Electrospun Polycaprolactone Scaffolds Research Articles

A simple route to functionalising electrospun polymer scaffolds with surface biomolecules

Surface functionalisation of polymeric electrospun scaffolds with therapeutic biomolecules is often explored in regenerative medicine and tissue engineering. However, the bioconjugation method must be carefully selected to prevent partial or full loss of activity of the biomolecule following chemical manipulation. Perfluorophenyl azide bearing a N‐hydroxysuccinimide (PFPA-NHS) active ester group is a versatile tool for UV-initiated covalent coupling of amine-containing molecules to hydrocarbon-based polymers, such as polydioxanone or polycaprolactone (PCL). This study therefore explored the feasibility of PFPA-NHS functionalisation of electrospun PCL scaffolds with model biomolecules. Protein conjugation was extensively explored using fluorescence staining and attachment studies, confirming the retention of amine coupling capability following photografting of PFPA-NHS to the PCL surface. The effect of the washing method used to remove unreacted PFPA was explored in Caco-2 cell viability studies, and it was determined that sonication washing is required to avoid cell death. A model enzyme, catalase, was then successfully attached to the surface of PCL scaffolds for potential applications in oncological photodynamic therapy. Catalase retained its enzymatic activity following attachment to the fibres and the majority of the enzyme (~60%) remained bound to the fibre after incubation in an aqueous environment for six days. The anticipated prolonged presentation and sustained release of proteins as a result of PFPA-NHS conjugation could be advantageous in progressing protein-based therapies.

Electrospun Polycaprolactone Scaffolds Using an Ionic Liquid as Alternative Solvent: Morphometric, Mechanical and Biological Properties

AbstractIonic liquids (IL) are a greener alternative to aggressive organic solvents used for biopolymers dissolution in the electrospinning process. Nevertheless, the effect of IL on the properties of the electrospun materials is still a gap. In this work, we obtain polycaprolactone (PCL) electrospun mats using two solvents, either trichloromethane (CHCl3) – a conventional toxic and carcinogenic solvent – or 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl), an ionic liquid. The differences between the respective electrospun products were assessed through the scaffold's morphology, mechanical properties and cytotoxicity. The use of IL resulted in the formation of textured thinner fibers, enhancing the surface area in 43 %. IL induced a lower rupture stress and elongation of the mats of 34 and 39 %, respectively, while the elastic modulus and yield stress did not present significant differences. The cytotoxicity assays using L929 cells detected a number of viable cells slightly higher for the scaffold produced with IL. Cell interaction tests also revealed that L929 cells adhere and proliferate on both scaffolds. However, the cell adhesion was higher for the mats fabricated using IL. Beyond the results, this work sheds light on the pros and cons of tissue engineering scaffolds produced with the aid of less hazardous solvents.

Modulating electrospun polycaprolactone scaffold morphology and composition to alter endothelial cell proliferation and angiogenic gene response.

The aim of this study was to look at how the composition and morphology of polymer scaffolds could be altered to create an optimized environment for endothelial cells. Four polycaprolactone (PCL) scaffolds were electrospun with increasing fibre diameters ranging from 1.64 μm to 4.83 μm. The scaffolds were seeded with human umbilical vein endothelial cells (HUVEC) and cultured for 12 days. PCL scaffolds were then electrospun incorporating decellularized bovine aorta ECM and cultured in a hypoxic environment. We noted deeper cell infiltration on the largest fibre diameter compared to the other three scaffolds which resulted in an increase in the gene expression of CD31; a key angiogenic marker. Increased cell viability and cell proliferation were also noted on the largest fibre. Furthermore, we noted that the incorporation of extracellular matrix (ECM) had minimal effect on cell viability, both in normoxic and hypoxic culture conditions. Our results showed that these environments had limited influences on hypoxic gene expression. Interestingly, the major findings from this study was the production of excretory ECM components as shown in the scanning electron microscopy (SEM) images. The results from this study suggest that fibre diameter had a bigger impact on the seeded HUVECs than the incorporation of ECM or the culture conditions. The largest fibre dimeter (4.83 μm) is more suitable for seeding of HUVECs.

Mechanical and biological characterization of a composite annulus fibrosus repair strategy in an endplate delamination model.

This study compares the mechanical response of the commonly used annulus fibrosus (AF) puncture injury model of the intervertebral disc (IVD) and a newly proposed AF failure at the endplate junction (delamination) on ex vivo bovine IVDs. Biocompatibility and mechanics of a newly developed repair strategy comprising of electrospun polycaprolactone (PCL) scaffold and fibrin‐genipin (FibGen) adhesive was tested on the delamination model. The study found no significant difference in the mechanical response to compressive loading between the two models. Primary goals of the repair strategy to create a tight seal on the damage area and restore mechanical properties, while showing minimal cytotoxicity, were broadly achieved. Postrepair, the IVDs showed a significant restoration of mechanical properties compared to the injured samples for the delamination model. The FibGen glue showed a limited toxicity in the AF and produced a resilient and mechanically stable seal on the damaged area.

Surface potential and roughness controlled cell adhesion and collagen formation in electrospun PCL fibers for bone regeneration

Surface potential of biomaterials is a key factor regulating cell responses, driving their adhesion and signaling in tissue regeneration. In this study we compared the surface and zeta potential of smooth and porous electrospun polycaprolactone (PCL) fibers, as well as PCL films, to evaluate their significance in bone regeneration. The ’ surface potential of the fibers was controlled by applying positive and negative voltage polarities during the electrospinning. The surface properties of the different PCL fibers and films were measured using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM), and the zeta potential was measured using the electrokinetic technique. The effect of surface potential on the morphology of bone cells was examined using advanced microcopy, including 3D reconstruction based on a scanning electron microscope with a focused ion beam (FIB-SEM). Initial cell adhesion and collagen formation were studied using fluorescence microscopy and Sirius Red assay respectively, while calcium mineralization was confirmed with energy-dispersive x-ray (EDX) and Alzarin Red staining. These studies revealed that cell adhesion is driven by both the surface potential and morphology of PCL fibers. Furthermore, the ability to tune the surface potential of electrospun PCL scaffolds provides an essential electrostatic handle to enhance cell-material interaction and cellular activity, leading to controllable morphological changes.

Efficient mesenchymal stem cell conversion to corneal keratocytes by the use of specific biomaterial and Cell Rev™ mSC diffKera media

Background & Aim Corneal blindness is a prevalent cause of vision loss, affecting approximately 4.9 million people worldwide (Flaxman et al, 2017). The demand for donor replacement corneas often exceeds the supply, requiring alternative treatment options. To achieve corneal function while minimizing the risks of donor rejection, we propose an autologous biomimetic cornea whereby patient-derived mesenchymal stem cells (MSCs) are converted to corneal-like cells on scaffolds that closely resemble the structure of the human cornea. We hypothesize that the effectiveness of cell differentiation depends on the biomaterials used and the cultured media composition. The more closely the environment resembles that of the human cornea, the higher the likelihood that a greater proportion of MSCs will differentiate into corneal keratocytes. Methods, Results & Conclusion Here, we investigated MSC differentiation into corneal keratocytes using various medium formulations on our electrospun scaffolds. Polycaprolactone-bovine dermis type I atelocollagen (PCL-atelocollagen) and polycaprolactone (PCL) solutions were electrospun to obtain the aligned nanofibrous scaffolds. MSCs were cultured on the scaffolds for 12 days in 3 different types of media: the expansion media described by Lynch & Ahearne (2007); keratocyte differentiation media used in the same study; and our Cell Rev™ mSC diffKera media. Immunofluorescence staining for keratocyte markers such as aldehyde dehydrogenase 1 and lumican was conducted on cells fixed on the scaffolds at days 6 and 12. The results confirmed that a greater proportion of MSCs differentiated into keratocytes in Cell Rev™ mSC diffKera media compared with the media used by Lynch & Ahearne (Figure 1). In addition, electrospun PCL-atelocollagen scaffolds are likely to support keratocyte differentiation better than electrospun PCL scaffolds (control) because corneal stromal collagen fibrils comprise mainly type I collagen. These findings demonstrate that the use of our electrospun PCL-atelocollagen scaffolds and Cell Rev™ mSC diffKera formulation effectively enhances MSC differentiation into keratocytes, and represents a novel step for the creation of artificial corneas. Corneal blindness is a prevalent cause of vision loss, affecting approximately 4.9 million people worldwide (Flaxman et al, 2017). The demand for donor replacement corneas often exceeds the supply, requiring alternative treatment options. To achieve corneal function while minimizing the risks of donor rejection, we propose an autologous biomimetic cornea whereby patient-derived mesenchymal stem cells (MSCs) are converted to corneal-like cells on scaffolds that closely resemble the structure of the human cornea. We hypothesize that the effectiveness of cell differentiation depends on the biomaterials used and the cultured media composition. The more closely the environment resembles that of the human cornea, the higher the likelihood that a greater proportion of MSCs will differentiate into corneal keratocytes. Here, we investigated MSC differentiation into corneal keratocytes using various medium formulations on our electrospun scaffolds. Polycaprolactone-bovine dermis type I atelocollagen (PCL-atelocollagen) and polycaprolactone (PCL) solutions were electrospun to obtain the aligned nanofibrous scaffolds. MSCs were cultured on the scaffolds for 12 days in 3 different types of media: the expansion media described by Lynch & Ahearne (2007); keratocyte differentiation media used in the same study; and our Cell Rev™ mSC diffKera media. Immunofluorescence staining for keratocyte markers such as aldehyde dehydrogenase 1 and lumican was conducted on cells fixed on the scaffolds at days 6 and 12. The results confirmed that a greater proportion of MSCs differentiated into keratocytes in Cell Rev™ mSC diffKera media compared with the media used by Lynch & Ahearne (Figure 1). In addition, electrospun PCL-atelocollagen scaffolds are likely to support keratocyte differentiation better than electrospun PCL scaffolds (control) because corneal stromal collagen fibrils comprise mainly type I collagen. These findings demonstrate that the use of our electrospun PCL-atelocollagen scaffolds and Cell Rev™ mSC diffKera formulation effectively enhances MSC differentiation into keratocytes, and represents a novel step for the creation of artificial corneas.

Electrospun Antimicrobial, Anti‐Inflammatory and Analgesic Bandages for Comprehensive Wound Treatment

Chronic wounds affect more than 5 million Americans annually with an associated cost of $10 – 20 billion. These wounds provide perfect environments for bacterial growth, and are prone to infections, especially from multi‐drug resistant (MDR) pathogens. The current silver‐based bandages used to treat wounds exhibit a high toxicity toward fibroblasts, and lack anti‐inflammatory and analgesic activity. Our work focuses on the development of bandages to address these unmet clinical needs. We have fabricated electrospun polycaprolactone (PCL) scaffolds, capable of aiding in the wound healing process, and with incorporation of Ag+IBU, a novel therapeutic. These scaffolds deliver the drug locally at a controlled rate to impede bacterial infections. We have further functionalized PCL scaffolds with addition of polyethylene glycol (PEG) to accelerate drug release. Scanning electron microscopy images have revealed that our drug loaded scaffolds have a smooth fiber morphology and fiber diameter that is ~1 μm. Scaffolds loaded with either 5% or 10% Ag+IBU (w/w) release 40% of the drug within the first 24 hours. Microbiological assays have revealed that Ag+IBU‐loaded scaffolds are bactericidal against bacteria in both planktonic and biofilm growth mode. Cytotoxicity assays have revealed that Ag+IBU‐loaded scaffolds exhibit toxicity toward human dermal fibroblasts at high concentrations. However, pre‐incubation with N‐acetyl cysteine (NAC), an antioxidant metabolite, abrogates this toxicity and significantly increases cell viability. We have fabricated two‐layer scaffolds with one layer rapidly delivering NAC and the second layer slowly releasing Ag+IBU. Compared with the commercially available bandages with antimicrobial properties currently used for wounds, our non‐toxic, antimicrobial, anti‐inflammatory, and analgesic scaffolds offer a more comprehensive treatment option.Support or Funding InformationThis research is supported by NIH grant 5R21AI142327‐02

Vascularization and biocompatibility of poly(ε-caprolactone) fiber mats for rotator cuff tear repair.

