Biomaterials (v.30, #19)
Dynamic culture conditions to generate silk-based tissue-engineered vascular grafts
by Xiaohui Zhang; Xiuli Wang; Vinny Keshav; Xiaoqin Wang; Jacqueline T. Johanas; Gary G. Leisk; David L. Kaplan (pp. 3213-3223).
Tissue engineering is an alternative approach for the preparation of small-diameter (<6mm) vascular grafts due to the potential to control thrombosis, anastomotic cellular hyperplasia and matrix production. This control also requires the maintenance of graft patency in vivo, appropriate mechanical properties and the formation of a functional endothelium. As a first step in generating such tissue-engineered vascular grafts (TEVGs), our objective was to develop a tissue-engineered construct that mimicked the structure of blood vessels using tubular electrospun silk fibroin scaffolds (ESFSs) with suitable mechanical properties. Human coronary artery smooth muscle cells (HCASMCs) and human aortic endothelial cells (HAECs) were sequentially seeded onto the luminal surface of the tubular scaffolds and cultivated under physiological pulsatile flow. The results demonstrated that TEVGs under dynamic flow conditions had better outcome than static culture controls in terms of cell proliferation and alignment, ECM production and cell phenotype based on transcript and protein level assessments. The metabolic activity of HCASMCs present in the TEGs indicated the advantage of dynamic flow over static culture in effective nutrient and oxygen distribution to the cells. A matrigel coating as a basement membrane mimic for ECM significantly improved endothelium coverage and retention under physiological shear forces. The results demonstrate the successful integration of vascular cells into silk electrospun tubular scaffolds as a step toward the development of a TEVG similar to native vessels in terms of vascular cell outcomes and mechanical properties.
Keywords: Silk; Electrospinning; Endothelial cells; Smooth muscle cells; Vascular graft
Chest wall reconstruction in a canine model using polydioxanone mesh, demineralized bone matrix and bone marrow stromal cells
by Hua Tang; Zhifei Xu; Xiong Qin; Bin Wu; Lihui Wu; XueWei Zhao; Yulin Li (pp. 3224-3233).
Extensive chest wall defect reconstruction remains a challenging problem for surgeons. In the past several years, little progress has been made in this area. In this study, a biodegradable polydioxanone (PDO) mesh and demineralized bone matrix (DBM) seeded with osteogenically induced bone marrow stromal cells (BMSCs) were used to reconstruct a 6cm×5.5cm chest wall defect. Four experimental groups were evaluated ( n=6 per group): polydioxanone (PDO) mesh/DBMs/BMSCs group, polydioxanone (PDO) mesh/DBMs group, polydioxanone (PDO) mesh group, and a blank group (no materials) in a canine model. All the animals survived except those in the blank group. In all groups receiving biomaterial implants, the polydioxanone (PDO) mesh completely degraded at 24 weeks and was replaced by fibrous tissue with thickness close to that of the normal intercostal tissue ( P>0.05). In the polydioxanone (PDO) mesh/DBMs/BMSCs group, new bone formation and bone-union were observed by radiographic and histological examination. More importantly, the reconstructed rib could maintain its original radian and achieve satisfactory biomechanics close to normal ribs in terms of bending stress ( P>0.05). However, in the other two groups, fibrous tissue was observed in the defect and junctions, and the reconstructed ribs were easily distorted under an outer force. Based on these results, a surgical approach utilizing biodegradable polydioxanone (PDO) mesh in combination with DBMs and BMSCs could repair the chest wall defect not only in function but also in structure.
Keywords: Chest wall; Tissue engineering; PDO; DBM; BMSCs; Canine model
Repair of infarcted myocardium using mesenchymal stem cell seeded small intestinal submucosa in rabbits
by Mei Yun Tan; Wei Zhi; Ren Qian Wei; Yong Can Huang; Kun Peng Zhou; Bo Tan; Li Deng; Jing Cong Luo; Xiu Qun Li; Hui Qi Xie; Zhi Ming Yang (pp. 3234-3240).
Myocardial infarction (MI) remains a common and deadly disease. Using tissue-engineered cardiac grafts to repair infarcted myocrdium is considered to be a therapeutic approach. This study tested the feasibility of using MSCs-seeded SIS to repair chronic myocardial infarction in a rabbit model. MI in rabbits was created by ligation of the left anterior descending artery. BrdU-labeled mesenchymal stem cells (MSCs) were seeded on the small intestinal submucosa and cultured for 5–7 days prior to implantation. Four weeks after myocardial infarction, cardiac grafts were implanted onto the epicardial surface of infarcted myocardium. Four weeks after implantation of the membranes, a serial of tests including echocardiography, hemodynamics, histology and immunohistochemistry were undertaken to evaluate the effect of the implanted grafts on recovery of the infarcted myocardium. It was shown that left ventricular contractile function and dimension, the capillary density of the infarcted region, and myocardial pathological changes were significantly improved in rabbits implanted either SIS or MSCs-seeded SIS. But the MSCs-seeded SIS was more effective. Immunofluorescence staining demonstrated the migration of Brdu-labeled MSCs from the membrane into the infarcted area and their differentiation to cardiomyocytes and smooth muscle cells. Taken together, these results suggest that MSCs-seeded SIS can be used to repair chronic myocardial infarction, which enhances myocardial regeneration.
Keywords: Myocardial infarction; Mesenchymal stem cells; Small intestinal submucosa; Tissue engineering
In vitro engineering of fibrocartilage using CDMP1 induced dermal fibroblasts and polyglycolide
by Guiqing Zhao; Shuo Yin; Guangpeng Liu; Lian Cen; Jian Sun; Heng Zhou; Wei Liu; Lei Cui; Yilin Cao (pp. 3241-3250).
This study was designed to explore the feasibility of using cartilage-derived morphogenetic protein-1 (CDMP1) induced dermal fibroblasts (DFs) as seed cells and polyglycolide (PGA) as scaffold for fibrocartilage engineering. DFs isolated from canine were expanded and seeded on PGA scaffold to fabricate cell/scaffold constructs which were cultured with or without CDMP1. Proliferation and differentiation of DFs in different constructs were determined by DNA assay and glycosaminoglycan (GAG) production. Histological and immunohistochemical staining of the constructs after being in vitro cultured for 4 and 6 weeks were carried out to observe the fibrocartilage formation condition. The fibrocartilage-specific gene expression by cells in the constructs was analyzed by real-time PCR. It was shown that in the presence of CDMP1 the proliferation and GAG synthesis of DFs were significantly enhanced compared to those without CDMP1. Fibrocartilage-like tissue was formed in the CDMP1 induced construct after being cultured for 4 weeks, and it became more matured at 6 weeks as stronger staining for GAG and higher gene expression of collagen type II was observed. Since only weak staining for GAG and collagen type II was observed for the construct engineered without CDMP1, the induction effect on the fibrocartilage engineering can be ascertained when using DFs as seed cells. Furthermore, the potential of using DFs as seed cells to engineer fibrocartilage is substantiated and further study on using the engineered tissue to repair fibrocartilage defects is currently ongoing in our group.
Keywords: Cartilage-derived morphogenetic protein-1; Dermal fibroblasts; Fibrocartilage; Tissue engineering
Differentiation of bone marrow-derived mesenchymal stem cells into multi-layered epidermis-like cells in 3D organotypic coculture
by Kun Ma; Filip Laco; Seeram Ramakrishna; Susan Liao; Casey K. Chan (pp. 3251-3258).
The interactions of bone marrow-derived mesenchymal stem cells (MSCs) and their engrafted microenvironment are an integral part of signaling control of stem cell lineage commitment. We attempted to induce bone marrow-derived MSCs to undergo epidermal lineage differentiation by manipulating the biochemical, environmental and physical properties of culture conditions in an organotypic coculture model to simulate a skin-specific microenvironment. The induction medium was optimized by varying different biomolecular supplements in a basic stratification medium. A multi-layered epidermis-like structure was established when MSCs were cultured in an optimized induction medium on a contractible fibroblast-embedded collagen gel with an air–liquid interface. The commitment into epidermal lineage was further confirmed by the expression of early and intermediate epidermalization markers – keratin 10 and filaggrin in 90.67% and 80.51% of MSCs, respectively. This study not only highlights the possibility of in vitro control of MSCs into epidermal lineage, but also suggests the therapeutic potential of bone marrow-derived MSCs for skin regeneration.
Keywords: Mesenchymal stem cells; Epidermal differentiation; Organotypic coculture; Skin regeneration
Urinary bladder smooth muscle engineered from adipose stem cells and a three dimensional synthetic composite
by Gregory S. Jack; Rong Zhang; Min Lee; Yuhan Xu; Ben M. Wu; Larissa V. Rodríguez (pp. 3259-3270).
Human adipose stem cells were cultured in smooth muscle inductive media and seeded into synthetic bladder composites to tissue engineer bladder smooth muscle. 85:15 Poly-lactic-glycolic acid bladder dome composites were cast using an electropulled microfiber luminal surface combined with an outer porous sponge. Cell-seeded bladders expressed smooth muscle actin, myosin heavy chain, calponinin, and caldesmon via RT-PCR and immunoflourescence. Nude rats ( n=45) underwent removal of half their bladder and repair using: (i) augmentation with the adipose stem cell-seeded composites, (ii) augmentation with a matched acellular composite, or (iii) suture closure. Animals were followed for 12 weeks post-implantation and bladders were explanted serially. Results showed that bladder capacity and compliance were maintained in the cell-seeded group throughout the 12 weeks, but deteriorated in the acellular scaffold group sequentially with time. Control animals repaired with sutures regained their baseline bladder capacities by week 12, demonstrating a long-term limitation of this model. Histological analysis of explanted materials demonstrated viable adipose stem cells and increasing smooth muscle mass in the cell-seeded scaffolds with time. Tissue bath stimulation demonstrated smooth muscle contraction of the seeded implants but not the acellular implants after 12 weeks in vivo. Our study demonstrates the feasibility and short term physical properties of bladder tissue engineered from adipose stem cells.
Keywords: Stem cell; Smooth muscle cell; Urinary tract; Organ culture; Bladder tissue engineering
The effect of the co-immobilization of human osteoprogenitors and endothelial cells within alginate microspheres on mineralization in a bone defect
by Maritie Grellier; Pedro L. Granja; Jean-Christophe Fricain; Sílvia J. Bidarra; Martine Renard; Reine Bareille; Chantal Bourget; Joelle Amédée; Mário A. Barbosa (pp. 3271-3278).
Bone regeneration seems to be dependant on cell communication between osteogenic and endothelial cells arising from surrounding blood vessels. This study aims to determine whether endothelial cells can regulate the osteogenic potential of osteoprogenitor cells in vitro and in vivo, in a long bone defect, when co-immobilized in alginate microspheres. Alginate is a natural polymer widely used as a biomaterial for cell encapsulation. Human osteoprogenitors (HOP) from bone marrow mesenchymal stem cells were immobilized alone or together with human umbilical vein endothelial cells (HUVEC) inside irradiated, oxidized and RGD-grafted alginate microspheres. Immobilized cells were cultured in dynamic conditions and cell metabolic activity increased during three weeks. The gene expression of alkaline phosphatase and osteocalcin, both specific markers of the osteoblastic phenotype, and mineralization deposits were upregulated in co-immobilized HOPs and HUVECs, comparing to the immobilization of monocultures. VEGF secretion was also increased when HOPs were co-immobilized with HUVECs. Microspheres containing co-cultures were further implanted in a bone defect and bone formation was analysed by μCT and histology at 3 and 6 weeks post-implantation. Mineralization was observed inside and around the implanted microspheres containing the immobilized cells. However, when HOPs were co-immobilized with HUVECs, mineralization significantly increased. These findings demonstrate that co-immobilization of osteogenic and endothelial cells within RGD-grafted alginate microspheres provides a promising strategy for bone tissue engineering.
Keywords: Osteoprogenitors; Endothelial cells; Co-culture; Alginate; Cell immobilization; Vascular endothelial growth factor (VEGF)
The effect of dual frequency cyclic compression on matrix deposition by osteoblast-like cells grown in 3D scaffolds and on modulation of VEGF variant expression
by Virginie Dumas; Anthony Perrier; Luc Malaval; Norbert Laroche; Alain Guignandon; Laurence Vico; Aline Rattner (pp. 3279-3288).
As a strategy to optimise osteointegration of biomaterials by inducing proper extracellular matrix synthesis, and specifically angiogenic growth factor production and storage, we tested the effects of cyclic mechanical compression on 3D cultures of human osteoblast-like cells. MG-63 cells were seeded into 3D porous hydroxyapatite ceramics under vacuum to enable a homogenous cellular distribution. A four-day culture period allowed cell proliferation throughout the scaffolds. Low amplitude cyclic compressions were then applied to the scaffolds for 15min with different regimens generated by the ZetOS™ system. A 3Hz sinusoidal (sine) signal increased slightly collagen and fibronectin expression. When 50Hz or 100Hz vibrations were superimposed to the 3Hz signal, matrix protein expression was down-regulated. In contrast, adding a 25Hz vibration up-regulated significantly collagen and fibronectin. Moreover, expression of a matrix-bound variant of vascular endothelial growth factor-A (VEGF-A) was specifically stimulated compared to control or 3Hz sine, and non-soluble VEGF protein was increased. Our study enabled us to identify low-amplitude, high-frequency strain regimen able to increase major matrix proteins of bone tissue and to regulate the expression of VEGF variants, showing that an appropriate combined loading has the potential to functionalise cellularized bone-like constructs.
