Virtual surgical planning and mirrored, 3-dimensionally printed guides for corrective clavicle osteotomies in clavicle malunions and nonunions.

BACKGROUND: The objective of this study was to retrospectively review clinical and radiographic outcomes of patients who underwent corrective osteotomies for clavicle malunion and internal fixation for nonunion using a combination of virtual surgical planning, patient-specific 3-dimensional (3D)-printed clavicles, and 3D-printed cutting guides manufactured at the point of care. METHODS: Between 2015 and 2021, 18 patients underwent corrective osteotomy for a clavicle malunion (7 shoulders) or internal fixation for a clavicle nonunion (11 shoulders). There were 11 male and 7 female individuals with an average patient age of 43.9 (range 19-76) years. All patients underwent computed tomography evaluation of both clavicles. The DICOM files were manually segmented, virtual surgical planning was performed selectively using commercially available software, and a mirrored version of the normal clavicle was 3D printed along with a 3D-printed replica of the affected clavicle. Three-dimensionally printed mirrored clavicles were used in all cases to ensure adequate restoration of the shape and length of the clavicle and to precontour fixation plates. Virtual surgical planning and 3D-printed cutting guides for osteotomy were used in 4 of 18 (22%) patients. Either cancellous or structural intercalary bone grafting was used in 15 of 18 (83%) cases. Patients were contacted postoperatively to determine clinical outcome scores. Preoperative, early postoperative, and late postoperative radiographs were reviewed to assess for union and complications. The average follow-up time was 24.9 months. RESULTS: Radiographic evaluation at the most recent follow-up demonstrated adequate restoration of length and successful union for all shoulders. There were no complications or reoperations. Postoperative patient-reported outcomes could be obtained in 16 of 18 (88.9%) patients. At the most recent follow-up, the mean visual analog scale for pain was 2.38 points (range, 1-7), the mean shoulder American Shoulder and Elbow Surgeons score was 73.2 points (range, 25-100), and the mean Patient-Reported Outcome Measurement Information System Upper Extremity score was 26 points (range, 7-35). All (100%) the patients were satisfied with their outcome (9 very satisfied, 7 satisfied), and their mean subjective shoulder value was 73% (range, 10%-100%). However, 2 patients complained of hardware-related symptoms, and 1 patient had return of preoperative symptoms after an interim 2 years of pain relief. CONCLUSION: The use of mirrored 3D-printed clavicles combined with virtual surgical planning and patient-specific 3D guides provides a reliable technique for restoring native anatomy when performing corrective osteotomies for clavicle malunion or internal fixation for clavicle nonunion, with a high rate of satisfactory clinical and radiographic outcomes.

Three-Dimensional Modeling for Augmented and Virtual Reality-Based Posterior Fossa Approach Selection Training: Technical Overview of Novel Open-Source Materials.

BACKGROUND: Selection of skull base approaches is a critical skill for complex cranial surgery, which demands nuanced understanding of neuroanatomy and pathology. OBJECTIVE: To develop novel pedagogical resources for approach selection education and assessment. METHODS: A prospectively maintained skull base registry was screened for posterior fossa tumors amenable to 3-dimensional (3D) modeling of multiple operative approaches. Inclusion criteria were high-resolution preoperative and postoperative computed tomography and MRI studies (≤1 mm) and consensus that at least 3 posterior fossa craniotomies would provide feasible access. Cases were segmented using Mimics and modeled using 3-Matic. Clinical Vignettes, Approach Selection Questionnaire, and Clinical Application Questionnaire were compiled for implementation as a teaching/testing tool. RESULTS: Seven cases were selected, each representing a major posterior fossa approach group. 3D models were rendered using clinical imaging for the primary operative approach, as well as a combination of laboratory neuroanatomic data and extrapolation from comparable craniotomies to generate 2 alternative approaches in each patient. Modeling data for 3D figures were uploaded to an open-sourced database in a platform-neutral fashion (.x3d) for virtual/augmented reality and 3D printing applications. A semitransparent model of each approach without pathology and with key deep structures visualized was also modeled and included for comprehensive understanding. CONCLUSION: We report a novel series of open-source 3D models for skull base approach selection training, with supplemental resources. To the best of our knowledge, this is the first such series designed for pedagogical purposes in skull base surgery or centered on open-source principles.

