Polymers

Editorial

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Open AccessEditorial

Advanced Control over Cell-Material Interfaces

by João F. Mano and Insung S. Choi

Polymers 2017, 9(12), 704; https://doi.org/10.3390/polym9120704 - 12 Dec 2017

Cited by 2 | Viewed by 3348

Abstract

Cells in vivo sense and respond to signals from their environment (e.g., other cells and extracellular matrices) for their orchestrated behaviour and function.[...] Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

Research

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17 pages, 7136 KiB

Open AccessArticle

Surface Hydrophilicity of Poly(l-Lactide) Acid Polymer Film Changes the Human Adult Adipose Stem Cell Architecture

by Chiara Argentati, Francesco Morena, Pia Montanucci, Marco Rallini, Giuseppe Basta, Nicolino Calabrese, Riccardo Calafiore, Marino Cordellini, Carla Emiliani, Ilaria Armentano and Sabata Martino

Polymers 2018, 10(2), 140; https://doi.org/10.3390/polym10020140 - 1 Feb 2018

Cited by 26 | Viewed by 6010

Abstract

Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide) acid (PLLA) polymer film and [...] Read more.

Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide) acid (PLLA) polymer film and human adult adipose stem cells (hASCs), focusing on the events correlating the materials’ surface characteristics and the cells’ plasma membrane. hASCs were seeded on films of pristine PLLA polymer and on a PLLA surface modified by the radiofrequency plasma method under oxygen flow (PLLA+O₂). Comparative experiments were performed using human bone-marrow mesenchymal stem cells (hBM-MSCs) and human umbilical matrix stem cells (hUCMSCs). After treatment with oxygen-plasma, the surface of PLLA films became hydrophilic, whereas the bulk properties were not affected. hASCs cultured on pristine PLLA polymer films acquired a spheroid conformation. On the contrary, hASCs seeded on PLLA+O₂ film surface maintained the fibroblast-like morphology typically observed on tissue culture polystyrene. This suggests that the surface hydrophilicity is involved in the acquisition of the spheroid conformation. Noteworthy, the oxygen treatment had no effects on hBM-MSC and hUCMSC cultures and both stem cells maintained the same shape observed on PLLA films. This different behavior suggests that the biomaterial-interaction is stem cell specific. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Incorporation of Calcium Containing Mesoporous (MCM-41-Type) Particles in Electrospun PCL Fibers by Using Benign Solvents

by Liliana Liverani, Elena Boccardi, Ana Maria Beltrán and Aldo R. Boccaccini

Polymers 2017, 9(10), 487; https://doi.org/10.3390/polym9100487 - 4 Oct 2017

Cited by 29 | Viewed by 6613

Abstract

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2 particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The [...] Read more.

The electrospinning technique is a versatile method for the production of fibrous scaffolds able to resemble the morphology of the native extra cellular matrix. In the present paper, electrospinning is used to fabricate novel SiO2 particles (type MCM-41) containing poly(epsilon-caprolactone) (PCL) fibers. The main aims of the present work are both the optimization of the particle synthesis and the fabrication of composite fibers, obtained using benign solvents, suitable as drug delivery systems and scaffolds for soft tissue engineering applications. The optimized synthesis and characterization of calcium-containing MCM-41 particles are reported. Homogeneous bead-free composite electrospun mats were obtained by using acetic acid and formic acid as solvents; neat PCL electrospun mats were used as control. Initially, an optimization of the electrospinning environmental parameters, like relative humidity, was performed. The obtained composite nanofibers were characterized from the morphological, chemical and mechanical points of view, the acellular bioactivity of the composite nanofibers was also investigated. Positive results were obtained in terms of mesoporous particle incorporation in the fibers and no significant differences in terms of average fiber diameter were detected between the neat and composite electrospun fibers. Even if the Ca-containing MCM-41 particles are bioactive, this property is not preserved in the composite fibers. In fact, during the bioactivity assessment, the particles were released confirming the potential application of the composite fibers as a drug delivery system. Preliminary in vitro tests with bone marrow stromal cells were performed to investigate cell adhesion on the fabricated composite mats, the positive obtained results confirmed the suitability of the composite fibers as scaffolds for soft tissue engineering. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Osteogenesis of Adipose-Derived and Bone Marrow Stem Cells with Polycaprolactone/Tricalcium Phosphate and Three-Dimensional Printing Technology in a Dog Model of Maxillary Bone Defects

by Jeong Woo Lee, Seung Gyun Chu, Hak Tae Kim, Kang Young Choi, Eun Jung Oh, Jin-Hyung Shim, Won-Soo Yun, Jung Bo Huh, Sung Hwan Moon, Seong Soo Kang and Ho Yun Chung

Polymers 2017, 9(9), 450; https://doi.org/10.3390/polym9090450 - 15 Sep 2017

Cited by 25 | Viewed by 7213

Abstract

Bone graft material should possess sufficient porosity and permeability to allow integration with native tissue and vascular invasion, and must satisfy oxygen and nutrient transport demands. In this study, we have examined the use of three-dimensional (3D)-printed polycaprolactone/tricalcium phosphate (PCL/TCP) composite material in [...] Read more.

