Electrospun P(LLA-CL) nanofiber: a biomimetic extracellular matrix for smooth muscle cell and endothelial cell proliferation

Biomimetic Approaches in Scaffold-Based Blood Vessel Tissue Engineering

Cardiovascular diseases remain a leading cause of mortality globally, with atherosclerosis representing a significant pathological means, often leading to myocardial infarction. Coronary artery bypass surgery, a common procedure used to treat coronary artery disease, presents challenges due to the limited autologous tissue availability or the shortcomings of synthetic grafts. Consequently, there is a growing interest in tissue engineering approaches to develop vascular substitutes. This review offers an updated picture of the state of the art in vascular tissue engineering, emphasising the design of scaffolds and dynamic culture conditions following a biomimetic approach. By emulating native vessel properties and, in particular, by mimicking the three-layer structure of the vascular wall, tissue-engineered grafts can improve long-term patency and clinical outcomes. Furthermore, ongoing research focuses on enhancing biomimicry through innovative scaffold materials, surface functionalisation strategies, and the use of bioreactors mimicking the physiological microenvironment. Through a multidisciplinary lens, this review provides insight into the latest advancements and future directions of vascular tissue engineering, with particular reference to employing biomimicry to create systems capable of reproducing the structure-function relationships present in the arterial wall. Despite the existence of a gap between benchtop innovation and clinical translation, it appears that the biomimetic technologies developed to date demonstrate promising results in preventing vascular occlusion due to blood clotting under laboratory conditions and in preclinical studies. Therefore, a multifaceted biomimetic approach could represent a winning strategy to ensure the translation of vascular tissue engineering into clinical practice.

Ferulic acid's therapeutic odyssey: nano formulations, pre-clinical investigations, and patent perspective

INTRODUCTION

Ferulic acid (FA) is a phenolic phytochemical that has garnered the attention of the research community due to its abundant availability in nature. It is a compound that has been explored for its multifaceted therapeutic potential and benefits in modern and contemporary healthcare.

AREAS COVERED

This review furnishes a compilation of the molecular mechanisms underlying the anti-diabetic, anticancer, antioxidant, and anti-inflammatory effects of FA. We also aim to excavate an in-depth analysis of the role of nanoformulations to achieve release control, reduce toxicity, and deliver FA at specified target sites. To corroborate the safety and efficacy of FA, a multitude of pre-clinical studies have also been conducted by researchers and have been discussed comprehensively in this review. The various patented innovations and newer paradigms pertaining to FA have also been presented.

EXPERT OPINION

Enormous research has been conducted and should still be continued to find the best possible novel drug delivery system for FA delivery. The utilization of nanocarriers and nanoformulations has intrigued the scientists for delivery of FA, but before that, it is necessary to shed light upon toxicity, safety, and regulatory concerns of FA.

Nano-biomaterial Fibrinogen/P(LLA-CL) for prevention of intrauterine adhesion and restoration of fertility

Endometrial damage resulting from surgical procedures is a significant cause of intrauterine adhesion, thin endometrium, and subsequent miscarriage and infertility. Unfortunately, there is currently no effective clinical solution to promote endometrial regeneration after severe injury. In this study, we combined fibrinogen (Fg) and P(LLA-CL) by electrostatic spinning to form a stable nano-biomaterial Fg/P(LLA-CL), which can promote endometrial regeneration. After inducing physical injury to rat endometrium, we found that Fg/P(LLA-CL) membranes placed in the uterine cavities increased endometrial thickness and the number of glands after injury, while reducing the area of endometrial fibrosis. In addition, Fg/P(LLA-CL) increased neovascularization and decreased COL1A1 deposition. The expression of TGF-β1, a cytokine that promotes fibrosis, was down-regulated in the early stage of injury. Finally, fertility assays confirmed that Fg/P(LLA-CL) improved the pregnancy rate in rats with endometrial injury, and its safety was verified by blood tests and pathological examination of heart, liver, spleen, lung, and kidney. Therefore, Fg/P(LLA-CL) shows great potential as a safe and nontoxic biomaterial for endometrial regeneration, ultimately improving pregnancy outcomes in patients with intrauterine adhesion.

MXene-Decorated Nanofibrous Membrane with Programmed Antibacterial and Anti-Inflammatory Effects via Steering NF-κB Pathway for Infectious Cutaneous Regeneration

Although antibiotic is still the main choice for antibacteria both in hospital and community, phototherapy has become a possibly one of the alternative approaches in the treatment of microbe-associated infections nowadays because of its considerable potential in effective eradication of pathogenic bacteria. However, overwhelming reactive oxygen species (ROS) generated from phototherapy inevitably provoke an inflammatory response, complicating the healing process. To address this outstanding issue, a MXene-decorated nanofibrious is devised that not only yield localized heat but also elevate ROS levels under near-infrared laser exposure ascribed to the synergistic photothermal/photodynamic effect, for potent bacterial inactivation. After being further loaded with aspirin, the nanofibrous membranes exhibit benign cytocompatibility, boosting cell growth and suppressing the (nuclear factor kappa-B ( NF-κB) signaling pathways through RNA sequencing analysis, indicating an excellent anti-inflammatory effect. Interestingly, in vivo investigations also corroborate that the nanofibrous membranes accelerate infectious cutaneous regeneration by efficiently killing pathogenic bacteria, promoting collagen deposition, boosting angiogenesis, and dampening inflammatory reaction via steering NF-κB pathway. As envisaged, this work furnishes a decorated nanofibrous membrane with programmed antibacterial and anti-inflammatory effects for remedy of refractory bacteria-invaded wound regeneration.