Accuracy and Precision of the Computed Tomographic Angiography Perforator Localization Technique for Virtual Surgical Planning of Composite Osteocutaneous Fibular Free Flaps in Head and Neck Reconstruction.

BACKGROUND: Virtual surgical planning (VSP), computer aided design/computer aided modeling, and 3-dimensional printing technology have been shown to improve surgical accuracy and efficiency in head and neck reconstruction. However, persisting criticism of the technology is that it does not adequately address the soft tissue-related aspects of reconstructive surgery. Prior publication on the computed tomographic angiography (CTA) perforator localization technique has demonstrated how soft tissue planning can be incorporated directly into existing VSP workflows. PURPOSE: The aim of this study is to prospectively assess the accuracy, precision, negative predictive value (NPV), and positive predictive value (PPV) of the CTA perforator localization technique for VSP of osteocutaneous fibular free flaps. MATERIALS AND METHODS: A prospective observational study in a consecutive cohort of subjects undergoing VSP of osteocutaneous fibular free flaps at Mayo Clinic between 2018 and 2020 was completed. All cutaneous perforators from the peroneal system of the selected donor leg were identified preoperatively through a previously reported CTA tracing method and registered into the VSP. Perforators were classified as primary or secondary based on whether the perforators were targeted for use in the final reconstructive plan. Perforator measurements obtained from the VSP were cross-referenced with intraoperatively obtained measurements of actual perforator locations to calculate accuracy, precision, NPV, PPV, sensitivity, and specificity of the CTA localization technique. RESULTS: Sixty consecutive subjects were enrolled in the study. A total of 141 perforators were identified preoperatively on CTA and 145 perforators were identified on operative exposure. One perforator identified on preoperative CTA was not identified on surgical exposure (false positive perforator). Six perforators were identified on operative exposure alone without recognition on preoperative CTA (false negative perforators). The accuracy of CTA perforator identification was 96.52%. Median precision of perforator localization was 0.3 cm (standard deviation 0.40) between CTA and operatively identified locations. PPV of the technique was 99.29% and NPV was 90.00%. CONCLUSION: The CTA localization technique for identifying and incorporating cutaneous perforator locations into VSP of osteocutaneous fibular free flaps is a reliable, accurate, and precise technique to employ in the modern paradigm of guided surgery for head and neck reconstruction.

EPPOCRATIS: Expedited Preoperative Point-of-Care Reduction of Fractures to Normalized Anatomy and Three-Dimensional Printing to Improve Surgical Outcomes.

SUMMARY: Virtual surgical planning and three-dimensional printing have been invaluable tools in craniomaxillofacial surgery. From planning head and neck reconstruction to orthognathic surgery and secondary reconstruction of maxillofacial trauma, virtual surgical planning and three-dimensional printing allow the surgeon to rehearse the surgical plan and use patient-specific surgical guides for carrying out the plan accurately. However, the process of virtual surgical planning and three-dimensional printing requires time and coordination between the surgeon on one hand and the biomedical engineers and designers on the other hand. Outsourcing to third-party companies contributes to inefficiencies in this process. Advances in surgical planning software and three-dimensional printing technology have enabled the integration of virtual surgical planning and three-dimensional printing at the treating hospital, the point of care. This allows for expedited use of this process in semiurgent surgical cases and acute facial trauma cases by bringing the surgeon, radiologist, biomedical engineers, and designers to the point of care. In this article, the authors present the utility of EPPOCRATIS, expedited preoperative point of care reduction of fractures to normalized anatomy and three-dimensional printing to improve surgical outcomes, in the management of acute facial trauma.

