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BACKGROUND AND OBJECTIVES: The optimal timing between preoperative embolization of hypervascular metastatic bone lesions and surgery has yet to be established. Our analysis sought to evaluate embolization timing impacts blood loss, transfusion risk, and operative time in patients with hypervascular primary tumors. METHODS: We identified patients with renal cell (RCC) or thyroid carcinoma undergoing surgery between 1992 and 2023. Patients were segregated into the following cohorts: (1) no embolization preoperatively, (2) surgery <24 h of embolization, and (3) surgery >24 h after embolization. Multivariate logistic regression analyses were performed to assess the effect of embolization timing while controlling for confounding variables. RESULTS: No differences were seen in all evaluated outcomes between immediate and delayed embolization cohorts. No differences in estimated blood loss were seen between the immediate (OR: 0.685, 95% CI: 0.159-2.949; p = 0.611) and delayed (OR: 0.568, 95% CI: 0.093-3.462; p = 0.539) surgery cohorts compared with patients without embolization. Surgery >24 h after embolization was not associated with a higher risk of prolonged operative time (OR: 13.499, 95% CI: 0.832-219.146; p = 0.067). CONCLUSIONS: These findings suggest that surgery may be safely delayed beyond 24 h from embolization without a higher risk of bleeding. In appropriately selected cohorts, embolization may not be needed preoperatively.
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Embolização Terapêutica , Neoplasias Renais , Neoplasias da Coluna Vertebral , Humanos , Neoplasias da Coluna Vertebral/cirurgia , Resultado do Tratamento , Estudos Retrospectivos , Neoplasias Renais/cirurgia , Perda Sanguínea Cirúrgica , Cuidados Pré-OperatóriosRESUMO
Recently, the utilization of biological agents in the green synthesis of nanoparticles has been given interest. In this study, silver nanoparticles were synthesized from an aqueous extract of macrofungus (mushroom), namely Phellinus adamantinus, in a dark room using 20 µL of silver nitrate. Biosynthesized silver nanoparticles were confirmed by analyzing them using a UV-Vis (ultraviolet-visible) spectrophotometer. The synthesized silver nanoparticles were optimized at different pH and temperatures with various dosages of AgNO3 (silver nitrate) and fungal extracts. The synthesized AgNPs (silver nanoparticles) were characterized using TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray) analyses, which confirmed the presence of silver nanoparticles. The size of the nanosilver particles was found to be 50 nm with higher stability. The mycosynthesized AgNPs showed effective antibacterial activity against strains of Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (E. coli and Pseudomonas aeruginosa) bacteria. The minimum inhibitory concentration (MIC) was found to be 3.125 µg/mL by MIC assay. The MTT assay (3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyl-2H-tetrazolium bromide) was performed to study cytotoxicity, and reduced cell viability was recorded at 100 µg/mL. Silver-Polygalacturonic acid-Polyvinyl alcohol ((Ag-PGA)-PVA) nanofiber was prepared using the electrospinning method. The in vitro wound scratch assay was demonstrated to study the wound-healing efficacy of the prepared nanofiber. The wound-healing efficacy of the AgNP-incorporated nanofiber was found to be 20% after 24 h. This study will lay a platform to establish a unique route to the development of a novel nanobiomaterial and its application in antibacterial and wound-healing therapy.
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Escherichia coli , Nanopartículas Metálicas , Prata , Nitrato de Prata , Antibacterianos/farmacologia , CorantesRESUMO
Patient-reported outcomes (PRO) are collected directly from the patient and have become increasingly utilized in the clinical setting and in clinical research. In musculoskeletal oncology patients, a number of patient-reported outcomes measures (PROM) have been developed and investigated to evaluate functional outcomes and health-related quality of life in these patients. With the growing evidence for PROM in musculoskeletal oncology patients, PROM should be considered for the clinical care of these patients.