An Overview of Scaffolds and Biomaterials for Skin Expansion and Soft Tissue Regeneration: Insights on Zinc and Magnesium as New Potential Key Elements

The utilization of materials in medical implants, serving as substitutes for non-functional biological structures, supporting damaged tissues, or reinforcing active organs, holds significant importance in modern healthcare, positively impacting the quality of life for millions of individuals worldwide. However, certain implants may only be required temporarily to aid in the healing process of diseased or injured tissues and tissue expansion. Biodegradable metals, including zinc (Zn), magnesium (Mg), iron, and others, present a new paradigm in the realm of implant materials. Ongoing research focuses on developing optimized materials that meet medical standards, encompassing controllable corrosion rates, sustained mechanical stability, and favorable biocompatibility. Achieving these objectives involves refining alloy compositions and tailoring processing techniques to carefully control microstructures and mechanical properties. Among the materials under investigation, Mg- and Zn-based biodegradable materials and their alloys demonstrate the ability to provide necessary support during tissue regeneration while gradually degrading over time. Furthermore, as essential elements in the human body, Mg and Zn offer additional benefits, including promoting wound healing, facilitating cell growth, and participating in gene generation while interacting with various vital biological functions. This review provides an overview of the physiological function and significance for human health of Mg and Zn and their usage as implants in tissue regeneration using tissue scaffolds. The scaffold qualities, such as biodegradation, mechanical characteristics, and biocompatibility, are also discussed.

Human Keratinocytes and Fibroblasts Co-Cultured on Silk Fibroin Scaffolds Exosomally Overrelease Angiogenic and Growth Factors

Objectives: The optimal healing of skin wounds, deep burns, and chronic ulcers is an important clinical problem. Attempts to solve it have been driving the search for skin equivalents based on synthetic or natural polymers. Methods: Consistent with this endeavor, we used regenerated silk fibroin (SF) from Bombyx mori to produce a novel compound scaffold by welding a 3D carded/hydroentangled SF-microfiber-based nonwoven layer (C/H-3D-SFnw; to support dermis engineering) to an electrospun 2D SF nanofiber layer (ESFN; a basal lamina surrogate). Next, we assessed-via scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, mono- and co-cultures of HaCaT keratinocytes and adult human dermal fibroblasts (HDFs), dsDNA assays, exosome isolation, double-antibody arrays, and angiogenesis assays-whether the C/H-3D-SFnws/ESFNs would allow the reconstitution of a functional human skin analog in vitro. Results: Physical analyses proved that the C/H-3D-SFnws/ESFNs met the requirements for human soft-tissue-like implants. dsDNA assays revealed that co-cultures of HaCaTs (on the 2D ESFN surface) and HDFs (inside the 3D C/H-3D-SFnws) grew more intensely than did the respective monocultures. Double-antibody arrays showed that the CD9⁺/CD81⁺ exosomes isolated from the 14-day pooled growth media of HDF and/or HaCaT mono- or co-cultures conveyed 35 distinct angiogenic/growth factors (AGFs). However, versus monocultures' exosomes, HaCaT/HDF co-cultures' exosomes (i) transported larger amounts of 15 AGFs, i.e., PIGF, ANGPT-1, bFGF, Tie-2, Angiogenin, VEGF-A, VEGF-D, TIMP-1/-2, GRO-α/-β/-γ, IL-1β, IL-6, IL-8, MMP-9, and MCP-1, and (ii) significantly more strongly stimulated human dermal microvascular endothelial cells to migrate and assemble tubes/nodes in vitro. Conclusions: Our results showed that both cell-cell and cell-SF interactions boosted the exosomal release of AGFs from HaCaTs/HDFs co-cultured on C/H-3D-SFnws/ESFNs. Hence, such exosomes are an asset for prospective clinical applications as they advance cell growth and neoangiogenesis and consequently graft take and skin healing. Moreover, this new integument analog could be instrumental in preclinical and translational studies on human skin pathophysiology and regeneration.

Synergetic Effect of Electrical and Topographical Cues in Aniline Trimer-Based Polyurethane Fibrous Scaffolds on Tissue Regeneration

Processibility and biodegradability of conductive polymers are major concerns when they are applied to tissue regeneration. This study synthesizes dissolvable and conductive aniline trimer-based polyurethane copolymers (DCPU) and processes them into scaffolds by using electrospinning with different patterns (random, oriented, and latticed). The effects of topographic cue changes on electrical signal transmission and further regulation of cell behaviors concerning bone tissue are researched. Results show that DCPU fibrous scaffolds possessed good hydrophilicity, swelling capacity, elasticity, and fast biodegradability in enzymatic liquid. In addition, the conductivity and efficiency of electrical signal transmission can be tuned by changing the surface’s topological structure. Among them, oriented DCPU scaffolds (DCPU-O) showed the best conductivity with the lowest ionic resistance value. Furthermore, the viability and proliferation results of bone mesenchymal stem cells (BMSCs) demonstrate a significant increase on three DCPU scaffolds compared to AT-free scaffolds (DPU-R). Especially, DCPU-O scaffolds exhibit superior abilities to promote cell proliferation because of their unique surface topography and excellent electroactivity. Concurrently, the DCPU-O scaffolds can synergistically promote osteogenic differentiation in terms of osteogenic differentiation and gene expression levels when combined with electrical stimulation. Together, these results suggest a promising use of DCPU-O fibrous scaffolds in the application of tissue regeneration.

Intersection of nanomaterials and organoids technology in biomedicine

Organoids are stem cell-derived, self-organizing, 3D structures. Compared to the conventional 2D cell culture method, 3D cultured organoids contain a variety of cell types that can form functional "micro-organs" and can be used to simulate the occurrence process and physiological pathological state of organ tissues more effectively. Nanomaterials (NMs) are becoming indispensable in the development of novel organoids. Understanding the application of nanomaterials in organoid construction can, therefore, provide researchers with ideas for the development of novel organoids. Here, we discuss the application status of NMs in various organoid culture systems and the research direction of NMs combined with organoids in the biomedical field.

