Cellular Behavior on Epidermal Growth Factor (EGF)-Immobilized PCL/Gelatin Nanofibrous Scaffolds

Nano-scaled poly(ε-caprolactone) (PCL) and PCL/gelatin fibrous scaffolds with immobilized epidermal growth factor (EGF) were prepared for the purpose of wound-healing treatments. The tissue scaffolds were fabricated by electrospinning and the parameters that affect the electrospinning process were optimized. While the fiber diameters were 488 ± 114 nm and 663 ± 107 nm for PCL and PCL/gelatin scaffolds, respectively, the porosities were calculated as 79% for PCL and 68% for PCL/gelatin scaffolds. Electrospun PCL and PCL/gelatin scaffolds were first modified with 1,6-diaminohexane to introduce amino groups on their surfaces, then EGF was chemically conjugated to the surface of nanofibers. The results obtained from Attenuated Total Reflectance Fourier Transform Infrared (ATR–FT-IR) spectroscopy and quantitative measurements showed that EGF was successfully immobilized on nanofibrous scaffolds. L929 mouse fibroblastic cells were cultivated on both neat and EGF-immobilized PCL and PCL/gelatin scaffolds in order to investigate the effect of EGF on cell spreading and proliferation. According to the results, especially EGF-immobilized PCL/gelatin scaffolds exerted early cell spreading and superior and rapid proliferation compared to EGF-immobilized PCL scaffolds and neat PCL, PCL/gelatin scaffolds. Consequently, EGF-immobilized PCL/gelatin scaffolds could potentially be employed as novel scaffolds for skin tissueengineering applications.     

Biocompatible nanofiber matrices for the engineering of a dermal substitute for skin regeneration

Natural and synthetic biodegradable nanofibers are extensively used for biomedical applications and tissue engineering. Biocompatibility and a well-established safety profile for polycaprolactone (PCL) and collagen represent a favorable matrix for preparing a dermal substitute for engineering skin. Collagen synthesized by fibroblasts is a good surface active agent and demonstrates its ability to penetrate a lipid-free interface. During granulation tissue formation, fibronectin provides a temporary substratum for migration and proliferation of cells and provides a template for collagen deposition, which increases stiffness and tensile strength of this healing tissues. The objective of this study was to fabricate nanofiber matrices from novel biodegradable PCL and collagen to mimic natural extracellular matrix (ECM) and to examine the cell behavior, cell attachment, and interaction between cells and nanofiber matrices. Collagen nanofiber matrices show a significant (p < 0.001) level of fibroblast proliferation and increase up to 54% compared with control tissue culture plate (TCP) after 72 h. The present investigation shows that PCL-coated collagen matrices are suitable for fibroblast growth, proliferation, and migration inside the matrices. This novel biodegradable PCL and collagen nanofiber matrices support the attachment and proliferation of human dermal fibroblasts and might have potential in tissue engineering as a dermal substitute for skin regeneration.     

Regulation of migratory activity of human keratinocytes by topography of multiscale collagen-containing nanofibrous matrices

Nanofibrous matrices hold great promise in skin wound repair partially due to their capability of recapturing the essential attributes of native extracellular matrix (ECM). With regard to limited studies on the effect of nanofibrous matrices on keratinocytes, the present study was aimed to understand how the topographical feature of nanofibrous matrices regulates keratinocyte motility by culturing keratinocytes on polycaprolactone (PCL)/collagen nanofibrous matrices (rough surface with fiber diameters of 331 ± 112 nm) or the matrices coated with a thin layer of collagen gel to form a secondary ultrafine fibrous network (smooth surface with ultrafine fiber diameters of 55 ± 26 nm). It was found that the PCL/collagen nanofibrous matrices alone did not stimulate cell migration, while collagen gel coating could significantly increase cell motility. Further studies demonstrated that the ultrafine fibrous network of collagen gel coating significantly activated integrin β1, Rac1 and Cdc42, facilitated the deposition of laminin-332 (formerly called laminin-5), and promoted the expression of active matrix metalloproteinases (MMPs) (i.e., MMP-2 and 9). Neutralization of integrin β1 activity abrogated the gel coating-induced keratinocyte migration. These findings provide important evidence on the role of topographical features of nanofibrous matrices in regulating the phenotypic alteration of keratinocytes and suggest the possible utility of collagen-containing nanofibrous matrices for skin regeneration especially in re-epithelialization.     

