Controlled delivery of taxol from poly(ethylene glycol)-coated poly(lactic acid) microspheres.

The development of injectable microspheres for sustained drug delivery to the arterial wall is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, taxol, in poly(ethylene glycol) (PEG)-coated biodegradable poly(lactic acid) (PLA) microspheres with a mean diameter of 2-6 microm. A solution of taxol and PLA dissolved in an acetone/dichloromethane mixture was poured into an aqueous solution of PEG [or poly(vinyl alcohol) (PVA] with stirring with a high-speed homogenizer for the formation of microspheres. Taxol recovery in PLA-PEG microspheres was higher (61.2 +/- 2.3%) than with PVA-based (41.6 +/- 1.8%) preparations. An analysis by diffuse reflectance infrared Fourier transform spectroscopy revealed that PEG was incorporated well on the PLA microsphere surface. Scanning electron microscopy revealed that the PEG-coated PLA microspheres were spherical in shape and had a smooth surface texture like those of PVA-based preparations. The amount of drug release was much higher initially (25-30%); this was followed by a constant slow-release profile for a 30-day period of study. This PEG-coated PLA microsphere formulation may have potential for the targeted delivery of antiproliferative agents to treat restenosis.     

Changes in cisplatin delivery due to surface-coated poly (lactic acid)-poly(epsilon-caprolactone) microspheres

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Local delivery of agents capable of modulating vascular responses, have the potential to prevent restenosis. However, the development of injectable microspheres for sustained drug delivery to the arterial wall is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, cisplatin, in a series of surface coated biodegradable microspheres composed of poly(lactic acid)poly(caprolactone) blends, with a mean diameter of 2-10 pm. The microspheres were surface coated with poly ethylene glycol (PEG), chitosan (Chit), or alginate (Alg). A solution of cisplatin and a 50:50 blend of polylactic acid (PLA)-polycaprolactone (PCL) dissolved in acetone-dichloromethane mixture was poured into an aqueous solution of PEG (or polyvinyl alcohol or Chit or Alg) with stirring using a high speed homogenizer, for the formation of microspheres. Cisplatin recovery in microspheres ranged from 25-45% depending on the emulsification system used for the preparations. Scanning electron microscopy revealed that the PLA-PCL microspheres were spherical in shape and had a smooth surface texture. The amount of drug release was much higher initially (20-30%), this was followed by a constant slow-release profile for a 30-day period of study. It has been found that drug release depends on the amount of entrapped drug, on the presence of extra cisplatin in the dispensing phase, and on the polymer coatings. This PEG or Alg-coated PLA/PCL microsphere formulation may have potential for the targeted delivery of antiproliferative agents to treat restenosis.     

Biodegradable honeycomb-patterned film composed of poly(lactic acid) and dioleoylphosphatidylethanolamine

Honeycomb-patterned films have been reported to be useful for scaffolds of cell culture in tissue engineering. In the present study, we investigated a new compound, dioleoylphosphatidylethanolamine (DOPE), a naturally derived phospholipid having unsaturated fatty acid moieties, as a surfactant for fabricating honeycomb-patterned poly(d,l-lactide) (PLA) film. Only DOPE among commercially available phospholipids was useful as a surfactant, and it showed good solubility in PLA/chloroform solution and an excellent property for fabricating honeycomb-patterned film (the concentration of DOPE was from 0.2% to 20% by weight based on the weight of PLA). The pore size of the honeycomb was uniform, and all pores were interconnected with each other. The contact angle of water on the honeycomb-patterned film was affected by the amount of DOPE. Time-of-flight secondary ion mass spectrometer (TOF-SIMS) data suggested that DOPE was concentrated on the surface of the honeycomb-patterned film. To investigate cell proliferation and adhesion on the honeycomb-patterned film, NIH3T3 fibroblast cells were cultured on the film. The NIH3T3 cells adhered well on the honeycomb-patterned PLA film with DOPE (PLA-DOPE) and showed good cell proliferation compared to that on honeycomb-patterned PLA film fabricated with a copolymer (CAP) of dodecylacrylamide and omega-carboxyhexylacrylamide (PLA-CAP). These results suggest that the honeycomb-patterned PLA-DOPE can be applicable as a scaffold for cells with better profiles in comparison with PLA-CAP.     

