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Background Paediatric acute myeloid leukaemia (AML) is characterized by poor outcomes in patients with relapsed/refractory disease, despite the improvements in intensive standard therapy. The leukaemic cells of paediatric AML patients show high expression of the CD123 antigen, and this finding provides the biological basis to target CD123 with the chimeric antigen receptor (CAR). However, CAR.CD123 therapy in AML is hampered by on-target off-tumour toxicity and a long “vein-to-vein” time. Methods We developed an off-the-shelf product based on allogeneic natural killer (NK) cells derived from the peripheral blood of healthy donors and engineered them to express a second-generation CAR targeting CD123 (CAR.CD123). Results CAR.CD123-NK cells showed significant anti-leukaemia activity not only in vitro against CD123+ AML cell lines and CD123+ primary blasts but also in two animal models of human AML-bearing immune-deficient mice. Data on anti-leukaemia activity were also corroborated by the quantification of inflammatory cytokines, namely granzyme B (Granz B), interferon gamma (IFN-γ) and tumour necrosis factor alpha (TNF-α), both in vitro and in the plasma of mice treated with CAR.CD123-NK cells. To evaluate and compare the on-target off-tumour effects of CAR.CD123-T and NK cells, we engrafted human haematopoietic cells (hHCs) in an immune-deficient mouse model. All mice infused with CAR.CD123-T cells died by Day 5, developing toxicity against primary human bone marrow (BM) cells with a decreased number of total hCD45+ cells and, in particular, of hCD34+CD38− stem cells. In contrast, treatment with CAR.CD123-NK cells was not associated with toxicity, and all mice were alive at the end of the experiments. Finally, in a mouse model engrafted with human endothelial tissues, we demonstrated that CAR.CD123-NK cells were characterized by negligible endothelial toxicity when compared to CAR.CD123-T cells. Conclusions Our data indicate the feasibility of an innovative off-the-shelf therapeutic strategy based on CAR.CD123-NK cells, characterized by remarkable efficacy and an improved safety profile compared to CAR.CD123-T cells. These findings open a novel intriguing scenario not only for the treatment of refractory/resistant AML patients but also to further investigate the use of CAR-NK cells in other cancers characterized by highly difficult targeting with the most conventional T effector cells.

Mucopolysaccharidosis type I (MPSI) (OMIM #252800) is an autosomal recessive disorder caused by pathogenic variants in the IDUA gene encoding for the lysosomal alpha-L-iduronidase enzyme. The deficiency of this enzyme causes systemic accumulation of glycosaminoglycans (GAGs). Although disease manifestations are typically not apparent at birth, they can present early in life, are progressive, and include a wide spectrum of phenotypic findings. Among these, the storage of GAGs within the lysosomes disrupts cell function and metabolism in the cartilage, thus impairing normal bone development and ossification. Skeletal manifestations of MPSI are often refractory to treatment and severely affect patients’ quality of life. This review discusses the pathological and molecular processes leading to impaired endochondral ossification in MPSI patients and the limitations of current therapeutic approaches. Understanding the underlying mechanisms responsible for the skeletal phenotype in MPSI patients is crucial, as it could lead to the development of new therapeutic strategies targeting the skeletal abnormalities of MPSI in the early stages of the disease.

The bone marrow adipose tissue constitutes more than two-thirds of the bone marrow volume in adult life and is known to have unique metabolic and functional properties. In neoplastic disorders, bone marrow adipocytes (BMAds) contribute to create a favorable microenvironment to survival and proliferation of cancer cells. Many studies explored the molecular crosstalk between BMAds and neoplastic cells, predominantly in ex-vivo experimental systems or in animal models. However, little is known on the features of BMAds in the human neoplastic marrow. The aim of our study was to analyze the in situ changes in morphology and immunophenotype of BMAds in two different types of neoplastic marrow conditions. We selected a series of archival iliac crest and vertebral bone biopsies from patients with bone marrow metastasis (MET), patients with myeloproliferative neoplasia with grade-3 myelofibrosis (MPN-MF) and age-matched controls (CTR). We observed a significant reduction in the number of BMAds in MET and MPN-MF compared to CTR. Accordingly, in the same groups, we also detected a significant reduction in the mean cell diameter and area. Immunolocalization of different adipocyte markers showed that, compared to CTR, in both MET and MPN-MF the percentages of adiponectin- and phosphorylated hormone sensitive lipase-positive BMAds were significantly reduced and increased respectively. No statistically significant difference was found between MET and MPN-MF. Interestingly, in one MET sample, “remodeled” BMAds containing a large lipid vacuole and multiple, smaller and polarized lipid droplets were identified. In conclusion, our data show that in different types of marrow cancers, BMAds undergo significant quantitative and qualitative changes, which need to be further investigated in future studies.

Renal allograft recipients are at greater risk of developing tuberculosis than the general population. A woman with a kidney transplant was admitted to the emergency department with high temperature, dysphonia, odynophagia, and asthenia. The final diagnosis was laryngeal tuberculosis. Multidisciplinary collaboration enabled accurate diagnosis and successful treatment. Laryngeal tuberculosis should be considered in renal allograft recipients with hoarseness. A more rapid diagnosis of tuberculosis in renal transplant recipients is desirable when the site involved, such as the larynx, exhibits specific manifestations and the patient exhibits specific symptoms. In these cases, prognosis is excellent, and with adequate treatment, a complete recovery is often achieved.

Background Liver involvement in adults with acute myeloid leukemia is uncommon. Most of the case reports describe acute liver failure or obstructive jaundice, while acute hepatitis is rarely mentioned. We report a patient with acute myeloid leukemia who presented with clinical, biochemical, and radiological signs of acute hepatitis that totally regressed after chemotherapy. Case presentation A 38-year-old Caucasian man presented with fever, cough, and mild fatigue. Laboratory workup showed anemia, thrombocytopenia, severe leukocytosis, transaminitis, and hyperbilirubinemia. Imaging of the abdomen (ultrasound and magnetic resonance) showed hepatomegaly, splenomegaly, upper limits portal veins diameters, increased thickness of the gallbladder wall, and significant abdominal lymph nodes. Peripheral blood smear and bone marrow evaluation were consistent with acute myeloid leukemia, and liver biopsy showed massive sinusoidal and portal infiltration by leukemic cells. After remission-inducing chemotherapy, there was complete normalization of liver function tests, and liver, spleen, and portal vein size. Conclusions This case highlights the importance of taking acute myeloid leukemia into account as a possible cause of liver damage to make a rapid diagnosis and start appropriate treatment that may lead to hematological remission and hepatic dysfunction resolution.