Biomimetic LBL structured nanofibrous matrices assembled by chitosan/collagen for promoting wound healing

This paper reports the fabrication of biomimetic nanofibrous matrices via co-electrospinning of polycaprolactone (PCL)/cellulose acetate (CA) and layer-by-layer self-assembly (LBL) of positively charged chitosan (CS) and negatively charged Type Ⅰ collagen on the nanofibrous matrix. FE-SEM images indicate that the average fiber diameter increased from 392 to 541 nm when the coating bilayers varied from 5 to 20.5. Besides, the excellent biocompatibility and enhanced attachment and spreading of normal human dermal fibroblasts (NHDFs) of prepared nanofibrous mats are confirmed by MTT and SEM results. Furthermore, the LBL structured (CS/collagen)_n nanofibrous mats greatly improve the cell migration in vitro, promote re-epithelialization and vascularization in vivo, and up-regulate the expression of collagen Ⅳ and α-tubulin, as well as the Integrin β1 and phosphorylation of focal adhesion kinase (FAK) at Tyr-397. The levels of expressed protein are significantly enhanced with increasing coating bilayers via immunohistochemistry and western blotting analyses. Collectively, these results suggest that the LBL structured biomimetic nanofibrous matrices may enhance cell migration and further promote the skin regeneration by up-regulating the secretion of ECM protein and triggering Integrin/FAK signaling pathway, which demonstrate the potential use of the nanofibrous mats to rapidly restore the structural and functional properties of wounded skin.     

Stem cell differentiation to epidermal lineages on electrospun nanofibrous substrates for skin tissue engineering

Bone marrow (BM) mesenchymal stem cells (MSC) capable of differentiating along the epidermal lineage on engineered nanofibrous scaffolds have great potential for bionanomaterial-cell transplantation therapy of skin wounds. MSC have been the focus of many tissue engineering studies, mainly because of their multipotential properties. We investigated the potential of human BM-derived MSC for epidermal cell differentiation in vitro on electrospun collagen/poly(l-lactic acid)-co-poly(3-caprolactone) (Coll/PLLCL) nanofibrous scaffolds. PLLCL and Coll/PLLCL nanofibrous scaffolds were fabricated by an electrospinning process and their chemical and mechanical characterization carried out by scanning electron microscopy (SEM), water contact angle determination, Fourier transform infrared spectroscopy, and tensile testing. The differentiation of MSC was carried out using epidermis inducing factors, including epidermal growth factor (EGF) and 1,25-dihydroxyvitamin D(3), in culture medium. The proliferation of MSC evaluated by cell proliferation assay showed that the number of cells grown on Coll/PLLCL nanofibrous scaffolds was significantly higher than those on PLLCL scaffolds. The SEM results showed that MSC differentiated on Coll/PLLCL nanofibrous scaffolds showed a round keratinocyte morphology and expressed keratin 10, filaggrin and partial involucrin protein by immunofluorescent microscopic studies. The interaction of MSC and nanofibers was studied and we concluded that the electrospun Coll/PLLCL nanofibers could mimic the native skin extracellular matrix environment and are promising substrates for advanced skin tissue engineering. Our studies on the differentiation of MSC along the epidermal lineage on nanofibrous scaffolds suggest their potential application in skin regeneration without regional differentiation.     