Biodegradable dextran-based microspheres for delivery of anticancer drug mitomycin C

The purpose of this work was to develop a biodegradable microsphere (MS) system for delivering mitomycin C (MMC). Various dextran-based MS systems were investigated for their loading and release characteristics, including nonionic MS, sulfopropyl dextran microspheres (SP-MS) with low or high cross-linking density, oxidized SP-MS (Ox-MS), and hydrophobically modified SP-MS. SP-MS were chemically modified by oxidation with sodium periodate or by reaction with anhydride. The chemical structure of modified SP-MS and MMC-loaded MS (MMC-MS) were examined using Fourier transform infrared (FTIR) and solid-state nuclear magnetic resonance (NMR) spectrophotometry. Drug release was conducted at 37 degrees C in aqueous solutions of 0.15 m phosphate buffer solution. The kinetics of drug absorption and release and the stability of MMC after loading and release were determined by spectrophotometry and high-performance liquid chromatography. Ionic SP-MS exhibited a higher drug-loading rate and capacity when compared to nonionic MS, while hydrophobically modified SP-MS showed an even greater loading capacity than SP-MS. These results suggest that both ionic complexation and hydrophobic interaction were important factors in MMC loading. The Ox-MS system demonstrated higher drug-loading capacity, more fractional drug release and a longer time to reach release equilibrium as compared to other investigated MS systems. Under optimized reaction and loading conditions, MMC released from Ox-MS was found to be unaltered. This work demonstrates that the Ox-MS system is a potentially useful system for the delivery of MMC.     

Arg-Gly-Asp (RGD) peptide conjugated poly(lactic acid)-poly(ethylene oxide) micelle for targeted drug delivery

In this study, a new poly(lactic acid)-poly (ethylene oxide)-Arg-Gly-Asp (PLA-PEO-RGD) derivative was synthesized, and paclitaxel-loaded PLA-PEO-RGD micelles were prepared by this derivative. The solubility assay showed that micelles mixed with Pluronic F-68 as surfactant could increase the solubility of this hydrophobic paclitaxel in aqueous solution. The cell-binding assay showed that PLA-PEO-RGD micelle (IC(50) = 11.13 +/- 1.38 nmol/L) had about 3.6-fold higher integrin avidity than PLA-PEO-RGD conjugates (IC(50) = 40.33 +/- 3.12 nmol/L). The avidity of micelle was also higher than RGD4C peptide (IC(50) = 24.44 +/- 1.21 nmol/L). The in vitro drug release profile of drug-loaded PLA-PEO-RGD micelles exhibited initial burst release to 37% +/- 2% (w/w) during the first 12 h, and then the release rate became steady in a controlled release manner. Furthermore, treatment of the MDA-MB-435 breast cancer cell line with paclitaxel-loaded PLA-PEO-RGD micelles yielded cytotoxicities, with EC(50) values of approximately 30 mumol/L. The paclitaxel-loaded PLA-PEO-RGD micelles treated group showed the most dramatic tumor reduction in MDA-MB-435 tumor-bearing nude mice, and the final mean tumor load was 31 +/- 16 mm(3) (mean +/- SD; n = 8). (125)I-labeled micelles administration resulted in significant (p < 0.001) higher tumor uptake (2.68% +/- 0.14%, ID/g) of PLA-PEO-RGD micelles compared to PLA-PEO micelles (0.84% +/- 0.09%, ID/g) after 2.5 h postinjection. Biodistribution study showed the best blood clearance of PLA-PEO-RGD micelles after 4.5 h postinjection. The results of this study suggest that paclitaxel-loaded PLA-PEO-RGD micelles based on the specific recognition of alpha(V)beta(3) integrin represent a potential and powerful target delivery technology.     

Biodegradable microspheres of novel segmented poly(ether-ester-amide)s based on poly(epsilon-caprolactone) for the delivery of bioactive compounds

