Scar Region Research Articles

Research on the synergistic damage behavior of tribocorrosion of CoCrFeNi-X (Ti, Mn, Mo, Al) high-entropy alloys

This study investigates the damage behavior of CoCrFeNi-X (Ti, Mn, Mo, Al) high-entropy alloy coatings under reciprocating friction in a 3.5 wt% NaCl solution. Conventional tribocorrosion experiments and full-contact tribocorrosion tests were conducted to analyze the synergistic effects of corrosion and wear. Electrochemical analysis and surface characterization of the worn samples were performed to quantify the losses resulting from the synergistic effects in tribocorrosion. The results demonstrate a significant increase in the corrosion rate in the worn area by 2–3 orders of magnitude due to friction, accompanied by a notable potential difference between the wear scar region and the surrounding area. While corrosion products can reduce the friction coefficient, the localized damage induced by corrosion significantly enhances the wear volume.

Matricellular protein CCN1 promotes collagen alignment and scar integrity after myocardial infarction

BackgroundMembers of the cellular communication network family (CCN) of matricellular proteins, like CCN1, have long been implicated in the regulation of cellular processes underlying wound healing, tissue fibrogenesis, and collagen dynamics. While many studies suggest antifibrotic actions for CCN1 in the adult heart through the promotion of myofibroblast senescence, they largely relied on exogenous supplementation strategies in in vivo models of cardiac injury where its expression is already induced—which may confound interpretation of its function in this process. The objective of this study was to interrogate the role of the endogenous protein on fibroblast function, collagen structural dynamics, and its associated impact on cardiac fibrosis after myocardial infarction (MI). Methods/resultsHere, we employed CCN1 loss-of-function methodologies, including both in vitro siRNA-mediated depletion and in vivo fibroblast-specific knockout mice to assess the role of the endogenous protein on cardiac fibroblast fibrotic signaling, and its involvement in acute scar formation after MI. In vitro depletion of CCN1 reduced cardiac fibroblast senescence and proliferation. Although depletion of CCN1 decreased the expression of collagen processing and stabilization enzymes (i.e., P4HA1, PLOD1, and PLOD2), it did not inhibit myofibroblast induction or type I collagen synthesis. Alone, fibroblast-specific removal of CCN1 did not negatively impact ventricular performance or myocardial collagen content but did contribute to disorganization of collagen fibrils and increased matrix compliance. Similarly, Ccn1 ablated animals subjected to MI showed no discernible alterations in cardiac structure or function one week after permanent coronary artery ligation, but exhibited marked increases in incidence of mortality and cardiac rupture. Consistent with our findings that CCN1 depletion does not assuage myofibroblast conversion or type I collagen synthesis in vitro, Ccn1 knockout animals revealed no measurable differences in collagen scar width or mass compared to controls; however, detailed structural analyses via SHG and TEM of scar regions revealed marked alterations in their scar collagen topography—exhibiting changes in numerous macro- and micro-level collagen architectural attributes. Specifically, Ccn1 knockout mice displayed heightened ECM structural complexity in post-MI scar regions, including diminished local alignment and heightened tortuosity of collagen fibers, as well as reduced organizational coherency, packing, and size of collagen fibrils. Associated with these changes in ECM topography with the loss of CCN1 were reductions in fibroblast-matrix interactions, as evidenced by reduced fibroblast nuclear and cellular deformation in vivo and reduced focal-adhesion formation in vitro; findings that ultimately suggest CCN1’s ability to influence fibroblast-led collagen alignment may in part be credited to its capacity to augment fibroblast-matrix interactions. ConclusionsThese findings underscore the pivotal role of endogenous CCN1 in the scar formation process occurring after MI, directing the appropriate arrangement of the extracellular matrix's collagenous components in the maturing scar—shaping the mechanical properties that support its structural stability. While this suggests an adaptive role for CCN1 in regulating collagen structural attributes crucial for supporting scar integrity post MI, the long-term protracted expression of CCN1 holds maladaptive implications, potentially diminishing collagen structural complexity and compliance in non-infarct regions.

A retrospective study of predisposing factors and management of incisional hernia in a tertiary care hospital

