hemostatic dysfunctions, may often be at risk of excessive bleeding. Therefore, treatments that render rapid hemostasis are clinically significant in potentially saving lives. The clinical gold standard for this is the transfusion of whole blood (WB) or blood components (e.g. controlled ratios of platelets, RBCs, and plasma), as evidenced by several clinical studies (e.g. PROPPR, PROMMTT and PAMPer). However, the availability of such blood products is donor-dependent, their shelf-life is limited due to contamination risks, and, their portability and storage is often challenging. While extensive research efforts are currently being focused on addressing these challenges, e.g. using low titer Group O whole blood, cold-storage and freeze-drying of platelets and plasma, in vitro generation of platelets from iPSCs etc., a parallel research focus has emerged in designing biomaterials-based I.V.-administrable technologies (nanoparticles, polymers etc.) that can provide specific functional attributes of hemostasis while allowing donor-independent manufacturing, scale-up, and on-demand availability. Prominent examples of these are 'synthetic platelet' (SynthoPlate) nanoparticles that recapitulate platelet's binding interactions with von Willebrand Factor (vWF), collagen and active platelet integrin GPIIb-IIIa, flexible platelet-like particles (PLP) that bind fibrin to recapitulate platelet's biomechanical properties, fibrinogen function-mimicking nanoparticles that amplify the aggregation of active platelets, peptide-modified synthetic polymers (e.g. PolySTAT, HAPPI etc.) that render clot stabilization etc. In this framework, we present the design and evaluation of I.V.-administrable unique platelet-inspired nanoparticles that render injury site-targeted, enzyme-responsive direct delivery of thrombin, to site-specifically augment fibrin generation for hemostasis. Our design is inspired by platelets' crucial hemostatic mechanisms of : (i) rapidly accumulating at the injury site to form a plug and (ii) serving as a coagulation amplifier via presenting anionic phospholipids on the activated platelet surface to render tenase and prothrombinase factor assemblies leading to thrombin (FIIa) burst, which can then site-specifically convert fibrinogen to fibrin. Thrombin delivery to augment hemostasis is clinically well-accepted, as exemplified by products like Tisseel where thrombin and fibrinogen are co-delivered by syringe directly at wound site. Researchers have also studied thrombin-loaded topical dressings and topical administration of thrombin-loaded particles on wounds to mitigate bleeding, but these cannot be used intravenously. A recent interesting study has explored encapsulation of thrombin-loaded nanoparticles inside actual platelets with the idea of the particles being released (analogous to granule secretion) upon platelet activation, but this was only demonstrated in vitro because optimizing this complex strategy for consistent in vivo function may be challenging. Our approach circumvents these challenges by: (i) loading consistent amount of thrombin in I.V.-administrable lipid nanoparticles (LNPs), (ii) directly targeting the thrombin-loaded LNPs (TLNPs) to the injury site via specific binding to vWF and collagen, and (iii) releasing the loaded thrombin via particle destabilization by the action of injury site-specific enzyme phospholipase A2 for in situ fibrin production. We evaluated the TLNPs in vitro in human blood and plasma where hemostatic defects were created by platelet depletion and anticoagulant treatment. Spectrophotometric studies of fibrin generation, rotational thromboelastometry (ROTEM) based studies of clot characteristics and BioFlux microfluidics based real-time imaging of fibrin generation under simulated vascular flow conditions, confirmed the ability of TLNPs to restore fibrin generation in hemostatic dysfunction settings. Subsequently, the in vivo feasibility of these TLNPs was tested in a mouse tail-clip bleeding model where a combination of platelet depletion plus anticoagulant treatment was used to render significant hemostatic defect. TLNPs were able to effectively reduce tail-bleeding in mice. Figure 1 Figure 1. Disclosures Sen Gupta: Haima Therapeutics: Other: Co-founder, Patents & Royalties: US 9107845, US 9107963.

Injury-induced inflammatory signaling and hematopoiesis in Drosophila

Inflammatory response in Drosophila to sterile (axenic) injury in embryos and adults has received some attention in recent years, and most concentrate on the events at the injury site. Here we focus on the effect sterile injury has on the hematopoietic organ, the lymph gland, and the circulating blood cells in the larva, the developmental stage at which major events of hematopoiesis are evident. In mammals, injury activates Toll-like receptor (TLR)/NFκB signaling in macrophages, which then express and secrete secondary, pro-inflammatory cytokines. In Drosophila larvae, distal puncture injury of the body wall epidermis causes a rapid activation of Toll and Jun kinase (JNK) signaling throughout the hematopoietic system and the differentiation of a unique blood cell type, the lamellocyte. Furthermore, we find that Toll and JNK signaling are coupled in their activation. Secondary to this Toll/JNK response, a cytokine, Upd3, is induced as a Toll pathway transcriptional target, which then promotes JAK/STAT signaling within the blood cells. Toll and JAK/STAT signaling are required for the emergence of the injury-induced lamellocytes. This is akin to the derivation of specialized macrophages in mammalian systems. Upstream, at the injury site, a Duox- and peroxide-dependent signal causes the activation of the proteases Grass and SPE needed for the activation of the Toll-ligand Spz, but microbial sensors or the proteases most closely associated with them during septic injury are not involved in the axenic inflammatory response.

Epidemiology of Maxillofacial Injuries in “Heratsi” No 1 University Hospital in Yerevan, Armenia: A Retrospective Study

Background: The aim of this study was to perform a retrospective analysis of the prevalence, etiologies, and types of maxillofacial injuries (MFI) and sites of maxillofacial fractures (MFF) and their management in Yerevan, Armenia.Methods: A retrospective cross-sectional study was conducted. Data including age, sex, date of referral, mode of injury, etiology, radiology records and treatment methods were extracted. Study outcomes were measured using percentages, means, standard deviations and tests of proportions. P <.05 was considered significant.Results: A total of 204 patients had a mean age of 36.26 ±1.08 years (156 males and 48 females), and a total of 259 MFIs were recorded between 2017 and 2020. Interpersonal violence (IV) was found to be the most common etiology of MFFs in this study (42.1%), followed by road traffic accidents (RTAs) (27.9%) and falls (18.6%). The nasal bone was the most common injury site (47.5%), followed by the mandible (31.4%) and zygomatic complex (11.7%). The most common fracture site was the mandibular angle (37.9%), followed by the symphysis/parasymphysis (28.1%) and body (12.6%). The majority of MFFs were treated by open reduction and internal fixation.Conclusion: Interpersonal violence, followed by RTAs and falls, was the most common cause of MFIs. The nasal bone was the most common injury site, followed by the mandible and zygomatic complex. Social education with the objective of reducing aggression and interpersonal conflict should be improved, and appropriate RTA prevention strategies should be strengthened and implemented.