A novel class of multiblock poly(epsilon-caprolactone)-based polymers containing hydrophilic trioxyethylene segments and potentially relevant to the delivery of drugs is described in this work. L-phenylalanine residues may also be inserted into the hydrophilic blocks to generate peptide bonds susceptible to enzymatic attack. The investigated polymers were poly(ether-ester-amide)s (PEEAs) obtained by a two-step polymerization procedure from OH-end capped low molecular weight poly(epsilon-caprolactone), sebacoyl chloride and either 4,7,10-trioxa-1,13-tridecanediamine (PEEA1) or 1,13-di(L-phenylalaninamido)-4,7,10-trioxatridecane (PEEA2). PEEAs were characterized by 1H-NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography and were tested for their suitability in producing microspheres. Particles obtained by the single emulsion-solvent evaporation technique were regular and smooth (SEM analysis) showing a monomodal distribution of dimensions. To assess the potentiality of PEEAs in the oral delivery of drugs, three model compounds with different pKa and solubilities--diclofenac, nicardipine and dicumarol--were encapsulated within PEEA microspheres. For the sake of comparison, microspheres prepared from poly(epsilon-caprolactone) (PCL) with a molecular weight similar to PEEAs were also prepared and tested. The release of diclofenac from all the microspheres was very rapid (100% released within 2 h) whereas nicardipine release was slower and biphasic. The initial phase approximated a near zero-order release, being the fraction of nicardipine released after 8 h from PEEA microspheres higher with respect to PCL particles (about 70 vs. 30%). This result was ascribed to the lower crystallinity of PEEAs with respect to PCL which results in a facilitated access of water molecules through the polymer matrix. The lipophilic-unionizable dicumarol was released from PEEA microspheres at a very slow rate. Therefore, dicumarol-loaded PEEA2 microspheres allowed the study of the influence on the release rate of the insertion into the polymer chain of enzymatically degradable bonds. PEEA2 microspheres released dicumarol at the same rate in a medium with or without the proteolitic enzyme alpha-chymotrypsin. Although the insertion of an isolated amino acid was not sufficient to confer enzyme susceptibility to the polymer, the distinctive properties of PEEAs make their use very attractive in the field of controlled release.     

Biodegradable poly(dl-lactic acid) formulations in a calcitonin delivery system

A synthetic analogue of eel calcitonin, [Asu^1,7]-ECT, was incorporated into biodegradable poly(dl-lactic acids) with number-average molecular weights (M_n) of 1400–4400 by the meltpressing technique. The in vitro release of drug from a parabolically degradable poly(DL-lactic acid) with M_n = 1400 showed an initial burst release and completed the release in 3 d from the start of the test. The drug release from a M_n = 4400 polymer with an S-type degradation pattern was kept at 14 ± 5 units/d for an experimental period of 24 d.     

Biodegradable polymeric microspheres and nanospheres for drug delivery in the peritoneum

Drug delivery to the peritoneum is hampered by rapid clearance, and could be improved by application of controlled release technology. We investigated the suitability for peritoneal use of micro- and nanoparticles of poly(lactic-co-glycolic) acid (PLGA), a biodegradable polymer with generally excellent biocompatibility commonly used for controlled drug release. We injected 90 kDa PLGA microparticles, 5-250 microm in diameter, into the murine peritoneum, in dosages of 10-100 mg (n=3-5 per group). We found a high incidence of polymeric residue and adhesions 2 weeks after injection (e.g., 50 mg of 5-microm microparticles caused adhesions in 83% of animals). Histology revealed chronic inflammation, with foreign body giant cells prominent with particles>5 microm in diameter. Five micrometer microspheres made from 54, 57, and 10 kDa PLGA (gamma irradiated) caused fewer adhesions (16.7%) with a similar incidence of residue. Nanoparticles (265 nm) of 90 kDa PLGA also caused much fewer adhesions (6.3% of animals), possibly because they were cleared from the peritoneum within 2 days, and sequestered in the spleen and liver, where foamy macrophages were noted. The effect of sterilization technique on the incidence of adhesion formation is also studied.     

Preparation and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) microspheres for controlled release of paclitaxel

Microspheres of a new kind of copolymer, poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA), are proposed in the present work for clinical administration of an antineoplastic drug paclitaxel with hypothesis that incorporation of a hydrophilic PEG segment within the hydrophobic PLA might facilitate the paclitaxel release. Paclitaxel-loaded PLA-PEG-PLA microspheres of various compositions were prepared by the solvent extraction/evaporation method. Characterization of the microspheres was then followed to examine the particle size and size distribution, the drug encapsulation efficiency, the colloidal stability, the surface chemistry, the surface and internal morphology, the drug physical state and its in vitro release behavior. The effects of polymer types, solvents and drug loading were investigated. It was found that in the microspheres the PEG segment was homogeneously distributed and caused porosity. Significantly faster release from PLA-PEG-PLA microspheres resulted in comparison with the PLGA counterpart. Incorporation of water-soluble solvent acetone in the organic solvent phase further increased the porosity of the PLA-PEG-PLA microspheres and facilitated the drug release. A total of 49.6% sustained release of paclitaxel within 1 month was achieved. Potentially, the presence of PEG on the surface of PLA-PEG-PLA microspheres could improve their biocompatibility. PLA-PEG-PLA microspheres could thus be promising for the clinical administration of highly hydrophobic antineoplastic drugs such as paclitaxel.     

