Subcutaneous Implantation Research Articles

South African Parents' and Grandparents' Perspectives on the Acceptability of Implant Delivery of Treatment to Young Children with HIV.

Children living with HIV (CLWH) face unique challenges with adherence to antiretroviral therapy. In South Africa, just over a third of children receiving antiretroviral therapy are virally suppressed. Long-acting, subcutaneous implants may improve outcomes in CLWH compared to current daily oral dosing regimens. Qualitative in-depth interviews and focus group discussions (FGD) were conducted with 50 caregivers of CLHW in Johannesburg, South Africa. Interviews and FGDs were audio-recorded and transcribed. Data were coded and analyzed using Dedoose v9 software and a thematic approach. Caregivers had generally positive impressions of the pediatric HIV treatment implant. They emphasized the advantages of a long-acting and discreet treatment option for CLWH. Cited advantages were perceived to have widespread impact on CLWH, their caregivers, and other social dynamics. Caregivers raised some concerns or uncertainties about the potential efficacy, side effects and safety of the implant. Future clinical testing and outreach efforts may address such concerns and mitigate potential misinformation about implants. This study indicates the need to develop long-acting, discreet, safe, and efficacious HIV treatment options for young children.

Antithrombotic therapy and the risk of pocket hematoma after subcutaneous implantable cardioverter-defibrillator implantation

Abstract Introduction The PRAETORIAN trial, which randomized S-ICD versus TV-ICD in patients with a class I or IIa indication for ICD therapy, showed that clinically significant pocket hematomas were more frequent following S-ICD implantation. Many ICD recipients have comorbidities requiring anticoagulant (AC) and/or antiplatelet (AP) therapy, which increase the risk for hematoma formation post implantation. In contrast to TV-ICD implantation, little data exists regarding the optimal AC and AP strategy during S-ICD implantation to prevent pocket hematomas. Methods All patients who underwent de novo S-ICD implantations between February 2009 and January 2023 at our tertiary center were included. Data was collected retrospectively from electronic patient records. Clinically significant pocket hematomas were defined as an accumulation of blood at the pocket site within 30 days after S-ICD implantation, necessitating actions including applying a pressure bandage, surgical evacuation, drain insertion, a change in medication or an extended hospital stay or blood transfusion. Results A total of 348 patients were included of which 224 (64.4%) patients used antithrombotic therapy pre-implantation. Median age at implantation was 50 years (IQR: 36-61 years), 33.4% of the patients were female and the vast majority of implants were intermuscular (90.2%). Eighteen (5.2%) patients developed a clinically significant pocket hematoma. A total of 94 (27%) patients used AC therapy prior to the implantation of which 73 (21%) patients used a vitamin K antagonist (VKA). A total of 130 (37.4%) patients used AP therapy at baseline of which 49 (14.1%) patients were on dual AP therapy (DAPT). Continuation of VKA and continuation of DAPT with ticagrelor were independent predictors for pocket hematoma formation (p<0.001, and p<0.001 respectively). There were significantly more pocket hematomas in patients with continued VKA compared to patients with interrupted VKA (27.3 % (6/22) vs. 4.3% (2/47), respectively, p=0.011). Moreover, continuation of DAPT with ticagrelor was associated with significantly more pocket hematomas post implantation compared to continuation of DAPT with clopidogrel (4/12 vs 1/28, respectively, p=0.022). Conclusion This study showed that continuation of VKA during S-ICD implantation was associated with an increased risk of pocket hematoma formation compared to interruption of VKA. The continuation of DAPT with ticagrelor was an independent predictor of pocket hematoma formation and showed significantly more pocket hematomas compared to continuation of DAPT with clopidogrel. These findings support the need for specific peri-operative thrombotic therapy guidelines for S-ICD implantations to reduce the risk of pocket hematomas.

Bioprinting PDLSC-Laden Collagen Scaffolds for Periodontal Ligament Regeneration.

