Novel integrative methodology for engineering large liver tissue equivalents based on three-dimensional scaffold fabrication and cellular aggregate assembly.

A novel engineering methodology for organizing a large liver tissue equivalent was established by intergrating both 'top down' and 'bottom up' approaches. A three-dimensional (3D) scaffold was engineered comprising 43 culture chambers (volume: 11.63 cm(3)) assembled in a symmetrical pattern on 3 layers, a design which enables further scaling up of the device to a clinically significant size (volume: 500 cm(3)). In addition, an inter-connected flow channel network was designed and proved to homogenously deliver culture medium to each chamber with the same pressure drop. After fabrication using nylon-12 and a selective laser sintering process, co-cultured cellular aggregates of human hepatoma Hep G2 and TMNK-1 cells were loosely packed into the culture chambers with biodegradable poly-L-lactic acid fibre pieces for 9 days of perfusion culture. The device enabled increased hepatic function and well-maintained cell viability, demonstrating the importance of an independent medium flow supply for cell growth and function provided by the current 3D scaffold. This integrative methodology from the macro- to the micro-scale provides an efficient way of arranging engineered liver tissue with improved mass transfer, making it possible to further scale up to a construct with clinically relevant size while maintaining high per-volume-based physiological function in the near future.

Liver tissue engineering based on aggregate assembly: efficient formation of endothelialized rat hepatocyte aggregates and their immobilization with biodegradable fibres.

To realize long-term in vitro culture of hepatocytes at a high density while maintaining a high hepatic function for aggregate-based liver tissue engineering, we report here a novel culture method whereby endothelialized rat hepatocyte aggregates were formed using a PDMS microwell device and cultured in a perfusion bioreactor by introducing spacers between aggregates to improve oxygen and nutrient supply. Primary rat hepatocyte aggregates around 100 µm in diameter coated with human umbilical vein endothelial cells were spontaneously and quickly formed after 12 h of incubation, thanks to the continuous supply of oxygen by diffusion through the PDMS honeycomb microwell device. Then, the recovered endothelialized rat hepatocyte aggregates were mixed with biodegradable poly-l-lactic acid fibres in suspension and packed into a PDMS-based bioreactor. Perfusion culture of 7 days was successfully achieved with more than 73.8% cells retained in the bioreactor. As expected, the fibres acted as spacers between aggregates, which was evidenced from the enhanced albumin production and more spherical morphology compared with fibre-free packing. In summary, this study shows the advantages of using PDMS-based microwells to form heterotypic aggregates and also demonstrates the feasibility of spacing tissue elements for improving oxygen and nutrient supply to tissue engineering based on modular assembly.

Engineering of implantable liver tissues.

In this chapter, from the engineering point of view, we introduce the results from our group and related research on three typical configurations of engineered liver tissues; cell sheet-based tissues, sheet-like macroporous scaffold-based tissues, and tissues based on special scaffolds that comprise a flow channel network. The former two do not necessitate in vitro prevascularization and are thus promising in actual human clinical trials for liver diseases that can be recovered by relatively smaller tissue mass. The third approach can implant a much larger mass but is still not yet feasible. In all cases, oxygen supply is the key engineering factor. For the first configuration, direct oxygen supply using an oxygen-permeable polydimethylsiloxane membrane enables various liver cells to exhibit distinct behaviors, complete double layers of mature hepatocytes and fibroblasts, spontaneous thick tissue formation of hepatocarcinoma cells and fetal hepatocytes. Actual oxygen concentration at the cell level can be strictly controlled in this culture system. Using this property, we found that initially low then subsequently high oxygen concentrations were favorable to growth and maturation of fetal cells. For the second configuration, combination of poly-L: -lactic acid 3D scaffolds and appropriate growth factor cocktails provides a suitable microenvironment for the maturation of cells in vitro but the cell growth is limited to a certain distance from the inner surfaces of the macropores. However, implantation to the mesentery leaves of animals allows the cells again to proliferate and pack the remaining spaces of the macroporous structure, suggesting the high feasibility of 3D culture of hepatocyte progenitors for liver tissue-based therapies. For the third configuration, we proposed a design criterion concerning the dimensions of flow channels based on oxygen diffusion and consumption around the channel. Due to the current limitation in the resolution of 3D microfabrication processes, final cell densities were less than one-tenth of those of in vivo liver tissues; cells preferentially grew along the surfaces of the channels and this fact suggested the necessity of improved 3D fabrication technologies with higher resolution. In any case, suitable oxygen supply, meeting the cellular demand at physiological concentrations, was the most important factor that should be considered in engineering liver tissues. This enables cells to utilize aerobic respiration that produces almost 20 times more ATP from the same glucose consumption than anaerobic respiration (glycolysis). This also allows the cells to exhibit their maximum reorganization capability that cannot be observed in conventional anaerobic conditions.

[Associated Langerhans cell histiocytosis and Erdheim-Chester disease]. / Association d'une histiocytose langerhansienne à une maladie d'Erdheim-Chester.

