Background Head and neck cancer (HNC) is one of the most common cancers, associated with a huge m... more Background Head and neck cancer (HNC) is one of the most common cancers, associated with a huge mortality and morbidity. In order to improve patient outcomes, more efficient and targeted therapies are essential. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) express tumour homing capacity, which could be exploited to target anti-cancer drug delivery to the tumour region and reduce adverse side-effects. Nevertheless, dental pulp stromal cells (DPSCs), an MSC-like population present in teeth, could offer important clinical benefits because of their easy isolation and superior proliferation compared to BM-MSCs. Therefore, we aimed to elucidate the tumour homing and safe usage of DPSCs to treat HNC. Methods The in vivo survival as well as the effect of intratumourally administered DPSCs on tumour aggressiveness was tested in a HNC xenograft mouse model by using bioluminescence imaging (BLI), (immuno)histology and qRT-PCR. Furthermore, the in vitro and in vivo tumour homing capacity of DPSCs towards a HNC cell line were evaluated by a transwell migration assay and BLI, respectively. Results Intratumourally injected DPSCs survived for at least two weeks in the tumour micro-environment and had no significant influence on tumour morphology, growth, angiogenesis and epithelial-to-mesenchymal transition. In addition, DPSCs migrated towards tumour cells in vitro, which could not be confirmed after their in vivo intravenous, intraperitoneal or peritumoural injection under the tested experimental conditions. Conclusions Our research suggests that intratumourally delivered DPSCs might be used as safe factories for the continuous delivery of anti-cancer drugs in HNC. Nevertheless, further optimization as well as efficacy studies are necessary to understand and improve in vivo tumour homing and determine the optimal experimental set-up of stem cell-based cancer therapies, including dosing and timing.
Several clinical and experimental studies have demonstrated that advanced glycation end products ... more Several clinical and experimental studies have demonstrated that advanced glycation end products (AGEs) are associated with adverse cardiac outcome. Growing evidence shows that high molecular weight AGEs (HMW-AGEs) might be as important as the characterized low molecular weight AGEs. To date, the role of HMW-AGEs in the pathogenesis of cardiac remodeling remains unknown. In this study, we investigated whether HMW-AGEs are involved in cardiac dysfunction. Healthy rats were daily ip injected with 20mg/kg BSA-derived HMW-AGEs or, as a control, unmodified BSA, during 6weeks. Cardiac function was assessed with echocardiography. Plasma levels of glucose, AGEs and soluble RAGE (sRAGE) were measured. AGEs, RAGE and lysyl oxidase (LOX) expression were determined by western blot. After 6weeks, animals displayed a sustained increase in circulating total AGEs without hyperglycemia. HMW-AGEs injections induced cardiac dysfunction characterized by wall hypertrophy, increased heart sphericity, reduced strain and strain rate with preserved ejection fraction. Plasma sRAGE levels were significantly higher compared to control and correlated significantly with decreased strain. RAGE expression, TNF-α and IL-6 remained unchanged. Finally, HMW-AGEs induced prominent cardiac fibrosis associated with an increased LOX expression. Our data demonstrate that rather than via a specific activation of RAGE, the deleterious effects of HMW-AGEs are likely mediated via an increased collagen cross-linking responsible for the observed cardiac stiffness. Additionally, we show that in the setting of elevated HMW-AGEs, increased sRAGE levels are markers of altered cardiac function.
The centre of the tooth harbours the dental pulp, a soft connective tissue which plays a pivotal ... more The centre of the tooth harbours the dental pulp, a soft connective tissue which plays a pivotal role in the homeostasis of tooth vitality and health. This tissue is highly vascularised and responsible for nutrient supply and waste removal. In addition, it contains an immune system as a defence against invading bacteria. Nevertheless, penetration of cariogenic bacteria can lead to necrosis of the tissue and blood vessels. Although current endodontic practice aims to sustain pulp vitality and tooth viability, the limitations associated with these procedures emphasise the need for alternative treatment protocols. The ideal therapeutic solution would be to regenerate a fully functional pulp tissue. As blood vessel formation is key in tissue regeneration, this process is the main focus of recent endodontic studies. This chapter first discusses the fundamental concepts of blood vessel development. Next, the morphology, ontogenesis and regulation of pulpal blood vessels are described. Finally, an overview on the preclinical advancements made to improve pulpal vascularisation is given: herein cell-free therapies using proteins and biodegradable scaffolds as well as the application of stem cells are discussed.
