Comparison of different gene addition strategies to modify placental derived-mesenchymal stromal cells to produce FVIII

Introduction

Placenta-derived mesenchymal cells (PLCs) endogenously produce FVIII, which makes them ideally suited for cell-based fVIII gene delivery. We have previously reported that human PLCs can be efficiently modified with a lentiviral vector encoding a bioengineered, expression/secretion-optimized fVIII transgene (ET3) and durably produce clinically relevant levels of functionally active FVIII. The objective of the present study was to investigate whether CRISPR/Cas9 can be used to achieve location-specific insertion of a fVIII transgene into a genomic safe harbor, thereby eliminating the potential risks arising from the semi-random genomic integration inherent to lentiviral vectors. We hypothesized this approach would improve the safety of the PLC-based gene delivery platform and might also enhance the therapeutic effect by eliminating chromatin-related transgene silencing.

Methods

We used CRISPR/Cas9 to attempt to insert the bioengineered fVIII transgene "lcoET3" into the AAVS1 site of PLCs (CRISPR-lcoET3) and determined their subsequent levels of FVIII production, comparing results with this approach to those achieved using lentivector transduction (LV-lcoET3) and plasmid transfection (Plasmid-lcoET3). In addition, since liver-derived sinusoidal endothelial cells (LSECs) are the native site of FVIII production in the body, we also performed parallel studies in human (h)LSECs).

Results

PLCs and hLSECs can both be transduced (LV-lcoET3) with very high efficiency and produce high levels of biologically active FVIII. Surprisingly, both cell types were largely refractory to CRISPR/Cas9-mediated knockin of the lcoET3 fVIII transgene in the AAVS1 genome locus. However, successful insertion of an RFP reporter into this locus using an identical procedure suggests the failure to achieve knockin of the lcoET3 expression cassette at this site is likely a function of its large size. Importantly, using plasmids, alone or to introduce the CRISPR/Cas9 "machinery", resulted in dramatic upregulation of TLR 3, TLR 7, and BiP in PLCs, compromising their unique immune-inertness.

Discussion

Although we did not achieve our primary objective, our results validate the utility of both PLCs and hLSECs as cell-based delivery vehicles for a fVIII transgene, and they highlight the hurdles that remain to be overcome before primary human cells can be gene-edited with sufficient efficiency for use in cell-based gene therapy to treat HA.

P12.08.A Uncovering the glioblastoma tumor-microenvironment by high-end multiplexing with imaging mass cytometry

Background

Glioblastoma is one of the most aggressive cancers, and hypoxia plays an essential role in its tumor- microenvironment. Tumor-associated microglia and macrophages (TAMs) have been reported to constitute up to 30 % of the cells, a fraction that is even higher in hypoxic areas. Single-cell mRNA sequencing of glioblastoma tumors has revealed vast heterogeneity, but the spatial aspects are not entirely defined yet. The aim of this study was to uncover differences between the hypoxic and normoxic tumor-microenvironment of human glioblastoma by high-end multiplexing with imaging mass cytometry.

Material and Methods

A tissue microarray (TMA) with normoxic and hypoxic areas from 4 IDH-wildtype glioblastomas was prepared based on the hypoxia marker hypoxia-inducing factor 1 alpha (HIF1 alpha). The TMA was stained with 18 metal-tagged antibodies covering TAMs, lymphocytes, immune checkpoints, vessels, tumor cells and proliferation. The Hyperion-CYTOF technology was used to ablate the samples and the images were analyzed by MCD viewer, Visiopharm software, and customized R scripts.

Results

Single-cell analysis of 160 fields covering around 45,000 cells in the glioblastoma microenvironment revealed multiple cellular phenotypes. It was revealed that proliferating TAMs (IBA1+, Ki67+) were more frequent in hypoxia, whereas proliferating vessels (CD34+, Ki67+) were more frequent in normoxia. Additionally, proliferating stem-like tumor cells (OLIG-2+, Ki67+) were more frequent in normoxia regions.

Conclusion

Our study revealed multiple cellular phenotypes in the glioblastoma microenvironment. The TAMs, endothelial and tumor cell phenotypes revealed may play a critical role in glioblastoma biology however this needs to be elucidated in future studies.

Assessment of porphyrogenicity of drugs and chemicals in selected hepatic cell culture models through a fluorescence-based screening assay