Point of care virtual surgical planning and 3D printing in facial gender confirmation surgery: a narrative review.

Facial gender confirmation surgery (FGCS) is a powerful set of procedures in the armamentarium of plastic surgeons that can transform the male face into a gender-congruent female face and provide the transgender individual with improved quality of life, positive body image and help in social integration. The goals of the FGCS procedures are to address the individual patients' concerns and expectations about their facial appearance, offer safely executed surgery, minimize complications, and optimize surgical outcomes. Pre-operative computed tomography (CT) scanning and three-dimensional (3D) reconstruction before facial feminization or masculinization delineates important skeletal and sinus anatomy and can also be a useful tool in patient consultation. Virtual surgical planning (VSP) is a valuable tool in facial surgery. From free flap bony reconstruction after tumor resection and orthognathic surgery to craniosynostosis planning, VSP has become widely utilized in modern day cranio-maxillofacial surgery. The use of patient-specific cutting guides and implants helps in improving symmetry and safety of these procedures. Furthermore, 3D printed models are valuable tools in patient education and counseling prior to surgery. In this article we describe our approach to FGCS through the integration of point of care (POC) VSP and 3D printing (3DP) to help deliver safer and accurate FGCS outcomes.

Association of Virtual Surgical Planning With External Incisions in Complex Maxillectomy Reconstruction.

Importance: Maxillectomy can commonly be performed through a transoral approach, but maxillectomy defect reconstruction can be difficult to precisely design, contour, and inset through this approach. Objective: To evaluate whether the use of virtual surgical planning (VSP) and 3-dimensional (3-D) modeling is associated with a decrease in the requirement of lateral rhinotomy (LR) for patients undergoing total and partial maxillectomy reconstruction. Design, Setting, and Participants: This retrospective cohort study was conducted among patients undergoing subtotal or total maxillectomy with microvascular free flap reconstruction with or without VSP and 3-D modeling at a single tertiary care academic medical center between January 1, 2008, and October 3, 2019. Interventions: Maxillectomy and free flap reconstruction with or without VSP. Main Outcomes and Measures: Necessity of LR or other external incision for contouring, placement, and fixation of reconstruction as well as surgical complications. Results: Fifteen patients (12 men [80%]; mean age, 64 years) underwent maxillectomy with free flap reconstruction without VSP. Eight patients (53%) in this group underwent total maxillectomy, and 4 patients in this group (27%) underwent partial maxillectomy. Twenty-three patients (18 men [78%]; mean age, 58 years) underwent maxillectomy with free flap reconstruction and VSP and 3-D modeling. Twelve of these patients (52%) underwent total maxillectomy, and 11 (48%) underwent partial maxillectomy. Lateral rhinotomy was necessary for 1 patient (4%) in the VSP group vs 12 patients (80%; 95% CI, 54%-98%) in the pre-VSP group. There were no LR complications in the VSP group vs 6 in the pre-VSP group. Among both groups, 14 patients underwent fibula free flap, 22 patients underwent subscapular system free flap, and 2 patients underwent cutaneous or osteocutaneous radial forearm free flap. There were no flap failures in the LR group and 1 flap failure in the group without LR. Conclusions and Relevance: This cohort study suggests that the use of VSP and 3-D modeling for maxillectomy reconstruction is associated the a decrease in the need for external incisions without compromising reconstructive flap utility.

A guideline for 3D printing terminology in biomedical research utilizing ISO/ASTM standards.

