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PubMed1994

Colonic absorption and bioavailability of the pentapeptide metkephamid in the rat.

The concept of delivering systemically active peptide drugs to the colon in order to improve their oral absorption requires reasonable peptide permeability of the large intestinal wall and stability against the activity of the colonic microflora. In addition, the role of hepatic extraction needs to be addressed. In this study the absorption of the pentapeptide metkephamid following single pass perfusion of rat ascending colon was investigated by monitoring its disappearance from the large intestine and simultaneous appearance in the portal vein, the hepatic vein and the aorta. In addition its stability against colonic microflora was tested in vitro using pig caecal contents. Metkephamid was absorbed from the large intestine and appeared in the blood circulation; peptide concentrations in the portal vein increased over-proportionally with increasing perfusate concentrations (0.1-4.6 mmol/L) from 0.19 microgram/mL +/- 0.12 (SD, n = 7) to 31.6 micrograms/mL + 20.65 (SD, n = 4), respectively, and thus suggesting a saturable transport or metabolism. Concentrations in the hepatic vein were significantly lower than in the portal vein, hepatic extraction ratios were 0.35 +/- 0.14, 0.61 +/- 0.18 and 0.62 +/- 0.28 (SD, n = 4) for 0.1, 0.5 and 1.0 mM metkephamid perfusate concentrations, respectively. In the anaerobic colon metabolism model the degradation half-life of the peptide was 14.9 hours, thus, indicating relative stability in the bacterial environment of the colon. The results of the present study encourage further investigations on colonic delivery of peptide drugs.

Animals↗
PubMed1992

Poly (lactic/glycolic acid) microspheres containing antigen as a novel and potential agent of immunotherapy for allergic disorders.

In order to establish a safer and simpler antigen administration method in immunotherapy, we prepared biodegradable microspheres containing antigen and evaluated its safety and efficacy using guinea pigs. Poly (lactic/glycolic acid); (LGA) microspheres containing ovalbumin (OA) were fabricated by solvent evaporation. Over 70% of the OA was released from the microspheres within 3 days, and release was completed within 14 days in vivo. The local tissue reactions to the OA-LGA microspheres were apparently weaker than those to OA-alum. Repeated injections of high dose OA-LGA microspheres to OA-sensitized guinea pigs (high-LGA group) for 8 weeks at intervals of 2 weeks elicited an excellent therapeutic effect, i.e. a significant increase in the threshold value of antigen inhalation test, with a significant increase in IgG2 blocking antibody. The therapeutic efficacy of the high-LGA group was comparable to the conventional immunotherapy model (conventional group) and was superior to the antigen-alum model (alum group). We concluded that administration of antigen-LGA microspheres could become a new immunotherapeutic method for allergic disorders, being safer and requiring a lower frequency of antigen injections than the conventional method.

Animals↗
PubMed1997

In vitro degradation of pH-sensitive hydrogels containing aromatic azo bonds.

Biodegradable and pH-sensitive hydrogels containing azoaromatic moieties were synthesized from the same polymeric precursors by two synthetic methods, namely a polymer-polymer reaction and cross-linking of polymeric precursors. The effect of the synthetic route employed and the detailed network structure on in vitro degradation of hydrogels was studied. Regardless of the synthetic method used, two patterns of degradation were observed. Hydrogels with lower cross-linking density underwent a surface erosion process and degraded at a faster rate. Hydrogels with higher cross-linking densities degraded at a slower rate by a process where a colourless degradation front moved inward to the yellow core. It appears that hydrogels synthesized by a polymer-polymer reaction degraded at a slightly faster rate than their analogues synthesized by cross-linking of polymeric precursors. The degradation rate of a hydrogel was compared with those of a linear azopolymer and a low-molecular-weight azosubstrate (methyl orange) respectively. The degradation rates were in the order of hydrogel < linear azopolymer < low-molecular-weight azosubstrate.

Animals↗
PubMed2006

In vivo targeting of dendritic cells in lymph nodes with poly(propylene sulfide) nanoparticles.

