Cardiac myxoma cells exhibit embryonic endocardial stem cell features

The origin of myxoma, the most frequent tumour of the heart, remains uncertain. Previous phenotypic characterizations have shown heterogeneous results and the most recent hypothesis suggests that cardiac myxoma originates from a primitive pluripotential cardiogenic cell. We investigated the expression of actin isoforms in 30 left atrial myxomas by immunohistochemistry and in eight consecutive tumours by RT-PCR. alpha-Smooth muscle actin (alpha-SMA) protein and/or transcripts were detected in all cases, whereas alpha-cardiac actin was observed in few cases and alpha-skeletal actin was always absent. Besides classical features, vessel-like structures were characterized by cells expressing CD34 and, less frequently, alpha-SMA. Confocal microscopy showed focal co-expression of CD34 and alpha-SMA in myxoma cells, suggesting a gradual loss of stem endothelial markers and the acquisition of myocytic antigens. In order to confirm this hypothesis, early cardiac differentiation markers were also investigated. RT-PCR documented the presence of transcripts for Sox9 (100%), Notch1 (87.5%), NFATc1 (37.5%), Smad6, metalloproteinases 1 and 2 alone or in variable combinations and the absence of ErbB3 and WT1. Myxoma cells maintained phenotypic heterogeneity in vitro, including the expression of alpha-SMA and the presence of stress fibres. These findings document in cardiac myxoma cells phenotypic markers of the embryonic endothelial-to-mesenchymal transformation that precedes terminal differentiation of endocardial cushions, supporting the hypothesis that cardiac myxoma cells may derive from adult developmental remnants.

[Cardiac tumors]

Primary cardiac tumors are rare and their subdivision often difficult because of their unknown origin. In the most recent classification, cardiac tumors are divided into benign (about 75% and malignant neoplasms in relationship to their tissue differentiation (rhabdomyoma, haemangioma, etc.) or uncertain aetiology (myxoma, papillary fibroelastoma). Primary malignant tumors are maimly represented by sarcomas. The most frequent tumor is cardiac myxoma, which by itself represents about 50% of all primary cardiac neoplasms. Although non-invasive technologies as trans-esophageal ecocardiography allow the detection and exact localization of cardiac mass, clinical diagnosis is often tardive. This is due, besides the intrinsic rarity, to two main factors: first, the tumor is often asymptomatic (incidental autopic finding) or; alternatively, it may show aspecif symptoms mimicking heart failure or other pathologies. In this article, clinicopathological features of main primary cardiac tumors are presented. Investigation of the histogenesis of some of these neoplasms is still a primary field of research.

Electrophysiological properties of mouse bone marrow c-kit cells co-cultured onto neonatal cardiac myocytes

OBJECTIVE

Controversy about hematopoietic stem cells reprogramming into cardiac myocytes is currently supported by positive and negative findings. In fact, some reports have shown the ability of stem cells from the bone marrow (BM) to differentiate into cardiac myocytes and to contribute to myocardium repair, while others have reported the opposite.

METHODS

C-kit(+) cells from mouse bone marrow were co-cultured onto neonatal cardiac myocytes. Hematopoietic stem cell-derived cells were analyzed by investigating the expression of cardiac markers and ion channels and by single-cell electrophysiological recordings.

RESULTS

Groups of undifferentiated c-kit(+) cells displayed only outward currents. Co-cultured c-kit(+) stem cells on neonatal cardiac myocytes expressed cardiac markers and Na(+) and Ca(2+) voltage-gated ion channels. However, Na(+) and Ca(2+) currents were not detected by electrophysiological patch-clamp recordings even if caffeine and cyclopiazonic acid treatment showed the presence of intracellular calcium stores. This suggests that these channels, although expressed, were not functional and thus do not allow the coupling between excitation and contraction that is typical of cardiac myocytes. Nevertheless, co-cultured cells had a more hyperpolarized resting membrane potential and, at least in a subset of cells, displayed voltage-gated inward rectifier currents and outward currents. Co-cultured c-kit(+)-derived cells were not connected to surrounding cardiac myocytes through gap junctions. To induce a more pronounced differentiation, co-cultured cells were treated with BMP-4 and TGF-beta, two factors that were shown to trigger a cardiac myocyte differentiation pathway in embryonic stem (ES) cells. Even under these conditions, c-kit(+) cells did not differentiate into functionally active cardiac myocytes. However, TGF-beta/BMP-4-treated cells were hyperpolarized and showed and increased inward rectifier current density.

