Toward high-resolution 3D-printing of pharmaceutical implants - A holistic analysis of relevant material properties and process parameters.

In this work, filament-based 3D-printing, the most widely used sub-category of material extrusion additive manufacturing (MEAM), is presented as a promising manufacturing platform for the production of subcutaneous implants. Print nozzle diameters as small as 100 µm were utilized demonstrating MEAM of advanced porous internal structures at the given cylindrical implant geometry of 2 mm × 40 mm. The bottlenecks related to high-resolution MEAM of subcutaneous implants are systematically analyzed and the print process is optimized accordingly. Custom synthesized biodegradable phase-separated poly(ether ester) multiblock copolymers exhibiting appropriate melt viscosity at comparatively low printing temperatures of 135 °C and 165 °C were utilized as 3D-printing feedstock. The print process was optimized to minimize thermomechanical polymer degradation by employing print speeds of 30 mm∙s-1 in combination with a nozzle diameter of 150 µm at layer heights of 110 µm. These results portray the basis for further development of subcutaneous implantable drug delivery systems where drug release profiles can be tailored through the adaption of the internal implant structure, which cannot be achieved using existing manufacturing techniques.

Radiofrequency Ablation of Re-entrant Atrial Tachycardia Originating from the Superior Vena Cava with a High-resolution, 3-dimensional Mapping System.

An 80-year-old man with no previous history of catheter ablation or cardiac surgery underwent catheter ablation for atrial tachycardia (AT). We suspected that the mechanism causing AT was re-entry indicated by the entrainment phenomenon during AT and through activation mapping with a 3-dimensional mapping system (EnSite™ X EP system; Abbott, Chicago, IL, USA). We used a multipolar catheter (Advisor™ HD Grid Mapping Catheter; Abbott) inserted into the superior vena cava (SVC) to accomplish activation mapping. The AT circuit was localized inside the SVC with a fractionated potential recorded on its right lateral wall. A similar fractionated potential was observed in the surrounding area. These areas functioned as the critical isthmus of the AT. Radiofrequency (RF) catheter ablation at these sites eliminated the tachycardia. After RF delivery, no tachycardia was induced by programmed stimulation, even during isoproterenol infusion. Consequently, there was no recurrence of tachycardia even after catheter ablation.

Hybrid spheroid microscaffolds as modular tissue units to build macro-tissue assemblies for tissue engineering.

Since its inception, tissue engineering and regenerative medicine (TERM) has been relying on either scaffold-based or scaffold-free strategies. Recent reports outlined the possibility of a synergistic, convergence approach, referred to as the third TERM strategy, which could alleviate bottlenecks of the two previous options. This strategy requires the fabrication of highly porous microscaffolds, allowing to create single spheroids within each of them. The resulting tissue units can then be combined and used as modular building blocks for creating tissue constructs through a bottom-up self-assembly. Such strategy can have a significant impact for the future of TERM, but so far, no reports have assessed its feasibility in detail. This work reports a first systematic study, which includes a comparison of the in vitro behavior of tissue units based on adipose derived stem cell spheroids cultured within microscaffolds versus conventional spheroids. We first proved that the presence of the microscaffold neither impairs the cells 'ability to form spheroids nor impacts their viability. Importantly, the fusiogenic and the differentiation potential (i.e. chondrogenesis and osteogenesis), which are important features for cellularized building blocks to be used in TERM, are preserved when spheroids are cultured within microscaffolds. Significant benefits of microscaffold-based tissue units include the enhanced cell retention, the decreased compaction and the better control over the size observed when larger tissue constructs are formed through self-assembly. The proof of concept study presented here demonstrates the great potential offered by those microsize tissue units to be used as building blocks for directed tissue self-assembly. STATEMENT OF SIGNIFICANCE: One of the most exciting and recent advances in tissue engineering and regenerative medicine (TERM) is to combine together multiple micro-size cellularized units, which are able to self-assemble altogether to recreate larger tissue constructs. In this work, we produce such modules by forming single spheroids within highly porous microscaffolds, and study how this new microenvironment impacts on the spheroid's behavior and stemness potential. This work highlights as well that such novel route is enabled by two-photon polymerization, which is an additive manufacturing technique offering high spatial resolution down to 100 nm. These findings provide a first scientific evidence about the utilization of hybrid spheroid microscaffold-based tissue units with great perspective as a modular tool for TERM.

