Fibrous Scaffolds Research Articles

Controlled Stiffness of Direct-Write, Near-Field Electrospun Gelatin Fibers Generates Differences in Tenocyte Morphology and Gene Expression.

Tendinopathy is a leading cause of mobility issues. Currently, the cell-matrix interactions involved in the development of tendinopathy are not fully understood. In vitro tendon models provide a unique tool for addressing this knowledge gap as they permit fine control over biochemical, micromechanical, and structural aspects of the local environment to explore cell-matrix interactions. In this study, direct-write, near-field electrospinning of gelatin solution was implemented to fabricate micron-scale fibrous scaffolds that mimic native collagen fiber size and orientation. The stiffness of these fibrous scaffolds was found to be controllable between 1 MPa and 8 MPa using different crosslinking methods (EDC, DHT, DHT+EDC) or through altering the duration of crosslinking with EDC (1 h to 24 h). EDC crosslinking provided the greatest fiber stability, surviving up to 3 weeks in vitro. Differences in stiffness resulted in phenotypic changes for equine tenocytes with low stiffness fibers (∼1 MPa) promoting an elongated nuclear aspect ratio while those on high stiffness fibers (∼8 MPa) were rounded. High stiffness fibers resulted in the upregulation of matrix metalloproteinase (MMPs) and proteoglycans (possible indicators for tendinopathy) relative to low stiffness fibers. These results demonstrate the feasibility of direct-written gelatin scaffolds as tendon in vitro models and provide evidence that matrix mechanical properties may be crucial factors in cell-matrix interactions during tendinopathy formation.

3D Poly (L-lactic acid) fibrous sponge with interconnected porous structure for bone tissue scaffold

Large bone defects, often resulting from trauma and disease, present significant clinical challenges. Electrospun fibrous scaffolds closely resembling the morphology and structure of natural ECM are highly interested in bone tissue engineering. However, the traditional electrospun fibrous scaffold has some limitations, including lacking interconnected macropores and behaving as a 2D scaffold. To address these challenges, a sponge-like electrospun poly(L-lactic acid) (PLLA)/polycaprolactone (PCL) fibrous scaffold has been developed by an innovative and convenient method (i.e., electrospinning, homogenization, progen leaching and shaping). The resulting scaffold exhibited a highly porous structure (overall porosity = 85.9 %) with interconnected, regular macropores, mimicking the natural extracellular matrix. Moreover, the incorporation of bioactive glass (BG) particles improved the hydrophilicity (water contact angle = 79.7°) and biocompatibility and promoted osteoblast cell growth. In-vitro 10-day experiment revealed that the scaffolds led to high cell viability. The increment of the proliferation rates was 195.4 % at day 7 and 281.6 % at day 10. More importantly, Saos-2 cells could grow, proliferate, and infiltrate into the scaffold. Therefore, this 3D PLLA/PCL with BG sponge holds great promise for bone defect repair in tissue engineering applications.

The procoagulant signature of cancer cells drives fibrin network formation in tumor microenvironment and impacts its quality. Implications in cancer cell migration and the resistance to anticancer agents

IntroductionCancer cells induce hypercoagulability in the tumoral microenvironment by expressing Tissue Factor (TF). We aimed to study the impact of the procoagulant signature of cancer cells on the quality and structure of fibrin network. We also studied the impact of fibrin clot shield (FCS) on the efficiency of anticancer agents and the migration of cancer cells. Materials and methodsPancreatic cancer cells BXPC3 and breast cancer cells MDA-MB231 and MCF7, were cultured in the presence of normal Platelet Poor Plasma (PPP), diluted 10 % in conditioning media. Their potential to induce thrombin generation and their fibrinolytic activity were assessed. The structure of fibrin network was analyzed with Scanning Electron Microscopy (SEM). Cancer cells' mobility with fibrin clot and their interactions with fibrin were observed. Cancer cells were treated with paclitaxel (PTX) or 4-hydroxy-tamoxifen (4OHTam) in the presence or absence of FCS. ResultsCancer cells, in presence of PPP, induced fibrin network formation. High TF-expressing cancer cells (BXPC3 and MDA-MB23 cells), led to dense fibrin network with fine fibers. Low TF expressing cells MCF7 led to thick fibers. Exogenous TF enhanced the density of fibrin network formed by MCF7 cells. Cancer cells through their inherent profibrinolytic potential migrated within the fiber scaffold. The BXPC3 and MCF7 cells moved in clusters whereas the MDA-MB231 cells moved individually within the fibrin network. FCS decreased the efficiency of PTX and 4OHTam on the viability of cancer cells. ConclusionsThe procoagulant signature of cancer cells is determinant for the quality and structure of fibrin network in the microenvironment. Original SEM images show the architecture of “bird's nest”-like fibrin network being in touch with the cell membranes and surrounding cancer cells. Fibrin network constructed by triggering thrombin generation by cancer cells, provides a scaffold for cell migration. Fibrin clot shields protect cancer cells against PTX and 4OHTam.