Although regenerative endodontic procedures have yielded an impressive body of favorable outcomes... more Although regenerative endodontic procedures have yielded an impressive body of favorable outcomes, the treatment of necrotic immature permanent teeth in particular remains to be a challenge. Recent advances in dental stem cell research have gained increasing insight in their regenerative potential and prospective use in the formation of viable dental tissues. Numerous studies already reported successful dental pulp regeneration following application of dental pulp stem cells, stem cells from the apical papilla or dental follicle precursor cells in different in vivo models. Next to responsive cells, dental tissue engineering also requires the support of an appropriate scaffold material, ranging from naturally occurring polymers to treated dentin matrix components. However, the routine use and banking of dental stem cells still holds some major challenges, such as culture-associated differences, patient-related variability and the effects of culture medium additives. Only in-depth evaluation of these problems and the implementation of standardized models and protocols will effectively lead to better alternatives for patients who no longer benefit from current treatment protocols.
bioRxiv (Cold Spring Harbor Laboratory), Dec 23, 2022
Macrophages play major roles in the pathophysiology of various neurological disorders, being invo... more Macrophages play major roles in the pathophysiology of various neurological disorders, being involved in seemingly opposing processes such as lesion progression and resolution. Yet, the molecular mechanisms that drive their harmful and benign effector functions remain poorly understood. Here, we demonstrate that extracellular vesicles (EVs) secreted by repair-associated macrophages (RAMs) enhance remyelination ex vivo and in vivo by promoting the differentiation of oligodendrocyte precursor cells (OPCs). Guided by lipidomic analysis and applying cholesterol depletion and enrichment strategies, we find that EVs released by RAMs show markedly elevated cholesterol levels and that cholestserol abundance controls their reparative impact on OPC maturation and remyelination. Mechanistically, EV-associated cholesterol was found to promote OPC differentiation through direct membrane fusion. Collectively, our findings highlight that EVs are essential for cholesterol trafficking in the brain and that changes in cholesterol abundance dictate the reparative impact of EVs released by macrophages in the brain, potentially having broad implications for therapeutic strategies aimed at promoting repair in neurodegenerative disorders.
Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been... more Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been admitted to the intensive care unit (ICU) often face months of physical disability after discharge. To optimize recovery, it is important to understand the role of musculoskeletal alterations in critically ill patients infected with SARS-CoV-2. The main aim of the present study was to describe the presence and morphology of nemaline bodies found in the skeletal muscle tissue from critically ill patients infected with SARS-CoV-2. In n = 7 patients infected with SARS-CoV-2, ultrastructural characteristics of vastus lateralis muscle obtained on days 1–3 and days 5–8 following ICU admission were investigated in more detail with electron microscopy. Those muscle biopsies consistently showed variable degrees of myofiber necrosis and myofibrillar disorganization. In 4/7 (57%) patients on days 5–8, the Z-line material accumulated into nemaline bodies with a typical lattice-like appearance at hi...
Background: Early detection of marginal bone loss is vital for treatment planning and prognosis o... more Background: Early detection of marginal bone loss is vital for treatment planning and prognosis of teeth and implant. This study was conducted to assess diagnostic accuracy of CBCT compared to intra-oral (IO) radiography for detection, classi cation and measurement of peri-implant bone defects in an animal model. Methods: Fifty-four mandible blocks with implants were harvested from nine male health adult beagle dogs with acquisition of IO, CBCT and micro-CT images from all samples. Peri-implant bone defects from 16 samples were diagnosed using micro-CT and classi ed into 3 defect categories: dehiscence (n = 5), infrabony defect (n = 3) and crater-like defect (n = 8). Following training and calibration of the observers, they asked to detect location (mesial, distal, buccal, lingual) and shape of the defect (dehiscence, horizontal defect, vertical defect, carter-like defect) utilizing both IO and CBCT images. Both observers assessed defect depth and width on IO, CBCT and micro-CT images at each side of peri-implant bone defect via CT-analyzer software. Data were analyzed using SPSS software and a p value of < 0.05 was considered as statistically signi cant. Results: Overall, there was a high diagnostic accuracy for detection of bone defects with CBCT images (sensitivity: 100%/100%), while IO images showed a reduction in accuracy (sensitivity: 69%/63%). Similarly, diagnostic accuracy for defect classi cation was signi cantly higher for CBCT, whereas IO images were unable to correctly identify vestibular dehiscence, with incorrect assessment of half of the infrabony defects. For accuracy of measuring defect depth and width, a higher correlation was observed between CBCT and gold standard micro-CT (r = 0.91, 95% CI: 0.86-0.94), whereas a lower correlation was seen for IO images (r = 0.82, 95%CI: 0.67-0.91). Conclusions: The diagnostic accuracy and reliability of CBCT was found to be superior to IO imaging for the detection, classi cation and measurement of peri-implant bone defects. The application of CBCT adds substantial information related to the peri-implant bone defect diagnosis and decision-making which cannot be achieved with conventional IO imaging.