Preparation of collagen-coated electrospun nanofibers by remote plasma treatment and their biological properties

Non-woven poly(epsilon-caprolactone) (PCL) nanofibers were prepared by electrospinning and type-I collagen was then immobilized on the nanofibers after surface modification by remote plasma treatment. A collagen-coated surface was observed and characterized using scanning electron microscopy (SEM), contact-angle measurement and X-ray photoelectron spectroscopy (XPS). The results confirmed the successful immobilization of collagen on the nanofibers and the great improvement of surface wettability due to coating. The amounts of immobilized collagen were also measured by colorimetry. The results showed that remote plasma treatment can provide higher immobilization of collagen than conventional plasma. Primary human dermal fibroblasts (HDFs) were cultured to evaluate the biocompatibility of collagen-immobilized electrospun PCL nanofibers. The results of MTT testing and SEM showed that collagen immobilization can obviously enhance the attachment spreading and proliferation of HDFs compared with the pristine material. The collagen-immobilized non-woven PCL nanofibers can be expected to be a potential scaffold material for tissue engineering.     

胶原/壳聚糖复合纳米纤维膜引导骨再生的细胞学研究

采用静电纺丝技术制备胶原/壳聚糖复合纳米纤维膜,研究其作为引导骨再生生物膜的细胞生物相容性及诱导成骨性。以乙酸为溶剂,聚环氧乙烯(PEO)为增塑剂,采用静电纺丝技术制备胶原纳米纤维膜及不同比例的胶原/壳聚糖复合纳米纤维膜(胶原、壳聚糖、PEO质量比5∶1∶4,5∶2∶3,5∶4∶1),电子显微镜观察4种纳米纤维膜的表面形态;将骨髓间充质干细胞种植于胶原纳米纤维膜及表面形态较好的胶原/壳聚糖纳米纤维膜上,通过MTT法、碱性磷酸酶检测、细胞内胶原检测、免疫荧光染色及茜素红染色法观察,研究其细胞生物相容性及诱导成骨性。扫描电子显微镜观察胶原纳米纤维膜及质量比为5∶1∶4的胶原/壳聚糖复合纳米纤维膜的纤维光滑,直径均一。MTT法检测显示,胶原纳米纤维膜和胶原/壳聚糖复合纳米纤维膜均可促进骨髓间充质干细胞的粘附和增殖。细胞培养14 d后,胶原/壳聚糖复合纳米纤维膜上细胞内胶原含量检测为2.02 mg/gport,高于胶原纳米纤维膜组的1.63 mg/gport胶原含量(P<0.05),且胶原/壳聚糖复合纳米纤维膜上细胞内碱性磷酸酶、骨钙素及钙化结节的形成均高于胶原纳米纤维膜组。胶原/壳聚糖复合纳米纤维膜可促进骨髓间充质干细胞的增殖和分化,有望应用于骨再生的研究。     

Electrosprayed Hydroxyapatite on Polymer Nanofibers to Differentiate Mesenchymal Stem Cells to Osteogenesis

Abstract

Electrospraying of hydroxyapatite (HA) nanoparticles onto the surface of polymer nanofibers provides a potentially novel substrate for the adhesion, proliferation and differentiation of mesenchymal stem cells (MSCs) into bone tissue regeneration. HA nanoparticles (4%) were electrosprayed on the surface of electrospun polycaprolactone (PCL) nanofibers (420 ± 15 nm) for bone tissue engineering. PCL/HA nanofibers were comparatively characterized with PCL/Collagen (275 ± 56 nm) nanofibers by FT-IR analysis to confirm the presence of HA. Fabricated PCL/HA and PCL/Collagen nanofibers and TCP (control) were used for the differentiation of equine MSC into osteogenic lineages in the presence of DMEM/F12 medium supplemented with β-glycerophosphate, ascorbic acid and dexamethasone. Cell proliferation and differentiation into an osteogenic lineage was evaluated by MTS assay, SEM observation, ALP activity, ARS staining, quantification of mineral deposition and expression of osteocalcin. Proliferation of MSCs increased significantly (P ? 0.05) up to 12% in PCL/Collagen (day 15) compared to PCL/HA nanofibrous substrate. ALP activity was increased 20% in PCL/HA by day 10 confirming the direction of osteogenic lineage from MSCs differentiation. PCL/HA stimulated an increased mineral secretion up to 26% by day 15 on ARS staining compared to PCL/Collagen nanofibers and showing cuboidal morphology by expressing osteocalcin. These results confirmed that the specifically fabricated PCL/HA composite nanofibrous substrate enhanced the differentiation of MSCs into osteogenesis.     