Rotator cuff tear is the most frequent tendon injury in the adult population. Despite current improvements in surgical techniques and the development of grafts, failure rates following tendon reconstruction remain high. New therapies, which aim to restore the topology and functionality of the interface between muscle, tendon and bone, are essentially required. One of the key factors for a successful incorporation of tissue engineered constructs is a rapid ingrowth of cells and tissues, which is dependent on a fast vascularization. The dorsal skinfold chamber model in female BALB/cJZtm mice allows the observation of microhemodynamic parameters in repeated measurements in vivo and therefore the description of the vascularization of different implant materials. In order to promote vascularization of implant material, we compared a porous polymer patch (a commercially available porous polyurethane based scaffold from Biomerix™) with electrospun polycaprolactone (PCL) fiber mats and chitosan-graft-PCL coated electrospun PCL (CS-g-PCL) fiber mats in vivo. Using intravital fluorescence microscopy microcirculatory parameters were analyzed repetitively over 14 days. Vascularization was significantly increased in CS-g-PCL fiber mats at day 14 compared to the porous polymer patch and uncoated PCL fiber mats. Furthermore CS-g-PCL fiber mats showed also a reduced activation of immune cells. Clinically, these are important findings as they indicate that the CS-g-PCL improves the formation of vascularized tissue and the ingrowth of cells into electrospun PCL scaffolds. Especially the combination of enhanced vascularization and the reduction in immune cell activation at the later time points of our study points to an improved clinical outcome after rotator cuff tear repair.

An atmospheric pressure plasma jet to tune the bioactive peptide coupling to polycaprolactone electrospun layers

The surface chemistry of scaffolds for tissue regeneration can guide cells growth. In this study, we present a novel method to functionalize electrospun Polycaprolactone (PCL) scaffolds allowing the tuning of biomolecule superficial concentration by varying only one process parameter. The method is based on the deposition of NH2 functional groups starting form (3-Aminopropyl) triethoxysilane (APTES) as precursor by a novel Atmospheric Pressure Plasma Jet (APPJ) and by a successive selective covalent linking of these amines with a synthetic Human Vitronectin adhesive cue (HVP). The addition, in the peptide C-terminus, of an aldehyde group ensures the selective ligation by alkylimino-de-oxo-bisubstitution between the primary amine and HVP. By this method, we managed to alter the HVP surface concentration just varying the deposition time of the plasma process; this resulted in different surface coverage of the plasma coating, which in turn led to diverse amount of linked HVP. Coating stability, morphology and coverage was assessed by infrared and photo-electron spectroscopies and by electron microscopy. As a function of the coverage a variation on peptide concentration was revealed by Total Nitrogen method and confirmed by biological assays, which demonstrated an increase of human osteoblasts viability as a function of peptide concentration.

Peracetic Acid Sterilization Induces Divergent Biological Response in Polymeric Tissue Engineering Scaffolds

