UVM Theses and Dissertations
Format:
Print
Author:
Lathrop Macura, Sherrill
Dept./Program:
Cell and Molecular Biology Program
Year:
2012
Degree:
Ph. D.
Abstract:
Malignant mesothelioma (MM) is a fatal disease often associated with exposure to asbestos fibers. The long latency period (30-40 years), heterogeneity of the disease, and difficulties in diagnosis, make treatment challenging. Systemic toxicity of currently approved treatment regimens and average survival times (less than 2 years) emphasize the need for novel treatment strategies. Research utilizing particulate materials for in vivo applications such as imaging, drug delivery, and even combined therapy/imaging agents for detection and treatment of diseases is a rapidly expanding field. Approaches using nanoparticles, because they can enter organelles and distribute widely throughout the body, raise concern about the possible associated acute and/or chronic toxicities. Microparticles, with their larger size, may be a less toxic alternative that still can be modified with the same array of functionalities as nanoparticles.
Acid-prepared mesoporous spheres (APMS), composed of silica and with an average diameter of 1.5 um, are readily taken up by cells when modified with tetraethylene glycol (TEG) on their external surfaces. To visualize our particles in vivo; we used a known ligand to immobilize gadolinium (III) (Gd) to the pores of APMS and imaged animals via magnetic resonance imaging (MRI). We show for the first time that porous silica microparticles containing a Gd chelate can be injected intraperitoneally (IP) and tracked in real-time by MRI. Biodistribution of APMS was examined in major organs, peritoneal lavage fluid (PLF) and urine of normal mice and rats.
After verification of increased mesothelin in human MMs injected into severe combined immunodeficient mice (SCID), APMS were then functionalized with an antibody to mesothelin (APMS-MB) or bovine serum albumin (BSA), a nonspecific protein control. Tumor targeting was evaluated by inductively-coupled plasma mass spectrometry and muItifluorescence confocal microscopy. Targeting with APMS-MB increased APMS uptake in mesenteric tumors at 6 days. Approximately 10-12% of the initially injected amount was observed in both spheroid and mesenteric MM at this time point.
Finally, we show that doxorubicin (DOX)-loaded APMS functionalized with a mesothelin-specific antibody (APMS-MB-DOX) is an effective targeting strategy in an IP mouse xenograft model of human MM. The health and weight over time, tumor volume/weight, profiles of immune cells in PLF, pathology of major organs, and the extent of tumor necrosis and cell proliferation were evaluated in MM-bearing mice following treatment with saline, DOX at high (0.2 mg/kg) and low (0.05 mglkg) concentrations, APMS-MB (no DOX), or APMS-MB-DOX (0.05 mglkg). Targeted therapy using APMS-MB-DOX (0.05 mglkg) was more effective than treatment with DOX alone and resulted in the reduction of tumor volume, no weight loss nor organ toxicity, and decreased cell proliferation in MM tumors compared to saline treated controls or animals treated with DOX alone. Our data suggest that targeted therapy results in greater efficacy with fewer adverse side effects than DOX alone, and that APMS-MB-DOX is an attractive vehicle for localized drug delivery for MM and other tumors (ovarian and pancreatic) that over-express mesothelin.
Acid-prepared mesoporous spheres (APMS), composed of silica and with an average diameter of 1.5 um, are readily taken up by cells when modified with tetraethylene glycol (TEG) on their external surfaces. To visualize our particles in vivo; we used a known ligand to immobilize gadolinium (III) (Gd) to the pores of APMS and imaged animals via magnetic resonance imaging (MRI). We show for the first time that porous silica microparticles containing a Gd chelate can be injected intraperitoneally (IP) and tracked in real-time by MRI. Biodistribution of APMS was examined in major organs, peritoneal lavage fluid (PLF) and urine of normal mice and rats.
After verification of increased mesothelin in human MMs injected into severe combined immunodeficient mice (SCID), APMS were then functionalized with an antibody to mesothelin (APMS-MB) or bovine serum albumin (BSA), a nonspecific protein control. Tumor targeting was evaluated by inductively-coupled plasma mass spectrometry and muItifluorescence confocal microscopy. Targeting with APMS-MB increased APMS uptake in mesenteric tumors at 6 days. Approximately 10-12% of the initially injected amount was observed in both spheroid and mesenteric MM at this time point.
Finally, we show that doxorubicin (DOX)-loaded APMS functionalized with a mesothelin-specific antibody (APMS-MB-DOX) is an effective targeting strategy in an IP mouse xenograft model of human MM. The health and weight over time, tumor volume/weight, profiles of immune cells in PLF, pathology of major organs, and the extent of tumor necrosis and cell proliferation were evaluated in MM-bearing mice following treatment with saline, DOX at high (0.2 mg/kg) and low (0.05 mglkg) concentrations, APMS-MB (no DOX), or APMS-MB-DOX (0.05 mglkg). Targeted therapy using APMS-MB-DOX (0.05 mglkg) was more effective than treatment with DOX alone and resulted in the reduction of tumor volume, no weight loss nor organ toxicity, and decreased cell proliferation in MM tumors compared to saline treated controls or animals treated with DOX alone. Our data suggest that targeted therapy results in greater efficacy with fewer adverse side effects than DOX alone, and that APMS-MB-DOX is an attractive vehicle for localized drug delivery for MM and other tumors (ovarian and pancreatic) that over-express mesothelin.