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Neoplasias , Qualidade de Vida , Humanos , Oncologia , Medidas de Resultados Relatados pelo PacienteRESUMO
While single-cell sequencing technologies have revealed tissue heterogeneity, resolving mixed cellular libraries into cellular clones is essential for many pooled screens and clonal lineage tracing. Fluorescent proteins are limited in number, while DNA barcodes can only be read after cell lysis. To overcome these limitations, we used influenza virus hemagglutinins to engineer a genetically encoded cell-surface protein barcoding system. Using antibodies paired to hemagglutinins carrying combinations of escape mutations, we developed an exponential protein barcoding system which can label 128 clones using seven antibodies. This study provides a proof of principle for a strategy to create protein-level cell barcodes that can be used in vivo in mice to track clonal populations.
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Anticorpos Monoclonais/análise , Rastreamento de Células/métodos , Glicoproteínas de Hemaglutininação de Vírus da Influenza/análise , Animais , Rastreamento de Células/instrumentação , Feminino , Citometria de Fluxo/métodos , Células HEK293 , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Humanos , Melanoma/química , Melanoma/genética , Melanoma/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Orthomyxoviridae/química , Orthomyxoviridae/genética , Orthomyxoviridae/metabolismoRESUMO
OBJECTIVE: Radiotherapy is an important component of soft tissue sarcoma management. Radiation osteitis is a common radiographic finding identified in the setting of radiotherapy on magnetic resonance imaging (MRI). This study aims to identify the incidence of radiation osteitis in patients who received radiotherapy for soft tissue sarcoma and if a further workup, including a biopsy, was performed for concerning MRI findings. MATERIALS AND METHODS: Medical records of patients with soft tissue sarcoma who received radiotherapy from 2008 to 2020 were retrospectively reviewed. Patients with at least one MRI of the sarcoma site following radiotherapy and information regarding radiotherapy treatments were included. MRIs of these patients were reviewed for the presence of radiation osteitis by two musculoskeletal radiologists. The clinical course of these patients including biopsy for concerning MRI findings, local recurrence, and metastasis was recorded. RESULTS: Thirty soft tissue sarcoma patients who received radiation for soft tissue sarcoma were included. Radiation osteitis was present in 18 patients. The time to osteitis present on MRI following radiotherapy completion was a median of 4.5 months. Biopsy for concerning MRI findings was performed in eight patients, five for local recurrence, and three for regional osseous metastasis. Three patients had confirmed osseous metastases. CONCLUSION: Although radiation osteitis is often a benign imaging finding, it can be difficult to discern these lesions from potentially malignant sites of disease. We recommend multidisciplinary management of soft tissue sarcoma at sarcoma centers to appropriately identify benign from malignant lesions and decide the necessity of a biopsy.
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Osteíte , Sarcoma , Neoplasias de Tecidos Moles , Humanos , Osteíte/diagnóstico por imagem , Incidência , Estudos Retrospectivos , Sarcoma/diagnóstico por imagem , Sarcoma/radioterapia , Neoplasias de Tecidos Moles/diagnóstico por imagem , Neoplasias de Tecidos Moles/radioterapiaRESUMO
Newcastle disease virus (NDV) is an attractive candidate for oncolytic immunotherapy due to its ability to replicate in tumor cells and potentially to overcome the inherently immunosuppressive nature of the tumor microenvironment. The advent of checkpoint blockade immunotherapy over the past few years represents a paradigm shift in cancer therapy. However, the prevalence of severe immune-related adverse events with CTLA4 and PD1 pathway blockade in clinical studies, especially in combination therapy groups, is a cause for concern. Immunotherapies with cytokines have also been extensively explored, but they have been associated with adverse events in clinical trials. Oncolytic vectors engineered to express checkpoint blockade antibodies and cytokines could provide an avenue for reducing the clinical toxicity associated with systemic therapy by concentrating the immunomodulatory payload at the site of disease. In this study, we engineered six different recombinant viruses: NDVs expressing checkpoint inhibitors (rNDV-anti-PD1 and rNDV-anti-PDL1); superagonists (rNDV-anti-CD28); and immunocytokines, where the antibodies are fused to an immunostimulatory cytokine, such as interleukin 12 (IL-12) (rNDV-anti-CD28-murine IL-12 [mIL-12], rNDV-anti-PD1-mIL-12, and rNDV-anti-PDL1-mIL-12). These six engineered viruses induced tumor control and survival benefits in both highly aggressive unilateral and bilateral B16-F10 murine melanoma models, indicative of an abscopal effect. The data represent a strong proof of concept on which further clinical evaluation could build.IMPORTANCE Checkpoint inhibitor therapy has shown tremendous efficacy, but also frequent and often severe side effects-especially when multiple drugs of the class are used simultaneously. Similarly, many investigational immunotherapy agents, which have shown promise in animal models, have failed in clinical trials due to dose-limiting toxicity when administered systemically. This study utilized a murine melanoma model to evaluate the efficacy of intratumoral injections of recombinant NDVs engineered to express multiple immunotherapeutic proteins with well-documented side effects in humans. Our results indicate that intratumoral administration of these recombinant NDVs, particularly when combined with systemic CTLA4 checkpoint inhibition, exerts a robust effect in treated and nontreated tumors, indicative of a systemic antitumoral response. The intratumoral delivery of rNDVs expressing immunotherapeutic proteins may be an effective method of targeting the immune cell populations most relevant for antitumoral immunity and allowing us to restrict the use of systemic immunotherapy agents.