CONCLUSIONS

Our study shows that mouse BM hematopoietic stem cells exhibit a limited plasticity to transdifferentiate into cardiac myocytes in culture.

Repeated fine-needle aspiration of the thyroid in benign nodular thyroid disease: critical evaluation of long-term follow-up

Fine-needle aspiration (FNA) is the most effective diagnostic means in the management of nodular thyroid disease. Therefore, we decided to evaluate the diagnostic reproducibility of FNA and the usefulness of repeated FNA in benign nodular thyroid disease. We evaluated 799 satisfactory aspirations performed in 306 patients (298 females) aged 14-84 years, followed for 2-12 years. FNAs were performed on an annual basis. Of all patients, 299 (97.71%) maintained benignity: 230 (75.16%) repeated the same cytologic pattern, and 69 (22.54%) showed diagnostic variations within benign pathologies. In 3 patients (0.98%) the diagnosis changed to suspicious and in 4 (1.30%) to papillary carcinoma in the whole group. Of these 4 cases, 1 was diagnosed in the second (0.57%) and 3 in the third repeat FNA (2.25%). In 6 cases in which increased nodular size was observed, no change to malignancy was detected, while 3 of the carcinomas found showed no changes in size.

IN CONCLUSION

(1) The variation in cytologic diagnoses within benign pathologies can be attributed to the coexistence of nonuniform pathologies. Aspirations performed in different sites of the nodule would contribute to obtain a more representative specimen. (2) In the absence of suspicious clinical changes and with at least three FNAs confirming the cytologic diagnosis of benignity, the follow-up of nodules by FNA could be discontinued and (3) In our experience, the diagnostic change from benign to malignant after three repeat FNAs appears to indicate that it would be advisable to perform three procedures.

Unusual cardiac tumour with perivascular myoid differentiation: a case report

A previously healthy 70 year old woman was admitted for fatigue and dyspnoea on exertion and cough. A two dimensional echocardiography revealed a mass in the right atrium, which obstructed filling and infiltrated the cardiac chamber wall. Postsurgical histological examination revealed an unusual tumour with prevalent myoid glomangiopericytoma-type and haemangiopericytoma-like patterns. Mitosis and necrosis were absent. A computed tomography scan excluded the presence of metastasis to distant organs or, conversely, metastatic involvement of the heart. Therefore, a diagnosis of tumour with perivascular myoid differentiation was made. This new entity, recently described in soft tissues, can easily recur. Its recognition helps to differentiate from metastasis and other primitive cardiac tumours sharing some morphological features but a different clinical behaviour, with consequent improvement to the management of patient care.

Cellular retinol-binding protein-1 expression in endometrial stromal cells: physiopathological and diagnostic implications

AIMS

Cellular retinol-binding protein-1 (CRBP-1) contributes to the maintenance of the differentiated state of the endometrium through retinol bioavailability regulation. The aim was to analyse CRBP-1 expression in endometrial stromal cells at eutopic and ectopic sites in different physiopathological conditions.

METHODS AND RESULTS

Antibodies to CRBP-1, CD10 and alpha-smooth muscle actin were applied to proliferative (n = 10), secretory (n = 9) and atrophic (n = 7) endometrium, decidua (n = 4), adenomyosis (n = 5), endometriosis (n = 10), endometrial polyps (n = 9), simple endometrial hyperplasia (n = 6), well-differentiated endometrioid carcinoma (n = 6) and submucosal leiomyomas (n = 5). In some cases, Western blotting and reverse transcription-polymerase chain reaction were also applied. CRBP-1 was expressed by eutopic and ectopic endometrial stromal cells more markedly during the late secretory phase and in decidua of pregnancy. CRBP-1 expression was low in the stroma of atrophic endometrium and absent in myometrium, leiomyomas and cervical stroma. CD10 immunoreactivity was weak in atrophic endometrium and in decidua.

CONCLUSIONS

CRBP-1 expression characterizes endometrial stromal cells at eutopic and ectopic sites and appears to be more specific than CD10. The level of CRBP-1 varies in intensity according to hormonal variations, reaching its maximum in predecidua and decidua. Thus, immunodetection of CRBP-1 may help to elucidate the physiopathological changes which occur in endometrial stroma and can also be applied as an adjuvant stromal marker.