Compounds that induce 5-aminolevulinic acid [ALA] synthase-1 and/or cytochromes P-450 may induce acute porphyric attacks in patients with the acute hepatic porphyrias [AHPs]. Currently, there is no simple, robust model used to assess and predict the porphyrogenicity of drugs and chemicals. Our aim was to develop a fluorescence-based in vitro assay for this purpose. We studied four different hepatic cell culture models: HepG2 cells, LMH cells, 3D HepG2 organoids, and 3D organoids of primary liver cells from people without known disease [normal human controls]. We took advantage of the fluorescent properties of protoporphyrin IX [PP], the last intermediate of the heme biosynthesis pathway, performing fluorescence spectrometry to measure the intensity of fluorescence emitted by these cells treated with selected compounds of importance to patients with AHPs. Among the four cell culture models, the LMH cells produced the highest fluorescence readings, suggesting that these cells retain more robust heme biosynthesis enzymes or that the other cell models may have lost their inducibility of ALA synthase-1 [ALAS-1]. Allyl isopropyl acetamide [AIA], a known potent porphyrogen and inducer of ALAS-1, was used as a positive control to help predict porphyrogenicity for tested compounds. Among the tested compounds (acetaminophen, acetylsalicylic acid, β-estradiol, hydroxychloroquine sulfate, alpha-methyldopa, D (-) norgestrel, phenobarbital, phenytoin, sulfamethoxazole, sulfisoxazole, sodium valproate, and valsartan), concentrations greater than 0.314 mM for norgestrel, phenobarbital, phenytoin, and sodium valproate produced fluorescence readings higher than the reading produced by the positive AIA control. Porphyrin accumulation was also measured by HPLC to confirm the validity of the assay. We conclude that LMH cell cultures in multi-well plates are an inexpensive, robust, and simple system to predict the porphyrogenicity of existing or novel compounds that may exacerbate the AHPs.

3D scaffold-free microlivers with drug metabolic function generated by lineage-reprogrammed hepatocytes from human fibroblasts

Generating microliver tissues to recapitulate hepatic function is of increasing importance in tissue engineering and drug screening. But the limited availability of primary hepatocytes and the marked loss of phenotype hinders their application. Human induced hepatocytes (hiHeps) generated by direct reprogramming can address the shortage of primary hepatocytes to make personalized drug prediction possible. Here, we simplify preparation of reprogramming reagents by expressing six transcriptional factors (HNF4A, FOXA2, FOXA3, ATF5, PROX1, and HNF1) from two lentiviral vectors, each expressing three factors. Transducing human fetal and adult fibroblasts with low vector dosage generated human induced hepatocyte-like cells (hiHeps) displaying characteristics of mature hepatocytes and capable of drug metabolism. To mimic the physiologic liver microenvironment and improve hepatocyte function, we prepared 3D scaffold-free microliver spheroids using hiHeps and human liver nonparenchymal cells through self-assembly without exogenous scaffolds. We then introduced the microliver spheroids into a two-organ microfluidic system to examine interactions between hepatocytes and tumor cells. The hiHeps-derived spheroids metabolized the prodrug capecitabine into the active metabolite 5-fluorouracil and induced toxicity in downstream tumor spheroids. Our results demonstrate that hiHeps can be used to make microliver spheroids and combined with a microfluidic system for drug evaluation. Our work could make it possible to use patient-specific hepatocyte-like cells to predict drug efficacy and side effects in various organs from the same patient.

The potential toxic effects of magnesium oxide nanoparticles and valproate on liver tissue

The liver is the main organ responsible for drug and xenobiotic metabolism and detoxification in the body. There are many antiepileptic drugs and nanoparticles that have been reported to cause serious untoward biological responses and hepatotoxicity. The aim of this study is to investigate the potential toxic effect of aspartic acid-coated magnesium oxide nanoparticles (Mg nano) and valproate (valp) using an in vitro three-dimensional (3D) human liver organoid model and an in vivo pentylenetetrazole (PTZ)-induced convulsion model in rats. Here, 3D human liver organoids were treated with valp or valp + Mg nano for 24 h and then incubated with PTZ for an extra 24 h. As the in vivo model, rats were treated with valp, Mg nano, or valp + Mg nano for 4 weeks and then they were treated with PTZ for 24 h. Toxicity in the liver organoids was demonstrated by reduced cell viability, decreased ATP, and increased reactive oxygen species. In the rat convulsion model, results revealed elevated serum alanine aminotransferase and aspartate aminotransferase levels. Both the in vitro and in vivo data demonstrated the potential toxic effects of valp + Mg nano on the liver tissues.

Drug compound screening in single and integrated multi-organoid body-on-a-chip systems

Current practices in drug development have led to therapeutic compounds being approved for widespread use in humans, only to be later withdrawn due to unanticipated toxicity. These occurrences are largely the result of erroneous data generated by in vivo and in vitro preclinical models that do not accurately recapitulate human physiology. Herein, a human primary cell- and stem cell-derived 3D organoid technology is employed to screen a panel of drugs that were recalled from market by the FDA. The platform is comprised of multiple tissue organoid types that remain viable for at least 28 days, in vitro. For many of these compounds, the 3D organoid system was able to demonstrate toxicity. Furthermore, organoids exposed to non-toxic compounds remained viable at clinically relevant doses. Additional experiments were performed on integrated multi-organoid systems containing liver, cardiac, lung, vascular, testis, colon, and brain. These integrated systems proved to maintain viability and expressed functional biomarkers, long-term. Examples are provided that demonstrate how multi-organoid 'body-on-a-chip' systems may be used to model the interdependent metabolism and downstream effects of drugs across multiple tissues in a single platform. Such 3D in vitro systems represent a more physiologically relevant model for drug screening and will likely reduce the cost and failure rate associated with the approval of new drugs.