Resorbable Nanomatrices from Microbial Polyhydroxyalkanoates: Design Strategy and Characterization

From a series of biodegradable natural polymers of polyhydroxyalkanoates (PHAs)-poly-3-hydroxybutyrate (P(3HB) and copolymers containing, in addition to 3HB monomers, monomers of 3-hydroxyvalerate (3HV), 3-hydroxyhexanoate (3HHx), and 4-hydroxybutyrate (4HB), with different ratios of monomers poured-solvent casting films and nanomembranes with oriented and non-oriented ultrathin fibers were obtained by electrostatic molding. With the use of SEM, AFM, and measurement of contact angles and energy characteristics, the surface properties and mechanical and biological properties of the polymer products were studied depending on the method of production and the composition of PHAs. It has been shown in cultures of mouse fibroblasts of the NIH 3T3 line and diploid human embryonic cells of the M22 line that elastic films and nanomembranes composed of P(3HB-co-4HB) copolymers have high biocompatibility and provide adhesion, proliferation and preservation of the high physiological activity of cells for up to 7 days. Polymer films, namely oriented and non-oriented nanomembranes coated with type 1 collagen, are positively evaluated as experimental wound dressings in experiments on laboratory animals with model and surgical skin lesions. The results of planimetric measurements of the dynamics of wound healing and analysis of histological sections showed the regeneration of model skin defects in groups of animals using experimental wound dressings from P(3HB-co-4HB) of all types, but most actively when using non-oriented nanomembranes obtained by electrospinning. The study highlights the importance of nonwoven nanomembranes obtained by electrospinning from degradable low-crystalline copolymers P(3HB-co-4HB) in the effectiveness of the skin wound healing process.

Tuning structural-response of PLA/PCL based electrospun nanofibrous mats: Role of dielectric-constant and electrical-conductivity of the solvent system

The role of optimum solvent systems on the fabrication of uniform, bead-free electrospun-nanofibrous-mats (ENMs) of polylactic acid (PLA), poly(ε-caprolactone) (PCL), and their blends, is investigated. The solvent systems influenced the fiber-diameters, morphology, crystallinity, thermal stability, hydrophobicity, quasi-static mechanical, and solid-state visco-elastic responses of the ENMs. Defect-free ENMs were obtained by using CF/DMF (80:20 v/v) binary solvent system while showing a relatively higher extent of crystallinity (PLA/PCL blend ∼ 34%), lower hydrophobicity (PLA ∼ 117⁰), higher strength (PLA ∼ 6 MPa), and moduli (PLA ∼ 305 MPa) for PLA and PLA/PCL blend systems whereas a higher strain-at-break (∼ 82%) was shown by PCL based ENMs. PLA/PCL blend based ENMs fabricated using DCM/DMF (80:20 v/v) solvent-mixture exhibited comparatively lower crystallinity (∼ 25%) but higher fiber diameter (1.03 ± 0.21 µm), strain-at-break (∼ 155%), and hydrophobicity (∼ 130⁰) compared to CF/DMF (80:20 v/v) system. Dynamic mechanical analysis (DMA) revealed the structural relaxation behaviors indicating the intrinsic structural deformability and flexibility of the mats. The study demonstrated the systematic role of solvent characteristics in terms of their volatility, dielectric constant, and solvent-mixture composition on the electro-spinnability and fabrication of high-strength, deformable, hydrophobic, bead-free ENMs with near monodisperse fibrous assemblies for biomedical applications.

Electrospun Scaffolds Functionalized with a Hydrogen Sulfide Donor Stimulate Angiogenesis

Tissue-engineered constructs are currently limited by the lack of vascularization necessary for the survival and integration of implanted tissues. Hydrogen sulfide (H2S), an endogenous signaling gas (gasotransmitter), has been recently reported as a promising alternative to growth factors to mediate and promote angiogenesis in low concentrations. Yet, sustained delivery of H2S remains a challenge. Herein, we have developed angiogenic scaffolds by covalent attachment of an H2S donor to a polycaprolactone (PCL) electrospun scaffold. These scaffolds were engineered to include azide functional groups (on 1, 5, or 10% of the PCL end groups) and were modified using a straightforward click reaction with an alkyne-functionalized N-thiocarboxyanhydride (alkynyl-NTA). This created H2S-releasing scaffolds that rely on NTA ring-opening in water followed by conversion of released carbonyl sulfide into H2S. These functionalized scaffolds showed dose-dependent release of H2S based on the amount of NTA functionality within the scaffold. The NTA-functionalized fibrous scaffolds supported human umbilical vein endothelial cell (HUVEC) proliferation, formed more confluent endothelial monolayers, and facilitated the formation of tight cell-cell junctions to a greater extent than unfunctionalized scaffolds. Covalent conjugation of H2S donors to scaffolds not only promotes HUVEC proliferation in vitro, but also increases neovascularization in ovo, as observed in the chick chorioallantoic membrane assay. NTA-functionalized scaffolds provide localized control over vascularization through the sustained delivery of a powerful endogenous angiogenic agent, which should be further explored to promote angiogenesis in tissue engineering.

Gelatin Blends Enhance Performance of Electrospun Polymeric Scaffolds in Comparison to Coating Protocols

The electrospinning of hybrid polymers is a versatile fabrication technique which takes advantage of the biological properties of natural polymers and the mechanical properties of synthetic polymers. However, the literature is scarce when it comes to comparisons of blends regarding coatings and the improvements offered thereby in terms of cellular performance. To address this, in the present study, nanofibrous electrospun scaffolds of polycaprolactone (PCL), their coating and their blend with gelatin were compared. The morphology of nanofibrous scaffolds was analyzed under field emission scanning electron microscopy (FE-SEM), indicating the influence of the presence of gelatin. The scaffolds were mechanically tested with tensile tests; PCL and PCL gelatin coated scaffolds showed higher elastic moduli than PCL/gelatin meshes. Viability of mouse embryonic fibroblasts (MEF) was evaluated by MTT assay, and cell proliferation on the scaffold was confirmed by fluorescence staining. The positive results of the MTT assay and cell growth indicated that the scaffolds of PCL/gelatin excelled in comparison to other scaffolds, and may serve as good candidates for tissue engineering applications.