Synthetic polymers offer control over composition, architecture, mechanical properties and degradation kinetics. Predictable sterilization of synthetic polymeric scaffolds made from low temperature melting polymers, remains a challenge to clinical translation. We previously demonstrated successful room temperature sterilization of electrospun polycaprolactone scaffolds (ePCL) using peracetic acid (PA). The current paper investigates the effects of PA sterilization on two different scaffolds types—ePCL and commercially available porous polystyrene (Alvetex®) scaffolds using mouse calvarial osteoblasts cell line (MC3T3) and Live-Dead Assay. We report cytotoxicity in PA-treated ePCL scaffolds (PA-ePCL), while control scaffolds strongly supported cell survival. Treatment of PA-ePCL scaffolds with known methods of PA residual elimination (sodium thiosulfate, catalase, washing and aeration) had minimal effect on MC3T3 survival. However, incubation in 80% ethanol for 30 min successfully eliminated the toxic PA residuals and restored scaffold cytocompatibility. On the other hand, PA treatment of Alvetex® scaffolds induced diametrically opposite effects: cell survival and proliferation was enhanced after PA exposure and these responses were reversed following ethanol wash. These results suggest that PA treatment can induce different biological effects based on polymer chemistry and scaffold architecture and presents interesting opportunities to modulate biological properties of tissue engineering scaffolds.

Programmed Release of Multimodal, Cross-Linked Vascular Endothelial Growth Factor and Heparin Layers on Electrospun Polycaprolactone Vascular Grafts.

Viable tissue-engineering small-diameter vascular grafts should support rapid growth of an endothelial cell layer and exhibit long-term antithrombogenic property. In this study, multiple layers of various bioactive molecules, such as vascular endothelial growth factor (VEGF) and heparin, on an electrospun polycaprolactone scaffold have been developed through repeated electrostatic adsorption self-assembly (up to 20 layers), followed by genipin cross-linking. Programmed and sustained release of biomolecules embedded within the multilayered structure can be triggered by matrix metallopeptidase 2 enzyme in vitro. The result is an early and full release of VEGF to promote rapid endothelialization on the intended vascular grafts, followed by a gradual but sustained release of heparin for long-term anticoagulation and antithrombogenicity. This method of forming a biologically responsive, multimodal delivery of VEGF and heparin is highly suitable for all hydrophobic surfaces and provides a promising way to meet the critical requirements of engineered small-diameter vascular grafts.

Influence of aorta extracellular matrix in electrospun polycaprolactone scaffolds

ABSTRACTCardiovascular disease is the leading cause of mortality worldwide. Therefore, new research strategies for the treatment of cardiovascular disease are required. Previously, extracellular matrices (ECMs) have been used alongside polymers to generate hybrid bioscaffolds. Herein, we propose combining aortic ECMs with a polycaprolactone electrospun scaffold and biomechanically evaluating the scaffolds. We electrospun three scaffolds with varying ECM concentrations and found that increasing the ECM concentration leads to decreased stiffness at low strains, increased elasticity at high strain, reduction in failure strain, and an increase in yield strength. We also noted a decrease in water droplet contact angle with the increasing ECM concentration. Furthermore, we found that all three scaffolds were capable of maintaining human umbilical vein endothelial cell attachment and survival. These findings show the wide spectrum of mechanical properties that can be achieved through the addition of different concentrations of ECM into the fibers. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48181.

Complex relationship between alumina and selenium-doped carbonated hydroxyapatite as the ceramic additives to electrospun polycaprolactone scaffolds for tissue engineering applications