First patented in 1986, three-dimensional (3D) printing, also known as additive manufacturing or rapid prototyping, now encompasses a variety of distinct technology types where material is deposited, joined, or solidified layer by layer to create a physical object from a digital file. As 3D printing technologies continue to evolve, and as more manuscripts describing these technologies are published in the medical literature, it is imperative that standardized terminology for 3D printing is utilized. The purpose of this manuscript is to provide recommendations for standardized lexicons for 3D printing technologies described in the medical literature. For all 3D printing methods, standard general ISO/ASTM terms for 3D printing should be utilized. Additional, non-standard terms should be included to facilitate communication and reproducibility when the ISO/ASTM terms are insufficient in describing expository details. By aligning to these guidelines, the use of uniform terms for 3D printing and the associated technologies will lead to improved clarity and reproducibility of published work which will ultimately increase the impact of publications, facilitate quality improvement, and promote the dissemination and adoption of 3D printing in the medical community.

Short and long-term outcomes of three-dimensional printed surgical guides and virtual surgical planning versus conventional methods for fibula free flap reconstruction of the mandible: Decreased nonunion and complication rates.

BACKGROUND: To determine whether virtual surgical planning and three-dimensional printed cutting guides (3D/VSP) improved radiographic bone union compared to conventional methods (CM) in fibula free flap (FFF) reconstruction of the mandibles. METHODS: Retrospective study from the years 2000-2018 at a tertiary hospital. Osseous union was evaluated by a radiologist blinded to each patient's treatment. RESULTS: Two hundred sixty patients who underwent FFF tissue transfer, 28 with VSP and 3D cutting guides. Bony union was not achieved in 46 (20%) patients who underwent CM compared to 1 (4%) of patients with VSP and guides (p = 0.036). FFF complication was significantly higher in CM with 87 patients (38%) compared to three patients (11%) in 3D/VSP (p = 0.005). Median time to bony union for patients who underwent CM was 1.4 years compared to 0.8 years in 3D/VSP. CONCLUSIONS: 3D/VSP reduced the rate of radiographic nonunion and flap-related complications in FFF reconstruction for mandibular defects.

Intracranial vasculature 3D printing: review of techniques and manufacturing processes to inform clinical practice.

BACKGROUND: In recent years, three-dimensional (3D) printing has been increasingly applied to the intracranial vasculature for patient-specific surgical planning, training, education, and research. Unfortunately, though, much of the prior literature regarding 3D printing has focused on the end-product and not the process. In addition, for 3D printing/manufacturing to occur on a large scale, challenges and bottlenecks specific to each modeled anatomy must be overcome. MAIN BODY: In this review article, limitations and considerations of each 3D printing processing step, as they relate to printing individual intracranial vasculature models and providing an active clinical service for a quaternary care center, are discussed. Relevant advantages and disadvantages of the available acquisition techniques (computed tomography, magnetic resonance, and digital subtraction angiography) are reviewed. Specific steps in segmentation, processing, and creation of a printable file may impede the workflow or degrade the fidelity of the printed model and are, therefore, given added attention. The various available printing techniques are compared with respect to printing the intracranial vasculature. Finally, applications are discussed, and a variety of example models are shown. CONCLUSION: In this review we provide insight into the manufacturing of 3D models of the intracranial vasculature that may facilitate incorporation into or improve utility of 3D vascular models in clinical practice.

Novel Geometry of an Extended Length Chimeric Scapular Free Flap for Hemimandibular Reconstruction: Nuances of the Technique Streamlined by In-House Virtual Surgical Planning and 3D Printing for a Severely Vessel-Depleted Neck.

Subscapular-based flaps have historically maintained an unparalleled ability to provide a multitude of bone and soft tissue components based on a single vascular pedicle. However, these flaps are often not thought of as an ideal choice for composite defects requiring extended lengths of bone for reconstruction. The ability to harvest long segments of bone and reliably perform multiple contouring osteotomies is fundamental to long-span composite mandibular reconstruction, and microvascular surgeons are often met with significant reconstructive challenges when fibular free flaps cannot be used owing to variant vascular anatomy or occlusive atherosclerotic disease in these specific clinical scenarios. This challenge is further compounded by treatment-related vessel depletion in the neck, which reduces the availability of suitable recipient vessels in close proximity to the reconstruction. We present a case in which all of the aforementioned challenges presented in a single individual, who concomitantly required hemimandibular reconstruction with treatment related vessel depletion in the neck and unsuitable bilateral vascular anatomy in the legs precluding the use of a fibular free flap. This case demonstrates a previously unreported flap component geometry for hemimandibular reconstruction using an extended-length chimeric scapular free flap with scapular tip, lateral scapular border, and parascapular fasciocutaneous skin paddle components.