The transplantation of pancreatic islets (PIs) containing insulin producing beta cells is conside... more The transplantation of pancreatic islets (PIs) containing insulin producing beta cells is considered an alternative approach for the treatment of type 1 diabetes mellitus (T1DM) [1]. Currently, different transplantation sites are assessed in clinical trials to improve outcome [2, 3]. To better monitor and validate the success of transplantation, it is desirable to monitor the location of engrafted islets noninvasively [4]. In vivo MR imaging of transplanted islets is one of the most suitable cell tracking methods, however, this requires labeling of the islets with a suitable contrast agent prior to transplantation [5-8]. In this study, we have tested the feasibility of cationic magnetoliposomes (MLs) compared to commercial contrast agents (Endorem and Resovist) by labeling insulinoma cells (INS1E) and freshly isolated rat PIs. It was possible to incorporate MR detectable amounts of MLs in a much shorter time (2 hours) without addition of transfection agents when compared to Endorem and Resovist. MLs did not show negative effects on the PIs viability and functional parameters in vitro. Further, labeled islets were transplanted in the renal sub-capsular region of healthy mice. Hypointense contrast in MR images due to the labeled PIs was detected in vivo upon transplantation. However MRI based detection was not possible when islets were labeled with Endorem and Resovist alone, but after addition of the transfection agent Poly-L-Lysin (PLL). The findings of this study indicate that MLs provides a satisfactory means to image pancreatic islets and have no deleterious effect on their function, which is promising for future pre-clinical and clinical studies involving the assessment of islet transplantation. Magnetoliposomes (MLs) are built up of nm-sized magnetite (Fe3O4) core, in which the original stabilizing lauric acid coat is first replaced by a phospholipid bilayer during incubation and dialysis of the fatty acid coated particle with performed small unilamellar phospholipid vesicles. Mechanistically, it has been proven that the process of ML formation is controlled by spontaneous transfer of phospholipids according to the so-called aqueous transfer model [9,10]. As MLs can be categorized as ‘ultrasmall superparamagnetic iron oxides’ (commonly designated as USPIO ́s), a high gradient magnetic field (HGM) is needed to withdraw the MLs from the incubation mixture. For a 14 nmdiameter iron oxide core covered with an intact phospholipid bilayer, typically, a phospholipid/Fe3O4 (mmol/g) ratio between 0.7 and 0.8 is calculated. The ligand exchange reaction can also be used to incorporate fluorophores (fluorescent labels for microscopic validation) or targeting molecules (small molecules targeting the GLUT2, monoclonal antibodies and potentially nanobodies) to the MLs double-layer.
Mandibular repositioning devices (MRDs) increase the patency of the upper airway by repositioning... more Mandibular repositioning devices (MRDs) increase the patency of the upper airway by repositioning the mandible forward, resulting in displacement of the oropharyngeal tissues preventing upper airway collapsibility. Mandibular anterior repositioning is counteracted by muscle force from the temporalis muscle. A 39-year-old man had an osteolytic lesion with fracture of the coronoid process of the mandible secondary to wearing a MRD for sleep apnea. Continuous stress generated on the coronoid process temporalis muscle resulted in osteolysis and fracture of the coronoid process on the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s right side, resulting in swelling and limited ability to open his mouth. The patient was managed with intravenous antibiotics to control the osteomyelitis and surgical debridement, with removal of the coronoid process of the mandible. It is unclear why the fracture only occurred on the right side. Pathologic fracture of the coronoid process due to chronic stress and secondary osteomyelitis is a rare severe complication of treatment for obstructive sleep apnea syndrome with a MRD.
Journal of Oral and Maxillofacial Surgery, Oct 1, 2018
Trigeminal neuralgia is characterized by unilateral pain in the region supplied by the sensory di... more Trigeminal neuralgia is characterized by unilateral pain in the region supplied by the sensory distribution of the fifth cranial nerve. Pharmacologic therapy is an adequate initial treatment option in 75% of patients. When the Jannetta surgical operation is not available or not indicated and when conservative treatment fails to relieve the pain or the medication has to be discontinued because of side effects, one of the remaining surgical options is cryosurgery in the peripherally distributed nerves that emanate from the trigeminal nerve. This technical note describes a perioperative method for exposing and mobilizing the inferior alveolar nerve (IAN) from its bony canal. This approach provided easy access to infratemporal fossa structures during cryotherapy. This technique represented a further development of the technique previously described by the authors. This method ensured direct visualization of the IAN and wide access to theinfratemporal fossa during IAN cryotherapy.