Vapor-Deposited Ethylbenzene Glasses Approach "Ideal Glass" Density

Spectroscopic ellipsometry was used to characterize vapor-deposited glasses of ethylbenzene (T_g = 115.7 K). For this system, previous calorimetric experiments have established that a transition to the ideal glass state is expected to occur near 101 K (the Kauzmann temperature, T_K) if the low-temperature supercooled liquid has the properties expected based upon extrapolation from above T_g. Ethylbenzene glasses were vapor-deposited at substrate temperatures between 100 (∼0.86 T_g) and 116 K (∼T_g), using deposition rates of 0.02-2.1 nm/s. Down to 103 K, glasses prepared in the limit of low deposition rate have densities consistent with the extrapolated supercooled liquid. The highest density glass is within 0.15% of the density expected for the ideal glass. These results support the hypothesis that the extrapolated properties of supercooled ethylbenzene are correct to within just a few Kelvin of T_K, consistent with the existence of a phase transition to an ideal glass state at T_K.

SAT-035 Small Molecule Allosteric Agonist of Relaxin Receptor Ml290 Demonstrates Antifibrotic Properties in Liver Fibrosis

Fibrosis is an underlying cause of cirrhosis and hepatic failure resulting in end stage liver disease with limited pharmacological therapeutic options. The beneficial effects of relaxin peptide treatment have been demonstrated previously in clinically relevant animal models of liver disease. However, the low stability of the recombinant relaxin peptide in vivo requires continuous intravenous delivery for chronic therapeutic application. We have recently identified a first series of small molecule allosteric biased agonists of the human relaxin receptor RXFP1 which showed efficacy similar to relaxin in several functional assays in vitro. Here we investigated the therapeutic effects of small molecule RXFP1 agonist on activated hepatic stellate cells, the main source of excessive collagen production in liver fibrosis. We have demonstrated that RXFP1 expression is increased in fibrotic mouse liver, specifically in activated hepatic stellate cells. The lead compound, ML290, was selected based on its effects on the expression of the genes involved in fibrosis in primary human stellate cells. RNA-Seq analysis of TGFβ1-activated LX-2 hepatic stellate cells showed that about 500 genes were misregulated by ML290. Gene Ontology analysis demonstrated that ML290 treatment primarily affects extracellular matrix remodeling and cytokine signaling, with expression profiles indicating an antifibrotic effect of ML290. ML290 treatment of human liver organoids with lipopolysaccharide-induced fibrotic phenotype resulted in dramatic reduction of type I collagen. The pharmacokinetics of ML290 in mice after multiple injections demonstrated its high stability in vivo, as evidenced by the sustained concentrations of compound in the liver. The ML290 treatment of mice expressing human RXFP1 gene with carbon tetrachloride-induced liver fibrosis resulted in significantly reduced collagen content, alpha-smooth muscle actin expression and cell proliferation around portal ducts, and the decrease of pro-fibrotic genes’ expression. In summary, ML290, the small molecule agonist of relaxin receptor, has anti-fibrotic effects in liver fibrosis. Funding source: NIH/NIDDK

A human bone marrow mesodermal-derived cell population with hemogenic potential

The presence, within the human bone marrow, of cells with both endothelial and hemogenic potential has been controversial. Herein, we identify, within the human fetal bone marrow, prior to establishment of hematopoiesis, a unique APLNR+, Stro-1+ cell population, co-expressing markers of early mesodermal precursors and/or hemogenic endothelium. In adult marrow, cells expressing similar markers are also found, but at very low frequency. These adult-derived cells can be extensively culture expanded in vitro without loss of potential, they preserve a biased hemogenic transcriptional profile, and, upon in vitro induction with OCT4, assume a hematopoietic phenotype. In vivo, these cells, upon transplantation into a fetal microenvironment, contribute to the vasculature, and generate hematopoietic cells that provide multilineage repopulation upon serial transplantation. The identification of this human somatic cell population provides novel insights into human ontogenetic hematovascular potential, which could lead to a better understanding of, and new target therapies for, malignant and nonmalignant hematologic disorders.

Correction: A human bone marrow mesodermal-derived cell population with hemogenic potential

At the time of publication the funding information was omitted from the article - this has now been corrected in both the HTML and the PDF.

Environmental Toxin Screening Using Human-Derived 3D Bioengineered Liver and Cardiac Organoids

INTRODUCTION

Environmental toxins, such as lead and other heavy metals, pesticides, and other compounds, represent a significant health concern within the USA and around the world. Even in the twenty-first century, a plethora of cities and towns in the U.S. have suffered from exposures to lead in drinking water or other heavy metals in food or the earth, while there is a high possibility of further places to suffer such exposures in the near future.

METHODS

We employed bioengineered 3D human liver and cardiac organoids to screen a panel of environmental toxins (lead, mercury, thallium, and glyphosate), and charted the response of the organoids to these compounds. Liver and cardiac organoids were exposed to lead (10 µM-10 mM), mercury (200 nM-200 µM), thallium (10 nM-10 µM), or glyphosate (25 µM-25 mM) for a duration of 48 h. The impacts of toxin exposure were then assessed by LIVE/DEAD viability and cytotoxicity staining, measuring ATP activity and determining IC50 values, and determining changes in cardiac organoid beating activity.