In nonalcoholic steatohepatitis animal models, an increased lipid droplet size in hepatocytes is associated with fibrogenesis. Hepatocytes with large droplet (Ld-MaS) or small droplet (Sd-MaS) macrovesicular steatosis may coexist in the human liver, but the factors associated with the predominance of one type over the other, including hepatic fibrogenic capacity, are unknown. In pre-ischemic liver biopsies from 225 consecutive liver transplant donors, we retrospectively counted hepatocytes with Ld-MaS and Sd-MaS and defined the predominant type of steatosis as involving ≥50% of steatotic hepatocytes. We analyzed a donor Patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 polymorphism, hepatic expression of proteins involved in lipid metabolism by RT-PCR, hepatic stellate cell (HSC) activation by α-SMA immunohistochemistry and, one year after transplantation, histological progression of fibrosis due to Hepatitis C Virus (HCV) recurrence. Seventy-four livers had no steatosis, and there were 98 and 53 with predominant Ld-MaS and Sd-MaS, respectively. In linear regression models, adjusted for many donor variables, the percentage of steatotic hepatocytes affected by Ld-MaS was inversely associated with hepatic expression of Insulin Induced Gene 1 (INSIG-1) and Niemann-Pick C1-Like 1 gene (NPC1L1) and directly with donor PNPLA3 variant M, HSC activation and progression of post-transplant fibrosis. In humans, Ld-MaS formation by hepatocytes is associated with abnormal PNPLA3-mediated lipolysis, downregulation of both the intracellular cholesterol sensor and cholesterol reabsorption from bile and increased hepatic fibrogenesis.

Isolated primary cutaneous amyloidosis (PCA) of the external ear is extremely rare. We describe the case of a 65-year-old woman presenting with itching within the left external auditory canal (EAC). Otoscopy revealed a 3 mm whitish lesion involving the cartilaginous portion of the left EAC. The lesion was excised. Histological and immunohistochemical features were consistent with keratinic amyloidosis. A clinical workup was negative for systemic amyloidosis. As far as we know, only nine cases of PCA exclusively involving the EAC have been reported. The frequent occurrence of itching in these patients and the keratinic nature of the amyloid support the role of chronic stimulation/irritation in the pathogenesis of isolated amyloidosis the EAC.

Populations of bone marrow stromal cells (BMSCs, also known as bone marrow-derived "mesenchymal stem cells") contain a subset of cells that are able to recapitulate the formation of a bone/marrow organ (skeletal stem cells, SSCs). It is now apparent that cells with similar but not identical properties can be isolated from other skeletal compartments (growth plate, periosteum). The biological properties of BMSCs, and these related stem/progenitor cells, are assessed by a variety of assays, both in vitro and in vivo. Application of these assays in an appropriate fashion provide a great deal of information on the role of BMSCs, and the subset of SSCs, in health and in disease.

Bone formation starts near the end of the embryonic stage of development and continues throughout life during bone modeling and growth, remodeling, and when needed, regeneration. Bone-forming cells, traditionally termed osteoblasts, produce, assemble, and control the mineralization of the type I collagen-enriched bone matrix while participating in the regulation of other cell processes, such as osteoclastogenesis, and metabolic activities, such as phosphate homeostasis. Osteoblasts are generated by different cohorts of skeletal stem cells that arise from different embryonic specifications, which operate in the pre-natal and/or adult skeleton under the control of multiple regulators. In this review, we briefly define the cellular identity and function of osteoblasts and discuss the main populations of osteoprogenitor cells identified to date. We also provide examples of long-known and recently recognized regulatory pathways and mechanisms involved in the specification of the osteogenic lineage, as assessed by studies on mice models and human genetic skeletal diseases.

Carcinoma cuniculatum (CC) is a rare clinicopathologic variant of squamous cell carcinoma. Histologically, it is characterized by invasive growth of bland, acanthotic, and keratinizing squamous epithelium that forms multiple rabbit burrow-like, keratin-filled crypts and sinuses. We present a 51-year-old male smoker with CC of the left vocal cord. The tumor was staged T1a and the patient was disease-free 12 months after surgery. To our knowledge, this is the fourth case of CC of the larynx reported in the English literature and the first, due to its early diagnosis, where radical surgery was not performed. We highlight the necessity for awareness of this entity and coordination between otolaryngologists, radiologists, and pathologists for early diagnosis and organ-sparing surgical treatment.

Populations of bone marrow stromal cells (BMSCs, also known as bone marrow-derived "mesenchymal stem cells") contain a subset of cells that are able to recapitulate the formation of a bone/marrow organ (skeletal stem cells, SSCs). It is now apparent that cells with similar but not identical properties can be isolated from other skeletal compartments (growth plate, periosteum). The biological properties of BMSCs, and these related stem/progenitor cells, are assessed by a variety of assays, both in vitro and in vivo. Application of these assays in an appropriate fashion provide a great deal of information on the role of BMSCs, and the subset of SSCs, in health and in disease.

Fibrous dysplasia may show locally aggressive behaviour reflecting secondary intralesional changes, extension to soft tissue, or malignant transformation. We report the case of a patient with polyostotic fibrous dysplasia who had a giant mandibular lesion consisting of histologically typical, genotypically-confirmed, fibrous dysplasia merged with a fibrotic and hypocellular desmoplastic fibroma-like tissue in which the same Gsα-R201H mutation was detected. The occurrence of the same mutation in both the fibrous dysplasia and areas of desmoplastic fibroma suggests that the fibroma-like tissue reflects an unusual secondary tissue change within an otherwise typical fibrous dysplasia. To the best of our knowledge, only four cases of fibrous dysplasia with desmoplastic fibroma-like tissue changes have been reported.

Fibrous dysplasia (FD) of bone is a complex disease of the skeleton caused by dominant activating mutations of the GNAS locus encoding for the α subunit of the G protein-coupled receptor complex (Gsα). The mutation involves a substitution of arginine at position 201 by histidine or cysteine (GsαR201H or R201C), which leads to overproduction of cAMP. Several signaling pathways are implicated downstream of excess cAMP in the manifestation of disease. However, the pathogenesis of FD remains largely unknown. The overall FD phenotype can be attributed to alterations of skeletal stem/progenitor cells which normally develop into osteogenic or adipogenic cells (in cis), and are also known to provide support to angiogenesis, hematopoiesis, and osteoclastogenesis (in trans). In order to dissect the molecular pathways rooted in skeletal stem/progenitor cells by FD mutations, we engineered human skeletal stem/progenitor cells with the GsαR201C mutation and performed transcriptomic analysis. Our data suggest that this FD mutation profoundly alters the properties of skeletal stem/progenitor cells by pushing them towards formation of disorganized bone with a concomitant alteration of adipogenic differentiation. In addition, the mutation creates an altered in trans environment that induces neovascularization, cytokine/chemokine changes and osteoclastogenesis. In silico comparison of our data with the signature of FD craniofacial samples highlighted common traits, such as the upregulation of ADAM (A Disintegrin and Metalloprotease) proteins and other matrix-related factors, and of PDE7B (Phosphodiesterase 7B), which can be considered as a buffering process, activated to compensate for excess cAMP. We also observed high levels of CEBPs (CCAAT-Enhancer Binding Proteins) in both data sets, factors related to browning of white fat. This is the first analysis of the reaction of human skeletal stem/progenitor cells to the introduction of the FD mutation and we believe it provides a useful background for further studies on the molecular basis of the disease and for the identification of novel potential therapeutic targets. Published version

