PCL-gelatin composite nanofibers electrospun using diluted acetic acid-ethyl acetate solvent system for stem cell-based bone tissue engineering

Electrohydrodynamic Direct-Writing Micro/Nanofibrous Architectures: Principle, Materials, and Biomedical Applications

Electrohydrodynamic (EHD) direct-writing has recently gained attention as a highly promising additive manufacturing strategy for fabricating intricate micro/nanoscale architectures. This technique is particularly well-suited for mimicking the extracellular matrix (ECM) present in biological tissue, which serves a vital function in facilitating cell colonization, migration, and growth. The integration of EHD direct-writing with other techniques has been employed to enhance the biological performance of scaffolds, and significant advancements have been made in the development of tailored scaffold architectures and constituents to meet the specific requirements of various biomedical applications. Here, a comprehensive overview of EHD direct-writing is provided, including its underlying principles, demonstrated materials systems, and biomedical applications. A brief chronology of EHD direct-writing is provided, along with an examination of the observed phenomena that occur during the printing process. The impact of biomaterial selection and architectural topographic cues on biological performance is also highlighted. Finally, the major limitations associated with EHD direct-writing are discussed.

A Review of Modified Gelatin: Physicochemical Properties, Modification Methods, and Applications in the Food Field

Gelatin is a significant multifunctional biopolymer that is widely utilized as a component in food, pharmaceuticals, and cosmetics. Numerous functional qualities are displayed by gelatin, such as its exceptional film-forming ability, gelling qualities, foaming and emulsifying qualities, biocompatibility and biodegradable qualities. Due to its unique structural, physicochemical, and biochemical characteristics, which enhance nutritional content and health benefits as well as the stability, consistency, and elasticity of food products, gelatin is utilized extensively in the food business. Additionally, gelatin has demonstrated excellent performance in encapsulating, delivering, and releasing active ingredients. Gelatin's various modifications, such as chemical, enzymatic, and physical processes, were analyzed to assess their impact on gelatin structures and characteristics. Hopefully, gelatin will be more widely used in various applications after modification using suitable methods.

Electrospun Gelatin Scaffolds with Incorporated Antibiotics for Skin Wound Healing

Recent advances in regenerative medicine provide encouraging strategies to produce artificial skin substitutes. Gelatin scaffolds are successfully used as wound-dressing materials due to their superior properties, such as biocompatibility and the ability to mimic the extracellular matrix of the surrounding environment. In this study, five gelatin combination solutions were prepared and successfully electrospun using an electrospinning technique. After careful screening, the optimal concentration of the most promising combination was selected for further investigation. The obtained scaffolds were crosslinked with 25% glutaraldehyde vapor and characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The incorporation of antibiotic agents such as ciprofloxacin hydrochloride and gentamicin sulfate into gelatin membranes improved the already existing antibacterial properties of antibiotic-free gelatin scaffolds against Pseudomonas aeruginosa and Staphylococcus aureus. Also, the outcomes from the in vivo model study revealed that skin regeneration was significantly accelerated with gelatin/ciprofloxacin scaffold treatment. Moreover, the gelatin nanofibers were found to strongly promote the neoangiogenic process in the in vivo chick embryo chorioallantoic membrane assay. Finally, the combination of gelatin's extracellular matrix and antibacterial agents in the scaffold suggests its potential for effective wound-healing treatments, emphasizing the importance of gelatin scaffolds in tissue engineering.

Alginate hydrogel-PCL/gelatin nanofibers composite scaffold containing mesenchymal stem cells-derived exosomes sustain release for regeneration of tympanic membrane perforation

