Comprehensive Analysis of Leukocytes, Vascularization and Matrix Metalloproteinases in Human Menstrual Xenograft Model

In our previous study, menstrual-like changes in mouse were provoked through the pharmacologic withdrawal of progesterone with mifepristone following induction of decidualization. However, mouse is not a natural menstruation animal, and the menstruation model using external stimuli may not truly reflect the occurrence and development of the human menstrual process. Therefore, we established a model of menstruation based on human endometrial xenotransplantation. In this model, human endometrial tissues were transplanted subcutaneously into SCID mice that were ovarectomized and supplemented with estrogen and progestogen by silastic implants with a scheme imitating the endocrinological milieu of human menstrual cycle. Morphology, hormone levels, and expression of vimentin and cytokeratin markers were evaluated to confirm the menstrual-like changes in this model. With 28 days of hormone treatment, transplanted human endometrium survived and underwent proliferation, differentiation and disintegration, similar to human endometrium in vivo. Human CD45+ cells showed a peak of increase 28 days post-transplantation. Three days after progesterone withdrawal, mouse CD45+ cells increased rapidly in number and were significantly greater than human CD45+ cell counts. Mouse CD31+ blood vascular-like structures were detected in both transplanted and host tissues. After progesterone withdrawal, the expression levels of matrix metalloproteinases (MMP) 1, 2, and 9 were increased. In summary, we successfully established a human endometrial xenotransplantation model in SCID mice, based on the results of menstrual-like changes in which MMP-1, 2 and 9 are involved. We showed that leukocytes are originated from in situ proliferation in human xenografts and involved in the occurrence of menstruation. This model will help to further understand the occurrence, growth, and differentiation of the endometrium and the underlying mechanisms of menstruation

Temporal context and conditional associative learning

<p>Abstract</p> <p>Background</p> <p>We investigated how temporal context affects the learning of arbitrary visuo-motor associations. Human observers viewed highly distinguishable, fractal objects and learned to choose for each object the one motor response (of four) that was rewarded. Some objects were consistently preceded by specific other objects, while other objects lacked this task-irrelevant but predictive context.</p> <p>Results</p> <p>The results of five experiments showed that predictive context consistently and significantly accelerated associative learning. A simple model of reinforcement learning, in which three successive objects informed response selection, reproduced our behavioral results.</p> <p>Conclusions</p> <p>Our results imply that not just the representation of a current event, but also the representations of past events, are reinforced during conditional associative learning. In addition, these findings are broadly consistent with the prediction of attractor network models of associative learning and their prophecy of a persistent representation of past objects.</p

Endometrial apoptosis and neutrophil infiltration during menstruation exhibits spatial and temporal dynamics that are recapitulated in a mouse model.

Abstract Menstruation is characterised by synchronous shedding and restoration of tissue integrity. An in vivo model of menstruation is required to investigate mechanisms responsible for regulation of menstrual physiology and to investigate common pathologies such as heavy menstrual bleeding (HMB). We hypothesised that our mouse model of simulated menstruation would recapitulate the spatial and temporal changes in the inflammatory microenvironment of human menses. Three regulatory events were investigated: cell death (apoptosis), neutrophil influx and cytokine/chemokine expression. Well-characterised endometrial tissues from women were compared with uteri from a mouse model (tissue recovered 0, 4, 8, 24 and 48 h after removal of a progesterone-secreting pellet). Immunohistochemistry for cleaved caspase-3 (CC3) revealed significantly increased staining in human endometrium from late secretory and menstrual phases. In mice, CC3 was significantly increased at 8 and 24 h post-progesterone-withdrawal. Elastase+ human neutrophils were maximal during menstruation; Ly6G+ mouse neutrophils were maximal at 24 h. Human endometrial and mouse uterine cytokine/chemokine mRNA concentrations were significantly increased during menstrual phase and 24 h post-progesterone-withdrawal respectively. Data from dated human samples revealed time-dependent changes in endometrial apoptosis preceding neutrophil influx and cytokine/chemokine induction during active menstruation. These dynamic changes were recapitulated in the mouse model of menstruation, validating its use in menstrual research

Hypoxia and hypoxia inducible factor-1α are required for normal endometrial repair during menstruation

About a quarter of pre-menopausal women will suffer from heavy menstrual bleeding in their lives. Here, Maybin and colleagues show hypoxia and subsequent activation of HIF-1α during menses are required for normal endometrial repair, and identify pharmacological stabilisation of HIF-1α as a potential therapeutic strategy for this debilitating condition

Motor Skill Learning, Retention, and Control Deficits in Parkinson's Disease

Parkinson's disease, which affects the basal ganglia, is known to lead to various impairments of motor control. Since the basal ganglia have also been shown to be involved in learning processes, motor learning has frequently been investigated in this group of patients. However, results are still inconsistent, mainly due to skill levels and time scales of testing. To bridge across the time scale problem, the present study examined de novo skill learning over a long series of practice sessions that comprised early and late learning stages as well as retention. 19 non-demented, medicated, mild to moderate patients with Parkinson's disease and 19 healthy age and gender matched participants practiced a novel throwing task over five days in a virtual environment where timing of release was a critical element. Six patients and seven control participants came to an additional long-term retention testing after seven to nine months. Changes in task performance were analyzed by a method that differentiates between three components of motor learning prominent in different stages of learning: Tolerance, Noise and Covariation. In addition, kinematic analysis related the influence of skill levels as affected by the specific motor control deficits in Parkinson patients to the process of learning. As a result, patients showed similar learning in early and late stages compared to the control subjects. Differences occurred in short-term retention tests; patients' performance constantly decreased after breaks arising from poorer release timing. However, patients were able to overcome the initial timing problems within the course of each practice session and could further improve their throwing performance. Thus, results demonstrate the intact ability to learn a novel motor skill in non-demented, medicated patients with Parkinson's disease and indicate confounding effects of motor control deficits on retention performance