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Antineoplásicos/farmacologia , Citocinas/farmacologia , Imunoterapia/métodos , Doença de Newcastle/imunologia , Vírus da Doença de Newcastle/imunologia , Terapia Viral Oncolítica/métodos , Animais , Anticorpos Monoclonais Humanizados/farmacologia , Antígeno CTLA-4 , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Humanos , Melanoma , Camundongos , Camundongos Endogâmicos C57BL , Doença de Newcastle/virologia , Vírus Oncolíticos , Microambiente TumoralRESUMO
Dysregulation of the dynamic balance between cell proliferation and cell death leads to several malignancies including cancer. Biflavones are known to possess anti-proliferative activity against numerous cancer cell lines. The current study was undertaken to understand the mechanism of action of the biflavonoid (I-3,II-3)-biacacetin on MDA-MB-231. Biacacetin induces dose-dependent cell death in MDA-MB-231 cells from concentrations as low as 0.5 µM, which was further confirmed by an increase in sub-G1 cells. Furthermore, the cell death induced by biacacetin was found to be mitochondria-dependent, since cells devoid of mitochondria were viable in the presence of biacacetin even at the highest concentration tested (25 µM). Fluorescence studies clearly indicated nuclear changes and apoptotic body formation that are characteristic of apoptosis. These results were further corroborated by studies that demonstrate biacacetin to regulate several key markers of apoptosis like Caspase 3, p53, Bax, and poly-ADP-ribose polymerase-1. Furthermore, biacacetin did not induce cell death in normal macrophage cell line, RAW at concentrations up to 15 µM. In addition to MDA-MB-231 cells, biacacetin also induces apoptotic cell death in the highly chemo-resistant cell line, OVISE, where the cells stained positive for annexin. Biacacetin also induces cell death in the highly malignant fibrosarcoma cell line HT1080. Furthermore, biacacetin also induces significant cell death (50%) in 3D tumor spheroids, at a concentration of 25 µM. Taken together, these results provide an understanding of biacacetin-mediated cell death and thereby provides a strong basis for the use of such compounds as novel templates for anti-cancer therapeutics.
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Apoptose/efeitos dos fármacos , Neoplasias da Mama/patologia , Flavonas/farmacologia , Mitocôndrias/patologia , Neoplasias Ovarianas/patologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Feminino , Humanos , Mitocôndrias/efeitos dos fármacos , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Células Tumorais CultivadasRESUMO
Introduction: Nodular fasciitis is a rare, benign soft tissue lesion that can prove to be difficult to diagnose, especially when intra-articular. Case presentation: A 17-year-old female softball player presents with several year history of right knee pain and swelling initially attributed to patellar maltracking refractory to non-operative and operative management. Management and Outcomes: Initial pathology suggested tenosynovial giant cell tumor; however, further tissue diagnosis revealed nodular fasciitis, which was eventually resected. Conclusion: Intra-articular nodular fasciitis of the knee is rare and may easily be misdiagnosed due to its nonspecific clinical presentation. Careful histological examination can aid in diagnosis. Nodular fasciitis should be considered in the differential diagnoses for intra-articular lesions of the knee joint.