Immune responses in mice of beta-galactosidase adsorbed or encapsulated in poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres

The immune response induced in mice by beta-galactosidase (beta-gal) adsorbed or encapsulated on poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) microspheres was investigated. The encapsulated protein elicited higher antibody response than the protein adsorbed on the microspheres in the case of the PLA microspheres. However, the encapsulated protein elicited weaker antibody response than the adsorbed protein in the case of the PLGA (50:50) microspheres, probably because, in this case, the encapsulation process adversely affected protein immunogenicity. In the case of adsorbed beta-gal, higher antibody response was obtained with the PLA microspheres than with the PLGA (50:50) microspheres. This may be related to the lower rate of beta-gal desorption from the PLA microspheres. Based on the immunoglobulin G1/immunoglobulin G2a ratios and the stimulation indices for interferon-gamma and interleukin-4, beta-gal encapsulated or adsorbed on PLA microspheres induced a Th(1)-biased immune response whereas beta-gal encapsulated or adsorbed on PLGA (50:50) microspheres induced a Th(2)-biased immune response. The results obtained indicate that more potent immune responses are obtained when the protein is encapsulated than adsorbed on the microspheres, providing that the encapsulation process does not adversely affect protein immunogenicity. Also, the type of polymer used to prepare the microspheres, but not the method of protein association with the microspheres, may affect the type of immune response.     

Biodegradable thermogelling poly(ester urethane)s consisting of poly(lactic acid)--thermodynamics of micellization and hydrolytic degradation

Multiblock poly(ether ester urethane)s comprising of poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized, and their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 7 to 9 wt%. The chemical structures and molecular characteristics of the copolymers were studied by GPC, 1H NMR, 13C NMR and FTIR. The thermal stability of the poly(PEG/PPG/PLA urethane)s was studied by thermogravimetry analysis (TGA), and the PLA contents were calculated based on the thermal degradation profile. The results were in good agreement with those obtained from the 1H NMR measurements. The critical micellization concentration (CMC) of these water-soluble poly(ether ester urethane)s was determined at different temperatures using a dye solubilization method. The thermodynamic parameters for micelle formation were calculated, indicating that the process is largely entropy-driven. Interestingly, it appears that there exists a requirement for the system to possess a minimum gain in entropy before the thermogelling effect can be observed. Dilute copolymer solutions showed a lower critical solution temperature (LCST) behavior similar to pNIPAM dissolved in aqueous solutions. The thermogels hydrolytically degraded to polymer fragments corresponding to the constituent segment blocks within 3 months.     

Covalent attachment of Mn-porphyrin onto doxorubicin-loaded poly(lactic acid) nanoparticles for potential magnetic resonance imaging and pH-sensitive drug delivery

In this paper, theranostic nanoparticles (MnP-DOX NPs) were fabricated by conjugating Mn-porphyrin onto the surface of doxorubicin (DOX)-loaded poly(lactic acid) (PLA) nanoparticles (DOX NPs) for potential T₁ magnetic resonance imaging and pH-sensitive drug delivery. An in vitro drug release study showed that the release rate of DOX from MnP-DOX NPs was slow at neutral pH but accelerated significantly in acidic conditions. It was found that MnP-DOX NPs could be easily internalized by HeLa cells and effectively suppressed the growth of HeLa cells and HT-29 cells due to the accelerated drug release in acidic lysosomal compartments. Magnetic resonance imaging (MRI) scanning analysis demonstrated that MnP-DOX NPs had much higher longitudinal relaxivity in water (r₁ value of 27.8 mM^?1 s^?1 of Mn³⁺) than Mn-porphyrin (Mn(III)TPPS3NH₂; r₁ value of 6.70 mM^?1 s^?1 of Mn³⁺), behaving as an excellent contrast agent for T₁-weighted MRI both in vitro and in vivo. In summary, such a smart and promising nanoplatform integrates multiple capabilities for effective cancer diagnosis and therapy.     