Bone graft material should possess sufficient porosity and permeability to allow integration with native tissue and vascular invasion, and must satisfy oxygen and nutrient transport demands. In this study, we have examined the use of three-dimensional (3D)-printed polycaprolactone/tricalcium phosphate (PCL/TCP) composite material in bone grafting, to estimate the scope of its potential application in bone surgery. Adipose-derived stem cells (ADSCs) and bone marrow stem cells (BMSCs) are known to enhance osteointegration. We hypothesized that a patient-specific 3D-printed solid scaffold could help preserve seeded ADSCs and BMSCs and enhance osteointegration. Diffuse osteogenic tissue formation was observed by micro-computed tomography with both stem cell types, and the ADSC group displayed similar osteogenesis compared to the BMSC group. In histological assessment, the scaffold pores showed abundant ossification in both groups. Reverse transcription polymerase chain reaction (RT-PCR) showed that the BMSC group had higher expression of genes associated with ossification, and this was confirmed by Western blot analysis. The ADSC- and BMSC-seeded 3D-printed PCL/TCP scaffolds displayed promising enhancement of osteogenesis in a dog model of maxillary bone defects. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

In Vitro and in Vivo Study of Poly(Lactic–co–Glycolic) (PLGA) Membranes Treated with Oxygen Plasma and Coated with Nanostructured Hydroxyapatite Ultrathin Films for Guided Bone Regeneration Processes

by Daniel Torres-Lagares, Lizett Castellanos-Cosano, María Ángeles Serrera-Figallo, Francisco J. García-García, Carmen López-Santos, Angel Barranco, Agustín Rodríguez-Gonzalez Elipe, Cristóbal Rivera-Jiménez and José-Luis Gutiérrez-Pérez

Polymers 2017, 9(9), 410; https://doi.org/10.3390/polym9090410 - 2 Sep 2017

Cited by 10 | Viewed by 6342

Abstract

The novelty of this study is the addition of an ultrathin layer of nanostructured hydroxyapatite (HA) on oxygen plasma modified poly(lactic–co–glycolic) (PLGA) membranes (PO₂) in order to evaluate the efficiency of this novel material in bone regeneration. Methods: Two [...] Read more.

The novelty of this study is the addition of an ultrathin layer of nanostructured hydroxyapatite (HA) on oxygen plasma modified poly(lactic–co–glycolic) (PLGA) membranes (PO₂) in order to evaluate the efficiency of this novel material in bone regeneration. Methods: Two groups of regenerative membranes were prepared: PLGA (control) and PLGA/PO₂/HA (experimental). These membranes were subjected to cell cultures and then used to cover bone defects prepared on the skulls of eight experimental rabbits. Results: Cell morphology and adhesion of the osteoblasts to the membranes showed that the osteoblasts bound to PLGA were smaller and with a lower number of adhered cells than the osteoblasts bound to the PLGA/PO₂/HA membrane (p < 0.05). The PLGA/PO₂/HA membrane had a higher percentage of viable cells bound than the control membrane (p < 0.05). Both micro-CT and histological evaluation confirmed that PLGA/PO₂/HA membranes enhance bone regeneration. A statistically significant difference in the percentage of osteoid area in relation to the total area between both groups was found. Conclusions: The incorporation of nanometric layers of nanostructured HA into PLGA membranes modified with PO₂ might be considered for the regeneration of bone defects. PLGA/PO₂/HA membranes promote higher osteosynthetic activity, new bone formation, and mineralisation than the PLGA control group. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Effect of Catechol Content in Catechol-Conjugated Dextrans on Antiplatelet Performance

by Yeonwoo Jeong, Kwang-A Kim and Sung Min Kang

Polymers 2017, 9(8), 376; https://doi.org/10.3390/polym9080376 - 19 Aug 2017

Cited by 4 | Viewed by 5828

Abstract

The surface coating of solid substrates using dextrans has gained a great deal of attention, because dextran-coated surfaces show excellent anti-fouling property as well as biocompatibility behavior. Much effort has been made to develop efficient methods for grafting dextrans on solid surfaces. This [...] Read more.