Background: An incisional hernia is characterized as any defect in the abdominal wall, with or without a noticeable bulge, in the region of a postoperative scar, identifiable through clinical examination or imaging. This condition can be detected through clinical examination or imaging and affects approximately 10-20% of patients who undergo abdominal operations. Aims and objectives of the study was to evaluate various precipitating factors, clinical presentations, management and post-operative complications in patients with incisional hernia. Methods: A retrospective study of 150 patients conducted at a tertiary care teaching hospital. Results: In this study, incisional hernia was more common in obese, elderly, and female patients. The incidence was higher with Pfannenstiel incision followed by lower midline incisions. Incisional hernia was common between 1-5 years of index surgery and it was observed that more the risk factors and complications associated with index surgery, earlier was the onset of incisional hernia. Patients had a defect of size <4x4 cm were 58.66%. Open onlay mesh repair was done in 36.66% patients, preperitoneal mesh repair in 13.33%, retro rectus mesh repair in 13.33%, laparoscopic mesh repair in 28.66% and anatomical repair alone in 7.99% patients. Duration of laparoscopic surgery was longer compared to open. Most common post- operative complication was seroma (4.66%) followed by wound infection (2.66%). Conclusions: Incisional hernias occur more in females as they commonly undergo lower abdominal surgeries. Subcutaneous suction drain decreased the incidence of post-operative wound complications.

Heterogeneous fibroblasts contribute to fibrotic scar formation after spinal cord injury in mice and monkeys

Spinal cord injury (SCI) leads to fibrotic scar formation at the lesion site, yet the heterogeneity of fibrotic scar remains elusive. Here we show the heterogeneity in distribution, origin, and function of fibroblasts within fibrotic scars after SCI in mice and female monkeys. Utilizing lineage tracing and single-cell RNA sequencing (scRNA-seq), we found that perivascular fibroblasts (PFs), and meningeal fibroblasts (MFs), rather than pericytes/vascular smooth cells (vSMCs), primarily contribute to fibrotic scar in both transection and crush SCI. Crabp2 + /Emb+ fibroblasts (CE-F) derived from meninges primarily localize in the central region of fibrotic scars, demonstrating enhanced cholesterol synthesis and secretion of type I collagen and fibronectin. In contrast, perivascular/pial Lama1 + /Lama2+ fibroblasts (LA-F) are predominantly found at the periphery of the lesion, expressing laminin and type IV collagen and functionally involved in angiogenesis and lipid transport. These findings may provide a comprehensive understanding for remodeling heterogeneous fibrotic scars after SCI.

Antiarrhythmic Mechanisms of Epidural Blockade After Myocardial Infarction.

Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachycardia in small case series of patients with refractory ventricular tachyarrhythmias and cardiomyopathy. However, its electrophysiological and autonomic effects in diseased hearts remain unclear, and its use after myocardial infarction is limited by concerns for potential right ventricular dysfunction. Myocardial infarction was created in Yorkshire pigs (N=22) by left anterior descending coronary artery occlusion. Approximately, six weeks after myocardial infarction, an epidural catheter was placed at the C7-T1 vertebral level for injection of 2% lidocaine. Right and left ventricular hemodynamics were recorded using Millar pressure-conductance catheters, and ventricular activation recovery intervals (ARIs), a surrogate of action potential durations, by a 56-electrode sock and 64-electrode basket catheter. Hemodynamics and ARIs, baroreflex sensitivity and intrinsic cardiac neural activity, and ventricular effective refractory periods and slope of restitution (Smax) were assessed before and after TEA. Ventricular tachyarrhythmia inducibility was assessed by programmed electrical stimulation. TEA reduced inducibility of ventricular tachyarrhythmias by 70%. TEA did not affect right ventricular-systolic pressure or contractility, although left ventricular-systolic pressure and contractility decreased modestly. Global and regional ventricular ARIs increased, including in scar and border zone regions post-TEA. TEA reduced ARI dispersion specifically in border zone regions. Ventricular effective refractory periods prolonged significantly at critical sites of arrhythmogenesis, and Smax was reduced. Interestingly, TEA significantly improved cardiac vagal function, as measured by both baroreflex sensitivity and intrinsic cardiac neural activity. TEA does not compromise right ventricular function in infarcted hearts. Its antiarrhythmic mechanisms are mediated by increases in ventricular effective refractory period and ARIs, decreases in Smax, and reductions in border zone electrophysiological heterogeneities. TEA improves parasympathetic function, which may independently underlie some of its observed antiarrhythmic mechanisms. This study provides novel insights into the antiarrhythmic mechanisms of TEA while highlighting its applicability to the clinical setting.

A Comparative Study in Elective Repair of Large Incisional Hernias Using On-Lay Mesh vs. Sub-Lay Mesh – A Meta-Analysis

Abstract Background Ventral abdominal wall incisional hernia is defined as a defect in the musculo-fascial layers of the abdominal wall in the region of postoperative scar. There is a slight increase in the incidence of incisional hernia in the female gender. The higher percentage of incisional hernia in females might be due to laxity of abdominal wall muscles after multiple pregnancies and also increased incidence of obesity in females. Objective To assess incisional hernia repair using two different techniques: on-lay mesh and sub- lay mesh, as regards operative time, postoperative recurrence, wound infection, seroma, hematoma and flap necrosis. Patients and Methods The Pubmed, web of science and Scopus were searched on 15 March, 2022. The keywords incisional hernia, sub-lay mesh on-lay mesh, retromuscular mesh, polypropylene. Results and Conclusion According to our results, there is a statistical difference between onlay and sublay regarding intra-operative time as sublay mesh is more time consuming. Regarding post- operative complications there is no statistical difference in recurrence, seroma, hematoma, flap necrosis and infection but there is a statistical difference regarding in hospital stay as patients with sublay repair stays less than onlay.

