Targeted delivery of oligomannose-coated liposome to the omental micrometastasis by peritoneal macrophages from patients with gastric cancer.

We recently developed a novel drug delivery system (DDS) using oligomannose-coated liposomes (OMLs), which are effectively taken up by mouse peritoneal macrophages to carry anticancer drugs to omental milky spots known as initial metastatic sites in the peritoneal cavity in mice. However, the feasibility of the clinical application of this DDS to gastric cancer patients remains essentially unknown. In the present study, we investigated whether human peripheral blood monocytes (PBMs) and human peritoneal macrophages (PEMs) could successfully uptake OMLs and deliver them to the micrometastatic foci in the mouse omentum and resected omentum from cancer patients ex vivo. When OMLs were incubated with the PBMs from four healthy volunteers in vitro, an average 88% of CD14-positive PBMs, most of which also express CD206, took up OMLs, and this uptake was significantly inhibited by alpha-methylmannoside. In the experiment using PEMs obtained from peritoneal washes of five gastric cancer patients, the average uptake rate (63%) of OML by CD14-positive PEMs was somewhat lower than that of PBMs, but in three advanced gastric cancer patients the uptake rate of OMLs was 76% which was comparable to that of mouse PEMs. Oligomannose-coated liposome (OML)-incorporated PBMs and PEMs were successfully accumulated at the micrometastatic foci at the omentum formed after intraperitoneal injection of GFP-tagged gastric cancer cells into mice. Furthermore, OML-incorporated PBMs substantially accumulated to tumor foci in the surgically resected human omentum ex vivo. These results suggest that OMLs using human monocytes/macrophages as a cellular vehicle have the potential to target peritoneal micrometastasis in the omentum of gastric cancer patients.

Sharp pH-responsive mannose prodrug polypeptide nanoparticles encapsulating a photosensitizer for enhanced near infrared imaging-guided photodynamic therapy.

Mannose has been reported as a novel drug to kill cancer cells. The prodrug of mannose will promote its targeted delivery and enrichment at the tumor site and cancer cells. Here, a pH-sensitive polypeptide copolymer with a tertiary amine group has been prepared and a mannose molecule was conjugated to the polymer through the formation of a Schiff base. At the same time, an iodinated boron dipyrromethene (BDPI) photosensitizer with high singlet oxygen generation efficacy and near infrared (NIR) fluorescence was encapsulated by the nanoparticles, which makes it a potential pH-sensitive NIR imaging-guided chemotherapy/PDT agent. In vitro and in vivo studies reveal that in a tumor acidic environment, the protonation of the tertiary amine group destroyed the nanostructure of the nanoparticles, resulting in increased BDPI release. Meanwhile, the bond cleavage of the Schiff base led to the release of conjugated mannose and synergistic inhibition of tumor cell growth with the PDT effect was realized. The combination of these two kinds of tumor suppression effects and photodynamic therapy made this pH-sensitive polypeptide delivery system show great potential for further cancer therapy.

Linear biocompatible glyco-polyamidoamines as dual action mode virus infection inhibitors with potential as broad-spectrum microbicides for sexually transmitted diseases.

The initial steps of viral infections are mediated by interactions between viral proteins and cellular receptors. Blocking the latter with high-affinity ligands may inhibit infection. DC-SIGN, a C-type lectin receptor expressed by immature dendritic cells and macrophages, mediates human immunodeficiency virus (HIV) infection by recognizing mannose clusters on the HIV-1 gp120 envelope glycoprotein. Mannosylated glycodendrimers act as HIV entry inhibitors thanks to their ability to block this receptor. Previously, an amphoteric, but prevailingly cationic polyamidoamine named AGMA1 proved effective as infection inhibitor for several heparan sulfate proteoglycan-dependent viruses, such as human papilloma virus HPV-16 and herpes simplex virus HSV-2. An amphoteric, but prevailingly anionic PAA named ISA23 proved inactive. It was speculated that the substitution of mannosylated units for a limited percentage of AGMA1 repeating units, while imparting anti-HIV activity, would preserve the fundamentals of its HPV-16 and HSV-2 infection inhibitory activity. In this work, four biocompatible linear PAAs carrying different amounts of mannosyl-triazolyl pendants, Man-ISA7, Man-ISA14, Man-AGMA6.5 and Man-AGMA14.5, were prepared by reaction of 2-(azidoethyl)-α-D-mannopyranoside and differently propargyl-substituted AGMA1 and ISA23. All mannosylated PAAs inhibited HIV infection. Both Man-AGMA6.5 and Man-AGMA14.5 maintained the HPV-16 and HSV-2 activity of the parent polymer, proving broad-spectrum, dual action mode virus infection inhibitors.

Two-photon excitation of porphyrin-functionalized porous silicon nanoparticles for photodynamic therapy.

Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect.

Oligomannose-coated liposome as a novel adjuvant for the induction of cellular immune responses to control disease status.

Professional phagocytic cells, such as dendritic cells, are mainly responsible for phagocytosis, antigen presentation, and cytokine secretion, which induce subsequent activation of T cell-mediated immunity. Thus, strategies that deliver antigens and stimulatory signals to the cells have significant implications for vaccine design. In this paper, we summarize the potential for liposomes coated with the neoglycolipids containing oligomannose residues (OMLs) as a novel adjuvant for induction of Th1 immune responses and CTLs specific for the encased antigen. OMLs preferentially take up peripheral phagocytic cells. In response to OML uptake, the cells secrete IL-12 selectively, enhance the expression of costimulatory molecules, and migrate into lymphoid tissues from peripheral tissues. OMLs also have the ability to deliver encapsulated protein antigens to the MHC class I and class II pathways to generate antigen-specific CTLs and Th1 cells, respectively, and lipid antigen to CD1d to activate NKT cells. Since administration of OML-based vaccines can eliminate an established tumor, inhibit elevation of the serum IgE level, and prevent progression of protozoan infections in several murine, human, and bovine models, OML-based vaccines have revealed their potential for clinical use in vaccination for a variety of diseases in which CTLs and/or Th1 cells act as effector cells.