Liposome-Mediated Delivery of Gallium to Macrophage-Like Cells in Vitro: Demonstration of a Transferrin-Independent Route for Intracellular Delivery of Metal Ions

Gallium (Ga) prevents the activation of macrophages and might be useful as an immunosuppressive agent. It is taken up by the malignant cells through the transferrin (Tf) receptor pathway, but this pathway may be insufficient in the case of non-malignant cells. We studied the Tf-independent, liposome-mediated delivery of Ga to macrophage-like cells in vitro by a growth inhibition assay. The growth inhibitory properties of Ga for other types of cells was also evaluated. Ga complexed with nitrilotriacetate (GaNTA) and encapsulated in DSPG-liposomes was 16 and 48 times more potent for RAW 264 cells than free GaNTA and Ga-nitrate, respectively. CV1-P cells were also somewhat sensitive to liposomal Ga, but other cell lines with lower endocytotic capacity were insensitive. The inhibition of RAW 264 cell growth induced by liposomal or free GaNTA was partially reversed with iron-loading of the cells, indicating that this form of Ga causes an intracellular iron deficiency similar to that produced by Tf-bound Ga. Our results indicate that encapsulation of Ga in negatively charged liposomes provides a transferrin independent route for intracellular delivery of the compound to macrophages, which is of special interest in the treatment of autoimmune diseases, such as rheumatoid arthritis.     

基于pH梯度载药技术的咪喹莫特脂质体的制备工艺研究

目的 根据咪喹莫特的理化性质,利用pH梯度主动载药技术制备脂质体,考察其性状、粒径、表面电荷及体外释药特征。方法 葡聚糖凝胶滤过法测定脂质体的包封率,以包封率与成型性为主要指标筛选制备方法,考察水化液的种类、pH值、离子强度及pH梯度载药、磷脂-胆固醇比例、脂药比、维生素E用量对包封率的影响;正交试验优化咪喹莫特脂质体的处方,考察脂质体样品在0~4℃下的稳定性。结果 按处方咪喹莫特50 mg、大豆卵磷脂400 mg、胆固醇130 mg、油酸10 mg、维生素E 5 mg、柠檬酸pH 2.5缓冲液5 mL,采用薄膜分散法工艺制备脂质体样品,并进行pH梯度主动载药,pH值调至7.0。制得的咪喹莫特脂质体呈白色均匀的混悬液,脂质体微粒圆整,分散性好,粒径（347±21）nm,包封率（81.2±1.9）%,Zeta电位（-12.19±1.7）mV。结论 pH梯度主动载药技术适于咪喹莫特脂质体的制备。     

壳聚糖包覆脂质体递药系统的研究进展

脂质体在药物传递方面被广泛研究,但因结构稳定性差等因素使其应用受到了限制.壳聚糖是一种阳离子多糖,具有良好的生物相容性、生物降解性以及生物黏附性,并且可经化学改性成为性能更佳的壳聚糖衍生物.近年来,壳聚糖及其衍生物包覆脂质体在载药方面的研究得到了越来越多学者的关注.壳聚糖或其衍生物修饰脂质体,可提高其稳定性、黏附渗透性...     

土贝母皂苷甲长循环脂质体的制备及体外性质考察

目的 制备土贝母皂苷甲长循环脂质体（tubeimoside A long-circulating liposomes,TA-LC-Lipo）,并进行体外性质考察。方法 乙醇注入法制备TA-LC-Lipo;采用HPLC测定包封率及体外释放率;通过Marlvern激光粒径分析仪测定粒径和Zeta电位;肉眼观察法和紫外分光光度法评价其溶血作用。结果 确定处方为大豆磷脂浓度10 mg·mL^-1、药脂比1：10、大豆磷脂：胆固醇=4：1、DSPE-PEG 2000的摩尔含量为5%。制备得到的TA-LC-Lipo的平均粒径、PDI、电位、包封率分别为123.0 nm,0.134,-1.20 mV,86.2%。结论 制得的TA-LC-Lipo粒度分布均匀,包封率较高,有较好的缓释作用,并能有效改善土贝母皂苷甲的溶血现象。     