Integrated Single-Cell Analysis Reveals Spatially and Temporally Dynamic Heterogeneity in Fibroblast States during Wound Healing

Wound healing is a dynamic process over temporal and spatial scales. Key to repair outcomes are fibroblasts, yet how they modulate healing across time and in different wound regions remains incompletely understood. By integrating single-cell RNA-sequencing datasets of mouse skin and wounds, we infer that fibroblasts are the most transcriptionally dynamic skin-resident cells, evolving during postnatal skin maturation, and rapidly after injury towards distinct late scar states. We show that transcriptional dynamics in fibroblasts are largely driven by genes encoding extracellular matrix and signaling factors. Lineage trajectory inference and spatial gene mapping reveal that Prg4-expressing fibroblasts transiently emerge along early wound edges. Within days, they become replaced by long-lasting and likely non-interconverting fibroblast populations, including Col25a1-expressing and Pamr1-expressing fibroblasts that occupy subepidermal and deep scar regions, respectively, where they engage in reciprocal signaling with immune cells. Signaling inference shows that fibroblast-immune crosstalk repeatedly uses some signaling pathways across wound healing time, while use of other signaling pathways is time- and space-limited. Collectively, we uncovered high transcriptional plasticity by wound fibroblasts, with early states transiently forming distinct micro-niches along wound edges and in the fascia, followed by stable states, that stratify scar tissue into molecularly dissimilar upper and lower layers.

ENDOSCOPIC DRAINAGE FOR THE MANAGEMENT OF INFECTED SUBCUTANEOUS COLLECTIONS FOLLOWING DIEP FLAP RECONSTRUCTION TECHNIQUE: A CASE REPORT

Abstract Aim The deep inferior epigastric perforator (DIEP) flap procedure is a widely accepted method for immediate breast reconstruction following skin-sparing mastectomy in breast cancer patients. While complications are infrequent, challenges may arise, including surgical wound infection, skin necrosis, seroma, or hematoma. Methods We present the case of a 68-year-old woman with multifocal infiltrating carcinoma of the right breast (T1cN0M0) who underwent DIEP flap breast reconstruction one month before presenting to the emergency room. Her symptoms included a fever of 38°C, abdominal filling in the DIEP scar region, an elevated leukocyte count (23.01 × 10E3/microL), and a C-reactive protein level of 470 mg/L. Abdominal CT revealed a collection in the infraumbilical anterior abdominal wall extending through the subcutaneous cellular tissue of both iliac fossae. The patient underwent surgical intervention, including endoscopic drainage with lavage and drain placement under direct visualization. Results Following surgery, the patient responded positively to intravenous Meropenem, with the resolution of fever and improvement in local cellulitis. She was discharged on the 6th postoperative day with both drains, removed 10 and 15 days after surgery in an outpatient setting. Conclusions In cases where immediate percutaneous drainage is not feasible, endoscopic drainage emerges as an effective strategy for managing extensive infectious collections. This technique, involving lavage, debridement, and drain placement under direct vision, eliminates the need to reopen substantial surgical wounds. Notably, this approach aids early recovery in patients undergoing active chemotherapy, preventing delays in chemotherapy administration.

Single-beat mapping during programmed ventricular stimulation identifies infarct-related ventricular tachycardia isthmus sites