Electrospun biocomposite nanofibrous scaffolds for neural tissue engineering

Bridging of nerve gaps after injury is a major problem in peripheral nerve regeneration. Considering the potential application of a bio-artificial nerve guide material, polycaprolactone (PCL)/chitosan nanofibrous scaffolds was designed and evaluated in vitro using rat Schwann cells (RT4-D6P2T) for nerve tissue engineering. PCL, chitosan, and PCL/chitosan nanofibers with average fiber diameters of 630, 450, and 190 nm, respectively, were fabricated using an electrospinning process. The surface chemistry of the fabricated nanofibers was determined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Simple blending of PCL with chitosan proved an easy and efficient method for fabricating PCL/chitosan nanofibrous scaffolds, whose surface characteristics proved more hydrophilic than PCL nanofibers. Evaluation of mechanical properties showed that the Young's modulus and strain at break of the electrospun PCL/chitosan nanofibers were better than those of the chitosan nanofibers. Results of cell proliferation studies on nanofibrous scaffolds using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay showed 48% more cell proliferation on PCL/chitosan scaffolds than on PCL scaffolds after 8 days of culture. PCL/chitosan scaffolds showed better cell proliferation than PCL scaffolds and maintained their characteristic cell morphology, with spreading bipolar elongations to the nanofibrous substrates. This electrospun nanofibrous matrix thus proved of specific interest in tissue engineering for peripheral nerve regeneration.     

Apatite-mineralized polycaprolactone nanofibrous web as a bone tissue regeneration substrate

Degradable synthetic polymers with a nanofibrous structure have shown great promise in populating and recruiting cells for the reconstruction of damaged tissues. However, poor cell affinity and lack of bioactivity have limited their potential usefulness in bone regeneration. We produced polymeric nanofiber poly(epsilon-caprolactone) (PCL) with its surface mineralized with bone-like apatite for use as bone regenerative and tissue engineering matrices. PCL was first electrospun into a nanofibrous web, and the surface was further mineralized with apatite following a series of solution treatments. The surface of the mineralized PCL nanofiber was observed to be almost fully covered with nanocrystalline apatites. Through mineralization, the wettability of the nanofiber matrix was greatly improved. Moreover, the murine-derived osteoblastic cells were shown to attach and grow actively on the apatite-mineralized nanofibrous substrate. In particular, the mineralized PCL nanofibrous substrate significantly stimulated the expression of bone-associated genes, including Runx2, collagen type I, alkaline phosphatase, and osteocalcin, when compared with the pure PCL nanofiber substrate without mineralization. The currently developed polymer nanofibrous web with the bioactive mineralized surface is considered to be potentially useful as bone regenerative and tissue engineering matrices.     

Novel Biodegradable Polycaprolactone Occlusion Device Combining Nanofibrous PLGA/Collagen Membrane for Closure of Atrial Septal Defect (ASD)

The purpose of this report was to develop novel biodegradable occlusion devices for closure of atrial septal defects (ASD). To manufacture the biodegradable occluders, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molding machine. They were then assembled and hot-spot welded into double umbrella-like devices of 50 mm in diameter. A special mechanism at the axis of the occluder was designed to self-lock the occluder after the two umbrellas were expanded. Furthermore, a nanofibrous matrix of poly-d-l-lactide-glycolide (PLGA)/type I collagen blend was produced via electrospinning to develop biodegradable and biomimetic anti-shunt membranes for the occluders. Characterization of the biodegradable PCL occluders was carried out. PCL occluders exhibited mechanical properties comparable to that of commercially available Amplatzer occluders. The sealing capability of biodegradable occluders was found superior to that of Amplatzer occluders. In addition, the cell attachment and spreading of endothelial cells seeded on the PLGA/collagen nanofibrous matrix and the interaction between cells and PLGA/collagen nanofibers were studied. The nanofibrous membranes made of PLGA/collagen were very effective in promoting cell proliferation during culture.     