British Journal of Oral & Maxillofacial Surgery, Oct 1, 2020
Please cite this article in press as: da Costa Senior O, et al. Long-term neurosensory disturbanc... more Please cite this article in press as: da Costa Senior O, et al. Long-term neurosensory disturbances after modified sagittal split osteotomy.
International Journal of Oral Science, Jul 14, 2017
The main goal of this study was to introduce a novel three-dimensional procedure to objectively q... more The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography (MSCT) and postoperative cone-beam computed tomography (CBCT) images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients (11 female and 9 male) who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter-and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical setup , were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant (Po0.05) mean bone volume decrease of 26.4% ± 11.4% (502.9 mm 3 ± 268.1 mm 3). No significant effects of side, sex or age were found. Good to excellent (ICC40.6) intra-and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel (0.4 mm) for MSCT (0.3 mm ± 0.2 mm) and CBCT (0.4 mm ± 0.3 mm), thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.
Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in child... more Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in children and adolescents. The aim of this study was to evaluate the outcome of the cone-beam computed tomographic (CBCT)-guided TAT compared to the conventional TAT protocol and to assess the 3-dimensional (3D) patterns of healing after CBCT-guided TAT (secondary aim). This study included 100 autotransplanted teeth in 88 patients. Each experimental group consisted of 50 transplants in 44 patients (31 males and 19 females). The mean (SD) age at the time of surgery was 10.7 (1.1) y for the CBCT-guided group. This was 10.6 (1.3) y for the conventional group. The mean (SD) follow-up period was 4.5 (3.1) y (range, 1.1 to 10.4 y). Overall survival rate for the CBCT-guided TAT was 92% with a success rate of 86% compared to an 84% survival rate and a 78% success rate for the conventional group (P > 0.005). The following measurements were extracted from the 3D analysis: root hard tissue volume (RV), root length (RL), apical foramen area (AFA), and mean and maximum dentin wall thickness (DWT). Overall, the mean (SD) percentage of tissue change was as follows: RV gain by 65.8% (34.6%), RL gain by 37.3% (31.5%), AFA reduction by 91.1% (14.9%), mean DWT increase by 107.9% (67.7%), and maximum DWT increase by 26.5% (40.1%). Principal component analysis (PCA) identified the mean DWT, RV, and maximum DWT as the parameters best describing the tissue change after TAT. Cluster analysis applied to the variables chosen by the PCA classified the CBCT group into 4 distinct clusters (C1 = 37.2%, C2 = 17.1%, C3 = 28.6%, C4 = 17.1%), revealing different patterns of tissue healing after TAT. The CBCT-guided approach increased the predictability of the treatment. The 3D analysis provided insights into the patterns of healing. CBCT-guided TAT could be adopted as an alternative for the conventional approach. (Clinical trial center and ethical board University Hospitals, KU Leuven: S55287; ClinicalTrials.gov Identifier: NCT02464202
bioRxiv (Cold Spring Harbor Laboratory), Apr 2, 2023
Duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A) and is known to disrupt t... more Duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A) and is known to disrupt the lipid metabolism in myelinating Schwann cells by unknown mechanisms. By using two CMT1A mouse models overexpressing human PMP22, we discovered that PMP22 dose-dependently downregulates genes that are involved in lipid and cholesterol metabolism. Lipidomic analysis on CMT1A mouse sciatic nerves confirmed lipid metabolic abnormalities primarily associated with cholesterol and sphingolipids. We observed similar lipidomic profiles and downregulation of genes associated with lipid metabolism in human CMT1A patient induced pluripotent stem cell-derived Schwann cell precursors (iPSC-SCPs). We confirmed these findings by demonstrating altered lipid raft dynamics and plasma membrane fluidity in CMT1A iPSC-SCPs. Additionally, we identified impaired cholesterol incorporation in the plasma membrane due to altered lipid storage homeostasis in CMT1A iPSC-SCPs, which could be modulated by changing the lipid composition of the cell culture medium. These findings suggest that PMP22 plays a role in regulating the lipid composition of the plasma membrane and lipid storage homeostasis. Targeting lipid metabolism may hold promise as a potential treatment for CMT1A patients.