Abstract Introduction Complete characterization of reentrant ventricular tachycardia (VT) circuits using classical electrophysiological criteria and high-density mapping during VT is complex. Often, VT episodes cannot be fully characterized because of hemodynamic instability during the mapping procedure. This common limitation has motivated the implementation of mapping strategies during sinus rhythm or ventricular pacing aiming to identify scar regions associated with VT isthmuses or potential arrhythmogenicity. However, these strategies still require time-consuming catheter-based mapping. Purpose We aimed to develop and validate a single-beat mapping strategy during programmed ventricular stimulation (PVS) to identify scar regions associated with VT isthmus sites. We hypothesize that protected VT isthmuses within scar regions are characterized by larger activation time dispersion than surrounding scar areas not related to critical isthmus sites. Methods Experimental study including 16 pigs with established myocardial infarction (MI) in the anterior wall. Ten-to-twelve weeks after MI, pigs underwent left ventricular characterization using 3D late-gadolinium enhancement cardiac magnetic resonance imaging, and further invasive electroanatomical mapping to obtain high-density sequential activation maps during ventricular pacing and VT. High-density maps were compared with single-beat maps using a 64-pole basket catheter positioned in the left ventricle. After VT induction, high-density activation maps in well-tolerated VT episodes were used to identify VT isthmus sites. Simultaneous activation data from the 64-pole basket catheter were also obtained during PVS and VT. Off-line analysis was performed to: (i) validate single-beat activation maps during the baseline drive pacing cycle length (S1), and (ii) identify basket-catheter electrodes with the larger local activation time-dispersion score (LAT-DS) during PVS including up to 4 coupled extrastimuli (S2, S3, S4, S5) (Figure 1). LAT-DS was defined as the normalized product of the LAT of each electrode and the activation dispersion among its neighboring electrodes. Results Basket-catheter based single-beat activation maps during S1 pacing showed high correlation values with high-density sequential activation maps (N=16. R²=0.91). In 7 pigs, the VT isthmus site was fully characterized using high-density activation maps. During any of the coupled extrastimuli of the PVS protocol, basket catheter electrodes colocalizing with documented VT isthmus sites on high-density maps showed higher LAT-DS values compared to surrounding electrodes located on scar or healthy regions. Conversely, LAT values alone could not differentiate scar regions relevant for VT maintenance during PVS protocol (Figure 2). Conclusions Sixty-four pole single-beat activation maps during PVS identify left ventricular scar areas with higher than surrounding LAT-DS values that are associated with VT isthmus sites.Figure 1.Experimental modelFigure 2.A-Example. B-C-Full results

Computed tomography as a predictive tool for ventricular tachycardia

Abstract Background Sudden cardiac death is the main cause of mortality worldwide. It is often linked with ventricular tachycardia (VT). To prevent VT, high-risk patients are typically equipped with intracardiac defibrillators (ICDs). Currently, left ventricular ejection fraction (LVEF) is the standard for determining a patient's risk level. Objective We hypothesized that the use of imaging software analyzing cardiac CT-scans could enhance the detection of patients with an increased risk of VT. Methods and Results In this study, 132 patients with ischemic cardiomyopathy (average age 66.2±11.4 years, with an average LVEF of 36.6±10.3%), all with implanted cardiac devices, underwent CT scans. We developed software to automatically analyze the heart's wall tissue thickness, cardiac fat, and calcification levels (Figure.1.A). A viable cardiac wall thickness of less than 3mm typically indicates a ventricular wall predominantly composed of scar tissue with minimal viable tissue remaining. In contrast, a viable wall thickness of less than 5mm includes regions with more viable tissue and therfore represents the total scar. Over an average follow-up of 6.6 years (79.8 ± 30.5 months) via live telemedicine, we observed that patients with VT had a significant difference in wall thickness ratio (3mm/5mm; no VT 0.31±0.18 vs, VT 0.44±0.18, p<0.01)) and higher calcification (0.10±0.38ml vs. 0.47±1.57ml, p=0.039). The amount of cardiac fat did not significantly differ between the no VT and VT groups (1.14±1.38ml vs.1.21±1.01ml, p=0.771). Logistic regression determined a critical cutoff for wall thickness at a ratio of 0.3 for 3mm and 5mm thickness. Kaplan Meyer analysis contrasted this wall thickness ratio of 0.3 (figure.1.B) against the established LVEF threshold of 35% (figure.1.C) for predicting VT-free survival, revealing a notable disparity favoring wall thickness ratio (p<0.01) over LVEF (p=0.77). Conclusions The findings suggest that a higher proportion of regions of thin viable tissue or dense scar in the total scar is a more effective predictor of VT-free survival than LVEF, potentially improving the identification of patients at risk for sudden cardiac death.Figure. 1

Novel systematic processing of cardiac magnetic resonance imaging identifies target regions associated with infarct-related ventricular tachycardia