In Vitro Evaluation of Polymerized Liposomes as an Oral Drug Delivery System

The physical characteristics of polymerized liposomes for potential use as an oral drug delivery system were examined in vitro. The trap efficiency in monomeric liposomes composed of 1,2-di (2,4-octadecadienoyl) phosphatidylcholine was increased from 3% for original multilamellar vesicles to 35% for freeze-thaw treated liposomes. Polymerized liposomes with azobis (isobutyronitrile) and azobis (2-amidinopropane) hydrochloride as radical initiators showed complete stability against solubilization by Triton X-100, a detergent chosen to mimic bile salts. Release rates of ¹⁴C-BSA and ¹⁴C-sucrose in media simulating the gastro-intestinal fluids was 50% less than from regular liposomes composed of hydrogenated egg phosphatidylcholine mixed with cholesterol (molar ratio 1:1), which can be regarded as one of the most stable types of regular liposomes. It was estimated that, when administered orally, polymerized liposomes can reach the intestine while maintaining their vesicle structure and keeping at least 75% of their original content.     

In Vivo Gene Delivery to the Liver Using Novel Galactosylated Cationic Liposomes

Purpose. The purpose of this study is to elucidate the in vivo genetransfer for galactosylated liposomes containingcholesten-5-yloxy-N-(4-((1-imino-2--D-thiogalactosylethyl)amino)butyl)formamide(Gal-C4-Chol)in relation to lipid composition and charge ratio. Methods. Galactosylated cationic liposomes containingN-]1-(2,3-dioleyloxy)propyl]-n,n,n-trimethylammonium chloride(DOTMA),Gal-C4-Chol and cholesterol(Chol), and similar liposomes were prepared.Plasmid DNA complexed with a galactosylated liposome preparationwas injected intraportally into mice. The mice were sacrificed after 6hours. The tissues were subjected to luciferase assay. Results. A markedly higher gene expression in the liver followinginjection of plasmid DNA that has been complexed withDOTMA/Chol/Gal-C4-Chol(1:0.5:0.5) and DOTMA/Gal-C4-Chol(1:1)liposomes was observed. The effect was one order of magnitude higherthan naked DNA and DOTMA/Chol(1:1) liposomes. Pre-exposing withgalactosylated bovine serum albumin significantly reduced the hepaticgene expression. By comparison, the gene expression for galactosylatedcationic liposomes containing3[N-(N,N-dimethylaminoethane)-carbamoyl]cholesterol,Gal-C4-Chol and dioleoylphosphatidylethanolamine was 10 times lower.As far as the charge ratio of DOTMA/Chol/Gal-CA-Chol(1:0.5:0.5) liposomesto plasmid DNA(1.6-7.0) was concerned, complexes with charge ratiosof 2.3-3.1 produced maximal gene expression in the liver. Whereas,higher ratios resulted in enhanced expression in the lung. Conclusions. By optimizing lipid composition and charge ratio,galactosylated liposome/DNA complexes allow superior in vivo genetransfection in the liver via asialoglycoprotein receptor-mediatedendocytosis.     

Structural Requirements for Cationic Lipid Mediated Phosphorothioate Oligonucleotides Delivery to Cells in Culture

Abstract

A series of 2,3-dialkyloxypropyl quaternary ammonium lipids containing hydroxyalkyl chains on the quaternary amine were synthesized, formulated with dioleoylphosphatidylethanolamine (DOPE) and assayed for their ability to enhance the activity of an intercellular adhesion molecule 1 (ICAM-1) antisense oligonucleotide, ISIS 1570. Cationic liposomes prepared with hydroxyethyl, hydroxypropyl and hydroxybutyl substituted cationic lipid all enhanced the activity of the ICAM-1 antisense oligonucleotide. Cationic lipids containing hydroxypentyl quaternary amines only marginally enhanced the activity of ISIS 1570. Hydroxyethyl cationic lipids synthesized with dimyristyl (C_14:0) and dioleyl (C_18:1) alkyl chains were equally effective. Activity of cationic lipids containing saturated alkyl groups decreased as the chain length increased, i.e. the dimyristyl (C_14:0) was more effective than dipalmityl (C_16:0) lipid, which was more effective than distearyl (C_18:0). The phase transition temperature of cationic lipids containing saturated aliphatic chains was 56°C for the distearyl lipid, 42°C for the dipalmityl lipid and 24°C for the dimyristyl lipid. Cationic lipids with dioleyl alkyl chains required DOPE for activity, with optimal activity occurring at 50 mole%. In contrast, a dimyristyl containing cationic lipid did not require DOPE to enhance the activity of ISIS 1570. Formulation with different phosphatidylethanolamine derivatives, revealed that optimal activity was obtained with DOPE. These studies demonstrate that several cationic lipid species enhance the activity of phosphorothioate antisense oligonucleotides and provide further information on the mechanism by which cationic lipids enhance the activity of phosphorothioate oligodeoxynucleotides.     