BACKGROUND: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis with multiple organ involvement affecting middle-aged adults. A case of ECD associated with Langerhans cell histiocytosis (LCH) is reported herein. CASE REPORT: A 75-year-old woman presented maculopapular skin lesions on her trunk, associated with constrictive pericarditis and pleurisy present for 1 year. The skin biopsy militated in favour of LCH since it revealed a histiocytic infiltrate with a positive CD1a marker at immunohistochemistry (IHC). The association with ECD was diagnosed on the basis of pericarditis, periaortitis, pleurisy, pulmonary involvement and retroperitoneal fibrosis. The patient was treated with interferon-α2a with good initial results, but died from septic shock a year and a half later, a few months after discontinuing interferon due to poor tolerability. DISCUSSION: The clinical, radiographic and histological arguments in favour of ECD clearly differ from those for LCH. However, as already reported, the two illnesses may be associated, thus underlining the possible existence of a link between these two histiocytic proliferations emanating from the same medullary precursor. Two hypotheses have been advanced in an attempt to explain this association: the first involves a stimulus that might lead to independent proliferation of the two cell lines while the second suggests the existence of a transformation pathway from one form of proliferation to the other. CONCLUSION: Screening for associated ECD should be routinely performed in patients presenting LCH with signs evocative of ECD.

[An atypical presentation of primary cutaneous diffuse B-cell lymphoma, leg type]. / Une présentation atypique de lymphome cutané B primitif à grandes cellules de type jambe.

BACKGROUND: Primary cutaneous diffuse B-cell lymphoma, leg type, are rare and aggressive tumours frequently affecting elderly patients. We present a case of a 53-year-old woman with an atypical presentation of primary cutaneous diffuse B-cell lymphoma, leg type. CASE REPORT: Eight years after complete excision of a Jessner-Kanof lymphocytic infiltration on the right shoulder, the patient developed a primary cutaneous diffuse B-cell lymphoma, leg type at the same site. The isolated lesion was treated using local radiotherapy. One year later, the patient presented headache associated with a temporal lesion, and biopsy confirmed a relapse. Cerebral CT scan showed an osteolytic temporal lesion while the other investigations revealed no extracutaneous extension. She was treated with R-CHOP chemotherapy and intrathecal methotrexate due to the osteolytic lesion. DISCUSSION: The particularity of this case consists in the age of this woman, who was younger than the average, the two atypical localizations on the shoulder, then the temple, and osteolysis, which is not the most frequent extension. Furthermore, to our knowledge, transformation of a Jessner-Kanof lesion into local aggressive primary cutaneous diffuse B-cell lymphoma, leg type, has not been yet described.

Avidin-biotin-based approach to forming heterotypic cell clusters and cell sheets on a gas-permeable membrane.

Implantation of sheet-like liver tissues is a promising method in hepatocyte-based therapies, because angiogenesis is expected to occur upon implantation from the surrounding tissues. In this context, we introduce here a new methodology for the formation of a functional thick hepatic tissue usable for cell sheet technology. First, we report the formation of composite tissue elements in suspension culture. Composite elements were composed of human hepatoma Hep G2 cells and mouse NIH/3T3 fibroblasts which are important modulators for thick-tissue formation. To overcome the very low attachment and organization capability between different cells in suspension, we synthesized a new cell-to-cell binding molecule based on the avidin-biotin binding system that we previously applied to attach hepatocytes on artificial substrata. This newly synthesized biotin-conjugated biocompatible anchoring molecule was inserted in the plasma membrane of both cell types. NIH/3T3 cells were further conjugated with avidin and incubated with biotin-presenting Hep G2 cells to form highly composite tissue elements. Then, we seeded those elements on highly gas-permeable membranes at their closest packing density to induce the formation of a thick, composite, functional hepatic tissue without any perfusion. This methodology could open a new way to engineer implantable thick liver tissue sheets where different cell types are spatially organized and well supplied with oxygen.

Laser sintering fabrication of three-dimensional tissue engineering scaffolds with a flow channel network.

The fabrication of tissue engineering scaffolds for the reconstruction of highly oxygen-dependent inner organs is discussed. An additive manufacturing technology known as selective laser sintering was employed to fabricate a highly porous scaffold with an embedded flow channel network. A porogen leaching system was used to obtain high porosity. A prototype was developed using the biodegradable plastic polycaprolactone and sodium chloride as the porogen. A high porosity of 90% was successfully obtained. Micro x-ray CT observation was carried out to confirm that channels with a diameter of approximately 1 mm were generated without clogging. The amount of residual salt was 930 µg while the overall volume of the scaffold was 13 cm(3), and it was confirmed that the toxicity of the salt was negligible. The hydrophilization of the scaffold to improve cell adhesion on the scaffold is also discussed. Oxygen plasma ashing and hydrolysis with sodium hydroxide, typically employed to improve the hydrophilicity of plastic surfaces, were tested. The improvement of hydrophilicity was confirmed by an increase in water retention by the porous scaffold from 180% to 500%.

Composite renal cell carcinoma with clear cell renal cell carcinomatous and carcinoid tumoral elements: a first case report.