Platelet-rich fibrin as an autologous biomaterial for bone regeneration: mechanisms, applications, optimization.

Platelet-rich fibrin, a classical autologous-derived bioactive material, consists of a fibrin scaffold and its internal loading of growth factors, platelets, and leukocytes, with the gradual degradation of the fibrin scaffold and the slow release of physiological doses of growth factors. PRF promotes vascular regeneration, promotes the proliferation and migration of osteoblast-related cells such as mesenchymal cells, osteoblasts, and osteoclasts while having certain immunomodulatory and anti-bacterial effects. PRF has excellent osteogenic potential and has been widely used in the field of bone tissue engineering and dentistry. However, there are still some limitations of PRF, and the improvement of its biological properties is one of the most important issues to be solved. Therefore, it is often combined with bone tissue engineering scaffolds to enhance its mechanical properties and delay its degradation. In this paper, we present a systematic review of the development of platelet-rich derivatives, the structure and biological properties of PRF, osteogenic mechanisms, applications, and optimization to broaden their clinical applications and provide guidance for their clinical translation.

Functionalization of PCL-Based Fiber Scaffolds with Different Sources of Calcium and Phosphate and Odontogenic Potential on Human Dental Pulp Cells.

This study investigated the incorporation of sources of calcium, phosphate, or both into electrospun scaffolds and evaluated their bioactivity on human dental pulp cells (HDPCs). Additionally, scaffolds incorporated with calcium hydroxide (CH) were characterized for degradation, calcium release, and odontogenic differentiation by HDPCs. Polycaprolactone (PCL) was electrospun with or without 0.5% w/v of calcium hydroxide (PCL + CH), nano-hydroxyapatite (PCL + nHA), or β-glycerophosphate (PCL + βGP). SEM/EDS analysis confirmed fibrillar morphology and particle incorporation. HDPCs were cultured on the scaffolds to assess cell viability, adhesion, spreading, and mineralized matrix formation. PCL + CH was also evaluated for gene expression of odontogenic markers (RT-qPCR). Data were submitted to ANOVA and Student's t-test (α = 5%). Added CH increased fiber diameter and interfibrillar spacing, whereas βGP decreased both. PCL + CH and PCL + nHA improved HDPC viability, adhesion, and proliferation. Mineralization was increased eightfold with PCL + CH. Scaffolds containing CH gradually degraded over six months, with calcium release within the first 140 days. CH incorporation upregulated DSPP and DMP1 expression after 7 and 14 days. In conclusion, CH- and nHA-laden PCL fiber scaffolds were cytocompatible and promoted HDPC adhesion, proliferation, and mineralized matrix deposition. PCL + CH scaffolds exhibit a slow degradation profile, providing sustained calcium release and stimulating HDPCs to upregulate odontogenesis marker genes.

3D cotton-type anisotropic biomimetic scaffold with low fiber motion electrospun via a sharply inclined array collector for induced osteogenesis

Electrospinning is an effective method to fabricate fibrous scaffolds that mimic the ECM of bone tissue on a nano- to macro-scale. However, a limitation of electrospun fibrous scaffolds for bone tissue engineering is the structure formed by densely compacted fibers, which significantly impedes cell infiltration and tissue ingrowth. To address this problem, several researchers have developed numerous techniques for fabricating 3D fibrous scaffolds with customized topography and pore size. Despite the success in developing various 3D electrospun scaffolds based on fiber repulsion, the lack of contact points between fibers in those scaffolds has been shown to hinder cell attachment, migration, proliferation, and differentiation due to excessive movement of the fibers. In this article, we introduce a Dianthus caryophyllus-inspired scaffold fabricated using SIAC-PE, a modified collector under specific viscosity conditions of PCL/LA solution. The developed scaffold mimicking the structural similarities of the nature-inspired design presented enhanced cell proliferation, infiltration, and increased expression of bone-related factors by reducing fiber movements, presenting high space interconnection, high porosity, and controlled fiber topography.