The surface coating of solid substrates using dextrans has gained a great deal of attention, because dextran-coated surfaces show excellent anti-fouling property as well as biocompatibility behavior. Much effort has been made to develop efficient methods for grafting dextrans on solid surfaces. This led to the development of catechol-conjugated dextrans (Dex-C) which can adhere to a number of solid surfaces, inspired by the underwater adhesion behavior of marine mussels. The present study is a systematic investigation of the characteristics of surface coatings developed with Dex-C. Various Dex-C with different catechol contents were synthesized and used as a surface coating material. The effect of catechol content on surface coating and antiplatelet performance was investigated. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Enhanced Cartilaginous Tissue Formation with a Cell Aggregate-Fibrin-Polymer Scaffold Complex

by Soojin Lee, Kangwon Lee, Soo Hyun Kim and Youngmee Jung

Polymers 2017, 9(8), 348; https://doi.org/10.3390/polym9080348 - 8 Aug 2017

Cited by 13 | Viewed by 6796

Abstract

Cell density is one of the factors required in the preparation of engineered cartilage from mesenchymal stem cells (MSCs). Additionally, it is well known for having a significant role in chemical and physical stimulations when stem cells undergo chondrogenic differentiation. Here, we developed [...] Read more.

Cell density is one of the factors required in the preparation of engineered cartilage from mesenchymal stem cells (MSCs). Additionally, it is well known for having a significant role in chemical and physical stimulations when stem cells undergo chondrogenic differentiation. Here, we developed an engineered cartilage with a cell aggregate-hydrogel-polymer scaffold complex capable of inducing the effective regeneration of cartilage tissue similar to natural cartilage while retaining a high mechanical strength, flexibility, and morphology. Cell aggregates were generated by the hanging drop method with rabbit bone marrow stromal cells (BMSCs), and poly (lactide-co-caprolactone) (PLCL) scaffolds were fabricated with 78.3 ± 5.3% porosity and a 300–500 μm pore size with a gel-pressing method. We prepared the cell aggregate-fibrin-poly (lactide-co-caprolactone) (PLCL) scaffold complex, in which the cell aggregates were evenly dispersed in the fibrin, and they were immobilized onto the surface of the polymer scaffold while filling up the pores. To examine the chondrogenic differentiation of seeded BMSCs and the formation of chondral extracellular matrix onto the complexes, they were cultured in vitro or subcutaneously implanted into nude mice for up to eight weeks. The results of the in vitro and in vivo studies revealed that the accumulation of the chondral extracellular matrices was increased on the cell aggregate-fibrin-PLCL scaffold complexes (CAPs) compared to the single cell-fibrin-PLCL scaffold complexes (SCPs). Additionally, we examined whether the mature and well-developed cartilaginous tissues and lacunae structures typical of mature cartilage were evenly distributed in the CAPs. Consequently, the cell aggregates in the hybrid scaffolds of fibrin gels and elastic PLCL scaffolds can induce themselves to differentiate into chondrocytes, maintain their phenotypes, enhance glycosaminoglycan (GAG) production, and improve the quality of cartilaginous tissue formed in vitro and in vivo. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Electrospinning PCL Scaffolds Manufacture for Three-Dimensional Breast Cancer Cell Culture

by Marc Rabionet, Marc Yeste, Teresa Puig and Joaquim Ciurana

Polymers 2017, 9(8), 328; https://doi.org/10.3390/polym9080328 - 1 Aug 2017

Cited by 66 | Viewed by 10778

Abstract

In vitro cell culture is traditionally performed within two-dimensional (2D) environments, providing a quick and cheap way to study cell properties in a laboratory. However, 2D systems differ from the in vivo environment and may not mimic the physiological cell behavior realistically. For [...] Read more.

In vitro cell culture is traditionally performed within two-dimensional (2D) environments, providing a quick and cheap way to study cell properties in a laboratory. However, 2D systems differ from the in vivo environment and may not mimic the physiological cell behavior realistically. For instance, 2D culture models are thought to induce cancer stem cells (CSCs) differentiation, a rare cancer cell subpopulation responsible for tumor initiation and relapse. This fact hinders the development of therapeutic strategies for tumors with a high relapse percentage, such as triple negative breast cancer (TNBC). Thus, three-dimensional (3D) scaffolds have emerged as an attractive alternative to monolayer culture, simulating the extracellular matrix structure and maintaining the differentiation state of cells. In this work, scaffolds were fabricated through electrospinning different poly(ε-caprolactone)-acetone solutions. Poly(ε-caprolactone) (PCL) meshes were seeded with triple negative breast cancer (TNBC) cells and 15% PCL scaffolds displayed significantly (p < 0.05) higher cell proliferation and elongation than the other culture systems. Moreover, cells cultured on PCL scaffolds exhibited higher mammosphere forming capacity and aldehyde dehydrogenase activity than 2D-cultured cells, indicating a breast CSCs enrichment. These results prove the powerful capability of electrospinning technology in terms of poly(ε-caprolactone) nanofibers fabrication. In addition, this study has demonstrated that electrospun 15% PCL scaffolds are suitable tools to culture breast cancer cells in a more physiological way and to expand the niche of breast CSCs. In conclusion, three-dimensional cell culture using PCL scaffolds could be useful to study cancer stem cell behavior and may also trigger the development of new specific targets against such malignant subpopulation. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Manipulating Living Cells to Construct a 3D Single-Cell Assembly without an Artificial Scaffold

