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Background: Exosome-like nanovesicles are biological nanostructures mediating cell-tocell communication and capable to load selected cargos also in the interaction among different species., Objective: We aimed to explore the content of exosome-like nanovesicles derived from Citrus limon L. and to analyze the effects of their uptake on human cells., Method: We isolated exosome-like nanovesicles from Citrus limon L. juice (EXO-CLs) by differential centrifugation. EXO-CLs were analyzed for short RNA content by advanced sequencing technologies, and for ascorbic acid (vitamin C) and citrate content by enzymatic assays. EXO-CLs anti-oxidant and pro-differentiative potential was evaluated in vitro on mesenchymal stromal cells (MSC), a common tool for regenerative strategies for several human tissues., Results: We showed that EXO-CLs carry detectable amounts of citrate and vitamin C and, although it was not possible to identify specific miRNAs, we detected short RNA sequences (20-30 bp) with unknown functions and with different distribution size in respect to whole Citrus limon L. juice. In vitro, EXO-CLs were uptaken by MSC and had a significant protective effect against oxidative stress. Furthermore, regarding the potential benefit for human bone health, we found that EXO-CLs modulate MSC differentiation versus the osteogenic lineage., Conclusion: We demonstrated that incubation with EXO-CLs exert antioxidant activity in human cells. This is most likely due to the direct delivery and uptake of micronutrients by human cells that are well preserved inside the nanovesicle membrane, including the unstable vitamin C. Based on our results, we speculate that fruit-derived nanovesicles have the potential to mediate interspecies influence after food intake., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Drug resistance and therapeutic failure are important causes of disease relapse and progression and may be considered as major obstacles preventing cure of cancer patients. Tumors use a large number of molecular, biochemical and cellular mechanisms to evade chemotherapy and targeted therapy. Important determinants of drug efficacy are the intrinsic pharmacological characteristics of drugs which may be largely affected by the tumor physiology. One feature of solid tumors is the acidic extracellular pH, resulting from metabolic shift and increased metabolic rates combined with low tissue perfusion due to defective vasculature. Besides its role in tumor pathobiology promoting tumor growth and metastasis, the acidic tumor environment creates a chemical barrier for many anticancer drugs, thus limiting their activity. The content of this review will be focused on the pathobiology of tumor acidosis and on its role in therapeutic resistance., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Acridine orange (AO) is an antimalarial drug that accumulates into acidic cellular compartments. Lysosomes are quite acidic in cancer cells, and on this basis we have demonstrated that photoactivated AO is selectively toxic in sarcomas. However, photodynamic therapy is only locally effective, and cannot be used to eradicate systemic residual disease. In this study, we have evaluated the activity of non-photoactivated AO on sensitive and chemoresistant osteosarcoma (OS) cells to be considered for the systemic delivery. Since lysosomes are even more acidic in chemoresistant cells (MDR), we found that AO accumulation was significantly higher in the lysosomes of MDR in respect to parental cells, and in both cell types, therapeutic doses of AO significantly inhibited cell growth. However, the level of growth inhibition was inversely related to the level of lysosomal uptake of AO, suggesting that the main target of this agent is indeed extralysosomal. A significant reduction of intracellular ATP content and of the expression of mitochondrial complex III suggests a mitochondrial targeting. Notably, MDR cells showed a lower mitochondrial activity. Finally, the combined treatment of AO with the anticancer agent doxorubicin (DXR) significantly increased chemotoxicity by promoting DXR mitochondrial targeting, as revealed by the further reduction in ATP intracellular content. In conclusion, AO is able to effectively target both sensitive and resistant OS cells through mitotoxicity.

Bone metastases contribute to morbidity in patients with common cancers, and conventional therapy provides only palliation and can induce systemic side effects. The development of nanostructured delivery systems that combine carriers with bone-targeting molecules can potentially overcome the drawbacks presented by conventional approaches. We have recently developed biodegradable, biocompatible nanoparticles (NP) made of a conjugate between poly (D,L-lactide-co-glycolic) acid and alendronate, suitable for systemic administration, and directly targeting the site of tumor-induced osteolysis. Here, we loaded NP with doxorubicin (DXR), and analyzed the in vitro and in vivo activity of the drug encapsulated in the carrier system. After confirming the intracellular uptake of DXR-loaded NP, we evaluated the anti-tumor effects in a panel of human cell lines, representative for primary or metastatic bone tumors, and in an orthotopic mouse model of breast cancer bone metastases. In vitro, both free DXR and DXR-loaded NP, (58-580 ng/mL) determined a significant dose-dependent growth inhibition of all cell lines. Similarly, both DXR-loaded NP and free DXR reduced the incidence of metastases in mice. Unloaded NP were ineffective, although both DXR-loaded and unloaded NP significantly reduced the osteoclast number at the tumor site (P = 0.014, P = 0.040, respectively), possibly as a consequence of alendronate activity. In summary, NP may act effectively as a delivery system of anticancer drugs to the bone, and deserve further evaluation for the treatment of bone tumors.