Periodontitis and severe trauma are major causes of damage to the periodontal ligament (PDL). Repairing the native conditions of the PDL is essential for the stability of the tissue and its interfaces. Bioprinting periodontal ligament stem cells (PDLSCs) is an interesting approach to guide the regeneration of PDL and interfacial integration. Herein, a collagen-based bioink mimicking the native extracellular matrix conditions and carrying PDLSCs was tested to guide the periodontal ligament organization. The bioink was tested at two different concentrations (10 and 15 mg/mL) and characterized by swelling and degradation, microstructural organization, and rheological properties. The biological properties were assessed after loading PDLSCs into bioinks for bioprinting. The characterization was performed through cell viability, alizarin red assay, and expression for ALP, COL1A1, RUNX2, and OCN. The in vivo biocompatibility of the PDLSC-laden bioinks was verified using subcutaneous implantation in mice. Later, the ability of the bioprinted PDLSC-laden bioinks on dental root fragments to form PDL was also investigated in vivo in mice for 4 and 10 weeks. The bioinks demonstrated typical shear-thinning behavior, a porous microstructure, and stable swelling and degradation characteristics. Both concentrations were printable and provided suitable conditions for a high cell survival, proliferation, and differentiation. PDLSC-laden bioinks demonstrated biocompatibility in vivo, and the bioprinted scaffolds on the root surface evidenced PDLSC alignment, organization, and PDLSC migration to the root surface. The versatility of collagen-based bioinks provides native ECM conditions for PDLSC proliferation, alignment, organization, and differentiation, with translational applications in bioprinting scaffolds for PDL regeneration.

Automated cardiac arrest DETECTion incorporated into a wristband: validation of a photoplethysmography algorithm in patients with spontaneous and induced cardiac arrest

Abstract Background Although survival from out-of-hospital cardiac arrest (OHCA) has improved, this does not apply to unwitnessed cases, as the arrest is often recognized too late. Automated cardiac arrest detection and alarming using a wristband is a promising technology to facilitate early assistance after cardiac arrest in a home setting. In the DETECT-1 study, a photoplethysmography(PPG) algorithm for circulatory arrest detection has been developed in patients with induced circulatory arrest. Purpose To assess the performance of the developed PPG algorithm for circulatory arrest detection in: 1) patients with spontaneous cardiac arrest; 2) subjects with induced circulatory arrest using blood pressure cuff inflation. Methods We selected patients with episodes of spontaneous cardiac arrest who participated in the DETECT-1 study and patients/healthy subjects with short-lasting induced circulatory arrest using blood pressure cuff inflations from the DETECT-1 and DETECT-2 studies. The DETECT-1 study included patients who underwent transcatheter aortic valve implantation (TAVI), subcutaneous ICD implantation, or ventricular tachycardia ablation. Included patients wore the PPG-wristband during the procedure. Continuous ECG and invasive blood pressure data were collected as reference standard. The DETECT-2 study included healthy volunteers who wore the PPG-wristband during physical exercise. Sensitivity for spontaneous and induced circulatory arrest and false positive alarms were assessed using the previously developed algorithm for circulatory arrest detection. All episodes were analyzed as individual events. Results A total of 39 individuals were included; nine patients with spontaneous cardiac arrests during TAVI and 20 subjects with 116 induced circulatory arrests. Of the patients with spontaneous cardiac arrest, two had ventricular fibrillation, five had pulseless electrical activity (figure), and two had asystole. Eight out of nine cardiac arrest events were detected by the circulatory arrest detection algorithm (sensitivity 89% [95% CI 51-99%]). Of the subjects with induced circulatory arrests, the PPG algorithm detected 114 induced circulatory arrests, yielding a sensitivity of 98% (95% CI 93-100%). In the entire group, there were no false positive alarms during 60 recording hours. Conclusions Automated cardiac arrest detection using a PPG-wristband is feasible with excellent sensitivity for both spontaneous and induced circulatory arrest. False positive alarms were absent in this controlled setting. Further study is warranted to assess algorithm performance in a larger sample of spontaneous cardiac arrests, and false positive alarms during daily life use. If available, automated cardiac arrest detection and alarming has the potential to markedly increase survival from OHCA in a home setting.Episode of spontaneous cardiac arrest

Automated cardiac arrest detection using a photoplethysmography wristband: algorithm performance in relation to sex, skin color type and arm hair density