Delivery of biodegradable nanoparticles to antigen-presenting cells (APCs), specifically dendritic cells (DCs), has potential for immunotherapy. This study investigates the delivery of 20, 45, and 100nm diameter poly(ethylene glycol)-stabilized poly(propylene sulfide) (PPS) nanoparticles to DCs in the lymph nodes. These nanoparticles consist of a cross-linked rubbery core of PPS surrounded by a hydrophilic corona of poly(ethylene glycol). The PPS domain is capable of carrying hydrophobic drugs and degrades within oxidative environments. 20 nm particles were most readily taken up into lymphatics following interstitial injection, while both 20 and 45nm nanoparticles showed significant retention in lymph nodes, displaying a consistent and strong presence at 24, 72, 96 and 120h post-injection. Nanoparticles were internalized by up to 40-50% of lymph node DCs (and APCs) without the use of a targeting ligand, and the site of internalization was in the lymph nodes rather than at the injection site. Finally, an increase in nanoparticle-containing DCs (and other APCs) was seen at 96h vs. 24h, suggesting an infiltration of these cells to lymph nodes. Thus, PPS nanoparticles of 20-45nm have the potential for immunotherapeutic applications that specifically target DCs in lymph nodes.

Animals↗
PubMed2005

DNA delivery from hyaluronic acid-collagen hydrogels via a substrate-mediated approach.

Efficient and controlled gene delivery from biodegradable materials can be employed to stimulate cellular processes that lead to tissue regeneration. In this report, a substrate-mediated approach was developed to deliver DNA from hyaluronic acid-collagen hydrogels. The hydrogels were formed by crosslinking HA with poly(ethylene glycol) diglycidyl ether. Poly(ethylene imine)(PEI)/DNA complexes were immobilized to the substrate using either biotin/neutravidin or non-specific adsorption. Complexes were formed in the presence or absence of salt to regulate complex size, and resulted in complexes with z-average diameters of 1221.7 +/- 152.3 and 139.4 +/- 1.3 nm, respectively. During 48-h incubation in PBS or hyaluronidase, DNA was released slowly from the hydrogel substrate (<30% of immobilized DNA), which was enhanced by incubation with conditioned media (approximately 50% of immobilized DNA). Transgene expression mediated by immobilized, large diameter complexes was 3 to 7-fold greater than for small diameter complexes. However, the percentage of cells expressing the transgene was greater for small diameter complexes (48.7%) than for large diameter complexes (22.3%). Spatially controlled gene transfer was achieved by topographically patterning the hydrogel to pattern cell adhesion. Biomaterial-based gene delivery can be applicable to numerous tissue engineering applications, or as a tool to examine tissue formation.

Absorbable Implants↗
PubMed2004

Apotransferrin is internalized and distributed in the same way as holotransferrin in K562 cells.

Transferrin (Tf), a naturally existing protein, has received considerable attention in the area of drug targeting since it is biodegradable, non-toxic, and non-immunogenic. The efficient cellular uptake of Tf shows it has potential in the delivery of anti-cancer drugs, proteins, and therapeutic genes into proliferating malignant cells that overexpress transferrin receptor (TfR). In human serum, about 30% of Tf exists in the iron-saturated form (Fe(2)-Tf) and the remainder exists as apotransferrin (apo-Tf). Understanding the uptake of apo-Tf by cells will provide key insights into studies on Tf-mediated drug delivery. In the present study, we investigated visually the transport of apo-Tf into K562 cells and its intracellular localization by laser-scanning confocal microscopy (LSCM) and flow cytometry analysis (FCA). It was found that, like Fe(2)-Tf, apo-Tf can be taken up into the cells. The process is time- and temperature-dependent, competitively inhibited by Fe(2)-Tf, and significantly abolished by pronase pretreatment. Visual evidence showed that the transport of apo-Tf into K562 cells is a TfR-mediated process. Furthermore, the investigations using optical-slicing technique demonstrated that the distribution of apo-Tf is similar to that of Fe(2)-Tf, both appearing in the perinuclear region in ball-in-bowl shape.

Apoproteins↗
PubMed2005

Biodegradable cationic PEG-PEI-PBLG hyperbranched block copolymer: synthesis and micelle characterization.