Combining Photogrammetry and Photometric Stereo to Achieve Precise and Complete 3D Reconstruction.

Image-based 3D reconstruction has been employed in industrial metrology for micro-measurements and quality control purposes. However, generating a highly-detailed and reliable 3D reconstruction of non-collaborative surfaces is still an open issue. In this paper, a method for generating an accurate 3D reconstruction of non-collaborative surfaces through a combination of photogrammetry and photometric stereo is presented. On one side, the geometric information derived with photogrammetry is used in areas where its 3D measurements are reliable. On the other hand, the high spatial resolution capability of photometric stereo is exploited to acquire a finely detailed topography of the surface. Finally, three different approaches are proposed to fuse both geometric information and high frequency details. The proposed method is tested on six different non-collaborative objects with different surface characteristics. To evaluate the accuracy of the proposed method, a comprehensive cloud-to-cloud comparison between reference data and 3D points derived from the proposed fusion methods is provided. The experiments demonstrated that, despite correcting global deformation up to an average RMSE of less than 0.1 mm, the proposed method recovers the surface topography at the same high resolution as the photometric stereo.

Pediatric reference values of anterior visual pathway structures measured with axis-correction on high-resolution 3D T2 fast spin echo sequences.

BACKGROUND: The size of the anterior visual pathway (AVP) structures is affected by patient age and pathology. Normative data is useful when determining whether pathology is present. AVP structures do not respect the standard planes of magnetic resonance (MR) imaging. The aim of this study was to produce normative age-related and axis-corrected data of the AVP structures using multiplanar reformation (MPR) of high-resolution 3D T2-weighted fast spin echo (3D T2w FSE) images. METHODS: For each patient 32 measurements of AVP structures were obtained in 145 children (2 months - 18 years) with normal brain MR studies on high-resolution 3D T2w FSE images adjusted to the axis of each AVP structure. Descriptive statistics were calculated for different age classes and growth models were fitted to the data and assessed for their performance to create a formal statistical model that allows inference beyond the sample. RESULTS: Descriptive statistics were compiled in a reference table and prediction plots in relation to age, height, and body surface area (BSA) were obtained from the best overall performing statistical model, also taking field strength (1.5 vs. 3 T) into account. Intraclass correlation coefficient values were calculated for all variables ranging from 0.474 to 0.967, the most reliable being the transverse diameter of the globe, the maximum diameter of the retrobulbar nerve sheath, the intracranial segment of the optic nerve and the transverse diameter of the chiasm. The maximum retrobulbar diameter of the optic nerve sheath and the lateral superoinferior diameter of the chiasm showed no statistically significant change with age. CONCLUSION: Detailed charts of reference values for AVP structures as well as prediction plots in relation to age, height and BSA were established using axis-corrected measurements from the MPR of high-resolution 3D T2w FSE images. Furthermore, an Excel spreadsheet that allows users to calculate normative values for the 9 AVP structures of key interest is provided as supplementary material.

High resolution 3D magnetic resonance imaging of Gruber's ligament: a pilot study.