Abstract Background While survival from witnessed out-of-hospital cardiac arrest (OHCA) has improved, this is not the case for unwitnessed cardiac arrest as the event goes unnoticed. Automated cardiac arrest detection and alerting through a wristband is considered a promising technique also facilitating early assistance for this large group. In the DETECT-1 study, a photoplethysmography(PPG) algorithm for circulatory arrest detection was developed in patients with induced circulatory arrest. However, patient characteristics, such as skin color and arm hair density, can influence the accuracy of the PPG signal. Thus, we performed further analyses to study the effect of patient characteristics on the algorithm’s performance. Purpose To assess the performance of the developed PPG algorithm for cardiac arrest detection in relation to sex, skin color type and arm hair density. Methods Patients who underwent short-lasting circulatory arrest induction during transcatheter aortic valve implantation, ventricular tachycardia ablation or subcutaneous ICD implantation wore a PPG wristband during the procedure. Continuous ECG and invasive blood pressure recordings served as reference standards. A PPG algorithm for circulatory arrest detection was developed. The algorithm’s performance was assessed in subgroups based on sex, skin color type (according to the Fitzpatrick scale), and arm hair density. The sensitivity for the detection of circulatory arrest and false positive alarms were compared between the different subgroups. Results In total, 151 patients were included in the current analysis. Analyzed data consisted of 159 hours of PPG data including 176 induced circulatory arrest events. The population consisted of 57 (38%) females and 94 (62%) males. The sensitivity for circulatory arrest detection was 100% in the female group vs. 98% in the male group (p=ns); false positive alarms occurred in 4 females and 9 males, resulting in a positive predictive value (PPV) of 94% and 92% (p=ns), respectively. Within the skin color subgroup analysis, 114 (75%) patients had skin color type I or II, and 37 (25%) patients had a skin color type III, IV, V or VI. There were no differences in sensitivity (p=ns) and PPV (p=ns) in the skin color subgroup (table 1). The population consisted of 106 (71%) patients with nil or sparse arm hair density, 43 (29%) patients with moderate or dense arm hair density, and 2 not reported. There were no differences in sensitivity (p=ns) and PPV (p=ns) within the arm hair density subgroup (table 1). Conclusions Automated cardiac arrest detection using a smartwatch is feasible and its accuracy is not affected by sex, skin color type or arm hair density in this study. Further study is needed to assess performance of the algorithm in a larger sample size and a more diverse study population. If proven to be effective, automated cardiac arrest detection has the potential to improve survival from OHCA.Sensitivity/PPV for arrest detection

Reduced Graphene Oxide-Substituted Nanohydroxyapatite: Rejuvenating Bone-Nerve Crosstalk with Electrical Cues in a Fragility Fracture Rat Model under Hyperglycemia.

Diabetes has currently acquired the status of epidemic worldwide, and among its various pathological consequences like retinopathy and nephropathy, bone fragility fractures from diabetic osteopathy occurs in later stages and is equally destructive. Chronic hyperglycemia culminates into deteriorating microvasculature and quality of bone, making it prone to fractures. Among these, hip fractures are most common, especially in older diabetic patients apart from underlying neuropathy. Our study is an attempt to ameliorate hip fragility fracture and nerve trauma with electrical stimulation as an interface in a chronic diabetic rat model. We have fabricated reduced graphene oxide-substituted hydroxyapatite as an electroactive bone substitute and incorporated it into chitosan gelatin cryogels. The in situ reduction of graphene oxide during sintering of hydroxyapatite imparts higher potential to the fabricated composite in dealing with problem at question. The cryogels depicted optimum in vitro biocompatibility and enhanced mineralization after ectopic subcutaneous implantation in rats. The therapeutic potency of composite cryogels was evaluated in a hip fracture model with compression to the sciatic nerve in diabetic rats, mimicking the severe clinical trauma. The presence of cryogels in the femoral neck canal coupled with electrical stimulation and biochemical factors significantly improved bone regeneration in diabetic rats as depicted with microcomputed tomography analysis and histology images. The application of electrical stimulation also ameliorated the nerve trauma observed with 70% improvement in electrophysiological parameters such as the compound muscle action potential with combinatorial therapy. We therefore report the successful implication of a multitarget therapy in a chronic diabetic rat model unraveling the bone-nerve crosstalk with electroactive smart cryogels.

Considerations of growth factor and material use in bone tissue engineering using biodegradable scaffolds in vitro and in vivo

Bone tissue engineering aims to harness materials to develop functional bone tissue to heal ‘critical-sized’ bone defects. This study examined a robust, coated poly(caprolactone) trimethacrylate (PCL-TMA) 3D-printable scaffold designed to augment bone formation. Following optimisation of the coatings, three bioactive coatings were examined, i) elastin-like polypeptide (ELP), ii) poly(ethyl acrylate) (PEA), fibronectin (FN) and bone morphogenetic protein-2 (BMP-2) applied sequentially (PEA/FN/BMP-2) and iii) both ELP and PEA/FN/BMP-2 coatings applied concurrently. The scaffold material was robust and showed biodegradability. The coatings demonstrated a significant (p < 0.05) osteogenic response in vitro in alkaline phosphatase gene upregulation and alkaline phosphatase production. The PCL-TMA scaffold and coatings supported angiogenesis and displayed excellent biocompatibility following evaluation on the chorioallantoic membrane assay. No significant (p < 0.05) heterotopic bone formed on the scaffolds within a murine subcutaneous implantation model, compared to the positive control of BMP-2 loaded collagen sponge following examination by micro-computed tomography or histology. The current studies demonstrate a range of innovative coated scaffold constructs with in vitro efficacy and clearly illustrate the importance of an appropriate in vivo environment to validate in vitro functionality prior to scale up and preclinical application.