A novel amphiphilic biodegradable cationic hyperbranched poly(ethylene glycol)-polyethylenimine-poly(gamma-benzyl L-glutamate) (PEG-PEI-PBLG) block copolymer was successfully synthesized by ring-opening polymerization (ROP) of N-carboxyanhydride of gamma-benzyl-L-glutamate (BLG-NCA) with PEG-PEI as a macroinitiator. PEG-PEI was firstly prepared by coupling of PEG and PEI using hexamethylene diisocyanate (HMDI). The structural properties of PEG-PEI-PBLG copolymers were confirmed by 1H NMR and GPC. The copolymers were found to be self-assembled in water with critical micelle concentration (CMC) in the range of 0.00368-0.0125 g/l and high hydrophobic micelle core. The micelle size and CMC obviously depended on the hydrophobic block content in the copolymer and the ionic state of the PEI block. The CMC decreased with the increase in the PBLG block content. The decrease of micelle size and the increase of CMC simultaneously occurred with the protonated degree of PEI block by addition of HCl solution. ESEM and Gel retardation assay showed that the cationic micelles had ability to encapsulate plasmid DNA. The copolymer has potential medical applications in drug and gene delivery.

Absorbable Implants↗
PubMed2006

In vivo performance of implantable biodegradable preparations delivering Paclitaxel and Etanidazole for the treatment of glioma.

Drug-releasing implants delivering chemotherapeutic and radio-sensitizing agents are beginning to play a major role in the post-surgical eradication of residual glioma in the brain. Benefits from early arresting of tumor growth and tumor recovery dynamics stress the impact of drug release profiles of the implants on the efficacy of the treatment. This paper examines responses of BALB/c nude mice, bearing C6 glioma tumors subcutaneously, to treatments by PLGA microspheres, microparticles and discs-delivering Paclitaxel and Etanidazole. The experimental results are used to correlate the efficacy of treatment to in vitro release profiles from the various formulations. Our study demonstrates that radio-sensitizing effects during irradiation could be achieved by double burst profiles from Etanidazole-loaded discs, when compared to controls 17 days after implantation despite the short half-life of Etanidazole (1.4h) in vivo. These results also showed inhibited tumor growth on tumor volumes of 59%, 65% and 70% over the blank placebo groups after 21 days of tumor growth for spray-dried microspheres, electrohydrodynamic atomization microparticles and spray-dried discs, respectively.

Animals↗
PubMed2004

Pain control via opioid analgesic-local anesthetic loaded IPNs.

Relief of chronic pain is an important clinical problem requiring special care and approaches. The present study was designed for the construction of a controlled release system for local application of analgesics (hydromorphone (HM), morphine (M), and codeine (C)) and a local anesthetic, bupivacaine (BP). An interpenetrating network (IPN) drug release system was prepared by using a biocompatible, biodegradable copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and another biocompatible but synthetic, nondegradable polymer, poly (2- hydroxyethyl methacrylate), (PHEMA). In situ release kinetics of the IPN system was first order for BP but could not be fitted to any known equation for the other drugs. Complete release from the IPNs occurred within a considerably short time (24 h for 80 % of the drugs) most probably due to the significant hydrophilicity of PHEMA. In order to slow down the release rate these IPNs were coated with PHBV. Release from these coated IPNs (cIPN) resulted in rates that could be described by Higuchi's equations. In vivo measurement of antinociceptive efficacy was carried out in rats with tail flick and paw-withdrawal tests after inducing chronic pain created by sciatic nerve ligation at the right side. Control groups received placebo implants. In vivo studies showed potent, prolonged (2-3 days) antinociception at the site of injury (right paw) for strong opioids (HM and M) and about 2 days for the weak opioid (C) and local anesthetic (BP). In all cases the release rate was found to be as important as the antinociceptive potency. The weakest opioid analgesic of those evaluated (C) had a higher first day antinociception than its stronger counterpart M, probably due to its higher initial concentration that was expected from its faster release rate in the in situ experiments.

Analgesics, Opioid↗
PubMed1999

Modification of release rates of cyclosporin A from polyl(L-lactic acid) microspheres by fatty acid esters and in-vivo evaluation of the microspheres.