Site-Specific Drug Delivery to Pilosebaceous Structures Using Polymeric Microspheres

In order to improve the therapeutic index of adapalene, a new drug under development for the treatment of acne, site-specific delivery to the hair follicles using 50:50 poly(DL-lactic-co-glycolic acid) microspheres as particulate carriers was investigated in vitro and in vivo. The percutaneous penetration pathway of the microspheres was shown to be dependent on their mean diameter. Thus, after topical application onto hairless rat or human skin, adapalene-loaded microspheres (5-µm diameter) were specifically targeted to the follicular ducts and did not penetrate via the stratum corneum. The in vitro release of adapalene from the microspheres into artificial sebum at 37°C was controlled and faster than the in vivo sebum excretion in humans. Aiming to reduce either the applied dose of drug or the frequency of administration, different formulations of adapalene-loaded microspheres were evaluated in vivo in the rhino mouse model. A dose-related comedolytic activity of topical formulations of adapalene-loaded microspheres was observed in this model. Furthermore, by applying a site-specific drug delivery system (0.1% adapalene) every other day or by administering a 10-fold less concentrated targeted formulation (0.01%) every day, a pharmacological activity equivalent to a daily application of an aqueous gel containing drug crystals (0.1% adapalene) was observed. Since an aqueous gel containing 10% adapalene-loaded microspheres was not irritating in a rabbit skin irritancy test, this formulation was applied onto forearms of human volunteers. Site-specific drug delivery was further evidenced by follicular biopsy. These results support the view that follicular drug targeting using 5-µm polymeric microspheres may represent a promising therapeutic approach for the treatment of pathologies associated with pilosebaceous units.     

胰岛素脂质体的制备及在电致孔下的经皮渗透

采用反相蒸发法制备了平均粒径122.7nm的胰岛素脂质体,并考察了电致孔经皮转运情况.结果表明,在电致孔条件下,胰岛素脂质体2h累积渗透量是载药脂质体被动扩散的1倍;是原药及其与空白脂质体混合物的2～3倍.     

Delivery of Plasmid DNA into Mammalian Cell Lines Using pH-Sensitive Liposomes: Comparison with Cationic Liposomes

We compare the transfection efficiency of plasmid DNA encoding either luciferase or (-galactosidase encapsulated in pH-sensitive liposomes or non-pH-sensitive liposomes or DNA complexed with cationic liposomes composed of dioleoyloxypropyl-trimethylammonium:dioleoylphosphatidyl-ethanolamine (1:1, w/w) (Lipofectin) and delivered into various mammalian cell lines. Cationic liposomes mediate the highest transient transfection level in all cell-lines examined. pH-sensitive liposomes, composed of cholestryl hemisuccinate and dioleoylphosphatidylethanolamine at a 2:1 molar ratio, mediate gene transfer with efficiencies that are 1 to 30% of that obtained with cationic liposomes, while non-pH-sensitive liposome compositions do not induce any detectable transfection. Cationic liposomes mediate a more rapid uptake of plasmid DNA, to about an eightfold greater level than that obtained with pH-sensitive liposomes. The higher uptake of DNA mediated by Lipofectin accounts for part of its high transfection efficiency. Treatment of cells with chloroquine, ammonium chloride, or monensin decreases (threefold) transfection using pH-sensitive liposomes and either has no effect on or enhances cationic liposome-mediated transfection. Therefore plasma membrane fusion is not the only mechanism available to cationic liposomes; in certain cell lines DNA delivery via endocytosis is a possible parallel pathway and could augment the superior transfection efficiency observed with cationic liposomes.     

