Brandon S. Brown

Synthetic nanoparticles functionalized with biomimetic leukocyte membranes possess cell-like functions

The therapeutic efficacy of systemic drug-delivery vehicles depends on their ability to evade the immune system, cross the biological barriers of the body and localize at target tissues. White blood cells of the immune system--known as leukocytes--possess all of these properties and exert their targeting ability through cellular membrane interactions. Here, we show that nanoporous silicon particles can successfully perform all these actions when they are coated with cellular membranes purified from leukocytes. These hybrid particles, called leukolike vectors, can avoid being cleared by the immune system. Furthermore, they can communicate with endothelial cells through receptor-ligand interactions, and transport and release a payload across an inflamed reconstructed endothelium. Moreover, leukolike vectors retained their functions when injected in vivo, showing enhanced circulation time and improved accumulation in a tumour.

Bromelain Surface Modification Increases the Diffusion of Silica Nanoparticles in the Tumor Extracellular Matrix

Tumor extracellular matrix (ECM) represents a major obstacle to the diffusion of therapeutics and drug delivery systems in cancer parenchyma. This biological barrier limits the efficacy of promising therapeutic approaches including the delivery of siRNA or agents intended for thermoablation. After extravasation due to the enhanced penetration and retention effect of tumor vasculature, typical nanotherapeutics are unable to reach the nonvascularized and anoxic regions deep within cancer parenchyma. Here, we developed a simple method to provide mesoporous silica nanoparticles (MSN) with a proteolytic surface. To this extent, we chose to conjugate MSN to Bromelain (Br–MSN), a crude enzymatic complex, purified from pineapple stems, that belongs to the peptidase papain family. This surface modification increased particle uptake in endothelial, macrophage, and cancer cell lines with minimal impact on cellular viability. Most importantly Br–MSN showed an increased ability to digest and diffuse in tumor ECM in vitro and in vivo.

Short and Long Term, In Vitro and In Vivo Correlations of Cellular and Tissue Responses to Mesoporous Silicon Nanovectors

The characterization of nanomaterials and their influence on and interactions with the biology of cells and tissues are still partially unknown. Multistage nanovectors based on mesoporous silicon have been extensively studied for drug delivery, thermal heating, and improved diagnostic imaging. Here, the short- and long-term changes occurring in human cells upon the internalization of mesoporous silicon nanovectors (MSV) are analyzed. Using qualitative and quantitative techniques as well as in vitro and in vivo biochemical, cellular, and functional assays, it is demonstrated that MSV do not cause any significant acute or chronic effects on cells and tissues. In vitro cell toxicity and viability are analyzed, as well as the maintenance of cell phase cycling and the architecture upon the internalization of MSV. In addition, it is evaluated whether MSV produce any pro-inflammatory responses and its biocompatibility in vivo is studied. The biodistribution of MSV is followed using longitudinal in vivo imaging and organ accumulation is assessed using quantitative elemental and fluorescent techniques. Finally, a thorough pathological analysis of collected tissues demonstrates a mild transient systemic response in the liver that dissipates upon the clearance of particles. It is proposed that future endeavors aimed at understanding the toxicology of naked drug carriers should be designed to address their impact using in vitro and in vivo short- and long-term evaluations of systemic response.

UBE4B levels are correlated with clinical outcomes in neuroblastoma patients and with altered neuroblastoma cell proliferation and sensitivity to epidermal growth factor receptor inhibitors

The UBE4B gene, which is located on chromosome 1p36, encodes a ubiquitin ligase that interacts with hepatocyte growth factor‐regulated tyrosine kinase substrate (Hrs), a protein involved in epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. The authors analyzed the roles of UBE4B in the outcomes of patients with neuroblastoma and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition.

Etoposide-loaded immunoliposomes as active targeting agents for GD2-positive malignancies

Systemic chemotherapeutics remain the standard of care for most malignancies even though they frequently suffer from narrow therapeutic index, poor serum solubility, and off-target effects. In this study, we have encapsulated etoposide, a topoisomerase inhibitor effective against a wide range of cancers, in surface-modified liposomes decorated with anti-GD2 antibodies. We characterized the properties of the liposomes using a variety of methods including dynamic light scattering, electron microscopy, and Fourier transformed infrared spectroscopy. We examined whether these immunoliposomes were able to target cell lines expressing varying levels of surface GD2 and affect cellular proliferation. Anti-GD2 liposomes were generally targeted in a manner that correlated with GD2 expression and inhibited proliferation in cell lines to which they were efficiently targeted. The mechanism by which the immunoliposomes entered targeted cells appeared to be via clathrin-dependent uptake as demonstrated using flow cytometry and confocal microscopy. These studies suggest that anti-GD2-targeted, etoposide-loaded liposomes represent a potential strategy for more effective delivery of anti-cancer drugs that could be used for GD2 positive tumors.

