Cell sheet engineering for reproducing the bone marrow hematopoietic stem cell niche

Hematopoietic stem and progenitor cells (HSPC) are multipotent cells responsible for the maintenance and renewal of the hematopoietic lineage in the adult body. The fate of these stem cells is closely regulated by their surrounding microenvironment, or niche. The importance of the microenvironment for HSPC function has been long recognized by researchers that more than 30 years ago attempted to emulate it in 2D using a layer of bone marrow stromal cells to culture hematopoietic cells for long time periods (Dexter-type cultures). However, all the models based on feeder layers are less than perfect in recreating the hematopoietic microenvironment. The use of growth factor cocktails provided some promising results concerning the maintenance and proliferation of some cell populations but still struggle to deliver the correct microenvironment for the maintenance of suitable HSPC populations. Part of the problem of the current systems lies on the lack of the third dimension. At the same time, the proposed three-dimensional methodologies using scaffolds to engineer the bone marrow (BM) microenvironment present very limited results probably due to the scaffolding matrices’ intrinsic limitations. Therefore, an engineered BM microenvironment capable of acting as a functional HSPC niche would provide a tremendous tool for the study of hematopoiesis as well as for obtaining and maintaining HSPC. Using osteogenic cell sheets, we have previously demonstrated that it was possible to induce the ectopic formation of mature bone tissue with a clear bone marrow, avoiding the use of scaffolds. In the present work, we studied the potential of using osteogenic cell sheets to build in vitro, a 3D microenvironment capable of providing HSPC a suitable niche for their survival and proliferation. For this, we used bone marrow stromal cells and adipose-derived stem cells to produce the osteogenic cell sheets and human umbilical cord blood as a source of hematopoietic stem cells

Silk fibroin scaffolds enhance cell commitment of adult rat cardiac progenitor cells.

The use of three-dimensional (3D) cultures may induce cardiac progenitor cells to synthesize their own extracellular matrix (ECM) and sarcomeric proteins to initiate cardiac differentiation. 3D cultures grown on synthetic scaffolds may favour the implantation and survival of stem cells for cell therapy when pharmacological therapies are not efficient in curing cardiovascular diseases and when organ transplantation remains the only treatment able to rescue the patient’s life. Silk fibroin-based scaffolds may be used to increase cell affinity to biomaterials and may be chemically modified to improve cell adhesion. In the present study, porous, partially orientated and electrospun nanometric nets were used. Cardiac progenitor cells isolated from adult rats were seeded by capillarity in the 3D structures and cultured inside inserts for 21 days. Under this condition, the cells expressed a high level of sarcomeric and cardiac proteins and synthesized a great quantity of ECM. In particular, partially orientated scaffolds induced the synthesis of titin, which is a fundamental protein in sarcomere assembly

Association of Systemic Lupus Erythematosus Clinical Features with European Population Genetic Substructure

Systemic Lupus Erythematosus (SLE) is an autoimmune disease with a very varied spectrum of clinical manifestations that could be partly determined by genetic factors. We aimed to determine the relationship between prevalence of 11 clinical features and age of disease onset with European population genetic substructure. Data from 1413 patients of European ancestry recruited in nine countries was tested for association with genotypes of top ancestry informative markers. This analysis was done with logistic regression between phenotypes and genotypes or principal components extracted from them. We used a genetic additive model and adjusted for gender and disease duration. Three clinical features showed association with ancestry informative markers: autoantibody production defined as immunologic disorder (P = 6.8×10(-4)), oral ulcers (P = 6.9×10(-4)) and photosensitivity (P = 0.002). Immunologic disorder was associated with genotypes more common in Southern European ancestries, whereas the opposite trend was observed for photosensitivity. Oral ulcers were specifically more common in patients of Spanish and Portuguese self-reported ancestry. These results should be taken into account in future research and suggest new hypotheses and possible underlying mechanisms to be investigated. A first hypothesis linking photosensitivity with variation in skin pigmentation is suggested

Lack of replication of higher genetic risk load in men than in women with systemic lupus erythematosus

