Peripheral arterial disease and diabetes: effects on endothelial progenitor cell differentiation and nitric oxide metabolism

In the recent years it is emerged that peripheral arterial disease (PAD) has become a growing health problem in Western countries. This is a progressive manifestation of atherothrombotic vascular disease, which results into the narrowing of the blood vessels of the lower limbs and, as final consequence, in critical leg ischemia. PAD often occurs along with other cardiovascular risk factors, including diabetes mellitus (DM), low-grade inflammation, hypertension, and lipid disorders. Patients with DM have an increased risk of developing PAD, and that risk increases with the duration of DM. Moreover, there is a growing population of patients identified with insulin resistance (IR), impaired glucose tolerance, and obesity, a pathological condition known as “metabolic syndrome”, which presents increased cardiovascular risk. Atherosclerosis is the earliest symptom of PAD and is a dynamic and progressive disease arising from the combination of endothelial dysfunction and inflammation. Endothelial dysfunction is a broad term that implies diminished production or availability of nitric oxide (NO) and/or an imbalance in the relative contribution of endothelium-derived relaxing factors. The secretion of these agents is considerably reduced in association with the major risks of atherosclerosis, especially hyperglycaemia and diabetes, and a reduced vascular repair has been observed in response to wound healing and to ischemia. Neovascularization does not only rely on the proliferation of local endothelial cells, but also involves bone marrow-derived stem cells, referred to as endothelial progenitor cells (EPCs), since they exhibit endothelial surface markers and properties. They can promote postnatal vasculogenesis by homing to, differentiating into an endothelial phenotype, proliferating and incorporating into new vessels. Consequently, EPCs are critical to endothelium maintenance and repair and their dysfunction contributes to vascular disease. The aim of this study has been the characterization of EPCs from healthy peripheral blood, in terms of proliferation, differentiation and function. Given the importance of NO in neovascularization and homing process, it has been investigated the expression of NO synthase (NOS) isoforms, eNOS, nNOS and iNOS, and the effects of their inhibition on EPC function. Moreover, it has been examined the expression of NADPH oxidase (Nox) isoforms which are the principal source of ROS in the cell. In fact, a number of evidences showed the correlation between ROS and NO metabolism, since oxidative stress causes NOS inactivation via enzyme uncoupling. In particular, it has been studied the expression of Nox2 and Nox4, constitutively expressed in endothelium, and Nox1. The second part of this research was focused on the study of EPCs under pathological conditions. Firstly, EPCs isolated from healthy subject were cultured in a hyperglycaemic medium, in order to evaluate the effects of high glucose concentration on EPCs. Secondly, EPCs were isolated from the peripheral blood of patients affected with PAD, both diabetic or not, and it was assessed their capacity to proliferate, differentiate, and to participate to neovasculogenesis. Furthermore, it was investigated the expression of NOS and Nox in these cells. Mononuclear cells isolated from peripheral blood of healthy patients, if cultured under differentiating conditions, differentiate into EPCs. These cells are not able to form capillary-like structures ex novo, but participate to vasculogenesis by incorporation into the new vessels formed by mature endothelial cells, such as HUVECs. With respect to NOS expression, these cells have high levels of iNOS, the inducible isoform of NOS, 3-4 fold higher than in HUVECs. While the endothelial isoform, eNOS, is poorly expressed in EPCs. The higher iNOS expression could be a form of compensation of lower eNOS levels. Under hyperglycaemic conditions, both iNOS and eNOS expression are enhanced compared to control EPCs, as resulted from experimental studies in animal models. In patients affected with PAD, the EPCs may act in different ways. Non-diabetic patients and diabetic patients with a higher vascular damage, evidenced by a higher number of circulating endothelial cells (CECs), show a reduced proliferation and ability to participate to vasculogenesis. On the other hand, diabetic patients with lower CEC number have proliferative and vasculogenic capacity more similar to healthy EPCs. eNOS levels in both patient types are equivalent to those of control, while iNOS expression is enhanced. Interestingly, nNOS is not detected in diabetic patients, analogously to other cell types in diabetics, which show a reduced or no nNOS expression. Concerning Nox expression, EPCs present higher levels of both Nox1 and Nox2, in comparison with HUVECs, while Nox4 is poorly expressed, probably because of uncompleted differentiation into an endothelial phenotype. Nox1 is more expressed in PAD patients, diabetic or not, than in controls, suggesting an increased ROS production. Nox2, instead, is lower in patients than in controls. Being Nox2 involved in cellular response to VEGF, its reduced expression can be referable to impaired vasculogenic potential of PAD patients.

Evaluation of bone strength: microtomographic tecniques

This thesis is a part of a larger study about the characterization of mechanical and histomorphometrical properties of bone. The main objects of this study were the bone tissue properties and its resistance to mechanical loads. Moreover, the knowledge about the equipment selected to carry out the analyses, the micro-computed tomography (micro-CT), was improved. Particular attention was given to the reliability over time of the measuring instrument. In order to understand the main characteristics of bone mechanical properties a study of the skeletal, the bones of which it is composed and biological principles that drive their formation and remodelling, was necessary. This study has led to the definition of two macro-classes describing the main components responsible for the resistance to fracture of bone: quantity and quality of bone. The study of bone quantity is the current clinical standard measure for so-called bone densitometry, and research studies have amply demonstrated that the amount of tissue is correlated with its mechanical properties of elasticity and fracture. However, the models presented in the literature, including information on the mere quantity of tissue, have often been limited in describing the mechanical behaviour. Recent investigations have underlined that also the bone-structure and the tissue-mineralization play an important role in the mechanical characterization of bone tissue. For this reason in this thesis the class defined as bone quality was mainly studied, splitting it into two sub-classes of bone structure and tissue quality. A study on bone structure was designed to identify which structural parameters, among the several presented in the literature, could be integrated with the information about quantity, in order to better describe the mechanical properties of bone. In this way, it was also possible to analyse the iteration between structure and function. It has been known for long that bone tissue is capable of remodeling and changing its internal structure according to loads, but the dynamics of these changes are still being analysed. This part of the study was aimed to identify the parameters that could quantify the structural changes of bone tissue during the development of a given disease: osteoarthritis. A study on tissue quality would have to be divided into different classes, which would require a scale of analysis not suitable for the micro-CT. For this reason the study was focused only on the mineralization of the tissue, highlighting the difference between bone density and tissue density, working in a context where there is still an ongoing scientific debate.

Bioinspired fabrication of biosilica-based bone substitution materials

Until today, autogenic bone grafts from various donor regions represent the gold standard in the field of bone reconstruction, providing both osteoinductive and osteoconductive characteristics. However, due to low availability and a disequilibrium between supply and demand, the risk of disease transfer and morbidity, usually associated with autogeneic bone grafts, the development of biomimic materials with structural and chemical properties similar to those of natural bone have been extensively studied. So far,rnonly a few synthetic materials, so far, have met these criteria, displaying properties that allow an optimal bone reconstitution. Biosilica is formed enzymatically under physiological-relevant conditions (temperature and pH) via silicatein (silica protein), an enzyme that was isolated from siliceous sponges, cloned, and prepared in a recombinant way, retaining its catalytic activity. It is biocompatible, has some unique mechanical characteristics, and comprises significant osteoinductive activity.rnTo explore the application of biosilica in the fields of regenerative medicine,rnsilicatein was encapsulated, together with its substrate sodium metasilicate, into poly(D,L-lactide)/polyvinylpyrrolidone(PVP)-based microspheres, using w/o/wrnmethodology with solvent casting and termed Poly(D,L-lactide)-silicatein silicacontaining-microspheres [PLASSM]. Both silicatein encapsulation efficiency (40%) and catalytic activity retention upon polymer encapsulation were enhanced by addition of an essential pre-emulsifying step using PVP. Furthermore, the metabolic stability, cytoxicity as well as the kinetics of silicatein release from the PLASSM were studied under biomimetic conditions, using simulated body fluid. As a solid support for PLASSM, a polyvinylpyrrolidone/starch/Na2HPO4-based matrix (termed plastic-like filler matrix containing silicic acid [PMSA]) was developed and its chemical and physical properties determined. Moreover, due to the non-toxicity and bioinactivity of the PMSA, it is suggested that PMSA acts as osteoconductive material. Both components, PLASSM and PMSA, when added together, form arnbifunctional 2-component implant material, that is (i)non-toxic(biocompatible), (ii)moldable, (iii) self-hardening at a controlled and clinically suitable rate to allows a tight insertion into any bone defect (iv) biodegradable, (v)forms a porous material upon exposure to body biomimetic conditions, and (vi)displays both osteoinductive (silicatein)and osteoconductive (PMSA) properties.rnPreliminary in vivo experiments were carried out with rabbit femurs, by creatingrnartificial bone defects that were subsequently treated with the bifunctional 2-component implant material. After 9 weeks of implantation, both computed tomography (CT) and morphological analyses showed complete resorption of the implanted material, concurrent with complete bone regeneration. The given data can be considered as a significant contribution to the successful introduction of biosilica-based implants into the field of bone substitution surgery.