Mesenchymal stromal cells (MSCs) represent an essential component of the bone marrow (BM) niche and display disease-specific alterations in several myeloid malignancies. The aim of this work was to study possible MSC abnormalities in Philadelphia-negative myeloproliferative neoplasms (MPNs) in relationship to the degree of BM fibrosis. MSCs were isolated from BM of 6 healthy donors (HD) and of 23 MPN patients, classified in 3 groups according to the diagnosis and the grade of BM fibrosis: polycythemia vera and essential thrombocythemia (PV/ET), low fibrosis myelofibrosis (LF-MF), and high fibrosis MF (HF-MF). MSC cultures were established from 21 of 23 MPN patients. MPN-derived MSCs did not exhibit any functional impairment in their adipogenic/osteogenic/chondrogenic differentiation potential and displayed a phenotype similar to HD-derived MSCs but with a decreased expression of CD146. All MPN-MSC lines were negative for the patient-specific hematopoietic clone mutations (JAK2, MPL, CALR). MSCs derived from HF-MF patients displayed a reduced clonogenic potential and a lower growth kinetic compared to MSCs from HD, LF-MF, and PV/ET patients. mRNA levels of hematopoiesis regulatory molecules were unaffected in MSCs from HF-MF compared to HD. Finally, in vitro ActivinA secretion by MSCs was increased in HF-MF compared to LF-MF patients, in association with a lower hemoglobin value. Increased ActivinA immunolabeling on stromal cells and erythroid precursors was also observed in HF-MF BM biopsies. In conclusion, higher grade of BM fibrosis is associated with functional impairment of MSCs and the increased secretion of ActivinA may represent a suitable target for anemia treatment in MF patients.

Summary Heterotopia of liver tissue is uncommon. It has been reported at various sites, more frequently near the orthotopic liver, including gallbladder, hepatic ligaments, omentum, and retroperitoneum, rarely within the diaphragm and the thoracic cavity, and never within the head. We report here a 22-year-old patient surgically treated for a maxillary osteosarcoma in which microscopic liver tissue islands were incidentally detected in the respiratory mucosa of the surgical margin. The islands comprised well-differentiated HepPar-1–positive hepatocytes and were surrounded by cytokeratin-7– and cytokeratin-19–positive bile duct–like structures. This case, which is unique in the medical literature, may suggest an inductive paracrine effect of the osteosarcoma cells by secretion of factors promoting hepatocyte specification of primitive endodermal progenitors and subsequent liver morphogenesis.

Fibrous dysplasia of bone/McCune-Albright syndrome (Polyostotic FD/MAS; OMIM#174800) is a crippling skeletal disease caused by gain-of-function mutations of Gs α. Enhanced bone resorption is a recurrent histological feature of FD and a major cause of fragility of affected bones. Previous work suggests that increased bone resorption in FD is driven by RANKL and some studies have shown that the anti-RANKL monoclonal antibody, denosumab, reduces bone turnover and bone pain in FD patients. However, the effect of RANKL inhibition on the histopathology of FD and its impact on the natural history of the disease remain to be assessed. In this study, we treated the EF1α-Gs αR201C mice, which develop an FD-like phenotype, with an anti-mouse RANKL monoclonal antibody. We found that the treatment induced marked radiographic and microscopic changes at affected skeletal sites in 2-month-old mice. The involved skeletal segments became sclerotic due to the deposition of new, highly mineralized bone within developing FD lesions and showed a higher mechanical resistance compared to affected segments from untreated transgenic mice. Similar changes were also detected in older mice with a full-blown skeletal phenotype. The administration of anti-mouse RANKL antibody arrested the growth of established lesions and, in young mice, prevented the appearance of new ones. However, after drug withdrawal, the newly formed bone was remodelled into FD tissue and the disease progression resumed in young mice. Taken together, our results show that the anti-RANKL antibody significantly affected the bone pathology and natural history of FD in the mouse. Pending further work on the prevention and management of relapse after treatment discontinuation, our preclinical study suggests that RANKL inhibition may be an effective therapeutic option for FD patients. © 2019 American Society for Bone and Mineral Research.

The mechanisms whereby autoreactive T cells escape peripheral tolerance establishing thus autoimmune diseases in humans remain an unresolved question. Here, we demonstrate that autoreactive polyfunctional CD8

Background. No data are available on liver transplantation (LT) outcome and donor liver steatosis, classified as large droplet macrovesicular (Ld-MaS), small-droplet macrovesicular (Sd-MaS), and true microvesicular (MiS), taking into account the recipient Hepatitis C virus (HCV) status. Aim. We investigate the impact of allograft steatosis reclassified according to the Brunt classification on early graft function and survival after LT. Methods. We retrospectively reviewed 204 consecutive preischemia biopsies of grafts transplanted in our center during the period 2001-2011 according to recipient HCV status. Results. The median follow-up after LT was 7.5 years (range: 0.0-16.7). In negative recipients (n=122), graft loss was independently associated with graft Sd-MaS, in multivariable Cox regression models comprehending only pre-/intraoperative variables (HR=1.03, 95%CI=1.01-1.05; P=0.003) and when including indexes of early postoperative graft function (HR=1.04, 95%CI=1.02-1.06; P=0.001). Graft Sd-MaS>15% showed a risk for graft loss > 2.5-folds in both the models. Graft Sd-MaS>15% was associated with reduced graft ATP content and, only in HCV- recipients, with higher early post-LT serum AST peaks. Conclusions. In HCV-negative recipients, allografts with >15% Sd-MaS have significantly reduced graft survival and show low ATP and higher AST peaks in the immediate posttransplant period. Donors with >15% Sd-MaS have significantly higher BMI, longer ICU stays, and lower PaO2.

Multiple non-ossifying fibromas (MNOFs) occur either isolated or in association with other anomalies, are usually localized in the long bones of the lower limbs, may be radiographically confused with other skeletal lesions, and tend to heal spontaneously with the completion of the skeletal growth. Segmental distribution, either monomelic or polymelic and ipsilateral, is rare and commonly observed in the context of developmental diseases known as "RASopathies", which are caused by mutations in genes that encode components or regulators within the Ras/mitogen-activated protein kinase signaling pathway. We describe here the radiographic and pathologic features of an 18-year-old Caucasian boy, whose clinical history started at the age of 3 when the diagnosis of aneurysmal bone cyst was made on a lytic lesion of his left clavicle. Over the following 2 years, the patient developed polyostotic and monomelic lesions within the left humerus, radius, and ulna. No other skeletal and extra-skeletal anomalies were clinically detected. The lesions were interpreted as consistent with polyostotic fibrous dysplasia and MNOFs and showed an unusually aggressive clinical course with progressive increase in size and coalescence. The definitive diagnosis of MNOFs was made after the exclusion of fibrous dysplasia by molecular analysis. The polyostotic and monomelic distribution of the lesions and the unusually aggressive clinical course contribute to make this case of MNOFs unique.