Development and Characterization of Multifunctional Wound Dressing with the Property of Anti-bacteria and Angiogenesis

Overcoming the bacterial infection and promoting angiogenesis are challenge and imperious demands in wound healing and skin regeneration. Hereby, we developed a multifunctional AMP/S1P@PLA/gelatin wound dressing fabricated by electrospinning poly (L-lactic acid) (PLA)/gelatin with antimicrobial polypeptides (AMPs) and sphingosine-1-phosphate (S1P) in order to inhibit the bacteria growth and induce angiogenesis. In our work, AMP/S1P@PLA/gelatin wound dressing was obtained by two-step method of electrospinning and dopamine adsorption. Our results showed that incorporating AMP into PLA/gelatin nanofibrous membranes significantly improved antibacterial properties against both Escherichia coli and Staphylococcus aureus. S1P releasing from AMP/S1P@PLA/gelatin nanofibrous membranes could significantly enhance tube formation. Simultaneously, we found that the AMP/S1P@PLA/gelatin nanofibrous membranes facilitated the adhesion, proliferation, and migration of human umbilical vein endothelial cells (HUVECs) and murine fibroblast (L929). AMP/S1P@PLA/gelatin membranes could also accelerate infected wound healing and skin regeneration by antibacterial and pro-angiogenesis effects. In summary, our developed AMP/S1P@PLA/gelatin nanofibrous membranes could be multifunctional dressing for infected wound healing and skin regeneration. Schematic figure to describe the characterizations and preparation of AMP/S1P@PLA/gelatin nanofibrous membranes.

Cellulosic-Based Conductive Hydrogels for Electro-Active Tissues: A Review Summary

The use of hydrogel in tissue engineering is not entirely new. In the last six decades, researchers have used hydrogel to develop artificial organs and tissue for the diagnosis of real-life problems and research purposes. Trial and error dominated the first forty years of tissue generation. Nowadays, biomaterials research is constantly progressing in the direction of new materials with expanded capabilities to better meet the current needs. Knowing the biological phenomenon at the interaction among materials and the human body has promoted the development of smart bio-inert and bio-active polymeric materials or devices as a result of vigorous and consistent research. Hydrogels can be tailored to contain properties such as softness, porosity, adequate strength, biodegradability, and a suitable surface for adhesion; they are ideal for use as a scaffold to provide support for cellular attachment and control tissue shapes. Perhaps electrical conductivity in hydrogel polymers promotes the interaction of electrical signals among artificial neurons and simulates the physiological microenvironment of electro-active tissues. This paper presents a review of the current state-of-the-art related to the complete process of conductive hydrogel manufacturing for tissue engineering from cellulosic materials. The essential properties required by hydrogel for electro-active-tissue regeneration are explored after a short overview of hydrogel classification and manufacturing methods. To prepare hydrogel from cellulose, the base material, cellulose, is first synthesized from plant fibers or generated from bacteria, fungi, or animals. The natural chemistry of cellulose and its derivatives in the fabrication of hydrogels is briefly discussed. Thereafter, the current scenario and latest developments of cellulose-based conductive hydrogels for tissue engineering are reviewed with an illustration from the literature. Finally, the pro and cons of conductive hydrogels for tissue engineering are indicated.

Hyaluronic acid and chitosan-based electrospun wound dressings: Problems and solutions

To date, available review papers related to the electrospinning of biopolymers including polysaccharides for wound healing were focused on summarizing the process conditions for two candidates, namely chitosan and hyaluronic acid. However, most reviews lack the discussion of problems of hyaluronan and chitosan electrospun nanofibers for wound dressing applications. For this reason, it is required to update information by providing a comprehensive overview of all factors which may play a role in the electrospinning of hyaluronic acid and chitosan for applications of wound dressings. This review summarizes the fabricated chitosan and hyaluronic acid electrospun nanofibers as wound dressings in the last years, including methods of preparations of nanofibers and challenges for the electrospinning of both pure chitosan and hyaluronic acid and strategies how to overcome the existing difficulties. Moreover, in this review the biological roles and mechanisms of chitosan and hyaluronic acid in the wound healing process are explained including the advantages of nanofibers for ideal wound management using the common solvents, copolymers enhancing spinning process, and the most biologically active incorporated substances thereby providing drug delivery in wound healing.

Nematic Templated Complex Nanofiber Structures by Projection Display

Oriented arrays of nanofibers are ubiquitous in nature and have been widely used in recreation of the biological functions such as bone and muscle tissue regenerations. However, it remains a challenge to produce nanofiber arrays with a complex organization by using current fabrication techniques such as electrospinning and extrusion. In this work, we propose a method to fabricate the complex organization of nanofiber structures templated by a spatially varying ordered liquid crystal host, which follows the pattern produced by a maskless projection display system. By programming the synchronization of the rotated polarizer and projected segments with different shapes, various configurations of nanofiber organization ranging from a single to two-dimensional lattice of arbitrary topological defects are created in a deterministic manner. The nanofiber arrays can effectively guide and promote neurite outgrowth. The application of nanofibers with arced profiles and topological defects on neural tissue organization is also demonstrated. This finding, combined with the versatility and programmability of nanofiber structures, suggests that they will help solve challenges in nerve repair, neural regeneration, and other related tissue engineering fields.

Understanding multiscale structure-property correlations in PVDF-HFP electrospun fiber membranes by SAXS and WAXS

Electrospinning is a versatile technique to produce nanofibrous membranes with applications in filtration, biosensing, biomedical and tissue engineering. The structural and therefore physical properties of electrospun fibers can be finely tuned by changing the electrospinning parameters. The large parameter window makes it challenging to optimize the properties of fibers for a specific application. Therefore, a fundamental understanding of the multiscale structure of fibers and its correlation with their macroscopic behaviors is required for the design and production of systems with dedicated applications. In this study, we demonstrate that the properties of poly(vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) electrospun fibers can be tuned by changing the rotating drum speed used as a collector during electrospinning. Indeed, with the help of multiscale characterization techniques such as scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS), we observe that increasing the rotating drum speed not only aligns the fibers but also induces polymeric chain rearrangements at the molecular scale. Such changes result in enhanced mechanical properties and an increase of the piezoelectric β-phase of the PVDF-HFP fiber membranes. We detect nanostructural deformation behaviors when the aligned fibrous membrane is uniaxially stretched along the fiber alignment direction, while an increase in the alignment of the fibers is observed for randomly aligned samples. This was analyzed by performing in situ SAXS measurements coupled with uniaxial tensile loading of the fibrous membranes along the fiber alignment direction. The present study shows that fibrous membranes can be produced with varying degrees of fiber orientation, piezoelectric β-phase content, and mechanical properties by controlling the speed of the rotating drum collector during the fiber production. Such aligned fiber membranes have potential applications for neural or musculoskeletal tissue engineering.

