Waleed S W Shalaby

Christiana Care Health System, Wilmington, Delaware, United States

Are you Waleed S W Shalaby?

Claim your profile

Publications (4)16.55 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Polymeric controlled delivery systems hold great promise in the field of modern medicine. Such technology has already been converted into commercially viable products in a myriad of fields. Chemotherapy is an example of such an area where constant efficacious levels of drug can greatly enhance clinical outcomes. The key to designing such therapies is the preparation of the proper delivery system. To this end, a series of bioresorbable polyether-ester-carbonate copolymers have been developed, which when combined with a diluent, are capable injection into the body and consistently forming a drug delivery depot. The study delineated here aimed at producing a more effective treatment of a common drug, paclitaxel, using the polymeric carrier. The polymer carrier system exhibited controlled release of paclitaxel both in vitro and in vivo. Drug concentrations were analyzed by high performance liquid chromatography and apoptotic activity was confirmed through flow cytometry. Relevant success was exhibited by the regression of tumor size following a multiple injection treatment regimen in a murine xenograft model. This multiple injection treatment shows promising results when compared to the traditional paclitaxel paradigm of a single injection for a period of 3 weeks.
    Journal of Biomedical Materials Research Part A 04/2012; 100(9):2365-72. · 2.83 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An absorbable microparticulate cation exchanger was synthesized as a versatile carrier for biologically active proteins. In this work, acid-terminated polyglycolide (or polyglycolic acid) microparticulates (PG-MP) were surface modified for either sustained release of cytokines or as a platform for immunomodulation. The intended goal was to achieve in situ recruitment/maturation of dendritic cells and activation of T cells for tumor immunotherapy. PG-MP were prepared with a volume weighted mean diameter of 7.02 micro (range: 2.09-14.58 micro). Accessible carboxylic acid groups were determined to be 0.3 mmol/g with a corresponding zeta potential of -21.87 mV in phosphate-buffered saline. Under low magnification, scanning electron microscopy (SEM) revealed a highly textured surface due to processing from repetitive jet milling. However, a moderately porous architecture was noted at higher magnification. Electron spectroscopy for chemical analysis was used to characterize the PG-MP surface before and after adsorption of human granulocyte-macrophage colony stimulating factor (GM-CSF). Adsorption of GM-CSF on PG-MP (PG-GMCSF) resulted in a modest increase in the surface atomic concentration of nitrogen (0.97%). Pretreating the surface with poly-L-lysine (PG/Lys-GMCSF) prior to adding GM-CSF produced a nearly threefold increase in the surface nitrogen concentration (4.20% compared to 1.47%). This manipulation not only increased loading content, but also prolonged the release of GM-CSF released from 6 days to 26 days. ESCA on the post-release PG-MP samples (PG-GMCSF and PG/Lys-GMCSF) revealed a similar residual surface nitrogen concentration (2.26% vs. 2.35%). The observation was consistent with irreversibly adsorbed GM-CSF. It is postulated that irreversibly bound GM-CSF is released over time as a function of microparticulate degradation. Biological activity of released GM-CSF was confirmed by the proliferation of a GM-CSF-dependent cell line (TF-1) in the presence of microparticulates. PG-MP mediated activation of T cells was achieved through irreversible adsorption of either antimouse cd3 plus antimouse cd28 monoclonal antibodies (alpha-cd3/cd28-MP) or antihuman CD3 plus antihuman CD28 monoclonal antibodies (alpha-CD3/CD28-MP) on PG-MP. Irreversibly adsorbed antibodies were capable of activating both resting mouse and human T cells. Intracellular flow cytometry on mouse T cells revealed that nearly 50% of the activated cells produced interferon-gamma (IFN-gamma). This was consistent with a TH-1 or cell-mediated response. In vivo efficacy was evaluated in a mouse flank tumor model showing a significant antitumor effect both alone and in combination. Combination therapy was most effective at preventing tumor implantation (8/8 mice) and was able induce tumor regression (4/7 mice) and/or stable disease (3/7 mice) in a regression model. In these studies, immunohistochemistry was used to confirm local recruitment of dendritic cells. In conclusion, the PG-MP represents a novel absorbable cation exchanger that can be readily manipulated to deliver biologically active proteins for immunotherapy.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 06/2004; 69(2):173-82. · 2.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Acid-terminated polyglycolide microparticles (PG-MP) were prepared as a versatile substrate that could be surface-modified for either immobilization of anti-cd3 and anti-cd28 mAb to activate T cells or sustained release of granulocyte-macrophage colony stimulating factor (GM-CSF) for dendritic cell (DC) recruitment and maturation. PG-MP were prepared with a volume-weighted mean diameter of 56 or 57 microm. Accessible carboxylic acid group concentration was determined by potentiometric titration to be 0.3 mmole/g and corresponded to a zeta potential of -21.87 mV. PG-MP immobilized with either anti-human CD3/CD28 or anti-mouse cd3/cd28 induced significant proliferation of T cells. Intracellular flow cytometry in activated mouse T cells was significant for IFN-gamma, but not IL-4. Microparticles surface-modified for GM-CSF release were prepared from either PG-MP or PG pre-treated with poly-L-lysine (PG-Lys) to manipulate surface charge. GM-CSF released from PG-Lys-MP was observed for up to 26 days. The biologic activity of released GM-CSF was confirmed by using a h-GM-CSF-dependent cell line. The efficacy of the alpha-cd3/cd28-MP and GMCSF-MP was studied in a syngeneic mouse tumor prevention and regression model. Co-injection of Meth A fibrosarcoma cells with alpha-cd3/cd28-MP and GMCSF-MP completely prevented tumor implantation (0/24). The regression model showed complete tumor regression in four of seven animals and stable disease in three of seven. In the latter study, a dramatic level of DC infiltration was observed compared to controls.
    Journal of Controlled Release 09/2003; 91(1-2):209-24. · 7.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We compared the ability of two genetically modified myeloid cells, K562 and U937, to serve as artificial antigen-presenting cells (aAPC). Both aAPC were stably transfected with the low-affinity Fcgamma receptor CD32 (K32/U32 cells). K32 cells loaded with anti-CD3 and anti-CD28 Ab (K32/CD3/28) induced more rapid CD4 T-cell expansion than CD3/28-coated beads. In contrast, U32/CD3/28 induced high levels of CD4 T-cell thymidine uptake but were unable to sustain long-term T-cell expansion. K32 cells, but not U32 cells, loaded with anti-CD3 alone also stimulated CD4 T-cell growth and IL-2 secretion, indicating the expression of additional costimulatory molecules on K32 cells. We found constitutive expression of B7-H3 and a strong upregulation of mRNA encoding for IL-15, PD-L1, and PD-L2 after coculture with CD4 T cells activated by K32/CD3/28 but not U32/CD3/28. We conclude that K32 aAPCs are a robust system for clinical scale ex vivo expansion of CD4 T cells.
    Clinical Immunology 01/2003; 105(3):259-72. · 3.77 Impact Factor