Multistage porous silicon for cancer therapy

Abstract: Advances in biomedical engineering have paved the way for medical innovation and expansion. Many diseases now have hope of a cure through technology brought to reality by the vision and creativity of basic researchers, translational scientists, and doctors. Cancer, in its various manifestations, has plagued the health of millions of people around the world, but still lacks effective therapeutic treatments. By exploiting aberrant native vasculature and unique tissue markers, it is possible today to target the delivery of a given drug to the disease site. In many instances, the body’s natural barriers, and those constructed in the malignant microenvironment, still pose an insurmountable obstacle for the accumulation of efficacious drug levels at the tumor. The nanoporous silicon technology developed by our team in the past 10 years has offered a new and exciting tool for the delivery of drugs. A new paradigm of therapeutics, named multistage vectors, has emerged, with the ability to preferentially target tumors while protecting and delivering payload to the site of action. The boundaries of the utility of such a system are not limited to cancer but hold the potential to extend to all avenues of medicine. This chapter describes the principles of tumorigenesis and the biological barriers as they pertain to the uses and functions of multistage mesoporous silicon. We will discuss the current state of the art in the fabrication, modification, and assembly processes, and provide an overview of the application of this innovative technology in the field of cancer therapy.

UBE4B Levels Are Correlated with Clinical Outcomes in Neuroblastoma Patients and with Altered Neuroblastoma Cell Proliferation and Sensitivity to EGFR Inhibitors

The UBE4B gene, which is located on chromosome 1p36, encodes a ubiquitin ligase that interacts with hepatocyte growth factor‐regulated tyrosine kinase substrate (Hrs), a protein involved in epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. The authors analyzed the roles of UBE4B in the outcomes of patients with neuroblastoma and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition.

Abstract 4586: The Leukosome: A biomimetic liposome for the targeting of inflamed tumor vasculature

The development of targeted cancer treatments with increased therapeutic efficacy is still a major challenge in drug delivery. To date, nanoscale platforms are able to extend their circulation time and accumulate in the tumor through surface functionalization with polyethylene glycol and with antibodies, peptides or ligands directed against tumor biomarkers, respectively. Despite these modifications, the mononuclear phagocytic system efficiently clears these particles from circulation while opsonization proteins prevent the proper recognition between targeting ligands and target biomarkers. Additionally, most cancers are characterized by strong inflammation and increased affinity for circulating leukocytes. The surface of the leukocyte is enriched with transmembrane proteins that determine self-tolerance, adhesion, and negotiation of the inflamed vascular barrier. As result, leukocytes can efficiently recognize and infiltrate the tumor tissues. The Leukosome is a liposomal formulation based on leukocyte membranes able to provide biocompatibility, self-tolerance and targeting. The Leukosome was enriched with up to 82 different leukocyte membrane proteins in their intact native, active configuration with the appropriate post-translational modification and orientation. Among them, CD45 favored extended circulation time and avoided unspecific clearance, while Leukocyte Associated Function-1 facilitated the targeting to and permeability of the tumor inflamed vasculature. The Leukosome retained loading capabilities similar to current liposomal formulations but sustained the release of the chemotherapeutic drug for twice as long. The physical (size, surface charge and polydispersity index), chemical (surface composition and modification, loading and release kinetics), biochemical (protein content and stability), and biological (inhibition of particle clearance, tumor targeting, effect on the vascular barrier function) properties of the Leukosomes confirmed our ability to mimic the biological features and functions of leukocytes. Compared to unmodified liposomes, Leukosomes showed 5-fold increase in circulation time, 50-fold reduction of liver accumulation and 70-fold accumulation of the payload in breast, pancreatic and melanoma models in mouse. We believe this platform will provide a superior tool for the targeting and personalization of therapeutic intervention in cancer. Citation Format: Roberto Molinaro, Alessandro Parodi, Nima Taghipour, Brandon Brown, Dickson Kirui, Michael Evangelopoulos, Francesca Taraballi, Claudia Corbo, Ennio Tasciotti. The Leukosome: A biomimetic liposome for the targeting of inflamed tumor vasculature. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4586. doi:10.1158/1538-7445.AM2014-4586

UBE4B levels are correlated with clinical outcomes in neuroblastoma patients and with altered neuroblastoma cell proliferation and sensitivity to epidermal growth factor receptor inhibitors: UBE4B in Neuroblastoma

The UBE4B gene, which is located on chromosome 1p36, encodes a ubiquitin ligase that interacts with hepatocyte growth factor‐regulated tyrosine kinase substrate (Hrs), a protein involved in epidermal growth factor receptor (EGFR) trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. The authors analyzed the roles of UBE4B in the outcomes of patients with neuroblastoma and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition.