21 research outputs found
‘Albania: €1’ or the story of ‘big policies, small outcomes’: how Albania constructs and engages its diaspora
Since the fall of the communist regime in the early 1990s, Albania has experienced one of the most significant emigrations in the world as a share of its population. By 2010 almost half of its resident population was estimated to be living abroad – primarily in neighbouring Greece and Italy, but also in the UK and North America. This chapter discusses the emergence and establishment of the Albanian diaspora, its temporal and geographical diversity, and not least its involvement with Albania itself. Albania’s policymaking and key institutions are considered, with a focus on matters of citizenship; voting rights; the debate on migration and development; and not least the complex ways in which kin-state minority policies – related to ethnic Albanians living in Kosovo, Montenegro, southern Serbia, Macedonia and Greece – are interwoven with Albania’s emigration policies
Differentiation potential of cardiac stem and progenitor cells in a model of heterotopic heart transplantation
Cardiac stem cells were identified in mammalian hearts and
they were found to regenerate cardiomyocytes and vessels when
injected into an infarcted heart. We used the model of
heterotopic heart transplantation to investigate spontaneous
potential of cardiac stem and progenitor cells to differentiate
properly after tissue damage and remodeling. In a previous
study, in which hearts from normal rat donors were heterotopically
transplanted into GFP+ transgenic rat hosts, we found
abundant extracardiac GFP+ cells that did not contribute to de novo cardiogenesis, but generated rare hybrid cardiomyocytes
by cell fusion with resident cardiac cells. In the same transplants
we recently identified a robust population of GFP 12 cells
expressing markers of stem and mesenchymal cells. Markers of
cardiac commitment and neural stem cells identified different
populations of cell progenitors. The overall number of these
cells increased 5-fold in heart transplants as compared to normal
hearts. The majority of these cells did not progress towards
maturation, however cardiomyocytes expressing phosphohistone-
H3 were occasionally found. A major issue is whether
cardiac stem cells can detach from a damaged heart, circulate
and from the bloodstream home again into the heart. To address
this question the heart of GFP+ transgenic rats was transplanted
into a normal host, which had been previously treated with
isoproterenol, to induce damage in the native heart. Native
hearts, retrieved 15 days after surgery, did not show any significant
engraftment by cardiac stem cells mobilized from the
heart transplant
Host-derived circulating cells do not significantly contribute to cardiac regeneration in heterotopic rat heart transplants
Host-derived circulating cells generate hybrid cardiomyocytes by cell fusion in heterotopic heart xenotransplantations
Apoptosis in Acute Vascular Rejection of Porcine Organs Trasplanted into Primates in not an Antibody triggered Event
Apoptotic events are consistently observed in acute xenograft rejection (AHXR) of pig organs transplanted into primates. The pathogenic events responsible for these findings have yet to be identified, however. The aim of this study was to investigate the role of the humoral immune response elicited in the onset of apoptosis in the xenograft of long-term surviving primates.
Methods: Four nephrectomised cynomolgus monkeys received an hDAF porcine renal xenograft (Novartis Pharma AG, Basel, Switzerland) and were immunosuppressed with cyclophosphamide (up to 4 doses), cyclosporine A, mycophenolate sodium (Novartis) and steroids. Sera from each primate were sampled pre-transplant and at the time of
euthanasia. The apoptotic capacity of the sera was assessed on porcine aortic endothelial cells (PAEC) isolated from hDAF pigs. Primary cells were incubated for 18, 24 and 48 hrs
with different concentrations of primate sera. Cells were stained with propidium iodide and analysed by flow cytometry for the appearance of a sub-diploid DNA peak. Swine rTNFα (50-100ng/ml), camptothecin (5-10μM) and normal human serum (NHS) were used as positive controls; normal pig serum (NPS) was used as a negative control.
Results: AHRX in the xenograft was consistently observed when the animals were euthanised between 13 and 90 days after transplantation. At the doses considered, TNFα and camptothecin led to apoptosis of 14-32% of the PAEC analysed. At the concentration used, NHS was able to induce apoptosis of up to 28% of PAEC. In contrast, apoptosis was
not observed when PAEC were incubated with the primate sera taken before transplantation or at the time of euthanasia in the presence of AHXR.