Viscoelastic Hydrogel Modulates Phenotype of Macrophage-Derived Multinucleated Cells and Macrophage Differentiation in Foreign Body Reactions.

Biomaterial-induced macrophage-derived multinucleated cells (MNCs) are often observed at or near material implantation sites, yet their subtypes and roles in tissue repair and wound healing remain unclear. This study compares material-induced MNCs to cytokine-induced MNCs using both in vitro and in vivo models. 3D-embedded Raw264.7 cells and rat bone marrow-derived monocytes (BMDMs), with or without cytokines such as IL-4 and RANKL, were characterized for their MNC morphologies and subtypes via in situ immunocytochemistry and flow cytometry. Macrophage polarization and osteoclastic differentiation were assessed through NO production, arginase activity, and tartrate-resistant acid phosphatase levels. 3D matrix-induced MNCs expressed the same phenotypic heterogeneity as the IL-4 and RANK-treated ones. 3D matrix-induced MNCs displayed the same phenotypic heterogeneity as those treated with IL-4 and RANKL. A high viscoelastic matrix (1006.48 ± 92.29 Pa) induced larger populations of proinflammatory and osteoclast-like MNCs, whereas a low viscoelastic matrix (38.61 ± 7.56 Pa) supported active differentiation and gene expression across pro-, anti-inflammatory, and osteoclast-like macrophages. Matrix viscoelasticity also influenced the effects of IL-4 and RANKL on macrophage-derived MNC polarization. In an in vivo subcutaneous implantation model, medium to high viscoelastic matrices exhibited higher populations of CD86+ and RANK+ MNCs, while low viscoelastic matrices showed higher populations of CD206+ MNCs. These findings suggest that matrix viscoelasticity modulates macrophage differentiation and MNC phenotype, with low viscoelastic matrices potentially favoring anti-inflammatory MNCs and macrophage differentiation suitable for subcutaneous implantation.

Silk Composite-Based Multifunctional Pellets for Controlled Release.

Chronic wounds present significant clinical challenges due to the high risk of infections and persistent inflammation. While personalized treatments in point-of-care settings are crucial, they are limited by the complex fabrication techniques of the existing products. The calcium sulfate hemihydrate (CSH)-based drug delivery platform enables rapid fabrication but lacks antioxidant and antibacterial properties, essential to promote healing. To develop a multifunctional platform, a tannic acid (TA)-silk fibroin (SF) complex is engineered and incorporated as an additive in CSH cement. This cement is then cast into pellets to create silk/bioceramic-based composite drug delivery systems, designed for point-of-care use. Compared to neat CSH pellets, the composite pellets exhibit a 7.5-fold increase in antioxidant activity and prolonged antibacterial efficacy (up to 13 d). Moreover, the subcutaneous implantation of the pellets shows no hallmarks of local or systemic toxicity in a rodent model. The pellets are optimized in composition and fabrication to ease market translation. Clinically, the pellets have the potential to be further developed into products to place on wound beds or fill into bone cavities that are designed to deliver the intended therapeutic effect. The developed multifunctional system proves to be a promising solution for personalized treatment in point-of-care settings.

Glioblastoma multiforme recurrence on skin and subcutaneous tissue: a case report

Glioblastoma multiforme (GBM) is the most common malignant primary central nervous system (CNS) tumor. It presents an aggressive pattern, with a tendency for intracranial progression despite optimal treatment. On the other hand, metastases and manifestations outside the CNS are exceptional, and very few cases have been described. The authors submitted a case of a 48-year-old male diagnosed with a left parietooccipital GBM isocitrate dehydrogenase (IDH) wild-type, non-methylated O6-methylguanine-DNA methyltransferase (MGMT). Six months after surgical treatment, followed by a chemotherapy (CT) and radiotherapy scheme, he developed a few subcutaneous erythematous nodules within the surgical scar. A punch biopsy confirmed the histopathology of GBM. The CT scan showed concomitant intracranial progression. We ruled out systemic metastases. As the performance status was good [Karnofsky Performance Status 90 (KPS 90)] and the subcutaneous implants were growing rapidly, limiting the quality of life, we decided to perform palliative surgery to remove the implants. The result was good. Unfortunately, the patient worsened during the following week, after ruling out medical complications, we attributed the worsening to cerebral tumor swelling, revealed in the CT scan, as unresponsive to steroids. He passed away a few days later. Based on the analysis of our case, we intend to provide useful information for the approach to this peculiar manifestation of GBM.