Biodegradable microspheres containing cyclosporin A (CyA, cyclosporine) were prepared using poly(L-lactic acid) (PLA) and poly(lactide-co-glycolide)(PLGA) by a solvent evaporation method. CyA was efficiently entrapped in PLA, PLGA(50/50) and PLGA(75/25) microspheres in a range of 81-85%. CyA released constantly from PLA microspheres without any lag time, whereas the drug from PLGA(50/50) and PLGA(75/25) microspheres was released after lag time of about 1 and 3 weeks, respectively. Addition of fatty acid esters enhanced the release rates of CyA from PLA microspheres. In-vivo study was performed using rats with adjuvant-induced arthritis. PLA microspheres with ethyl myristate sustained high blood levels of CyA compared with the microspheres with no additives over 4 weeks. In addition, the PLA microspheres improved the symptoms such as the decrease in body weight and the increase in paw swelling occurred by adjuvant-induced arthritis in rats. Consequently, the release rate of CyA from PLA microspheres can be improved by adding fatty acid esters and PLA microspheres with fatty acid esters seem to be a useful dosage form for autoimmune disease therapy.

Animals↗
PubMed2006

A novel bioerodible deep scleral lamellar cyclosporine implant for uveitis.

PURPOSE: To determine the feasibility, safety, and effectiveness of an episcleral or deep scleral lamellar sustained release cyclosporine (CsA) device in a naturally occurring animal model of uveitis. METHODS: A two-compartment perfusion chamber was used to assess in vitro human and equine scleral permeability of fluorescein, dexamethasone-fluorescein, or CsA. A biodegradable, matrix-reservoir CsA implant was designed, and release rates of CsA were determined in vitro. Tissue CsA levels were measured in eyes with the implant. Horses with equine recurrent uveitis (ERU) received episcleral or deep scleral lamellar CsA implants and were monitored for up to 3 years. RESULTS: Dexamethasone-fluorescein and CsA penetrated the in vitro equine sclera poorly; however, low but detectable levels of CsA were detected intraocularly in vivo. The implant placed episclerally failed to control inflammatory episodes in ERU. CsA implants placed in the deep sclera adjacent to the suprachoroidal space resulted in high levels of CsA in most ocular tissues. In clinical equine patients with ERU, frequency of uveitic flare-ups was significantly decreased after implantation of a deep scleral lamellar CsA implant. CONCLUSIONS: Diffusion of CsA across the sclera from the episcleral space was not a feasible method of drug delivery to the equine eye. However, placing a deep scleral lamellar CsA implant adjacent to the suprachoroidal space was effective in achieving therapeutic ocular drug concentrations and controlling uveitis in horses with ERU.

Absorbable Implants↗
PubMed2000

The controlled release of a drug from biodegradable chitosan gel beads.

Chitosan (CS) forms a gel in solutions with a pH above 12, and the gelation occurs at pH of about 9 in 10% amino acid solutions. In this paper, we investigated the enzymatic degradation and the drug release profile of this novel CS gel beads. The degradability of the CS gel beads was affected by the CS properties, e.g. the degree of deacetylation. The release of prednisolone (PS), as a model drug, from the CS gel beads was sustained significantly compared with the gel prepared with NaOH only. However, the release was not able to be sustained by the increment of NaOH concentration in the solution employed for the preparation of CS gel beads. We also investigated the control of drug release from CS gel beads by application of a complex formed between chondroitin sulfate (Cho) and CS. The release of PS from the CS gel beads treated with Cho was prolonged, and the release pattern was not affected by the treatment time. The time to 50% drug release was about 5 min with PS powder, about 200 min in CS gel beads with 10% glycine (Gly) (pH 9.0), and about 330 min in the CS gel beads with 10% Gly (pH 9.0) treated with Cho. Thus CS gel beads appear promising as a vehicle for sustained drug delivery, and the degradation of CS gel beads may be controlled by the degree of deacetylation of CS.

Chitin↗
PubMed2003

Ligand-specific targeting of microspheres to phagocytes by surface modification with poly(L-lysine)-grafted poly(ethylene glycol) conjugate.

