Transduction profiles in minipig following MRI guided delivery of AAV-5 into thalamic and corona radiata areas

BACKGROUND

As a step towards clinical use of AAV-mediated gene therapy, brains of large animals are used to settle delivery parameters as most brain connections, and relative sizes in large animals and primates, are reasonably common. Prior to application in the clinic, approaches that have shown to be successful in rodent models are tested in larger animal species, such as dogs, non-human primates, and in this case, minipigs.

NEW METHOD

We evaluated alternate delivery routes to target the basal ganglia by injections into the more superficial corona radiata, and, deeper into the brain, the thalamus. Anatomically known connections can be used to predict the expression of the transgene following infusion of AAV5. For optimal control over delivery of the vector with regards to anatomical location in the brain and spread in the tissue, we have used magnetic resonance image-guided convection-enhanced diffusion delivery.

RESULTS

While the transduction of the cortex was observed, only partial transduction of the basal ganglia was achieved via the corona radiata. Thalamic administration, on the other hand, resulted in widespread transduction from the midbrain to the frontal cortex COMPARISON WITH EXISTING METHODS: Compared to other methods, such as delivery directly to the striatum, thalamic injection may provide an alternative when for instance, injection into the basal ganglia directly is not feasible.

CONCLUSIONS

The study results suggest that thalamic administration of AAV5 has significant potential for indications where the transduction of specific areas of the brain is required.

Advancement in Nanostructure-Based Tissue-Engineered Biomaterials for Retinal Degenerative Diseases

The review intends to overview a wide range of nanostructured natural, synthetic and biological membrane implants for tissue engineering to help in retinal degenerative diseases. Herein, we discuss the transplantation strategies and the new development of material in combination with cells such as induced pluripotent stem cells (iPSC), mature retinal cells, adult stem cells, retinal progenitors, fetal retinal cells, or retinal pigment epithelial (RPE) sheets, etc. to be delivered into the subretinal space. Retinitis pigmentosa and age-related macular degeneration (AMD) are the most common retinal diseases resulting in vision impairment or blindness by permanent loss in photoreceptor cells. Currently, there are no therapies that can repair permanent vision loss, and the available treatments can only delay the advancement of retinal degeneration. The delivery of cell-based nanostructure scaffolds has been presented to enrich cell survival and direct cell differentiation in a range of retinal degenerative models. In this review, we sum up the research findings on different types of nanostructure scaffolds/substrate or material-based implants, with or without cells, used to deliver into the subretinal space for retinal diseases. Though, clinical and pre-clinical trials are still needed for these transplants to be used as a clinical treatment method for retinal degeneration.

Widespread and sustained target engagement in Huntington's disease minipigs upon intrastriatal microRNA-based gene therapy

Huntingtin (HTT)-lowering therapies hold promise to slow down neurodegeneration in Huntington's disease (HD). Here, we assessed the translatability and long-term durability of recombinant adeno-associated viral vector serotype 5 expressing a microRNA targeting human HTT (rAAV5-miHTT) administered by magnetic resonance imaging-guided convention-enhanced delivery in transgenic HD minipigs. rAAV5-miHTT (1.2 × 10¹³ vector genome (VG) copies per brain) was successfully administered into the striatum (bilaterally in caudate and putamen), using age-matched untreated animals as controls. Widespread brain biodistribution of vector DNA was observed, with the highest concentration in target (striatal) regions, thalamus, and cortical regions. Vector DNA presence and transgene expression were similar at 6 and 12 months after administration. Expression of miHTT strongly correlated with vector DNA, with a corresponding reduction of mutant HTT (mHTT) protein of more than 75% in injected areas, and 30 to 50% lowering in distal regions. Translational pharmacokinetic and pharmacodynamic measures in cerebrospinal fluid (CSF) were largely in line with the effects observed in the brain. CSF miHTT expression was detected up to 12 months, with CSF mHTT protein lowering of 25 to 30% at 6 and 12 months after dosing. This study demonstrates widespread biodistribution, strong and durable efficiency of rAAV5-miHTT in disease-relevant regions in a large brain, and the potential of using CSF analysis to determine vector expression and efficacy in the clinic.

Polyethylenimine based magnetic nanoparticles mediated non-viral CRISPR/Cas9 system for genome editing

Clustered regularly interspaced short palindromic repeats-associated protein (CRISPR/Cas9) system has become a revolutionary tool for gene editing. Since viral delivery systems have significant side effects, and naked DNA delivery is not an option, the nontoxic, non-viral delivery of CRISPR/Cas9 components would significantly improve future therapeutic delivery. In this study, we aim at characterizing nanoparticles to deliver plasmid DNA encoding for the CRISPR-Cas system in eukaryotic cells in vitro. CRISPR/Cas9 complexed polyethylenimine (PEI) magnetic nanoparticles (MNPs) were generated. We used a stable HEK293 cell line expressing the traffic light reporter (TLR-3) system to evaluate efficient homology- directed repair (HDR) and non-homologous end joining (NHEJ) events following transfection with NPs. MNPs have been synthesized by co-precipitation with the average particle size around 20 nm in diameter. The dynamic light scattering and zeta potential measurements showed that NPs exhibited narrow size distribution and sufficient colloidal stability. Genome editing events were as efficient as compared to standard lipofectamine transfection. Our approach tested non-viral delivery of CRISPR/Cas9 and DNA template to perform HDR and NHEJ in the same assay. We demonstrated that PEI-MNPs is a promising delivery system for plasmids encoding CRISPR/Cas9 and template DNA and thus can improve safety and utility of gene editing.

