Bioresorbable Film for the Prevention of Adhesion to the Anterior Spine After Anterolateral Discectomy

Background context The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions. Purpose To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy. Study design Experimental study. Methods Seven, skeletally mature female sheep underwent a retroperitoneal approach to the anterolateral lumbar spine. A discectomy was performed at two levels with an intervening unoperated disc site. One site was treated with a polylactide film barrier (Hydrosorb Shield; MacroPore Biosurgery, San Diego, CA) affixed with tacks manufactured from the same material. The second site was left untreated. Treatment and control sites were randomly assigned. Postmortem analysis included scar tenacity scoring on five spines and histological evaluation on two spines. Results The application of the Hydrosorb film barrier allowed a definite dissection plane during scar tenacity scoring and there was a significant difference in the development of adhesions to the disc between the control and treated sites. Histological evaluation revealed evidence of barrier formation to scar tissue and no significant adverse inflammatory reactions. Conclusions Hydrosorb Shield appears to be an effective postoperative barrier to scar tissue adhesion after anterolateral discectomy. The use of polylactide tacks was beneficial to affix the barrier film in place. Safety issues associated with delayed healing or adverse response to the film or tacks were not observed. Hydrosorb film may be useful as an antiadhesion barrier facilitating dissection during surgical revision in anterior approaches to the spine. Further studies are indicated to evaluate the performance of the bioresorbable material as an antiadhesion barrier in techniques of spinal fusion and disc replacement

Leucine Zipper-Bearing Kinase Is a Critical Regulator of Astrocyte Reactivity in the Adult Mammalian CNS.

Reactive astrocytes influence post-injury recovery, repair, and pathogenesis of the mammalian CNS. Much of the regulation of astrocyte reactivity, however, remains to be understood. Using genetic loss and gain-of-function analyses in vivo, we show that the conserved MAP3K13 (also known as leucine zipper-bearing kinase [LZK]) promotes astrocyte reactivity and glial scar formation after CNS injury. Inducible LZK gene deletion in astrocytes of adult mice reduced astrogliosis and impaired glial scar formation, resulting in increased lesion size after spinal cord injury. Conversely, LZK overexpression in astrocytes enhanced astrogliosis and reduced lesion size. Remarkably, in the absence of injury, LZK overexpression alone induced widespread astrogliosis in the CNS and upregulated astrogliosis activators pSTAT3 and SOX9. The identification of LZK as a critical cell-intrinsic regulator of astrocyte reactivity expands our understanding of the multicellular response to CNS injury and disease, with broad translational implications for neural repair

The study of glial scar formation after brain ischemia using in-vitro strategies

Reactive gliosis is a generic response to Central Nervous System (CNS) injury mediated by astrocytes and microglia. Following ischemic damage to the CNS parenchyma, the injured area becomes surrounded by a dense astroglial cell layer known as glial scar. Glial scar formation has been recognized for many decades as a major impediment for neuronal reconnection and a serious obstacle for functional recovery. However, more recent studies have shown that scar limits the area of damage, preventing the diffusion of blood-derived activated immune cells into the CNS that could cause a generalized proinflammatory-neurodegenerative response.\nIn spite that it has been morphologically recognized for many years since Ramon y Cajal times, to study the biochemical signaling cascades involved in glial scar formation has been difficult mostly because of the in vivo nature of the process.\nIn this context, we studied here the mechanisms of glial scar assembly/disassembly in vitro to identify potential pharmacological targets for therapeutic interventions. To achieve this goal we will use the classical 2-Dimensional (2D) astroglial cultures, but we will also develop 3-dimensional (3D) astroglial cultures by using nanotube matrixes to attempt to better reproduce the in vivo situation. The results of this thesis showed that meningeal macrophages or ischemia-activated macrophages induce astroglial retraction and formation of scar-like structures in vitro. Scar-forming astrocytes over-express GFAP, S100B and TLR2-4. Using the NF-?B antagonist BAY-11-7082 we demonstrated that scar formation and its density is partially NF-?B dependent. Finally, in 3D astroglial culture grown on hydromatrix nanotubes, we showed that DAMPs can induce astroglial polarization but not the formation of the glial scar in vitro. We conclude that TLR/ NF-?B pathway is probably implicated in the glial scar formation or stabilization and that DAMPs and macrophages are necessary for the formation of glial scars in vitro.Fil: Mannava, Raja Sekhar. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin

Tissue Stromal Vascular Fraction Improves Early Scar Healing:A Prospective Randomized Multicenter Clinical Trial

Background Wound healing and scar formation depends on a plethora of factors. Given the impact of abnormal scar formation, interventions aimed to improve scar formation would be most advantageous. The tissue stromal vascular fraction (tSVF) of adipose tissue is composed of a heterogenous mixture of cells embedded in extracellular matrix. It contains growth factors and cytokines involved in wound-healing processes, eg, parenchymal proliferation, inflammation, angiogenesis, and matrix remodeling.Objectives The aim of this study was to investigate the hypothesis that tSVF reduces postsurgical scar formation.Methods This prospective, double-blind, placebo-controlled, randomized trial was conducted between 2016 and 2020. Forty mammoplasty patients were enrolled and followed for 1 year. At the end of the mammoplasty procedure, all patients received tSVF in the lateral 5 cm of the horizontal scar of 1 breast and a placebo injection in the contralateral breast to serve as an intrapatient control. Primary outcome was scar quality measure by the Patient and Observer Scar Assessment Scale (POSAS). Secondary outcomes were obtained from photographic evaluation and histologic analysis of scar tissue samples.Results Thirty-four of 40 patients completed follow-up. At 6 months postoperation, injection of tSVF had significantly improved postoperative scar appearance as assessed by the POSAS questionnaire. No difference was observed at 12 months postoperation. No improvement was seen based on the evaluation of photographs and histologic analysis of postoperative scars between both groups.Conclusions Injection of tSVF resulted in improved wound healing and reduced scar formation at 6 months postoperation, without any noticeable advantageous effects seen at 12 months.</p

Prevalence of BCG scar among BCG-vaccinated children in a southern Nigeria tertiary hospital

Background: The burden of tuberculosis is high in Nigeria as in other developing countries. The administration of BCG vaccine to neonates is essential in the control of tuberculosis. A scar usually develops 6 – 8 weeks later at the site of vaccination, which can be used clinically as a proof ofvaccination. Not all vaccinated infants however, develop a BCG scar.Objectives: To determine the prevalence of scar formation postvaccinationand to unravel, if present, any factors responsible for scar failure.Methods: Two hundred and fourteen children were consecutively recruited from those who presented for immunization in the University of Benin Teaching Hospital, Benin. The bio-data and other relevant information were obtained using a proforma. The anthropometric measurements of the children were obtained and the children were examined for presence of a BCG scar.Results: Two hundred and six subjects (96.3%) had a postvaccination BCG scar. About 72% of the subjects were vaccinated within the first week of life. The age at vaccination was significantly affected by gestational maturation (P=0.003) and birth weight (P=0.0001). Gestational maturation is a strong predictor of BCG scar formation postvaccination (P = 0.007)Conclusion: There is high prevalence of BCG scar formation in this study and gestational maturation is a strong predictor of BCG scar formation

PLG Bridge Implantation in Chronic SCI Promotes Axonal Elongation and Myelination.

Spinal cord injury (SCI) is a devastating condition that may cause permanent functional loss below the level of injury, including paralysis and loss of bladder, bowel, and sexual function. Patients are rarely treated immediately, and this delay is associated with tissue loss and scar formation that can make regeneration at chronic time points more challenging. Herein, we investigated regeneration using a poly(lactide-co-glycolide) multichannel bridge implanted into a chronic SCI following surgical resection of necrotic tissue. We characterized the dynamic injury response and noted that scar formation decreased at 4 and 8 weeks postinjury (wpi), yet macrophage infiltration increased between 4 and 8 wpi. Subsequently, the scar tissue was resected and bridges were implanted at 4 and 8 wpi. We observed robust axon growth into the bridge and remyelination at 6 months after initial injury. Axon densities were increased for 8 week bridge implantation relative to 4 week bridge implantation, whereas greater myelination, particularly by Schwann cells, was observed with 4 week bridge implantation. The process of bridge implantation did not significantly decrease the postinjury function. Collectively, this chronic model follows the pathophysiology of human SCI, and bridge implantation allows for clear demarcation of the regenerated tissue. These data demonstrate that bridge implantation into chronic SCI supports regeneration and provides a platform to investigate strategies to buttress and expand regeneration of neural tissue at chronic time points