RESULTS

As expected, all of the toxins induced toxicity in the organoids. Both ATP and LIVE/DEAD assays showed toxicity in both liver and cardiac organoids. In particular, thallium was the most toxic, with IC50 values of 13.5 and 1.35 µM in liver and cardiac organoids, respectively. Conversely, glyphosate was the least toxic of the four compounds, with IC50 values of 10.53 and 10.85 mM in liver and cardiac organoids, respectively. Additionally, toxins had a negative influence on cardiac organoid beating activity as well. Thallium resulting in the most significant decreases in beating rate, followed by mercury, then glyphosate, and finally, lead. These results suggest that the 3D organoids have significant utility to be deployed in additional toxicity screening applications, and future development of treatments to mitigate exposures.

CONCLUSION

3D organoids have significant utility to be deployed in additional toxicity screening applications, such as future development of treatments to mitigate exposures, drug screening, and environmental toxin detection.

Bioprinting 3D microfibrous scaffolds for engineering endothelialized myocardium and heart-on-a-chip

Engineering cardiac tissues and organ models remains a great challenge due to the hierarchical structure of the native myocardium. The need of integrating blood vessels brings additional complexity, limiting the available approaches that are suitable to produce integrated cardiovascular organoids. In this work we propose a novel hybrid strategy based on 3D bioprinting, to fabricate endothelialized myocardium. Enabled by the use of our composite bioink, endothelial cells directly bioprinted within microfibrous hydrogel scaffolds gradually migrated towards the peripheries of the microfibers to form a layer of confluent endothelium. Together with controlled anisotropy, this 3D endothelial bed was then seeded with cardiomyocytes to generate aligned myocardium capable of spontaneous and synchronous contraction. We further embedded the organoids into a specially designed microfluidic perfusion bioreactor to complete the endothelialized-myocardium-on-a-chip platform for cardiovascular toxicity evaluation. Finally, we demonstrated that such a technique could be translated to human cardiomyocytes derived from induced pluripotent stem cells to construct endothelialized human myocardium. We believe that our method for generation of endothelialized organoids fabricated through an innovative 3D bioprinting technology may find widespread applications in regenerative medicine, drug screening, and potentially disease modeling.

Effect of Paroven on Skin Oxygenation in Patients with Varicose Veins

A double blind placebo-controlled clinical trial was undertaken to investigate the effect of 500 mg bd of Paroven taken for four weeks on the tissue oxygenation, ankle oedema and calf pump function of 48 patients with chronic venous disease.

There was no evidence that Paroven reduced ankle swelling or improved calf pump function, but it did cause a significant improvement in transcutaneous oxygen levels measured in the calf skin of the ulcer hearing area ( p = 0.026) which was confirmed when the oxygen levels of the active and placebo treated groups were compared at the end of four weeks treatment ( p = 0.02). This improvement in tissue oxygenation may be the result of alterations in the capillary exchange produced by the drug and may account for the symptomatic benefit associated with its use.

Bioprinting Cellularized Constructs Using a Tissue-specific Hydrogel Bioink

Bioprinting has emerged as a versatile biofabrication approach for creating tissue engineered organ constructs. These constructs have potential use as organ replacements for implantation in patients, and also, when created on a smaller size scale as model "organoids" that can be used in in vitro systems for drug and toxicology screening. Despite development of a wide variety of bioprinting devices, application of bioprinting technology can be limited by the availability of materials that both expedite bioprinting procedures and support cell viability and function by providing tissue-specific cues. Here we describe a versatile hyaluronic acid (HA) and gelatin-based hydrogel system comprised of a multi-crosslinker, 2-stage crosslinking protocol, which can provide tissue specific biochemical signals and mimic the mechanical properties of in vivo tissues. Biochemical factors are provided by incorporating tissue-derived extracellular matrix materials, which include potent growth factors. Tissue mechanical properties are controlled combinations of PEG-based crosslinkers with varying molecular weights, geometries (linear or multi-arm), and functional groups to yield extrudable bioinks and final construct shear stiffness values over a wide range (100 Pa to 20 kPa). Using these parameters, hydrogel bioinks were used to bioprint primary liver spheroids in a liver-specific bioink to create in vitro liver constructs with high cell viability and measurable functional albumin and urea output. This methodology provides a general framework that can be adapted for future customization of hydrogels for biofabrication of a wide range of tissue construct types.