Longitudinal study revealing motor, cognitive and behavioral decline in a transgenic minipig model of Huntington's disease

Huntington's disease (HD) is an inherited devastating neurodegenerative disease with no known cure to date. Several therapeutic treatments for HD are in development, but their safety, tolerability and efficacy need to be tested before translation to bedside. The monogenetic nature of this disorder has enabled the generation of transgenic animal models carrying a mutant huntingtin (mHTT) gene causing HD. A large animal model reflecting disease progression in humans would be beneficial for testing the potential therapeutic approaches. Progression of the motor, cognitive and behavioral phenotype was monitored in transgenic Huntington's disease minipigs (TgHD) expressing the N-terminal part of human mHTT. New tests were established to investigate physical activity by telemetry, and to explore the stress-induced behavioral and cognitive changes in minipigs. The longitudinal study revealed significant differences between 6- to 8-year-old TgHD animals and their wild-type (WT) controls in a majority of the tests. The telemetric study showed increased physical activity of 4.6- to 6.5-year-old TgHD boars compared to their WT counterparts during the lunch period as well as in the afternoon. Our phenotypic study indicates progression in adult TgHD minipigs and therefore this model could be suitable for longstanding preclinical studies of HD.

This article has an associated First Person interview with the first author of the paper.

Summary: The transgenic minipig model of Huntington's disease demonstrates a slow-progressing motor, cognitive and behavioral phenotype with later onset in adulthood.

Development of an AAV-Based MicroRNA Gene Therapy to Treat Machado-Joseph Disease

Spinocerebellar ataxia type 3 (SCA3), or Machado-Joseph disease (MJD), is a progressive neurodegenerative disorder caused by a CAG expansion in the ATXN3 gene. The expanded CAG repeat is translated into a prolonged polyglutamine repeat in the ataxin-3 protein and accumulates within inclusions, acquiring toxic properties, which results in degeneration of the cerebellum and brain stem. In the current study, a non-allele-specific ATXN3 silencing approach was investigated using artificial microRNAs engineered to target various regions of the ATXN3 gene (miATXN3). The miATXN3 candidates were screened in vitro based on their silencing efficacy on a luciferase (Luc) reporter co-expressing ATXN3. The three best miATXN3 candidates were further tested for target engagement and potential off-target activity in induced pluripotent stem cells (iPSCs) differentiated into frontal brain-like neurons and in a SCA3 knockin mouse model. Besides a strong reduction of ATXN3 mRNA and protein, small RNA sequencing revealed efficient guide strand processing without passenger strands being produced. We used different methods to predict alteration of off-target genes upon AAV5-miATXN3 treatment and found no evidence for unwanted effects. Furthermore, we demonstrated in a large animal model, the minipig, that intrathecal delivery of AAV5 can transduce the main areas affected in SCA3 patients. These results proved a strong basis to move forward to investigate distribution, efficacy, and safety of AAV5-miATXN3 in large animals.

Age-Related Oxidative Changes in Primary Porcine Fibroblasts Expressing Mutated Huntingtin

BACKGROUND

Huntington's disease (HD) is a devastating neurodegenerative disorder caused by CAG triplet expansions in the huntingtin gene. Oxidative stress is linked to HD pathology, although it is not clear whether this is an effect or a mediator of disease. The transgenic (TgHD) minipig expresses the N-terminal part of human-mutated huntingtin and represents a unique model to investigate therapeutic strategies towards HD. A more detailed characterization of this model is needed to fully utilize its potential.

METHODS

In this study, we focused on the molecular and cellular features of fibroblasts isolated from TgHD minipigs and the wild-type (WT) siblings at different ages, pre-symptomatic at the age of 24-36 months and with the onset of behavioural symptoms at the age of 48 months. We measured oxidative stress, the expression of oxidative stress-related genes, proliferation capacity along with the expression of cyclin B1 and D1 proteins, cellular permeability, and the integrity of the nuclear DNA (nDNA) and mitochondrial DNA in these cells.

RESULTS

TgHD fibroblasts isolated from 48-month-old animals showed increased oxidative stress, which correlated with the overexpression of SOD2 encoding mitochondrial superoxide dismutase 2, and the NEIL3 gene encoding DNA glycosylase involved in replication-associated repair of oxidized DNA. TgHD cells displayed an abnormal proliferation capacity and permeability. We further demonstrated increased nDNA damage in pre-symptomatic TgHD fibroblasts (isolated from animals aged 24-36 months).

CONCLUSIONS

Our results unravel phenotypic alterations in primary fibroblasts isolated from the TgHD minipig model at the age of 48 months. Importantly, nDNA damage appears to precede these phenotypic alterations. Our results highlight the impact of fibroblasts from TgHD minipigs in studying the molecular mechanisms of HD pathophysiology that gradually occur with age.

Adipogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells in Pig Transgenic Model Expressing Human Mutant Huntingtin

BACKGROUND

Although the highest expression of mutant huntingtin (mtHtt) was observed in the brain, its negative effects were also apparent in other tissues. Specifically, mtHtt impairs metabolic homeostasis and causes transcriptional dysregulation in adipose tissue. Adipogenic differentiation can be induced by the activation of two transcription factors: CCAAT/enhancer-binding protein alpha (CEBPα) and peroxisome proliferator-activated receptor gamma (PPARγ). These same transcription factors were found to be compromised in some tissues of Huntington's disease (HD) mouse models and in lymphocytes of HD patients.