INTRODUCTION: Gruber's ligament (GL), a surgical landmark, extends from the lateral upper clivus to the petrous apex (PA), forming the superior boundary of Dorello's canal (DC). It overlies the interdural segment of the abducens nerve (CN VI). High-resolution 3D skull base MRI (SB-MRI) demonstrates anatomic details visible to the surgeon, but not well seen on traditional cross-sectional imaging. The aim of this study was to demonstrate visualization of the GL and its relationship to CN VI utilizing contrast enhanced high-resolution SB-MRI. METHODS: Two neuroradiologists retrospectively reviewed in consensus the SB-MRIs of 27 skull base sides, among 14 patients. GL detection rate, confidence of detection, and GL length were recorded. When GL was successfully identified, the position of the interdural segment of CN VI within DC was recorded. RESULTS: GL was readily identified in 16 skull base sides (59%), identified with some difficulty in 2 skull base sides (7%), and failed to be identified in 9 skull base sides (33%). The mean GL length was 7.1 mm (4.5-9.3 mm). Among the 18 cases where GL was successfully identified, CN VI was readily identified in all cases (100%), coursing the lateral third of DC in 72% of sides, and middle third in the remaining 28% of sides. CONCLUSION: GL can be identified in approximately two-thirds of cases utilizing 3D high resolution SB-MRI. CN VI passes most commonly along the lateral third of DC. This is the first report demonstrating visualization of GL and its relation to CN VI, on imaging.

Advanced high resolution three-dimensional imaging to visualize the cerebral neurovascular network in stroke.

As an important method to accurately and timely diagnose stroke and study physiological characteristics and pathological mechanism in it, imaging technology has gone through more than a century of iteration. The interaction of cells densely packed in the brain is three-dimensional (3D), but the flat images brought by traditional visualization methods show only a few cells and ignore connections outside the slices. The increased resolution allows for a more microscopic and underlying view. Today's intuitive 3D imagings of micron or even nanometer scale are showing its essentiality in stroke. In recent years, 3D imaging technology has gained rapid development. With the overhaul of imaging mediums and the innovation of imaging mode, the resolution has been significantly improved, endowing researchers with the capability of holistic observation of a large volume, real-time monitoring of tiny voxels, and quantitative measurement of spatial parameters. In this review, we will summarize the current methods of high-resolution 3D imaging applied in stroke.

3D direct-write printing of water soluble micromoulds for high-resolution rapid prototyping.

Direct-write printing has contributed tremendously to additive manufacturing; in particular extrusion based printing where it has extended the range of materials for 3D printing and thus enabled use across many more sectors. The printing inks for direct-write printing however, need careful synthesis and invariably undergo extensive preparation before being able to print. Hence, new ink synthesis efforts are required every time a new material is to be printed; this is particularly challenging for low storage modulus (G') materials like silicones, especially at higher resolutions (under 10 µm). Here we report the development of a precise (< 10 µm) 3D printable polymer, with which we 3D print micromoulds which are filled with standard silicones like polydimethylsiloxane (PDMS) and left to cure at room temperature. The proof of concept is demonstrated using a simple water soluble polymer as the mould material. The approach enables micrometre scale silicone structures to be prototyped with ease, away from the cleanroom.

Study of Pavement Micro- and Macro-Texture Evolution Due to Traffic Polishing Using 3D Areal Parameters.

Pavement micro- and macro-texture have significant effects on roadway friction and driving safety. The influence of traffic polish on pavement texture has been investigated in many laboratory studies. This paper conducts field evaluation of pavement micro- and macro-texture under actual traffic polishing using three-dimensional (3D) areal parameters. A portable high-resolution 3D laser scanner measured pavement texture from a field site in 2018, 2019, and 2020. Then, the 3D texture data was decomposed to micro- and macro-texture using Fourier transform and Butterworth filter methods. Twenty 3D areal parameters from five categories, including height, spatial, hybrid, function, and feature parameters, were calculated to characterize pavement micro- and macro-texture. The results demonstrate that the 3D areal parameters provide an alternative to comprehensively characterize the evolution of pavement texture under traffic polish from different aspects.

Diagnostic Accuracy of Sagittal TSE-T2W, Variable Flip Angle 3D TSET2W and High-resolution 3D Heavily T2W Sequences for the Stenosis of Two Localizations: The Cerebral Aqueduct and the Superior Medullary Velum.