Electrospinning of collagen nanofibers: effects on the behavior of normal human keratinocytes and early-stage wound healing

Electrospinning of type I collagen in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to fabricate a biomimetic nanofibrous extracellular matrix for tissue engineering was investigated. The average diameter of collagen nanofibers electrospun from 8% collagen solution in HFIP was 460 nm (range of 100-1200 nm). The as-spun collagen nanofibrous matrix was chemically cross-linked by glutaraldehyde vapor with a saturated aqueous solution and then treated with aqueous 0.1m glycine to block unreacted aldehyde groups. With vapor phase cross-linking for 12h, porosity of the collagen matrix decreased from 89% to 71%. The collagen nanofibrous matrix showed good tensile strength, even in aqueous solution. Effects on cytocompatibility, cell behavior, cell and collagen nanofiber interactions, and open wound healing in rats were examined. Relatively low cell adhesion was observed on uncoated collagen nanofibers, whereas collagen nanofibrous matrices treated with type I collagen or laminin were functionally active in responses in normal human keratinocytes. Collagen nanofibrous matrices were very effective as wound-healing accelerators in early-stage wound healing. Our results indicate that cross-linked collagen nanofibers coated with ECM proteins, particularly type I collagen, may be a good candidate for biomedical applications, such as wound dressing and scaffolds for tissue engineering.     

A dermal equivalent developed from adipose-derived stem cells and electrospun polycaprolactone matrix: an in vitro and in vivo study

Polycaprolactone (PCL) is used as a material of choice for surgical sutures, wound dressings, contraceptives, fixation devices and dentistry in paramedical sciences. In addition, adipose-derived stem cells (ASCs) have been shown to be effective in the treatment of acute and chronic wounds. This study aimed to evaluate the effect of electrospun PCL fibers on keratinocyte differentiation of ASCs and wound healing. PCL solution was electrospun and characterized. Isolated and characterized ASCs were differentiated into keratinocyte-like cells on a tissue culture plate (TCP) and PCL matrices and compared. PCL nano-/microfibers cultured with ASCs (test group) or alone (control) were implanted as a dermal substitute for wound healing. There were significant increases in the proliferation rate and expression level of cytokeratin 14, filaggrin and involucrin in cells cultured on PCL matrices compared to TCP (p < 0.05). After histological and immunological evaluation of the reconstituted skin, a thick epidermal layer with several skin appendages was evidently observed in the ASC/PCL group, whereas no real and mature epidermis was formed, especially in the central area of the healing wound in the pure PCL group on day 14. Pure PCL, if possessing suitable properties including good adhesiveness, high proliferative capability, inductive elasticity and stiffness for migration and differentiation, could drive the keratinocyte differentiation of ASCs and act as an efficient dermal equivalent to promote wound healing.     

Nanofiber enabled layer-by-layer approach toward three-dimensional tissue formation

Taking rapid and efficient formation of functional tissues as our long-term goal, we discuss in this study a new and generic approach toward formation of multilayered three-dimensional (3D) tissues using nanofibers. 3:1 poly (epsilon-caprolactone) (PCL) (8% w/v)/collagen (8.0% w/v) solution was electrospun into nanofibers with an average diameter of 454.5 +/- 84.9 nm. The culture of human dermal fibroblasts (NHDF) on PCL/collagen nanofibers showed a high initial cell adhesion (88.1 +/- 1.5%), and rapid cell spreading with spindle morphology. Three-dimensional multilayered cell-nanofiber constructs were built with alternating NHDF seeding (1 x 10(5)cells/layer) and PCL/collagen nanofiber collection on site of electrospinning, where almost all the seeded cells retained in the constructs. The formed construct showed layered structure with uniform cell distribution in between layers of PCL/collagen nanofibers. In the 3D constructs, cells continuously proliferated and deposited new extracellular matrix. By culturing either fibroblast/fiber layered constructs or keratinocyte/fibroblast/fiber layered constructs, dermal-like tissues or bilayer skin tissues (containing both epidermal and dermal layers) were consequently produced within 1 week. Taken together, the present study reports a novel approach to 3D multilayered tissue formation using a bottom-up, on-site layer-by-layer cell assembly while electrospinning. This approach has marked potentials to form functional tissues composed of multiple types of cells, heterogeneous scaffold composition, and customized specific microenvironment for cells.     