OBJECTIVE

This study investigated the adipogenic potential of mesenchymal stem cells (MSCs) derived from transgenic Huntington's disease (TgHD) minipigs expressing human mtHtt (1-548aa) containing 124 glutamines. Two differentiation conditions were used, employing PPARγ agonist rosiglitazone or indomethacin.

METHODS

Bone marrow MSCs were isolated from TgHD and WT minipig siblings and compared by their cluster of differentiation using flow cytometry. Their adipogenic potential in vitro was analyzed using quantitative immunofluorescence and western blot analysis of transcription factors and adipogenic markers.

RESULTS

Flow cytometry analysis did not reveal any significant difference between WT and TgHD MSCs. Nevertheless, following differentiation into adipocytes, the expression of CEBPα nuclear, PPARγ and adipogenic marker FABP4/AP2 were significantly lower in TgHD cells compared to WT cells. In addition, we proved both rosiglitazone and indomethacin to be efficient for adipogenic differentiation of porcine MSCs, with rosiglitazone showing a better adipogenic profile.

CONCLUSIONS

We demonstrated a negative influence of mtHtt on adipogenic differentiation of porcine MSCs in vitro associated with compromised expression of adipogenic transcription factors.

Prevention of esophageal strictures after circumferential endoscopic submucosal dissection

Endoscopic submucosal dissection or widespread endoscopic resection allow the radical removal of circumferential or near-circumferential neoplastic esophageal lesions. The advantage of these endoscopic methods is mini-invasivity and low risk of major adverse events compared to traditional esophagectomy. The major drawback of these extensive resections is the development of stricture - the risk is 70-80% if more than 75% of the circumference is removed and almost 100% if the whole circumference is removed. Thus, an effective method to prevent post-ER/ESD esophageal stricture would be of major benefit, because treatment of strictures requires multiple sessions of endoscopic dilatation and may carry a risk of perforation. Moreover, not all strictures are easy to treat and some patients may develop refractory strictures. There are several techniques and methods, which have been tested in both experimental and/or clinical studies but no one has received general acceptance based on results of high-quality evidence. The studies are usually small with a limited number of patients, there is a lack of randomized controlled trials and some techniques have been described only in experimental studies. Thus, prevention of post-ESD strictures remains an unresolved issue. On the other hand, because of the high risk of stricture and partially proven effectiveness of some preventive techniques, a preventive strategy should be considered in patients undergoing extensive ER/ESD in the esophagus. There is, however, no evidence about the superiority or inferiority of a particular preventive strategy compared to other techniques, moreover, there is paucity of data assessing the effectiveness of the combination of different preventive methods. The best preventive strategies known so far include 1) oral or local administration of corticosteroids; and 2) preventive stenting. Other strategies (preventive sessions of endoscopic dilatation or tissue engineering methods) have unproven efficacy or are too demanding for practical use. Nevertheless, the use of (any) preventive strategy after extensive ER/ESD of the esophagus probably reduces the risk of stricture and the number of endoscopic dilatations, therefore, it should be considered in these patients. However, there is a need for high quality evidence as well as for new ideas and approaches to resolve this important clinical problem.

Mitochondrial Metabolism in a Large-Animal Model of Huntington Disease: The Hunt for Biomarkers in the Spermatozoa of Presymptomatic Minipigs

BACKGROUND

Huntington disease (HD) is a fatal neurodegenerative disorder involving reduced muscle coordination, mental and behavioral changes, and testicular degeneration. In order to further clarify the decreased fertility and penetration ability of the spermatozoa of transgenic HD minipig boars (TgHD), we applied a set of mitochondrial metabolism (MM) parameter measurements to this promising biological material, which can be collected noninvasively in longitudinal studies.

OBJECTIVE

We aimed to optimize methods for MM measurements in spermatozoa and to establish possible biomarkers of HD in TgHD spermatozoa expressing the N-terminal part of mutated human huntingtin.

METHODS

Semen samples from 12 TgHD and wild-type animals, aged 12-65 months, were obtained repeatedly during the study. Respiration was measured by polarography, MM was assessed by the detection of oxidation of radiolabeled substrates (mitochondrial energy-generating system; MEGS), and the content of the oxidative phosphorylation system subunits was detected by Western blot. Three possibly interfering factors were statistically analyzed: the effect of HD, generation and aging.

RESULTS

We found 5 MM parameters which were significantly diminished in TgHD spermatozoa and propose 3 specific MEGS incubations and complex I-dependent respiration as potential biomarkers of HD in TgHD spermatozoa.

CONCLUSIONS

Our results suggest a link between the gain of toxic function of mutated huntingtin in TgHD spermatozoa and the observed MM and/or glycolytic impairment. We determined 4 biomarkers useful for HD phenotyping and experimental therapy monitoring studies in TgHD minipigs.

Mutated Huntingtin Causes Testicular Pathology in Transgenic Minipig Boars

BACKGROUND

Huntington's disease is induced by CAG expansion in a single gene coding the huntingtin protein. The mutated huntingtin (mtHtt) primarily causes degeneration of neurons in the brain, but it also affects peripheral tissues, including testes.

OBJECTIVE

We studied sperm and testes of transgenic boars expressing the N-terminal region of human mtHtt.

METHODS

In this study, measures of reproductive parameters and electron microscopy (EM) images of spermatozoa and testes of transgenic (TgHD) and wild-type (WT) boars of F1 (24-48 months old) and F2 (12-36 months old) generations were compared. In addition, immunofluorescence, immunohistochemistry, Western blot, hormonal analysis and whole-genome sequencing were done in order to elucidate the effects of mtHtt.