Cardioprotective Actions of the Annexin-A1 N-Terminal Peptide, Ac2-26, Against Myocardial Infarction.

The anti-inflammatory, pro-resolving annexin-A1 protein acts as an endogenous brake against exaggerated cardiac necrosis, inflammation, and fibrosis following myocardial infarction (MI) in vivo. Little is known, however, regarding the cardioprotective actions of the N-terminal-derived peptide of annexin A1, Ac2-26, particularly beyond its anti-necrotic actions in the first few hours after an ischemic insult. In this study, we tested the hypothesis that exogenous Ac2-26 limits cardiac injury in vitro and in vivo. Firstly, we demonstrated that Ac2-26 limits cardiomyocyte death both in vitro and in mice subjected to ischemia-reperfusion (I-R) injury in vivo (Ac2-26, 1 mg/kg, i.v. just prior to post-ischemic reperfusion). Further, Ac2-26 (1 mg/kg i.v.) reduced cardiac inflammation (after 48 h reperfusion), as well as both cardiac fibrosis and apoptosis (after 7-days reperfusion). Lastly, we investigated whether Ac2-26 preserved cardiac function after MI. Ac2-26 (1 mg/kg/day s.c., osmotic pump) delayed early cardiac dysfunction 1 week post MI, but elicited no further improvement 4 weeks after MI. Taken together, our data demonstrate the first evidence that Ac2-26 not only preserves cardiomyocyte survival in vitro, but also offers cardioprotection beyond the first few hours after an ischemic insult in vivo. Annexin-A1 mimetics thus represent a potential new therapy to improve cardiac outcomes after MI.

Creating patient-specific anatomical models for 3D printing and AR/VR: a supplement for the 2018 Radiological Society of North America (RSNA) hands-on course.

Advanced visualization of medical image data in the form of three-dimensional (3D) printing continues to expand in clinical settings and many hospitals have started to adapt 3D technologies to aid in patient care. It is imperative that radiologists and other medical professionals understand the multi-step process of converting medical imaging data to digital files. To educate health care professionals about the steps required to prepare DICOM data for 3D printing anatomical models, hands-on courses have been delivered at the Radiological Society of North America (RSNA) annual meeting since 2014. In this paper, a supplement to the RSNA 2018 hands-on 3D printing course, we review methods to create cranio-maxillofacial (CMF), orthopedic, and renal cancer models which can be 3D printed or visualized in augmented reality (AR) or virtual reality (VR).

Computed Tomographic Angiography Perforator Localization for Virtual Surgical Planning of Osteocutaneous Fibular Free Flaps in Head and Neck Reconstruction.

Virtual surgical planning (VSP), computer-aided design and computer-aided modeling, and 3-dimensional printing are 3 distinct technologies that have become increasingly employed in head and neck oncology and microvascular reconstruction. Although each of these technologies have long been utilized for treatment planning in other surgical disciplines such as craniofacial surgery, trauma surgery, temporomandibular joint surgery, and orthognathic surgery, its widespread use in head and neck reconstructive surgery remains a much more recent advent. In response to the growing trend of VSP being used for the planning of fibular free flaps in head and neck reconstruction, some surgeons have questioned the technology's implementation based upon its perceived inadequacy in addressing other reconstructive considerations beyond hard tissue anatomy. Detractors of VSP for head and neck reconstruction highlight its lack of capability in accounting for multiple reconstructive factors, such as recipient vessel selection, vascular pedicle reach, need for dead space obliteration, and skin paddle perforator location. It is with this premise in mind that we report a simple technique for anatomically localizing peroneal artery perforators during VSP for osteocutaneous fibular free flaps in which both bone and a soft tissue skin paddle are required for ablative reconstruction. The technique allows for anatomic perforator localization during the VSP session based solely upon data existent within the preoperative computed tomographic angiography (CTA) and it does not require any modifications to preoperative clinical workflows. It is the authors' presumption that many surgeons in the field are unaware of this planning capability within the context of modern VSP for head and neck reconstruction. The primary purpose of this manuscript is to introduce and further familiarize surgeons with the technique of CTA perforator localization as a method of improving intraoperative fidelity for VSP of osteocutaneous fibular free flaps.