by Aoi Yoshida, Shoto Tsuji, Hiroaki Taniguchi, Takahiro Kenmotsu, Koichiro Sadakane and Kenichi Yoshikawa

Polymers 2017, 9(8), 319; https://doi.org/10.3390/polym9080319 - 30 Jul 2017

Cited by 13 | Viewed by 5645

Abstract

Artificial scaffolds such as synthetic gels or chemically-modified glass surfaces that have often been used to achieve cell adhesion are xenobiotic and may harm cells. To enhance the value of cell studies in the fields of regenerative medicine and tissue engineering, it is [...] Read more.

Artificial scaffolds such as synthetic gels or chemically-modified glass surfaces that have often been used to achieve cell adhesion are xenobiotic and may harm cells. To enhance the value of cell studies in the fields of regenerative medicine and tissue engineering, it is becoming increasingly important to create a cell-friendly technique to promote cell–cell contact. In the present study, we developed a novel method for constructing stable cellular assemblies by using optical tweezers in a solution of a natural hydrophilic polymer, dextran. In this method, a target cell is transferred to another target cell to make cell–cell contact by optical tweezers in a culture medium containing dextran. When originally non-cohesive cells are held in contact with each other for a few minutes under laser trapping, stable cell–cell adhesion is accomplished. This method for creating cellular assemblies in the presence of a natural hydrophilic polymer may serve as a novel next-generation 3D single-cell assembly system with future applications in the growing field of regenerative medicine. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessFeature PaperArticle

In Vitro Evaluation of Essential Mechanical Properties and Cell Behaviors of a Novel Polylactic-co-Glycolic Acid (PLGA)-Based Tubular Scaffold for Small-Diameter Vascular Tissue Engineering

by Nuoxin Wang, Wenfu Zheng, Shiyu Cheng, Wei Zhang, Shaoqin Liu and Xingyu Jiang

Polymers 2017, 9(8), 318; https://doi.org/10.3390/polym9080318 - 30 Jul 2017

Cited by 25 | Viewed by 7773

Abstract

In this paper, we investigate essential mechanical properties and cell behaviors of the scaffolds fabricated by rolling polylactic-co-glycolic acid (PLGA) electrospinning (ES) films for small-diameter vascular grafts (inner diameter < 6 mm). The newly developed strategy can be used to fabricate [...] Read more.

In this paper, we investigate essential mechanical properties and cell behaviors of the scaffolds fabricated by rolling polylactic-co-glycolic acid (PLGA) electrospinning (ES) films for small-diameter vascular grafts (inner diameter < 6 mm). The newly developed strategy can be used to fabricate small diameter vascular grafts with or without pre-seeded cells, which are two main branches for small diameter vascular engineering. We demonstrate that the mechanical properties of our rolling-based scaffolds can be tuned flexibly by the number of layers. For cell-free scaffolds, with the increase of layer number, burst pressure and suture retention increase, elastic tensile modulus maintains unchanged statistically, but compliance and liquid leakage decrease. For cell-containing scaffolds, seeding cells will significantly decrease the liquid leakage, but there are no statistical differences for other mechanical properties; moreover, cells live and proliferate well in the scaffold after a 6-day culture. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Biphasic Calcium Phosphate (BCP)-Immobilized Porous Poly (d,l-Lactic-co-Glycolic Acid) Microspheres Enhance Osteogenic Activities of Osteoblasts

by Kyu-Sik Shim, Sung Eun Kim, Young-Pil Yun, Somang Choi, Hak-Jun Kim, Kyeongsoon Park and Hae-Ryong Song

Polymers 2017, 9(7), 297; https://doi.org/10.3390/polym9070297 - 21 Jul 2017

Cited by 7 | Viewed by 7426

Abstract

The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces [...] Read more.