A hydrogel bioink toolkit for mimicking native tissue biochemical and mechanical properties in bioprinted tissue constructs

Advancement of bioprinting technology is limited by the availability of materials that both facilitate bioprinting logistics as well as support cell viability and function by providing tissue-specific cues. Herein we describe a modular hyaluronic acid (HA) and gelatin-based hydrogel toolbox comprised of a 2-crosslinker, 2-stage polymerization technique, and the capability to provide tissue specific biochemically and mechanically accurate signals to cells within biofabricated tissue constructs. First, we prepared and characterized several tissue-derived decellularized extracellular matrix-based solutions, which contain complex combinations of growth factors, collagens, glycosaminoglycans, and elastin. These solutions can be incorporated into bioinks to provide the important biochemical cues of different tissue types. Second, we employed combinations of PEG-based crosslinkers with varying molecular weights, geometries (linear, 4-arm, and 8-arm), and functional groups to yield hydrogel bioinks that supported extrusion bioprinting and the capability to achieve final construct shear stiffness values ranging from approximately 100 Pa to 20 kPa. Lastly, we integrated these hydrogel bioinks with a 3-D bioprinting platform, and validated their use by bioprinting primary liver spheroids in a liver-specific bioink to create in vitro liver constructs with high cell viability and measurable functional albumin and urea output. This hydrogel bioink system has the potential to be a versatile tool for biofabrication of a wide range of tissue construct types.

STATEMENT OF SIGNIFICANCE

Biochemical and mechanical factors both have important implications in guiding the behavior of cells in vivo, yet both realms are rarely considered together in the context of biofabrication in vitro tissue construct models. We describe a modular hydrogel system that (1) facilitates extrusion bioprinting of cell-laden hydrogels, (2) incorporates tissue-specific factors derived from decellularized tissue extracellular matrix, thus mimicking biochemical tissue profile, and (3) allows control over mechanical properties to mimic the tissue stiffness. We believe that employing this technology to attend to both the biochemical and mechanical profiles of tissues, will allow us to more accurately recapitulate the in vivo environment of tissues while creating functional 3-D in vitro tissue constructs that can be used as disease models, personalized medicine, and in vitro drug and toxicology screening systems.

Alterations in primary motor cortex neurotransmission and gene expression in hemi-parkinsonian rats with drug-induced dyskinesia

Treatment of Parkinson's disease (PD) with dopamine replacement relieves symptoms of poverty of movement, but often causes drug-induced dyskinesias. Accumulating clinical and pre-clinical evidence suggests that the primary motor cortex (M1) is involved in the pathophysiology of PD and that modulating cortical activity may be a therapeutic target in PD and dyskinesia. However, surprisingly little is known about how M1 neurotransmitter tone or gene expression is altered in PD, dyskinesia or associated animal models. The present study utilized the rat unilateral 6-hydroxydopamine (6-OHDA) model of PD/dyskinesia to characterize structural and functional changes taking place in M1 monoamine innervation and gene expression. 6-OHDA caused dopamine pathology in M1, although the lesion was less severe than in the striatum. Rats with 6-OHDA lesions showed a PD motor impairment and developed dyskinesia when given L-DOPA or the D1 receptor agonist, SKF81297. M1 expression of two immediate-early genes (c-Fos and ARC) was strongly enhanced by either L-DOPA or SKF81297. At the same time, expression of genes specifically involved in glutamate and GABA signaling were either modestly affected or unchanged by lesion and/or treatment. We conclude that M1 neurotransmission and signal transduction in the rat 6-OHDA model of PD/dyskinesia mirror features of human PD, supporting the utility of the model to study M1 dysfunction in PD and the elucidation of novel pathophysiological mechanisms and therapeutic targets.

Side effect profile of 5-HT treatments for Parkinson's disease and L-DOPA-induced dyskinesia in rats

BACKGROUND AND PURPOSE

Treatment of Parkinson's disease (PD) with L-DOPA eventually causes abnormal involuntary movements known as dyskinesias in most patients. Dyskinesia can be reduced using compounds that act as direct or indirect agonists of the 5-HT1 A receptor, but these drugs have been reported to worsen PD features and are known to produce '5-HT syndrome', symptoms of which include tremor, myoclonus, rigidity and hyper-reflexia.

EXPERIMENTAL APPROACH

Sprague-Dawley rats were given unilateral nigrostriatal dopamine lesions with 6-hydroxydopamine. Each of the following three purportedly anti-dyskinetic 5-HT compounds were administered 15 min before L-DOPA: the full 5-HT1 A agonist ±-8-hydroxy-2-dipropylaminotetralin (±8-OH-DPAT), the partial 5-HT1 A agonist buspirone or the 5-HT transporter inhibitor citalopram. After these injections, animals were monitored for dyskinesia, 5-HT syndrome, motor activity and PD akinesia.

KEY RESULTS

Each 5-HT drug dose-dependently reduced dyskinesia by relatively equal amounts (±8-OH-DPAT ≥ citalopram ≥ buspirone), but 5-HT syndrome was higher with ±8-OH-DPAT, lower with buspirone and not present with citalopram. Importantly, with or without L-DOPA, all three compounds provided an additional improvement of PD akinesia. All drugs tempered the locomotor response to L-DOPA suggesting dyskinesia reduction, but vertical rearing was reduced with 5-HT drugs, potentially reflecting features of 5-HT syndrome.