RESULTS

Evidence for fertility failure of both TgHD generations was observed at the age of 13 months. Reproductive parameters declined and progressively worsened with age. EM revealed numerous pathological features in sperm tails and in testicular epithelium from 24- and 36-month-old TgHD boars. Moreover, immunohistochemistry confirmed significantly lower proliferation activity of spermatogonia in transgenic testes. mtHtt was highly expressed in spermatozoa and testes of TgHD boars and localized in all cells of seminiferous tubules. Levels of fertility-related hormones did not differ in TgHD and WT siblings. Genome analysis confirmed that insertion of the lentiviral construct did not interrupt any coding sequence in the pig genome.

CONCLUSIONS

The sperm and testicular degeneration of TgHD boars is caused by gain-of-function of the highly expressed mtHtt.

A transgenic minipig model of Huntington's Disease

BACKGROUND

Some promising treatments for Huntington's disease (HD) may require pre-clinical testing in large animals. Minipig is a suitable species because of its large gyrencephalic brain and long lifespan.

OBJECTIVE

To generate HD transgenic (TgHD) minipigs encoding huntingtin (HTT)1-548 under the control of human HTT promoter.

METHODS

Transgenesis was achieved by lentiviral infection of porcine embryos. PCR assessment of gene transfer, observations of behavior, and postmortem biochemical and immunohistochemical studies were conducted.

RESULTS

One copy of the human HTT transgene encoding 124 glutamines integrated into chromosome 1 q24-q25 and successful germ line transmission occurred through successive generations (F0, F1, F2 and F3 generations). No developmental or gross motor deficits were noted up to 40 months of age. Mutant HTT mRNA and protein fragment were detected in brain and peripheral tissues. No aggregate formation in brain up to 16 months was seen by AGERA and filter retardation or by immunostaining. DARPP32 labeling in WT and TgHD minipig neostriatum was patchy. Analysis of 16 month old sibling pairs showed reduced intensity of DARPP32 immunoreactivity in neostriatal TgHD neurons compared to those of WT. Compared to WT, TgHD boars by one year had reduced fertility and fewer spermatozoa per ejaculate. In vitro analysis revealed a significant decline in the number of WT minipig oocytes penetrated by TgHD spermatozoa.

CONCLUSIONS

The findings demonstrate successful establishment of a transgenic model of HD in minipig that should be valuable for testing long term safety of HD therapeutics. The emergence of HD-like phenotypes in the TgHD minipigs will require more study.

Trennung und Charakterisierung cytoplasmatischer Partikel aus normaler und atmungsdefekter Bäckerhefe

Um die Frage nach dem Vorliegen von Mitochondrien in der atmungsdefekten, cytoplasmatischen „petite“-Mutante von Saccharomyces cerevisiae zu klären, wurden aus schonend hergestellten Homogenaten normaler Bäckerhefe und der „petite“-Mutante die in der Zentrifuge zwischen 1500 und 26 300 g sedimentierenden cytoplasmatischen Partikel isoliert und im Saccharose-Dichtegradienten fraktioniert. Die erhaltenen Rohsedimente sowie die einzelnen Fraktionen wurden enzymatisch und elektronenmikroskopisch untersucht. Dichtegradienten-Gleichgewichtszentrifugierung des Sedimentes aus normaler Hefe ergab bei schonendem Homogenisieren zwei Banden, deren spezifisch leichtere (Dichte 1,19 g · cm -3) die Mitochondrien des Rohsedimentes in gereinigter Form enthielt. Die spezifisch schwerere Bande (Dichte 1,23 g · cm-3) bestand aus offenen oder geschlossenen Doppelmembranen, die eine sehr aktive, Mg2⊕ -stimulierte ATPase enthielten, jedoch frei von typisch mitochondralen und mikrosomalen Enzymen waren; diese Membranen sind vermutlich Trümmer des endoplasmatischen Retikulums der Hefezelle. Nach länger dauernder Homogenisierung der Zellen konnte noch eine dritte, meist sehr schwache, Bande beobachtet werden (Dichte 1,14 g · cm-3), die wahrscheinlich aus Mitochondrienfragmenten besteht. Die Auftrennung des Sedimentes der „petite“-Mutante ergab ein prinzipiell gleiches Bild. Auch bei der Mutante zeigten die Atmungsenzyme Succinatdehydrogenase und DPNH-Cytochrom-c-Reduktase eine charakteristische mitochondrale Verteilung im Gradienten (Dichte 1,19 g · cm-3); sie sind also an Mitochondrien gebunden. Von den getesteten Enzymen fehlte lediglich Cytochromoxydase. Die Menge der Mitochondrienfragmente sowie der spezifisch schwereren Membranfraktion (Dichte 1,19 g · cm -3) war meist stark vermehrt.

Der Nachweis von Mitochondrien auch in der „petite“-Mutante ist mit jenen bisherigen Vorstellungen über diese erbliche Veränderung unvereinbar, die die Abwesenheit von Mitochondrien in der Mutante voraussetzen. Die bei der „petite“-Mutation ausfallenden extrachromosomalen Faktoren mit genetischer Kontinuität können also nicht mit den Mitochondrien identisch sein.