The future of nanomedicine belongs to composite nanostructures with complex and precisely tailored synergistic interactions between individual components. A composite scaffold was fabricated by electrospinning ε-polycaprolactone microfibers containing dispersed alumina and selenite-doped carbonated hydroxyapatite (Se-CHAP). The effects of the two coexisting ceramic components were investigated by testing the composites using a range of experimental techniques, including diffractometric, vibrational spectroscopic, porosimetric, mechanical and biological ones. No preferential orientation of the microfibers in the scaffolds was detected, but the fiber diameters increased and their curliness decreased as a function of the weight ratio between alumina and Se-CHAP. Synergistic breaking of the polymeric structure occurred due to the interaction of alumina and Se-CHAP in the polymeric matrix. The density of the composites decreased as Se-CHAP replaced alumina, but porosity was maximal in the material containing equal amounts of the two ceramic components, reiterating the complex synergistic interaction between them. Mechanical properties exhibited an equally complex relationship, with the composition containing alumina and Se-CHAP in 3:1 wt ratio displaying the highest toughness and strain at break and the composition containing alumina and Se-CHAP in 1:1 weight ratio exhibiting the lowest tensile strength and Young's modulus, lower than the materials supplemented with only alumina and only Se-CHAP. In-vitro cell studies on the human fibroblast HFB4 cell line demonstrated that the cells grew and spread on all polymeric scaffolds, but the adhesion, spread and infiltration increased in direct proportion with the Se-CHAP phase content. Also, although no significant loss of viability was detected in cells grown on any of the composite matrices, thus proving their biocompatibility, the lowest viability was detected on the matrices supplemented with the two ceramic additives in 1:1 weight ratio. Overall, no single composition proved most optimal for all the properties analyzed – microstructural, porosimetric, mechanical, biological. Rather, a compromise must be made between these different properties in search of the composition with the most optimal performance, with the caveat that fine changes in the weight ratio between alumina and Se-CHAP could produce significant repercussions at the level of material properties. The variable weight ratio between the two ceramic additives, however, allows for the tuning of the material properties for the desired application. This fundamental principle can be taken advantage of in the further optimization of this and similar materials for clinical use.

Fabrication of bioactive glass particles composite porous fibers by combination of electrospinning and phase separation

In the present study, a porous electrospun polycaprolactone (PCL) scaffold incorporated with bioactive glass (BG) particles was fabricated by combining phase separation with electrospinning. Chloroform (CF) and dimethyl formamide (DMF) were used as good solvents, while dimethyl sulfoxide (DMSO) was used as a poor solvent to generate pores on the fiber surface. The effects of PCL concentration, DMSO amount and BG particles dosage on the surface morphology of electrospun fibers were investigated, respectively. Fibrous scaffolds with well-distributed pores and uniform diameter were successfully obtained by using 12% w/v PCL in solution with good/poor solvent ratios at 90% v/v. The addition of BG particles (<8%w/v)in electrospun solution did not lead to any deformation of the porous fibers. The porous fibrous scaffolds incorporated with BG particles may be a promising scaffolds for soft tissue engineering.

A comparative study on pre- and post-production plasma treatments of PCL films and nanofibers for improved cell-material interactions

In this work, an atmospheric pressure plasma jet (APPJ) has been used to modify a 5% polycaprolactone (PCL) solution, after which the PCL solution was spin coated or electrospun to generate PCL films and nanofibers respectively. The APPJ treatment was found to have no effects on the chemical and physical properties of the PCL films, however, a strong influence on the morphology of electrospun PCL nanofibers could be observed. PCL nanofibers generated from the pristine PCL solutions contained multiple beads, while the PCL nanofibrous material generated from the APPJ-treated solutions consisted of nicely elongated, beadless PCL nanofibers. This enhanced electrospinnability was attributed to the strongly increased solution conductivity induced by the APPJ exposure. The APPJ treatment was also found to have minor effects on the chemical composition and the wettability of the nanofibers, which could be linked to the different surface morphology. All investigated pristine and APPJ-treated films and nanofibers unfortunately possessed poor cell-material interactions as a result of their high hydrophobicity. To cope with this issue, after spin coating and electrospinning, a second surface modification treatment making use of a dielectric barrier discharge (DBD) sustained in argon was also conducted. These treatments were found to considerably increase the wettability of PCL films and nanofibers without affecting their surface morphology. The enhanced wettability was caused by the incorporation of CO functional surface groups by the performed DBD treatments. The treatments were also found to positively affect cell growth on PCL films and nanofibers, with the best cellular performance obtained for the APPJ/DBD-treated PCL nanofibers. A combination of plasma treatments can thus play a significant role in the preparation of ideal electrospun PCL scaffolds for tissue engineering applications.

