Development of an adjustable patient-specific rigid guide to improve the accuracy of external ventricular catheter placement

OBJECTIVE

The most common method for external ventricular drain (EVD) placement is the freehand approach, which has reported inaccuracy rates of 12.3%-44.9%, especially in the case of altered ventricular anatomy. Current assistive devices require added time or equipment or do not account for shifted ventricles. To improve the accuracy of emergent EVD placement in the setting of altered ventricular anatomy, the authors designed a patient-specific EVD (PS-EVD) guide.

METHODS

The PS-EVD guide has a tripod base and a series of differently angled inserts that lock in place at multiple rotational positions, allowing for numerous insertion angles. For testing, the authors designed a 3D-printed phantom skull with a gelatin brain analog containing ventricles simulating normal and altered ventricular anatomy. Low-resolution CT scans of the phantom were used to calculate the insertion angle in relation to the standard perpendicular entry. The corresponding insert at the correct rotational position within the base unit was positioned over the entry point on the phantom, and the catheter was inserted. Accuracy was evaluated with repeat CT scans.

RESULTS

With normal ventricular anatomy, as well as abnormally shifted ventricles, proper use of the PS-EVD guide led to accurate catheter insertion into the ventricle in trials, as confirmed on coronal and sagittal CT images, including cases in which a perpendicular trajectory, such as with the Ghajar guide, was insufficient.

CONCLUSIONS

The PS-EVD guide allows consistent and accurate EVD placement in phantom skulls with both normal and altered ventricular anatomy. Further trials comparing this device to the freehand approach are required.

Bioreactor Technologies for Enhanced Organoid Culture

An organoid is a 3D organization of cells that can recapitulate some of the structure and function of native tissue. Recent work has seen organoids gain prominence as a valuable model for studying tissue development, drug discovery, and potential clinical applications. The requirements for the successful culture of organoids in vitro differ significantly from those of traditional monolayer cell cultures. The generation and maturation of high-fidelity organoids entails developing and optimizing environmental conditions to provide the optimal cues for growth and 3D maturation, such as oxygenation, mechanical and fluidic activation, nutrition gradients, etc. To this end, we discuss the four main categories of bioreactors used for organoid culture: stirred bioreactors (SBR), microfluidic bioreactors (MFB), rotating wall vessels (RWV), and electrically stimulating (ES) bioreactors. We aim to lay out the state-of-the-art of both commercial and in-house developed bioreactor systems, their benefits to the culture of organoids derived from various cells and tissues, and the limitations of bioreactor technology, including sterilization, accessibility, and suitability and ease of use for long-term culture. Finally, we discuss future directions for improvements to existing bioreactor technology and how they may be used to enhance organoid culture for specific applications.

Soy Protein Nanofiber Scaffolds for Uniform Maturation of Human Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium

Retinal pigment epithelium (RPE) differentiated from human induced pluripotent stem cells, called induced retinal pigment epithelium (iRPE), is being explored as a cell-based therapy for the treatment of retinal degenerative diseases, especially age-related macular degeneration. The success of RPE implantation is linked to the use of biomimetic scaffolds that simulate Bruch's membrane and promote RPE maturation and integration as a functional tissue. Due to difficulties associated with animal protein-derived scaffolds, including sterility and pro-inflammatory responses, current practices favor the use of synthetic polymers, such as polycaprolactone (PCL), for generating nanofibrous scaffolds. In this study, we tested the hypothesis that plant protein-derived fibrous scaffolds can provide favorable conditions permissive for the maturation of RPE tissue sheets in vitro. Our natural, soy protein-derived nanofibrous scaffolds exhibited a J-shaped stress-strain curve that more closely resembled the mechanical properties of native tissues than PCL with significantly higher hydrophilicity of the natural scaffolds, favoring in vivo implantation. We then demonstrate that iRPE sheets growing on these soy protein scaffolds are equivalent to iRPE monolayers cultured on synthetic PCL nanofibrous scaffolds. Immunohistochemistry demonstrated RPE-like morphology and functionality with appropriate localization of RPE markers RPE65, PMEL17, Ezrin, and ZO1 and with anticipated histotypic polarization of vascular endothelial growth factor and pigment epithelium-derived growth factor as indicated by enzyme-linked immunosorbent assay. Scanning electron microscopy revealed dense microvilli on the cell surface and homogeneous tight junctional contacts between the cells. Finally, comparative transcriptome analysis in conjunction with principal component analysis demonstrated that iRPE on nanofibrous scaffolds, either natural or synthetic, matured more consistently than on nonfibrous substrates. Taken together, our studies suggest that the maturation of cultured iRPE sheets for subsequent clinical applications might benefit from the use of nanofibrous scaffolds generated from natural proteins. Impact statement Induced retinal pigment epithelium (iRPE) from patient-derived induced pluripotent stem cells (iPSCs) may yield powerful treatments of retinal diseases, including age-related macular degeneration. Recent studies, including early human clinical trials, demonstrate the importance of selecting appropriate biomaterial scaffolds to support tissue-engineered iRPE sheets during implantation. Electrospun scaffolds show particular promise due to their similarity to the structure of the native Bruch's membrane. In this study, we describe the use of electroprocessed nanofibrous soy protein scaffolds to generate polarized sheets of human iPSC-derived iRPE sheets. Our evaluation, including RNA-seq transcriptomics, indicates that these scaffolds are viable alternatives to scaffolds electrospun from synthetic polymers.