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CASE: A 40-year-old man was evaluated for a painful mass on his right calf, and a 36-year-old woman presented with a painless mass on her right foot. Final pathology revealed marked nuclear atypia and positivity for S100/SOX10 and AE1/AE3 confirming diagnoses of myoepithelial carcinoma. Both patients underwent surgical resection and are without evidence of local recurrence or metastatic disease at 1-year follow-up. CONCLUSION: Soft-tissue tumors presenting in the extremities warrant careful evaluation and timely histopathologic diagnosis. Myoepithelial carcinomas are rare, aggressive tumors with a propensity for local recurrence and metastasis. Treatment of these tumors should be discussed by a multidisciplinary tumor team.
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Carcinoma , Neoplasias de Tecidos Moles , Feminino , Masculino , Humanos , Adulto , Neoplasias de Tecidos Moles/diagnóstico por imagem , Neoplasias de Tecidos Moles/cirurgia , PéRESUMO
PURPOSE: Radiation induced changes in bone such as radiation osteitis are commonly identified on magnetic resonance imaging (MRI) in patients who receive radiotherapy for soft tissue sarcoma (STS) management. This study proposes a novel MRI scoring system to assess osseous lesions and predict potential for malignancy based on MRI score in STS patients who received radiotherapy. METHODS: The MRI score consisted of 3 parameters: morphology, signal intensity, and progression. Interobserver reliability between MRI scores were analyzed with Cohen's kappa coefficient. Receiver operating curve (ROC) analysis was performed to determine a predictive MRI score for malignancy. RESULTS: 156 MRI's from 30 STS patients who received radiotherapy were retrospectively reviewed. Two (6.7 %) patients developed regional osseous metastasis identified on MRI. The kappa coefficient of the scoring system was 0.785 demonstrating substantial interobserver agreement (p < 0.001). ROC analysis demonstrated that the optimal cut-off value for malignant lesion on MRI was 5.5 (area under the curve 0.998; p < 0.001). CONCLUSIONS: This novel MRI scoring system recommends lesions with a score of six and above to be biopsied to distinguish if malignancy is present. We believe this scoring system can be utilized by multidisciplinary care teams to guide clinical recommendations for patients with STS and MRI findings concerning for malignancy versus radiation induced changes.
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Introduction: Limb salvage surgery (LSS) is the preferred surgical treatment for bone sarcomas. Preoperatively, many patients receive chemotherapy and may develop neutropenia. No study has evaluated the effect of a low preoperative absolute neutrophil count (ANC) on postoperative outcomes following LSS. Methods: This was a retrospective review of 114 patients who underwent LSS for bone sarcoma from 2010 to 2020. Preoperative lab values were analyzed by logistic regression to identify the risk of developing surgical complications within 30 days, surgical site infection (SSI), and reoperation. Results: Three (2.6%) patients experienced a surgical complication within 30 days. Twelve (10.53%) patients experienced postoperative SSI. Twenty-nine (25.4%) required reoperation. Preoperative ANC was not a significant predictor of surgical complications within 30 days, SSI, or reoperation. The only independent predictor of worse overall survival was the presence of a pathologic fracture at the time of surgery. Conclusion: This is the first study to evaluate preoperative ANC on postoperative outcomes following LSS. We report no significant differences in surgical complications within 30 days, SSI, or reoperation with low preoperative ANC. Future studies with larger cohorts of neutropenic patients are needed to evaluate these outcomes, as our cohort had very few neutropenic patients due to selection bias.