Pamidronate-encapsulated electrospun polycaprolactone as a potential bone regenerative scaffold

This study explores the potential of electrospun polycaprolactone scaffolds for the controlled delivery of pamidronate disodium pentahydrate, an amino-bisphosphonate drug used for the treatment of osteoporosis. Major drawbacks associated with oral bisphosphonate therapy are its poor bioavailability and gastrointestinal side-effects. Herein, we used polycaprolactone, a well-known Food and Drug Administration–approved biomaterial, as the delivering vehicle for pamidronate disodium pentahydrate. Scaffolds based on polycaprolactone with three different formulations (1, 3, and 5 wt%) of pamidronate disodium pentahydrate were fabricated by electrospinning, and a comparative study was carried out to evaluate the effect of pamidronate disodium pentahydrate on physico-mechanical and biological properties of polycaprolactone. The observations from Fourier-transform infrared spectra and thermogravimetric analysis confirmed the successful incorporation of pamidronate disodium pentahydrate into polycaprolactone scaffolds. The study also revealed that pamidronate disodium pentahydrate–loaded scaffolds exhibited improved hydrophilicity as well as superior mechanical properties as depicted by the contact angle measurements and mechanical property evaluation. In vitro drug release studies of pamidronate disodium pentahydrate–loaded scaffolds in phosphate buffer saline at 37°C showed that all the scaffolds exhibited controlled release of pamidronate disodium pentahydrate. In vitro degradation studies further revealed that pamidronate disodium pentahydrate incorporated polycaprolactone scaffolds degraded faster as depicted by the fiber rupture and drop in mechanical properties. In vitro cell culture studies using human osteosarcoma cell lines demonstrated that pamidronate disodium pentahydrate–loaded polycaprolactone scaffolds were cytocompatible. The human osteosarcoma cells had favorable interaction with the scaffolds, and the viability of adhered cells was depicted by the fluorescein diacetate/propidium iodide staining. MTT assay further revealed enhanced cell viability on PCL/PDS3 scaffolds. Our findings bespeak that the pamidronate disodium pentahydrate–encapsulated electrospun polycaprolactone scaffolds have the potential to serve as a promising drug delivery vehicle for osteoporotic bone defect repair.

Co-culture cell-derived extracellular matrix loaded electrospun microfibrous scaffolds for bone tissue engineering

Cell-derived extracellular matrix (ECM) has been employed as scaffolds for tissue engineering, creating a biomimetic microenvironment that provides physical, chemical and mechanical cues for cells and supports cell adhesion, proliferation, migration and differentiation by mimicking their in vivo microenvironment. Despite the enhanced bioactivity of cell-derived ECM, its application as a scaffold to regenerate hard tissues such as bone is still hampered by its insufficient mechanical properties. The combination of cell-derived ECM with synthetic biomaterials might result in an effective strategy to enhance scaffold mechanical properties and structural support. Electrospinning has been used in bone tissue engineering to fabricate fibrous and porous scaffolds, mimicking the hierarchical organized fibrillar structure and architecture found in the ECM. Although the structure of the scaffold might be similar to ECM architecture, most of these electrospun scaffolds have failed to achieve functionality due to a lack of bioactivity and osteoinductive factors. In this study, we developed bioactive cell-derived ECM electrospun polycaprolactone (PCL) scaffolds produced from ECM derived from human mesenchymal stem/stromal cells (MSC), human umbilical vein endothelial cells (HUVEC) and their combination based on the hypothesis that the cell-derived ECM incorporated into the PCL fibers would enhance the biofunctionality of the scaffold. The aims of this study were to fabricate and characterize cell-derived ECM electrospun PCL scaffolds and assess their ability to enhance osteogenic differentiation of MSCs, envisaging bone tissue engineering applications. Our findings demonstrate that all cell-derived ECM electrospun scaffolds promoted significant cell proliferation compared to PCL alone, while presenting similar physical/mechanical properties. Additionally, MSC:HUVEC-ECM electrospun scaffolds significantly enhanced osteogenic differentiation of MSCs as verified by increased ALP activity and osteogenic gene expression levels. To our knowledge, these results describe the first study suggesting that MSC:HUVEC-ECM might be developed as a biomimetic electrospun scaffold for bone tissue engineering applications.