Menstrual bleeding patterns and prevalence of bleeding disorders in a multidisciplinary adolescent haematology clinic

Heavy menstrual bleeding (HMB) is a frequent complaint in adolescence. Although HMB is often caused by immaturity of the hypothalamic-pituitary-ovarian axis, bleeding disorders are another common yet often unidentified cause. The aim of this study was to examine the bleeding patterns and prevalence of inherited bleeding disorders among females referred for HMB to a multidisciplinary adolescent haematology clinic. We retrospectively reviewed the first 105 patients (ages 8-18 years) referred to this specialty clinic from February 2009 to December 2011. Using menstrual bleeding questionnaires and medical records, data were extracted regarding demographics, bleeding patterns, frequency and types of bleeding disorders identified, and prescribed interventions. Sixty-two per cent of patients were diagnosed with a bleeding disorder, including platelet storage pool deficiency (36%), von Willebrand's disease (9%), other platelet function defect (8%), Ehlers-Danlos syndrome (7%) and combined bleeding disorders (2%). Comparison of the bleeding profiles for females with and without a bleeding disorder revealed only three factors that were significantly different, including the reported regularity of patients' periods (P = 0.02), description of period flow (P = 0.04) and number of days of each period that the bleeding was described as 'heavy' (P = 0.007). Bleeding disorders are prevalent in adolescent females presenting to a specialty clinic. Specifically, a relatively high proportion of adolescents were diagnosed with platelet storage pool deficiency. In our small population, menstrual bleeding profiles, as examined by a standardized questionnaire, could not identify females with an underlying bleeding disorder, demonstrating the important role of haemostasis testing in the evaluation of adolescents with HMB.

Application of ultrasound in electrochemistry. An overview of mechanisms and design of experimental arrangement

An overview of possible mechanisms by which sonication can influence electrochemical processes is given. Four mechanisms are discussed: – acoustic streaming; – microstreaming and turbulence due to cavitation; – formation of microjets in the course of collapse of cavitation bubble; – shock waves; and possible effects are illustrated on several examples. The most effective process is formation of microjets,which can not only decrease diffusion layer thickness under 1 lm, but also activate (depassivate) electrode surface. Design of experimental arrangement with maximum participation of microjets is proposed. Two approaches are proposed: – focusing of ultrasound on the working electrode and reduction of energy losses by over-pressure; – ‘‘tuning” the reactor to obtain resonance, i.e. formation of stationary waves by activating reactor in itsresonant mode.

Characterization of HIFU transducers designed for sonochemistry application: cavitation distribution and quantification

Acoustic field distribution was determined in HIFU sonoreactors as well as localization of cavitation activity by crossing different techniques: modeling, hydrophone measurements, laser tomography and SCL measurements. Particular care was taken with quantification of this last technique by pixels or photon counting. Cavitation bubbles generated by HIFU are mainly located on the outer layer of the propagation cone in the post-focal zone. Greatest acoustic activity is not located at the geometrical focal, but corresponds to a high concentration of bubbles zone. On the contrary, the main sonochemical activity shifts slightly toward the transducer, whereas quenching of inertial cavitation is observed directly at the focal. Finally, SCL thresholds have been determined.

FEM simulation of a sono-reactor accounting for vibrations of the boundaries

The chemical effects of acoustic cavitation are obtained in sono-reactors built-up from a vessel and an ultrasonic source. In this paper, simulations of an existing sono-reactor are carried out, using a linear acoustics model, accounting for the vibrations of the solid walls. The available frequency range of the generator (19-21 kHz) is systematically scanned. Global quantities are plotted as a function of frequency in order to obtain response curves, exhibiting several resonance peaks. In absence of the precise knowledge of the bubbles size distribution and spatial location, the attenuation coefficient of the wave is taken as a variable, but spatially uniform parameter, and its influence is studied. The concepts of acoustic energy, intensity, active power, and source impedance are recalled, along with the general balance equation for acoustic energy, which is used as a convergence check of the simulations. It is shown that the interface between the liquid and the solid walls cannot be correctly represented by the simple approximations of either infinitely soft, or infinitely hard boundaries. Moreover, the liquid-solid coupling allows the cooling jacket to receive a noticeable part of the input power, although it is not in direct contact with the sonotrode. It may therefore undergo cavitation and this feature opens the perspective to design sono-reactors which avoid direct contact between the working liquid and the sonotrode. Besides, the possibility to shift the main pressure antinode far from the sonotrode area by exciting a resonance of the system is examined.

Allogeneic and autogenous transplantations of MSCs in treatment of the physeal bone bridge in rabbits

Background

The aim of this experimental study on New Zealand's white rabbits was to find differences in the results of treating the distal physeal femoral defect by the transplantation of autologous or allogeneic mesenchymal stem cells (MSCs). After the excision of a created bone bridge in the distal physis of the right femur, modified composite scaffold with MSCs was transplanted into the defect. In animal Group A (n = 11) autogenous MSCs were implanted; in animal Group B (n = 15) allogeneic MSCs were implanted. An iatrogenic physeal defect of the left femur of each animal not treated by MSCs transplantation served as control. The rabbits were euthanized four months after the transplantation. The treatment results were evaluated morphometrically (femoral length and valgus deformity measurement) and histologically (character and quality of the new cartilage).

Results

Four months after the transplantation, the right femurs of the animals in Group A were on average longer by 0.50 ± 0.04 cm (p = 0.018) than their left femurs, the right femurs of rabbits in Group B were on average longer by 0.43 ± 0.01 cm (p = 0.028) than their left femurs.