Evaluation of ultra-thin poly(epsilon-caprolactone) films for tissue-engineered skin

Various natural and synthetic polymeric materials have been used as scaffold matrices for tissue-engineered skin. However, the commercially available skin replacement products pose problems of poor mechanical properties and immunological rejection. We have thus developed a film of 5 microm thickness, via biaxial stretching of poly(epsilon-caprolactone) (PCL), as a potential matrix for living skin replacements. The aim of this study was to evaluate the feasibility of using biaxially stretched PCL films as matrices for culturing human dermal fibroblasts. For this purpose, we cultured human dermal fibroblasts for 7 days on the films. Glass cover slips and polyurethane (PU) sheets were used as controls. The data from phase contrast light, confocal laser, and scanning electron microscopy suggested that biaxially stretched PCL films support the attachment and proliferation of human dermal fibroblasts. Thymidine-labeling results showed quantitatively that cell proliferation on the PCL films was superior to that on the PU samples. These results indicated that biaxially stretched PCL films supported the growth of human dermal fibroblasts and might have potential to be applied in tissue engineering a dermal equivalent or skin graft.     

Electrospun-modified nanofibrous scaffolds for the mineralization of osteoblast cells

Biocompatible polycaprolactone (PCL) and hydroxyapatite (HA) were fabricated into nanofibrous scaffolds for the mineralization of osteoblasts in bone tissue engineering. PCL and PCL/HA nanofibrous surface were modified using oxygen plasma treatment and showing 0 degrees contact angle for the adhesion and mineralization of osteoblast cells. The fiber diameter, pore size and porosity of nanofibrous scaffolds were estimated to be 220-625 nm, 3-20 microm, and 87-92% respectively. The ultimate tensile strength of PCL was about 3.37 MPa and PCL/HA was 1.07 MPa to withstand the long term culture of osteoblasts on nanofibrous scaffolds. Human fetal osteoblast cells (hFOB) were cultured on PCL and PCL/HA surface modified and unmodified nanofibrous scaffolds. The osteoblast proliferation rate was significantly (p < 0.001) increased in surface-modified nanofibrous scaffolds. FESEM showed normal phenotypic cell morphology and mineralization occurred in PCL/HA nanofibrous scaffolds, HA acting as a chelating agent for the mineralization of osteoblast to form bone like apatite for bone tissue engineering. EDX and Alizarin Red-S staining indicated mineral Ca(2+) and phosphorous deposited on the surface of osteoblast cells. The mineralization was significantly increased in PCL/HA-modified nanofibrous scaffolds and appeared as a mineral nodule synthesized by osteoblasts similar to apatite of the natural bone. The present study indicated that the PCL/HA surface-modified nanofibrous scaffolds are potential for the mineralization of osteoblast for bone tissue engineering.     

