The transmission and toxicity of polymer-bound doxorubicin-containing exosomes derived from human adenocarcinoma cells.

Background: Exosomes are extracellular vesicles with the ability to encapsulate bioactive molecules, such as therapeutics. This study identified a new exosome mediated route of doxorubicin and poly(N-(2-hydroxypropyl)methacrylamide) (pHPMA)-bound doxorubicin trafficking in the tumor mass. Materials & methods: Exosome loading was achieved via incubation of the therapeutics with an adherent human breast adenocarcinoma cell line and its derived spheroids. Exosomes were characterized using HPLC, nanoparticle tracking analysis (NTA) and western blotting. Results: The therapeutics were successfully loaded into exosomes. Spheroids secreted significantly more exosomes than adherent cells and showed decreased viability after treatment with therapeutic-loaded exosomes, which confirmed successful transmission. Conclusion: To the best of our knowledge, this study provides the first evidence of pHPMA-drug conjugate secretion by extracellular vesicles.

Background: In cancer treatment, low-molecular-weight drugs (e.g., doxorubicin [DOX]) with a broad spectrum of side effects are commonly used. Through their conjugation with hydrophilic polymers ­ N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers ­ for example, most of the side effects can be reduced. These drug­polymer conjugates are delivered via bloodstream into the tumor. This study aimed to identify a new exosome-mediated route of DOX and polyHPMA(pHPMA)­DOX conjugates trafficking inside the tumor mass. Exosomes are small lipid membrane vesicles constitutively released from most of the cell types, including the tumor cells. Exosomes are able to encapsulate low-molecular-weight drugs. Methods: Exosomes were loaded with DOX and pHPMA-DOX in vitro via coincubation with cancer cells. Exosomes were isolated from the conditioned-cultivation medium after their release from cells and characterized (size, numbers, protein marker profiles). Results: The therapeutics were successfully loaded into exosomes and transmitted to the tumor cells. To the best of our knowledge, this is the first evidence of the pHPMA­drug conjugate secretion by exosomes.

Rose Bengal-Modified Upconverting Nanoparticles: Synthesis, Characterization, and Biological Evaluation.

High-quality upconverting NaYF4:Yb3+,Er3+ nanoparticles (UCNPs; 26 nm in diameter) based on lanthanides were synthesized by a high-temperature coprecipitation method. The particles were modified by bisphosphonate-terminated poly(ethylene glycol) (PEG) and Rose Bengal (RB) photosensitizer. The particles were thoroughly characterized using transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, FTIR, and X-ray photoelectron and upconversion luminescence spectroscopy in terms of morphology, hydrodynamic size, composition, and energy transfer to the photosensitizer. Moreover, the singlet oxygen generation from RB-containing UCNPs was investigated using 9,10-diphenylanthracene probe under 980 nm excitation. The cytotoxicity of UCNPs before and after conjugation with RB was evaluated on highly sensitive rat mesenchymal stem cells (rMSCs) and significant differences were found. Correspondingly, consi-derable variations in viability were revealed between the irradiated and non-irradiated rat glioma cell line (C6) exposed to RB-conjugated UCNPs. While the viability of rMSCs was not affected by the presence of UCNPs themselves, the cancer C6 cells were killed after the irradiation at 980 nm due to the reactive oxygen species (ROS) production, thus suggesting the potential of RB-conjugated PEG-modified UCNPs for applications in photodynamic therapy of cancer.

Glycopolymers for Efficient Inhibition of Galectin-3: In Vitro Proof of Efficacy Using Suppression of T Lymphocyte Apoptosis and Tumor Cell Migration.

The development of efficient galectin-3 (Gal-3) inhibitors draws attention in the field of anti-cancer therapy, especially due to the prominent role of extra- and intracellular Gal-3 in vital processes of cancerogenesis, such as immunosuppression, stimulation of tumor cells proliferation, survival, invasion, apoptotic resistance, and metastasis formation and progression. Here, by combining poly-LacNAc (Galß4GlcNAc)-derived oligosaccharides with N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers, we synthesized multivalent glycopolymer inhibitors with a high potential to target extracellular and intracellular Gal-3. The inhibitory capabilities of the best conjugate in the studied series were in the nanomolar range proving the excellent Gal-3 inhibitory potential. Moreover, thorough investigation of the inhibitory effect in the biological conditions showed that the glycopolymers strongly inhibited Gal-3-induced apoptosis of T lymphocytes and suppressed migration and spreading of colorectal, breast, melanoma, and prostate cancer cells. In sum, the strong inhibitory activity toward Gal-3, combined with favorable pharmacokinetics of HPMA copolymers ensuring enhanced tumor accumulation via the enhanced permeability and retention effect, nominate the glycopolymers containing LacdiNAc-LacNAc (GalNAcß4GlcNAcß3Galß4GlcNAc) tetrasaccharide as promising tools for preclinical in anti-cancer therapy evaluation.

γ-Butyrolactone Copolymerization with the Well-Documented Polymer Drug Carrier Poly(ethylene oxide)-block-poly(ε-caprolactone) to Fine-Tune Its Biorelevant Properties.

Polymeric drug carriers exhibit excellent properties that advance drug delivery systems. In particular, carriers based on poly(ethylene oxide)-block-poly(ε-caprolactone) are very useful in pharmacokinetics. In addition to their proven biocompatibility, there are several requirements for the efficacy of the polymeric drug carriers after internalization, e.g., nanoparticle behavior, cellular uptake, the rate of degradation, and cellular localization. The introduction of γ-butyrolactone units into the hydrophobic block enables the tuning of the abovementioned properties over a wide range. In this study, a relatively high content of γ-butyrolactone units with a reasonable yield of ≈60% is achieved by anionic ring-opening copolymerization using 1,5,7-triazabicyclo[4.4.0]dec-5-ene as a very efficient catalyst in the nonpolar environment of toluene with an incorporated γ-butyrolactone content of ≈30%. The content of γ-butyrolactone units can be easily modulated according to the feed ratio of the monomers. This method enables control over the rate of degradation so that when the content of γ-butyrolactone increases, the rate of degradation increases. These findings broaden the application possibilities of polyester-polyether-based nanoparticles for biomedical applications, such as drug delivery systems.