4 months after the therapeutic transplantation of MSCs valgus deformity of the distal part of the right femur of animals in Group A was significantly lower (by 4.45 ± 1.86°) than that of their left femur (p = 0.028), in Group B as well (by 3.66 ± 0.95° than that of their left femur p = 0.001). However, no significant difference was found between rabbits with transplanted autogenous MSCs (Group A) and rabbits with transplanted allogeneic MSCs (Group B) either in the femur length (p = 0.495), or in its valgus deformity (p = 0.1597). After the MSCs transplantation the presence of a newly formed hyaline cartilage was demonstrated histologically in all the animals (both groups). The ability of transplanted MSCs to survive in the damaged physis was demonstrated in vivo by magnetic resonance, in vitro by Perls reaction and immunofluorescence.

Conclusion

The transplantation of both autogenous and allogeneic MSCs into a defect of the growth plate appears as an effective method of surgical treatment of physeal cartilage injury. However, the Findings point to the conclusion that there is no clear difference in the final effect of the transplantation procedure used.

Energetic balance in an ultrasonic reactor using focused or flat high frequency transducers

In order to undertake irradiation of polymer blocks or films by ultrasound, this paper deals with the measurements of ultrasonic power and its distribution within the cell by several methods. The electric power measured at the transducer input is compared to the ultrasonic power input to the cell evaluated by calorimetry and radiation force measurement for different generator settings. Results obtained in the specific case of new transducer types (composites and focused composites i.e., HIFU: high intensity focused ultrasound) provide an opportunity to conduct a discussion about measurement methods. It has thus been confirmed that these measurement techniques can be applied to HIFU transducers. For all cases, results underlined the fact that measurement of radiation pressure for power evaluation is more adapted to low powers (<15 W) and that measurement by calorimetry is a valid technique for global energy measurements. Composites and monocomponent transducers were compared and it appears that the presence of an adaptation glass plate reduces the efficiency of the monocomponent transducers. The distribution of ultrasonic intensity is qualitatively depicted by sono-chemiluminescence of luminol. Finally, the quantity of energy absorbed by samples placed in the sound field is determined and the temperature distribution monitored as a function of wall distance. This energetic balance allows us to understand the global behaviour of all experimental set-ups made up of a generator-transducer-liquid and sample.

Phenotypic characterization of porcine interfollicular keratinocytes separated by elutriation: a technical note

Separation of epidermal stem cells from other populations in suspensions of epidermal cells by sorting is hampered by a present lack of specific surface markers of this cell type. To address this issue we applied CCE combined with immunocytochemical phenotyping. On the basis of expression profiles for keratins (10, 14, and 19), nucleostemin, galectin-1 and epitopes reactive for this adhesion/growth-regulatory tissue lectin we identified a fraction of very small cells originating from the basal layer. The results demonstrated that CCE has potential merit for separation of epidermal cells to yield a population likely enriched in stem cells.

293 TWO-STEP MATURATION OF BOVINE OOCYTES WITHOUT CDK INHIBITORS: AN ALTERNATIVE TO AFFECT THEIR SUBSEQUENT DEVELOPMENTAL COMPETENCE

The acquisition of meiotic and developmental competence seems to correlate not only with the size of follicles and oocytes but also with the morphology and transcriptional activity of the oocyte nuclei and nucleoli. To secure or increase the fertilization and the developmental competence of bovine oocytes, we have developed a two-step culture system using the specific cyclin dependent kinase inhibitors (Butyrolactone I, Bohemine). However, these drugs have several side effects during the prolonged time of culture. To avoid this disadvantage, we have used in the present experiments modified culture conditions simulating the intrafollicular block of meiosis. In the first step of culture, bovine oocytes isolated from small, medium, and large follicles (2–3, 3–4, and 4–6 mm in diameter, respectively) were kept under conditions that secured for at least 48 h the intact germinal vesicle stage (GV) in more than 90% of oocytes. The second step represented the subsequent 20–22 h in conditions stimulating resumption of meiosis. The effectiveness of this model depended mainly on medium composition: reduced NaHCO3, substitution of serum with serum albumin, addition of antioxidants (curcumin), increased viscosity of a medium by agar (0.3%), and reduction of oxygen concentration (within 6–9%). The reduction of the proportion between the number of cumulus-oocyte complexes (COC) and the amount of medium (within 6–7 mL per COC) should amplify the GVBD-inhibiting effect of oocyte-surrounding granulosa cells. The COC were situated in clots of 6–7 COC per clot. The effectiveness and reversibility of GVBD inhibition depends also on the duration of COC isolation. The full reversibility of GVBD inhibition was controlled morphologically and also by measuring histone H1 and MAP kinase activities. The two-step versus one-step (24 h) maturation technique was evaluated by the percentage of total and hatched Day 9 blastocysts. When compared with one-step maturation, the two-step culture showed a slightly increased proportion of total and hatched blastocysts developed from the smallest follicular category (13.9 vs. 7.1% and 9.2 vs. 3.3% for total and hatched blastocysts, respectively). No significant difference was noticed between between one- and two-step culture when oocytes from large healthy follicles were used. However, the two-step maturation of oocytes from regressing follicles substantially reduced the blastocyst yield (9.7 vs. 39.1% and 4.9 vs. 26.7% for total and hatched blastocysts, respectively). This study was supported by grant of GA CR No. 524/02/0674.