Biocompatibility and Bone Regeneration by Shape Memory Polymer Scaffolds.

Biodegradable, shape memory polymer (SMP) scaffolds based on poly(ε-caprolactone) (PCL) offer unique advantages as a regenerative treatment strategy for critical-sized bone defects. In particular, a conformal fit may be achieved following exposure to warm saline, thereby improving osseointegration and regeneration. Advancing the clinical translation of these SMP scaffolds requires establishment of efficacy not only in non-loading models, but also load-bearing or load-sharing models. Thus, the present study evaluated the biocompatibility and bone regeneration potential of SMP scaffolds in a rabbit distal femoral condyle model. Two distinct SMP scaffold compositions were evaluated, a "PCL-only" scaffold formed from PCL-diacrylate (PCL-DA) and a semi-interpenetrating network (semi-IPN) formed from PCL-DA and poly(L-lactic acid) (PCL:PLLA). Semi-IPN PCL:PLLA scaffolds possess greater rigidity and faster rates of degradation versus PCL scaffolds. In vivo biocompatibility was assessed with a rat subcutaneous implantation model, whereas osseointegration was assessed with a 4 mm × 8 mm rabbit distal femoral condyle defect model. Both types of SMP scaffolds exhibited excellent biocompatibility marked by infiltration with fibrous tissue and a minimal inflammatory response. When implanted in the rabbit distal femur, both SMP scaffolds supported bone ingrowth. Collectively, these results demonstrate that the SMP scaffolds are biocompatible and integrate with adjacent host osseous tissues when implanted in vivo in a load-sharing environment. This study provides key proof-of-concept data necessary to proceed with large animal translational studies and clinical trials in human subjects.

Jawbone periosteum-derived cells with high osteogenic potential controlled by R-spondin 3.

The jawbone periosteum, the easily accessible tissue responding to bone repair, has been overlooked in the recent development of cell therapy for jawbone defect reconstruction. Therefore, this study aimed to elucidate the invitro and invivo biological characteristics of jawbone periosteum-derived cells (jb-PDCs). For this purpose, we harvested the jb-PDCs from 8-week-old C57BL/6 mice. The invitro cultured jb-PDCs (passages 1 and 3) contained skeletal stem/progenitor cells and exhibited clonogenicity and tri-lineage differentiation capacity. When implanted invivo, the jb-PDCs (passage 3) showed evident ectopic bone formation after 4-week subcutaneous implantation, and active contribution to repair the critical-size jawbone defects in mice. Molecular profiling suggested that R-spondin 3 was strongly associated with the superior invitro and invivo osteogenic potentials of jb-PDCs. Overall, our study highlights the significance of comprehending the biological characteristics of the jawbone periosteum, which could pave the way for innovative cell-based therapies for the reconstruction of jawbone defects.

Reactive oxygen species-responsive coating based on Ebselen: Antioxidation, pro-endothelialization and anti-hyperplasia for surface modification of cardiovascular stent

Atherosclerosis is often accompanied by inflammation and oxidative stress. Excessive reactive oxygen species (ROS) can damage the vascular endothelium, leading to endothelial dysfunction and reduced nitric oxide (NO) bioavailability. Further accumulation of ROS contributes to vascular cell damage, lipid peroxidation, and extracellular matrix deposition. Thus, clearing excess ROS and reshaping the oxidative microenvironment is essential for treating atherosclerosis (AS). In this study, Ebselen, which mimics glutathione peroxidase and possesses redox capabilities, was successfully synthesized. Subsequently, a multifunctional coating was designed using a combination of Ebselen and poly (trimethylene carbonate) (PTMC), capable of protecting cells from ROS-induced damage, promoting vascular endothelialization, and exhibiting anti-proliferative properties. The Ebselen-loaded coating effectively scavenges free radicals (with an elimination rate of 89 %), catalytically releases NO (0.96 × 10⁻¹⁰ to 1.26 × 10⁻¹⁰ mol/cm²/min), and sustainably delivers Ebselen to the lesion site through a redox cycle. Notably, this coating shows excellent hemocompatibility and cytocompatibility. Subcutaneous implantation results indicated that the fibrous capsule thickness of PTMC10 was the lowest, at just 47.7 % of that of PTMC. Therefore, the Ebselen-loaded coating presents promising applications in cardiovascular stents.

