As an important part of tumor microenvironment, tumor associated macrophages (TAMs) play a vital role in the occurrence, development, invasion, and metastasis of many malignant tumors and can significantly promote the formation of tumor blood vessels and lymphatic vessels, hence TAMs are greatly associated with poor prognosis. The research on nanomedicine has achieved huge progress, and nano-drugs have been widely utilized to treat various diseases through different mechanisms. Therefore, developing nano-drugs that are based on TAMs-associated anti-tumor mechanisms to effectively suppress tumor growth is expected to be a promising research filed. This paper introduces relevant information about TAMs in terms of their origin, and their roles in tumor genesis, development and metastasis. Furthermore, TAMs-related anti-tumor nano-drugs are summarized. Specifically, a wide range of nano-drugs targeting at TAMs are introduced, and categorized according to their therapeutic mechanisms toward tumors. Additionally, various nano delivery platforms using TAMs as cell carriers which aim at inhibiting tumor growth are reviewed. These two parts elucidate that the exploration of nanomedicine is essential to the study on TAMs-related anti-tumor strategies. This review is also intended to provide novel ideas for in-depth investigation on anti-tumor molecular mechanisms and nano-drug delivery systems based on TAMs.

Combinations of chemotherapeutics with small interfering RNA (siRNA) can incorporate the advantages of their different mechanisms to exert a synergetic effect. A safe and effective vehicle for simultaneous delivery of the components to tumor cells is a prerequisite for obtaining the optimum effect. We developed an amphiphilic dendrimer engineered nanocarrier system (ADENS) for co-delivering paclitaxel and siRNA for cancer treatment. This nanocarrier possesses a unique hollow core/shell structure in which siRNA is incorporated in the hydrophilic cavity and large quantities of paclitaxel are stored in the hydrophobic interlayer, while the outer PEG layer serves to prolong the circulation time. Further modification by tumor microenvironment-sensitive polypeptides (TMSP) significantly enhanced the cellular uptake, tumor penetration and tumor accumulation of the ADENS by a tumor microenvironment-triggered mechanism. TMSP-ADENS had prominent therapeutic effects at a relatively low drug dose both in vitro and in vivo. In A375 xenograft mice, TMSP-ADENS/siRNA/PTX showed the highest VEGF mRNA inhibition rate of 73% and suppressed tumor growth and relapse, while Taxol did not show an effect on tumor relapse. The anti-tumor and anti-angiogenic effects were further confirmed in an HT-1080 xenograft tumor model. Our findings, combined with the known biodegradability and tunable physicochemical properties of these polymers, suggest that this TMSP-ADENS can be a robust co-delivery system for cancer combination therapy in the future.

BackgroundAbnormal expression of stromal cells and extracellular matrix in tumor stroma creates a tight barrier, leading to insufficient extravasation and penetration of therapeutic agents. Cancer-associated fibroblasts (CAFs) take on pivotal roles encouraging tumor progression.MethodTo surmount the refractoriness of stroma, we constructed a multi-targeting combined scenario of anti-CAFs agent tranilast and antitumor agent docetaxel micelles (DTX-Ms). Tranilast cut down crosstalk between tumor cells and stromal cells, ameliorated the tumor microenvironment, and enhanced the antiproliferation efficacy of DTX-Ms on cancer cells.ResultsDiverse experiments demonstrated that tranilast enhanced DTX-Ms’ antitumor effect in a two-stage pattern by CAFs ablation, tumor cell migration blocking, and metastasis inhibition. Along with activated CAFs decreasing in vivo, the two-stage therapy succeeded in reducing interstitial fluid pressure, normalizing microvessels, improving micelles penetration and retention, and inhibiting tumor growth and metastasis. Interestingly, tranilast alone failed to inhibit tumor growth in vivo, and it could only be used as an adjuvant medicine together with an antitumor agent.ConclusionOur proposed two-stage therapy offers a promising strategy to enhance antitumor effects by breaking down CAFs barrier and increasing micellar delivery efficiency.

Kaempferol-3-O-rutinoside (K3R) has been proven to have biological activities for the prevention and treatment of central nervous system (CNS) diseases. However, the details of its absorption from the gastrointestinal tract and transport across the blood-brain barrier (BBB) are not clear. Therefore, to provide a basis for its efficacy, we explored its intestinal absorption with Caco-2 monolayer cells, rat orthotopic intestinal perfusion, its transport across a BBB model based on bEnd.3 monolayer cells and its pharmacological effects on PC12 cells in terms of neuropathy. The results indicated that the transport of K3R is concentration dependent; moreover, the apparent permeability coefficient (P app ) of K3R lacked directionality, and the efflux rate after adding P-glycoprotein inhibitor did not show a significant change. K3R was found to be completely absorbed in the intestines of rats, and the absorption process follows the first-order kinetics. K3R can pass through the BBB with passive diffusion. The neuroprotective effects of K3R were related to stabilization of the mitochondrial membrane and a decrease in reactive oxygen species. These results demonstrated that K3R can be absorbed in a relatively moderate ratio in the gastrointestinal tract and transported to the brain. Thus, K3R may be a potent drug for the prevention and treatment of neurodegenerative diseases such as Parkinson's disease.