174 ISOLATION, CULTURE AND POTENTIAL USE OF THE PORCINE NEURAL AND EPIDERMAL STEM CELLS

The mammalian brain and epidermis contain stem cells, so-called neural stem cells (NSC) and epidermal stem cells (EpSC). To achieve the full therapeutic potential of stem cells, appropriate animal models have to be used to establish the sequence of pathological changes and to test potential therapies to block these changes. In the following studies miniature pigs were used as a biomedical model. We isolated multipotent cells from brains of porcine fetuses for future use in allotransplantation experiments in the inbred miniature pig strain. Brain tissue from 40- and 80-day-old porcine fetuses was mechanically dissociated, and cells were cultured in serum-free F12/DMEM medium with B27 and N2 supplements, EGF and bFGF. In 3–5 days some cells divided and formed floating spheres that were dissociated to single cell suspension and formed secondary spheres in culture. At all time points tested, the spheres represented mixtures of undifferentiated cells stained with nestin and Ki-67 antibodies and already differentiated neurons (Tu-20, MAP2) and glia (GFAP). After being plated on laminin/fibronectin coated coverslips and cultured in medium containing 2% FBS or 1 μM retinoic acid, the spheres adhered to the surface, and flattened, and cells started to migrate out. After immunofluorescence staining with antibodies to neuronal markers Tu-20 and MAP2, glial marker GFAP and oligodendrocyte marker CNPase showed that all the three cell types were present among differentiated cells. The EpSC are characterized by a slow and unlimited proliferation rate and, therefore, they retain labelled precursors of DNA more extensively than other keratinocytes. The main pool of EpSC is located in the bulge region of the hair follicle root sheath. A new procedure to isolate porcine hair follicles including their root sheaths was developed. The keratinocytes that migrated from hair follicles in the presence of feeder cells were poorly differentiated and specifically expressed galectin-1 or galectin-1-binding sites in their nuclei in co-localization with ΔNp63α. The exclusion of feeder cells from experimental system induced formation of spheroid bodies from these keratinocytes. Approximately one-third of these spheroids were able to adhere to a surface precolonized with feeder cells and to start forming normally growing colonies. Porcine hair follicles represent an excellent model for study of the functional phenotype of hair follicle-originated keratinocytes, and the endogenous lectin Gal-1 seems to be a potential marker of the porcine stem cell compartment of the hair follicle under in vitro conditions.

Timing of Plk1 and MPF activation during porcine oocyte maturation

A Polo-like kinase 1 (Plk1) appears involved in an autocatalytic loop between CDC25C phosphatase and M phase promoting factor (MPF) in Xenopus oocytes and leads to activation of MPF that is required for germinal vesicle breakdown (GVBD). Although similar evidence for such a role of Plk1 in MPF activation during maturation of mammalian oocytes is absent, changes in Plk1 enzyme activity correlate with MPF activation, Plk1 co-localizes with MPF, and microinjection of antibodies neutralizing Plk1 delays GVBD. In this study, we exploited the prolonged time required for maturation of porcine oocytes to define precisely the timing of Plk1 and MPF activation during maturation. GVBD typically occurs between 24 and 26 hr of culture in vitro and meiotic maturation is completed after 40-44-hr culture. We find that Plk1 is activated before MPF, which is consistent with its role in activating MPF in mammalian oocytes.

Cell cycle dependent expression of Plk1 in synchronized porcine fetal fibroblasts

Enzymes of the Polo-like kinase (Plk) family are active in the pathways controlling mitosis in several species. We have cloned cDNA fragments of the porcine homologues of Plk1, Plk2, and Plk3 employing fetal fibroblasts as source. All three partial cDNAs showed high sequence homology with their mouse and human counterparts and contained the Polo box, a domain characteristic for all Polo kinases. The expression levels of Plk1 mRNA at various points of the cell cycle in synchronized porcine fetal fibroblasts were analyzed by both RT-PCR and the ribonuclease protection assay. Plk1 mRNA was barely detectable in G0 and G1, increased during S phase and peaked after the G2/M transition. A monoclonal antibody was generated against an in vitro expressed porcine Plk1-protein fragment and used to detect changes in Plk1 expression at the protein level. Plk1 protein was first detected by immunoblotting at the beginning of S phase and was highest after the G2/M transition. In summary, the Plk1 expression pattern in the pig is similar to that reported for other species. The absence of Plk1 mRNA and protein appears to be a good marker for G0/G1 and thus for the selection of donor cells for nuclear transfer based somatic cloning.

Accumulation of the proteolytic marker peptide ubiquitin in the trophoblast of mammalian blastocysts

Ubiquitination is a universal protein degradation pathway in which the molecules of 8.5-kDa proteolytic peptide ubiquitin are covalently attached to the epsilon-amino group of the substrate's lysine residues. Little is known about the importance of this highly conserved mechanism for protein recycling in mammalian gametogenesis and fertilization. The data obtained by the students and faculty of the international training course Window to the Zygote 2000 demonstrate the accumulation of ubiquitin-cross-reactive structures in the trophoblast, but not in the inner cell mass of the expanding bovine and mouse blastocysts. This observation suggests that a major burst of ubiquitin-dependent proteolysis occurs in the trophoblast of mammalian peri-implantation embryos. This event may be important for the success of blastocyst hatching, differentiation of embryonic stem cells into soma and germ line, and/or implantation in both naturally conceived and reconstructed mammalian embryos.