OBJECTIVES: This study aimed to investigate the accuracy of conventional Sagittal Turbo spin Echo T2-weighted (Sag TSE-T2W), variable flip angle 3D TSE (VFA-3D-TSE) and high-resolution 3D heavily T2W (HR-3D-HT2W) sequences in the diagnosis of primary aqueductal stenosis (PAS) and Superior Medullary Velum Stenosis (SMV-S), and the effect of stenosis localization on diagnosis. METHODS: Seventy-seven patients were included in the study. The diagnosis accuracy of the HR-3D-HT2W, Sag TSE-T2W and VFA-3D-TSE sequences, was classified into three grades by two experienced neuroradiologists: grade 0 (the sequence has no diagnostic ability), grade 1 (the sequence diagnoses stenosis but does not show focal stenosis itself or membrane formation), and grade 2 (the sequence makes a definitive diagnosis of stenosis and shows focal stenosis itself or membrane formation). Stenosis localizations were divided into three as Cerebral Aquaduct (CA), Superior Medullary Velum (SMV) and SMV+CA. In the statistical analysis, the grades of the sequences were compared without making a differentiation based on localization. Then, the effect of localization on diagnosis was determined by comparing the grades for individual localizations. RESULTS: In the sequence comparison, grade 0 was not detected in the VFA-3D-TSE and HR-3DHT2W sequences, and these sequences diagnosed all cases. On the other hand, 25.4% of grade 0 was detected with the Sag TSE-T2W sequence (P<0.05). Grade 1 was detected by VFA-3D-TSE in 23% of the cases, while grade 1 (12.5%) was detected by HRH-3D-T2W in only one case, and the difference was statistically significant (P<0.05). When the sequences were examined according to localizations, the rate of grade 0 in the Sag TSE-T2W sequence was statistically significantly higher for the SMV localization (33.3%) compared to CA (66.7%) and SMV+CA (0%) (P<0.05). Localization had no effect on diagnosis using the other sequences. CONCLUSION: In our study, we found that the VFA-3D-TSE and HR-3D-HT2W sequences were successful in the diagnosis of PAS and SMV-S contrary to the Sag TSE-T2W sequence and especially SMV localization decreases the diagnostic accuracy of Sag TSE-T2W sequence.

Coma-corrected rapid single-particle cryo-EM data collection on the CRYO ARM 300.

Single-particle cryogenic electron microscopy has recently become a major method for determining the structures of proteins and protein complexes. This has markedly increased the demand for throughput of high-resolution electron microscopes, which are required to produce high-resolution images at high rates. An increase in data-collection throughput can be achieved by using large beam-image shifts combined with off-axis coma correction, enabling the acquisition of multiple images from a large area of the EM grid without moving the microscope stage. Here, the optical properties of the JEOL CRYO ARM 300 electron microscope equipped with a K3 camera were characterized under off-axis illumination conditions. It is shown that efficient coma correction can be achieved for beam-image shifts with an amplitude of at least 10 µm, enabling a routine throughput for data collection of between 6000 and 9000 images per day. Use of the benchmark for the rapid data-collection procedure (with beam-image shifts of up to 7 µm) on apoferritin resulted in a reconstruction at a resolution of 1.7 Å. This demonstrates that the rapid automated acquisition of high-resolution micrographs is possible using a CRYO ARM 300.

High-resolution MR imaging of cranial neuropathy in patients with anti-GQ1b antibody syndrome.