Renal endocrine tumours are extremely rare, and carcinoid tumoral elements in renal cell carcinoma have never been reported. This is the first report of a composite renal cell carcinoma containing a clear cell renal cell carcinoma associated with carcinoid tumoral elements, in a patient with synchronous metastatic disease. In the absence of specific radiological and clinical manifestations, typical morphological features as well as an immunostaining profile of neuroendocrine differentiation were identified by microscopy. Secondary nodal and liver localisations were characterised by carcinoid elements only. Despite antiangiogenic therapy, liver metastasis progressed, suggesting that adjuvant therapy cannot be based on the presence of the clear cell renal cell carcinoma component. In this context, extensive tissue sampling is recommended to reveal the endocrine component that is the most aggressive element of such a composite carcinoma.

[Primary leiomyosarcoma of the epididymis: a case report with review of the literature]. / Léiomyosarcome de l'épididyme : à propos d'un cas avec revue de la littérature.

Primary epididymal leiomyosarcoma is uncommon: only 16 cases has been reported in the literature. We present an additionnal case in a 78-year-old man, treated for a prostatic adenocarcinoma by gonadorelin (LH-RH) analogue, who had an epididymal tumor. A right orchidectomy with high ligation of the spermatic cord was performed. The diagnostic of primary leiomyosarcoma of the epididymis was made. The patient is dead 2 years later with no recurrence of disease. A review of reported cases is made.

Reactive nodular fibrous pseudotumor: a first report of gastric localization and clinicopathologic review.

Reactive nodular fibrous pseudotumor (RNFP) of the gastrointestinal tract is a distinct benign lesion, which could originate from a reactive proliferation of multipotential subserosal cells. This is the first case to be reported in the stomach. It was fortuitously discovered in a 60-year-old man with history of bulbar ulcer and gastritis. Gross examination revealed three lesions in the gastric wall and an adjacent lesion in the lesser omentum. Histologically, lesions were composed of a proliferation of spindle and stellate cells in a dense collagenic hyalinized background containing a mononuclear cell inflammatory infiltrate with numerous lymphoid aggregates and plasma cells with perivascular disposition. Immunohistochemistry showed staining for cytokeratins (AE1/AE3), vimentin and smooth muscle actin, without staining for the neurofilament and S100 proteins, synaptophysin, calretinin, CD117 (c-kit), CD34, desmin, caldesmon or anaplastic lymphoma kinase (ALK-1). Complete excision was performed, and no evidence of disease was found 4 months later. After analysing clinical, morphological and immunohistochemical features of this entity, the main differential diagnoses will be discussed, including calcifying fibrous pseudotumor, which shares morphological characteristics with RNFP, but which immunohistochemistry and the ultrastructural study suggest that it may be a result of another reactive process.

Altered endothelial gene expression associated with hereditary haemorrhagic telangiectasia.

BACKGROUND: Mutations in endoglin (ENG) and activin receptor-like kinase 1 (ALK-1 or ACVRL1) genes are the underlying basis of hereditary haemorrhagic telangiectasia (HHT) types 1 and 2, respectively. Both genes belong to the transforming growth factor-beta (TGF-beta) receptors superfamily and are expressed in endothelial cells. The current model for HHT is that ENG or ALK-1 haplo-insufficiency affects angiogenesis and predisposes to vascular dysplasia and arteriovenous malformations. MATERIALS AND METHODS: Using microarray technology, we compared human umbilical vein endothelial cells (HUVEC) from newborns with ENG or ALK-1 mutations to control cells to search for gene profiles associated with early stages of the disease. Real-time polymerase chain reaction and Western blot analysis were used to validate a subset of the modulated genes and functionally related genes. RESULTS: Our results indicate that HHT endothelial cells in vitro display several gene expression disturbances, including genes associated with the activation phase of angiogenesis, with cell guidance and intercellular connections, and also with the TGF-beta pathway. Hierarchical clustering using modulated genes enables discrimination between affected and non-affected samples. CONCLUSION: HHT HUVECs display gene modulations which can suggest that ENG and ALK-1 haplo-insufficiency induces compensatory regulatory mechanisms at the expression levels.

[A marginal zone-B cell lymphoma revealed by platelet satellitism and lympho-agglutination phenomenon around atypical lymphocytes]. / Satellitisme plaquettaire et lympho-agglutination exclusivement aux lymphocytes atypiques révélant un lymphome B de la zone marginale.

A 48-year-old man, with persistent pyrexia, presented with thrombocytopenia and lymphocytosis. The peripheral blood smears showed atypical lymphocytes and a platelet satellitism phenomenon around atypical lymphocytes associated to lympho-agglutination. Platelet satellitism was exclusively observed with atypical lymphocytes in EDTA-treated blood and at room temperature. This phenomenon was not observed when adding normal plasma and could be reproduced several times. Flow cytometry analysis of the peripheral blood, cytological and histological studies revealed a marginal zone-B cell lymphoma. The mechanism underlying platelet satellitism is not fully understood, but is likely to involve an immunologic binding of EDTA-dependent antiplatelet autoantibodies directed against the platelets glycoprotein IIb/IIIa complex. The association between platelet satellitism and lymphoma could also involve a monoclonal Ig secreted by lymphoma cells.