Electrospun bio-composite P(LLA-CL)/collagen I/collagen III scaffolds for nerve tissue engineering

One of the biggest challenges in peripheral nerve tissue engineering is to create an artificial nerve graft that could mimic the extracellular matrix (ECM) and assist in nerve regeneration. Bio-composite nanofibrous scaffolds made from synthetic and natural polymeric blends provide suitable substrate for tissue engineering and it can be used as nerve guides eliminating the need of autologous nerve grafts. Nanotopography or orientation of the fibers within the scaffolds greatly influences the nerve cell morphology and outgrowth, and the alignment of the fibers ensures better contact guidance of the cells. In this study, poly (L-lactic acid)-co-poly(ε-caprolactone) or P(LLA-CL), collagen I and collagen III are utilized for the fabrication of nanofibers of different compositions and orientations (random and aligned) by electrospinning. The morphology, mechanical, physical, and chemical properties of the electrospun scaffolds along with their biocompatibility using C17.2 nerve stem cells are studied to identify the suitable material compositions and topography of the electrospun scaffolds required for peripheral nerve regeneration. Aligned P(LLA-CL)/collagen I/collagen III nanofibrous scaffolds with average diameter of 253 ± 102 nm were fabricated and characterized with a tensile strength of 11.59 ± 1.68 MPa. Cell proliferation studies showed 22% increase in cell proliferation on aligned P(LLA-CL)/collagen I/collagen III scaffolds compared with aligned pure P(LLA-CL) scaffolds. Results of our in vitro cell proliferation, cell-scaffold interaction, and neurofilament protein expression studies demonstrated that the electrospun aligned P(LLA-CL)/collagen I/collagen III nanofibrous scaffolds mimic more closely towards the ECM of nerve and have great potential as a substrate for accelerated regeneration of the nerve.     

Novel biodegradable electrospun membrane: scaffold for tissue engineering

Nonwoven fibrous matrixes have been widely used as scaffolds in tissue engineering, and modification of microstructure of these matrices is needed to organize cells in three-dimensional space with spatially balanced proliferation and differentiation required for functional tissue development. The objective of this study was fabrication of nanofibrous matrix from novel biodegradable poly(p-dioxanone-co-L-lactide)-block-poly(ethylene glycol) (PPDO/PLLA-b-PEG) copolymer, and to examine cell proliferation, morphology of cell-matrix interaction with the electrospun nanofibrous matrix. The electrospun structure composed of PPDO/PLLA-b-PEG fibers with an average diameters of 380 nm, median pore size 8 microm, porosity more than 80% and mechanical strength 1.4 MPa, is favorable for cell-matrix interaction and supports the active biocompatibility of the structure. NIH 3T3 fibroblast cell seeded on the structure tend to maintain phenotypic shape and guided growth according to nanofiber orientation. Good capability of the nanofibrous structure for supporting the cell attachment and proliferation are observed. This novel biodegradable scaffold will be applicable for tissue engineering based upon its unique architecture, which acts to support and guide cell growth.     

Polypyrrole-contained electrospun conductive nanofibrous membranes for cardiac tissue engineering

Cardiac tissue engineering (TE) is one of the most promising strategies to reconstruct infarct myocardium and the major challenge is to generate a bioactive substrate with suitable chemical, biological, and conductive properties, thus mimicking the extracellular matrix (ECM) both structurally and functionally. In this study, polypyrrole/poly(ε-caprolactone)/gelatin nanofibrous scaffolds were electrospun by incorporating different concentrations of polypyrrole (PPy) to PCL/gelatin (PG) solution. Morphological, chemical, mechanical, and biodegradation properties of the electrospun nanofibers were evaluated. Our data indicated that by increasing the concentration of PPy (0-30%) in the composite, the average fiber diameters reduced from 239 ± 37 nm to 191 ± 45 nm, and the tensile modulus increased from 7.9 ± 1.6 MPa to 50.3 ± 3.3 MPa. Conductive nanofibers containing 15% PPy (PPG15) exhibited the most balanced properties of conductivity, mechanical properties, and biodegradability, matching the requirements for regeneration of cardiac tissue. The cell proliferation assay, SEM, and immunostaining analysis showed that the PPG15 scaffold promote cell attachment, proliferation, interaction, and expression of cardiac-specific proteins better than PPG30. Electrospun PPG15 conductive nanofibrous scaffold could be desirable and promising substrates suitable for the regeneration of infarct myocardium and cardiac defects.