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Background: Metastatic bone disease (MBD) commonly affects the hip and surgical intervention including total hip arthroplasty (THA) is often indicated to treat the joint and improve function. Patients with metastatic cancer often receive radiotherapy, and orthopaedic oncologists must consider surgical risks with operating on irradiated bone and soft tissue. We evaluated surgical outcomes and implant survival (IS) of titanium acetabular components and femoral components in patients treated for MBD in the setting of perioperative radiation. Methods: This was a retrospective review of patients who underwent THA for MBD at 3 institutions between 2017 and 2021. Outcomes included rates of reoperation, complications, IS, and overall survival. Results: Forty-six patients who received primary THA for MBD were included in the study. Twenty patients (43.5%) received perioperative radiation for MBD. Six postoperative complications including one superficial wound infection, 2 dislocations, 2 pathologic fractures, and one aseptic acetabular component loosening led to 5 reoperations. There were no significant differences in postoperative outcomes, reoperation after THA, and IS based on radiotherapy status. Conclusions: To our knowledge, this is the first paper evaluating primary THA outcomes and IS between patients who receive perioperative radiation for MBD to the hip and those who do not. As surgical management is a crucial part of the treatment in alleviating pain and disability in patients with MBD, we continue to recommend THA for patients who received radiation at the operative site.
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A 50-year-old man presented for evaluation of a periscapular mass. Biopsy suggested a low-grade chondrosarcoma; however, the resected specimen revealed a grade 2 chondrosarcoma with a low-grade dedifferentiated mesenchymal component. The mass multiply recurred as chondrosarcoma without a dedifferentiated component before the patient developed lung metastases of chondrosarcoma without a dedifferentiated component 11 years after the initial diagnosis and died of disease. This is one of the first reported cases of a dedifferentiated chondrosarcoma with low-grade dedifferentiated component. While overall prognosis may be better than in typical dedifferentiated chondrosarcoma, this tumor demonstrated numerous local recurrences as well as metastasis.
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Neoplasias Ósseas , Condrossarcoma , Masculino , Humanos , Pessoa de Meia-Idade , Neoplasias Ósseas/diagnóstico , Neoplasias Ósseas/patologia , Prognóstico , Biópsia , Doença Crônica , Condrossarcoma/diagnóstico , Condrossarcoma/cirurgia , Condrossarcoma/patologia , RecidivaRESUMO
BACKGROUND AND OBJECTIVES: Undifferentiated pleomorphic sarcoma (UPS) is a frequent subtype within the heterogeneous group of soft tissue sarcomas (STS). The use of radiotherapy (RT) has become an important component of a multimodal approach to treating STS. Key studies have demonstrated that the addition of RT improves rates of local control in STS, though the effect on overall survival (OS) is less clear. Furthermore, there is very limited and conflicting evidence regarding effect of RT on overall survival in UPS. The purposes of this investigation were to examine the association between RT and OS in UPS patients undergoing surgical resection and to determine independent prognostic indicators of OS in this patient population. METHODS: This was a retrospective review of patients who underwent surgical treatment for primary UPS from 1993 to 2021. Associations between RT and OS were analyzed with Kaplan-Meier curves and log-rank testing. Cox proportional hazards regression analysis was used to determine independent prognostic factors of OS. RESULTS: One hundred and fourteen patients who underwent surgical resection of primary UPS were included in the study. Ninety-six (84.2 %) patients received RT perioperatively. Use of RT was associated with improved OS on log-rank testing (hazard ratio (HR) 0.20; 95 % confidence interval (CI) 0.11-0.36; p < 0.001). On multivariate analysis, RT was an independent predictor of improved OS (HR 0.18; 95 % CI 0.09-0.39; p < 0.001) while metastasis at presentation (HR 4.82; 95 % CI 2.26-10.27; p < 0.001) and older age (HR 1.92; 95 % CI 1.20-3.36; p = 0.02) were predictive of decreased OS. Use of RT was not significantly associated with a lower rate of local recurrence in our cohort (p = 0.49). CONCLUSIONS: Use of RT in combination with surgery was an independent prognostic indicator of improved overall survival in UPS patients. Older age and metastasis at presentation were associated with worse overall survival. Based on this and other available studies, treatment for UPS should involve limb-sparing resection when feasible with RT to ensure optimal survival.