OBJECTIVE: The value of conventional MRI in patients anti-GQ1b antibody syndrome is subject to debate. Our purpose was to evaluate the diagnostic accuracy of high-resolution MRI for detecting cranial nerve abnormalities in patients with anti-GQ1b antibody syndrome. MATERIALS AND METHODS: This retrospective cohort study enrolled 15 anti-GQ1b-positive patients diagnosed with MFS and related disorders and 17 age-matched controls, all of whom underwent high-resolution MR imaging including pre-contrast and contrast-enhanced (CE) 3D FLAIR and 3D CE T1-weighted turbo field echo (T1-TFE) between 2010 and 2016. The diagnostic performance of high-resolution MRI was assessed using the area under the curve (AUC) of the receiver operating characteristics curve. Inter- and intraobserver agreements were calculated using kappa statistics and intraclass correlation coefficients (ICC), respectively. RESULTS: Ophthalmoplegia, ataxia, and hypo/areflexia were present in 100%, 60%, and 67%, respectively. Other neurologic findings included ptosis (40%), mydriasis (13%), and facial (27%) and bulbar (13%) palsy. Fourteen of sixteen (88%) MR examinations in 15 patients demonstrated at least one cranial nerve abnormality corresponding to the clinical findings. The involved cranial nerves on MRI were the IIIrd cranial nerve in 14 patients, VIth in nine, VIIth in four, Vth in one, and VIIIth in one. AUC values for detecting cranial neuropathy on high-resolution MRI were 0.938 (95% CI: 0.795-0.992) on a per patient basis. Inter- and intraobserver agreements were 0.842 and 0.945, respectively. CONCLUSION: High-resolution 3D FLAIR and CE 3D T1-TFE MRI has high reliability and accuracy for demonstrating cranial neuropathy in patients with anti-GQ1b antibody syndrome.

Muscular loading affects the 3D structure of both the mineralized rudiment and growth plate at early stages of bone formation.

Fetal immobilization affects skeletal development and can lead to severe malformations. Still, how mechanical load affects embryonic bone formation is not fully elucidated. This study combines mechanobiology, image analysis and developmental biology, to investigate the structural effects of muscular loading on embryonic long bones. We present a novel approach involving a semi-automatic workflow, to study the spatial and temporal evolutions of both hard and soft tissues in 3D without any contrast agent at micrometrical resolution. Using high-resolution phase-contrast-enhanced X-ray synchrotron microtomography, we compare the humeri of Splotch-delayed embryonic mice lacking skeletal muscles with healthy littermates. The effects of skeletal muscles on bone formation was studied from the first stages of mineral deposition (Theiler Stages 23 and 24) to just before birth (Theiler Stage 27). The results show that muscle activity affects both growth plate and mineralized regions, especially during early embryonic development. When skeletal muscles were absent, there was reduced mineralization, altered tuberosity size and location, and, at early embryonic stages, decreased chondrocyte density, size and elongation compared to littermate controls. The proposed workflow enhances our understanding of mechanobiology of early bone formation and could be implemented for the study of other complex biological tissues.

Assessing the JEOL CRYO ARM 300 for high-throughput automated single-particle cryo-EM in a multiuser environment.

Single-particle cryo-EM has become an indispensable structural biology method. It requires regular access to high-resolution electron cryogenic microscopes. To fully utilize the capacity of the expensive high-resolution instruments, the time used for data acquisition and the rate of data collection have to be maximized. This in turn requires high stability and high uptime of the instrument. One of the first 300 kV JEOL CRYO ARM 300 microscopes has been installed at the cryo-EM facility BECM at VIB-VUB, Brussels, where the microscope is used for continuous data collection on multiple projects. Here, the suitability and performance of the microscope is assessed for high-throughput single-particle data collection. In particular, the properties of the illumination system, the stage stability and ice contamination rates are reported. The microscope was benchmarked using mouse heavy-chain apoferritin which was reconstructed to a resolution of 1.9 Å. Finally, uptime and throughput statistics of the instrument accumulated during the first six months of the facility operation in user access mode are reported.

High resolution 3D intraosseous vascular model of the scaphoid bone reconstructed by micro CT / 解剖学报

[Abstract] Objective The purpose of this study is to construct a high-resolution model focusing on the vascular pattern of the scaphoid by using micro CT and to provide anatomical reference for the daily clinical use. Methods The lead-based contrast was perfused from the brachial artery and then the scaphoid bone was harvested. 3D models of the scaphoid bones were constructed by using micro CT to show how arteries distributed in and on the bones. Results The arteries on the surface stretched from the distal radius covered with scaphoid fossa to the radial side of the waist and then head back to the distal ulna along the dorsoradial ridge, formed like a letter “Ⅴ”. The arteries gathered at the inflection point of the letter “Ⅴ” and the dorsal region. The tubercle region was anastomosed extensively with 3 to 5 major intraosseous vessels originated from the extraosseous vessels covering the waist and the tubercle. There are only 1 to 2 major intraosseous vessels entering the bone via a long route from the ulnar side. The vessels running in the scapholunate ligament didn’t spilt into any intraosseous branches. Conclusion The superficial vascularity formes a “Ⅴ”-like pattern. The inflection point of the letter “Ⅴ” and the dorsal region display a dense vascularization and these vessels contributed a lot to the intraosseous vascularity.