Three-Dimensional Microfibrous Scaffold with Aligned Topography Produced via a Combination of Melt-Extrusion Additive Manufacturing and Porogen Leaching for In Vitro Skeletal Muscle Modeling.

Skeletal muscle tissue (SMT) has a highly hierarchical and anisotropic morphology, featuring aligned and parallel structures at multiple levels. Various factors, including trauma and disease conditions, can compromise the functionality of skeletal muscle. The in vitro modeling of SMT represents a useful tool for testing novel drugs and therapies. The successful replication of SMT native morphology demands scaffolds with an aligned anisotropic 3D architecture. In this work, a 3D PCL fibrous scaffold with aligned morphology was developed through the synergistic combination of Melt-Extrusion Additive Manufacturing (MEAM) and porogen leaching, utilizing PCL as the bulk material and PEG as the porogen. PCL/PEG blends with different polymer ratios (60/40, 50/50, 40/60) were produced and characterized through a DSC analysis. The MEAM process parameters and porogen leaching in bi-distilled water allowed for the development of a micrometric anisotropic fibrous structure with fiber diameters ranging from 10 to 100 µm, depending on PCL/PEG blend ratios. The fibrous scaffolds were coated with Gelatin type A to achieve a biomimetic coating for an in vitro cell culture and mechanically characterized via AFM. The 40/60 PCL/PEG scaffolds yielded the most homogeneous and smallest fibers and the greatest physiological stiffness. In vitro cell culture studies were performed by seeding C2C12 cells onto a selected scaffold, enabling their attachment, alignment, and myotube formation along the PCL fibers during a 14-day culture period. The resultant anisotropic scaffold morphology promoted SMT-like cell conformation, establishing a versatile platform for developing in vitro models of tissues with anisotropic morphology.

Additively manufactured 3D short carbon fiber scaffold for thermoset composites

Short-fiber-reinforced polymer composites offer advantages, like flexibility in complex geometries and cost-effectiveness, but typically exhibit lower mechanical properties because of the random orientation of short fibers. In this work, a novel process utilizing shear force to create 3D scaffold with customized fiber alignment for the manufacturing of short carbon fibers (SCF)-reinforced thermoset composites has been presented. The Computed tomography test confirmed the alignment of the SCF along printing directions. The results demonstrate that the aligned SCF-reinforced epoxy composites exhibited a 190% improvement in tensile strength and 388% improvement in tensile modulus compared to neat epoxy.Graphical abstract

Polyhydroxybutyrate-based osteoinductive mineralized electrospun structures that mimic components and tissue interfaces of the osteon for bone tissue engineering.

Scaffolds for bone tissue engineering should enable regeneration of bone tissues with its native hierarchically organized ECM and multiple tissue interfaces. To achieve this, inspired by the structure and properties of bone osteon, we fabricated polyhydroxybutyrate-based mineralized electrospun fibrous scaffolds. After studying multiple polyhydroxybutyrate (PHB)-based fibers, we chose 7%PHB/1%Gelatin fibers (PG) to fabricate mineralized fibers that mimic mineralized collagen fibers in bone. The mineralized PG (mPG) surface had a rough, hydrophilic layer of low crystalline calcium phosphate which was biocompatible to BMSCs, induced their proliferation and was osteoinductive. Subsequently, by modulating the electrospinning process, we fabricated mPG-based novel higher order fibrous scaffolds that mimic the macroscale geometries of osteons of bone ECM. Inspired by the aligned collagen fibers in bone lamellae, we fabricated mPG scaffolds with aligned fibers that could direct anisotropic elongation of mBMSCs. Further, we fabricated electrospun mPG-based osteoinductive tubular constructs which can mimic cylindrical bone components like osteons or lamellae or be used as long bone analogues based on their dimensions. Finally, to regenerate tissue interfaces in bone, we introduced a novel bi-layered scaffold-based approach. An electrospun bi-layered tubular construct that had PG in the outer layer and 7%PHB/0.5%Polypyrrole fibers (PPy) in the inner layer was fabricated. The bi-layered tubular construct underwent preferential surface mineralization only on its outer layer. This outer mineralized layer supported osteogenesis while the inner PPy layer could support neural cell growth. Thus, the bi-layered tubular construct may be used to regenerate haversian canal in the osteons which hosts nerve fibers. Overall, the study introduced novel techniques to fabricate biomimetic structures that can regenerate components of bone osteon and its multiple tissue interfaces. The study lays foundation for the fabrication of a modular scaffold that can regenerate bone with its hierarchical structure and complex tissue interfaces.