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Myxoid/round cell liposarcomas (MRCLPS) are a rare soft tissue sarcoma. We report the largest sarcoma in our institutional history. We discuss the patient's surgical management and treatment of the tumor and challenges given its dimensions. Several complications arose following primary resection that were managed by a multidisciplinary team. Although MRCLPS can vary in size, large MRCLPS must be treated cautiously given the potential for complications. Additionally, multidisciplinary treatment of MRCLPS is essential in diagnosing and treating these complex cases.
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Background/Objective: The hip is a common location for metastatic bone disease (MBD) and surgical intervention is often indicated to relieve pain and improve function. MBD of the hip is usually treated with hemiarthroplasty or with total hip arthroplasty if there are acetabular lesions. As treatment for metastatic disease evolves and patients may expect to live longer after diagnosis, further evaluation of the complications and functional outcomes associated with hip arthroplasty for MBD are necessary. Methods: This was a retrospective review of patients who underwent hip arthroplasty for MBD at a single institution between 2007 and 2021. Outcomes included rates of reoperation, complications, and overall survival. Results: Ninety-three cases in 91 patients were included. Total hip arthroplasty (THA) was performed in 52 cases (55.9%), hemiarthroplasty in 15 (16.1%), and complex arthroplasty, including proximal femur replacement or THA with complex acetabular reconstruction, was performed in 26 (28%). There were 11 reoperations in five patients and six dislocations. Median survival was 10.4 months and one-year overall survival was 53.3%. There was a significant increase in the proportion of patients who were able to ambulate independently (35.2% vs 17.6%; p=0.02) and a significant decrease in patients confined to a wheelchair (18.7% vs 3.3%; p=0.045) after surgery. Conclusions: Hip arthroplasty for MBD leads to relatively low rates of complications and reoperations in this population known to have high postoperative morbidity and mortality. Hip arthroplasty provides the majority of MBD patients with a durable reconstruction that exceeds their lifespan and enables them to return to an acceptable level of function.
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We present a case of a 58-year-old male who presented following 4 months of progressively worsening right upper extremity pain. Initial pathology demonstrated pleomorphic chondroblasts with increased mitotic activity indicating an intermediate grade (Grade 2) clear cell chondrosarcoma of the proximal humerus. Following surgical resection, the primary lesion demonstrated aggressive behavior and early metastasis to the cervical and thoracic spine. The patient unfortunately expired 30 months after initial presentation. Although clear cell chondrosarcoma has been historically regarded as low grade, we present a unique example of an aggressive clinical course of clear cell chondrosarcoma.
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Objectives: We sought to analyse the antibiotic susceptibility profiles and molecular epidemiology of MDR clinical Pseudomonas aeruginosa isolates from South India using non-MDR isolates as a reference. Methods: We established a comprehensive clinical strain library consisting of 58 isolates collected from patients across the South Indian state of Kerala from March 2017 to July 2019. The strains were subject to antibiotic susceptibility testing, modified carbapenem inactivation method assay for carbapenemase production, PCR sequencing, comparative sequence analysis and quantitative PCR of MDR determinants associated with antibiotic efflux pump systems, fluoroquinolone resistance and carbapenem resistance. We performed in silico modelling of MDR-specific SNPs. Results: Of our collection of South Indian P. aeruginosa clinical isolates, 74.1% were MDR and 55.8% were resistant to the entire panel of antibiotics tested. All MDR isolates were resistant to levofloxacin and 93% were resistant to meropenem. We identified seven distinct, MDR-specific mutations in nalD, three of which are novel. mexA was significantly overexpressed in strains that were resistant to the entire test antibiotic panel while gyrA and gyrB were overexpressed in MDR isolates. Mutations in fluoroquinolone determinants were significantly associated with MDR phenotype and a novel GyrA Y100C substitution was observed. Carbapenem resistance in MDR isolates was associated with loss-of-function mutations in oprD and high prevalence of NDM (blaNDM-1) within our sample. Conclusions: This study provides insight into MDR mechanisms adopted by P. aeruginosa clinical isolates, which may guide the potential development of therapeutic regimens to improve clinical outcomes.