The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces were modified with l-lysine (aminated-PMSs), whereas the BCP NPs were modified with heparin–dopamine (Hep-DOPA) to obtain heparinized–BCP (Hep-BCP) NPs. BCP-IM-PMSs were fabricated via electrostatic interactions between the Hep-BCP NPs and aminated-PMSs. The fabricated BCP-IM-PMSs showed an interconnected pore structure. In vitro studies showed that MG-63 cells cultured on BCP-IM-PMSs had increased alkaline phosphatase activity, calcium content, and mRNA expression of osteocalcin (OCN) and osteopontin (OPN) compared with cells cultured on PMSs. These data suggest that BCP NP-immobilized PMSs have the potential to enhance osteogenic activity. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Preparation of Pendant Group-Functionalized Diblock Copolymers with Adjustable Thermogelling Behavior

by Bo Keun Lee, Ji Hoon Park, Seung Hun Park, Jae Ho Kim, Se Heang Oh, Sang Jin Lee, Bun Yeoul Lee and Moon Suk Kim

Polymers 2017, 9(6), 239; https://doi.org/10.3390/polym9060239 - 20 Jun 2017

Cited by 6 | Viewed by 7264

Abstract

Recently, several thermogelling materials have been developed for biomedical applications. In this study, we prepared methoxy polyethylene glycol (MPEG)-b-(poly(ε-caprolactone)-ran-poly(2-chloride-ε-caprolactone) (PCL-ran-PfCL)) (MP-Cl) diblock copolymers at room temperature via the ring-opening polymerization of caprolactone (CL) [...] Read more.

Recently, several thermogelling materials have been developed for biomedical applications. In this study, we prepared methoxy polyethylene glycol (MPEG)-b-(poly(ε-caprolactone)-ran-poly(2-chloride-ε-caprolactone) (PCL-ran-PfCL)) (MP-Cl) diblock copolymers at room temperature via the ring-opening polymerization of caprolactone (CL) and 2-chloride-ε-caprolactone (fCL) monomers, using the terminal alcohol of MPEG as the initiator in the presence of HCl. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-azide-ε-caprolactone) (PCL-ran-PCL-N₃)) (MP-N₃) was prepared by the reaction of MP-Cl with sodium azide. MPEG-b-(poly(ε-caprolactone)-ran-poly(2-amine-ε-caprolactone) (PCL-ran-PCL-NH₂)) (MP-NH₂) was subsequently prepared by Staudinger reaction. MP-Cl and MP-N₃ showed negative zeta potentials, but MP-NH₂ had a positive zeta potential. MP-Cl, MP-N₃, and MP-NH₂ solutions formed opaque emulsions at room temperature. The solutions exhibited a solution-to-hydrogel phase transition as a function of the temperature and were affected by variation of the chloride, azide, and the amine pendant group, as well as the amount of pendant groups present in their structure. Additionally, the phase transition of MP-Cl, MP-N₃, and MP-NH₂ copolymers was altered by pendant groups. The solution-to-hydrogel phase transition was adjusted by tailoring the crystallinity and hydrophobicity of the copolymers in aqueous solutions. Collectively, MP-Cl, MP-N₃, and MP-NH₂ with various pendant-group contents in the PCL segment showed a solution-to-hydrogel phase transition that depended on both the type of pendant groups and their content. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

In Vitro Biocompatibility, Radiopacity, and Physical Property Tests of Nano-Fe₃O₄ Incorporated Poly-l-lactide Bone Screws

by Hsin-Ta Wang, Pao-Chang Chiang, Jy-Jiunn Tzeng, Ting-Lin Wu, Yu-Hwa Pan, Wei-Jen Chang and Haw-Ming Huang

Polymers 2017, 9(6), 191; https://doi.org/10.3390/polym9060191 - 26 May 2017

Cited by 17 | Viewed by 8573

Abstract

The aim of this study was to fabricate biodegradable poly-l-lactic acid (PLLA) bone screws containing iron oxide (Fe₃O₄) nanoparticles, which are radiopaque and 3D-printable. The PLLA composites were fabricated by loading 20%, 30%, and 40% Fe₃O₄ [...] Read more.

The aim of this study was to fabricate biodegradable poly-l-lactic acid (PLLA) bone screws containing iron oxide (Fe₃O₄) nanoparticles, which are radiopaque and 3D-printable. The PLLA composites were fabricated by loading 20%, 30%, and 40% Fe₃O₄ nanoparticles into the PLLA. The physical properties, including elastic modulus, thermal properties, and biocompatibility of the composites were tested. The 20% nano-Fe₃O₄/PLLA composite was used as the material for fabricating the 3D-printed bone screws. The mechanical performance of the nano-Fe₃O₄/PLLA bone screws was evaluated by anti-bending and anti-torque strength tests. The tissue response and radiopacity of the nano-Fe₃O₄/PLLA bone screws were assessed by histologic and CT imaging studies using an animal model. The addition of nano-Fe₃O₄ increased the crystallization of the PLLA composites. Furthermore, the 20% nano-Fe₃O₄/PLLA composite exhibited the highest thermal stability compared to the other Fe₃O₄ proportions. The 3D-printed bone screws using the 20% nano-Fe₃O₄/PLLA composite provided excellent local tissue response. In addition, the radiopacity of the 20% nano-Fe₃O₄/PLLA screw was significantly better compared with the neat PLLA screw. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Calcium Silicate Improved Bioactivity and Mechanical Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Scaffolds

by Cijun Shuai, Wang Guo, Chengde Gao, Youwen Yang, Yong Xu, Long Liu, Tian Qin, Hang Sun, Sheng Yang, Pei Feng and Ping Wu