Keywords: Bone tissue engineering/osseointegration; Osteoblast; ECM (extracellular matrix); Growth factors; Hydroxyapatite; Mechanical test/strain rate
Engineering thermoresponsive polymeric nanoshells
by Daniel Cohn; Hagit Sagiv; Alexandra Benyamin; Gilad Lando (pp. 3289-3296).
This study describes a family of hollow nanoscale constructs able to display a large and reversible change in size, within a narrow temperature interval. These thermoresponsive nanostructures are generated by crosslinking functionalized amphiphilic molecules, such as poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblocks, while constrained to their particular micellar configuration. This contribution focuses on the generation of these supramolecular architectures, by intra-micellarly crosslinking PEO–PPO–PEO dimethacrylate amphiphiles, and investigates their temperature-dependent dimensional behavior. Spherical nanoshells displaying a 200nm diameter at 15°C, shrink sharply around 28°C, generating a compact structure of approximately 40nm at body temperature. Thermoresponsive nanotubes were created by generating them from rod-like micelles at higher temperatures. By varying the composition of the triblock, the transition temperature can be fine tuned, from around 25°C to slightly above body temperature. Also, the nanoshells were rendered biodegradable by incorporating aliphatic oligoesters into their structure. Numerous applications for these nanostructures are foreseen in various biomedical areas, such as in drug and gene delivery, in the tissue engineering and in the biosensors field.
Keywords: Thermoresponsive polymer; Nanoparticle; Degradation; Crosslinking; Pluronics
Poly(lactide)–vitamin E derivative/montmorillonite nanoparticle formulations for the oral delivery of Docetaxel
by Si-Shen Feng; Lin Mei; Panneerselvan Anitha; Chee Wee Gan; Wenyou Zhou (pp. 3297-3306).
Four systems of nanoparticles of biodegradable polymers were developed in this research for oral delivery of anticancer drugs with Docetaxel used as a model drug, which include the poly(lactic- co-glycolic acid) nanoparticles (PLGA NPs), the poly(lactide)–vitamin E TPGS nanoparticles (PLA–TPGS NPs), the poly(lactic- co-glycolic acid)–montmorillonite nanoparticles (PLGA/MMT NPs) and the poly(lactide)–vitamin E TPGS/montmorillonite nanoparticles (PLA–TPGS/MMT NPs). Vitamin E TPGS stands for d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), which is a water-soluble derivative of natural vitamin E formed by esterification of vitamin E succinate with polyethylene glycol (PEG) 1000. The design was made to take advantages of TPGS in nanoparticle technology such as high emulsification effects and high drug encapsulation efficiency, and those in drug formulation such as high cellular adhesion and adsorption. MMT of similar effects is also a detoxifier, which may cure some side effects caused by the formulated drug. The drug-loaded NPs were prepared by a modified solvent extraction/evaporation method and then characterized for their MMT content, size and size distribution, surface charge and morphology, physical status and encapsulation efficiency of the drug in the NPs, and in vitro drug release profile. Cellular uptake of the coumarin 6-loaded NPs was investigated. In vitro cancer cell viability experiment showed that judged by IC50, the PLA–TPGS/MMT NP formulation was found 2.89, 3.98, 2.12-fold more effective and the PLA–TPGS NP formulation could be 1.774, 2.58, 1.58-fold more effective than the Taxotere® after 24, 48, 72h treatment, respectively. In vivo PK experiment with SD rats showed that oral administration of the PLA–TPGS/MMT NP formulation and the PLA–TPGS NP formulation could achieve 26.4 and 20.6 times longer half-life respectively than i.v. administration of Taxotere® at the same 10mg/kg dose. One dose oral administration of the NP formulations could realize almost 3 week sustained chemotherapy in comparison of 22h of i.v. administration of Taxotere®. The oral bioavailability can be enhanced from 3.59% for Taxotere® to 78% for the PLA–TPGS/MMT NP formulation and 91% for the PLA–TPGS NP formulation respectively. Oral chemotherapy by nanoparticles of biodegradable polymers is feasible.