Conclusion: The apoptosis invariably observed in AHXR of pig organs transplanted into primates is not an antibody-driven event
Implantation of decellularized pulmonary homograft in Italy (ESPOIR project): preliminary report
Host-derived circulating cells generate hybrid cardiomyocytes by cell fusion in heterotopic heart xenotransplantations
The possibility to regenerate dead myocardium by cell therapy using either extra-cardiac or
cardiac stem cells is the object of an intense investigation. Whereas much work has been done
to assess the potential of injected cells to form new myocardium, little is known about the
spontaneous recruitment of stem cells through the circulation. Host-derived cardiomyocytes
were found in human sex-mismatched heart transplantations, however the relative proportion
of this phenomenon was estimated very high by some authors and negligible by others. In
heterotopic heart allo-transplantation, we previously demonstrated that circulating cells engraft
the heart transplants but do not significantly contribute to cardiac repair. Possible fusion
events, as opposed to transdifferentiation, had been hypothesized but not proved. Here, we
took advantage by the use of xeno-transplantations, in which markers of both donor and
recipient cells are available, to address this issue. Xeno-transplantations were performed using
GFP transgenic rats as hosts, and either Syrian hamsters (n8) or transgenic mice expressing
the lacZ reporter gene under the control of the cardiac troponin I promoter (n6), as heart
donors. All transplants, which were retrieved 15 days after surgery, contained a large quantity
of GFP inflammatory cells. In 7 of 8 hamster-to-rat heart transplants GFP mature
cardiomycytes were found, with percentages ranging from 0.0001% to 0.034%. No more than
15 GFP cardiomyocytes were detected in all mouse-to-rat transplants. We also found rare
small GFP cells expressing markers of cardiac progenitor cells, such as GATA-4 and MEF2C,
in all xenografts. All GFP cardiomyocytes identified in our study co-expressed GFP (the host\u2019s
marker) and either hamster-specific antigens or the LacZ marker of mouse origin (the donor\u2019s
markers). Thus, using both an immunological and a genetic approach, we conclusively
demonstrate that in our experimental model circulating cells do not significantly contribute to
form new myocardium, rather they generate hybrid cardiomyocytes by cell fusion
Customized bioreactor enables the production of 3D diaphragmatic constructs influencing matrix remodeling and fibroblast overgrowth
The production of skeletal muscle constructs useful for replacing large defects in vivo, such as in congenital diaphragmatic hernia (CDH), is still considered a challenge. The standard application of prosthetic material presents major limitations, such as hernia recurrences in a remarkable number of CDH patients. With this work, we developed a tissue engineering approach based on decellularized diaphragmatic muscle and human cells for the in vitro generation of diaphragmatic-like tissues as a proof-of-concept of a new option for the surgical treatment of large diaphragm defects. A customized bioreactor for diaphragmatic muscle was designed to control mechanical stimulation and promote radial stretching during the construct engineering. In vitro tests demonstrated that both ECM remodeling and fibroblast overgrowth were positively influenced by the bioreactor culture. Mechanically stimulated constructs also increased tissue maturation, with the formation of new oriented and aligned muscle fibers. Moreover, after in vivo orthotopic implantation in a surgical CDH mouse model, mechanically stimulated muscles maintained the presence of human cells within myofibers and hernia recurrence did not occur, suggesting the value of this approach for treating diaphragm defects
Histopathological findings in the gastrointestinal tract of primate recipients of porcine renal xenografts following different immunosuppressive regimens.
BACKGROUND: Cyclophosphamide (CYP) and methotrexate (MTX) have been used as immunosuppressants in induction or maintenance protocols in a large variety of xenotransplantation models. Combining the use of transgenic porcine organs expressing human decay-accelerating factor (hDAF) with immunosuppressive therapy that included the use of CYP or MTX, survival of primate recipients of life-supporting renal xenografts has been prolonged. However, both drugs can cause significant systemic toxicity and, in particular, gastrointestinal (GI) toxicity. To date only limited data have been reported on the histopathological features deriving from the use of such agents in non-human primates. METHODS: Cyclophosphamide or MTX was used as part of the immunosuppressive regimen in 15 bilaterally nephrectomized non-human primate (Macaca fascicularis) recipients of a life-supporting hDAF porcine kidney. At post-mortem, a detailed analysis of the GI tract in animals receiving either CYP or MTX was performed. Paraffin-embedded sections of each portion of the GI tract were prepared and stained with hematoxylin and eosin (H&E). In some animals, additional investigations by immunohistochemistry (CD3, CD5, CD20, CD79 alpha cy, lambda, and kappa light chains) and by in situ hybridization for EBV encoded RNA (EBER) were undertaken. RESULTS:
The xenografted animals from the CYP group had a mean survival of 31 days (range: 0 to 90 days); animals from the MTX group survived a median of 14 days (range: 0 to 39 days). GI complications were the most frequent cause of euthanasia after renal failure. In CYP-treated animals GI-tract lesions were primarily characterized by diffuse, severe lymphoplasmocytic mucosal inflammatory infiltrate. Variable degrees of villi atrophy and fusion, gut-associated lymphoid tissue (GALT) and goblet cell hyperplasia were also observed. In MTX-treated primates, findings were consistent with severe villi atrophy associated with mild-to-moderate disseminated lymphoplasmocytic infiltration. CONCLUSIONS: In conclusion, GI tract lesions are an early and consistent finding when CYP or MTX are used as induction agents in this model. The two compounds induce different types of GI tract damage, however, in agreement with their different mechanisms of action. Whilst CYP primarily determines inflammatory lesions, MTX leads to a degenerative type of damage. This study indicates that immunosuppressive drugs can cause severe GI tract damage in primate recipients of renal xenografts and may be responsible for life-threatening lesions
The effects of basic fibroblast growth factor in an animal model of acute mechanically induced right ventricular hypertrophy.
OBJECTIVE:
To evaluate the effect of a continuous infusion of basic fibroblast growth factor on the adaptive potential of the right ventricular myocardium after 30 days of mechanically induced overload in rats.Materials and methodsWe banded the pulmonary trunk, so as to increase the systolic workload of the right ventricle, in six Lewis/HanHsd rats at the age of 11 weeks, using six adult rats as controls. The six adult rats were also banded and received an additional continuous infusion of basic fibroblastic growth factor, using six rats with a continuous infusion of basic fibroblastic growth factor only as controls. We analysed the functional adaptation and structural changes of the right ventricular myocardium, blood vessels, and interstitial tissue 30 days after the increased afterload.
RESULTS:
The pulmonary artery banding induced an increase in the right ventricular free wall thickness of banded rats when compared with controls, which was mainly justified by an increase in cardiomyocyte area and in the percentage of extracellular fibrosis. The infusion of basic fibroblastic growth factor promotes a more extensive capillary network in banded rats (p < 0.001), which modulates the compensatory response of the right ventricle, promoting the hypertrophy of contractile elements and limiting the areas in which fibrosis develops (p < 0.001).
CONCLUSIONS:
The subcutaneous infusion with osmotic pumps was a valid and reproducible method of delivering basic fibroblast growth factor to heart tissue. This infusion contributed to better preserve the right ventricular capillary network, hampering the development of interstitial fibrosis