Liposomes Dispersed Within a Thermosensitive Gel: A New Dosage Form for Ocular Delivery of Oligonucleotides

Purpose. The main goal of this study was to develop an ocular controlled release formulation of a model oligonucleotide (pdT16), contained within liposomes dispersed within a thermosensitive gel composed by poloxamer 407. Methods. The influence of the poloxamer concentration 2% or 27% on the stability of the liposomes (PC: CHOL and PC: CHOL: PEG-DSPE) was investigated. The in vitro release profiles of pdT16 from various poloxamer formulations (free pdT16 dispersed within 20% and 27% poloxamer gels, pdT16 encapsulated within liposomes dispersed within 20% and 27% poloxamer gels) were realized using a membrane-free release model. Results. The dispersion of liposomes within a dilute 2% poloxamer solution resulted in a great leakage of pdT16 from liposomes. However, the destabilization effect of poloxamer was reduced when higher concentration (27%) was used. Poloxamer dissolution was found to control the release process of pdT16, whereas the dispersion of liposomes within 27% poloxamer gel was shown to slow down the diffusion of pdT16 out from the gel. Conclusions. The dispersion of liposomes within a 27% poloxamer gel presented an interesting system to control the release of a model oligonucleotide compare to a simple gel.     

pH敏感型纳米递药系统在肿瘤靶向治疗中的作用

目的 综述目前pH敏感纳米递药系统用于肿瘤靶向治疗中的国内外研究进展。方法 在Pubmed和Google上检索近年国内外资料,阐明pH敏感纳米递药系统靶向肿瘤治疗的作用机制,对超顺磁性纳米粒、胶束、树状大分子等相关研究成果进行总结和评价。结果 传统肿瘤化疗药物普遍存在疗效低、副作用大等问题,而近年来研发的pH响应的纳米载体可通过EPR效应积聚于肿瘤组织,并在弱酸性的肿瘤细胞外液或经内吞作用后在细胞质或溶酶体中释放药物。该pH敏感型载体能促进药物的靶向递送,在减少系统性副作用的同时提高肿瘤化疗疗效。结论 pH敏感纳米递药系统在肿瘤靶向治疗中具有广阔的应用前景,开发具有靶向性、高效性、安全性的递药系统是目前该领域研究主要方向之一。     

Effective Targeting of Liposomes to Liver and Hepatocytes In Vivo by Incorporation of a Plasmodium Amino Acid Sequence

Purpose Several species of the protozoan Plasmodium effectively target mammalian liver during the initial phase of host invasion. The purpose of this study was to demonstrate that a Plasmodium targeting amino acid sequence can be engineered into therapeutic nanoparticle delivery systems. Methods A 19-amino peptide from the circumsporozoite protein of Plasmodium berghei was prepared containing the conserved region I as well as a consensus heparan sulfate proteoglycan binding sequence. This peptide was attached to the distal end of a lipid–polyethylene glycol bioconjugate. The bioconjugate was incorporated into phosphatidylcholine liposomes containing fluorescently labeled lipids to follow blood clearance and organ distribution in vivo. Results When administered intravenously into mice, the peptide-containing liposomes were rapidly cleared from the circulation and were recovered almost entirely in the liver. Fluorescence and electron microscopy demonstrated that the liposomes were accumulated both by nonparenchymal cells and hepatocytes, with the majority of the liposomal material associated with hepatocytes. Accumulation of liposomes in the liver was several hundredfold higher compared to heart, lung, and kidney, and more than 10-fold higher compared to spleen. In liver slice experiments, liposome binding was specific to sites sensitive to heparinase. Conclusions Incorporation of amino acid sequences that recognize glycosaminoglycans is an effective strategy for the development of targeted drug delivery systems. K. J. Longmuir and R. T. Robertson were the primary investigators for this study.     

新型脂质体在经皮给药系统中的应用

摘 要 药物经皮传递系统的角质层屏障等问题日益受到关注,而新型脂质体作为药物传递载体,可以有效解决这一问题。新型脂质体能明显提高药物经皮渗透,从而增强疗效,具有广阔的应用价值和开发前景。本文结合国内外研究现状,对在经皮给药系统中作为载体应用的新型脂质体的分类、促渗机制及其应用进展做一综述。     

In Vivo ESR Studies on Subcutaneously Injected Multilamellar Liposomes in Living Mice