Development and Biocompatibility Assessment of Decellularized Porcine Uterine Extracellular Matrix-Derived Grafts.

Biomaterials derived from biological matrices have been widely investigated due to their great therapeutic potential in regenerative medicine, since they are able to induce cell proliferation, tissue remodeling, and angiogenesis in situ. In this context, highly vascularized and proliferative tissues, such as the uterine wall, present an interesting source to produce acellular matrices that can be used as bioactive materials to induce tissue regeneration. Therefore, this study aimed to establish an optimized protocol to generate decellularized uterine scaffolds (dUT), characterizing their structural, compositional, and biomechanical properties. In addition, in vitro performance and invivo biocompatibility were also evaluated to verify their potential applications for tissue repair. Results showed that the protocol was efficient to promote cell removal, and dUT general structure and extracellular matrix composition remained preserved compared with native tissue. In addition, the scaffolds were cytocompatible, allowing cell growth and survival. In terms of biocompatibility, the matrices did not induce any signs of immune rejection invivo in a model of subcutaneous implantation in immunocompetent rats, demonstrating an indication of tissue integration after 30 days of implantation. In summary, these findings suggest that dUT scaffolds could be explored as a biomaterial for regenerative purposes, which is beyond the studies in the reproductive field.

7355 A Case of High-Risk Thyroid Tumor Markers Found in Subcutaneous Thyroid Implants in a Patient with Benign Thyroid Pathology

Abstract Disclosure: J. Fedorko: None. S. Fatima: None. A.P. Amblee: None. C.A. Poku: None. Background: While fine needle aspiration (FNA) remains the primary diagnostic tool for thyroid malignancies, the utilization of molecular markers has become increasingly common in the workup of thyroid nodules. They play a useful role in distinguishing between malignant and benign pathology when cytology is indeterminate and in formulating treatment plans. The vast majority of research for these genetic markers is conducted in cases with thyroid malignancy. However, there have been numerous cases where these genetic markers were identified in benign thyroid tissue. Case: A 73-year-old male with left hemithyroidectomy (benign left nodule) presented 6 years later with new superficial neck nodules along the midline, left thyroid bed and R thyroid lobe. FNA of the right thyroid nodule was benign. Three months later the patient underwent an excision of the midline neck nodules which revealed thyroid tissue arranged in nests of fibrotic tissue without definite features of papillary thyroid carcinoma. Molecular analysis (Thyroseq) was positive for HRAS, E1F1AX and TERT mutations thus metastatic follicular carcinoma was suspected. The patient underwent complete thyroidectomy. Pathology revealed normal thyroid tissue and a diagnosis of thyroid neck implants was made. Given the benign pathology, the plan was for close follow-up with neck imaging every 6 months. Discussion: Thyroid tissue implants can rarely be caused by previous surgical interventions, especially partial thyroidectomy. There is literature documenting similar clinical cases in which subcutaneous thyroid implants are found in patients after undergoing total or subtotal thyroidectomy. In one case series, there were cases in which thyroid implants were discovered 26 years post-surgery, with most of the cases reporting benign pathology. Given our patient’s presentation and clinical history, the possibility remains that his subcutaneous tissue findings were caused by his prior partial thyroidectomy. A recent article reviewed 60 publications and &amp;gt;8000 patients for the prevalence of high-risk tumor markers (RAS mutation, RET/PTC, and PAX8/PPAR-gamma chromosomal rearrangements) in benign thyroid tissue. They concluded that prevalence findings were highly variable, warning providers to exercise caution when using these genetic markers to guide diagnosis and treatment decisions. Conclusion: While certain high-risk genetic tumor markers are increasingly used to help identify thyroid malignancies, it is important to keep in mind that these genetic markers are not exclusively found in cancerous tissue, and should not be used as the sole diagnostic tool for diagnosis and treatment. While it is imperative that metastatic disease is ruled out, it is essential to consider other pathologies when evaluating recurrent thyroid and neck masses in patients with a history of benign thyroid lesions. Presentation: 6/3/2024