PURPOSE: The purpose of this study was to demonstrate specific receptor-mediated targeting of phagocytes by functional surface coatings of microparticles, shielding from nonspecific phagocytosis and allowing ligand-specific interactions via molecular recognition. METHODS: Coatings of the comb polymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) were investigated for potential to inhibit 1) nonspecific spreading of human blood-derived macrophages (MOs) and dendritic cells (DCs) on glass and 2) nonspecific phagocytosis of PLL-g-PEG-coated, carboxylated polystyrene (PS) or biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres. Coating was performed by adsorption of positively charged PLL-g-PEG on negatively charged microparticles or plasma-cleaned glass through electrostatic interaction. The feasibility of ligand-specific interactions was tested with a model ligand, RGD, conjugated to PEG chains of PLL-g-PEG to form PLL-g-PEG-RGD and compared with inactive ligand conjugate, PLL-g-PEG-RDG. RESULTS: Coatings with PLL-g-PEG largely impaired the adherence and spreading of MOs and DCs on glass. The repellent character of PLL-g-PEG coatings drastically reduced phagocytosis of coated PS and PLGA microparticles to 10% in presence of serum. With both MOs and DCs, we observed ligand-specific interactions with PLL-g-PEG-RGD coatings on glass and PS and PLGA microspheres. Ligand specificity was abolished when using inactive ligand conjugate PLL-g-PEG-RDG, whereas repellency of coating was maintained. CONCLUSIONS: Coatings of PLL-g-PEG-ligand conjugates provide a novel technology for ligand specific targeting of microspheres to MOs and DCs while reducing nonspecific phagocytosis.

Cells, Cultured↗
PubMed1997

Utilization of an amorphous form of a water-soluble GPIIb/IIIa antagonist for controlled release from biodegradable microspheres.

PURPOSE: We prepared injectable microspheres for controlled release of TAK-029, a water-soluble GPIIb/IIIa antagonist and discussed the characteristics of controlled release from microspheres. METHODS: Copoly(dl-lactic/glycolic)acid (PLGA) microspheres were used for controlled release of TAK-029 [4-(4-amidinobenzoylglycyl)-3-methoxycarbonyl-2-oxopiperazine++ +-1-acetic acid]. They were prepared with a solid-in-oil-in-water (S/O/W) emulsion solvent evaporation technique using either a crystalline form or an amorphous form of the drug. RESULTS: An amorphous form of TAK-029 gave more homogeneous S/O dispersion and higher viscosity than its crystalline form when added to dichloromethane solution of PLGA, resulting in a high drug entrapment into microspheres and a well-controlled release of the drug. Additions of sodium chloride into an external aqueous phase and L-arginine into an oil phase also increased entrapment of the drug, and reduced initial burst of the drug from the microspheres. The microspheres demonstrated a desirable plasma level profile in therapeutic range (20-100 ng/ml) for 3 weeks in rats after single subcutaneous injection. CONCLUSIONS: A well-controlled release of TAK-029, a water-soluble neutral drug, with small initial burst was achieved by utilizing its amorphous form as a result of possible interaction with PLGA and L-arginine.

Animals↗
PubMed2003

Biologic activity of nerve growth factor slowly released from microspheres.

Efficient and sustained delivery of neurotrophic factors to the regenerating nerve in biologically active form presents a challenge. Protein delivery in biodegradable microsphere vehicles has been difficult, based on destabilization and breakdown during both the loading and release phases. This study examines the extravasation and stability of Nerve Growth Factor (NGF) in polylactic-co-glycolic acid (PLGA) microspheres, via both ELISA and PC-12 bioassays. PLGA microspheres co-loaded with bovine serum albumin (BSA) and NGF were prepared by a water-in-oil-in-water (W/O/W) technique, using chloroform for the organic phase and 1 percent polyvinyl alcohol (PVA) for the emulsion step. Aliquots of lyophilized microspheres were incubated in double distilled water (dd H2O) at 37 degrees C, and the supernatants assayed over time for NGF activity. ELISA was utilized for quantitative determination of NGF concentration, and a PC-12 cell neurite outgrowth assay assessed biologic activity. Both ELISA and PC-12 assays demonstrated the extravasation of NGF from microspheres. Over time, the predicted concentration of NGF via the two assays differed, suggesting possible preservation of recognizable epitopes for ELISA, but loss of biologic activity. NGF can be stored and released from microspheres. Extravasation studies should include biologically relevant assays for activity.

Animals↗
PubMed2006

Controlled drug release from a novel injectable biodegradable microsphere/scaffold composite based on poly(propylene fumarate).