An unusual propagation pattern along the tricuspid annulus after cavo-tricuspid isthmus ablation: Insights into posterior transverse conduction revealed by an ultra-high-resolution 3-dimensional mapping system.

Cavo-tricuspid isthmus (CTI) ablation is a cornerstone of atrial flutter ablation. The goal of CTI-dependent flutter ablation is achievement of bidirectional CTI block. Usually bidirectional CTI block is confirmed by atrial activation during septal and lateral atrial pacing or the use of differential pacing maneuvers. According to the pathological findings, the transmural muscle fibers connect the endo- and epicardium. An epicardial-endocardial breakthrough (EEB) sometimes interferes with the confirmation of bidirectional block. Recently, a new ultra-high-resolution 3-dimentional mapping systems (Rhythmia®, Boston Scientific, Marlborough [Cambridge] MA, USA) that allows rapid ultra-high-resolution electroanatomical mapping was introduced. A 64-year-old man with a sustained atrial flutter (AFL) was referred to us. Catheter ablation was performed using an ultra-high-resolution 3-dimensional mapping system. Here, we report the case of a patient with an EEB visualized by ultra-high-resolution 3-dimensional mapping. .

An Immature Ten-year Long-standing Case of Ossifying Fibroma.

Ossifying fibroma is a rare benign bone neoplasm common in middle age, with definite female predominance. Here, we describe a case of an ossifying fibroma in a 36-year-old female, with a right facial deformity. The lesion had been present for almost 10 years. The panoramic image showed a multilocular appearance with scattered radiopacities. Advanced imaging revealed an expansile multilocular lesion with multiple small radiopaque foci and a few dense radiopaque masses. A histopathological examination confirmed the diagnosis. The case represents a non-aggressive form of an immature ossifying fibroma.

Two-photon microscopy of fungal keratitis-affected rabbit cornea ex vivo using moxifloxacin as a labeling agent.

Two-photon microscopy (TPM) is a three dimensional (3D) microscopic technique based on nonlinear two-photon fluorescence, which has been tested as an alternative to reflectance confocal microscopy (RCM) for detecting fungal keratitis via optical imaging. Although TPM provided images with better contrast than RCM for fungal keratitis, its imaging speed was relatively low because of weak intrinsic signal. Moxifloxacin, a Food and Drug Administration (FDA)-approved antibiotic, was recently used as a cell-labeling agent for TPM. In this study, moxifloxacin was used to label fungal cells for TPM imaging of fungal keratitis models. Fungal cell suspensions and ex vivo fungal keratitis-affected rabbit corneas were prepared using two types of fungal pathogens, Aspergillus fumigatus and Candida albicans, and TPM imaging was performed both with and without moxifloxacin treatment. Fungal cells with enhanced fluorescence were clearly visible by TPM of moxifloxacin-treated fungal cell suspensions. TPM of moxifloxacin-treated fungal keratitis rabbit corneas revealed both the infecting fungal cells and corneal cells similar to those observed in TPM without moxifloxacin treatment, albeit with approximately 10-times enhanced fluorescence. Fungal cells were distinguished from corneal cells on the basis of their distinct morphologies. Thus, TPM with moxifloxacin labeling might be useful for the detection of fungal keratitis at the improved imaging speed.

A novel mouse model of human prostate cancer to study intraprostatic tumor growth and the development of lymph node metastases.