8123 Identification Of Glutamine Metabolism As A Druggable Therapeutic Vulnerability For Adrenocortical Carcinoma

Abstract Disclosure: V. Chortis: None. C. Yao: None. C. Ribeiro: None. L. Kelley: None. L. Nagano: None. M. Berber: None. S. Raveenthiraraj: None. P. Vendramini: None. K. Kiseljak-Vassiliades: None. D.L. Carlone: None. M.C. Haigis: None. K.S. Borges: None. D.T. Breault: None. Dysregulation of cellular metabolism is a hallmark feature of cancer that can be targeted therapeutically but remains underexplored in adrenocortical carcinoma (ACC), despite the urgent need for improved treatments. We employed a recently developed transgenic mouse model of ACC (BPCre), driven by the two most common mutations in human ACC (β-catenin gain-of-function and p53 loss-of-function), aiming to characterize in vivo ACC metabolism at a tissue level and to identify metabolic vulnerabilities. We employed metabolomics (liquid chromatography-mass spectrometry) and transcriptomics (bulk RNA-seq) to compare tissue metabolism in spontaneous BPCre tumors with control adrenals. Polar metabolites were analyzed using a library that provides a representative cross-section of major carbon and nitrogen-handling pathways. We identified widespread dysregulation of tumor metabolism (64/175 metabolites significantly dysregulated, FDR&amp;lt;0.05), with the most significantly dysregulated pathways including purine and pyrimidine metabolism, proline and glutamate metabolism, glycolysis, and the pentose phosphate pathway (FDR&amp;lt;0.05). Orthogonal analysis by RNA-seq revealed congruent metabolic pathway alterations. Comparison of the most significantly dysregulated pathways between BPCre mouse tumors and human ACC using publicly accessible human transcriptomic datasets (TCGA and GTEx) revealed extensive overlap. Given the prominent dysregulation of several glutamine (Gln)-dependent metabolic pathways in mouse and human ACC, we hypothesized that Gln catabolism is likely to represent a targetable metabolic vulnerability in ACC. Pharmacological targeting of Gln metabolism using the Gln antagonist 6-Diazo-5-Oxo-L-Norleucine (L-DON) induced marked cytotoxicity in two cell lines derived from BPCre tumors and three human ACC cell lines (NCI-H295R, CU-ACC1-2), as assessed by cell viability and clonogenic assays. Remarkably, this effect was rescued only by nucleoside supplementation, suggesting that Gln’s contribution to de novo purine and pyrimidine biosynthesis is the critical metabolic dependency in ACC cells. Treatment with the L-DON pro-drug JHU-083, in vivo, led to marked growth inhibition of subcutaneous mouse ACC tumor implants in both immunocompetent and immunodeficient mice. As expected, tissue metabolomics of JHU-083-treated tumors confirmed extensive depletion of purine metabolites. Tumor immunophenotyping by flow cytometry revealed significantly increased infiltration with Natural Killer cells, likely potentiating the anti-tumor effect of glutamine antagonism in immunocompetent mice. JHU-083 was also effective against human NCI-H295R xenografts, in vivo. This work reveals important new insights into ACC metabolism and provides pre-clinical evidence supporting Gln antagonism as a new metabolic treatment approach for ACC. Presentation: 6/2/2024

A hybrid construct with tailored 3D structure for directing pre-vascularization in engineered tissues

Hybrid 3D constructs combining different structural components afford unique opportunities to engineer functional tissues. Creating functional microvascular networks within these constructs is crucial for promoting integration with host vessels and ensuring successful engraftment. Here, we present a hybrid 3D system in which poly (ethylene oxide terephthalate)/poly (butylene terephthalate) fibrous scaffolds are combined with pectin hydrogels to provide internal topography and guide the formation of microvascular beds. The sequence/method of seeding human endothelial cells (EC) and mesenchymal stromal cells (MSC) into the system had a significant impact on microvessel formation. Optimal results were obtained when EC were directly seeded onto the fibrous scaffold, followed by the addition of hydrogel-embedded MSC. This approach facilitated the development of highly oriented microvascular networks along the fibers. These networks were lumenized, supported by a basement membrane, and stabilized by pericyte-like cells, persisting for at least 28 days in vitro. Furthermore, culture under pro-angiogenic and osteoinductive conditions induced MSC osteogenic differentiation without impairing microvessel formation. Upon subcutaneous implantation in mice, the pre-vascularized constructs were infiltrated by host vessels, and human microvessels were still present after 2 weeks. Overall, the proposed hybrid 3D system, combined with an optimized cell-seeding protocol, offers an effective approach for directing the formation of robust and geometrically oriented microvessels, making it promising for tissue engineering applications.