乳酸-羟基乙酸共聚物多肽蛋白类药物微球控释系统的突释与控制

背景：突释问题是限制多肽蛋白类微球广泛应用的一个关键技术问题,已经成为PLGA微球控释系统面临的一个亟待解决的问题。 目的：分析近年来国内外对乳酸-羟基乙酸共聚物多肽蛋白类药物微球的突释与控制的研究,对突释的原因、影响突释的因素以及减少突释的方法与措施进行了详细的介绍。 方法：应用计算机检索CNKI和PubMed数据库中1999-01/2010-12关于乳酸-羟基乙酸共聚物多肽蛋白类药物微球控释系统研究的文章,在标题和摘要中以“聚乳酸-羟基乙酸;多肽;蛋白;微球;突释;控制”或“PLGA; peptide; protein ; microspheres; burst release; control”为检索词进行检索。通过阅读标题和摘要进行初选,排出较陈旧和重复研究文献,保留符合纳入标准的文献24篇。 结果与结论：对乳酸-羟基乙酸共聚物多肽蛋白类药物微球突释机制的理解,可以更好地实现对微球突释的控制,以扩大多肽蛋白类药物在临床上的应用。PLGA的性质、微球的制备方法、微球的制备参数都在不同程度上影响微球的突释,并且可能是多因素协同作用。通过对上述各种因素加以适当控制,可在一定程度上减少微球的突释率。通过该方面的机制研究对指导新药开发具有重要意义。     

Enhancement of poly(orthoester) microspheres for DNA vaccine delivery by blending with poly(ethylenimine)

Poly(orthoester) (POE) microspheres have been previously shown to possess certain advantages for the in vivo delivery of DNA vaccines. In particular, timing of DNA release from POE microspheres in response to acidic phagosomal pH was shown to be an important factor in determining immunogenicity, which was hypothesized to be linked to the natural progression of antigen-presenting cell uptake, transfection, maturation, and antigen presentation. Here we report in vitro characterization of the enhanced efficacy of POE microspheres by blending poly(ethylenimine) (PEI), a well-characterized cationic transfection agent, into the POE matrix. Blending of a tiny amount of PEI (approximately 0.04 wt%) with POE caused large alterations in POE microsphere properties. PEI provided greater control over the rate of pH-triggered DNA release by doubling the total release time of plasmid DNA and enhanced gene transfection efficiency of the microspheres up to 50-fold without any significant cytotoxicity. Confocal microscopy results of labeled PEI and DNA plasmids revealed that PEI caused a surface-localizing distribution of DNA and PEI within the POE microsphere as well as focal co-localization of PEI with DNA. We provide evidence that upon degradation, the microspheres of POE-PEI blends released electrostatic complexes of DNA and PEI, which are responsible for the enhanced gene transfection. Furthermore, blending PEI into the POE microsphere induced 50-60% greater phenotypic maturation and activation of bone marrow-derived dendritic cells in vitro, judged by the up-regulation of co-stimulatory markers on the cell surface. Physically blending PEI with POE is a simple approach for modulating the properties of biodegradable microspheres in terms of gene transfection efficiency and DNA release kinetics. Combined with the ability to induce maturation of antigen-presenting cells, POE-PEI blended microspheres may be excellent carriers for DNA vaccines.     

Biodegradable microspheres as a vaccine delivery system

The utility of biodegradable and biocompatible microspheres as a vaccine delivery system for the induction of systemic and disseminated mucosal antibody responses was investigated. Intraperitoneal (ip) injection into mice of 1-10 microns microspheres, constructed of the copolymer poly(DL-lactide-coglycolide) (DL-PLG) which contained approximately 1% by weight a formalinized toxoid vaccine of staphylococcal enterotoxin B (SEB), dramatically potentiated the circulating IgG anti-toxin antibody response as compared to the free toxoid. The initiation of vaccine release was delayed in larger microspheres, and a mixture of 1-10 and 20-50 microns microspheres stimulated both a primary and an anamnestic secondary anti-toxin response following a single injection. However, neither free nor microencapsulated SEB toxoid induced a detectable mucosal IgA anti-toxin response following systemic injection. In contrast, three peroral immunizations with toxoid-microspheres stimulated circulating IgM, IgG and IgA anti-toxin antibodies and a concurrent mucosal IgA response in saliva, gut washings and lung washings. Systemic immunization with microencapsulated toxoid primed for the induction of disseminated mucosal IgA responses by subsequent oral or intratracheal (it) boosting in microspheres, while soluble toxoid was ineffective at boosting. These results indicate that biodegradable and biocompatible microspheres represent an adjuvant system with potentially widespread application in the induction of both circulating and mucosal immunity.     