Exosomes are among the most effective therapeutic tools for tissue engineering. This study demonstrates that a 3D composite scaffold containing exosomes can promote regeneration in rat tympanic membrane perforation (TMP). The scaffolds were characterized using scanning electron microscopy (SEM), degradation, PBS adsorption, swelling, porosity, and mechanical properties. To confirm the isolation of exosomes from human adipose-derived mesenchymal stem cells (hAMSCs), western blot, SEM, and dynamic light scattering (DLS) were performed. The Western blot test confirmed the presence of exosomal surface markers CD9, CD81, and CD63. The SEM test revealed that the isolated exosomes had a spherical shape, while the DLS test indicated an average diameter of 82.5 nm for these spherical particles. MTT assays were conducted to optimize the concentration of hAMSCs-exosomes in the hydrogel layer of the composite. Exosomes were extracted on days 3 and 7 from an alginate hydrogel containing 100 and 200 μg/mL of exosomes, with 100 μg/mL identified as the optimal value. The optimized composite scaffold demonstrated improved growth and migration of fibroblast cells. Animal studies showed complete tympanic membrane regeneration (TM) after five days. These results illustrate that a scaffold containing hAMSC-exosomes can serve as an appropriate tissue-engineered scaffold for enhancing TM regeneration.

Influence of Graphene-Based Nanocomposites in Neurogenesis and Neuritogenesis: A Brief Summary

Graphene is a prospective candidate for various biomedical applications, including drug transporters, bioimaging agents, and scaffolds for tissue engineering, thanks to its superior electrical conductivity and biocompatibility. The clinical issue of nerve regeneration and rehabilitation still has a major influence on people's lives. Nanomaterials based on graphene have been exploited extensively to promote nerve cell differentiation and proliferation. Their high electrical conductivity and mechanical robustness make them appropriate for nerve tissue engineering. Combining graphene with other substances, such as biopolymers, may transmit biochemical signals that support brain cell division, proliferation, and regeneration. The utilization of nanocomposites based on graphene in neurogenesis and neuritogenesis is the primary emphasis of this review. Here are some examples of the many synthetic strategies used. For neuritogenesis and neurogenesis, it has also been explored to combine electrical stimulation with graphene-based materials.

Design of Poly(lactic) acid/gelatin core-shell bicomponent systems as a potential wound dressing material

The electrospun core-shell nanofiber has great many advantages such as different types of solvents that can be used for changing flexibility, mechanical properties, or surface chemistry of fiber. Hydrophobic Poly(lactic) acid (PLA) and hydrophilic gelatin (Gel) were electrospun by various preparation conditions to design perfect bicomponent PLA:Gel nanofiber in a core-shell structure. Solvent types, the concentration of polymeric components, flow rate, and voltage of the electrospinning process were changed to optimization of nanofiber. According to the SEM images, the best nanofiber structure without beads was obtained at 0.4 ml/h flow rate of PLA solution and 1.2 ml/h flow rate of Gel solution at 45:55 (w:w %) weight ratio of PLA:Gel in trifluoroethanol solvent with a 10 kV voltage at 10 cm distance to the collector. From the TEM images, the existence of the core-shell structure had been proved which all prepared nanofibers with 2,2,2-Trifluoroethanol solvent. Furthermore, contact angle measurements showed a change in wettability when the Gel amount was increased. Therefore, the mildest synthesis conditions were determined for bicomponent PLA:Gel core-shell nanofibers as a potential wound dressing and dual drug carrier materials.

Development and characterisation of suitably bioengineered microfibrillar matrix-based 3D prostate cancer model forin vitrodrug testing

Bioengineered 3D models that can mimic patient-specific pathologiesin vitroare valuable tools for developing and validating anticancer therapeutics. In this study, microfibrillar matrices with unique structural and functional properties were fabricated as 3D spherical and disc-shaped scaffolds with highly interconnected pores and the potential of the newly developed scaffolds for developing prostate cancer model has been investigated. The newly developed scaffolds showed improved cell retention upon seeding with cancer cells compared to conventional electrospun scaffolds. They facilitated rapid growth and deposition of cancer-specific extracellular matrix through-the-thickness of the scaffold. Compared to the prostate cancer cells grown in 2D culture, the newly developed prostate cancer model showed increased resistance to the chemodrug Docetaxel regardless of the drug concentration or the treatment frequency. A significant reduction in the cell number was observed within one week after the drug treatment in the 2D culture for both PC3 and patient-derived cells. Interestingly, almost 20%-30% of the cancer cells in the newly developed 3D model survived the drug treatment, and the patient-derived cells were more resistant than the tested cell line PC3. The results from this study indicate the potential of the newly developed prostate cancer model forin vitrodrug testing.