Biocompatibility studies of fluorescent diamond particles-(NV)~800nm (part V): in vitro kinetics and in vivo localization in rat liver following long-term exposure

Background

We recently reported on long-term comprehensive biocompatibility and biodistribution study of fluorescent nanodiamond particles (NV)-Z-average 800nm (FNDP-(NV)) in rats. FNDP-(NV) primary deposition was found in the liver, yet liver function tests remained normal.

Purpose

The present study aimed to gain preliminary insights on discrete localization of FNDP-(NV) in liver cells of the hepatic lobule unit and venous micro-vasculature. Kinetics of FDNP-(NV) uptake into liver cells surrogates in culture was conducted along with cell cytokinesis as markers of cells' viability.

Methods

Preserved liver specimens from a pilot consisting of two animals which were stained for cytoskeletal elements (fluorescein-isothiocyanate-phalloidin) were examined for distribution of FNDP-(NV) by fluorescent microscopy (FM) and Confocal-FM (CFM) using near infra-red fluorescence (NIR). Hepatocellular carcinoma cells (HepG-2) and human umbilical vein endothelial cells (HUVEC) were cultured with FNDP-(NV) and assayed for particle uptake and location using spectrophotometric technology and microscopy.

Results

HepG-2 and HUVEC displayed rapid (<30 mins) onset and concentration-dependent FNDP-(NV) internalization and formation of peri-nuclear corona. FM/CFM of liver sections revealed FNDP-(NV) presence throughout the hepatic lobules structures marked by spatial distribution, venous microvascular spaces and parenchyma and non-parenchyma cells.

Conclusion

The robust presence of FNDP-(NV) throughout the hepatic lobules including those internalized within parenchyma cells and agglomerates in the liver venous micro-circulation were not associated with macro or micro histopathological signs nor vascular lesions. Cells cultures indicated normal cytokinesis in cells containing FNDP-(NV) agglomerates. Liver parenchyma cells and the liver microcirculation remain agnostic to presence of FNDP-(NV) in the sinusoids or internalized in the hepatic cells.

An Air Bubble-Isolating Rotating Wall Vessel Bioreactor for Improved Spheroid/Organoid Formation

IMPACT STATEMENT

The rotating wall vessel (RWV) bioreactor is a powerful tool for the generation of sizeable, faster-growing organoids. However, the ideal, low-shear, modeled microgravity environment in the RWV is frequently disrupted by the formation of bubbles, a critical but understated failure mode. To address this, we have designed and fabricated a novel, modified RWV bioreactor capable of continuously removing bubbles while providing optimal fluid dynamics. We validated the capacity of this device with computational and empirical studies. We anticipate that our novel bioreactor will be more consistent and easier to use and may fill a unique and unmet niche in the burgeoning field of organoids.