Background Head and neck cancer (HNC) is one of the most common cancers, associated with a huge m... more Background Head and neck cancer (HNC) is one of the most common cancers, associated with a huge mortality and morbidity. In order to improve patient outcomes, more efficient and targeted therapies are essential. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) express tumour homing capacity, which could be exploited to target anti-cancer drug delivery to the tumour region and reduce adverse side-effects. Nevertheless, dental pulp stromal cells (DPSCs), an MSC-like population present in teeth, could offer important clinical benefits because of their easy isolation and superior proliferation compared to BM-MSCs. Therefore, we aimed to elucidate the tumour homing and safe usage of DPSCs to treat HNC. Methods The in vivo survival as well as the effect of intratumourally administered DPSCs on tumour aggressiveness was tested in a HNC xenograft mouse model by using bioluminescence imaging (BLI), (immuno)histology and qRT-PCR. Furthermore, the in vitro and in vivo tumour homing capacity of DPSCs towards a HNC cell line were evaluated by a transwell migration assay and BLI, respectively. Results Intratumourally injected DPSCs survived for at least two weeks in the tumour micro-environment and had no significant influence on tumour morphology, growth, angiogenesis and epithelial-to-mesenchymal transition. In addition, DPSCs migrated towards tumour cells in vitro, which could not be confirmed after their in vivo intravenous, intraperitoneal or peritumoural injection under the tested experimental conditions. Conclusions Our research suggests that intratumourally delivered DPSCs might be used as safe factories for the continuous delivery of anti-cancer drugs in HNC. Nevertheless, further optimization as well as efficacy studies are necessary to understand and improve in vivo tumour homing and determine the optimal experimental set-up of stem cell-based cancer therapies, including dosing and timing.
Several clinical and experimental studies have demonstrated that advanced glycation end products ... more Several clinical and experimental studies have demonstrated that advanced glycation end products (AGEs) are associated with adverse cardiac outcome. Growing evidence shows that high molecular weight AGEs (HMW-AGEs) might be as important as the characterized low molecular weight AGEs. To date, the role of HMW-AGEs in the pathogenesis of cardiac remodeling remains unknown. In this study, we investigated whether HMW-AGEs are involved in cardiac dysfunction. Healthy rats were daily ip injected with 20mg/kg BSA-derived HMW-AGEs or, as a control, unmodified BSA, during 6weeks. Cardiac function was assessed with echocardiography. Plasma levels of glucose, AGEs and soluble RAGE (sRAGE) were measured. AGEs, RAGE and lysyl oxidase (LOX) expression were determined by western blot. After 6weeks, animals displayed a sustained increase in circulating total AGEs without hyperglycemia. HMW-AGEs injections induced cardiac dysfunction characterized by wall hypertrophy, increased heart sphericity, reduced strain and strain rate with preserved ejection fraction. Plasma sRAGE levels were significantly higher compared to control and correlated significantly with decreased strain. RAGE expression, TNF-α and IL-6 remained unchanged. Finally, HMW-AGEs induced prominent cardiac fibrosis associated with an increased LOX expression. Our data demonstrate that rather than via a specific activation of RAGE, the deleterious effects of HMW-AGEs are likely mediated via an increased collagen cross-linking responsible for the observed cardiac stiffness. Additionally, we show that in the setting of elevated HMW-AGEs, increased sRAGE levels are markers of altered cardiac function.
The centre of the tooth harbours the dental pulp, a soft connective tissue which plays a pivotal ... more The centre of the tooth harbours the dental pulp, a soft connective tissue which plays a pivotal role in the homeostasis of tooth vitality and health. This tissue is highly vascularised and responsible for nutrient supply and waste removal. In addition, it contains an immune system as a defence against invading bacteria. Nevertheless, penetration of cariogenic bacteria can lead to necrosis of the tissue and blood vessels. Although current endodontic practice aims to sustain pulp vitality and tooth viability, the limitations associated with these procedures emphasise the need for alternative treatment protocols. The ideal therapeutic solution would be to regenerate a fully functional pulp tissue. As blood vessel formation is key in tissue regeneration, this process is the main focus of recent endodontic studies. This chapter first discusses the fundamental concepts of blood vessel development. Next, the morphology, ontogenesis and regulation of pulpal blood vessels are described. Finally, an overview on the preclinical advancements made to improve pulpal vascularisation is given: herein cell-free therapies using proteins and biodegradable scaffolds as well as the application of stem cells are discussed.
Although regenerative endodontic procedures have yielded an impressive body of favorable outcomes... more Although regenerative endodontic procedures have yielded an impressive body of favorable outcomes, the treatment of necrotic immature permanent teeth in particular remains to be a challenge. Recent advances in dental stem cell research have gained increasing insight in their regenerative potential and prospective use in the formation of viable dental tissues. Numerous studies already reported successful dental pulp regeneration following application of dental pulp stem cells, stem cells from the apical papilla or dental follicle precursor cells in different in vivo models. Next to responsive cells, dental tissue engineering also requires the support of an appropriate scaffold material, ranging from naturally occurring polymers to treated dentin matrix components. However, the routine use and banking of dental stem cells still holds some major challenges, such as culture-associated differences, patient-related variability and the effects of culture medium additives. Only in-depth evaluation of these problems and the implementation of standardized models and protocols will effectively lead to better alternatives for patients who no longer benefit from current treatment protocols.