Summary A widely shared view reads that mesenchymal stem/stromal cells (“MSCs”) are ubiquitous in human connective tissues, can be defined by a common in vitro phenotype, share a skeletogenic potential as assessed by in vitro differentiation assays, and coincide with ubiquitous pericytes. Using stringent in vivo differentiation assays and transcriptome analysis, we show that human cell populations from different anatomical sources, regarded as “MSCs” based on these criteria and assumptions, actually differ widely in their transcriptomic signature and in vivo differentiation potential. In contrast, they share the capacity to guide the assembly of functional microvessels in vivo, regardless of their anatomical source, or in situ identity as perivascular or circulating cells. This analysis reveals that muscle pericytes, which are not spontaneously osteochondrogenic as previously claimed, may indeed coincide with an ectopic perivascular subset of committed myogenic cells similar to satellite cells. Cord blood-derived stromal cells, on the other hand, display the unique capacity to form cartilage in vivo spontaneously, in addition to an assayable osteogenic capacity. These data suggest the need to revise current misconceptions on the origin and function of so-called “MSCs,” with important applicative implications. The data also support the view that rather than a uniform class of “MSCs,” different mesoderm derivatives include distinct classes of tissue-specific committed progenitors, possibly of different developmental origin., Highlights • CD146+ “MSCs” from different tissues exhibit different transcriptional profiles • CD146+ “MSCs” from different tissues have different differentiation capacities • CD146+ “MSCs” from different tissues organize blood vessels and become pericytes, Bianco, Riminucci, Robey, and colleagues have provided evidence that “mesenchymal stem/stromal cells” (according to current “jargon”), derived from different sources (bone marrow, muscle, cord blood) vary widely in their transcriptional profile, and their differentiation capacity as assessed by in vitro assays and in vivo transplantation assays. Bone marrow “MSCs” form bone and support hematopoiesis, but are not myogenic; muscle “MSCs” are spontaneously myogenic, but do not form bone; cord blood “MSCs” are inherently chondrogenic, and do form bone, but do not support hematopoiesis. However, despite their significant differences, “MSCs” from different sources are capable of forming pericytes when co-transplanted with endothelial cells in vivo, resulting in the development of functional blood vessels. These findings are important not only in understanding the biology of specific tissues, but also from an applicative clinical angle.

Despite antiretroviral therapy, HIV+ individuals still have increased risk to develop lymphomas, including marginal zone lymphomas, suggesting that factors other than HIV-related immunosuppression are probably acting as lymphomagenic factors in the HIV setting. The possible pathogenic involvement of HIV p17 protein variants was investigated in a particularly informative case of HIV-related splenic marginal zone lymphoma, which was negative for oncogenic virus infections, thus allowing us to assess the possible direct contribution of these HIV-encoded proteins to lymphomagenesis. The presence of p17 protein was analyzed by immunohistochemistry in lymphoma tissue. Recombinant p17 protein derived from the dominant sequence detected in plasma and lymphoma biopsy was characterized for B-cell proliferation, clonogenicity in soft agar, in vitro tube formation and wound healing. Intracellular signaling was investigated by immunoblotting. HIV p17 protein was detected in reactive lymphoid follicles but not within lymphoma cells. An identical dominant variant p17 sequence, p17-Lyrm, carrying a 117 to 118 Ala-Ala insertion was detected in both plasma and lymphoma tissue. Recombinant p17-Lyrm enhanced B-cell proliferation and clonogenicity promoted the formation of capillary-like structures and enhanced endothelial cell migration. Unlike reference p17, the p17-Lyrm variant enhanced the activation of Akt and ERK, critical kinases in lymphomagenesis. p17-Lyrm clonogenic activity was dependent on the activation of Akt but not of ERK1/2. These results indicated that HIV p17 variants with distinct molecular signatures and functional properties may accumulate in lymphoid tissues of HIV-infected individuals where they may act as a local stimulus promoting the development of lymphomas.

Summary Several studies have reported endothelial cell (EC) derivation from human induced pluripotent stem cells (hiPSCs). However, few have explored their functional properties in depth with respect to line-to-line and batch-to-batch variability and how they relate to primary ECs. We therefore carried out accurate characterization of hiPSC-derived ECs (hiPSC-ECs) from multiple (non-integrating) hiPSC lines and compared them with primary ECs in various functional assays, which included barrier function using real-time impedance spectroscopy with an integrated assay of electric wound healing, endothelia-leukocyte interaction under physiological flow to mimic inflammation and angiogenic responses in in vitro and in vivo assays. Overall, we found many similarities but also some important differences between hiPSC-derived and primary ECs. Assessment of vasculogenic responses in vivo showed little difference between primary ECs and hiPSC-ECs with regard to functional blood vessel formation, which may be important in future regenerative medicine applications requiring vascularization., Highlights • Side-by-side comparison of hiPSC and primary ECs in standardized assays • Barrier function and inflammatory responses highly consistent among hiPSC-ECs • hiPSC-ECs on differentiation day 10 were similar across independent batches and lines • hiPSC-ECs are more limited in stromal cell requirements than primary ECs, In this article, Orlova and colleagues show that hiPSC-ECs have similar features to primary ECs but also show some differences. hiPSC-ECs exhibited higher barrier function, lower expression of pro-inflammatory adhesive receptors, and more stringent stromal cell requirements. Importantly, healthy control CD31+ hiPSC-ECs showed high consistency between different batches and lines, forming a good basis for disease modeling applications.

Bisphosphonates (BPs) are currently used in the treatment of diverse bone diseases including fibrous dysplasia of bone (FD). In pediatric patients, a radiographic consequence of cyclical administration of BPs is the development of apo-, epi-, and meta-physeal sclerotic bands, otherwise known as zebra lines, which result from the temporary inhibition of osteoclastic activity at the time of drug treatment. We report here on a child with McCune–Albright syndrome (FD in addition to hyperfunctioning endocrinopathies and skin hyperpigmentation) treated with cyclical intravenous infusions of pamidronate in which conventional radiography, contact microradiography, histology, and backscattered electron image analysis demonstrated that zebra lines formed only where bone was normal, were arrested at the boundary between FD-unaffected and FD-affected bone where bone is sclerotic, and were absent within the undermineralized FD bone. Moreover, in spite of the treatment, the FD lesions continued to expand. This case report is unique because no previously published studies correlated the radiographic and the histologic features of BP-induced zebra lines in the metaphysis of an FD-affected long bone of the limbs.