Long-term biocompatibility of fluorescent diamonds-(NV)-Z~800 nm in rats: survival, morbidity, histopathology, particle distribution and excretion studies (part IV)

Background

Thromboembolic events are a major cause of heart attacks and strokes. However, diagnosis of the location of high risk vascular clots is hampered by lack of proper technologies for their detection. We recently reported on bio-engineered fluorescent diamond-(NV)-Z~800nm (FNDP-(NV)) conjugated with bitistatin (Bit) and proven its ability to identify iatrogenic blood clots in the rat carotid artery in vivo by Near Infra-Red (NIR) monitored by In Vivo Imaging System (IVIS).

Purpose

The objective of the present research was to assess the in vivo biocompatibility of FNDP-(NV)-Z~800nm infused intravenously to rats. Multiple biological variables were assessed along this 12 week study commissioned in anticipation of regulatory requirements for a long-term safety assessment.

Methods

Rats were infused under anesthesia with aforementioned dose of the FNDP-(NV), while equal number of animals served as control (vehicle treated). Over the 12 week observation period rats were tested for thriving, motor, sensory and cognitive functions. At the termination of study, blood samples were obtained under anesthesia for comprehensive hematology and biochemical assays. Furthermore, 6 whole organs (liver, spleen, brain, heart, lung and kidney) were collected and examined ex vivo for FNDP-NV) via NIR monitored by IVIS and histochemical inspection.

Results

All animals survived, thrived (no change in body and organ growth). Neuro-behavioral functions remain intact. Hematology and biochemistry (including liver and kidney functions) were normal. Preferential FNDP-(NV) distribution identified the liver as the main long-term repository. Certified pathology reports indicated no outstanding of finding in all organs.

Conclusion

The present study suggests outstanding biocompatibility of FNDP-(NV)-Z~800nm after long-term exposure in the rat.

Altered Amniotic Fluid Levels of Hyaluronic Acid in Fetal Rats with Myelomeningocele: Understanding Spinal Cord Injury

Myelomeningocele (MMC) is a devastating congenital neural tube defect that results in the exposure of spinal cord to the intrauterine environment, leading to secondary spinal cord injury and severe impairment. Although the mechanisms underlying the secondary pathogenesis are clinically relevant, the exact cause of in utero-acquired spinal cord damage remains unclear. The objective of this study was to determine whether the hyaluronic acid (HA) concentration in amniotic fluid (AF) in the retinoic acid-induced model of MMC is different from that in normal controls and whether these differences could have an impact on the viscosity of AF. Our data shows that the concentration of HA in AF samples from fetuses with MMC (MMC-AF) and normal control samples (Norm-AF) were not significantly different at embryonic day 18 (E18) and E20. Thereafter, the HA concentration significantly increased in Norm-AF but not in MMC-AF. Compared with Norm-AF, the concentration of HA in MMC-AF and the viscosity of MMC-AF were significantly lower at E21. Agarose gel electrophoresis confirmed a significant reduction in the HA level of MMC-AF compared with Norm-AF at E21. No HA-degrading activity was detected in MMC-AF. In summary, we identified a deficiency in the AF level of HA and the viscosity of AF in fetal rats with MMC. These data are discussed in relation to a potential role the reduction in the AF viscosity due to the low level of HA may play in the exacerbating effects of mechanical trauma on spinal cord damage at the MMC lesion site.

Gradient porous fibrous scaffolds: a novel approach to improving cell penetration in electrospun scaffolds

Electrospinning is an increasingly popular technique to generate 3D fibrous tissue scaffolds that mimic the submicron sized fibers of extracellular matrices. A major drawback of electrospun scaffolds is the small interfibrillar pore size, which normally prevents cellular penetration in between fibers. In this study, we introduced a novel process, based on electrospinning, to manufacture a unique gradient porous fibrous (GPF) scaffold from soy protein isolate (SPI). The pore sizes in the GPF scaffolds gradually increase from one side of the scaffold to the other, ranging from 7.8 ± 2.5 μm in the small pore side, 21.4 ± 10.3 μm in the mid layer to 58.0 ± 23.6 μm in the large pore side. The smallest pores of the GPF scaffolds appeared to be somewhat larger than those in conventionally electrospun SPI scaffolds (4.2 ± 1.3 μm). Hydrated GPF scaffolds exhibited J-shaped stress-strain curves, reminiscent of those for soft biological scaffolds. Attachment, spreading, and proliferation of human dermal fibroblasts (HDFB) were supported on both the small and the large pore sides of the GPF scaffolds. Cultured HDFB and murine RAW 264.7 macrophages penetrated significantly deeper (98.7 ± 24.2 μm and 53.3 ± 9.6 μm, respectively) into the larger pores than when seeded onto the small pore side of GPF scaffolds (22.8 ± 6.2 μm and 25.7 ± 7.3 μm) and control SPI scaffolds. (11.3 ± 3.8 μm and 15.3 ± 3.1 μm). This study introduces a novel fabrication technique, which, by convergence of several biofabrication technologies, produces scaffolds with enhanced cellular penetration.