Evaluation of Antitumoral activity of bone targeted drugs/conventional chemotherapies and identification of biomarkers for the selection of patients with breast cancer for the bone targeted therapy in adjuvant setting

Bone metastases are responsible for different clinical complications defined as skeletal-related events (SREs) such as pathologic fractures, spinal cord compression, hypercalcaemia, bone marrow infiltration and severe bone pain requiring palliative radiotherapy. The general aim of these three years research period was to improve the management of patients with bone metastases through two different approaches of translational research. Firstly in vitro preclinical tests were conducted on breast cancer cells and on indirect co-colture of cancer cells and osteoclasts to evaluate bone targeted therapy singly and in combination with conventional chemotherapy. The study suggests that zoledronic acid has an antitumor activity in breast cancer cell lines. Its mechanism of action involves the decrease of RAS and RHO, as in osteoclasts. Repeated treatment enhances antitumor activity compared to non-repeated treatment. Furthermore the combination Zoledronic Acid + Cisplatin induced a high antitumoral activity in the two triple-negative lines MDA-MB-231 and BRC-230. The p21, pMAPK and m-TOR pathways were regulated by this combined treatment, particularly at lower Cisplatin doses. A co-colture system to test the activity of bone-targeted molecules on monocytes-breast conditioned by breast cancer cells was also developed. Another important criticism of the treatment of breast cancer patients, is the selection of patients who will benefit of bone targeted therapy in the adjuvant setting. A retrospective case-control study on breast cancer patients to find new predictive markers of bone metastases in the primary tumors was performed. Eight markers were evaluated and TFF1 and CXCR4 were found to discriminate between patients with relapse to bone respect to patients with no evidence of disease. In particular TFF1 was the most accurate marker reaching a sensitivity of 63% and a specificity of 79%. This marker could be a useful tool for clinicians to select patients who could benefit for bone targeted therapy in adjuvant setting.

Circulating Fibrocytes, their role in renal fibrosis and molecular pathways involved. Possible biomarkers of fibrogenesis in chronic kidney disease

Circulating Fibrocytes (CFs) are bone marrow-derived mesenchymal progenitor cells that express a similar pattern of surface markers related to leukocytes, hematopoietic progenitor cells and fibroblasts. CFs precursor display an ability to differentiate into fibroblasts and Myofibroblasts, as well as adipocytes. Fibrocytes have been shown to contribute to tissue fibrosis in the end-stage renal disease (ESRD), as well as in other fibrotic diseases, leading to fibrogenic process in other organs including lung, cardiac, gut and liver. This evidence has been confirmed by several experimental proofs in mice models of kidney injury. In the present study, we developed a protocol for the study of CFs, by using peripheral blood monocytes cells (PBMCs) samples collected from healthy human volunteers. Thanks to a flow cytometry method, in vitro culture assays and the gene expression assays, we are able to study and characterize this CFs population. Moreover, results confirmed that these approaches are reliable and reproducible for the investigation of the circulating fibrocytes population in whole blood samples. Our final aim is to confirm the presence of a correlation between the renal fibrosis progression, and the different circulating fibrocyte levels in Chronic Kidney Disease (CKD) patients. Thanks to a protocol study presented and accepted by the Ethic Committee we are continuing the study of CFs induction in a cohort of sixty patients affected by CKD, divided in three distinct groups for different glomerular filtration rate (GFR) levels, plus a control group of thirty healthy subjects. Ongoing experiments will determine whether circulating fibrocytes represent novel biomarkers for the study of CKD progression, in the early and late phases of this disease.