Although infectious complications represent a relevant cause of morbidity and mortality in patients with myelofibrosis (MF), little is known about their incidence, outcome and risk factors. We retrospectively evaluated a cohort of 507 MF patients, diagnosed between 1980 and 2014 in five Italian hematology centers, to define the epidemiology of infections and describe the impact of ruxolitinib (RUX) treatment. Overall, 112 patients (22%) experienced 160 infectious events (grade 3-4, 45%) for an incidence rate of 3.9% per patient-year. Infections were mainly bacterial (78%) and involving the respiratory tract (52% of cases). Also, viral (11%) and fungal infections (2%) were recorded. Overall, infections were fatal in 9% of the cases. Among baseline features, high/intermediate-2 IPSS category (HR 1.8, 95%CI:1.2-2.7; P = 0.02) and spleen length ≥10 cm below left costal margin (HR 1.6, 95%CI:1.1-2.5; P = 0.04) were associated with higher infectious risk in multivariate analysis. Overall, the rate of infections was higher in the cohort of 128 RUX-treated patients (44% vs. 20%, P

Osteonecrosis of the jaw (ONJ) is a well known complication in patients treated with bisphosphonates (BPs) for skeletal metastasis and multiple myeloma (MM). Few oncologic patients under treatment with BPs and with ONJ and metastasis or MM at the same site of the jaw have been described. We report here on a 54-year old white female who was treated with intra-venous zoledronic acid for skeletal metastasis of breast cancer who developed ONJ. Because of a fracture at the site of ONJ, resection of the affected segment was performed. Although metastasis was not suspected by pre-operative image analysis, histological examination revealed syncronous osteonecrosis and breast cancer metastasis in the resected mandibular segment. This case highlights that, in oncologic patients treated with BPs, ONJ may hide malignancy and that histology is the unique tool by which the diagnosis of either osteonecrosis or malignancy or both can be made definitely.

Glial choristoma of the tongue is a rare developmental anomaly usually occurring in the first two years of life. Although diverse theories have been suggested to explain its development, they do not seem to take into account the normal tongue development. We report here on a glial choristoma of the tongue in a two-month-old male with the aim to describe the clinicopathological features of this lesion and to discuss the pathogenetic role of the cells that normally migrate from the cranial neural crests to generate the ectomesenchymal derivatives of the tongue and express neuroglial differentiation as normal developmental pathway.

Background aims: Cord blood (CB) and amniotic fluid (AF) could represent new and attractive mesenchymal stromal cell (MSC) sources, but their potential therapeutic applications are still limited by lack of standardized protocols for isolation and differentiation. In particular, chondrogenic differentiation has never been deeply investigated. Methods: MSCs were obtained from CB and AF samples collected during cesarean sections at term and compared for their biological and differentiation properties, with particular interest in cartilage differentiation, in which quantitative real-time polymerase chain reaction and immunohistochemical analyses were performed to evaluate the expression of type 2 collagen, type 10 collagen, SRY-box9 and aggrecan. Results: We were able to isolate MSCs from 12 of 30 (40%) and 5 of 20 (25%) CB and AF units, respectively. Fluorescence in situ hybridization analysis indicated the fetal origin of isolated MSC strains. Both populations expressed mesenchymal but not endothelial and hematopoietic markers, even though we observed a lower expression of human leukocyte antigen (HLA) I in CB-MSCs. No differences in proliferation rate and cell cycle analysis could be detected. After osteogenic induction, both populations showed matrix mineralization and typical marker expression. Under chondrogenic conditions, pellets derived from CB-MSCs, in contrast with AF-MSCs pellets, were significantly larger, showed cartilage-like morphology and resulted positive for chondrocyte-associated markers, such as type 2 collagen, type 10 collagen, SRY-box9 and aggrecan. Conclusions: Our results show that CB-MSCs and AF-MSCs collected at term differ from each other in their biological and differentiation properties. In particular, only CB-MSCs showed a clear chondrogenic potential and thus could represent an ideal candidate for cartilage-tissue engineering.

An accurate histological diagnosis may distinguish essential thrombocythaemia (ET) from early primary myelofibrosis (early-PMF), which is associated with worse outcome. Outcome of ET is also negatively affected by the presence of the JAK2

Human umbilical cord blood (CB) has attracted much attention as a reservoir for functional hematopoietic stem and progenitor cells, and, recently, as a source of blood-borne fibroblasts (CB-BFs). Previously, we demonstrated that bone marrow stromal cell (BMSC) and CB-BF pellet cultures make cartilage in vitro. Furthermore, upon in vivo transplantation, BMSC pellets remodelled into miniature bone/marrow organoids. Using this in vivo model, we asked whether CB-BF populations that express characteristics of the hematopoietic stem cell (HSC) niche contain precursors that reform the niche. CB ossicles were regularly observed upon transplantation. Compared with BM ossicles, CB ossicles showed a predominance of red marrow over yellow marrow, as demonstrated by histomorphological analyses and the number of hematopoietic cells isolated within ossicles. Marrow cavities from CB and BM ossicles included donor-derived CD146-expressing osteoprogenitors and host-derived mature hematopoietic cells, clonogenic lineage-committed progenitors and HSCs. Furthermore, human CD34+ cells transplanted into ossicle-bearing mice engrafted and maintained human HSCs in the niche. Our data indicate that CB-BFs are able to recapitulate the conditions by which the bone marrow microenvironment is formed and establish complete HSC niches, which are functionally supportive of hematopoietic tissue.

On November 7, 2015, Prof. Paolo Bianco, a trailblazer in the fields of bone and stem cell biology, and a leading advocate for the ethical development and use of cell-based therapies, was abruptly taken away from us. Paolo will be remembered as a man of enormous intellect and incredible curiosity, with an uncanny ability to “connect the dots” in any problem that caught his interest. He was a true gentleman and friend to all who knew him, with a keen wit and sense of humor. His passing is devastating to his family, his colleagues and friends, the scientific community at large, and the public he served.

A rare case of splenic marginal zone lymphoma (SMZL) in a human immunodeficiency virus (HIV)-1 infected patient is described. As an association between SMZL and viral infections has been reported, the presence of the hepatitis C virus and HIV-1 genomes was evaluated. Only HIV-1 DNA levels were detected in enriched splenic B lymphocytes, suggesting a HIV-1 involvement in lymphomagenesis.

Aim Sinus augmentation procedures commonly employ osteoconductive scaffolding materials to stimulate and support bone formation. The aim of this study was to develop a simple screening methodology for the evaluation of the osteoconductive potential of various bone graft materials prior to clinical use. Materials and methods Materials tested were Bio-Oss, Bi-Ostetic, OraGraft, and ProOsteon. These Simple and composite bone substitutes were embedded with osteoprogenitor cells derived from either the human maxillary sinus schneiderian membrane (hMSSM) or from maxillary tuberosity bone marrow and then monitored both in vitro and in vivo. Results Cell adherence and proliferation was most pronounced in OraGraft, followed by ProOsteon. In vivo bone formation, within the bone graft, was also observed, with most marked results in OraGraft and ProOsteon grafts. Conclusions The proposed osteoconductivity testing method proved simple, informative, and reliable for the purpose of screening candidate biomaterials for sinus lifting or sinus augmentation.

Maxillary sinus membrane lifting is a common procedure aimed at increasing the volume of the maxillary sinus osseous floor prior to inserting dental implants. Clinical observations of bone formation in sinus lifting procedures without grafting bone substitutes were observed, but the biological nature of bone regeneration in sinus lifting procedures is unclear. This study tested whether this osteogenic activity relies on inherent osteogenic capacity residing in the sinus membrane by simulating the in vivo clinical condition of sinus lifting in an animal model. Maxillary sinus membrane cells were cultured in alpha-MEM medium containing osteogenic supplements (ascorbic acid, dexamethasone). Cultured cells revealed alkaline phosphatase activity and mRNA expression of osteogenic markers (alkaline phosphatase, bone sialoprotein, osteocalcin and osteonectin) verifying the osteogenic potential of the cells. Fresh tissue samples demonstrated positive alkaline phosphatase enzyme activity situated along the membrane-bone interface periosteum-like layer. To simulate the in vivo clinical conditions, the membranes were folded to form a pocket-like structure and were transplanted subcutaneously in immunodeficient mice for 8 weeks. New bone formation was observed in the transplants indicating the innate osteogenic potential within the maxillary Schneiderian sinus membrane and its possible contribution to bone regeneration in sinus lifting procedures.