Polymers 2017, 9(5), 175; https://doi.org/10.3390/polym9050175 - 14 May 2017

Cited by 34 | Viewed by 5856

Abstract

The poor bioactivity and mechanical properties have restricted its biomedical application, although poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) had good biocompatibility and biodegradability. In this study, calcium silicate (CS) was incorporated into PHBV for improving its bioactivity and mechanical properties, and the porous PHBV/CS composite scaffolds were [...] Read more.

The poor bioactivity and mechanical properties have restricted its biomedical application, although poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) had good biocompatibility and biodegradability. In this study, calcium silicate (CS) was incorporated into PHBV for improving its bioactivity and mechanical properties, and the porous PHBV/CS composite scaffolds were fabricated via selective laser sintering (SLS). Simulated body fluid (SBF) immersion tests indicated the composite scaffolds had good apatite-forming ability, which could be mainly attributed to the electrostatic attraction of negatively charged silanol groups derived from CS degradation to positively charged calcium ions in SBF. Moreover, the compressive properties of the composite scaffolds increased at first, and then decreased with increasing the CS content, which was ascribed to the fact that CS of a proper content could homogeneously disperse in PHBV matrix, while excessive CS would form continuous phase. The compressive strength and modulus of composite scaffolds with optimal CS content of 10 wt % were 3.55 MPa and 36.54 MPa, respectively, which were increased by 41.43% and 28.61%, respectively, as compared with PHBV scaffolds. Additionally, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated MG63 cells had a higher proliferation rate on PHBV/CS composite scaffolds than that on PHBV. Alkaline phosphatase (ALP) staining assay demonstrated the incorporation of CS significantly promoted osteogenic differentiation of MG63 cells on the scaffolds. These results suggest that the PHBV/CS composite scaffolds have the potential in serving as a substitute in bone tissue engineering. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Artificial Spores: Immunoprotective Nanocoating of Red Blood Cells with Supramolecular Ferric Ion-Tannic Acid Complex

by Taegyun Park, Ji Yup Kim, Hyeoncheol Cho, Hee Chul Moon, Beom Jin Kim, Ji Hun Park, Daewha Hong, Joonhong Park and Insung S. Choi

Polymers 2017, 9(4), 140; https://doi.org/10.3390/polym9040140 - 13 Apr 2017

Cited by 51 | Viewed by 9644

Abstract

The blood-type-mismatch problem, in addition to shortage of blood donation, in blood transfusion has prompted the researchers to develop universal blood that does not require blood typing. In this work, the “cell-in-shell” (i.e., artificial spore) approach is utilized to shield the immune-provoking epitopes [...] Read more.

The blood-type-mismatch problem, in addition to shortage of blood donation, in blood transfusion has prompted the researchers to develop universal blood that does not require blood typing. In this work, the “cell-in-shell” (i.e., artificial spore) approach is utilized to shield the immune-provoking epitopes on the surface of red blood cells (RBCs). Individual RBCs are successfully coated with supramolecular metal-organic coordination complex of ferric ion (Fe^III) and tannic acid (TA). The use of isotonic saline (0.85% NaCl) is found to be critical in the formation of stable, reasonably thick (20 nm) shells on RBCs without any aggregation and hemolysis. The formed “RBC-in-shell” structures maintain their original shapes, and effectively attenuate the antibody-mediated agglutination. Moreover, the oxygen-carrying capability of RBCs is not deteriorated after shell formation. This work suggests a simple but fast method for generating immune-camouflaged RBCs, which would contribute to the development of universal blood. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Open AccessArticle

Cell Proliferation on Polyethylene Terephthalate Treated in Plasma Created in SO₂/O₂ Mixtures

by Nina Recek, Matic Resnik, Rok Zaplotnik, Miran Mozetic, Helena Motaln, Tamara Lah-Turnsek and Alenka Vesel

Polymers 2017, 9(3), 82; https://doi.org/10.3390/polym9030082 - 25 Feb 2017

Cited by 8 | Viewed by 5846

Abstract

Samples of polymer polyethylene terephthalate were exposed to a weakly ionized gaseous plasma to modify the polymer surface properties for better cell cultivation. The gases used for treatment were sulfur dioxide and oxygen of various partial pressures. Plasma was created by an electrodeless [...] Read more.