Novel Patient-Specific 3-Dimensional Printed Fixation Tray for Mandibular Reconstruction With Fibular Free Flaps.

Segmental mandibular defects secondary to infectious, traumatic, and pathologic conditions can be debilitating because of their impact on function and facial esthetics. Several reconstructive techniques are available, with vascularized flaps commonly used for the reconstruction of large bony or composite segmental defects. The free fibular flap for mandibular reconstruction is well documented and remains a commonly used flap because of its bone length, versatility, distant location from the head and neck region that allows for a 2-team approach, and ability to simultaneously place endosseous implants. Virtual surgical planning (VSP) and guided resection and reconstruction of maxillofacial defects have facilitated complex 3-dimensional (3D) reconstruction. The accuracy and fidelity of VSP are dependent on the intraoperative execution of the VSP, with computer-aided design and computer-aided modeling of patient-specific cutting guides and hardware providing a template for its execution. The goal of this report is to describe the authors' experience with the use of a novel 3D printed fixation tray designed from the VSP data. It provides dual functionality by aiding in alignment and stabilization of the fibular segments and concomitantly providing patient-specific anatomic references for indexing of bony and soft tissue components. This tray enables rapid ex vivo configuration of the fibula segment(s) with the reconstruction bar relative to the native mandibular segments and allows the compiled construct to be transferred to the head and neck for insetting as a precisely configured single unit.

Small-molecule-biased formyl peptide receptor agonist compound 17b protects against myocardial ischaemia-reperfusion injury in mice.

Effective treatment for managing myocardial infarction (MI) remains an urgent, unmet clinical need. Formyl peptide receptors (FPR) regulate inflammation, a major contributing mechanism to cardiac injury following MI. Here we demonstrate that FPR1/FPR2-biased agonism may represent a novel therapeutic strategy for the treatment of MI. The small-molecule FPR1/FPR2 agonist, Compound 17b (Cmpd17b), exhibits a distinct signalling fingerprint to the conventional FPR1/FPR2 agonist, Compound-43 (Cmpd43). In Chinese hamster ovary (CHO) cells stably transfected with human FPR1 or FPR2, Compd17b is biased away from potentially detrimental FPR1/2-mediated calcium mobilization, but retains the pro-survival signalling, ERK1/2 and Akt phosphorylation, relative to Compd43. The pathological importance of the biased agonism of Cmpd17b is demonstrable as superior cardioprotection in both in vitro (cardiomyocytes and cardiofibroblasts) and MI injury in mice in vivo. These findings reveal new insights for development of small molecule FPR agonists with an improved cardioprotective profile for treating MI.

Implementation of iterative metal artifact reduction in the pre-planning-procedure of three-dimensional physical modeling.