In vitro osteogenic differentiation of stem cells with different sources on composite scaffold containing natural bioceramic and polycaprolactone

Stem cells can be obtained from a variety of sources. To compare the effect of cell source on the osteogenic differentiation potential, buccal fat pad-derived mesenchymal stem cells (BFP-MSCs), bone marrow-derived MSCs (BM-MSCs) and unrestricted somatic stem cells (USSCs) with different accessibility in time and region, were cultured on bioceramic (Bio-Oss®) coated electrospun polycaprolactone (PCL) scaffold (PCL-Bio). After scaffold characterization, stem cells proliferation and osteogenic differentiation were investigated by MTT and Alizarin red staining, alkaline phosphatase activity, calcium content and gene expression assays. Proliferation rate of the stem cells was not significantly different with each other, only USSCs showed significantly lower proliferation rate while cultured on PCL-Bio; although, PCL-Bio showed better proliferation support in comparison with tissue culture plate and PCL. Mineralization of the BM-MSCs was significantly higher than others, while BFP-MSCs were close to it. Highest ALP activity was detected in BFP-MSCs cultured on PCL-Bio. USSCs demonstrated higher gene expression level in three genes, although differences were not huge compared to others. According to the results and due to the availability, facilitated preparation procedure and less patients suffering, BFP-MSCs have a better choice than BM-MSCs and USSCs for use in bone tissue engineering.

Characterization of biomimetic silicate- and strontium-containing hydroxyapatite microparticles embedded in biodegradable electrospun polycaprolactone scaffolds for bone regeneration

A significant need exists today to develop novel alternatives to traditional bone grafts. Here, we report the potential use of mechanochemically synthesized hydroxyapatite (HA), silicate-, or strontium-containing HA microparticles and microparticle aggregates in combination with polycaprolactone (PCL) as hybrid scaffolds for filling bone defects. The detailed characterization of scaffolds was performed with high-resolution synchrotron radiation–based microcomputed laminography, XRD, EDX, and FTIR. An in vitro cell-scaffold interaction analysis showed a significant improvement of cell spreading in the case of hybrid scaffolds with silicate- and Sr-containing HA. Scaffolds with Sr- and silicate-containing HA affected the expression of several genes involved in morphogenesis and transcription. Scaffolds with Sr-containing HA increased the expression of markers of the primary component of the extracellular matrix, and scaffolds with Sr-containing HA facilitated cell mineralization via an increase in osteocalcin production. The hybrid scaffolds with silicate- and Sr-containing HA microparticles exerted the highest antibacterial activity against gram-positive bacterium Staphylococcus aureus compared to the unmodified PCL scaffolds. Based on these findings, the obtained scaffolds with Sr- or silicate-containing HA are believed to hold promise for bone tissue regeneration as compared to scaffolds containing pure HA.

Electrospun PCL/cefuroxime scaffolds with custom tailored topography

The study focuses on the fabrication and properties evaluation of dual functional electrospun polycaprolactone scaffolds incorporating antibiotic drug cefuroxime and having custom tailored topography for the support of human cells to be used in tissue regeneration. The scaffolds were evaluated in regard to their morphology, total porosity, thermal properties, tensile properties and cells adhesion/growth, thus to define the effect of both drug content and physical architecture on the scaffolds properties. Both the addition of the drug and the scaffolds custom topography resulted in higher total porosity (up to 90%), while the fibers diameter highest reduction was up to 73%. The type of 3 D printed collector influenced scaffolds tensile properties, thus the increase of the tensile strength was due to the change of the central cylinder height in the hexagonal geometry of the collectors. Cells distribution and spreading on the electrospun scaffolds after 72 hours, showed that scaffolds with custom topography have more evenly scattered cells than the ones with random electrospun fibers. The study has demonstrated that both drug concentration and scaffolds target topography influenced the scaffolds properties and both can be optimized depending on scaffolds demands.