Abstract Introduction In the clinic, complete characterization of reentrant ventricular tachycardia (VT) circuits using classical electrophysiological criteria and state-of-the-art high density mapping during VT is complex, and often cannot be completed because of hemodynamic instability. This common limitation has motivated the implementation of mapping strategies during sinus rhythm or ventricular pacing aiming to identify scar regions associated with VT isthmuses or potential arrhythmogenicity. Complementary imaging-based strategies including advanced analyses of scar tissue characteristics have been also proposed for procedure planning and identification of potential arrhythmogenic regions. However, the most recent expert consensus report on catheter ablation of ventricular arrhythmia highlights the lack of agreement on the preferable signal intensity (SI) cut-off values for assessment of tissue heterogeneity and scar areas on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) images. The latter makes LGE-CMR imaging processing highly operator-dependent and potentially sensitive to selection bias. Purpose We aimed at developing and validating a systematic processing approach on LGE-CMR images to identify potential VT corridors that may include protected isthmuses associated with VT maintenance. Methods Translational study including 18 pigs with established myocardial infarction and inducible VT undergoing in vivo characterization of the anatomical and functional myocardial substrate associated with VT maintenance. Clinical validation was conducted in a multicenter series of 33 patients with ischemic cardiomyopathy undergoing VT ablation. Three-dimensional CMR-LGE images were processed using systematic scanning of 15 signal intensity cut-off ranges to obtain surface visualization of all potential VT corridors. Analysis and comparisons of imaging and electrophysiological data were performed in individuals with full electrophysiological characterization of the isthmus sites of at least one VT morphology. Results In both the experimental pig model and patients undergoing VT ablation, all the electrophysiologically-defined isthmus sites (n=11 and n=19, respectively) showed overlapping regions with CMR-based potential VT corridors. Such imaging-based VT corridors were less specific than electrophysiologically-guided ablation lesions at functionally relevant isthmus sites (Figure). However, in patients, decreasing from 15 to 7 the number of signal intensity cut-off ranges for systematic imaging processing significantly reduced the area of imaging-based potential VT corridors, without diminishing the capability to detect functionally relevant VT isthmus sites. Conclusions Systematic processing of 3D LGE-CMR images provides unbiased identification of imaging based potential VT corridors that contain functionally relevant protected isthmus sites.

Exploration of peak frequency mapping for ventricular tachycardia ablation. Identification of critical isthmus zones during substrate mapping

Abstract Background/Introduction The ability to classify and differentiate between near field and far-field components of intracardiac signals is a key element in identifying critical arrhythmogenic substrate during ventricular tachycardia (VT) ablation. Near Field algorithms based on omnipolar electrograms enable detection and automation of true localised signals providing unique insights into substrate characteristics. This novel feature identifies localised signal peak frequency (PF) which can be displayed across different voltage ranges. Purpose/Aims The significance of PF mapping in the context of VT ablation is limited and its utility in the identification of the critical diastolic isthmus zone (IZ) is not known. The aim of this study is to explore the utilisation of PF mapping during VT ablation and evaluate whether significant differences in PF occur within areas of interest and critical components of the VT circuit during substrate mapping. Methods All patients underwent VT ablation using the EnSite™ X mapping system with the HDGrid omnipolar mapping catheter. Only cases with both high density sinus rhythm (SR) substrate maps and VT activation maps with clear identification of the IZ were included. VT activation and propagation maps were generated and the diastolic IZ was superimposed onto the SR substrate map. PF analysis was performed retrospectively. Surface area, omnipolar voltage and PF of the maps were measured in the SR substrate maps and co-localised with the critical IZ of the VT circuit as identified in the VT activation maps. Analysis of PF was conducted across different voltage ranges: healthy myocardium (>1.5mV), scar (1.5-0.5mV) and dense scar (0.5-0.1mV). Sensitivity and specificity measurements were made within segments of the IZ and non-isthmus zones and depicted as ROC curves. Results 55 patients underwent VT ablation over a 12-month period, with a total of 18 fulfilling the inclusion criteria. Mean age was 70 (±12.5years) with an average ejection fraction of 36%. The overall PF of the SR substrate maps was 121.85±26.85 Hz, compared to 162.22±46.22Hz within the IZ (p=0.002). Within the low voltage scar region, the overall PF was 120.86±33.24Hz compared to 188.32±81.36Hz within the IZ (p=0.003). No significant difference in PF was observed within healthy myocardium (112.70±52.06 Hz) compared to components of the IZ within the >1.5mV range (157.61±136.11Hz), p=0.207. The AUC for PF within the overall substrate map and co-localisation with the IZ was 0.67, and 0.73 within low voltage zones (<1.5mV). Conclusions PF mapping may identify critical components of the VT circuit during SR substrate mapping and its utilisation may compliment established substrate mapping approaches. PF guided ablation strategies require further evaluation in future prospective studies.

Direct conversion of cardiac fibroblasts into endothelial-like cells using Sox17 and Erg

Endothelial cells are a heterogeneous population with various organ-specific and conserved functions that are critical to organ development, function, and regeneration. Here we report a Sox17-Erg direct reprogramming approach that uses cardiac fibroblasts to create differentiated endothelial cells that demonstrate endothelial-like molecular and physiological functions in vitro and in vivo. Injection of these induced endothelial cells into myocardial infarct sites after injury results in improved vascular perfusion of the scar region. Furthermore, we use genomic analyses to illustrate that Sox17-Erg reprogramming instructs cardiac fibroblasts toward an arterial-like identity. This results in a more efficient direct conversion of fibroblasts into endothelial-like cells when compared to traditional Etv2-based reprogramming. Overall, this Sox17-Erg direct reprogramming strategy offers a robust tool to generate endothelial cells both in vitro and in vivo, and has the potential to be used in repairing injured tissue.