Macrocyclic bisphosphonates for PET-diagnosis and endoradiotherapy of bone metastases

Die Fallzahlen von Prostata- und Brustkrebs nehmen aktuell die Spitzenplätze bei Krebserkrankungen weltweit ein. Eine schwerwiegende Folge dieser Erkrankung stellen Metastasierungen in das Knochengewebe dar, welche zu einer dramatischen Verschlechterung des Allgemeinzustandes und der Lebensqualität des Patienten führen. Die Symptome sind gekennzeichnet durch enorme Schmerzen in Kombination mit osteoblastischen und osteolytischen Knochenveränderungen, bis hin zu Frakturen und spinalen Kompressionssyndromen, sowie einer metabolischen Hypercalcaemie.rnBei der Diagnose und Therapie nehmen verschiedene Radiopharmaka eine Schlüsselrolle ein. Konjugate aus makrozyklischen Chelatoren und knochenaffinen Bisphosphonaten stellen ein geeignetes Mittel dar als so genannte Theranostika, die Diagnose und Therapie in einem Molekül vereinen. Hierbei konnten mit dem Generator basierenden PET-Nuklid 68Ga(III) und dem Therapienuklid 177Lu(III) erste Erfolge mit der Verbindung BPAMD am Patienten erzielt werden. Im Rahmen der vorliegenden Arbeit ist es gelungen, die pharmakologischen Eigenschaften der BPAMD-Leitstruktur weiter zu optimieren und neue Derivate erfolgreich zu synthetisieren. Diese zeichneten sich durch eine erhöhte Knochenaffinität und eines besseren ´target to background´ Verhältnisses aus. Im Zuge der Derivatisierung ist es außerdem gelungen, erfolgreich eine Substanz darzustellen, welche über eine gesteigerte Blutretention verfügt und die letztendlich die Bioverfügbarkeit des Tracers erhöhte. Verbindungen solchen Typs können zu einem besseren Tumor zu gesundem Knochen Verhältnis beitragen und eventuell einen höheren Therapieerfolg erzielen. Eines dieser neuen vielversprechenden Bisphosphonate, [68Ga]NO2APBP konnte innerhalb einer klinischen Phase 0 bzw. I sein großes Potential als Diagnostikum zur Erfassung von Skelettmetastasen unter Beweis stellen. Innerhalb einer Testreihe mit 12 Patienten wurde eine hohe diagnostische Übereinstimmung mit dem Goldstandard 18F-Fluorid erreicht. In ausgesuchten Metastasen konnte sogar eine höhere Tracer-Aufnahme erzielt werden.rnIn Zukunft können makrozyklische Bisphosphonate eine wichtige Rolle bei der palliativen Schmerztherapie von Knochenmetastasen einnehmen. rn

Abnormal bone geometry at the metacarpal bone shaft of rheumatoid arthritis patients with maintained muscle-bone relationship