Samples of polymer polyethylene terephthalate were exposed to a weakly ionized gaseous plasma to modify the polymer surface properties for better cell cultivation. The gases used for treatment were sulfur dioxide and oxygen of various partial pressures. Plasma was created by an electrodeless radio frequency discharge at a total pressure of 60 Pa. X-ray photoelectron spectroscopy showed weak functionalization of the samples’ surfaces with the sulfur, with a concentration around 2.5 at %, whereas the oxygen concentration remained at the level of untreated samples, except when the gas mixture with oxygen concentration above 90% was used. Atomic force microscopy revealed highly altered morphology of plasma-treated samples; however, at high oxygen partial pressures this morphology vanished. The samples were then incubated with human umbilical vein endothelial cells. Biological tests to determine endothelialization and possible toxicity of the plasma-treated polyethylene terephthalate samples were performed. Cell metabolic activity (MTT) and in vitro toxic effects of unknown compounds (TOX) were assayed to determine the biocompatibility of the treated substrates. The biocompatibility demonstrated a well-pronounced maximum versus gas composition which correlated well with development of the surface morphology. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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9234 KiB

Open AccessArticle

A Biodegradable Microneedle Cuff for Comparison of Drug Effects through Perivascular Delivery to Balloon-Injured Arteries

by Dae-Hyun Kim, Eui Hwa Jang, Kang Ju Lee, Ji Yong Lee, Seung Hyun Park, Il Ho Seo, Kang Woog Lee, Seung Hyun Lee, WonHyoung Ryu and Young-Nam Youn

Polymers 2017, 9(2), 56; https://doi.org/10.3390/polym9020056 - 8 Feb 2017

Cited by 12 | Viewed by 7735

Abstract

Restenosis at a vascular anastomosis site is a major cause of graft failure and is difficult to prevent by conventional treatment. Perivascular drug delivery has advantages as drugs can be diffused to tunica media and subintima while minimizing the direct effect on endothelium. [...] Read more.

Restenosis at a vascular anastomosis site is a major cause of graft failure and is difficult to prevent by conventional treatment. Perivascular drug delivery has advantages as drugs can be diffused to tunica media and subintima while minimizing the direct effect on endothelium. This in vivo study investigated the comparative effectiveness of paclitaxel, sirolimus, and sunitinib using a perivascular biodegradable microneedle cuff. A total of 31 New Zealand white rabbits were used. Rhodamine was used to visualize drug distribution (n = 3). Sirolimus- (n = 7), sunitinib- (n = 7), and paclitaxel-loaded (n = 7) microneedle cuffs were placed at balloon-injured abdominal aortae and compared to drug-free cuffs (n = 7). Basic histological structures were not affected by microneedle devices, and vascular wall thickness of the device-only group was similar to that of normal artery. Quantitative analysis revealed significantly decreased neointima formation in all drug-treated groups (p < 0.001). However, the tunica media layer of the paclitaxel-treated group was significantly thinner than that of other groups and also showed the highest apoptotic ratio (p < 0.001). Proliferating cell nuclear antigen (PCNA)-positive cells were significantly reduced in all drug-treated groups. Sirolimus or sunitinib appeared to be more appropriate for microneedle devices capable of slow drug release because vascular wall thickness was minimally affected. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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32992 KiB

Open AccessArticle

Microsphere-Based Hierarchically Juxtapositioned Biphasic Scaffolds Prepared from Poly(Lactic-co-Glycolic Acid) and Nanohydroxyapatite for Osteochondral Tissue Engineering

by K. T. Shalumon, Chialin Sheu, Yi Teng Fong, Han-Tsung Liao and Jyh-Ping Chen

Polymers 2016, 8(12), 429; https://doi.org/10.3390/polym8120429 - 10 Dec 2016

Cited by 22 | Viewed by 8954

Abstract

This study aims to prepare biphasic osteochondral scaffolds based on seamless joining of sintered polymer and polymer/ceramic microspheres for co-culture of chondrocytes and bone marrow stem cells (BMSCs). Poly(lactide-co-glycolide) (PLGA) microspheres and 10% nanohydroxyapatite (nHAP)-incorporated PLGA (PGA/nHAP) microspheres were prepared through [...] Read more.