fMRI Supports the Sensorimotor Theory of Motor Resonance

The neural mechanisms mediating the activation of the motor system during action observation, also known as motor resonance, are of major interest to the field of motor control. It has been proposed that motor resonance develops in infants through Hebbian plasticity of pathways connecting sensory and motor regions that fire simultaneously during imitation or self movement observation. A fundamental problem when testing this theory in adults is that most experimental paradigms involve actions that have been overpracticed throughout life. Here, we directly tested the sensorimotor theory of motor resonance by creating new visuomotor representations using abstract stimuli (motor symbols) and identifying the neural networks recruited through fMRI. We predicted that the network recruited during action observation and execution would overlap with that recruited during observation of new motor symbols. Our results indicate that a network consisting of premotor and posterior parietal cortex, the supplementary motor area, the inferior frontal gyrus and cerebellum was activated both by new motor symbols and by direct observation of the corresponding action. This tight spatial overlap underscores the importance of sensorimotor learning for motor resonance and further indicates that the physical characteristics of the perceived stimulus are irrelevant to the evoked response in the observer

Automated operant assessments of Huntington's Disease mouse models

Huntington’s disease (HD) presents clinically with a triad of motor, cognitive, and psychiatric symptoms. Cognitive symptoms often occur early within the disease progression, prior to the onset of motor symptoms, and they are significantly burdensome to people who are affected by HD. In order to determine the suitability of mouse models of HD in recapitulating the human condition, these models must be behaviorally tested and characterized. Operant behavioral testing offers an automated and objective method of behaviorally profiling motor, cognitive, and psychiatric dysfunction in HD mice. Furthermore, operant testing can also be employed to determine any behavioral changes observed after any associated interventions or experimental therapeutics. We here present an overview of the most commonly used operant behavioral tests to dissociate motor, cognitive, and psychiatric aspects of mouse models of HD

Regulation of endometrial regeneration; mechanisms contributing to repair and restoration of tissue integrity following menses

The human endometrium is a dynamic, multi-cellular tissue that lines the inside of the uterine cavity. During a woman’s reproductive lifespan the endometrium is subjected to cyclical episodes of proliferation, angiogenesis, differentiation/decidualisation, shedding (menstruation), repair and regeneration in response to fluctuating levels of oestrogen and progesterone secreted by the ovaries. The endometrium displays unparalleled, tightly regulated, tissue remodelling resulting in a healed, scar-free tissue following menses or parturition. Mechanisms responsible for initiation of menses have been well documented: following progesterone withdrawal there is an increase in inflammatory mediators, focal hypoxia and induction and activation of matrix-degrading enzymes. In contrast, the molecular and cellular changes responsible for rapid, regulated, tissue repair at a time when oestrogen and progesterone are low are poorly understood. Histological studies using human menstrual phase endometrium have revealed that tissue destruction and shedding occur in close proximity to re-epithelialisation/repair. It has been proposed that re-epithelialisation involves proliferation of glandular epithelial cells in the remaining basal compartment; there is also evidence for a contribution from the underlying stroma. A role for androgens in the regulation of apoptosis of endometrial stromal cells has been proposed but the impact of androgens on tissue repair has not been investigated. Studies using human xenografts and primates have been used to model some aspects of the impact of progesterone withdrawal but simultaneous shedding (menses) and repair have not been modelled in mice; the species of choice for translational biomedical research. In the course of the studies described in this thesis, the following aims have been addressed: 1. To establish a model of menses in the mouse which mimics menses in women, namely; simultaneous breakdown and repair, overt menstruation, immune cell influx, tissue necrosis and re-epithelialisation. 2. To use this model to determine if the stromal cell compartment contributes to endometrial repair. 3. To examine the impact of androgens on the regulation of menses (shedding) and repair. An informative mouse model of endometrial breakdown that was characterised by overt menses, as well as rapid repair, was developed. Immunohistological evidence for extensive tissue remodelling including active angiogenesis, transient hypoxia, epithelial cell-specific proliferation and re-epithelialisation were obtained by examining uterine tissues recovered during an “early window of breakdown and repair” (4 to 24 hours after progesterone withdrawal). Novel data included identification of stromal cells that expressed epithelial cell markers, close to the luminal surface following endometrial shedding, suggesting a role for mesenchymal to epithelial transition (MET) in re-epithelialisation of the endometrium. In support of this idea, array and qRTPCR analyses revealed dynamic changes in expression of mRNAs encoded by genes known to be involved in MET during the window of breakdown and repair. Roles for hypoxia and tissue-resident macrophages in breakdown and tissue remodelling were identified. Treatment of mice with dihydrotestosterone to mimic concentrations of androgens circulated in women at the time of menses had an impact on the timing and duration of endometrial breakdown. Array analysis revealed altered expression of genes implicated in MET and angiogenesis/inflammation highlighting a potential, previously unrecognised role for androgens in regulation of tissue turnover during menstruation. In summary, using a newly refined mouse model new insights were obtained, implicating androgens and stromal MET in restoration of endometrial tissue homeostasis during menstruation. These findings may inform development of new treatments for disorders associated with aberrant repair such as heavy menstrual bleeding and endometriosis