OBJECTIVES:: Metacarpal juxta-articular bone is altered in Rheumatoid Arthritis (RA). However, a detailed analysis of disease related geometrical adaptations of the metacarpal shaft is missing. The aim of the present study was to assess the role of RA disease, forearm muscle cross-sectional area (CSA), age and sex on bone geometry at the metacarpal shaft. METHODS:: In 64 RA patients and 128 control subjects geometric properties of the third metacarpal bone mid-shaft and forearm muscle CSA were measured by peripheral quantitative computed tomography (pQCT). Linear models were performed for cortical CSA, total bone CSA, polar stress-strain Index (polar SSI, a surrogate for bone's resistance to bending and torsion), cortical thickness and Metacarpal Index (MI=cortical CSA/total CSA) with explanatory variables muscle CSA, age, RA status and sex. RESULTS:: Forearm muscle CSA was associated with cortical and total metacarpal CSA, and polar SSI. RA group status was associated with all bone parameters except cortical CSA. There was a significant interaction between RA status and age, indicating that the RA group had a greater age-related decrease in cortical CSA, cortical thickness and MI. CONCLUSIONS:: Bone geometry of the metacarpal shaft is altered in RA patients compared to healthy controls. While bone mass of the metacarpal shaft is adapted to forearm muscle mass, cortical thickness and MI are reduced but outer bone shaft circumference and polar SSI increased in RA patients. These adaptations correspond to an enhanced aging pattern in RA patients.

Reduced trabecular bone mineral density and cortical thickness accompanied by increased outer bone circumference in metacarpal bone of rheumatoid arthritis patients: a cross-sectional study

Introduction The objective of this study was to assess three-dimensional bone geometry and density at the epiphysis and shaft of the third meta-carpal bone of rheumatoid arthritis (RA) patients in comparison to healthy controls with the novel method of peripheral quantitative computed tomography (pQCT). Methods PQCT scans were performed in 50 female RA patients and 100 healthy female controls at the distal epiphyses and shafts of the third metacarpal bone, the radius and the tibia. Reproducibility was determined by coefficient of varia-tion. Bone densitometric and geometric parameters were compared between the two groups and correlated to disease characteristics. Results Reproducibility of different pQCT parameters was between 0.7% and 2.5%. RA patients had 12% to 19% lower trabecular bone mineral density (BMD) (P ≤ 0.001) at the distal epiphyses of radius, tibia and metacarpal bone. At the shafts of these bones RA patients had 7% to 16% thinner cortices (P ≤ 0.03). Total cross-sectional area (CSA) at the metacarpal bone shaft of pa-tients was larger (between 5% and 7%, P < 0.02), and relative cortical area was reduced by 13%. Erosiveness by Ratingen score correlated negatively with tra-becular and total BMD at the epiphyses and shaft cortical thickness of all measured bones (P < 0.04). Conclusions Reduced trabecular BMD and thinner cortices at peripheral bones, and a greater bone shaft diameter at the metacarpal bone suggest RA spe-cific bone alterations. The proposed pQCT protocol is reliable and allows measuring juxta-articular trabecular BMD and shaft geometry at the metacarpal bone.

Intraarterial administration of bone marrow mononuclear cells in patients with critical limb ischemia: a randomized-start, placebo-controlled pilot trial (PROVASA)

Critical limb ischemia due to peripheral arterial occlusive disease is associated with a severely increased morbidity and mortality. There is no effective pharmacological therapy available. Injection of autologous bone marrow-derived mononuclear cells (BM-MNC) is a promising therapeutic option in patients with critical limb ischemia, but double-blind, randomized trials are lacking.

Saliva/pathogen biomarker signatures and periodontal disease progression

The purpose of this study was to determine the role of saliva-derived biomarkers and periodontal pathogens during periodontal disease progression (PDP). One hundred human participants were recruited into a 12-month investigation. They were seen bi-monthly for saliva and clinical measures and bi-annually for subtraction radiography, serum and plaque biofilm assessments. Saliva and serum were analyzed with protein arrays for 14 pro-inflammatory and bone turnover markers, while qPCR was used for detection of biofilm. A hierarchical clustering algorithm was used to group study participants based on clinical, microbiological, salivary/serum biomarkers, and PDP. Eighty-three individuals completed the six-month monitoring phase, with 39 [corrected] exhibiting PDP, while 44 [corrected] demonstrated stability. Participants assembled into three clusters based on periodontal pathogens, serum and salivary biomarkers. Cluster 1 members displayed high salivary biomarkers and biofilm; 71% [corrected] of these individuals were undergoing PDP. Cluster 2 members displayed low biofilm and biomarker levels; 76% [corrected] of these individuals were stable. Cluster 3 members were not discriminated by PDP status; however, cluster stratification followed groups 1 and 2 based on thresholds of salivary biomarkers and biofilm pathogens. The association of cluster membership to PDP was highly significant (p < 0.0007). [corrected] The use of salivary and biofilm biomarkers offers potential for the identification of PDP or stability (ClinicalTrials.gov number, CT00277745).