Pilot study on biocompatibility of fluorescent nanodiamond-(NV)-Z~800 particles in rats: safety, pharmacokinetics, and bio-distribution (part III)

Introduction

We hereby report on studies aimed to characterize safety, pharmacokinetics, and bio-distribution of fluorescent nanodiamond particles (NV)-Z~800 (FNDP-(NV)) administered to rats by intravenous infusion in a single high dose.

Methods

Broad scale biological variables were monitored following acute (90 minutes) and subacute (5 or 14 days) exposure to FNDP-(NV). Primary endpoints included morbidity and mortality, while secondary endpoints focused on hematology and clinical biochemistry biomarkers. Particle distribution (liver, spleen, lung, heart, and kidney) was assessed by whole organ near infrared imaging using an in vivo imaging system. This was validated by the quantification of particles extracted from the same organs and visualized by fluorescent and scanning electron microscopy. FNDP-(NV)-treated rats showed no change in morbidity or mortality and preserved normal motor and sensory function, as assessed by six different tests.

Results

Blood cell counts and plasma biochemistry remained normal. The particles were principally distributed in the liver and spleen. The liver particle load accounted for 51%, 24%, and 18% at 90 minutes, 5 days, and 14 days, respectively. A pilot study of particle clearance from blood indicated 50% clearance 33 minutes following the end of particle infusion.

Conclusion

We concluded that systemic exposure of rats to a single high dose of FDNP-(NV)-Z~800 (60 mg/kg) appeared to be safe and well tolerated over at least 2 weeks. These data suggest that FNDP-(NV) should proceed to preclinical development in the near future.

A Bilayered Poly (Lactic-Co-Glycolic Acid) Scaffold Provides Differential Cues for the Differentiation of Dental Pulp Stem Cells

IMPACT STATEMENT

In this article we used an FDA-approved biodegradable biomaterial, poly (lactic-co-glycolic acid) (PLGA 75:25) to generate a bilayered scaffold with the capacity to induce differential, layer-specific dentinogenic differentiation of dental pulp stem cells (DPSCs) in vitro. We surmise that such a scaffold can be used in conjunction with current regenerative endodontic procedures to help regenerating a physiologic dentin-pulp complex in vivo. We hypothesize that our scaffold in conjunction with DPSCs will advance current regenerative endodontics by restoring dentin and initiating the innervation and revascularization of the pulp.

Abstract WP56: Imaging Intra-Carotid Thrombosis Using Near InfraRed Fluorescent-NanoDiamond Particles Bio-engineered With the Disintegrin Bitistatin

Background: Thromboembolism is a major cause of events in carotid artery (CA) disease and predisposes the dissemination of clots to upstream ischemic strokes. Although diagnostic methods are available to define thromboembolic strokes (CT, MRI, etc.), there is no technology to provide ambulatory assessment to ‘content image’ thrombi within the CA bifurcation free of the hospital setting. To address this unmet medical need we bioengineered the joining of the disintegrin bitistatin (Bit) to fluorescent NanoDiamond Particles (F-NDP) in order to bind to and non-invasively image vascular clots. F-NDP-Bit preferentially binds to the human platelet fibrinogen receptor (GPIIB/IIIA). F-NDP-Bit was systematically evaluated for NIR emission capacity in various tissues and demonstrated penetration of NIR fluorescence across distances similar to the distance from the human skin surface to the CA bifurcation.