Introduction: We aimed to replicate a recent study which showed higher genetic risk load at 15 loci in men than in women with systemic lupus erythematosus (SLE). This difference was very significant, and it was interpreted as indicating that men require more genetic susceptibility than women to develop SLE. Methods: Nineteen SLE-associated loci (thirteen of which are shared with the previous study) were analyzed in 1,457 SLE patients and 1,728 healthy controls of European ancestry. Genetic risk load was calculated as sex-specific sum genetic risk scores (GRS(s)). Results: Our results did not replicate those of the previous study at either the level of individual loci or the global level of GRS(s). GRS(s) were larger in women than in men (4.20 ± 1.07 in women vs. 3.27 ± 0.98 in men). This very significant difference (P < 10(-16)) was more dependent on the six new loci not included in the previous study (59% of the difference) than on the thirteen loci that are shared (the remaining 41%). However, the 13 shared loci also showed a higher genetic risk load in women than in men in our study (P = 6.6 × 10(-7)), suggesting that heterogeneity of participants, in addition to different loci, contributed to the opposite results. Conclusion: Our results show the lack of a clear trend toward higher genetic risk in one of the sexes for the analyzed SLE loci. They also highlight several limitations of assessments of genetic risk load, including the possibility of ascertainment bias with loci discovered in studies that have included mainly women

Mixed cryoglobulinemia

Mixed cryoglobulinemia (MC), type II and type III, refers to the presence of circulating cryoprecipitable immune complexes in the serum and manifests clinically by a classical triad of purpura, weakness and arthralgias. It is considered to be a rare disorder, but its true prevalence remains unknown. The disease is more common in Southern Europe than in Northern Europe or Northern America. The prevalence of 'essential' MC is reported as approximately 1:100,000 (with a female-to-male ratio 3:1), but this term is now used to refer to a minority of MC patients only. MC is characterized by variable organ involvement including skin lesions (orthostatic purpura, ulcers), chronic hepatitis, membranoproliferative glomerulonephritis, peripheral neuropathy, diffuse vasculitis, and, less frequently, interstitial lung involvement and endocrine disorders. Some patients may develop lymphatic and hepatic malignancies, usually as a late complication. MC may be associated with numerous infectious or immunological diseases. When isolated, MC may represent a distinct disease, the so-called 'essential' MC. The etiopathogenesis of MC is not completely understood. Hepatitis C virus (HCV) infection is suggested to play a causative role, with the contribution of genetic and/or environmental factors. Moreover, MC may be associated with other infectious agents or immunological disorders, such as human immunodeficiency virus (HIV) infection or primary Sjögren's syndrome. Diagnosis is based on clinical and laboratory findings. Circulating mixed cryoglobulins, low C4 levels and orthostatic skin purpura are the hallmarks of the disease. Leukocytoclastic vasculitis involving medium- and, more often, small-sized blood vessels is the typical pathological finding, easily detectable by means of skin biopsy of recent vasculitic lesions. Differential diagnoses include a wide range of systemic, infectious and neoplastic disorders, mainly autoimmune hepatitis, Sjögren's syndrome, polyarthritis, and B-cell lymphomas. The first-line treatment of MC should focus on eradication of HCV by combined interferon-ribavirin treatment. Pathogenetic treatments (immunosuppressors, corticosteroids, and/or plasmapheresis) should be tailored to each patient according to the progression and severity of the clinical manifestations. Long-term monitoring is recommended in all MC patients to assure timely diagnosis and treatment of the life-threatening complications. The overall prognosis is poorer in patients with renal disease, liver failure, lymphoproliferative disease and malignancies

PHYSICAL CHARACTERIZATION OF LAYERED PEROVSKITES-POLYSTYRENE COMPOSITES

The layered perovskites show a solid-solid transition at a temp. which is dependent on the no. of C atoms in the hydrocarbon chains and on the nature of the metal atom. The composite of polystyrene [9003-53-6] with (n-C12H25NH3)2MnCl4 [75899-75-1] shows relatively good mech. properties even at high filler content. These properties, coupled with excellent thermal properties due to the thermally active filler inside the polymer matrix, make the title composites potentially useful in thermal-energy storag

IN-SITU POLYMERIZATION OF FUNCTIONAL MONOMERS IN RUBBERS .1. MODIFICATION OF SILICONE RUBBERS BY A POLY(ESTER THIOETHER AMINE) BASED ON PIPERAZINE

Modified silicone rubber intended mainly for biomedical applications was obtained by in situ polymerization. The process involved swelling of the rubber with a mixture of solvent and monomers, polymerization, and finally evaporating the solvent under reduced pressure. The polymerization system selected was the stepwise hydrogen-transfer polyaddition of 1,4-piperazinediyl diethanethiol to ethylene glycol dimethacrylate, leading to a poly(ester thioether amine). The modified silicone was physically and mechanically characterized by several analytical techniques (Fourier-transform infra-red spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, dynamic contact angle and scanning electron microscopy), and the results obtained were compared with those relative to both the linear guest polymer and the unmodified rubber