Determination of bacterial cell dry mass by transmission electron microscopy and densitometric image analysis

We applied transmission electron microscopy and densitometric image analysis to measure the cell volume (V) and dry weight (DW) of single bacterial cells. The system was applied to measure the DW of Escherichia coli DSM 613 at different growth phases and of natural bacterial assemblages of two lakes, Piburger See and Gossenköllesee. We found a functional allometric relationship between DW (in femtograms) and V (in cubic micrometers) of bacteria (DW = 435.V0.86); i.e., smaller bacteria had a higher ratio of DW to V than larger cells. The measured DW of E. coli cells ranged from 83 to 1,172 fg, and V ranged from 0.1 to 3.5 micron 3 (n = 678). Bacterial cells from Piburger See and Gossenköllesee (n = 465) had DWs from 3 fg (V = 0.003 micron 3) to 1,177 fg (V = 3.5 microns3). Between 40 and 50% of the cells had a DW of less than 20 fg. By assuming that carbon comprises 50% of the DW, the ratio of carbon content to V of individual cells varied from 466 fg of C micron-3 for Vs of 0.001 to 0.01 micron3 to 397 fg of C micron3 (0.01 to 0.1 micron3) and 288 fg of C micron3 (0.1 to 1 micron 3). Exponentially growing and stationary cells of E. coli DSM 613 showed conversion factors of 254 fg of C micron-3 (0.1 to 1 micron3) and 211 fg of C micron-3 (1 to 4 micron3), respectively. Our data suggest that bacterial biomass in aquatic environments is higher and more variable than previously assumed from volume-based measurements.

Preparation and characterization of poly-(D,L-lactide-co-glycolide) and poly-(L-lactic acid) microspheres with entrapped pneumotropic bacterial antigens

Poly-(lactide-co-glycolide) microspheres with entrapped antigen have shown considerable promise as controlled release vaccines. To enhance the immunomodulatory effect of LW 50020, a bacterial lysate of seven common respiratory pathogens used perorally as an immunomodulator, we prepared poly-(D,L-lactide-co-glycolide) (PLG) and poly-(L-lactic acid) (PLA) microspheres with entrapped immunomodulator by solvent evaporation or solvent extraction double emulsion techniques. Physical properties, such as particle size, LW 50020 entrapment rate, antigen release patterns and morphological characteristics were investigated. All preparations displayed a high degree of antigen loading up to 95%, whereas size, surface morphology and antigen release patterns were significantly influenced by the method of preparation and the polymer components used. Solvent evaporation microspheres are porous particles from 0.8 micron to 2.0 microns in diameter, that show a rapid antigen release for PLG, and a moderate antigen release for PLA microspheres within 33 days. Solvent extraction microspheres have proven to be particles from 1.1 microns to 5.0 microns in diameter showing a smooth surface and a medium antigen release rate over 33 days. SDS-PAGE and immunoblotting of extracted antigen confirmed that the molecular weight and antigenicity of the immunomodulator remained unaltered by the entrapment procedure.

Ultrastructural analysis of thymic nurse cell epithelium

Thymic nurse cells (TNC), a paradigmatic cell type of cortical epithelium, are large lymphoid-epithelial cell complexes of thymocytes enclosed within vacuoles lined by the epithelial cell membrane. TNC express major histocompatibility complex (MHC) class I and class II molecules on their surface and vacuole-lining membranes at high density and it was suggested that TNC provide an optimal microenvironment for positive selection of T cells. In this report we present electron microscopical data demonstrating that chicken TNC display morphological structures of exocytosis previously shown for hormone-secreting cells. In TNC, however, exocytosis is restricted to the capillary cleft between the epithelial cell and engulfed thymocytes. Thus, besides physical contact between the epithelial cell and enclosed thymocytes, TNC may additionally influence the development of thymocytes through release of soluble factors in a restricted microenvironment. By employing the 3-(2,4-dinitroanilino)-3'-amino-N-methyl-propylamine technique which at the ultrastructural level detects acidic organelles involved in processing of antigens presented by MHC class II molecules, we also show that TNC contain acidic compartments similar to classical antigen-presenting cells, i.e. early and late endosomes and lysosomes, albeit in a lower amount than in thymic dendritic cells. This fact provides evidence that TNC not only are capable of antigen presentation but also possess the intracellular machinery for antigen processing.

[Enteral anastomosis with the biofragmentable Valtrac ring. A prospective study]

In a prospective study, 150 enteral anastomoses using the new Valtrac biofragmentable anastomosis ring (BAR) are described. The manipulation involved was simple to learn and standardised intestinal anastomoses could be created at various bowel segments. No stenoses or postoperative bleeding occurred, the suture dehiscence rate was low. The use of these rings can be recommended to achieve a high level of standardisation for colon anastomoses and small bowel-colon anastomoses without restriction, whereas for other localisations the number of cases is too small to allow a final assessment to be made.

Determination of fatty acids as phenacyl esters in rat adipose tissue and blood vessel walls by high-performance liquid chromatography

Twenty-two biologically relevant (6:0-22:6) saturated, monounsaturated and polyunsaturated fatty acids were separated by reversed-phase high-performance liquid chromatography after derivatization with phenacyl bromide. An optimal resolution of the critical combinations linolenic-myristic, docosahexaenoic-palmitoleic-arachidonic and palmitic-oleic acids and cis and trans isomers of octadecenoic (n9) and octadecadienoic (n9, 12) acids was achieved by continuous gradient elution with methanol-acetonitrile-water. Elution of mixtures of 6:0-22:1 fatty acids was completed within 80 min at a flow-rate of 1 ml/min. By the use of UV detection at 242 nm the detection limits for short- and long-chain fatty acids were found to be about 0.8 and 12 ng per injection, respectively. Linearity was tested up to 100 ng. The method was applied to the determination of fatty acids in rat adipose tissue and blood vessel walls of animals fed hydrogenated fat diets. The results are comparable to those obtained by gas chromatography and surpass the latter for the resolution of oleic and elaidic acids.