Electrospun Poly(L-Lactic Acid)/Gelatin Hybrid Polymer as a Barrier to Periodontal Tissue Regeneration

Poly(L-lactic acid) (PLLA) and PLLA/gelatin polymers were prepared via electrospinning to evaluate the effect of PLLA and gelatin content on the mechanical properties, water uptake capacity (WUC), water contact angle (WCA), degradation rate, cytotoxicity and cell proliferation of membranes. As the PLLA concentration increased from 1 wt% to 3 wt%, the tensile strength increased from 5.8 MPa to 9.1 MPa but decreased to 7.0 MPa with 4 wt% PLLA doping. The WUC decreased rapidly from 594% to 236% as the PLLA content increased from 1 to 4 wt% due to the increased hydrophobicity of PLLA. As the gelatin content was increased to 3 wt% PLLA, the strength, WUC and WCA of the PLLA/gelatin membrane changed from 9.1 ± 0.9 MPa to 13.3 ± 2.3 MPa, from 329% to 1248% and from 127 ± 1.2° to 0°, respectively, with increasing gelatin content from 0 to 40 wt%. However, the failure strain decreased from 3.0 to 0.5. The biodegradability of the PLLA/gelatin blend increased from 3 to 38% as the gelatin content increased to 40 wt%. The viability of L-929 and MG-63 cells in the PLLA/gelatin blend was over 95%, and the excellent cell proliferation and mechanical properties suggested that the tunable PLLA/gelatin barrier membrane was well suited for absorbable periodontal tissue regeneration.

Nanoscale β-TCP-Laden GelMA/PCL Composite Membrane for Guided Bone Regeneration

Major advances in the field of periodontal tissue engineering have favored the fabrication of biodegradable membranes with tunable physical and biological properties for guided bone regeneration (GBR). Herein, we engineered innovative nanoscale beta-tricalcium phosphate (β-TCP)-laden gelatin methacryloyl/polycaprolactone (GelMA/PCL-TCP) photocrosslinkable composite fibrous membranes via electrospinning. Chemo-morphological findings showed that the composite microfibers had a uniform porous network and β-TCP particles successfully integrated within the fibers. Compared with pure PCL and GelMA/PCL, GelMA/PCL-TCP membranes led to increased cell attachment, proliferation, mineralization, and osteogenic gene expression in alveolar bone-derived mesenchymal stem cells (aBMSCs). Moreover, our GelMA/PCL-TCP membrane was able to promote robust bone regeneration in rat calvarial critical-size defects, showing remarkable osteogenesis compared to PCL and GelMA/PCL groups. Altogether, the GelMA/PCL-TCP composite fibrous membrane promoted osteogenic differentiation of aBMSCs in vitro and pronounced bone formation in vivo. Our data confirmed that the electrospun GelMA/PCL-TCP composite has a strong potential as a promising membrane for guided bone regeneration.

Cell-based wound dressing: Bilayered PCL/gelatin nanofibers-alginate/collagen hydrogel scaffold loaded with mesenchymal stem cells

Wound dressing is applied to promote the healing process, wound protection, and additionally regeneration of injured skin. In this study, a bilayer scaffold composed of a hydrogel and nanofibers was fabricated to improve the regeneration of injured skin. To this end, polycaprolactone/gelatin (PCL/Gel) nanofibers were electrospun directly on the prepared collagen/alginate (Col/Alg) hydrogel. The bilayer scaffold was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), mechanical properties, and swelling/degradation time. Cytotoxicity assays were evaluated using MTT assay. Then, the nanofiber and bilayer scaffolds were seeded with Adipose-derived stem cells (ADSCs). ADSCs were isolated from rat adipose tissue and analyzed using flow cytometry, in advance. Full-thickness wounds on the backs of rats were dressed with ADSCs-seeded bilayer scaffolds and nanofibers. Histopathological evaluations were performed after 14 and 21 days using H&E (hematoxylin and eosin) staining. The results indicated that re-epithelialization, angiogenesis, and collagen remodeling were enhanced in ADSCs-seeded bilayer scaffolds and nanofibers in comparison with the control group. In conclusion, the best re-epithelialization, collagen organization, neovascularization, and low presence of inflammation in the wound area were observed in the ADSCs-seeded bilayer scaffolds.