BACKGROUND: To assess the impact of metal artifact reduction techniques in 3D printing by evaluating image quality and segmentation time in both phantom and patient studies with dental restorations and/or other metal implants. An acrylic denture apparatus (Kilgore Typodent, Kilgore International, Coldwater, MI) was set in a 20 cm water phantom and scanned on a single-source CT scanner with gantry tilting capacity (SOMATOM Edge, Siemens Healthcare, Forchheim, Germany) under 5 scenerios: (1) Baseline acquisition at 120 kV with no gantry tilt, no jaw spacer, (2) acquisition at 140 kV, (3) acquisition with a gantry tilt at 15°, (4) acquisition with a non-radiopaque jaw spacer and (5) acquisition with a jaw spacer and a gantry tilt at 15°. All acquisitions were reconstructed both with and without a dedicated iterative metal artifact reduction algorithm (MAR). Patients referred for a head-and-neck exam were included into the study. Acquisitions were performed on the same scanner with 120 kV and the images were reconstructed with and without iterative MAR. Segmentation was performed on a dedicated workstation (Materialise Interactive Medical Image Control Systems; Materialise NV, Leuven, Belgium) to quantify volume of metal artifact and segmentation time. RESULTS: In the phantom study, the use of gantry tilt, jaw spacer and increased tube voltage showed no benefit in time or artifact volume reduction. However the jaw spacer allowed easier separation of the upper and lower jaw and a better display of the teeth. The use of dedicated iterative MAR significantly reduced the metal artifact volume and processing time. Same observations were made for the four patients included into the study. CONCLUSION: The use of dedicated iterative MAR and jaw spacer substantially reduced metal artifacts in the head-and-neck CT acquisitions, hence allowing a faster 3D segmentation workflow.

HNO/cGMP-dependent antihypertrophic actions of isopropylamine-NONOate in neonatal rat cardiomyocytes: potential therapeutic advantages of HNO over NO.

Nitroxyl (HNO) is a redox congener of NO. We now directly compare the antihypertrophic efficacy of HNO and NO donors in neonatal rat cardiomyocytes and compare their contributing mechanisms of actions in this setting. Isopropylamine-NONOate (IPA-NO) elicited concentration-dependent inhibition of endothelin-1 (ET1)-induced increases in cardiomyocyte size, with similar suppression of hypertrophic genes. Antihypertrophic IPA-NO actions were significantly attenuated by l-cysteine (HNO scavenger), Rp-8-pCTP-cGMPS (cGMP-dependent protein kinase inhibitor), and 1-H-(1,2,4)-oxodiazolo-quinxaline-1-one [ODQ; to target soluble guanylyl cyclase (sGC)] but were unaffected by carboxy-PTIO (NO scavenger) or CGRP8-37 (calcitonin gene-related peptide antagonist). Furthermore, IPA-NO significantly increased cardiomyocyte cGMP 3.5-fold (an l-cysteine-sensitive effect) and stimulated sGC activity threefold, without detectable NO release. IPA-NO also suppressed ET1-induced cardiomyocyte superoxide generation. The pure NO donor diethylamine-NONOate (DEA-NO) reproduced these IPA-NO actions but was sensitive to carboxy-PTIO rather than l-cysteine. Although IPA-NO stimulation of purified sGC was preserved under pyrogallol oxidant stress (in direct contrast to DEA-NO), cardiomyocyte sGC activity after either donor was attenuated by this stress. Excitingly IPA-NO also exhibited acute antihypertrophic actions in response to pressure overload in the intact heart. Together these data strongly suggest that IPA-NO protection against cardiomyocyte hypertrophy is independent of both NO and CGRP but rather utilizes novel HNO activation of cGMP signaling. Thus HNO acutely limits hypertrophy independently of NO, even under conditions of elevated superoxide. Development of longer-acting HNO donors may thus represent an attractive new strategy for the treatment of cardiac hypertrophy, as stand-alone and/or add-on therapy to standard care.

The soluble guanylyl cyclase activator bay 58-2667 selectively limits cardiomyocyte hypertrophy.