Keywords: Anticancer drugs; Biodegradable polymers; Cancer nanotechnology; Drug delivery device; Oral chemotherapy; Medical clay
Hydroxyapatite nano and microparticles: Correlation of particle properties with cytotoxicity and biostability
by M. Motskin; D.M. Wright; K. Muller; N. Kyle; T.G. Gard; A.E. Porter; J.N. Skepper (pp. 3307-3317).
Synthetic colloid and gel hydroxyapatite (HA) nanoparticles (NPs) were spray dried to form microparticles (MPs). These are intended for use as slow release vaccine vectors. The physico-chemical properties of gel and colloid NPs and MPs were compared to those of HA obtained commercially. Their cytotoxicity to human monocytes'-derived macrophages (HMMs) was assessed in vitro using a range of techniques. These included the MTT assay, LDH leakage and a confocal based live–dead cell assay. Cytotoxicity differed significantly between preparations, with the suspended gel preparation being the most toxic (31–500μg/ml). Other preparations were also toxic but only at higher concentrations (>250μg/ml). Transmission electron microscopy (TEM) and stereology showed variable cellular uptake and subsequent dissolution of the various forms of HA. We have demonstrated that HA particle toxicity varied considerably and that it was related to their physico-chemical properties. Cell death correlated strongly with particle load. The intracellular dissolution of particles as a function of time in HMM suggests that increased cytoplasmic calcium load is likely to be the cause of cell death. Some HA NPs eluded the phagocytic pathway and a few were even seen to enter the nuclei through nuclear pores.
Keywords: Hydroxyapatite; Nanoparticles; Cytotoxicity; Slow release; Vaccine delivery; Transfection
The augmentation of intracellular delivery of peptide therapeutics by artificial protein transduction domains
by Tomoaki Yoshikawa; Toshiki Sugita; Yohei Mukai; Yasuhiro Abe; Shinsaku Nakagawa; Haruhiko Kamada; Shin-ichi Tsunoda; Yasuo Tsutsumi (pp. 3318-3323).
Protein transduction domains (PTDs), such as HIV-derived Tat, have been successfully used as functional biomaterials for intracellular delivery of anti-cancer macromolecular drugs (protein, peptides, and oligonucleotides). Although there were therefore great expectations regarding the therapeutic potential of PTDs for the development of anti-cancer therapeutics, their clinical application so far has been extremely limited because of the relatively high concentrations required to mediate any effects on cancer cells in vitro or in vivo. In this context, improving the transduction efficiency of PTDs using phage display-based molecular evolution techniques may be useful for creating artificial PTDs with high efficiency and safety. Here, we report an evaluation of transduction efficiency and toxicity of such artificial PTDs (designated mT02 and mT03) compared with Tat. The internalization of mT02 was the most rapid and efficient by a mechanism different from the usual macropinocytosis. Furthermore, we found that artificial PTDs fused with survivin antagonistic peptide potentiate tumor cell-cytostatic activity. Thus, the results of this work provide new insights for designing new-generation peptide therapeutics for a wide variety of cancers as well as those expressing survivin.
Keywords: Peptide; Protein transduction domain (PTD); Intracellular delivery; Phage display
Calcium phosphate nanoparticles as efficient carriers for photodynamic therapy against cells and bacteria
by J. Schwiertz; A. Wiehe; S. Gräfe; B. Gitter; M. Epple (pp. 3324-3331).
Calcium phosphate nanoparticles were surface-functionalized with different polymers, and photosensitizers were incorporated into this layer. The charge was adjusted by choosing the appropriate polymer. Methylene blue and 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin ( mTHPP) were used as photosensitizers. The particles showed a good performance with HIG-82 synoviocytes. For J774A.1 macrophages, they were toxic also in the dark, probably due to a lethal uptake of calcium. For HT29 epithelial cells, a moderate activity was observed. A good photoxicity was observed against the bacterial strain Staphylococcus aureus (Gram-positive), both with positively and negatively charged nanoparticles loaded with mTHPP. Against Pseudomonas aeruginosa (Gram-negative), good photoxicity was observed only with positively charged nanoparticles loaded with mTHPP. At higher concentrations, methylene blue-loaded nanoparticles were active against S. aureus. Thus, it is possible to prepare a water-dispersable system of dye-loaded calcium phosphate nanoparticles, but the efficiency depends on a number of parameters, e.g. particle charge, kind of polymer, and cell culture medium (e.g. the presence of proteins).