Methods: In vitro studies were conducted to evaluate binding of F-NDP-Bit to purified human GPIIB/IIIA. Also, the ability of the F-NDP-Bit to bind to vascular clots In Vivo was investigated in rat FeCl3-induced internal CA coagulation.

Results: Using the specific GPIIB/IIIA antagonist lotrafiban, In Vitro specific and concentration-related F-NDP-Bit binding was demonstrated. In Vivo , intravenous administration of F-NDP-Bit during the evolution of FeCl3-induced internal CA thrombosis resulted in the dose-related clot accumulation of F-NDP-Bit that was cross-validated by three independent methods (all measures were significant as described; p < 0.05): ( 1 ) In Situ whole rat imaging via In Vivo Imaging System (IVIS: using Ex 54 nm; Em 695-770 nm); ( 2 ) Ex Vivo whole vessel/clot imaging (Scanning Confocal Microscopy), and ( 3 ) Extract, isolate and quantitate F-NDP-Bit following internal CA clot dissolution (12N HNO3) and direct counting (hemocytometer).

Conclusions: These data indicate that F-NDP-Bit might address the need for fast, safe and highly affordable ambulatory imaging of vascular clot burden. Functionalization of F-NDP with selective ligands that can be pathognomonic for many disease situations also could facilitate risk assessment, earlier intervention and preventative medicine.

Vascular thrombus imaging in vivo via near-infrared fluorescent nanodiamond particles bioengineered with the disintegrin bitistatin (Part II)

The aim of this feasibility study was to test the ability of fluorescent nanodiamond particles (F-NDP) covalently conjugated with bitistatin (F-NDP-Bit) to detect vascular blood clots in vivo using extracorporeal near-infrared (NIR) imaging. Specifically, we compared NIR fluorescence properties of F-NDP with N-V (F-NDP_NV) and N-V-N color centers and sizes (100–10,000 nm). Optimal NIR fluorescence and tissue penetration across biological tissues (rat skin, porcine axillary veins, and skin) was obtained for F-NDP_NV with a mean diameter of 700 nm. Intravital imaging (using in vivo imaging system [IVIS]) in vitro revealed that F-NDP_NV-loaded glass capillaries could be detected across 6 mm of rat red-muscle barrier and 12 mm of porcine skin, which equals the average vertical distance of a human carotid artery bifurcation from the surface of the adjacent skin (14 mm). In vivo, feasibility was demonstrated in a rat model of occlusive blood clots generated using FeCl₃ in the carotid artery bifurcation. Following systemic infusions of F-NDP_NV-Bit (3 or 15 mg/kg) via the external carotid artery or femoral vein (N=3), presence of the particles in the thrombi was confirmed both in situ via IVIS, and ex vivo via confocal imaging. The presence of F-NDP_NV in the vascular clots was further confirmed by direct counting of fluorescent particles extracted from clots following tissue solubilization. Our data suggest that F-NDP_NV-Bit associate with vascular blood clots, presumably by binding of F-NDP_NV-Bit to activated platelets within the blood clot. We posit that F-NDP_NV-Bit could serve as a noninvasive platform for identification of vascular thrombi using NIR energy monitored by an extracorporeal device.

Bitistatin-functionalized fluorescent nanodiamond particles specifically bind to purified human platelet integrin receptor αIIbβ3 and activated platelets

Thromboembolic events (TEE) underwrite key causes of death in developed countries. While advanced imaging technologies such as computed tomography scans serve to diagnose blood clots during acute cardiovascular events, no such technology is available in routine primary care for TEE risk assessment. Here, we describe an imaging platform technology based on bioengineered fluorescent nanodiamond particles (F-NDPs) functionalized with bitistatin (Bit), a disintegrin that specifically binds to the α_IIbβ₃ integrin, platelet fibrinogen receptor (PFR) on activated platelets. Covalent linkage of purified Bit to F-NDP was concentration-dependent and saturable, as validated by enzyme-linked immunosorbent assay using specific anti-Bit antibodies. F-NDP-Bit interacted with purified PFR, either in immobilized or soluble form. Lotrafiban, a nonpeptide, α_IIbβ₃ receptor antagonist, specifically blocked F-NDP-Bit-PFR complex formation. Moreover, F-NDP-Bit specifically binds to activated platelets incorporated into a clot generated by thrombin-activated rat platelet-rich plasma (PRP). Our results suggest that engineered F-NDP-Bit particles could serve as noninvasive, "real-time" optical diagnostics for clots present in blood vessels.