The fabrication method impacts biological properties of microfibrous three-dimensional in vitro cell culture scaffolds and their applications in drug screening

Two-dimensional (2D) cell culture models cannot accurately emulate the three-dimensional (3D) in vivo microenvironment; hence, the shift from compound screening in traditional 2D well plates to 3D cell culture models is forthcoming. New scaffold designs must comply with the 3Rs principle to reduce the use of animal-derived products, such as natural proteins. In line with this motivation, we engineered and compared various fibrous scaffolds featuring diverse fibre networks (coarse and fine fibres) and fibre surface properties (porous vs. smooth fibres), and tested them in in vitro cell culture. We fabricated coarse solid fibre scaffolds via a melt-based electrohydrodynamic process, which resulted in fibres with a diameter of 10.6 ± 1.9 µm and a porosity of 87.1 ± 0.9%. Using solution-based cryo-electrohydrodynamic process, we fabricated fine porous fibre and fine solid fibre scaffolds that exhibited fibres of 2.01 ± 0.5 µm and 1.72 ± 0.6 µm in diameter, with porosities of 96.5 ± 0.3% and 94.4 ± 0.5%, respectively. The scaffolds underwent only chemical modification via an alkaline treatment to enhance their hydrophilicity. We used mouse fibroblast L929 cells and human triple-negative breast cancer MDA-MB-231 cells as cell models, and used the MTT assay to measure their viability. After seven days of cell culture, all scaffolds were thoroughly penetrated. However, the coarse scaffolds created by the melt-based electrohydrodynamic process and the porous fibre scaffolds produced by the solution-based cryo-electrohydrodynamic process outperformed the simpler morphology of smooth fine fibres. Furthermore, the 50% half-maximum effective concentration (EC50) of doxorubicin tested in human glioblastoma (U87-MG) and human triple-negative breast cancer (MDA-MB-231) cell lines in 3D cell culture models was approximately twice as high as that achieved in conventional 2D cell cultures. Therefore, we infer that poly (ɛ-caprolactone) (PCL) microfibre scaffolds, devoid of animal-derived product surface treatment, may provide a favourable 3D milieu for various cell types for in vitro studies.

Automated brightfield layerwise evaluation in three-dimensional micropatterning via two-photon polymerization.

Two-photon polymerization (TPP) is an advanced 3D fabrication technique capable of creating features with submicron precision. A primary challenge in TPP lies in the facile and accurate characterization of fabrication quality, particularly for structures possessing complex internal features. In this study, we introduce an automated brightfield layerwise evaluation technique that enables a simple-to-implement approach for in situ monitoring and quality assessment of TPP-fabricated structures. Our approach relies on sequentially acquired brightfield images during the TPP writing process and using background subtraction and image processing to extract layered spatial features. We experimentally validate our method by printing a fibrous tissue scaffold and successfully achieve an overall system-adjusted fidelity of 87.5% in situ. Our method is readily adaptable in most TPP systems and can potentially facilitate high-quality TPP manufacturing of sophisticated microstructures.

Impact of the Reduction Time-Dependent Electrical Conductivity of Graphene Nanoplatelet-Coated Aligned Bombyx mori Silk Scaffolds on Electrically Stimulated Axonal Growth.