Paclitaxel and etoposide-loaded Poly (lactic-co-glycolic acid) microspheres fabricated by coaxial electrospraying for dual drug delivery

Abstract

In this study, we fabricated paclitaxel (PTX) and etoposide (ETP) loaded Poly (lactic-co-glycolic acid) (PLGA) microspheres with core–shell structures and particle sizes ranging from 1 to 4?µm by coaxial electrospraying. The microspheres were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM). The drug loading rate and entrapment efficiency of the microspheres were detected by high performance liquid chromatograph (HPLC). Moreover, the drug release profiles and degradation of drug-loaded PLGA microspheres in vitro were investigated, respectively. The distinct layered structure that existed in the manufactured core–shell microspheres can be observed by TEM. The in vitro release profiles indicated that the PLGA/PTX?+?ETP (PLGA/PE) microspheres exhibited the controlled release of two drugs in a sequential manner. Cell Counting Kit-8 was used to detect the toxic and side effects of the microspheres on bone tumor cells. PTX and ETP for combination drug therapy loaded microspheres had more cytotoxic effect on saos-2 osteosarcoma cells than the individual drugs. In conclusion, core–shell PLGA microspheres by electrospraying for combination drug therapy is promising for medicine applications, the PLGA/PE microspheres have some potential for osteosarcoma treatment.     

Cytoplasmic delivery of a macromolecular fluorescent probe by poly(d, l-lactic-co-glycolic acid) microspheres

A macromolecular fluorescent probe encapsulated in poly(d, l-lactic-co-glycolic acid) (PLGA) microspheres was used as a model for studying cytoplasmic delivery of antigens. We hypothesized that Texas red dextran loaded in PLGA microspheres would be delivered to the cytoplasm and that cytoplasmic delivery would be affected by polymer molecular weight. Cellular localization of the Texas red dextran was investigated at two different molecular weights of PLGA: 6000 and 60,000 g/mol. Intracellular degradation and processing of Texas red dextran-loaded PLGA microspheres by mouse peritoneal macrophages was monitored both in vitro and in vivo for a 7-day period using confocal laser scanning microscopy (CLSM). The results revealed cytoplasmic delivery of the fluorescent probe at both molecular weights of PLGA. Furthermore, the CLSM images showed that both in vitro and in vivo, the kinetics of microsphere degradation and cytoplasmic delivery were more rapid for the 6000 g/mol PLGA microspheres than the 60,000 g/mol PLGA microspheres. Hence, this study provides physical evidence that PLGA microspheres are capable of cytoplasmic delivery and that delivery to the cytosol can be controlled by modifying formulation parameters such as polymer molecular weight.     

Biodegradable arginine-based poly(ester-amide)s as non-viral gene delivery reagents

A novel family of synthetic biodegradable poly(ester-amide)s (Arg-PEAs) was evaluated for their biosafety and capability to transfect rat vascular smooth muscle cells, a major cell type participating in vascular diseases. Arg-PEAs showed high binding capacity toward plasmid DNA, and the binding activity was inversely correlated to the number of methylene groups in the diol segment of Arg-PEAs. All Arg-PEAs transfected smooth muscle cells with an efficiency that was comparable to the commercial transfection reagent Superfect. However, unlike Superfect, Arg-PEAs, over a wide range of dosages, had minimal adverse effects on cell morphology, viability or apoptosis. Using rhodamine-labeled plasmid DNA, we demonstrated that Arg-PEAs were able to deliver DNA into nearly 100% of cells under optimal polymer-to-DNA weight ratios, and that such a high level of delivery was achieved through an active endocytosis mechanism. A large portion of DNA delivered, however, was trapped in acidic endocytotic compartments, and subsequently was not expressed. These results suggest that with further modification to enhance their endosome escape, Arg-PEAs can be attractive candidates for non-viral gene carriers owning to their high cellular uptake nature and reliable cellular biocompatibility.