Calcium binding-mediated sustained release of minocycline from hydrophilic multilayer coatings targeting infection and inflammation

Infection and inflammation are common complications that seriously affect the functionality and longevity of implanted medical implants. Systemic administration of antibiotics and anti-inflammatory drugs often cannot achieve sufficient local concentration to be effective, and elicits serious side effects. Local delivery of therapeutics from drug-eluting coatings presents a promising solution. However, hydrophobic and thick coatings are commonly used to ensure sufficient drug loading and sustained release, which may limit tissue integration and tissue device communications. A calcium-mediated drug delivery mechanism was developed and characterized in this study. This novel mechanism allows controlled, sustained release of minocycline, an effective antibiotic and anti-inflammatory drug, from nanoscale thin hydrophilic polyelectrolyte multilayers for over 35 days at physiologically relevant concentrations. pH-responsive minocycline release was observed as the chelation between minocycline and Ca(2+) is less stable at acidic pH, enabling 'smart' drug delivery in response to infection and/or inflammation-induced tissue acidosis. The release kinetics of minocycline can be controlled by varying initial loading, Ca(2+) concentration, and Ca(2+) incorporation into different layers, enabling facile development of implant coatings with versatile release kinetics. This drug delivery platform can potentially be used for releasing any drug that has high Ca(2+) binding affinity, enabling its use in a variety of biomedical applications.

Distribution of tight junction proteins in adult human salivary glands

Tight junctions (TJs) are an essential structure of fluid-secreting cells, such as those in salivary glands. Three major families of integral membrane proteins have been identified as components of the TJ: claudins, occludin, and junctional adhesion molecules (JAMs), plus the cytosolic protein zonula occludens (ZO). We have been working to develop an orally implantable artificial salivary gland that would be suitable for treating patients lacking salivary parenchymal tissue. To date, little is known about the distribution of TJ proteins in adult human salivary cells and thus what key molecular components might be desirable for the cellular component of an artificial salivary gland device. Therefore, the aim of this study was to determine the distribution of TJ proteins in human salivary glands. Salivary gland samples were obtained from 10 patients. Frozen and formalin-fixed paraffin-embedded sections were stained using IHC methods. Claudin-1 was expressed in ductal, endothelial, and approximately 25% of serous cells. Claudins-2, -3, and -4 and JAM-A were expressed in both ductal and acinar cells, whereas claudin-5 was expressed only in endothelial cells. Occludin and ZO-1 were expressed in acinar, ductal, and endothelial cells. These results provide new information on TJ proteins in two major human salivary glands and should serve as a reference for future studies to assess the presence of appropriate TJ proteins in a tissue-engineered human salivary gland.

Primary culture of polarized human salivary epithelial cells for use in developing an artificial salivary gland

Therapeutic irradiation for head and neck cancer, and the autoimmune disease Sjogren's syndrome, lead to loss of salivary parenchyma. They are the two main causes of irreversible salivary gland hypofunction. Such patients cannot produce adequate levels of saliva, leading to considerable morbidity. We are working to develop an artificial salivary gland for such patients. A major problem in this endeavor has been the difficulty in obtaining a suitable autologous cellular component. This article describes a method of culturing and expanding primary salivary cells obtained from human submandibular glands (huSMGs) that is serum free and yields cells that are epithelial in nature. These include morphological (light and transmission electron microscopy [TEM]), protein expression (immunologically positive for ZO-1, claudin-1, and E-cadherin), and functional evidence. Under confocal microscopy, huSMG cells show polarization and appropriately localize tight junction proteins. TEM micrographs show an absence of dense core granules, but confirm the presence of tight and intermediate junctions and desmosomes between the cells. Functional assays showed that huSMG cells have high transepithelial electrical resistance and low rates of paracellular fluid movement. Additionally, huSMG cells show a normal karyotype without any morphological or numerical abnormalities, and most closely resemble striated and excretory duct cells in appearance. We conclude that this culture method for obtaining autologous human salivary cells should be useful in developing an artificial salivary gland.