Graphene-based nanomaterials, renowned for their outstanding electrical conductivity, have been extensively studied as electroconductive biomaterials (ECBs) for electrically stimulated tissue regeneration. However, using eco-friendly reducing agents like l-ascorbic acid (l-Aa) can result in lower conductive properties in these ECBs, limiting their full potential for smooth charge transfer in living tissues. Moreover, creating a flexible biomaterial scaffold using these materials that accurately mimics a specific tissue microarchitecture, such as nerves, poses additional challenges. To address these issues, this study developed a microfibrous scaffold of Bombyx mori (Bm) silk fibroin uniformly coated with graphene nanoplatelets (GNPs) through a vacuum coating method. The scaffold's electrical conductivity was optimized by varying the reduction period using l-Aa. The research systematically investigated how different reduction periods impact scaffold properties, focusing on electrical conductivity and its significance on electrically stimulated axonal growth in PC12 cells. Results showed that a 48 h reduction significantly increased surface electrical conductivity by 100-1000 times compared to a shorter or no reduction process. l-Aa contributed to stabilizing the reduced GNPs, demonstrated by a slow degradation profile and sustained conductivity even after 60 days in a proteolytic environment. β (III) tubulin immunostaining of PC12 cells on varied silk:GNP scaffolds under pulsed electrical stimulation (ES, 50 Hz frequency, 1 ms pulse width, and amplitudes of 100 and 300 mV/cm) demonstrates accelerated axonal growth on scaffolds exhibiting higher conductivity. This is supported by upregulated intracellular Ca2+ dynamics immediately after ES on the scaffolds with higher conductivity, subjected to a prolonged reduction period. The study showcases a sustainable reduction approach using l-Aa in combination with natural Bm silk fibroin to create a highly conductive, mechanically robust, and stable silk:GNP-based aligned fibrous scaffold. These scaffolds hold promise for functional regeneration in electrically excitable tissues such as nerves, cardiac tissue, and muscles.

Platelet rich fibrin and simvastatin-loaded pectin-based 3D printed-electrospun bilayer scaffold for skin tissue regeneration

Designing multifunctional wound dressings is a prerequisite to prevent infection and stimulate healing. In this study, a bilayer scaffold (BS) with a top layer (TL) comprising 3D printed pectin/polyacrylic acid/platelet rich fibrin hydrogel (Pec/PAA/PRF) and a bottom nanofibrous layer (NL) containing Pec/PAA/simvastatin (SIM) was produced. The biodegradable and biocompatible polymers Pec and PAA were cross-linked to form hydrogels via Ca2+ activation through galacturonate linkage and chelation, respectively. PRF as an autologous growth factor (GF) source and SIM together augmented angiogenesis and neovascularization. Because of 3D printing, the BS possessed a uniform distribution of PRF in TL and an average fiber diameter of 96.71 ± 18.14 nm was obtained in NL. The Young's modulus of BS was recorded as 6.02 ± 0.31 MPa and its elongation at break was measured as 30.16 ± 2.70 %. The wound dressing gradually released growth factors over 7 days of investigation. Furthermore, the BS significantly outperformed other groups in increasing cell viability and in vivo wound closure rate (95.80 ± 3.47 % after 14 days). Wounds covered with BS healed faster with more collagen deposition and re-epithelialization. The results demonstrate that the BS can be a potential remedy for skin tissue regeneration.

Fabrication of Silk Fibroin‐Derived Fibrous Scaffold for Biomedical Frontiers

AbstractSilk fibroin (SF), a natural protein derived from silkworms, has emerged as a promising biomaterial due to its biocompatibility, biodegradability, degradation rate, and tunable mechanical properties. This review delves into the intrinsic attributes of SF that make it an attractive candidate for scaffold development in tissue engineering and regenerative medicine. The distinctiveness of this comprehensive review resides in its detailed exploration of recent advancements in the fabrication techniques of SF‐based fibrous scaffolds, namely electrospinning, freeze‐drying, and 3D printing. An in‐depth analysis of these fabrication techniques is conducted to illustrate their versatility in customizing essential scaffold characteristics, such as porosity, fiber diameter, and mechanical strength. The article meticulously discusses process parameters, advantages, and challenges of each fabrication technique, highlighting the innovative advancements made in the respective field. Furthermore, the review goes beyond fabrication techniques to provide an overview of the latest biomedical applications and research endeavors utilizing SF‐derived scaffolds. From nerve regeneration and wound healing to drug delivery, bone regeneration, and vascular tissue engineering, the diverse applications underscore the versatility of SF in adopting various biomedical challenges. Finally, the article emphasizes the need for standardized characterization techniques, scalable manufacturing processes, and long‐term in vivo studies.