Surgical Treatment of Burn Scars

The relationship between a burns patient and a reconstructive surgeon is normally long lasting and continues lifelong. Patients not only require a surgeon’s professional expertise, but also time, optimism and compassion. Scar management relates to the physical and aesthetic components as well as the psychosocial implications of scarring. Hypertrophic scar formation which can cause debilitating deficiencies and poor aesthetic outcomes might be a result of burn injuries. Although nonsurgical treatment modalities in the early phase of scar maturation are critical to decrease hypertrophic scar formation, surgical management is often indicated to restore function. Operative scar management releases the tension and can often be achieved through local tissue arrangement

AKAP12 Mediates Barrier Functions of Fibrotic Scars during CNS Repair

The repair process after CNS injury shows a well-organized cascade of three distinct stages: inflammation, new tissue formation, and remodeling. In the new tissue formation stage, various cells migrate and form the fibrotic scar surrounding the lesion site. The fibrotic scar is known as an obstacle for axonal regeneration in the remodeling stage. However, the role of the fibrotic scar in the new tissue formation stage remains largely unknown. We found that the number of A-kinase anchoring protein 12 (AKAP12)-positive cells in the fibrotic scar was increased over time, and the cells formed a structure which traps various immune cells. Furthermore, the AKAP12-positive cells strongly express junction proteins which enable the structure to function as a physical barrier. In in vivo validation, AKAP12 knock-out (KO) mice showed leakage from a lesion, resulting from an impaired structure with the loss of the junction complex. Consistently, focal brain injury in the AKAP12 KO mice led to extended inflammation and more severe tissue damage compared to the wild type (WT) mice. Accordingly, our results suggest that AKAP12-positive cells in the fibrotic scar may restrict excessive inflammation, demonstrating certain mechanisms that could underlie the beneficial actions of the fibrotic scar in the new tissue formation stage during the CNS repair process

Molecular requirements for actin-based lamella formation in Drosophila S2 cells

Cell migration occurs through the protrusion of the actin-enriched lamella. Here, we investigated the effects of RNAi depletion of ∼90 proteins implicated in actin function on lamella formation in Drosophila S2 cells. Similar to in vitro reconstitution studies of actin-based Listeria movement, we find that lamellae formation requires a relatively small set of proteins that participate in actin nucleation (Arp2/3 and SCAR), barbed end capping (capping protein), filament depolymerization (cofilin and Aip1), and actin monomer binding (profilin and cyclase-associated protein). Lamellae are initiated by parallel and partially redundant signaling pathways involving Rac GTPases and the adaptor protein Nck, which stimulate SCAR, an Arp2/3 activator. We also show that RNAi of three proteins (kette, Abi, and Sra-1) known to copurify with and inhibit SCAR in vitro leads to SCAR degradation, revealing a novel function of this protein complex in SCAR stability. Our results have identified an essential set of proteins involved in actin dynamics during lamella formation in Drosophila S2 cells

Topical Application of an Irreversible Small Molecule Inhibitor of Lysyl Oxidases Ameliorates Skin Scarring and Fibrosis

Scarring is a lifelong consequence of skin injury, with scar stiffness and poor appearance presenting physical and psychological barriers to a return to normal life. Lysyl oxidases are a family of enzymes that play a critical role in scar formation and maintenance. Lysyl oxidases stabilize the main component of scar tissue, collagen, and drive scar stiffness and appearance. Here we describe the development and characterisation of an irreversible lysyl oxidase inhibitor, PXS-6302. PXS-6302 is ideally suited for skin treatment, readily penetrating the skin when applied as a cream and abolishing lysyl oxidase activity. In murine models of injury and fibrosis, topical application reduces collagen deposition and cross-linking. Topical application of PXS-6302 after injury also significantly improves scar appearance without reducing tissue strength in porcine injury models. PXS-6302 therefore represents a promising therapeutic to ameliorate scar formation, with potentially broader applications in other fibrotic diseases