Multifunctional Membranes-A Versatile Approach for Emerging Pollutants Removal

This paper presents a comprehensive literature review surveying the most important polymer materials used for electrospinning processes and applied as membranes for the removal of emerging pollutants. Two types of processes integrate these membrane types: separation processes, where electrospun polymers act as a support for thin film composites (TFC), and adsorption as single or coupled processes (photo-catalysis, advanced oxidation, electrochemical), where a functionalization step is essential for the electrospun polymer to improve its properties. Emerging pollutants (EPs) released in the environment can be efficiently removed from water systems using electrospun membranes. The relevant results regarding removal efficiency, adsorption capacity, and the size and porosity of the membranes and fibers used for different EPs are described in detail.

Assessment of structural, biological and drug release properties of electro-sprayed poly lactic acid-dexamethasone coating for biomedical applications

The efficacy of an implant is highly depends on its coating characteristics mainly determined by polymer properties and coating technique. Electro-spraying is an inexpensive and versatile coating technique with various advantages for biomedical application. In this study, the efficacy of electro-sprayed (ES) poly lactic acid (PLA)-dexamethasone (DEX) coatings for medical implants was evaluated and compared with spin-coated samples as control. Structural properties of coatings were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Confocal and scanning electron microscopy (SEM), contact angle measurement and nanoindentation tests were used to study surface properties. Coating degradation rate and drug release profile were studied for 40 days. Cell viability experiments were also performed on human endothelial (HUVEC) and smooth muscle cells (HUASMC) using MTT assay and SEM. XRD and DSC analysis showed electro-spraying significantly reduce PLA and DEX crystallinity. Surface studies showed ES coatings has significantly higher hydrophobicity and roughness with microbead-nanofiber morphology vs. micro-nanoporous structure of spin-coated samples. Initial burst release of DEX was 22% and 10% after 6 h and total release was 71% and 46% after 40 days for ES and spin-coated samples, respectively. HUVEC viability of ES samples was higher than spin-coated ones after 1 and 4 days. However, dexamethasone release profile reduced HUASMC proliferation in ES PLA-DEX samples in comparison to spin-coated after 1 and 3 days. In conclusion, in vitro results showed potential of ES PLA-DEX as a biocompatible and efficient anti-inflammatory coating with suitable drug release profile for future applications such as coronary drug eluting stents.

A review on allopathic and herbal nanofibrous drug delivery vehicles for cancer treatments

Drug delivery empowered with nanotechnology manifests to be a superior therapy to cancer. Electrospun nanofibers cocooning anti-cancerous drugs have shown tremendous cytotoxicity towards various tumor cells, including breast, brain, liver, and lung cancer cells. This pristine drug delivery system, according to literature, desists showing any undesirable effects on other parts of the body and bestows several other benefits. From nature-derived Curcumin to laboratory-made Doxorubicin, literature proclaims many such drugs used in nanofibrous drug delivery. Also, multi-drug delivery has been reported to exhibit enhanced properties. The present review exhibits the unrealized potential of nanofibrous drug delivery in chemotherapy.

Versatility of unsaturated polyesters from electrospun macrolactones: RGD immobilization to increase cell attachment

Poly(globalide) (PGl), an aliphatic polyester derived from unsaturated macrocylic lactone, can be cross-linked during electrospinning and drug-loaded for regenerative medicine applications. However, it lacks intrinsic recognition sites for cell adhesion and proliferation. In order to improve their cell adhesiveness, and therefore their therapeutic potential, we aimed to functionalize electrospun PGl fibers with RGD sequence generating a biomimetic scaffold. First, an amine compound was attached to the surface double bonds of the PGl fibers. Subsequently, the amino groups were coupled with RGD sequences. X-ray photoelectron spectroscopy (XPS) analysis confirmed the functionalization. The obtained fibers were more hydrophilic, as observed by contact angle analysis, and presented smaller Young's modulus, although similar tensile strength compared with non-functionalized cross-linked fibers. In addition, the functionalization process did not significantly alter fibers morphology, as observed by scanning electron microscopy (SEM). Finally, in vitro analysis evidenced the increase in human mesenchymal stromal cells (hMSC) adhesion (9.88 times higher DNA content after 1 day of culture) and proliferation (3.57 times higher DNA content after 8 days of culture) compared with non-functionalized non-cross-linked fibers. This is the first report demonstrating the functionalization of PGl fibers with RGD sequence, improving PGl therapeutic potential and further corroborating the use of this highly versatile material toward regenerative medicine applications.

A novel substrate based on electrospun polyurethane nanofibers and electrosprayed polyvinyl alcohol microparticles for recombinant human erythropoietin delivery

After myocardial infarction caused by a heart attack, endothelial cells need to be preserved in order to regenerate new capillaries. Moreover, sufficient mechanical support is necessary for the infarcted myocardium to pump the blood. Herein, we designed a novel substrate containing polyurethane (PU) nanofibrous layers and recombinant human erythropoietin (rhEPO)-loaded microparticles for both controlled releases of rhEPO and mechanical support of myocardium. In this system, the single-layer (SL) and double-layer (DL) PU nanofibers were electrospun, and then microparticles with different rhEPO:polyvinyl alcohol (PVA) ratios were electrosprayed on the layers. The in vitro release behavior of rhEPO from SL substrates was not satisfactory, and then the study focused on DL patches in which the release profile was in accordance with Korsmeyer-Peppas model. The release exponent of 0.89 for the DL PU/120PVA:1rhEPO represented zero-order release. The results inferred that these substrates possessed highly tailored mechanical properties; Young's modulus and ultimate tensile strength of the substrates were 74-172 kPa and 7.4-9.9 MPa, respectively. The rhEPO release from the substrates was leading to the proper adhesion of endothelial cells and more than 95% cell viability. The results indicated that the patch of elastic nanofibers and microparticles offered a potential substrate for simultaneous rhEPO delivery to endothelial cells and also mechanically supporting the infarcted myocardium.