BACKGROUND: In this study, we aimed to establish a versatile in vivo model of prostate cancer, which adequately mimics intraprostatic tumor growth, and the natural routes of metastatic spread. In addition, we analyzed the capability of high-resolution ultrasonography (hrUS), in vivo micro-CT (µCT), and 9.4T MRI to monitor tumor growth and the development of lymph node metastases. METHODS: A total of 5 × 105 VCaP cells or 5 × 105 cells of LuCaP136- or LuCaP147 spheroids were injected into the prostate of male CB17-SCID mice (n = 8 for each cell type). During 12 weeks of follow-up, orthotopic tumor growth, and metastatic spread were monitored by repetitive serum-PSA measurements and imaging studies including hrUS, µCT, and 9.4T MRI. At autopsy, primary tumors and metastases were harvested and examined by histology and immunohistochemistry (CK5, CK8, AMACR, AR, Ki67, ERG, and PSA). From imaging results and PSA-measurements, tumor volume doubling time, tumor-specific growth rate, and PSA-density were calculated. RESULTS: All 24 mice developed orthotopic tumors. The tumor growth could be reliably monitored by a combination of hrUS, µCT, MRI, and serum-PSA measurements. In most animals, lymph node metastases could be detected after 12 weeks, which could also be well visualized by hrUS, and MRI. Immunohistochemistry showed positive signals for CK8, AMACR, and AR in all xenograft types. CK5 was negative in VCaP- and focally positive in LuCaP136- and LuCaP147-xenografts. ERG was positive in VCaP- and negative in LuCaP136- and LuCaP147-xenografts. Tumor volume doubling times and tumor-specific growth rates were 21.2 days and 3.9 %/day for VCaP-, 27.6 days and 3.1 %/day for LuCaP136- and 16.2 days and 4.5 %/day for LuCaP147-xenografts, respectively. PSA-densities were 433.9 ng/mL per milliliter tumor for VCaP-, 6.5 ng/mL per milliliter tumor for LuCaP136-, and 11.2 ng/mL per milliliter tumor for LuCaP147-xenografts. CONCLUSIONS: By using different monolayer and 3D spheroid cell cultures in an orthotopic xenograft model, we established an innovative, versatile in vivo model of prostate cancer, which enables the study of both intraprostatic tumor growth as well as metastatic spread to regional lymph nodes. HrUS and MRI are feasible tools to monitor tumor growth and the development of lymph node metastases while these cannot be visualized by µCT.

Fabrication of biomimetic placental barrier structures within a microfluidic device utilizing two-photon polymerization.

The placenta is a transient organ, essential for development and survival of the unborn fetus. It interfaces the body of the pregnant woman with the unborn child and secures transport of endogenous and exogenous substances. Maternal and fetal blood are thereby separated at any time, by the so-called placental barrier. Current in vitro approaches fail to model this multifaceted structure, therefore research in the field of placental biology is particularly challenging. The present study aimed at establishing a novel model, simulating placental transport and its implications on development, in a versatile but reproducible way. The basal membrane was replicated using a gelatin-based material, closely mimicking the composition and properties of the natural extracellular matrix. The microstructure was produced by using a high-resolution 3D printing method - the two-photon polymerization (2PP). In order to structure gelatin by 2PP, its primary amines and carboxylic acids are modified with methacrylamides and methacrylates (GelMOD-AEMA), respectively. High-resolution structures in the range of a few micrometers were produced within the intersection of a customized microfluidic device, separating the x-shaped chamber into two isolated cell culture compartments. Human umbilical-vein endothelial cells (HUVEC) seeded on one side of this membrane simulate the fetal compartment while human choriocarcinoma cells, isolated from placental tissue (BeWo B30) mimic the maternal syncytium. This barrier model in combination with native flow profiles can be used to mimic the microenvironment of the placenta, investigating different pharmaceutical, clinical and biological scenarios. As proof-of-principle, this bioengineered placental barrier was used for the investigation of transcellular transport processes. While high molecular weight substances did not permeate, smaller molecules in the size of glucose were able to diffuse through the barrier in a time-depended manner. We envision to apply this bioengineered placental barrier for pathophysiological research, where altered nutrient transport is associated with health risks for the fetus.