The ideal biomaterial for the repair of bone defects is expected to have good mechanical properties, be fabricated easily into a desired shape, support cell attachment, allow controlled release of bioactive factors to induce bone formation, and biodegrade into nontoxic products to permit natural bone formation and remodeling. The synthetic polymer poly(propylene fumarate) (PPF) holds great promise as such a biomaterial. In previous work we developed poly(DL-lactic-co-glycolic acid) (PLGA) and PPF microspheres for the controlled delivery of bioactive molecules. This study presents an approach to incorporate these microspheres into an injectable, porous PPF scaffold. Model drug Texas red dextran (TRD) was encapsulated into biodegradable PLGA and PPF microspheres at 2 microg/mg microsphere. Five porous composite formulations were fabricated via a gas foaming technique by combining the injectable PPF paste with the PLGA or PPF microspheres at 100 or 250 mg microsphere per composite formulation, or a control aqueous TRD solution (200 microg per composite). All scaffolds had an interconnected pore network with an average porosity of 64.8 +/- 3.6%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy and confocal microscopy. The composite scaffolds exhibited a sustained release of the model drug for at least 28 days and had minimal burst release during the initial phase of release, as compared to drug release from microspheres alone. The compressive moduli of the scaffolds were between 2.4 and 26.2 MPa after fabrication, and between 14.9 and 62.8 MPa after 28 days in PBS. The scaffolds containing PPF microspheres exhibited a significantly higher initial compressive modulus than those containing PLGA microspheres. Increasing the amount of microspheres in the composites was found to significantly decrease the initial compressive modulus. The novel injectable PPF-based microsphere/scaffold composites developed in this study are promising to serve as vehicles for controlled drug delivery for bone tissue engineering.

Bone Cements↗
PubMedDate not supplied

The stability of insulin in biodegradable microparticles based on blends of lactide polymers and polyethylene glycol.

Insulin-loaded microparticles were produced from blends of poly(ethylene glycol) (PEG) with poly (L-lactide) (PLA) homopolymer and poly (DL-lactide co-glycolide) copolymers (PLG) using a water-in-oil solvent extraction method. The dispersed phase was composed of PLG/PEG or PLA/PEG dissolved in dichloromethane, and the continuous phase was methanol containing 10% PVP. Characteristics, including particle size distribution, insulin loading capacity and efficiencies, in vitro release, degradation and stability, were investigated. The stability of insulin associated with microparticles prepared using PEG and 50:50 PLG and PLA was analysed by HPSEC and quantified by peak area following incubation in PBS at 37 degrees C for up to 1 month. Insulin was successfully entrapped in the PLG/PEG and PLA/PEG microparticles with trapping efficiencies up to 56 and 48%, loading levels 17.8 and 10.6% w/w, and particle sizes 8 and 3 microm, respectively. The insulin-loaded PLG/PEG and PLA/PEG microparticles were capable of controlling the release of insulin over 28 days with in vitro delivery rates of 0.94 and 0.65 microg insulin/mg particles/day in the first 4 days and a steady release with rate of 0.4 and 0.43 microg insulin/mg particles/day over the following 4 weeks, respectively. Extensive degradation of the PLG/PEG microparticles also occurred over 4 weeks, whereas the use of PLA/PEG blends resulted in a stable microparticle morphology and much reduced fragmentation and aggregation of the associated insulin.

Biocompatible Materials↗
PubMed2005

Preparation of protein loaded poly(D,L-lactide-co-glycolide) microparticles for the antigen delivery to dendritic cells using a static micromixer.

The cellular immune response against tumors, viruses, or intracellular bacteria requires adequate antigen delivery to professional phagocytes, their processing and the presentation of antigenic peptides to T-cells. Biodegradable microparticles to enhance antigen phagocytosis and the response of cytotoxic lymphocytes have been proposed. The aim of the present study was to formulate poly(lactide-co-glycolide) (PLGA) microparticles using a w/o/w solvent evaporation procedure in order to obtain suitable vehicles for vaccination. Bovine serum albumin bearing fluorescein isothiocyanate (FITC-BSA) was used as a model antigen. For microparticle preparation a static micromixer was employed. Microparticles of 2-3 microm can be produced with good reproducibility by applying high flow rates at the micromixer. Microparticles with a smooth surface and only one pore were observed using scanning electron microscopy (SEM). Confocal laser scanning microscopy (CLSM) allowed localisation of the FITC-BSA near the surface of the microparticle. Microencapsulation of FITC-BSA did not altered the polymer characteristics, as determined by measuring the glass transition temperature. Additionally we could determine residual methylene chloride, employed as solvent in microparticle preparation, to be less than 1/1000 of the USP and Ph. Eur. limit. The microparticles described herein were able to deliver the model antigen to human dendritic cells (DC).

Antigen-Presenting Cells↗