Melanoma-inhibiting activity promotes the migration and odontoblastic differentiation of stem cells of apical papilla

ObjectiveMelanoma Inhibitory Activity (MIA) has been predominantly studied in the context of melanoma and cartilage development. However, its role in dental pulp development and stem cell behavior remains largely unexplored. This study investigates the expression pattern of MIA in dental pulp tissues and its potential role in the proliferation, migration, and odontoblastic differentiation of stem cells from the apical papilla (SCAPs). Design:MIA expression in human pulp tissue was demonstrated by immunohistochemistry. SCAPs were cultured in normal and mineralization induction media, with MIA levels monitored via RT-qPCR and Western blot. Cell proliferation was evaluated using the CCK8 assay, while transwell and cell scratch assays were conducted to examine cell migration. The effect of MIA on odontoblastic differentiation was examined by qRT-PCR, Alkaline phosphatase activity assay, and Western blot. siRNA was used to knock down MIA to investigate its effect. A mouse subcutaneous implantation model was used to assess whether MIA promotes odontoblastic differentiation in vivo. Results:MIA expression was observed in the papilla and odontoblasts layer of the developing pulp. In vitro, MIA expression increased during SCAPs differentiation and was found to significantly enhance migration, and odontoblastic differentiation but not proliferation. Gene knockdown experiments confirmed MIA’s pivotal role in promoting SCAPs migration and differentiation. In vivo, MIA facilitated the formation of dentin-like structures and enhanced pulp-dentin complex regeneration. Conclusion:MIA plays a crucial role in SCAPs’ migration and differentiation, suggesting its potential application in pulp-dentin regeneration therapies. Further studies are required to fully elucidate the underlying mechanisms.

Folic acid modified silver nanoparticles promote endothelialization and inhibit calcification of decellularized heart valves by immunomodulation with anti-bacteria property

Xenogeneic decellularized heart valves (DHVs) have become one of the most commonly used scaffolds for tissue engineered heart valves (TEHVs) due to extensive resources and possessing the distinct three-layer structure similar to native heart valves. However, DHVs as scaffolds face the shortages such as poor mechanical properties, proneness to thrombosis and calcification, difficulty in endothelialization and chronic inflammatory responses etc., which limit their applications in clinic. In this work, we constructed a novel TEHV with immunomodulatory functions by loading folic acid modified silver nanoparticles (FS NPs) on DHVs to overcome these issues. The FS NPs preferentially targeted M1 macrophages and reduced their intracellular H2O2 level, resulting in polarizing them into M2 phenotype. The increased M2 macrophages facilitated to eliminate inflammation, recruit endothelial cells, and promote their proliferation and endothelialization by secreting relative factors. We founded that FS NPs with the size of 80 nm modified DHVs (FSD-80) performed optimally on cytocompatibility and regulating macrophage phenotype ability in vitro. In addition, the FSD-80 had excellent mechanical properties, hemocompatibility and anti-bacteria property. The results of the subcutaneous implantation in rats revealed that the FSD-80 also had good performance in regulating macrophage phenotype, promoting endothelialization, remolding the extracellular matrix and anti-calcification in vivo. Therefore, FS NPs-loaded DHVs possess immunomodulatory functions, which is a feasible and promising strategy for constructing TEHVs with excellent comprehensive performance.

A facile nanopattern modification of silk fibroin electrospun scaffold and corresponding impact on cell proliferation and osteogenesis

Abstract As a well-known natural protein biomaterial, silk fibroin (SF) has shown broad application prospects in typical biomedical fields. However, the mostly used SF from Bombyx mori silkworm lacks specific cell adhesion sites and other bioactive peptide sequences, and there is still significant room for further improvement of their biological functions. Therefore, it is crucial to develop a facile and effective modification strategy for this widely researched biomaterial. In this study, the SF electrospun scaffold has been chosen as a typical SF biomaterial, and air plasma etching has been adopted as a facile nanopattern modification strategy to promote its biological functions. Results demonstrated that the plasma etching could feasibly and effectively create nano-island-like patterns on the complex surface of SF scaffolds, and the detailed nanopattern features could be easily regulated by adjusting the etching time. In addition, the mesenchymal stem cell responses have illustrated that the nanopattern modification could significantly regulate corresponding cell behaviors. Compared with the non-etched scaffold, the 10 min-etched scaffold (10E scaffold) significantly promoted stem cell proliferation and osteogenic differentiation. Moreover, 10E scaffold has also been confirmed to effectively accelerate vascularization and ectopic osteogenesis in vivo using a rat subcutaneous implantation model. However, the mentioned promoting effects would be weakened or even counteracted with the increase of etching time. In conclusion, this facile modification strategy demonstrated great application potential for promoting cell proliferation and differentiation. Thus, it provided useful guidance to develop excellent SF-based scaffolds suitable for bone and other tissue engineering.