Jiri Klima

A Transgenic Minipig Model of Huntington's Disease

BACKGROUND Some promising treatments for Huntingtons 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.

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 substrates 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.

Mutated Huntingtin Causes Testicular Pathology in Transgenic Minipig Boars

Background: Huntingtons 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.

The Minipig as an Animal Model in Biomedical Stem Cell Research

Pigs and miniature pigs are steadily gaining importance as large animal models in the field of regenerative medicine, including stem cell research. With their size, organ capacity, and physiology resembling in several aspects that of humans, pigs are well suited for preclinical experiments and long-term safety studies. In this chapter, we summarize our experience with the isolation and culture of several somatic stem cell populations from fetal and adult pig tissue and briefly review their potential usefulness in future stem cell-based therapies. We also provide protocols for the isolation of fetal porcine neural stem cells (NSCs), adult bone marrow mesenchymal stem cells (MSCs), and epidermal progenitor cells (EPCs) from adult hair follicles.

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.

Survival of syngeneic and allogeneic iPSC–derived neural precursors after spinal grafting in minipigs

Syngeneic iPSC–derived neurons survive and mature without immunosuppression after grafting into the spinal cord of adult pigs. Stem cell transplants in pigs with spinal cord injury Neural precursor cells (NPCs) hold promise for treating spinal cord injury (SCI). Testing viability and engraftment properties of NPC transplants in large-animal models is necessary for understanding the clinical potential of this approach. In a new study, Strnadel et al. transplanted syngeneic and allogeneic induced pluripotent stem cell–derived NPCs (iPSC-NPCs) into the spinal cords of naïve pigs and animals with SCI. The transplanted cells showed a good safety profile, long-term survival, and differentiation into mature neurons and glial cells. Successful engraftment of allogeneic iPSC-NPCs required only temporary immunosuppression, an important consideration for the future clinical evaluation of iPSC-NPCs for treating SCI. The use of autologous (or syngeneic) cells derived from induced pluripotent stem cells (iPSCs) holds great promise for future clinical use in a wide range of diseases and injuries. It is expected that cell replacement therapies using autologous cells would forego the need for immunosuppression, otherwise required in allogeneic transplantations. However, recent studies have shown the unexpected immune rejection of undifferentiated autologous mouse iPSCs after transplantation. Whether similar immunogenic properties are maintained in iPSC-derived lineage-committed cells (such as neural precursors) is relatively unknown. We demonstrate that syngeneic porcine iPSC-derived neural precursor cell (NPC) transplantation to the spinal cord in the absence of immunosuppression is associated with long-term survival and neuronal and glial differentiation. No tumor formation was noted. Similar cell engraftment and differentiation were shown in spinally injured transiently immunosuppressed swine leukocyte antigen (SLA)–mismatched allogeneic pigs. These data demonstrate that iPSC-NPCs can be grafted into syngeneic recipients in the absence of immunosuppression and that temporary immunosuppression is sufficient to induce long-term immune tolerance after NPC engraftment into spinally injured allogeneic recipients. Collectively, our results show that iPSC-NPCs represent an alternative source of transplantable NPCs for the treatment of a variety of disorders affecting the spinal cord, including trauma, ischemia, or amyotrophic lateral sclerosis.

C13 Physical activity monitoring of transgenic minipigs using telemetric accelerometer

Background Animal models are very useful tool for research in the field of Huntington’s disease (HD). In the last years large animal models were developed to improve understanding of HD because the complexity of their brain. Transgenic (TgHD) minipig expressing N-terminal part of human huntingtin with 124 CAG/CAA repeats seems to be very promising model of HD. Aims The aim of study was to find and measure the physical activity disturbances by three-years-old boars using telemetric accelerometer. The disturbances could be characterised by deficit in sleep and circadian organisation of TgHD boars expressing human mutated huntingtin in comparison with wild type boars (WT). Methods/techniques The physical activity was continuously measured by five TgHD and five WT animals during the six days. RodentPACK2 transmitter was used as telemetric accelerometer. Every pig wore the collar with one accelerometer. Measured data was statistically processed in the software ecgAUTO provided by accelerometer manufacturer – emka TECHNOLOGIES. Results/outcome The analysis have shown significant decrease of physical activity of TgHD boars between 4:40 and 5:30 a.m. (after night sleep and before morning feeding) in comparison with WT boars which could be explained with disturbed energy metabolism. Conclusions Telemetric accelerometers will play an important role in the study of physical activity because it is precise, objective and automatic method for a classification of physical activity disturbances. It will lead to deeper characterisation of large animal HD models in preclinical and clinical phase. Acknowledgements This work was supported by the 7 F – EEA/Norwegian Financial Mechanism (2008–2017) 7F14308, CHDI Foundation (A-5378, A-8248), ExAM – CZ.1.05./2.1.00/03.0124, RVO: 67985904 and SGS14/191/OHK3/3T/13 – Advanced algorithms of digital signal processing and their applications.

B06 Genotoxic stress in fibroblasts and mesenchymal stem cells isolated from miniature pigs transgenic for n-terminal part of mutated human huntingtin

Background Huntingtons disease (HD) is a dominant inherited disorder caused by mutation in huntingtin (htt) protein that causes massive neural cell death leading to neurodegeneration. Mutated huntingtin (mt htt) induces a cascade of events that stimulates DNA breaks and the activation of DNA damage response pathway. This genotoxic stress is followed by activation of the MDC1 and H2AX proteins, in the early stages of HD pathogenesis. Expression of htt occurs in cells of neuronal and non-neuronal origin. Aims The aim of our research is to study genetoxic stress of mt htt on fibroblasts and mesenchymal stem cells (MSCs) of our miniature pig model for HD. Methods Currently, we have three generations of transgenic (tg) minipigs for N-terminal part of the human mt htt (548 aa, 124 Q). Each litter presents wild type (wt) and tg siblings at an approximate ratio 1:1 with the same genetic background. DNA damage was examined on fibroblasts and MSCs isolated from tg and wt minipigs using confocal microscopy, immunocytochemistry, Western blot analysis and the dynamic of tg and wt cell proliferation was tested by life cell imaging. Results The significant increase of MDC1 and γH2AX proteins, indicating DNA damage, was proved by immunocytochemistry and also Western blot analysis. Proliferation tests could not clearly establish the genotoxic stress of tg fibroblasts and MSCs. Conclusions We will continue in our studies to observe changes in genotoxic stress during the lifespan of our minipigs. HD tg miniature pig represents a perspective large animal model for the research of molecular mechanisms of mt htt.