PURPOSE: An innovative, noninvasive, low-frequency electron spin resonance (ESR) spectroscopy method was applied and adapted to investigate the integrity of multilamellar liposomes from hydrogenated phospholipids after subcutaneous injection in living mice. Moreover, the fate of the injected liposomal preparations was examined, as well as the possibility to achieve a depot effect. METHODS: Highly concentrated solutions of the spin probe 2,2,6,6-tetramethyl-4-trimethylammoniumpiperidine-1-oxyl-iodide (CAT-1; 138 mM) were encapsulated in liposomes. They were characterized by laser diffraction, and the liberation of spin probe was investigated by ESR spectroscopy. RESULTS: Line shape changes allowed the differentiation between encapsulated and released CAT-1 after subcutaneous injection of liposomes. Multilamellar liposomes form a local depot at the site of injection. A sustained release of the spin probe from the depot was monitored by means of ESR. Whereas 40% of the spin probe was released within the first 96 h after administration, 60% remained in intact liposomes under the skin. No depot formation could be observed after injection of CAT-1 solutions, but a fast signal decrease due to systemic distribution and bioreduction of the nitroxide spin probe. CONCLUSIONS: Noninvasive analysis of liposomal integrity in living animals was successfully accomplished using a new L-Band ESR spectroscopy method. The liberation of CAT-1 from liposomes in vitro and in vivo was monitored by changes in the lineshape of ESR spectra and Heisenberg spin exchange. The significance of liposomal integrity for the formation of a localized drug depot effect was proved.     

Transbuccal Delivery of Acyclovir: I. In Vitro Determination of Routes of Buccal Transport

Purpose. To determine the major routes of buccal transport of acyclovir and to examine the effects of pH and permeation enhancer on drug permeation. Methods. Permeation of acyclovir across porcine buccal mucosa was studied by using side-by-side flow through diffusion cells at 37°C. The permeability of acyclovir was determined at pH range of 3.3 to 8.8. Permeability of different ionic species was calculated by fitting the permeation data to a mathematical model. Acyclovir was quantified using HPLC. Results. Higher steady state fluxes were observed at pH 3.3 and 8.8. The partition coefficient (1-octanol/buffer) and the solubility of acyclovir showed the same pH dependent profile as that of drug permeation. In the presence of sodium glycocholate (NaGC) (2–100 mM), the permeability of acyclovir across buccal mucosa was increased 2 to 9 times. This enhancement was independent of pH and reached a plateau above the critical micelle concentration of NaGC. The permeabilities of anionic, cationic, and zwitterionic species were 3.83 × 10^–5, 4.33 × 10^–5, and 6.24 × 10^–6cm/sec, respectively. Conclusions. The in vitropermeability of acyclovir across porcine buccal mucosa and the octanol-water partitioning of the drug were pH dependent. A model of the paracellular permeation of the anionic, cationic, and zwitterionic forms of acyclovir is consistent with these data. The paracellular route was the primary route of buccal transport of acyclovir, and the enhancement of transbuccal transport of acyclovir by sodium glycocholate (NaGC) appeared to operate via this paracellular route.     

Transdermal Delivery of the Synthetic Cannabinoid WIN 55,212-2: In Vitro/in Vivo Correlation

PURPOSE: The aim of the current investigation was to evaluate the percutaneous absorption of the synthetic cannabinoid WIN 55,212-2 in vitro and in vivo. METHODS: The in vitro permeation studies of WIN 55,212-2 in human skin, hairless guinea pig skin, a polymer membrane with adhesive, and a skin/polymer membrane composite were conducted in flowthrough diffusion cells. The pharmacokinetic parameters for WIN 55,212-2 were determined after intravenous administration and topical application of Hill Top Chambers and transdermal therapeutic systems (TTS) in guinea pigs. RESULTS: The in vitro permeation studies indicated that the flux of WIN 55,212-2 through hairless guinea pig skin was 1.2 times more than that through human skin. The flux of WIN 55,212-2 through human and guinea pig skin was not significantly higher than that through the corresponding skin/polymer membrane composites. The mean guinea pig steady-state plasma concentrations after topical 6.3 cm2 chamber and 14.5 cm2 TTS patch applications were 5.0 ng/ml and 8.6 ng/ml, respectively. CONCLUSIONS: The topical drug treatments provided significant steady-state plasma drug levels for 48 h. The observed in vivo results from the Hill Top Chambers and TTS patches in the guinea pigs were in good agreement with the predicted plasma concentrations from the in vitro data.     