Tunable electrospun scaffolds of polyacrylonitrile loaded with carbon nanotubes: from synthesis to biological applications.

Growing cells in a biomimetic environment is critical for tissue engineering as well as for studying the cell biology underlying disease mechanisms. To this aim a range of 3D matrices have been developed, from hydrogels to decellularized matrices. They need to mimic the extracellular matrix to ensure the optimal growth and function of cells. Electrospinning has gained in popularity due to its capacity to individually tune chemistry and mechanical properties and as such influence cell attachment, differentiation or maturation. Polyacrylonitrile (PAN) derived electrospun fibres scaffolds have shown exciting potential due to reports of mechanical tunability and biocompatibility. Building on previous work we fabricate here a range of PAN fibre scaffolds with different concentrations of carbon nanotubes. We characterize them in-depth in respect to their structure, surface chemistry and mechanical properties, using scanning electron microscopy, image processing, ultramicrotomic transmission electron microscopy, x-ray nanotomography, infrared spectroscopy, atomic force microscopy and nanoindentation. Together the data demonstrate this approach to enable finetuning the mechanical properties, while keeping the structure and chemistry unaltered and hence offering ideal properties for comparative studies of the cellular mechanobiology. Finally, we confirm the biocompatibility of the scaffolds using primary rat cardiomyocytes, vascular smooth muscle (A7r5) and myoblast (C2C12) cell lines.

Stepwise degradable PGA-SF core-shell electrospinning scaffold with superior tenacity in wetting regime for promoting bone regeneration

Regenerating bone in the oral and maxillofacial region is clinically challenging due to the complicated osteogenic environment and the limitation of existing bone graft materials. Constructing bone graft materials with controlled degradation and stable mechanical properties in a physiological environment is of utmost importance. In this study, we used silk fibroin (SF) and polyglycolic acid (PGA) to fabricate a coaxial PGA-SF fibrous scaffold (PGA-SF-FS) to meet demands for bone grafts. The SF shell exerted excellent osteogenic activity while protecting PGA from rapid degradation and the PGA core equipped scaffold with excellent tenacity. The experiments related to biocompatibility and osteogenesis (e.g., cell attachment, proliferation, differentiation, and mineralization) demonstrated the superior ability of PGA-SF-FS to improve cell growth and osteogenic differentiation. Furthermore, in vivo testing using Sprague-Dawley rat cranial defect model showed that PGA-SF-FS accelerates bone regeneration as the implantation time increases, and its stepwise degradation helps to match the remodeling kinetics of the host bone tissue. Besides, immunohistochemical staining of CD31 and Col-1 confirmed the ability of PGA-SF-FS to enhance revascularization and osteogenesis response. Our results suggest that PGA-SF-FS fully utilizing the advantages of both components, exhibites stepwise degradation and superior tenacity in wetting regime, making it a promising candidate in the treatment of bone defects.

Hierarchical porous poly (L-lactic acid) fibrous vascular graft with controllable architectures and stable structure

Electrospun fibre has shown great potential in tissue engineering and regenerative medicine due to its high specific surface area and extracellular matrix-mimicking structure. However, fabricating an electrospun fibrous scaffold with controllable complex 3D macroscopic configuration remains a challenge. In the present study, a novel method was designed to transform 2D electrospun poly (L-lactic acid) (PLLA) fibrous membrane to tubular PLLA fibrous scaffolds with 3D complex but tailored configuration. The electrospun PLLA fibrous membrane was rolled around a designed mould and then treated with acetone. Treated vascular grafts’ length, diameter, and shape can be tailored by the mould parameters. Moreover, treated vascular grafts achieve favourable mechanical properties (Young’s modulus = 155 MPa, tensile stress = 8.79 MPa and radial force = 2.2 N) and the mechanical properties could be engineered on demand. In addition, treated vascular grafts kept their initial structure and size during long-term in vitro experiments once they were formed. In addition, with the acetone-induced recrystallization of PLLA, pristine solid PLLA fibres were changed to hierarchical porous PLLA fibres with ultra-high specific surface area (28.9 m2/g) and wettability (water contact angle = 101.32°), which has positive effects on cell adhesion and proliferation ability. A7r5 in vitro experiment shows that the proliferation rate of treated vascular grafts increased 153% at day 4 and 170.6% at day 7 compared with pristine vascular grafts.