Human skeletal progenitors were engineered to stably express R201C mutated, constitutively active Gs alpha using lentiviral vectors. Long-term transduced skeletal progenitors were characterized by an enhanced production of cAMP, indicating the transfer of the fundamental cellular phenotype caused by activating mutations of Gs alpha. Like skeletal progenitors isolated from natural fibrous dysplasia (FD) lesions, transduced cells could generate bone but not adipocytes or the hematopoietic microenvironment on in vivo transplantation. In vitro osteogenic differentiation was noted for the lack of mineral deposition, a blunted upregulation of osteocalcin, and enhanced upregulation of other osteogenic markers such as alkaline phosphatase (ALP) and bone sialoprotein (BSP) compared with controls. A very potent upregulation of RANKL expression was observed, which correlates with the pronounced osteoclastogenesis observed in FD lesions in vivo. Stable transduction resulted in a marked upregulation of selected phosphodiesterase (PDE) isoform mRNAs and a prominent increase in total PDE activity. This predicts an adaptive response in skeletal progenitors transduced with constitutively active, mutated Gs alpha. Indeed, like measurable cAMP levels, the differentiative responses of transduced skeletal progenitors were profoundly affected by inhibition of PDEs or lack thereof. Finally, using lentiviral vectors encoding short hairpin (sh) RNA interfering sequences, we demonstrated that selective silencing of the mutated allele is both feasible and effective in reverting the aberrant cAMP production brought about by the constitutively active Gs alpha and some of its effects on in vitro differentiation of skeletal progenitors.

Few studies focused on the prevalence of scoliosis and involvement of the spine in patients with fibrous dysplasia (FD) of bone. We examined for FD involvement of the spine and scoliosis in 56 patients affected by FD of bone. Fifty patients were part of a cohort reported in a multicentric study on FD promoted by European Pediatric Orthopedic Society (EPOS) in 1999, and six were new patients. There were 30 females and 26 males (mean age 12.5 years; range 1–42 years). Twenty-three had monostotic FD, 9 polyostotic FD, and 24 McCune-Albright Syndrome (MAS). Scoliosis was observed in 11 cases of polyostotic FD and MAS (33.3%). In seven of the patients with scoliosis (63.3%) spine was involved by FD lesional tissue. FD lesions involved the thoracic or lumbar spine in all patients but one, where cervical spine was also affected. A correlation between scoliosis and either spinal (p

We studied the role of somatic mosaicism in fibrous dysplasia of bone (FD) within the context of skeletal ("mesenchymal") stem cells by assessing the frequency of mutated colony forming unit-fibroblasts (CFU-Fs) from FD lesions, and in some cases, from unaffected sites, in a series of patients. There was a tight inverse correlation between the percentage mutant CFU-F versus age, suggesting demise of mutant stem cells caused by exuberant apoptosis noted in samples from young patients. In older patients, either partially or completely normal bone/marrow histology was observed. On in vivo transplantation, FD ossicles were generated only by cell strains in which mutant CFU-Fs were identified. Strains that lacked mutant CFU-F (but were mutation positive) failed to regenerate an FD ossicle. These data indicate that GNAS mutations are only pathogenic when in clonogenic skeletal stem cells. From these data, we have evolved the novel concept of "normalization" of FD. As a lesion ages, mutant stem cells fail to self-renew, and their progeny are consumed by apoptosis, whereas residual normal stem cells survive, self-renew, and enable formation of a normal structure. This suggests that activating GNAS mutations disrupt a pathway that is required for skeletal stem cell self-renewal.

SummaryThe identity of cells that establish the hematopoietic microenvironment (HME) in human bone marrow (BM), and of clonogenic skeletal progenitors found in BM stroma, has long remained elusive. We show that MCAM/CD146-expressing, subendothelial cells in human BM stroma are capable of transferring, upon transplantation, the HME to heterotopic sites, coincident with the establishment of identical subendothelial cells within a miniature bone organ. Establishment of subendothelial stromal cells in developing heterotopic BM in vivo occurs via specific, dynamic interactions with developing sinusoids. Subendothelial stromal cells residing on the sinusoidal wall are major producers of Angiopoietin-1 (a pivotal molecule of the HSC “niche” involved in vascular remodeling). Our data reveal the functional relationships between establishment of the HME in vivo, establishment of skeletal progenitors in BM sinusoids, and angiogenesis.

Both FGF-23 and PTH inhibit renal phosphate reabsorption. We treated two patients with TIO and FGF-23–mediated hypophosphatemia with cinacalcet to test the hypothesis that medicinally induced hypoparathyroidism would decrease renal phosphate wasting. Cinacalcet treatment resulted in increased renal phosphate reabsorption, allowed for a decrease in phosphate supplementation, and showed evidence of bone healing in one of the two patients. Introduction: Tumor-induced osteomalacia (TIO) is a rare, acquired disease of renal phosphate wasting, which results in hypophosphatemia and osteomalacia. It is caused by mesenchymal tumors that produce the phosphate and vitamin D–regulating hormone, fibroblast growth factor (FGF)-23. Removal of the tumor is curative, but the tumors are often difficult to locate. Medical treatment involves high doses of oral phosphate and calcitriol, but the phosphate is often poorly tolerated and leads to diarrhea. Because PTH also promotes phosphaturia, and patients with hypoparathyroidism are hyperphosphatemic in the setting of elevated serum FGF-23, we postulated that the calcium-sensing receptor agonist, cinacalcet, which can induce hypoparathyroidism, would be an effective adjuvant in the treatment of TIO. Materials and Methods: Two subjects with presumed TIO in whom the tumor was not located after extensive testing and who did not tolerate medical therapy with phosphorus and calcitriol were treated with cinacalcet. Results: Neither treatment with phosphorus nor combined treatment with phosphorus and calcitriol had an effect on serum FGF-23 levels. Treatment with cinacalcet resulted in increased renal phosphate reabsorption and serum phosphorus and allowed for a decrease in phosphate supplementation to a dose that was tolerated. On this regimen, one patient showed significant bone healing as shown by resolution of activity on bone scan and lack of osteomalacia as assessed by histomorphometry. Conclusions: These data show that medically induced hypoparathyroidism with cinacalcet is a therapeutic option for disorders of FGF-23–mediated hypophosphatemia and that, in the absence of PTH, the phosphaturic effect of FGF-23 is decreased.