Microscopic approach to critical phenomena at interfaces: an application to complete wetting in the Ising model

We study how the formalism of the hierarchical reference theory (HRT) can be extended to inhomogeneous systems. HRT is a liquid-state theory which implements the basic ideas of the Wilson momentum-shell renormalization group (RG) to microscopic Hamiltonians. In the case of homogeneous systems, HRT provides accurate results even in the critical region, where it reproduces scaling and nonclassical critical exponents. We applied the HRT to study wetting critical phenomena in a planar geometry. Our formalism avoids the explicit definition of effective surface Hamiltonians but leads, close to the wetting transition, to the same renormalization group equation already studied by RG techiques. However, HRT also provides information on the nonuniversal quantities because it does not require any preliminary coarse graining procedure. A simple approximation to the infinite HRT set of equations is discussed. The HRT evolution equation for the surface free energy is numerically integrated in a semi-infinite three-dimensional Ising model and the complete wetting phase transition is analyzed. A renormalization of the adsorption critical amplitude and of the wetting parameter is observed. Our results are compared to available Monte Carlo simulations.

Hydration, stability, and phase transformations of a new antitumor drug

We studied hydration equilibria and phase transformations in a cytotoxic drug (BBR3576). The original sample is a hydrated compound that undergoes a structural phase transition when it looses about half of its structural water. Such a structural transition is completely reversible: the partially dehydrated form is stable up to 130 degrees C (or up to 140 degrees C for several minutes) and reverts to the original form upon rehydration. Completely different phase relationships are observed if an original sample is fully dehydrated: when all water has been released, a metastable anhydrous phase forms, which undergoes an irreversible exothermic conversion to a stable phase. Upon rehydration at room temperature of such an anhydrous phase, a new hydrated form is obtained, which is definitely different from the original one.

SDF-1 involvement in endothelial phenotype and ischemia-induced recruitment of bone marrow progenitor cells

Chemokine stromal derived factor 1 (SDF-1) is involved in trafficking of hematopoietic stem cells (HSCs) from the bone marrow (BM) to peripheral blood (PB) and has been found to enhance postischemia angiogenesis. This study was aimed at investigating whether SDF-1 plays a role in differentiation of BM-derived c-kit(+) stem cells into endothelial progenitor cells (EPCs) and in ischemia-induced trafficking of stem cells from PB to ischemic tissues. We found that SDF-1 enhanced EPC number by promoting alpha(2), alpha(4), and alpha(5) integrin-mediated adhesion to fibronectin and collagen I. EPC differentiation was reduced in mitogen-stimulated c-kit(+) cells, while cytokine withdrawal or the overexpression of the cyclin-dependent kinase (CDK) inhibitor p16(INK4) restored such differentiation, suggesting a link between control of cell cycle and EPC differentiation. We also analyzed the time course of SDF-1 expression in a mouse model of hind-limb ischemia. Shortly after femoral artery dissection, plasma SDF-1 levels were up-regulated, while SDF-1 expression in the bone marrow was down-regulated in a timely fashion with the increase in the percentage of PB progenitor cells. An increase in ischemic tissue expression of SDF-1 at RNA and protein level was also observed. Finally, using an in vivo assay such as injection of matrigel plugs, we found that SDF-1 improves formation of tubulelike structures by coinjected c-kit(+) cells. Our findings unravel a function for SDF-1 in increase of EPC number and formation of vascular structures by bone marrow progenitor cells.

Topical treatment of basal cell carcinoma with tazarotene: a clinicopathological study on a large series of cases

BACKGROUND

Basal cell carcinoma (BCC) is the most common cancer in humans. Medical treatment modalities offer cost reductions and clinical advantages in selected cases such as low-risk areas, surgically inaccessible sites, patients with multiple neoplasms, and older, infirm or anticoagulated subjects. Tazarotene has been proposed for the treatment of BCC; however, data on its efficacy are lacking.

OBJECTIVES

To investigate the efficacy of tazarotene in a large series of BCCs, better to define the clinical advantages and the mechanisms of action in vivo.

METHODS

Tazarotene 0.1% gel was applied daily for 24 weeks to 154 small superficial and nodular BBCs. Clinicopathological changes were followed during the therapy by dermoscopic and histological examination. Proliferation, retinoic acid receptors and apoptosis were investigated by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labelling on biopsies.

RESULTS

At 24 weeks of therapy, 70.8% of the BCCs showed > 50% clinical and dermoscopic regression, and 30.5% healed without recurrences after 3 years of follow-up. At 12 weeks, biopsies showed that regression was associated with reduced proliferation and increased apoptosis of basaliomatous cells. Most unresponsive tumours displayed a keratotic differentiation.