Porous polymeric membranes: fabrication techniques and biomedical applications

Porous polymeric membranes have shown great potential in biological and biomedical applications such as tissue engineering, bioseparation, and biosensing, due to their structural flexibility, versatile surface chemistry, and biocompatibility. This review outlines the advantages and limitations of the fabrication techniques commonly used to produce porous polymeric membranes, with especial focus on those featuring nano/submicron scale pores, which include track etching, nanoimprinting, block-copolymer self-assembly, and electrospinning. Recent advances in membrane technology have been key to facilitate precise control of pore size, shape, density and surface properties. The review provides a critical overview of the main biological and biomedical applications of these porous polymeric membranes, especially focusing on drug delivery, tissue engineering, biosensing, and bioseparation. The effect of the membrane material and pore morphology on the role of the membranes for each specific application as well as the specific fabrication challenges, and future prospects of these membranes are thoroughly discussed.

Addition of glycerol enhances the flexibility of gelatin hydrogel sheets; application for in utero tissue engineering

Gelatin hydrogels are naturally derived scaffolds useful for tissue engineering because of their cytocompatibility and controllable degradability. However, they are brittle and inflexible when dry, which limits their use for in utero tissue engineering in large animal models. Therefore, in this study, we attempted to generate flexible gelatin sheets by adding various plasticizers with different molecular weights (MW). We systematically evaluated the flexibility, sustainability, and potential clinical utility of the resulting flexible gelatin sheets. Gelatin sheets with low-MW plasticizers, such as monosaccharides or sugar alcohols, showed a reduced tensile modulus in dynamic viscoelasticity, which reflected their actual flexibility. Wet gelatin sheets containing plasticizers showed higher tensile strength than the nonplasticizer control, although wet gelatin sheets under all conditions had a much lower tensile strength than dry gelatin sheets. In a functional study, gelatin sheets containing glycerol, which has the lowest MW among sugar alcohols, showed encouraging results, such as good fit to the curvature of the experimental animal, biocompatibility, and suitability for endoscopic approaches. The findings of this study should enable the expansion of future applications for flexible gelatin sheets.

In vivo performance of a bilayer wrap to prevent abdominal adhesions

There is a high prevalence of intra-abdominal adhesions following bowel resection, which can result in chronic pain, bowel obstruction, and morbidity. Although commercial adhesion barriers have been widely utilized for colonic resections, these barriers do not prevent anastomotic leakage resulting from reduced healing of the anastomosis, which can result in long-term health problems. To address this limitation, we have developed an adhesive bilayer wrap with selective bioactivity to simultaneously prevent intra-abdominal adhesion formation and promote anastomotic healing. Reactive electrospinning was used to generate a crosslinked gelatin mesh to serve as a cell-instructive substrate to improve anastomotic healing. A coating of poly(ethylene glycol) (PEG) foam was applied to the bioactive mesh to generate an antifouling layer and prevent intra-abdominal adhesions. After in vitro confirmation of selective bioactivity, the composite wrap was compared after 2 weeks to a commercial product (Interceed^Ⓡ) in an in vivo rat colonic abrasion model for prevention of intra-abdominal adhesions. The composite bilayer wrap was able to prevent intra-abdominal adhesions when clinical placement was maintained. The composite bilayer wrap was further modified to include tissue adhesive properties for improved efficacy. Preliminary studies indicated that the adhesive composite bilayer wrap maintained a maximum shear strength comparable to Interceed^Ⓡ and greater than fibrin glue. Overall, this work resulted in an initial proof-of-concept device that was shown to effectively prevent intra-abdominal adhesion formation in vivo. The composite bilayer wrap studied here could lead to an improved technology for improved healing of intestinal anastomoses.

Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

An atorvastatin calcium and poly(L-lactide-co-caprolactone) core-shell nanofiber-covered stent to treat aneurysms and promote reendothelialization

Aneurysmal subarachnoid hemorrhage is a common complication caused by an intracranial aneurysm that can lead to hemorrhagic stroke, brain damage, and death. Knowing this clinical situation, the purpose of this study was to develop a controlled-release stent covered with a core-shell nanofiber mesh, fabricated by emulsion electrospinning, for the treatment of aneurysms. By encapsulating atorvastatin calcium (AtvCa) in the inner of poly (L-lactide-co-caprolactone) (PLCL) nanofibers, the release period of AtvCa was effectively extended. The morphology and inner structure of the core-shell nanofibers were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The release of AtvCa from the nanofiber system continued for more than ten weeks without a significant initial burst release. The nanofiber mesh structure degraded gradually but maintained its fiber morphology before neovascularization. The results of this study further elucidated the reendothelialization mechanism of AtvCa by analyzing the nitric oxide (NO) expression from seeded HUVECs. The in vivo studies demonstrated that the PLCL-AtvCa covered stents were capable of separating the aneurysm dome from the blood circulation, leading to the abolishment of the aneurysm. Moreover, the AtvCa controlled release promoted the in vitro proliferation of HUVECs on the nanofiber meshes, and the PLCL-AtvCa covered stents induced in vivo neovascularization. STATEMENT OF SIGNIFICANCE: Intracranial aneurysms are pathological dilatations of blood vessels that have developed an abnormally weak wall structure, thus prone to rupture. Covered stents had been demonstrated to be a method for the treatment of intracranial aneurysm. We prepared a controlled-release stent covered with a core-shell nanofiber mesh, fabricated by emulsion electrospinning, which encapsulated atorvastatin calcium in the inner portion of nanofibers. The results of this study further elucidated the reendothelialization mechanism of AtvCa by analyzing the nitric oxide (NO) expression from seeded HUVECs. The generated AtvCa-load covered stents separated the aneurysm dome from the blood circulation, and keep long-term patency of the parent artery. But also induced neovascularization, thus provide further protection against recurrence of aneurysms after nanofiber meshes degradation.