In order to evaluate the predictive value of positron emission tomography-computed tomography (PET/CT) in discriminating the presence of a Richter's syndrome (RS) or a second malignancy (SM), as well as to evaluate its prognostic value in patients with chronic lymphocytic leukemia (CLL), we retrospectively analyzed the data of 90 patients who, in the suspicion of a RS or a SM, underwent PET/CT followed by the biopsy of the involved tissue. The median maximum Standardized Uptake Value (SUV max) in the presence of a CLL/small lymphocytic lymphoma, a diffuse large B-cell lymphoma (DLBCL), a Hodgkin lymphoma (HL), a SM were 3.5, 14.6, 7.0 and 6.3, respectively (P ⩽ 0.0001). A SUV max cutoff value ⩾ 5 showed a sensitivity, specificity, positive and negative predictive values of 88.2, 71.2, 51.3 and 94%, respectively, for the presence of a more aggressive disease (DLBCL, HL and SM). A SUV max ⩾ 5 identified also a subset of treatment naive patients with an inferior progression-free survival (P = 0.011) and overall survival (P = 0.067). These findings suggest that PET/CT may helpfully integrate the biologically-based prognostic stratification of CLL. Prospective clinical trials including larger cohorts of patients are needed to conclusively define the role and prognostic impact of PET/CT in the routine management of CLL patients.

Neonatal bone marrow transplantation (nBMT) could offer a novel therapeutic opportunity for genetic disorders by providing sustainable levels of the missing protein at birth, thus preventing tissue damage. We tested this concept in Mucopolysaccharidosis type I (MPS IH, Hurler syndrome), a lysosomal storage disorder caused by deficiency of α-L-iduronidase (IDUA). MPS IH is characterized by a broad spectrum of clinical manifestations including severe progressive skeletal abnormalities. Although BMT increases the life span of MPS IH patients, musculoskeletal manifestations are only minimally responsive if the timing of BMT delays, suggesting already irreversible bone damage. In this study, we tested the hypothesis that transplanting normal bone marrow into newborn MPS I mice, soon after birth, can prevent skeletal dysplasia. 1- to 2-day-old mutant mice were conditioned using a single administration of 20 mg/kg busulfan and then injected via the superficial temporal vein with 2 x 106 bone marrow cells from wild type (WT) donors. Age-matched WT and untreated MPS I mice were used as controls. Transplantation of normal bone marrow cells into preconditioned MPS I and WT neonates led to a similar engraftment level at 37 weeks after nBMT (peripheral blood, median MPS I nBMT 81.30%, range from 0.80% to 95.80% vs. median WT nBMT 67.45%, range from 16.00% to 95.86%, p = 0.714). Spleen, PB and thymus cells of nBMT MPS I mice were repopulated with committed lymphoid and myeloid populations similar to the transplanted WT mice. The >50% replacement of the hematopoiesis resulted in a measurable increase in IDUA activity in visceral organs, especially in the spleen, showing a correlation between engraftment levels and enzyme activity with clearance of GAGs from blood and tissues. At the time of euthanasia (37-week-old), reconstitution of normal hematopoiesis in MPS I mice was associated with a consistent amelioration of bone pathology, as revealed by radiographic skeletal examination. Radiographic analysis has shown that the width of the humerus, radius/ulna, femur and tibia of untreated MPS I mice was significantly larger at comparison with WT littermates. For MPS I nBMT mice, long bone widths, including the humerus (p = 0.0014, vs. untreated MPS I mice), the radius/ulna (p = 0.0003, vs. untreated MPS I mice), the femur (p = 0.0003, vs. untreated MPS I mice), and the tibia (p = 0.0003, vs. untreated MPS I mice) significantly decreased, compared to untreated MPS I mice. Furthermore, several three-dimensional architectural parameters in femurs such as trabecular number and separation, cortical thickness and bone mineral volume were analyzed by micro-CT, resulting in a significant difference between untreated and nBMT MPS I mice. All examined nBMT MPS I mice displayed bone parameter values comparable to WT mice, confirming that nBMT mice had significant improvements in skeletal phenotype approaching complete normalization of each parameter tested. Histologically, in MPS I cortical bone, osteocytes were increased and contained vacuoles, likely reflecting GAGs storage. Histological amelioration of these features was consistently observed in femurs of all nBMT mice with a definite reduction in both hyperosteocytosis and lysosomal vacuolization, confirming that the perinatal treatment of the disease can positively impact the skeletal phenotype in MPS I. We also evaluated KS levels in the blood as a biomarker of MPS with skeletal dysplasia. Normalization of blood KS level strongly supports the notion that nBMT corrects the pathological and clinical bone lesions in nBMT MPS I mice. Our findings demonstrate that nBMT prevents some of the relevant abnormalities of the skeletal pathology in the MPS I mouse model. Moreover, improvements in bone parameters correlated with high levels of bone marrow-derived cell engraftment in multiple hematopoietic compartments, suggesting that the early and complete restoration of normal hematopoiesis can have significant impact on the bone development of newborn MPS I mice. Future clinical trials are needed to confirm our findings. Disclosures No relevant conflicts of interest to declare.

Systems for gene transfer and silencing in human skeletal stem cells (hSSCs, also stromal or mesenchymal stem cells) are important for addressing critical issues in basic hSSC and skeletal biology and for developing gene therapy strategies for treatment of skeletal diseases. Whereas recent studies have shown the efficacy of lentiviral transduction for gene transfer in hSSCs in vitro, no study has yet proven that lentivector-transduced hSSCs retain their distinctive organogenic potential in vivo, as probed by in vivo transplantation assays. Therefore, in addition to analyzing the in vitro growth and differentiation properties of hSSCs transduced with advanced-generation lentivectors, we ectopically transplanted LV-eGFP-transduced hSSCs (along with an osteoconductive carrier) in the subcutaneous tissue of immunocompromised mice. eGFP-transduced cells formed heterotopic ossicles, generating osteoblasts, osteocytes, and stromal cells in vivo, which still expressed GFP at 2 months after transplantation. eGFP-expressing cells could be recovered from the ossicles 8 weeks posttransplantation and reestablished in culture as viable and proliferating cells. Further, we investigated the possibility of silencing individual genes in hSSCs using lentivectors encoding short hairpin precursors of RNA interfering sequences under the control of the Pol-III-dependent H1 promoter. Significant long-term silencing of both lamin A/C and GFP (an endogenous gene and a transgene, respectively) was obtained with lentivectors encoding shRNAs. These data provide the basis for analysis of the effect of gene knockdown during the organogenesis of bone in the in vivo transplantation system and for further studies on the silencing of alleles carrying dominant, disease-causing mutations.