CONCLUSIONS

Tazarotene was effective in the majority of superficial and nodular undifferentiated BCCs treated, possibly by antiproliferative and proapoptotic actions in vivo. Keratotic BCCs were the major type among the unresponsive tumours, and were characterized by overexpression of p53 and cellular retinol binding protein-1 in comparison with undifferentiated tumours. Topical tazarotene represents an alternative medical choice for selected cases of BCC.

The recombinant major allergen of Parietaria judaica and its hypoallergenic variant: in vivo evaluation in a murine model of allergic sensitization

BACKGROUND

Par j 1 represents the major allergenic component of Parietaria judaica pollen. Its three-dimensional structure is stabilized by four disulphide bridges. A family of three-dimensional mutants of the recombinant Par j 1 (rPar j 1) allergen, showing reduced allergenicity and retained T cell recognition has been recently developed by site-directed mutagenesis.

OBJECTIVE

To develop and characterize a murine model of IgE sensitization to rPar j 1. To evaluate similarities between the murine model and the human IgE response. To investigate in this model the recognition of a hypoallergenic mutant of Par j 1, and to study the immune responses elicited in mice by the mutant itself.

METHODS

BALB/c mice were sensitized by two intraperitoneal immunizations with rPar j 1 in alum on days 0 and 21. Allergen-specific serum IgE and IgG responses were studied by direct ELISA and immunoblotting, ELISA inhibition and competitive ELISA. Cell proliferation was evaluated in splenocyte cultures.

RESULTS

Sensitization with rPar j 1 induced high levels of IgE and IgG1 vs. low levels of IgG2a. Mouse antibodies specific to rPar j 1 were able to compete with human IgE for recognition of rPar j 1. IgE from mice immunized with rPar j 1 showed a significantly reduced binding activity towards the hypoallergenic variant rPjC, which lacks three disulphide bridges. On the contrary, rPjC was recognized by IgG1 and IgG2a antibodies as well as rPar j 1. The proliferative response to rPjC by splenocytes from mice immunized with rPar j 1 was comparable to that stimulated by rPar j 1. Immunization with rPjC induced low levels of IgE antibodies to the rPjC itself, while IgG and proliferative responses were similar to those induced by rPar j 1.

CONCLUSION

Conformational variants of allergens, displaying reduced allergenicity accompanied by retained IgG and T cell recognition, offer a safe, specific and flexible approach to immunotherapy of type I allergy. Our mouse model of IgE sensitization to a recombinant allergen, mimicking the human response to its native counterpart, could provide valuable information for pre-clinical testing of such hypoallergenic molecules.

Symptomatic laryngeal nodular chondrometaplasia: a clinicopathological study

A 41 year old man with a history of politrauma presented with a nodular mass of the left false vocal cord, associated with progressive dysphonia, dyspnoea, and dysphagia. A computed tomography scan of the neck region showed a rounded and circumscribed mass without infiltration of the surrounding tissues. Histological investigation of the nodule revealed the presence of fibroelastic cartilaginous tissue, surrounded by a thin rim of fibrous tissue, with rare hypercellular areas, occasional binucleated cells, slight hyperchromasia, and an irregular nuclear profile. Mitotic activity was absent. The patient's history of laryngeal trauma, with the subsequent progressive onset of clinical symptoms, helps to distinguish the chondrometaplastic nature of this nodule from true laryngeal cartilaginous tumours, such as chondroma and low grade chondrosarcoma.

Myoendothelial differentiation of human umbilical cord blood-derived stem cells in ischemic limb tissues

Human umbilical cord blood (UCB) contains high numbers of endothelial progenitors cells (EPCs) characterized by coexpression of CD34 and CD133 markers. Prior studies have shown that CD34+/CD133+ EPCs from the cord or peripheral blood (PB) can give rise to endothelial cells and induce angiogenesis in ischemic tissues. In the present study, it is shown that freshly isolated human cord blood CD34+ cells injected into ischemic adductor muscles gave rise to endothelial and, unexpectedly, to skeletal muscle cells in mice. In fact, the treated limbs exhibited enhanced arteriole length density and regenerating muscle fiber density. Under similar experimental conditions, CD34- cells did not enhance the formation of new arterioles and regenerating muscle fibers. In nonischemic limbs CD34+ cells increased arteriole length density but did not promote formation of new muscle fibers. Endothelial and myogenic differentiation ability was maintained in CD34+ cells after ex vivo expansion. Myogenic conversion of human cord blood CD34+ cells was also observed in vitro by coculture onto mouse myoblasts. These results show that human cord blood CD34+ cells differentiate into endothelial and skeletal muscle cells, thus providing an indication of human EPCs plasticity. The full text of this article is available online at http://www.circresaha.org.