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PIEZO1 is a mechanosensitive ion channel expressed in various organs, including but not limited to the brain, heart, lungs, kidneys, bone, and skin. PIEZO1 has been implicated in astrocyte, microglia, capillary, and oligodendrocyte signaling in the mammalian cortex. Using murine embryonic frontal cortex tissue, we examined the protein expression and functionality of PIEZO1 channels in cultured networks leveraging substrate-integrated microelectrode arrays (MEAs) with additional quantitative results from calcium imaging and whole-cell patch-clamp electrophysiology. MEA data show that the PIEZO1 agonist Yoda1 transiently enhances the mean firing rate (MFR) of single units, while the PIEZO1 antagonist GsMTx4 inhibits both spontaneous activity and Yoda1-induced increase in MFR in cortical networks. Furthermore, calcium imaging experiments revealed that Yoda1 significantly increased the frequency of calcium transients in cortical cells. Additionally, in voltage clamp experiments, Yoda1 exposure shifted the cellular reversal potential towards depolarized potentials consistent with the behavior of PIEZO1 as a non-specific cation-permeable channel. Our work demonstrates that murine frontal cortical neurons express functional PIEZO1 channels and quantifies the electrophysiological effects of channel activation in vitro. By quantifying the electrophysiological effects of PIEZO1 activation in vitro, our study establishes a foundation for future investigations into the role of PIEZO1 in neurological processes and potential therapeutic applications targeting mechanosensitive channels in various physiological contexts.
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Chronic implantation of intracortical microelectrode arrays (MEAs) capable of recording from individual neurons can be used for the development of brain-machine interfaces. However, these devices show reduced recording capabilities under chronic conditions due, at least in part, to the brain's foreign body response (FBR). This creates a need for MEAs that can minimize the FBR to possibly enable long-term recording. A potential approach to reduce the FBR is the use of MEAs with reduced cross-sectional geometries. Here, we fabricated 4-shank amorphous silicon carbide (a-SiC) MEAs and implanted them into the motor cortex of seven female Sprague-Dawley rats. Each a-SiC MEA shank was 8 µm thick by 20 µm wide and had sixteen sputtered iridium oxide film (SIROF) electrodes (4 per shank). A-SiC was chosen as the fabrication base for its high chemical stability, good electrical insulation properties, and amenability to thin film fabrication. Electrochemical analysis and neural recordings were performed weekly for 4 months. MEAs were characterized pre-implantation in buffered saline and in vivo using electrochemical impedance spectroscopy and cyclic voltammetry at 50 mV/s and 50,000 mV/s. Neural recordings were analyzed for single unit activity. At the end of the study, animals were sacrificed for immunohistochemical analysis. We observed statistically significant, but small, increases in 1 and 30 kHz impedance values and 50,000 mV/s charge storage capacity over the 16-week implantation period. Slow sweep 50 mV/s CV and 1 Hz impedance did not significantly change over time. Impedance values increased from 11.6 MΩ to 13.5 MΩ at 1 Hz, 1.2 MΩ-2.9 MΩ at 1 kHz, and 0.11 MΩ-0.13 MΩ at 30 kHz over 16 weeks. The median charge storage capacity of the implanted electrodes at 50 mV/s was 58.1 mC/cm2 on week 1 and 55.9 mC/cm2 on week 16, and at 50,000 mV/s, 4.27 mC/cm2 on week 1 and 5.93 mC/cm2 on week 16. Devices were able to record neural activity from 92% of all active channels at the beginning of the study, At the study endpoint, a-SiC devices were still recording single-unit activity on 51% of electrochemically active electrode channels. In addition, we observed that the signal-to-noise ratio experienced a small decline of -0.19 per week. We also classified observed units as fast and slow repolarizing based on the trough-to-peak time. Although the overall presence of single units declined, fast and slow repolarizing units declined at a similar rate. At recording electrode depth, immunohistochemistry showed minimal tissue response to the a-SiC devices, as indicated by statistically insignificant differences in activated glial cell response between implanted brains slices and contralateral sham slices at 150 µm away from the implant location, as evidenced by GFAP staining. NeuN staining revealed the presence of neuronal cell bodies close to the implantation site, again statistically not different from a contralateral sham slice. These results warrant further investigation of a-SiC MEAs for future long-term implantation neural recording studies.