bioRxiv (Cold Spring Harbor Laboratory), Dec 23, 2022
Macrophages play major roles in the pathophysiology of various neurological disorders, being invo... more Macrophages play major roles in the pathophysiology of various neurological disorders, being involved in seemingly opposing processes such as lesion progression and resolution. Yet, the molecular mechanisms that drive their harmful and benign effector functions remain poorly understood. Here, we demonstrate that extracellular vesicles (EVs) secreted by repair-associated macrophages (RAMs) enhance remyelination ex vivo and in vivo by promoting the differentiation of oligodendrocyte precursor cells (OPCs). Guided by lipidomic analysis and applying cholesterol depletion and enrichment strategies, we find that EVs released by RAMs show markedly elevated cholesterol levels and that cholestserol abundance controls their reparative impact on OPC maturation and remyelination. Mechanistically, EV-associated cholesterol was found to promote OPC differentiation through direct membrane fusion. Collectively, our findings highlight that EVs are essential for cholesterol trafficking in the brain and that changes in cholesterol abundance dictate the reparative impact of EVs released by macrophages in the brain, potentially having broad implications for therapeutic strategies aimed at promoting repair in neurodegenerative disorders.
Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been... more Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been admitted to the intensive care unit (ICU) often face months of physical disability after discharge. To optimize recovery, it is important to understand the role of musculoskeletal alterations in critically ill patients infected with SARS-CoV-2. The main aim of the present study was to describe the presence and morphology of nemaline bodies found in the skeletal muscle tissue from critically ill patients infected with SARS-CoV-2. In n = 7 patients infected with SARS-CoV-2, ultrastructural characteristics of vastus lateralis muscle obtained on days 1–3 and days 5–8 following ICU admission were investigated in more detail with electron microscopy. Those muscle biopsies consistently showed variable degrees of myofiber necrosis and myofibrillar disorganization. In 4/7 (57%) patients on days 5–8, the Z-line material accumulated into nemaline bodies with a typical lattice-like appearance at hi...
Background: Early detection of marginal bone loss is vital for treatment planning and prognosis o... more Background: Early detection of marginal bone loss is vital for treatment planning and prognosis of teeth and implant. This study was conducted to assess diagnostic accuracy of CBCT compared to intra-oral (IO) radiography for detection, classi cation and measurement of peri-implant bone defects in an animal model. Methods: Fifty-four mandible blocks with implants were harvested from nine male health adult beagle dogs with acquisition of IO, CBCT and micro-CT images from all samples. Peri-implant bone defects from 16 samples were diagnosed using micro-CT and classi ed into 3 defect categories: dehiscence (n = 5), infrabony defect (n = 3) and crater-like defect (n = 8). Following training and calibration of the observers, they asked to detect location (mesial, distal, buccal, lingual) and shape of the defect (dehiscence, horizontal defect, vertical defect, carter-like defect) utilizing both IO and CBCT images. Both observers assessed defect depth and width on IO, CBCT and micro-CT images at each side of peri-implant bone defect via CT-analyzer software. Data were analyzed using SPSS software and a p value of < 0.05 was considered as statistically signi cant. Results: Overall, there was a high diagnostic accuracy for detection of bone defects with CBCT images (sensitivity: 100%/100%), while IO images showed a reduction in accuracy (sensitivity: 69%/63%). Similarly, diagnostic accuracy for defect classi cation was signi cantly higher for CBCT, whereas IO images were unable to correctly identify vestibular dehiscence, with incorrect assessment of half of the infrabony defects. For accuracy of measuring defect depth and width, a higher correlation was observed between CBCT and gold standard micro-CT (r = 0.91, 95% CI: 0.86-0.94), whereas a lower correlation was seen for IO images (r = 0.82, 95%CI: 0.67-0.91). Conclusions: The diagnostic accuracy and reliability of CBCT was found to be superior to IO imaging for the detection, classi cation and measurement of peri-implant bone defects. The application of CBCT adds substantial information related to the peri-implant bone defect diagnosis and decision-making which cannot be achieved with conventional IO imaging.