An Ovine Model Yields Histology and Gene Expression Changes Consistent with Laryngotracheal Stenosis.

Animal models for laryngotracheal stenosis (LTS) are critical to understand underlying mechanisms and study new therapies. Current animal models for LTS are limited by small airway sizes compared to human. The objective of this study was to develop and validate a novel, large animal ovine model for LTS. Sheep underwent either bleomycin-coated polypropylene brush injury to the subglottis (n = 6) or airway stent placement (n = 2) via suspension microlaryngoscopy. Laryngotracheal complexes were harvested 4 weeks following injury or stent placement. For the airway injury group, biopsies (n = 3 at each site) were collected of tracheal scar and distal normal regions, and analyzed for fibrotic gene expression. Lamina propria (LP) thickness was compared between injured and normal areas of trachea. No mortality occurred in sheep undergoing airway injury or stent placement. There was no migration of tracheal stents. After protocol optimization, LP thickness was significantly increased in injured trachea (Sheep #3: 529.0 vs. 850.8 um; Sheep #4: 933.0 vs. 1693.2 um; Sheep #5: 743.7 vs. 1378.4 um; Sheep #6: 305.7 vs. 2257.6 um). A significant 62-fold, 20-fold, 16-fold, 16-fold, and 9-fold change of COL1, COL3, COL5, FN1, and TGFB1 was observed in injured scar specimen relative to unaffected airway, respectively. An ovine LTS model produces histologic and transcriptional changes consistent with fibrosis seen in human LTS. Airway stent placement in this model is safe and feasible. This large airway model is a reliable and reproducible method to assess the efficacy of novel LTS therapies prior to clinical translation. N/A Laryngoscope, 134:4239-4245, 2024.

Abstract PO4-22-03: Intensity Modulated Proton Therapy (IMPT) for the Definitive Adjuvant Management of Women with Breast Cancer: A Single Institutional Experience of 5-Year Oncologic Outcomes

Abstract Purpose: There is limited data reporting the oncologic outcomes of breast cancer patients treated definitively with adjuvant proton beam therapy. Here we report a single institutional experience of oncologic outcomes, treating a predominantly vulnerable breast cancer patient population and compare these to historical standards primarily utilizing photon therapy. Materials and Methods: Unver IRB approval, we retrospectively reviewed 453 definitively treated breast cancer patients from 2016 – 2023 using adjuvant IMPT as part of their cancer care. Patients with recurrent disease, receiving re-irradiation, and those with less than 1-year of follow up were excluded from this analysis. Patients were treated with surgery and systemic therapies as per standards of care. Radiation therapy was administered using pencil beam scanning IMPT with daily image guidance. χ2 and Mann-Whitney U tests were performed to determine differences between select variables. Kaplan-Meier analysis and Cox proportional hazard models were used to analyze overall survival (OS). Results: With a median follow up of 22 months for the entire cohort, 453 patients were treated at XXXX as part of definitive adjuvant management for their breast cancer. Nearly 30% of patients self-identified as black (n=135), average patient age was 54 and 56% (n=255) self-identified as being married with approximately 25% (n=109) of patients having Medicare/Medicaid insurance. 198 patients (43.8%) had an intact breast and the remainder mastectomy of which 37.4% had reconstruction at the time of their radiation. 229 patients (50.7%) received neoadjuvant chemotherapy while 55 patients (12%) received concurrent chemotherapy which was either her2+ directed or Xeloda. The number of patients (%) corresponding to the AJCC 8th edition anatomical staging is as follows: Stage 0: 12 (2.7%); Stage I: 91 (20.1%); Stage 2: 197 (43.6%); Stage 3: 152 (33.6%). Median RT dose delivered for patients receiving comprehensive treatment was 50.4 Gy with 81% of patients receiving a boost to either scar, lumpectomy cavity and/or LN regions. Median RT dose delivered for patients receiving whole breast radiation was 42.56 Gy with a 10 Gy lumpectomy cavity boost. 5-yr OS by stage was 0: 100%; stage I: 98.8%; stage 2: 93.5%; stage 3: 90.8%. Five-year OS for black, white and other race patients were 85.3%, 95.8% and 96%, respectively (White as Ref: HR 3.176, 95% CI: 1.313-7.681, p=0.010 for black patients). For the entire cohort, patients with triple negative disease had a 5-yr OS of 80.4% (HR: 4.33, 95% CI 1.87-10.04, p< 0.001) and there was no difference in OS when insurance status was considered (p=0.378). Conclusions: To the best of our knowledge this represents the largest series of definitively treated breast cancer patients utilizing adjuvant proton therapy and the 5-year OS rates in our analysis coincide with published standards1. Results from the on-going randomized RADCOMP study will provide further guidance as to which patients benefit the most from proton therapy and will further support equivalent oncological outcomes when compared to photon therapy. 1. Weiss A, Chavez-MacGregor M, Lichtensztajn DY, et al. Validation study of the American Joint Committee on Cancer eighth edition prognostic stage compared with the anatomic stage in breast cancer. JAMA Oncol. 4(2):203-209, 2018. Citation Format: Elizabeth Nichols, Gurbani Singh, Desiree Lejano, Sarah McAvoy, Mark Mishra, Melissa Vyfhuis. Intensity Modulated Proton Therapy (IMPT) for the Definitive Adjuvant Management of Women with Breast Cancer: A Single Institutional Experience of 5-Year Oncologic Outcomes [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-22-03.