CONCLUSIONS AND IMPLICATIONS

The results suggest that compounds that indirectly facilitate 5-HT1 A receptor activation, such as citalopram, may be more effective therapeutics than direct 5-HT1 A receptor agonists because they exhibit similar anti-dyskinesia efficacy, while possessing a reduced side effect profile.

Amniotic fluid stem cells improve survival and enhance repair of damaged intestine in necrotising enterocolitis via a COX-2 dependent mechanism

OBJECTIVE

Necrotising enterocolitis (NEC) remains one of the primary causes of morbidity and mortality in neonates and alternative strategies are needed. Stem cells have become a therapeutic option for other intestinal diseases, which share some features with NEC. We tested the hypothesis that amniotic fluid stem (AFS) cells exerted a beneficial effect in a neonatal rat model of NEC.

DESIGN

Rats intraperitoneally injected with AFS cells and their controls (bone marrow mesenchymal stem cells, myoblast) were analysed for survival, behaviour, bowel imaging (MRI scan), histology, bowel absorption and motility, immunofluorescence for AFS cell detection, degree of gut inflammation (myeloperoxidase and malondialdehyde), and enterocyte apoptosis and proliferation.

RESULTS

AFS cells integrated in the bowel wall and improved rat survival and clinical conditions, decreased NEC incidence and macroscopic gut damage, improved intestinal function, decreased bowel inflammation, increased enterocyte proliferation and reduced apoptosis. The beneficial effect was achieved via modulation of stromal cells expressing cyclooxygenase 2 in the lamina propria, as shown by survival studies using selective and non-selective cyclooxygenase 2 inhibitors. Interestingly, AFS cells differentially expressed genes of the Wnt/β-catenin pathway, which regulate intestinal epithelial stem cell function and cell migration and growth factors known to maintain gut epithelial integrity and reduce mucosal injury.

CONCLUSIONS

We demonstrated here for the first time that AFS cells injected in an established model of NEC improve survival, clinical status, gut structure and function. Understanding the mechanism of this effect may help us to develop new cellular or pharmacological therapies for infants with NEC.

Interactions of protamine with the marine bacterium, Pseudoalteromonas sp. NCIMB 2021

Pseudoalteromonas sp. NCIMB 2021 (NCIMB 2021) was grown in synthetic seawater (SSW) containing pyruvate, in the presence (SSW(++) ) and absence (SSW(-) ) of divalent cations. Cultures contained single cells. Addition of the cationic antibacterial peptide (CAP), protamine, did not inhibit, but rather increased, the growth of NCIMB 2021 in SSW(++) and caused the bacteria to grow in chains. Bacterial growth was assessed using turbidity, cell counts and the sodium salt of resazurin. In SSW(-) , NCIMB 2021 was no longer resistant to protamine. The minimum inhibitory concentration (MIC) was 5 mg ml(-1) .

SIGNIFICANCE AND IMPACT OF THE STUDY

Protamine is a cationic antimicrobial peptide (CAP), which is active against a variety of bacteria. This is the first in-depth study of the interaction of protamine with a marine bacterium, Pseudoalteromonas sp. NCIMB 2021. Our results show that protamine is only active in seawater in the absence of divalent cations. In the presence of the divalent cations, Mg(2+) and Ca(2+) , protamine enhances the growth of Pseudoalteromonas sp. NCIMB 2021 and produces chains rather than individual cells. These are important considerations when deciding on applications for protamine and in terms of understanding its mechanism of action.

Effect of intermittent PTH (1-34) on posterolateral spinal fusion with iliac crest bone graft in an ovariectomized rat model

SUMMARY

Intermittent treatment with high-dose parathyroid hormone (PTH) enhances the quantity and quality of the fusion callus and reduces healing time of posterolateral spinal fusion with autologous iliac bone grafts in ovariectomized osteoporotic female Sprague-Dawley rats. Intermittent PTH (1-34) could be an appropriate adjunctive therapy for osteoporotic patients undergoing posterolateral intertransverse process fusion.

INTRODUCTION

The study was designed to test the hypothesis that intermittent administration of PTH improves spinal fusion rates in a randomized controlled, ovariectomized osteoporotic rat spinal fusion model.

METHODS

Thirty-six 10-week-old Sprague-Dawley rats were ovariectomized and underwent bilateral posterolateral L4-L5 spinal fusion with autologous iliac bone graft 6 weeks later. The experimental (PTH) group (18 rats) received daily subcutaneously administered injections of PTH (1-34) at 30 μg/kg/day starting on the day of operation. The control group (18 rats) received a subcutaneously administered injection of normal saline of the same volume. Nine rats from each group were sacrificed at 4 and 6 weeks. After sacrifice, the L4-L5 vertebral segments were removed and analyzed by plain radiographs, μ-CT, histomorphometry, and serum bone metabolism marker.

RESULTS

The PTH group had a significantly higher fusion rate and X-ray fusion score than the control group at 4 and 6 weeks (p < 0.05). μ-CT and histological analysis showed that the fusion bone volume and cortical thickness for the PTH group were significantly higher than those for the control group at 4 and 6 weeks (p < 0.05). Metabolic marker analysis also showed significant difference between the two groups. The serum osteocalcin was significantly higher in the PTH group at 4 and 6 weeks, and levels of N-terminal peptide of type I collagen were significantly higher at 4 weeks (p < 0.05).