Antibody Dependent,Complement Mediated Liver Uptake of Liposomes Containing GM1

Purpose. We have previously reported that GM_l exhibits an opposite effect on regulating liposome circulation time in mice and rats (Liu et al. Pharm. Res. Vol. 12:508-512 (1995)). Inclusion of GM₁ into liposomes significantly prolongs liposome circulation time in mice, while it dramatically decreases the blood half life and increases liver uptake of liposomes in rats. The purpose of this study was to elucidate the mechanism that underlies this phenomenon. Methods. Single-pass liver perfusion in vitro and complement mediated liposome lysis assay was used. Results. Serum appeared to play an important role in determining the liver uptake of GM_l liposomes. Specifically, rat serum enhanced the uptake of GM₁ containing liposomes by the perfused liver. Such activity was also found in human and bovine serum, but not in mouse serum. Taking human serum as an example, we demonstrated that such serum activity can be blocked by EDTA and EGTA/Mg^{2 +}. Antibodies against human IgM and the third component of complement system (C3) also inhibited serum activity. Conclusions. The presence of naturally occurring anti-GM₁ antibodies in rats, through the activation of the classic pathway of complement system, is likely the cause of rapid blood clearance of GM₁ liposomes. The third component of complement is likely to serve as the opsonin that is directly involved in mediating liposome clearance.     

Entrapment of Cyclodextrin-Drug Complexes into Liposomes: Potential Advantages in Drug Delivery

Abstract

A novel concept in drug delivery discussed here, takes advantage of certain properties of the drug “containers” cyclodextrins and liposomes to combine them into a single system thus circumventing problems associated with both systems. The concept, entailing entrapment of water-soluble cyclodextrin-drug inclusion complexes in liposomes, would allow accommodation of insoluble drugs in the aqueous phase of vesicles. This would potentially increase the drug to lipid mass ratio to levels above those attained by conventional drug incorporation into the lipid phase, enlarge the range of insoluble drugs amenable to encapsulation to include, for instance, membrane destabilizing agents, allow targeting of complexes to specific sites and reduce toxicity. In the present work, soluble inclusion complexes of hydroxypropyl-β-cyclodextrin with dehydroepiandrosterone, retinol and retinoic acid were prepared and entrapped into mutlilamellar liposomes by the dehydration-rehydration procedure. Complex-containing liposomes were then exposed to blood plasma. Results show that complex entrapment into liposomes depends on the lipid composition used. Nearly all of the cyclodextrin and considerable portions of the drugs were found to remain associated with the carrier in the presence of plasma.     

Culture of Calu-3 Cells at the Air Interface Provides a Representative Model of the Airway Epithelial Barrier

Purpose The aim of this study was to compare the effect of liquid-covered culture (LCC) and air-interfaced culture (AIC) on Calu-3 cell layer morphology and permeability, thus assessing the fitness of these culture systems as models of airway epithelium barrier function. Methods Cell layers were grown on 0.33 cm² Transwell polyester cell culture supports. Cell layers grown using LCC and AIC were evaluated by using light and electron microscopy, transepithelial electrical resistance (TER), and permeability to the transepithelial flux of fluorescein sodium (flu-Na), and by varying molecular weight dextrans labeled with fluorescein isothiocyanate (FITC-dex). The tight junction protein, zona occludens protein-1 (ZO-1), was visualized by confocal microscopy and apical glycoprotein secretions were identified by using alcian blue. Results Cells grown via AIC produced a more columnar epithelium with a more rugged apical topography and greater glycoprotein secretion compared to cells grown via LCC. Apical protrusions appearing to be cilia-like structures were observed on occasional cells using AIC, but typical airway ciliated cell phenotypes were not produced under either condition. Secretory granules were observed in cells cultured under both conditions. Cells cultured using LCC exhibited higher levels of ZO-1 protein than the AIC counterpart. The maximal TER of cells using LCC, 1,086 ± 113 Ω cm² at 11–16 days, was significantly greater than the TER of cells cultured using AIC, 306 ± 53 Ω cm² at 11–13 days. Apparent permeability (P_app) values for the transport of flu-Na using LCC and AIC were 1.48 ± 0.19×10⁻⁷ and 3.36 ± 0.47×10⁻⁷ cm s⁻¹, respectively. Transport rates of flu-Na and FITC-dex were inversely proportional to molecular weight, and were significantly lower (p < 0.05) in cell layers grown using LCC than AIC. Renkin analysis fitted the data to single pore populations of radii 7.7 and 11.0 nm for LCC and AIC, respectively. Conclusion Distinct differences in morphology and permeability result when Calu-3 cells are grown using AIC or LCC. Cells cultured using AIC generate a model more morphologically representative of the airway epithelium than cells cultured using LCC.