The transplantation of pancreatic islets (PIs) containing insulin producing beta cells is conside... more The transplantation of pancreatic islets (PIs) containing insulin producing beta cells is considered an alternative approach for the treatment of type 1 diabetes mellitus (T1DM) [1]. Currently, different transplantation sites are assessed in clinical trials to improve outcome [2, 3]. To better monitor and validate the success of transplantation, it is desirable to monitor the location of engrafted islets noninvasively [4]. In vivo MR imaging of transplanted islets is one of the most suitable cell tracking methods, however, this requires labeling of the islets with a suitable contrast agent prior to transplantation [5-8]. In this study, we have tested the feasibility of cationic magnetoliposomes (MLs) compared to commercial contrast agents (Endorem and Resovist) by labeling insulinoma cells (INS1E) and freshly isolated rat PIs. It was possible to incorporate MR detectable amounts of MLs in a much shorter time (2 hours) without addition of transfection agents when compared to Endorem and Resovist. MLs did not show negative effects on the PIs viability and functional parameters in vitro. Further, labeled islets were transplanted in the renal sub-capsular region of healthy mice. Hypointense contrast in MR images due to the labeled PIs was detected in vivo upon transplantation. However MRI based detection was not possible when islets were labeled with Endorem and Resovist alone, but after addition of the transfection agent Poly-L-Lysin (PLL). The findings of this study indicate that MLs provides a satisfactory means to image pancreatic islets and have no deleterious effect on their function, which is promising for future pre-clinical and clinical studies involving the assessment of islet transplantation. Magnetoliposomes (MLs) are built up of nm-sized magnetite (Fe3O4) core, in which the original stabilizing lauric acid coat is first replaced by a phospholipid bilayer during incubation and dialysis of the fatty acid coated particle with performed small unilamellar phospholipid vesicles. Mechanistically, it has been proven that the process of ML formation is controlled by spontaneous transfer of phospholipids according to the so-called aqueous transfer model [9,10]. As MLs can be categorized as ‘ultrasmall superparamagnetic iron oxides’ (commonly designated as USPIO ́s), a high gradient magnetic field (HGM) is needed to withdraw the MLs from the incubation mixture. For a 14 nmdiameter iron oxide core covered with an intact phospholipid bilayer, typically, a phospholipid/Fe3O4 (mmol/g) ratio between 0.7 and 0.8 is calculated. The ligand exchange reaction can also be used to incorporate fluorophores (fluorescent labels for microscopic validation) or targeting molecules (small molecules targeting the GLUT2, monoclonal antibodies and potentially nanobodies) to the MLs double-layer.
Mandibular repositioning devices (MRDs) increase the patency of the upper airway by repositioning... more Mandibular repositioning devices (MRDs) increase the patency of the upper airway by repositioning the mandible forward, resulting in displacement of the oropharyngeal tissues preventing upper airway collapsibility. Mandibular anterior repositioning is counteracted by muscle force from the temporalis muscle. A 39-year-old man had an osteolytic lesion with fracture of the coronoid process of the mandible secondary to wearing a MRD for sleep apnea. Continuous stress generated on the coronoid process temporalis muscle resulted in osteolysis and fracture of the coronoid process on the patient&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s right side, resulting in swelling and limited ability to open his mouth. The patient was managed with intravenous antibiotics to control the osteomyelitis and surgical debridement, with removal of the coronoid process of the mandible. It is unclear why the fracture only occurred on the right side. Pathologic fracture of the coronoid process due to chronic stress and secondary osteomyelitis is a rare severe complication of treatment for obstructive sleep apnea syndrome with a MRD.
Journal of Oral and Maxillofacial Surgery, Oct 1, 2018
Trigeminal neuralgia is characterized by unilateral pain in the region supplied by the sensory di... more Trigeminal neuralgia is characterized by unilateral pain in the region supplied by the sensory distribution of the fifth cranial nerve. Pharmacologic therapy is an adequate initial treatment option in 75% of patients. When the Jannetta surgical operation is not available or not indicated and when conservative treatment fails to relieve the pain or the medication has to be discontinued because of side effects, one of the remaining surgical options is cryosurgery in the peripherally distributed nerves that emanate from the trigeminal nerve. This technical note describes a perioperative method for exposing and mobilizing the inferior alveolar nerve (IAN) from its bony canal. This approach provided easy access to infratemporal fossa structures during cryotherapy. This technique represented a further development of the technique previously described by the authors. This method ensured direct visualization of the IAN and wide access to theinfratemporal fossa during IAN cryotherapy.
British Journal of Oral & Maxillofacial Surgery, Oct 1, 2020
Please cite this article in press as: da Costa Senior O, et al. Long-term neurosensory disturbanc... more Please cite this article in press as: da Costa Senior O, et al. Long-term neurosensory disturbances after modified sagittal split osteotomy.