BACKGROUND: Although evidence now suggests cGMP is a negative regulator of cardiac hypertrophy, the direct consequences of the soluble guanylyl cyclase (sGC) activator BAY 58-2667 on cardiac remodeling, independent of changes in hemodynamic load, has not been investigated. In the present study, we tested the hypothesis that the NO(•)-independent sGC activator BAY 58-2667 inhibits cardiomyocyte hypertrophy in vitro. Concomitant impact of BAY 58-2667 on cardiac fibroblast proliferation, and insights into potential mechanisms of action, were also sought. Results were compared to the sGC stimulator BAY 41-2272. METHODS: Neonatal rat cardiomyocytes were incubated with endothelin-1 (ET(1), 60nmol/L) in the presence and absence of BAY 41-2272 and BAY 58-2667 (0.01-0.3 µmol/L). Hypertrophic responses and its triggers, as well as cGMP signaling, were determined. The impact of both sGC ligands on basal and stimulated cardiac fibroblast proliferation in vitro was also determined. RESULTS: We now demonstrate that BAY 58-2667 (0.01-0.3 µmol/L) elicited concentration-dependent antihypertrophic actions, inhibiting ET(1)-mediated increases in cardiomyocyte 2D area and de novo protein synthesis, as well as suppressing ET(1)-induced cardiomyocyte superoxide generation. This was accompanied by potent increases in cardiomyocyte cGMP accumulation and activity of its downstream signal, vasodilator-stimulated phosphoprotein (VASP), without elevating cardiomyocyte cAMP. In contrast, submicromolar concentrations of BAY 58-2667 had no effect on basal or stimulated cardiac fibroblast proliferation. Indeed, only at concentrations ≥10 µmol/L was inhibition of cardiac fibrosis seen in vitro. The effects of BAY 58-2667 in both cell types were mimicked by BAY 41-2272. CONCLUSIONS: Our results demonstrate that BAY 58-2667 elicits protective, cardiomyocyte-selective effects in vitro. These actions are associated with sGC activation and are evident in the absence of confounding hemodynamic factors, at low (submicromolar) concentrations. Thus this distinctive sGC ligand may potentially represent an alternative therapeutic approach for limiting myocardial hypertrophy.

Nitroxyl (HNO) stimulates soluble guanylyl cyclase to suppress cardiomyocyte hypertrophy and superoxide generation.

BACKGROUND: New therapeutic targets for cardiac hypertrophy, an independent risk factor for heart failure and death, are essential. HNO is a novel redox sibling of NO• attracting considerable attention for the treatment of cardiovascular disorders, eliciting cGMP-dependent vasodilatation yet cGMP-independent positive inotropy. The impact of HNO on cardiac hypertrophy (which is negatively regulated by cGMP) however has not been investigated. METHODS: Neonatal rat cardiomyocytes were incubated with angiotensin II (Ang II) in the presence and absence of the HNO donor Angeli's salt (sodium trioxodinitrate) or B-type natriuretic peptide, BNP (all 1 µmol/L). Hypertrophic responses and its triggers, as well as cGMP signaling, were determined. RESULTS: We now demonstrate that Angeli's salt inhibits Ang II-induced hypertrophic responses in cardiomyocytes, including increases in cardiomyocyte size, de novo protein synthesis and ß-myosin heavy chain expression. Angeli's salt also suppresses Ang II induction of key triggers of the cardiomyocyte hypertrophic response, including NADPH oxidase (on both Nox2 expression and superoxide generation), as well as p38 mitogen-activated protein kinase (p38MAPK). The antihypertrophic, superoxide-suppressing and cGMP-elevating effects of Angeli's salt were mimicked by BNP. We also demonstrate that the effects of Angeli's salt are specifically mediated by HNO (with no role for NO• or nitrite), with subsequent activation of cardiomyocyte soluble guanylyl cyclase (sGC) and cGMP signaling (on both cGMP-dependent protein kinase, cGK-I and phosphorylation of vasodilator-stimulated phosphoprotein, VASP). CONCLUSIONS: Our results demonstrate that HNO prevents cardiomyocyte hypertrophy, and that cGMP-dependent NADPH oxidase suppression contributes to these antihypertrophic actions. HNO donors may thus represent innovative pharmacotherapy for cardiac hypertrophy.