Well-Blended PCL/PEO Electrospun Nanofibers with Functional Properties Enhanced by Plasma Processing

Biodegradable composite nanofibers were electrospun from poly(ε-caprolactone) (PCL) and poly(ethylene oxide) (PEO) mixtures dissolved in acetic and formic acids. The variation of PCL:PEO concentration in the polymer blend, from 5:95 to 75:25, revealed the tunability of the hydrolytic stability and mechanical properties of the nanofibrous mats. The degradation rate of PCL/PEO nanofibers can be increased compared to pure PCL, and the mechanical properties can be improved compared to pure PEO. Although PCL and PEO have been previously reported as immiscible, the electrospinning into nanofibers having restricted dimensions (250–450 nm) led to a microscopically mixed PCL/PEO blend. However, the hydrolytic stability and tensile tests revealed the segregation of PCL into few-nanometers-thin fibrils in the PEO matrix of each nanofiber. A synergy phenomenon of increased stiffness appeared for the high concentration of PCL in PCL/PEO nanofibrous mats. The pure PCL and PEO mats had a Young’s modulus of about 12 MPa, but the mats made of high concentration PCL in PCL/PEO solution exhibited 2.5-fold higher values. The increase in the PEO content led to faster degradation of mats in water and up to a 20-fold decrease in the nanofibers’ ductility. The surface of the PCL/PEO nanofibers was functionalized by an amine plasma polymer thin film that is known to increase the hydrophilicity and attach proteins efficiently to the surface. The combination of different PCL/PEO blends and amine plasma polymer coating enabled us to tune the surface functionality, the hydrolytic stability, and the mechanical properties of biodegradable nanofibrous mats.

Co-Culturing of Endothelial and Cancer Cells in a Nanofibrous Scaffold-Based Two-Layer System

Angiogenesis is critical for local tumor growth. This study aimed to develop a three-dimensional two-layer co-culture system to investigate effects of cancer cells on the growth of endothelial cells (ECs). Poly(ε-caprolactone) (PCL) nanofibrous membranes were generated via electrospinning of PCL in chloroform (C-PCL-M) and chloroform and dimethylformamide (C/DMF-PCL-M). We assembled a two-layer co-culture system using C-PCL-M and C/DMF-PCL-M for EC growth in the upper layer with co-cultured cancer cells in the lower layer. In the absence of vascular endothelial growth factor (VEGF), growth of bEND.3 ECs decreased on C/DMF-PCL-M but not on C-PCL-M with time. Growth of bEND.3 cells on C/DMF-PCL-M was enhanced through co-culturing of CT26 cancer cells and enhanced growth of bEND.3 cells was abrogated with anti-VEGF antibodies and sorafenib. However, EA.hy926 ECs displayed steady growth and proliferation on C/DMF-PCL-M, and their growth was not further increased through co-culturing of cancer cells. Moreover, chemical hypoxia in CT26 cancer cells upon treatment with CoCl₂ enhanced the growth of co-cultured bEND.3 cells in the two-layer system. Thus, EC growth on the nanofibrous scaffold is dependent on the types of ECs and composition of nanofibers and this co-culture system can be used to analyze EC growth induced by cancer cells.

A biodegradable multifunctional nanofibrous membrane for periodontal tissue regeneration

Biomaterial-based membranes represent a promising therapeutic option for periodontal diseases. Although conventional periodontal membranes function greatly in preventing the ingrowth of both fibroblasts and epithelial cells as well as connective tissues, they are not capable of promoting periodontal tissue regeneration. Here, we report a multifunctional periodontal membrane prepared by electrospinning biodegradable polymers with magnesium oxide nanoparticles (nMgO). nMgO is a light metal-based nanoparticle with high antibacterial capacity and can be fully resorbed in the body. Our results showed that incorporating nMgO into poly(L-lactic acid) (PLA)/gelatin significantly improved the overall properties of membranes, including elevated tensile strength to maintain structural stability and adjusted degradation rate to fit the time window of periodontal regeneration. Acidic degradation products of PLA were neutralized by alkaline ions from nMgO hydrolysis, ameliorating pH microenvironment beneficial for cell proliferation. In vitro studies demonstrated considerable antibacterial and osteogenic properties of nMgO-incorporated membranes that are highly valuable for periodontal regeneration. Further investigations in a rat periodontal defect model revealed that nMgO-incorporated membranes effectively guided periodontal tissue regeneration. Taken together, our data indicate that nMgO-incorporated membranes might be a promising therapeutic option for periodontal regeneration. STATEMENT OF SIGNIFICANCE: Traditional clinical treatments of periodontal diseases largely focus on the management of the pathologic processes, which cannot effectively regenerate the lost periodontal tissue. GTR, a classic method for periodontal regeneration, has shown promise in clinical practice. However, the current membranes might not fully fulfill the criteria of ideal membranes. Here, we report bioabsorbable nMgO-incorporated nanofibrous membranes prepared by electrospinning to provide an alternative for the clinical practice of GTR. The membranes not only function greatly as physical barriers but also exhibit high antibacterial and osteoinductive properties. We therefore believe that this study will inspire more practice work on the development of effective GTR membranes for periodontal regeneration.

Microfluidic Silk Fibers with Aligned Hierarchical Microstructures

The hierarchical structure of the ECM provides specific niches for tissues to regulate cell behavior, yet the challenge remains to design biomaterial systems for tissue regeneration to recreate such features in vitro. Here, we achieved this goal through the use of aligned hierarchical structures of native silk fibers, generated through the integration of "bottom-up" and "top-down" strategies to generate regenerated silk fibers with aligned nano- to micro-hierarchical structures. To achieve these designs, we assembled and dispersed silk nanofibers (SNF) in formic acid and spun them into fibers using bioinspired microfluidic chips with a geometry mimicking the native silk gland. The fibers generated using this device exhibited aligned hierarchical structure with fiber mechanical properties superior to fibers derived from more traditional spinning approaches with regenerated silk solutions. Besides the improved mechanical properties, Raman spectroscopic results indicated similarly aligned structures to native fibers and active control of cell proliferation, migration, and aggregate orientation. The results indicate the feasibility of developing bioactive silk fiber materials with hierarchical structures to facilitate utility in a range of cell and tissue regeneration scenarios.