Keywords: Calcium phosphate; Nanoparticles; Photodynamic therapy; Porphyrins; Polymers
Development of pH-responsive chitosan/heparin nanoparticles for stomach-specific anti- Helicobacter pylori therapy
by Yu-Hsin Lin; Chiung-Hung Chang; Yu-Shiun Wu; Yuan-Man Hsu; Shu-Fen Chiou; Yi-Jen Chen (pp. 3332-3342).
The microorganism now known as Helicobacter pylori is considered to be an important factor in the etiology of peptic ulcers. It can secrete urease enzyme and buffer gastric acids to survive in the stomach. H. pylori can colonize the gastric mucosa and preferentially adheres near the cell–cell junctions of the gastric mucous cells. In this study, pH-responsive nanoparticles were produced instantaneously upon the addition of heparin solution to a chitosan solution with magnetic stirring at room temperature. The nanoparticles appeared to have a particle size of 130–300nm, with a positive surface charge, and were stable at pH 1.2–2.5, allowing them to protect an incorporated drug from destructive gastric acids. We also demonstrated that the prepared nanoparticles can adhere to and infiltrate cell–cell junctions and interact locally with H. pylori infection sites in intercellular spaces.
Keywords: Chitosan; Heparin; Peptic ulcers; Helicobacter pylori; Intercellular spaces
Magnetically targeted thrombolysis with recombinant tissue plasminogen activator bound to polyacrylic acid-coated nanoparticles
by Yunn-Hwa Ma; Siao-Yun Wu; Tony Wu; Yeu-Jhy Chang; Mu-Yi Hua; Jyh-Ping Chen (pp. 3343-3351).
We investigated the feasibility and efficacy of target thrombolysis with recombinant tissue plasminogen activator (rtPA) covalently bound to magnetic nanoparticle (MNP) and retained to the target site in vivo by an external magnet. Polyacrylic acid-coated magnetite (PAA–MNP, 246nm) was synthesized and characterized; rtPA was immobilized to PAA–MNP through carbodiimide-mediated amide bond formation. The enzyme activities of the bound rtPA, as measured by a chromogenic substrate assay and125I-fibrinolysis assay, were 87±1% and 86±3% of that of free rtPA. Under guidance with the magnet moving back and forth along the iliac artery, the thrombolytic activity of PAA–MNP–rtPA with rtPA equivalent to 0.2mg/kg was determined by flowmetry in a rat embolic model. Intra-arterial administration of PAA–MNP–rtPA restored the iliac blood flow within 75min to 82% of that before the clot lodging, whereas equivalent amount of PAA–MNP or free rtPA exerted no improvement on hemodynamics. At the end of 2-h period, PAA–MNP–rtPA did not alter levels of hemoglobin, hematocrit, or blood cell count. In conclusion, immobilization of rtPA to PAA–MNP with covalent binding resulted in a stable rtPA preparation and predictable amount of rtPA around the target site under magnetic guidance; this approach may achieve reproducible and effective target thrombolysis with <20% of a regular dose of rtPA.
Keywords: Embolism; Thrombolysis; Fibrinolysis; Tissue plasminogen activator; Nanoparticle
Development of polyion complex micelles for encapsulating and delivering amphotericin B
by Chau-Hui Wang; Wei-Ting Wang; Ging-Ho Hsiue (pp. 3352-3358).
A block copolymer poly(2-ethyl-2-oxazoline)- block-poly(aspartic acid) (PEOz- b-PAsp) was synthesized and investigated as the carrier of antifungal drug amphotericin B (AmB). Polyion complex (PIC) micelles with clear core–shell structures were identified by TEM, which revealed that the PAsp segment became hydrophobic after it interacted with AmB. PEOz- b-PAsp increased not only the solubility of AmB but also simultaneously the drug potency. The prolonged release of AmB from micelles effectively inhibited the growth of Candida albicans even after three days of administration. Moreover, the in vitro cytotoxicity of AmB-loaded micelles was less than that of Fungizone®, which is a powerful antifungal antibiotic that is adopted to treat various fungal infections. The PEOz- b-PAsp PIC micelles with lower cytotoxicity and higher potency than Fungizone® represent a potential means of encapsulating basic/amphoteric drugs.
Keywords: Amphotericin B; Poly(2-ethyl-2-oxazoline); Poly(aspartic acid); Polyion complex micelles