Showing papers by "Rama Shanker Verma published in 2011"

Cardiogel supports adhesion, proliferation and differentiation of stem cells with increased oxidative stress protection.

Abstract: Cultured murine bone marrow derived mesenchymal stem cells (BMSC) when grown along with cardiogel derived from mouse cardiac fibroblast, exhibited increased cell proliferation and differentiation and enhanced survival under oxidative stress induced by the exposure of H2O2 in vitro (similar to in vivo ischemia like condition) Adhesion of BMSC to the cardiogel occurred at a faster rate when compared to the cells grown on normal surface BMSC attached to cardiogel showed an increased resistance to proteolytic (enzymatic) disassociation This is the first report on an attempt to use an in house biomaterial for the growth of BMSC that led to their heightened resistance towards oxidative stress These studies support that cardiogel is an efficient biodegradable three-dimensional extracellular matrix which supports better growth of BMSC and can be used as a scaffold for stem cell delivery, with potential therapeutic applications in cardiac tissue regeneration

Inflammatory responses of tissue-engineered xenografts in a clinical scenario

Abstract: Acellular tissue-engineered (ATE) xenografts and homografts are used in clinical cardiovascular surgery. The present study examined the specific role of carbohydrate antigen (α-Gal and T-antigen) in immune response after decellularisation in tissue-engineered xenografts (porcine pulmonary artery and bovine jugular vein). An enzyme-linked immunosorbent assay (ELISA) was used to ascertain whether implantation of bioprostheses, ATE xenografts and mechanical valve replacement result in augmentation of anti-α-Gal IgM antibodies within eight days of surgery (each group, n=6). Kinetics of host inflammatory response on surgically explanted ATE xenografts was also studied. Immunostaining for α-Gal and T-antigen detected the presence of them in the native tissue but they were absent in processed ATE xenografts from the same tissue. A significant increase in the concentration of anti-α-Gal IgM antibodies was observed in the serum of bioprosthetic valve recipients as compared to ATE xenograft recipients (P<0.05). Organised collagen, and decreased inflammatory response with increase in endothelisation and vascularisation was evident beyond one year of surgery as compared to early periods in ATE xenografts. This study demonstrates that decellularisation of xenografts and further processing of these tissues enabled reduction of inflammatory stimulus with autologous recellularisation with no calcification.

Targeting head and neck squamous cell carcinoma using a novel fusion toxin-diphtheria toxin/HN-1

Abstract: The current treatment strategies, chemotherapy and radiation therapy being used for the management of cancer are deficient in targeted approach leading to treatment related toxicities and relapse. Contrarily, fusion toxins exhibit remarkable tumor specificity thus emerging as an alternative therapy for the treatment of cancer. Diphtheria toxin-HN-1 peptide (DT/HN-1) is a fusion toxin designed to target the head and neck squamous cell carcinoma (HNSCC). The aim of this study was to construct, characterize, and evaluate the cytotoxicity and specificity of DT/HN-1 fusion toxin against the HNSCC cells. The purified DT/HN-1 fusion toxin was characterized by SDS-PAGE and western blotting. Refolding of purified fusion toxins was monitored by fluorescence spectra and circular dichroism spectra. The activity of DT/HN-1 fusion toxin was demonstrated on various HNSCC cell lines by cell viability assay, cell proliferation assay, protein synthesis inhibition assay, apoptosis and cell cycle analysis. The fusion toxin DT/HN-1 demonstrated remarkably high degree of cytotoxicity specific to the HNSCC cells. The IC50 of DT/HN-1 fusion toxin was ~1 to 5 nM in all the three HNSCC cell lines. The percentage apoptotic cells in DT/HN-1 treated UMB-SCC-745 cells are 16% compared to 4% in untreated. To further demonstrate the specific toxicity of DT/HN-1 fusion toxin towards the HNSCC cells we constructed, characterized and evaluated the efficacy of DT protein. The DT protein coding for only a fragment of diphtheria toxin without its native receptor binding domain failed to exhibit any cytotoxicity on all the cell lines used in this study thus establishing the importance of a ligand in achieving targeted toxicity. To evaluate the translocation ability of HN-1 peptide, an additional construct DTΔT/HN-1 was constructed, characterized and evaluated for its cytotoxic activity. The fusion toxin DTΔT/HN-1 deficient of the translocation domain of diphtheria toxin showed no cytotoxicity on all the cell lines clearly indicating the inability of HN-1 peptide to translocate catalytic domain of the toxin into the cytosol.

Specific targeting of Ep-CAM in various carcinomas by novel monoclonal antibodies.

Abstract: Epithelial cell adhesion molecule (Ep-CAM) is a 40 kDa transmembrane glycoprotein overexpressed in majority of tumor epithelial cells and has a major morphoregulatory function, relevant not only to epithelial tissue development, but also in carcinogenesis and tumor progression. Since Ep-CAM localizes at the cell surface of most carcinomas, the molecule is an attractive target for immunotherapy and several strategies have been deployed to treat cancer using Ep-CAM targeting, including MAb therapy. For improving effective targeting of this protein for diagnostics in various clinical samples, we generated and characterized an anti-Ep-CAM MAb (C4) using recombinant Ep-CAM protein, comprising the highly immunogenic domain. The specificity of C4-MAb was characterized in Ep-CAM positive cell lines (PC3 and MCF-7) by flow cytometry and immunofluorescence. The immunohistochemistry analysis in clinical tissue samples showed specific detection of epithelial antigens in breast, colon, stomach, and prostate carcinomas...