After intravenous administration, nanoparticles suffer a major drawback in that they are rapidly and massively taken up by the cells of the mononuclear phagocyte system. The mechanisms involved in the opsonization, adhesion, and internalization of biodegradable nanoparticles by the mononuclear phagocyte system are still poorly understood. In this work, the kinetics of blood protein adsorption onto nanoparticles of poly(D,L-lactic acid) prepared by the salting-out technique was investigated. Nanoparticles of 312 nm were incubated for variable periods of time (5-60 min) in human serum and citrated plasma. After incubation, the particles were washed and the proteins detached from them, denatured, and analyzed by two-dimensional polyacrylamide gel electrophoresis. In plasma, the predominant protein was immunoglobulin G (IgG), and the amount adsorbed was not dependent on incubation time. Albumin amounts were high for short incubation periods but decreased as a function of time, whereas apolipoprotein E levels increased significantly as a function of the incubation period. Owing to the possible complement cascade inactivation by addition of citrate to plasma, the kinetics of adsorption was also evaluated in serum. In this medium, adsorption of complement C3 components onto the surface of the nanoparticles was clearly evidenced by spots of increasing intensity and area, reaching levels comparable to those of the omnipresent IgG. This result confirms the important role of complement components in the opsonization process of poly(D,L-lactic acid) particles.

The objective of this work was to investigate the interactions of poly(D,L-lactic acid) nanoparticles prepared by a recently developed salting-out process, with lymphocytes and monocytes isolated from healthy human donors. Nanoparticles were labeled with a hydrophobic fluorescent dye and incubated with lymphocytes and monocytes, and their uptake was followed by flow cytometry in the presence and absence of plasma. Plasma protein adsorption increased nanoparticle uptake by monocytes, whereas a decrease of cellular binding of the nanoparticles to lymphocytes was noted. The cellular uptake for both cell types consisted in a passive adsorption and in an energy-requiring process, because the cells became 2-3 times more fluorescent when the incubation temperature was increased from 4 to 37 degrees C. When nanoparticles were coated with polyethylene glycol 20,000, uptake by monocytes decreased by 43 and 78% in phosphate-buffered saline and plasma, respectively; a similar decrease in nanoparticle uptake was observed for lymphocytes. Two-dimensional gel electrophoresis was performed to identify the plasma opsonins adsorbed onto the nanoparticle surface. Protein mappings for uncoated and polyethylene glycol-coated nanoparticles differed for two spot series. These spots, not yet clearly identified, may represent specific apolipoproteins involved in the metabolism of human lipoproteins, indicating the possible involvement of specific receptors in the uptake of the nanoparticles.

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Two-dimensional (2-D) maps of cytosol and enriched-membrane platelet proteins has allowed the identification of more than 25 spots by three different methods: matching of the platelet gels with other 2-D reference maps, immunoblotting with chemiluminescence detection, and N-terminal sequencing. Different G protein (guanosine triphosphate-binding protein) subunits, cytoskeletal proteins, and proteins common to the human liver, red blood cells and plasma were identified. The two platelet protein maps presented here contribute to the project of identification of human cell and body fluid proteins. They may serve as working tools since platelets are popular models for the study of central nervous system neurotransmitter systems and stimulus-response coupling mechanisms.

Objectives: Two innovative pharmaceutical forms of leuprorelin acetate have been developed as 1-month and 3-month implants for the treatment of advanced hormone-dependent prostate cancer. These products contain active substance dispersed homogeneously in a biodegradable polymer. Here we present the key results from the clinical development of these slow-release implant formulations of leuprorelin. Methods: Two therapeutic studies of the 1-month implant were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Enantone) as the active control; and a single-arm study of the leuprorelin implant. For the 3-month implant, four therapeutic studies were performed: a randomized, controlled study comparing the leuprorelin implant with leuprorelin prolonged-release microspheres (Trenantone) as the active control; a single-arm study of the leuprorelin implant; and two long-term studies with the 3-month implant administered twice, either 12 or 16 weeks apart. A pooled analysis of data from the comparator-controlled and single-arm studies of the 3-month implant was also conducted. The main inclusion criterion for all studies was histologically confirmed advanced prostate cancer, with primary endpoints based around successful testosterone suppression (≤0.5 ng/ml). Results: In the comparator-controlled studies, both implants were as effective as the microspheres for achieving successful testosterone suppression and normalization of prostate-specific antigen (PSA) levels. Data from the single-arm and long-term studies were consistent with those from the comparator-controlled studies. In the pooled analysis, significantly more patients treated with the 3-month implant achieved successful testosterone suppression compared with the comparator ( p ≤ 0.01). The safety profile of the implants in the comparator-controlled studies was similar to that of the prolonged-release microsphere formulation, and consistent with that of the luteinizing hormone-releasing hormone agonist class. Conclusions: The innovative 1-month and 3-month implants of leuprorelin acetate are at least as effective as leuprorelin acetate prolonged-release microspheres for achieving successful testosterone suppression and normalization of PSA in men with advanced hormone-dependent prostate cancer, with a comparable safety profile.

These results confirm the efficacy, tolerability, and ease of use of the leuprorelin implants among a large population of men with advanced, hormone-dependent prostate cancer treated in a clinical practice setting.

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Glycoprotein modifications in the glycan moiety can occur in diseases such as cancers, inflammatory processes and alcoholism. We combined high-resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) with lectin affinoblotting in order to establish the normal human plasma glycoprotein map. Human plasma proteins were separated by mini 2-D PAGE (7 x 9 cm), transferred onto polyvinylidene difluoride membranes and incubated with biotinylated lectins. We focused our study on lectins binding sialic acid and galactose residues. Known plasma glycoproteins such as alpha 1-antitrypsin, alpha 1-antichymotrypsin, alpha 2-HS glycoprotein, alpha 1-acid glycoprotein, haptoglobin beta-chain and transferrin were easily detected in ng amounts. This protocol was adequate to establish a normal plasma glycoprotein map and will allow the study of glycoproteins in diseases.