Fascin-1 limits myosin activity in microglia to control mechanical characterization of the injured spinal cord

BackgroundMechanical softening of the glial scar region regulates axonal regeneration to impede neurological recovery in central nervous system (CNS) injury. Microglia, a crucial cellular component of the glial scar, facilitate neuronal survival and neurological recovery after spinal cord injury (SCI). However, the critical mechanical characterization of injured spinal cord that harmonizes neuroprotective function of microglia remains poorly understood.MethodsSpinal cord tissue stiffness was assessed using atomic force microscopy (AFM) in a mouse model of crush injury. Pharmacological depletion of microglia using PLX5622 was used to explore the effect of microglia on mechanical characterization. Conditional knockout of Fascin-1 in microglia (Fascin-1 CKO) alone or in combination with inhibition of myosin activity was performed to delve into relevant mechanisms of microglia regulating mechanical signal. Immunofluorescence staining was performed to evaluate the related protein levels, inflammatory cells, and neuron survival after SCI. The Basso mouse scale score was calculated to assess functional recovery.ResultsSpinal cord tissue significantly softens after SCI. Microglia depletion or Fascin-1 knockout in microglia limits tissue softening and alters mechanical characterization, which leads to increased tissue pathology and impaired functional recovery. Mechanistically, Fascin-1 inhibits myosin activation to promote microglial migration and control mechanical characterization after SCI.ConclusionsWe reveal that Fascin-1 limits myosin activity to regulate mechanical characterization after SCI, and this mechanical signal should be considered in future approaches for the treatment of CNS diseases.

3D bioprinted aged human post-infarct myocardium tissue model.

Fibrotic tissue formed after myocardial infarction (MI) can be as detrimental as MI itself. However, current in vitro cardiac fibrosis models fail to recapitulate the complexities of post-MI tissue. Moreover, although MI and subsequent fibrosis is most prominent in the aged population, the field suffers from inadequate aged tissue models. Herein, an aged human post-MI tissue model, representing the native microenvironment weeks after initial infarction, is engineered using three-dimensional bioprinting via creation of individual bioinks to specifically mimic three distinct regions: remote, border, and scar. The aged post-MI tissue model is engineered through combination of gelatin methacryloyl, methacrylated hyaluronic acid, aged type I collagen, and photoinitiator at variable concentrations with different cell types, including aged human induced pluripotent stem cell-derived cardiomyocytes, endothelial cells, cardiac fibroblasts, and cardiac myofibroblasts, by introducing a methodology which utilizes three printheads of the bioprinter to model aged myocardium. Then, using cell-specific proteins, the cell types that comprised each region are confirmed using immunofluorescence. Next, the beating characteristics are analyzed. Finally, the engineered aged post-MI tissue model is used as a benchtop platform to assess the therapeutic effects of stem cell-derived extracellular vesicles on the scar region. As a result, high viability (>74%) was observedin each region of the printed model. Constructs demonstrated functional behavior, exhibiting a beating velocity of 6.7 μm/s and a frequency of 0.3 Hz. Finally, the effectiveness of hiPSC-EV and MSC-EV treatment was assessed. While hiPSC-EV treatment showed no significant changes, MSC-EV treatment notably increased cardiomyocyte beating velocity, frequency, and confluency, suggesting a regenerative potential. In conclusion, we envision that our approach of modeling post-MI aged myocardium utilizing three printheads of the bioprinter may be utilized for various applications in aged cardiac microenvironment modeling and testing novel therapeutics.