The role of BSA protein on the skin regeneration ability of electrospun PCL/HA scaffolds, kinetics of release and essential in vitro tests

This study focused on the skin regeneration ability of hybrid polycaprolactone (PCL) scaffolds incorporated by hydroxyapatite (HA) nanoparticles (NPs) and bovine serum albumin (BSA). The scaffolds were synthesized by the electrospinning method, and their microstructure, molecular groups, wettability, swelling, porosity, and mechanical properties were characterized. The results showed that the HA NPs and BSA protein could be incorporated within the PCL fibers without a significant effect on the main molecular groups of the PCL structure. Incorporation of both the HA NPs and BSA protein could reduce the superhydrophobicity of the PCL scaffold to the required amount for skin regeneration. It was also found that the incorporation of mentioned elements increased the water uptake by PCL fibrous scaffolds, and decreased the mechanical properties. The kinetics of BSA release from the hybrid scaffolds was also investigated. The Higuchi model was the best-fitting model to explain the protein release from the electrospun products. The cytocompatibility of scaffolds was evaluated by the human umbilical vein endothelial cells (HUVEC), and the higher ability of the PCL/BSA scaffold for skin regeneration was confirmed.

Tailorable mechanical and degradation properties of KCl-reticulated and BDDE-crosslinked PCL/chitosan/κ-carrageenan electrospun fibers for biomedical applications: Effect of the crosslinking-reticulation synergy

The development of intricated and interconnected porous mats is desired for many applications in biomedicine and other relevant fields. The mats that comprise the use of natural, bioactive, and biodegradable polymers are the focus of current research activities. In the present work, crosslinked fibers with improved characteristics were produced by incorporating 1,4-butanediol diglycidyl ether (BDDE) into a polymer formulation containing polycaprolactone (PCL), chitosan (CS), and κappa-carrageenan (κ-C). A slight variation of formic acid (FA)/acetic acid (AA) ratio used as a solvent system, significantly affected the characteristics of the produced fiber mats. Both polysaccharides and BDDE played a major role in tailoring mechanical properties when fibrous scaffolds were reticulated under KCl-mediated basic conditions for determined periods of time at 50 °C. In vitro biological assessment of the electrospun fiber mats revealed proliferation of MC3T3-E1 cells when incubated for 1 and 7 days. After staining the cells with 4′,6-diamidino-2-phenylindole (DAPI)/rhodamine phalloidin an autofluorescence response was observed by fluorescence microscopy in the scaffold manufactured using a solvent with higher FA/AA ratio due to the formation of microfibers. The results demonstrated the potential of the BDDE-crosslinked PCL/CS/κ-C electrospun fibers as promising materials for biomedical applications that may include soft and bone tissue regeneration.

First Advanced Bilayer Scaffolds for Tailored Skin Tissue Engineering Produced via Electrospinning and Melt Electrowriting

AbstractIn vitro skin models are validated methods for screening cosmetics and pharmaceuticals, but still have limitations. The bilayer poly(ε‐caprolactone) scaffold/membrane model described here overcomes some of these deficits by integrating a solution electrospun (SES) membrane at the dermoepidermal interface and a melt electrowritten (MEW) scaffold that provides an optimal open‐pore environment for the dermis. To the knowledge, this scaffold/membrane model is the only one capable of creating a properly differentiated, full thickness skin model with neosynthesized extracellular matrix (ECM) in only 18 days. Both the wavy and straight fiber scaffold designs create a well‐organized dermis, but dermal collagen organization differs between designs. Adding cells and vitamin C to the scaffolds improves the mechanical properties to more closely mimic native human skin. These findings establish bicomponent scaffolds as a promising advancement for rapidly creating different skin models with varied properties. The versatility and adaptability of the described model can be used for studying how the biological and physical microenvironment impact skin, and testing dermo‐cosmetics and pharmaceutical treatments on different ages of skin. Furthermore, it can be an excellent new tool for studying wound healing and development into its use as a graft or wound dressing is ongoing.