International Journal of Oral Science, Jul 14, 2017
The main goal of this study was to introduce a novel three-dimensional procedure to objectively q... more The main goal of this study was to introduce a novel three-dimensional procedure to objectively quantify both inner and outer condylar remodelling on preoperative multi-slice computed tomography (MSCT) and postoperative cone-beam computed tomography (CBCT) images. Second, the reliability and accuracy of this condylar volume quantification method was assessed. The mandibles of 20 patients (11 female and 9 male) who underwent bimaxillary surgery were semi-automatically extracted from MSCT/CBCT scans and rendered in 3D. The resulting condyles were spatially matched by using an anatomical landmark-based registration procedure. A standardized sphere was created around each condyle, and the condylar bone volume within this selected region of interest was automatically calculated. To investigate the reproducibility of the method, inter-and intra-observer reliability was calculated for assessments made by two experienced radiologists twice five months apart in a set of ten randomly selected patients. To test the accuracy of the bone segmentation, the inner and outer bone structures of one dry mandible, scanned according to the clinical setup , were compared with the gold standard, micro-CT. Thirty-eight condyles showed a significant (Po0.05) mean bone volume decrease of 26.4% ± 11.4% (502.9 mm 3 ± 268.1 mm 3). No significant effects of side, sex or age were found. Good to excellent (ICC40.6) intra-and inter-observer reliability was observed for both MSCT and CBCT. Moreover, the bone segmentation accuracy was less than one voxel (0.4 mm) for MSCT (0.3 mm ± 0.2 mm) and CBCT (0.4 mm ± 0.3 mm), thus indicating the clinical potential of this method for objective follow-up in pathological condylar resorption.
Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in child... more Tooth autotransplantation (TAT) offers a viable biological approach to tooth replacement in children and adolescents. The aim of this study was to evaluate the outcome of the cone-beam computed tomographic (CBCT)-guided TAT compared to the conventional TAT protocol and to assess the 3-dimensional (3D) patterns of healing after CBCT-guided TAT (secondary aim). This study included 100 autotransplanted teeth in 88 patients. Each experimental group consisted of 50 transplants in 44 patients (31 males and 19 females). The mean (SD) age at the time of surgery was 10.7 (1.1) y for the CBCT-guided group. This was 10.6 (1.3) y for the conventional group. The mean (SD) follow-up period was 4.5 (3.1) y (range, 1.1 to 10.4 y). Overall survival rate for the CBCT-guided TAT was 92% with a success rate of 86% compared to an 84% survival rate and a 78% success rate for the conventional group (P > 0.005). The following measurements were extracted from the 3D analysis: root hard tissue volume (RV), root length (RL), apical foramen area (AFA), and mean and maximum dentin wall thickness (DWT). Overall, the mean (SD) percentage of tissue change was as follows: RV gain by 65.8% (34.6%), RL gain by 37.3% (31.5%), AFA reduction by 91.1% (14.9%), mean DWT increase by 107.9% (67.7%), and maximum DWT increase by 26.5% (40.1%). Principal component analysis (PCA) identified the mean DWT, RV, and maximum DWT as the parameters best describing the tissue change after TAT. Cluster analysis applied to the variables chosen by the PCA classified the CBCT group into 4 distinct clusters (C1 = 37.2%, C2 = 17.1%, C3 = 28.6%, C4 = 17.1%), revealing different patterns of tissue healing after TAT. The CBCT-guided approach increased the predictability of the treatment. The 3D analysis provided insights into the patterns of healing. CBCT-guided TAT could be adopted as an alternative for the conventional approach. (Clinical trial center and ethical board University Hospitals, KU Leuven: S55287; ClinicalTrials.gov Identifier: NCT02464202
bioRxiv (Cold Spring Harbor Laboratory), Apr 2, 2023
Duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A) and is known to disrupt t... more Duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A) and is known to disrupt the lipid metabolism in myelinating Schwann cells by unknown mechanisms. By using two CMT1A mouse models overexpressing human PMP22, we discovered that PMP22 dose-dependently downregulates genes that are involved in lipid and cholesterol metabolism. Lipidomic analysis on CMT1A mouse sciatic nerves confirmed lipid metabolic abnormalities primarily associated with cholesterol and sphingolipids. We observed similar lipidomic profiles and downregulation of genes associated with lipid metabolism in human CMT1A patient induced pluripotent stem cell-derived Schwann cell precursors (iPSC-SCPs). We confirmed these findings by demonstrating altered lipid raft dynamics and plasma membrane fluidity in CMT1A iPSC-SCPs. Additionally, we identified impaired cholesterol incorporation in the plasma membrane due to altered lipid storage homeostasis in CMT1A iPSC-SCPs, which could be modulated by changing the lipid composition of the cell culture medium. These findings suggest that PMP22 plays a role in regulating the lipid composition of the plasma membrane and lipid storage homeostasis. Targeting lipid metabolism may hold promise as a potential treatment for CMT1A patients.
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