A comparative study in elective repair of large incisional hernias using on-lay mesh vs. sub-lay mesh: a meta-analysis

Ventral abdominal wall incisional hernia is defined as a defect in the musculo-fascial layers of the abdominal wall in the region of the postoperative scar. There is a slight increase in the incidence of incisional hernia in the female gender. The higher percentage of incisional hernia in females might be due to laxity of abdominal wall muscles after multiple pregnancies and also an increased incidence of obesity in females. To assess incisional hernia repair using two different techniques: on-lay mesh and sub-lay mesh, as regards operative time, postoperative recurrence, wound infection, seroma, hematoma, and flap necrosis. Pubmed, Web of Science, and Scopus were searched on 15 March 2022. The keywords incisional hernia, sub-lay mesh on-lay mesh, retromuscular mesh, and polypropylene. According to our results, there is a statistical difference between onlay and sublay regarding intra-operative time as sublay mesh is more time-consuming. Regarding postoperative complications, there is no statistical difference in recurrence, seroma, hematoma, flap necrosis, and infection but there is a statistical difference regarding in hospital stay as patients with sub-lay repair stays less than only.

Single-cell, single-nucleus, and spatial transcriptomics characterization of the immunological landscape in the healthy and PSC human liver

Primary sclerosing cholangitis (PSC) is an immune-mediated cholestatic liver disease for which there is an unmet need to understand the cellular composition of the affected liver and how it underlies disease pathogenesis. We aimed to generate a comprehensive atlas of the PSC liver using multi-omic modalities and protein-based functional validation. We employed single-cell and single-nucleus RNA sequencing (47,156 cells and 23,000 nuclei) and spatial transcriptomics (one sample by 10x Visium and five samples with Nanostring GeoMx DSP) to profile the cellular ecosystem in 10 PSC livers. Transcriptomic profiles were compared to 24 neurologically deceased donor livers (107,542 cells) and spatial transcriptomics controls, as well as 18,240 cells and 20,202 nuclei from three PBC livers. Flow cytometry was performed to validate PSC-specific differences in immune cell phenotype and function. PSC explants with parenchymal cirrhosis and prominent periductal fibrosis contained a population of cholangiocyte-like hepatocytes that were surrounded by diverse immune cell populations. PSC-associated biliary, mesenchymal, and endothelial populations expressed chemokine and cytokine transcripts involved in immune cell recruitment. Additionally, expanded CD4+ T cells and recruited myeloid populations in the PSC liver expressed the corresponding receptors to these chemokines and cytokines, suggesting potential recruitment. Tissue-resident macrophages, by contrast, were reduced in number and exhibited a dysfunctional and downregulated inflammatory response to lipopolysaccharide and interferon-γ stimulation. We present a comprehensive atlas of the PSC liver and demonstrate an exhaustion-like phenotype of myeloid cells and markers of chronic cytokine expression in late-stage PSC lesions. This atlas expands our understanding of the cellular complexity of PSC and has potential to guide the development of novel treatments. Primary sclerosing cholangitis (PSC) is a rare liver disease characterized by chronic inflammation and irreparable damage to the bile ducts, which eventually results in liver failure. Due to a limited understanding of the underlying pathogenesis of disease, treatment options are limited. To address this, we sequenced healthy and diseased livers to compare the activity, interactions, and localization of immune and non-immune cells. This revealed that hepatocytes lining PSC scar regions co-express cholangiocyte markers, whereas immune cells infiltrate the scar lesions. Of these cells, macrophages, which typically contribute to tissue repair, were enriched in immunoregulatory genes and demonstrated a lack of responsiveness to stimulation. These cells may be involved in maintaining hepatic inflammation and could be a target for novel therapies.

Re-entry in models of cardiac ventricular tissue with scar represented as a Gaussian random field.

Introduction: Fibrotic scar in the heart is known to act as a substrate for arrhythmias. Regions of fibrotic scar are associated with slowed or blocked conduction of the action potential, but the detailed mechanisms of arrhythmia formation are not well characterised and this can limit the effective diagnosis and treatment of scar in patients. The aim of this computational study was to evaluate different representations of fibrotic scar in models of 2D 10 10 cm ventricular tissue, where the region of scar was defined by sampling a Gaussian random field with an adjustable length scale of between 1.25 and 10.0 mm. Methods: Cellular electrophysiology was represented by the Ten Tusscher 2006 model for human ventricular cells. Fibrotic scar was represented as a spatially varying diffusion, with different models of the boundary between normal and fibrotic tissue. Dispersion of activation time and action potential duration (APD) dispersion was assessed in each sample by pacing at an S1 cycle length of 400 ms followed by a premature S2 beat with a coupling interval of 323 ms. Vulnerability to reentry was assessed with an aggressive pacing protocol. In all models, simulated fibrosis acted to delay activation, to increase the dispersion of APD, and to generate re-entry. Results: A higher incidence of re-entry was observed in models with simulated fibrotic scar at shorter length scale, but the type of model used to represent fibrotic scar had a much bigger influence on the incidence of reentry. Discussion: This study shows that in computational models of fibrotic scar the effects that lead to either block or propagation of the action potential are strongly influenced by the way that fibrotic scar is represented in the model, and so the results of computational studies involving fibrotic scar should be interpreted carefully.