This study aims to prepare biphasic osteochondral scaffolds based on seamless joining of sintered polymer and polymer/ceramic microspheres for co-culture of chondrocytes and bone marrow stem cells (BMSCs). Poly(lactide-co-glycolide) (PLGA) microspheres and 10% nanohydroxyapatite (nHAP)-incorporated PLGA (PGA/nHAP) microspheres were prepared through the oil-in-water precipitation method. Virgin (V) and composite (C) scaffolds were prepared from 250–500 µm PLGA and PLGA/nHAP microspheres, respectively, while osteochondral (OC) scaffolds were fabricated through the combination of V and C scaffolds. Physico-chemical properties of scaffolds were characterized through microscopic-spectroscopic evaluations. The effect of nHAP in scaffolds was investigated through thermogravimetric analysis and mechanical testing, while surface hydrophobicity was tested through contact angle measurements. Rabbit chondrocytes and BMSCs were used for cell culture, and cell morphology and proliferation were determined from SEM and DNA assays. Alizarin red and Alcian blue stains were used to identify the in vitro bone and cartilage tissue-specific regeneration, while cetylpyridinium chloride was used to quantitatively estimate calcium in mineralized bone. For co-culture in OC scaffolds, BMSCs were first seeded in the bone part of the scaffold and cultured in osteogenic medium, followed by seeding chondrocytes in the cartilage part, and cultured in chondrocyte medium. High cell viability was confirmed from the Live/Dead assays. Actin cytoskeleton organization obtained by DAPI-phalloidin staining revealed proper organization of chondrocytes and BMSCs in OC scaffolds. Immunofluorescent staining of bone (type I collagen and osteocalcin (OCN)) and cartilage marker proteins (type II collagen (COL II)) confirmed cellular behavior of osteoblasts and chondrocytes in vitro. Using an ectopic osteochondral defect model by subcutaneous implantation of co-cultured OC scaffolds in nude mice confirmed cell proliferation and tissue development from gross view and SEM observation. IF staining of OCN and COL II in the bone and cartilage parts of OC scaffolds and tissue-specific histological analysis exhibited a time-dependent tissue re-modeling and confirmed the potential application of the biphasic scaffold in osteochondral tissue engineering. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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Review

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Open AccessReview

Gelatin-Based Hydrogels for Organ 3D Bioprinting

by Xiaohong Wang, Qiang Ao, Xiaohong Tian, Jun Fan, Hao Tong, Weijian Hou and Shuling Bai

Polymers 2017, 9(9), 401; https://doi.org/10.3390/polym9090401 - 30 Aug 2017

Cited by 235 | Viewed by 23233

Abstract

Three-dimensional (3D) bioprinting is a family of enabling technologies that can be used to manufacture human organs with predefined hierarchical structures, material constituents and physiological functions. The main objective of these technologies is to produce high-throughput and/or customized organ substitutes (or bioartificial organs) [...] Read more.

Three-dimensional (3D) bioprinting is a family of enabling technologies that can be used to manufacture human organs with predefined hierarchical structures, material constituents and physiological functions. The main objective of these technologies is to produce high-throughput and/or customized organ substitutes (or bioartificial organs) with heterogeneous cell types or stem cells along with other biomaterials that are able to repair, replace or restore the defect/failure counterparts. Gelatin-based hydrogels, such as gelatin/fibrinogen, gelatin/hyaluronan and gelatin/alginate/fibrinogen, have unique features in organ 3D bioprinting technologies. This article is an overview of the intrinsic/extrinsic properties of the gelatin-based hydrogels in organ 3D bioprinting areas with advanced technologies, theories and principles. The state of the art of the physical/chemical crosslinking methods of the gelatin-based hydrogels being used to overcome the weak mechanical properties is highlighted. A multicellular model made from adipose-derived stem cell proliferation and differentiation in the predefined 3D constructs is emphasized. Multi-nozzle extrusion-based organ 3D bioprinting technologies have the distinguished potential to eventually manufacture implantable bioartificial organs for purposes such as customized organ restoration, high-throughput drug screening and metabolic syndrome model establishment. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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1581 KiB

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Characterization of Cell Scaffolds by Atomic Force Microscopy

by Jagoba Iturri and José L. Toca-Herrera

Polymers 2017, 9(8), 383; https://doi.org/10.3390/polym9080383 - 21 Aug 2017

Cited by 45 | Viewed by 9635

Abstract

This review reports on the use of the atomic force microscopy (AFM) in the investigation of cell scaffolds in recent years. It is shown how the technique is able to deliver information about the scaffold surface properties (e.g., topography), as well as about [...] Read more.

This review reports on the use of the atomic force microscopy (AFM) in the investigation of cell scaffolds in recent years. It is shown how the technique is able to deliver information about the scaffold surface properties (e.g., topography), as well as about its mechanical behavior (Young’s modulus, viscosity, and adhesion). In addition, this short review also points out the utilization of the atomic force microscope technique beyond its usual employment in order to investigate another type of basic questions related to materials physics, chemistry, and biology. The final section discusses in detail the novel uses that those alternative measuring modes can bring to this field in the future. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

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