Early-Stage Primary Bone Lymphoma: A Retrospective, Multicenter Rare Cancer Network (RCN) Study

Primary bone lymphoma (PBL) represents less than 1% of all malignant lymphomas. In this study, we assessed the disease profile, outcome, and prognostic factors in patients with Stages I and II PBL.

CD27 signaling on chronic myelogenous leukemia stem cells activates Wnt target genes and promotes disease progression

Chronic myelogenous leukemia (CML) results from a chromosomal translocation in hematopoietic stem or early progenitor cells that gives rise to the oncogenic BCR/ABL fusion protein. Clinically, CML has a chronic phase that eventually evolves into an accelerated stage and blast crisis. A CML-specific immune response is thought to contribute to the control of disease. Whether the immune system can also promote disease progression is not known. In the present study, we investigated the possibility that the TNF receptor family member CD27 is present on leukemia stem cells (LSCs) and mediates effects of the immune system on CML. In a mouse model of CML, BCR/ABL+ LSCs and leukemia progenitor cells were found to express CD27. Binding of CD27 by its ligand, CD70, increased expression of Wnt target genes in LSCs by enhancing nuclear localization of active β-catenin and TRAF2- and NCK-interacting kinase (TNIK). This resulted in increased proliferation and differentiation of LSCs. Blocking CD27 signaling in LSCs delayed disease progression and prolonged survival. Furthermore, CD27 was expressed on CML stem/progenitor cells in the bone marrow of CML patients, and CD27 signaling promoted growth of BCR/ABL+ human leukemia cells by activating the Wnt pathway. Since expression of CD70 is limited to activated lymphocytes and dendritic cells, our results reveal a mechanism by which adaptive immunity contributes to leukemia progression. In addition, targeting CD27 on LSCs may represent an attractive therapeutic approach to blocking the Wnt/β-catenin pathway in CML.

Stereologic analysis of tibial-plateau cartilage and femoral cancellous bone in guinea pigs with spontaneous osteoarthritis

Two strains of guinea pig develop spontaneous osteoarthritis of the knee. Although the disease evolves at different rates in the two strains, it is not known whether these differences are reflected in the structure of the cartilage and cancellous bone.

Incidence, predictive factors, and prognosis of chondrosarcoma in patients with Ollier disease and Maffucci syndrome: an international multicenter study of 161 patients

Enchondromatosis is characterized by the presence of multiple benign cartilage lesions in bone. While Ollier disease is typified by multiple enchondromas, in Maffucci syndrome these are associated with hemangiomas. Studies evaluating the predictive value of clinical symptoms for development of secondary chondrosarcoma and prognosis are lacking. This multi-institute study evaluates the clinical characteristics of patients, to get better insight on behavior and prognosis of these diseases.

Atypical transmissible spongiform encephalopathies in ruminants: a challenge for disease surveillance and control

Since 1987, when bovine spongiform encephalopathy (BSE) emerged as a novel disease in cattle, enormous efforts were undertaken to monitor and control the disease in ruminants worldwide. The driving force was its high economic impact, which resulted from trade restrictions and the loss of consumer confidence in beef products, the latter because BSE turned out to be a fatal zoonosis, causing variant Creutzfeldt-Jakob disease in human beings. The ban on meat and bone meal in livestock feed and the removal of specified risk materials from the food chain were the main measures to successfully prevent infection in cattle and to protect human beings from BSE exposure. However, although BSE is now under control, previously unknown, so-called atypical transmissible spongiform encephalopathies (TSEs) in cattle and small ruminants have been identified by enhanced disease surveillance. This report briefly reviews and summarizes the current level of knowledge on the spectrum of TSEs in cattle and small ruminants and addresses the question of the extent to which such atypical TSEs have an effect on disease surveillance and control strategies.