CONCLUSION

Intermittent treatment with high-dose PTH enhances the quantity of the fusion callus and reduces the healing time of posterolateral spinal fusion with autologous iliac bone grafts in ovariectomized osteoporotic female Sprague-Dawley rats.

Novel frem1-related mouse phenotypes and evidence of genetic interactions with gata4 and slit3

The FRAS1-related extracellular matrix 1 (FREM1) gene encodes an extracellular matrix protein that plays a critical role in the development of multiple organ systems. In humans, recessive mutations in FREM1 cause eye defects, congenital diaphragmatic hernia, renal anomalies and anorectal malformations including anteriorly placed anus. A similar constellation of findings-microphthalmia, cryptophthalmos, congenital diaphragmatic hernia, renal agenesis and rectal prolapse-have been described in FREM1-deficient mice. In this paper, we identify a homozygous Frem1 missense mutation (c.1687A>T, p.Ile563Phe) in an N-ethyl-N-nitrosourea (ENU)-derived mouse strain, crf11, with microphthalmia, cryptophthalmos, renal agenesis and rectal prolapse. This mutation affects a highly conserved residue in FREM1's third CSPG domain. The p.Ile563Phe change is predicted to be deleterious and to cause decreased FREM1 protein stability. The crf11 allele also fails to complement the previously described eyes2 allele of Frem1 (p.Lys826*) providing further evidence that the crf11 phenotype is due to changes affecting Frem1 function. We then use mice bearing the crf11 and eyes2 alleles to identify lung lobulation defects and decreased anogenital distance in males as novel phenotypes associated with FREM1 deficiency in mice. Due to phenotypic overlaps between FREM1-deficient mice and mice that are deficient for the retinoic acid-responsive transcription factor GATA4 and the extracellular matrix protein SLIT3, we also perform experiments to look for in vivo genetic interactions between the genes that encode these proteins. These experiments reveal that Frem1 interacts genetically with Gata4 in the development of lung lobulation defects and with Slit3 in the development of renal agenesis. These results demonstrate that FREM1-deficient mice faithfully recapitulate many of the phenotypes seen in individuals with FREM1 deficiency and that variations in GATA4 and SLIT3 expression modulate some FREM1-related phenotypes in mice.

L-DOPA-induced dysregulation of extrastriatal dopamine and serotonin and affective symptoms in a bilateral rat model of Parkinson's disease

Convergent evidence indicates that raphestriatal serotonin (5-HT) neurons can convert and release dopamine (DA) derived from exogenous administration of the pharmacotherapeutic L-3,4-dihydroxyphenyl-L-alanine (L-DOPA) as a treatment for Parkinson's disease (PD). While aspects of such neuroplasticity may be beneficial, chronic L-DOPA may also modify native 5-HT function, precipitating the appearance prevalent non-motor PD symptoms such as anxiety and depression. To examine this, male Sprague-Dawley rats were rendered parkinsonian with bilateral medial forebrain bundle 6-hydroxydopamine (6-OHDA) infusions and treated for at least 28 days with vehicle or L-DOPA. In the first experiment, striatal, hippocampal, amygdalar, and prefrontal cortex DA and 5-HT levels were examined at various post-treatment time-points. In experiment 2, L-DOPA's effects on DA and 5-HT cell bodies in the substantia nigra pars compacta and dorsal raphe, respectively, were examined. Finally, the effects of L-DOPA on affective behaviors were assessed in locomotor chambers, social interaction, forced swim, and elevated plus maze behavioral tests. Bilateral 6-OHDA lesion induced approximately 80% DA and 30% 5-HT depletion in the striatum compared to sham-lesioned controls, while monoamine levels remained largely unchanged in extrastriatal regions. Tissue levels of DA were increased at the expense of 5-HT levels in parkinsonian rats subjected to chronic L-DOPA injections in all regions sampled, though DA or 5-HT cell bodies were unaffected. Behaviorally, rats could only be tested 24h after their last L-DOPA injection due to severe dyskinesia. Despite this, prior exposure to chronic L-DOPA treatment exerted a pronounced anxiogenic phenotype. Collectively, these results suggest that chronic L-DOPA treatment may interfere with the balance of DA and 5-HT function in affect-related brain regions and could induce and/or exacerbate non-motor symptoms in PD.