FGF-23, a novel member of the FGF family, is the product of the gene mutated in autosomal dominant hypophosphatemic rickets (ADHR). FGF-23 has been proposed as a circulating factor causing renal phosphate wasting not only in ADHR (as a result of inadequate degradation), but also in tumor-induced osteomalacia (as a result of excess synthesis by tumor cells). Renal phosphate wasting occurs in approximately 50% of patients with McCune-Albright syndrome (MAS) and fibrous dysplasia of bone (FD), which result from postzygotic mutations of the GNAS1 gene. We found that FGF-23 is produced by normal and FD osteoprogenitors and bone-forming cells in vivo and in vitro. In situ hybridization analysis of FGF-23 mRNA expression identified "fibrous" cells, osteogenic cells, and cells associated with microvascular walls as specific cellular sources of FGF-23 in FD. Serum levels of FGF-23 were increased in FD/MAS patients compared with normal age-matched controls and significantly higher in FD/MAS patients with renal phosphate wasting compared with those without, and correlated with disease burden bone turnover markers commonly used to assess disease activity. Production of FGF-23 by FD tissue may play an important role in the renal phosphate-wasting syndrome associated with FD/MAS.

Objective Fibrous dysplasia (FD) is a skeletal disorder often associated with McCune-Albright syndrome, a rare multisystem disorder caused by GNAS1 gene mutation. FD frequently affects the craniofacial bones, including the maxilla and the mandible; nevertheless, its effects on dental tissues and the implications for dental care remain unclear. The aim of this study was to characterize the dental features associated with FD and the reaction of affected bones to routine dental therapy. Study design Thirty-two patients with FD underwent dental evaluation and endocrine testing as part of the diagnosis of FD/McCune-Albright syndrome. Any dental anomalies were recorded, and the associations between endocrinopathies and dental anomalies were analyzed statistically by means of the paired t test. Results Eighty-four percent had FD in the maxilla and/or mandible; endocrine dysfunction; and/or renal phosphate wasting. The caries index scores were 2.9 (ages 4-17 years) and 9.6 (ages 18-50 years). Malocclusion (81%) and other prevalent dental anomalies (41%) included tooth rotation, oligodontia, and taurodontism. The expansion of the maxilla or mandible by FD did not distort the dental arch curvature, and routine dental therapies such as extractions, restorations, and orthodontic treatment did not exacerbate FD lesions. Conclusion Maxillomandibular FD was associated with higher rates of caries and malocclusion than were present in healthy patients. Furthermore, patients with FD did not require special dental management and were able to undergo routine dental care without an exacerbation of FD lesions.

Deposition, mineralization, and resorption of FD bone compared with unaffected bone from FD patients was investigated in iliac crest biopsy specimens from 13 patients. Compared with unaffected bone, lesional FD bone seemed to be very sensitive to the effects of PTH and renal phosphate wasting, which respectively bring about hyperparathyroid or osteomalacic changes in the lesional bone.Introduction: Fibrous dysplasia is a genetic noninherited disease caused by activating mutations of the GNAS1 gene, resulting in the deposition of qualitatively abnormal bone and marrow. This study was designed to learn more about the local processes of bone deposition, mineralization, and resorption within lesional fibrous dysplasia (FD) bone compared with unaffected bone of FD patients.Methods: Histology, histomorphometry, and quantitative back-scattered electron imaging (qBSE) analysis was conducted on affected and unaffected biopsy specimens from 13 patients and correlated to markers of bone metabolism.Results and Conclusions: There was a marked excess of unmineralized osteoid with a nonlamellar structure and a reduced mineral content in mineralized bone within FD lesions (p < 0.001). A negative correlation (p = 0.05) between osteoid thickness (O.Th) and renal tubular phosphate reabsorption (measured as TmP/GFR) was observed for lesional bone, but not for unaffected bone, in which no histological or histomorphometric evidence of osteomalacia was observed in patients with renal phosphate wasting. Histological and histomorphometric evidence of increased bone resorption was variable in lesional bone and correlated with serum levels of parathyroid hormone (PTH). Hyperparathyroidism-related histological changes were observed in fibrous dysplastic bone, but not in the unaffected bone, of patients with elevated serum PTH secondary to vitamin D deficiency. Our data indicate that, compared with unaffected bone, lesional FD bone is very sensitive to the effects of PTH and renal phosphate wasting, which, respectively, bring about hyperparathyroid or osteomalacic changes in the lesional bone. Osteomalacic and hyperparathyroid changes, which emanate from distinct metabolic derangements (which superimpose on the local effects of GNAS1 mutations in bone), influence, in turn, the severity and type of skeletal morbidity in FD.

International audience; Fibrous dysplasia of bone (FD) is a crippling skeletal disease associated with postzygotic mutations (R201C, R201H) of the gene encoding the α subunit of the stimulatory G protein, Gs. By causing a characteristic structural subversion of bone and bone marrow, the disease results in deformity, hypomineralization, and fracture of the affected bones, with severe morbidity arising in childhood or adolescence. Lack of inheritance of the disease in humans is thought to reflect embryonic lethality of germline-transmitted activating Gsα mutations, which would only survive through somatic mosaicism. We have generated multiple lines of mice that express Gsα(R201C) constitutively and develop an inherited, histopathologically exact replica of human FD. Robust transgene expression in neonatal and embryonic tissues and embryonic stem (ES) cells were associated with normal development of skeletal tissues and differentiation of skeletal cells. As in humans, FD lesions in mice developed only in the postnatal life; a defined spatial and temporal pattern characterized the onset and progression of lesions across the skeleton. In individual bones, lesions developed through a sequence of three distinct histopathological stages: a primary modeling phase defined by endosteal/medullary excess bone formation and normal resorption; a secondary phase, with excess, inappropriate remodeling; and a tertiary fibrous dysplastic phase, which reproduced a full-blown replica of the human bone pathology in mice of age ≥1 year. Gsα mutations are sufficient to cause FD, and are per se compatible with germline transmission and normal embryonic development in mice. Our novel murine lines constitute the first model of FD. © 2014 American Society for Bone and Mineral Research.

Context: Fibrous dysplasia (FD) is a rare skeletal disorder, resulting in deformity, fracture, functional impairment, and pain. Bisphosphonates have been advocated as a potential treatment. Objective: To determine the efficacy of alendronate for treatment of FD. Design: Two-year randomized, double-blind, placebo-controlled trial. Setting: Clinical research center. Patients: Forty subjects with polyostotic FD (24 adults, 16 children). Subjects were randomized and stratified by age. Interventions: Study drug was administered over a 24 month period in 6 month cycles (6 months on, 6 months off). Alendronate dosing was stratified: 40 mg daily for subjects >50 kg, 20 mg for 30–50 kg, 10 mg for 20–30 kg. Main Outcome Measures: Primary endpoints were bone turnover markers, including serum osteocalcin, and urinary NTX-telopeptides. Secondary endpoints included areal bone mineral density (aBMD), pain, skeletal disease burden score, and functional parameters including the 9-min walk test and manual muscle testing. Results: Clinical data was collected on 35 subjects who completed the study. There was a decline in NTX-telopeptides in the alendronate group (P = .006), but no significant difference in osteocalcin between groups. The alendronate group had an increase in areal BMD in normal bone at the lumbar spine (P = .006), and in predetermined regions of FD (P < .001). There were no significant differences in pain scores, skeletal disease burden scores, or functional parameters between the groups. Conclusions: Alendronate treatment led to a reduction in the bone resorption marker NTX-telopeptides, and improvement in aBMD, but no significant effect on serum osteocalcin, pain, or functional parameters.