Microcarriers for Upscaling Cultured Meat Production

Due to the considerable environmental impact and the controversial animal welfare associated with industrial meat production, combined with the ever-increasing global population and demand for meat products, sustainable production alternatives are indispensable. In 2013, the world's first laboratory grown hamburger made from cultured muscle cells was developed. However, coming at a price of $300.000, and being produced manually, substantial effort is still required to reach sustainable large-scale production. One of the main challenges is scalability. Microcarriers (MCs), offering a large surface/volume ratio, are the most promising candidates for upscaling muscle cell culture. However, although many MCs have been developed for cell lines and stem cells typically used in the medical field, none have been specifically developed for muscle stem cells and meat production. This paper aims to discuss the MCs' design criteria for skeletal muscle cell proliferation and subsequently for meat production based on three scenarios: (1) MCs are serving only as a temporary substrate for cell attachment and proliferation and therefore they need to be separated from the cells at some stage of the bioprocess, (2) MCs serve as a temporary substrate for cell proliferation but are degraded or dissolved during the bioprocess, and (3) MCs are embedded in the final product and therefore need to be edible. The particularities of each of these three bioprocesses will be discussed from the perspective of MCs as well as the feasibility of a one-step bioprocess. Each scenario presents advantages and drawbacks, which are discussed in detail, nevertheless the third scenario appears to be the most promising one for a production process. Indeed, using an edible material can limit or completely eliminate dissociation/degradation/separation steps and even promote organoleptic qualities when embedded in the final product. Edible microcarriers could also be used as a temporary substrate similarly to scenarios 1 and 2, which would limit the risk of non-edible residues.

Performance of PEGylated chitosan and poly (L-lactic acid-co-ε-caprolactone) bilayer vascular grafts in a canine femoral artery model

The fabrication of a functional small-diameter vascular graft with good biocompatibility, in particular hemocompatibility, has become an urgent clinical necessity. We fabricated a native bilayer, small-diameter vascular graft using PEGylated chitosan (PEG-CS) and poly (L-lactic acid-co-ε-caprolactone; PLCL). To stabilize the inner layer, a PEG-CS blend with PLCL at ratio of 1:6 was casted on a round metal bar by a drip feed, and the outer layer, a PLCL blend with water-soluble PEG that acted as a sacrificial part to enhance pore size, was fabricated by electrospinning. The results showed excellent hemocompatibility and strong mechanical properties. In vitro, the degradation of the graft was evaluated by measuring the graft structure, mass loss rate, and changes in molecular weight. The results indicated that the graft had adequate support for the regeneration of blood vessels before collapse. An in vivo study was performed in a canine femoral artery model for up to 24 weeks, which demonstrated that the PEGylated bilayer grafts possessed excellent structural integrity, high compatibility with blood, good endothelial cell (EC) and smooth muscle cell (SMC) growth, and high expression levels of angiogenesis-related proteins, features that are highly similar to autologous blood vessels. Moreover, the results showed almost negligible calcification within 24 weeks. These findings confirm that the bilayer graft mimics native cells, thereby effectively improving vascular remodeling.

Collagen-functionalized electrospun smooth and porous polymeric scaffolds for the development of human skin-equivalent

Electrospun polymer fibers have garnered substantial importance in regenerative medicine owing to their intrinsic 3D topography, extracellular matrix microenvironment, biochemical flexibility, and mechanical support. In particular, a material's nano-topography can have a significant effect on cellular responses, including adhesion, proliferation, differentiation, and migration. In this study, poly(l-lactic acid) (PLLA), a biodegradable polymer with excellent biocompatibility was electrospun into fibers with either smooth or porous topologies. The scaffolds were further modified and biofunctionalized with 0.01% and 0.1% collagen to enhance bioactivity and improve cellular interactions. Human keratinocytes (HaCaTs) and fibroblasts (human foreskin fibroblasts-HFF) were cultured on the scaffolds using a modified co-culture technique, where keratinocytes were grown on the dorsal plane for 5 days, followed by flipping, seeding with fibroblasts on the ventral plane and culturing for a further 5 days. Following this, cellular adhesion of the skin cells on both the unmodified and collagen-modified scaffolds (smooth and porous) was performed using scanning electron microscopy (SEM) and immunofluorescence. Distinct outcomes were observed with the unmodified smooth scaffolds showing superior cell adhesion than the porous scaffolds. Modification of the porous and smooth scaffolds with 0.1% collagen enhanced the adhesion and migration of both keratinocytes and fibroblasts to these scaffolds. Further, the collagen-modified scaffolds (both porous and smooth) produced confluent and uniform epidermal sheets of keratinocytes on one plane with healthy fibroblasts populated within the scaffolds. Thus, presenting a vast potential to serve as a self-organized skin substitute this may be a promising biomaterial for development as a dressing for patients suffering from wounds.

Collagen-functionalized electrospun smooth and porous poly(l-lactide) scaffolds supporting keratinocytes and fibroblasts as a potential model to serve as self-organized skin substitute.

The effect of Substance P/Heparin conjugated PLCL polymer coating of bioinert ePTFE vascular grafts on the recruitment of both ECs and SMCs for accelerated regeneration

Artificial vascular grafts consisting of ePTFE have been mainly used in clinics for the treatment of cardiovascular disease. However, artificial grafts can become clogged after a long time due to thrombosis, as graft maturation by endothelialization is limited. The strategy introduced in this study is to induce graft remodeling through interaction between the bioinert graft and the body. The Substance P (SP) and heparin were covalently conjugated with PLCL, an elastic biocompatible copolymer and the Substance P-conjugated PLCL (SP-PLCL) and/or heparin-conjugated PLCL (Hep-PLCL) were vacuum-coated onto ePTFE vascular grafts. To assess the effectiveness of the coating, coated samples were evaluated by implanting them subcutaneously into SD-Rats. Coatings allow grafts to be remodeled by creating a microenvironment where cells can grow by infiltrating into the grafts while also greatly enhancing angiogenesis. In particular, a double coating of Hep-PLCL and SP-PLCL (Hep/SP-PLCL) at four weeks showed markedly improved vascular remodeling through the recruitment of mesenchymal stem cells (MSCs), vascular cells (ECs, SMCs) and M2 macrophages. Based on these results, it is expected that when the Hep/SP-PLCL-coated ePTFE vascular grafts are implanted in situ, long-term patency will be assured due to the appropriate formation of an endothelial layer and smooth muscle cells in the grafts like native vessels.