Exogenous corticosterone reduces L-DOPA-induced dyskinesia in the hemi-parkinsonian rat: role for interleukin-1beta

While the etiology of Parkinson's disease (PD) remains unknown, there is overwhelming evidence that neuroinflammation plays a critical role in the progressive loss of dopamine (DA) neurons. Because nearly all persons suffering from PD receive l-DOPA, it is surprising that inflammation has not been examined as a potential contributor to the abnormal involuntary movements (AIMs) that occur as a consequence of chronic l-DOPA treatment. As an initial test of this hypothesis, we examined the effects of exogenously administered corticosterone (CORT), an endogenous anti-inflammatory agent, on the expression and development of l-DOPA-induced dyskinesia (LID) in unilateral DA-depleted rats. To do this, male Sprague-Dawley rats received unilateral medial forebrain bundle 6-hydroxydopamine lesions. Three weeks later, l-DOPA primed rats received acute injections of CORT (0-3.75 mg/kg) prior to l-DOPA to assess the expression of LID. A second group of rats was used to examine the development of LID in l-DOPA naïve rats co-treated with CORT and l-DOPA for 2 weeks. AIMs and rotations were recorded. Exogenous CORT dose-dependently attenuated both the expression and development of AIMs without affecting rotations. Real-time reverse-transcription polymerase chain reaction of striatal tissue implicated a role for interleukin-1 (IL-1) beta in these effects as its expression was increased on the lesioned side in rats treated with l-DOPA (within the DA-depleted striatum) and attenuated with CORT. In the final experiment, interleukin-1 receptor antagonist (IL-1ra) was microinjected into the striatum of l-DOPA-primed rats to assess the impact of IL-1 signaling on LID. Intrastriatal IL-1ra reduced the expression of LID without affecting rotations. These findings indicate a novel role for neuroinflammation in the expression of LID, and may implicate the use of anti-inflammatory agents as a potential adjunctive therapy for the treatment of LID.

Inhibition of in-stent restenosis in rabbit iliac arteries with photodynamic therapy

OBJECTIVES

Photodynamic therapy (PDT, the combination of light with a photosensitising drug in the presence of oxygen) inhibits restenosis after angioplasty without stenting. This study assesses the potential of PDT for prevention of in-stent re-stenosis.

DESIGN AND METHODS

Normal rabbits were given the photosensitising agent 5-aminolaevulinic acid (ALA) 60 mg/kg, 3 h prior to endovascular illumination of the iliac artery (635 nm at 50 J/cm(2)) either immediately before or after deployment of an oversized (3 mm diameter) stent. PDT treated arteries were retrieved 3 or 28 days later and assessed for cell counts and vascular morphometry. Control arteries (stent but no PDT) were examined at 28 days.

RESULTS

There were no adverse events and all vessels were patent at the end of the study. At 3 days there was almost complete medial cell ablation when light was delivered before stent deployment (17+/-1 cells/hpf), with little effect when illumination followed stent deployment (184+/-17 cells/hpf, p<0.0001). Twenty-eight days after PDT, the neointimal areas were 1.41+/-0.52 mm(2) (stent with no PDT), 1.24+/-0.54 mm(2) (light after stent) and 0.60+/-0.21 mm(2) (light before stent) (p=0.004).

CONCLUSIONS

PDT before stent deployment caused almost complete medial cell ablation at 3 days with inhibition of in-stent restenosis at 28 days. PDT is worthy of further study as an adjuvant to percutaneous intervention in patients with vascular disease.

Combined intrastriatal dopamine D1 and serotonin 5-HT2 receptor stimulation reveals a mechanism for hyperlocomotion in 6-hydroxydopamine-lesioned rats

Loss of dopaminergic innervation to the striatum increases the sensitivity of dopamine (DA) D1 and serotonin (5-HT) 5-HT2 receptor signaling. Previous work from our laboratory has shown that systemic co-administration of D1 and 5-HT2 receptor agonists leads to the synergistic overexpression of striatal preprotachykinin mRNA levels in the DA-depleted, but not intact animals. In the present study, we examined this mechanism as related to locomotor behavior. Adult male Sprague-Dawley rats were subject to bilateral i.c.v. 6-hydroxydopamine (6-OHDA; 200 microg in 10 microl/side) or vehicle (0.9% saline and 0.1% ascorbic acid). After 3 weeks, rats were tested for locomotor responses to bilateral intrastriatal infusions of vehicle (0.9% NaCl), the D1 agonist SKF82958 [(+/-)6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetra-hydro-(1H)-3-benzazepine hydrobromide; 0.1, 1.0 or 10.0 microg/side], the 5-HT2 agonist DOI [(+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane; 0.1, 1.0 or 10.0 microg/side] or subthreshold doses of DOI and SKF82958 (0.1 microg+0.1 microg in 0.8 microl/side). Rats with DA loss demonstrated supersensitive locomotor responses to SKF82958, but not DOI. Combined administration of subthreshold SKF82958 and DOI doses (0.1 microg+0.1 microg) synergistically increased locomotor behavior only in 6-OHDA-lesioned rats. These effects were blocked by either the D1 antagonist SCH23390 3-methyl-1-phenyl-2,3,4,5-tetrahydro-7-chloro-8-hydroxy-(1H)-3-benzazepine or the 5-HT2 antagonist ritanserin (each 1.0 microg in 0.8 microl/side). The results of this study suggest that the behavioral synergy induced by local co-stimulation of D1 and 5-HT2 receptors within the 6-OHDA-lesioned striatum may lead to hyperkinesias that can occur with continued pharmacological treatment of Parkinson's disease.