Bioengineered 3D microfibrous-matrix modulates osteopontin release from MSCs and facilitates the expansion of hematopoietic stem cells

The osteopontin released from mesenchymal stem cells (MSC) undergoing lineage differentiation can negatively influence the expansion of hematopoietic stem cells (HSCs) in co-culture systems developed for expanding HSCs. Therefore, minimising the amount of osteopontin in the co-culture system is important for the successful ex vivo expansion of HSCs. Towards this goal, a bioengineered 3D microfibrous-matrix that can maintain MSCs in less osteopontin-releasing conditions has been developed, and its influence on the expansion of HSCs has been studied. The newly developed 3D matrix significantly decreased the release of osteopontin, depending on the MSC culture conditions used during the priming period before HSC seeding. The culture system with the lowest amount of osteopontin facilitated a more than 24-fold increase in HSC number in 1 week time period. Interestingly, the viability of expanded cells and the CD34+ pure population of HSCs were found to be the highest in the low osteopontin-containing system. Therefore, bioengineered microfibrous 3D matrices seeded with MSCs, primed under suitable culture conditions, can be an improved ex vivo expansion system for HSC culture. This article is protected by copyright. All rights reserved.

Control of drug release from cotton fabric by nanofibrous mat

A drug delivery system (DDSs) was developed in the present study based on textile substrates as drug carriers and electrospun nanofibers as a controller of release rate. Three types of drugs consisting of ciprofloxacin (CIP), clotrimazole (CLO), and benzalkonium chloride (BEN) were loaded into the cover glass (CG) and cotton fabrics (CF1 and CF2) separately. Then, the drug-loaded substrates were coated with polycaprolactone (PCL) and polycaprolactone/gelatin (PCL/Gel) nanofibers with various thicknesses. The morphology and hydrophilicity of the electrospun nanofibers and the release profile of drug-loaded samples were investigated. FTIR, XRD, and in vitro biodegradability analysis were analyzed to characterize the drug delivery system. A morphological study of electrospun fibers showed the mean diameter of the PCL and PCL/Gel nanofibers 127 ± 25 and 178 ± 38 nm, respectively. The drug delivery assay revealed that various factors affect the rate of drug releases, such as the type of drug, the type of drug carrier, and the thickness of the covered nanofibers. The study highlights the ability of drugs to load substrates with coated nanofibers as controlled drug delivery systems. In conclusion, it is shown that the obtained samples are excellent candidates for future wound dressing applications.

Gelatin-based electrospun and lyophilized scaffolds with nano scale feature for bone tissue engineering application: review

The rebuilding of the normal functioning of the damaged human body bone tissue is one of the main objectives of bone tissue engineering (BTE). Fabricated scaffolds are mostly treated as artificial supports and as materials for regeneration of neo bone tissues and must closely biomimetic the native extracellular matrix of bone. The materials used for developing scaffolds should be biodegradable, nontoxic, and biocompatible. For the resurrection of bone disorder, specifically natural and synthetic polymers such as chitosan, PCL, gelatin, PGA, PLA, PLGA, etc. meet the requirements for serving their functions as artificial bone substitute materials. Gelatin is one of the potential candidates which could be blended with other polymers or composites to improve its physicochemical, mechanical, and biological performances as a bone graft. Scaffolds are produced by several methods including electrospinning, self-assembly, freeze-drying, phase separation, fiber drawing, template synthesis, etc. Among them, freeze-drying and electrospinning are among the popular, simplest, versatile, and cost-effective techniques. The design and preparation of freeze-dried and electrospun scaffolds are of intense research over the last two decades. Freeze-dried and electrospun scaffolds offer a distinctive architecture at the micro to nano range with desired porosity and pore interconnectivity for selective movement of small biomolecules and play its role as an appropriate matrix very similar to the natural bone extracellular matrix. This review focuses on the properties and functionalization of gelatin-based polymer and its composite in the form of bone scaffolds fabricated primarily using lyophilization and electrospinning technique and their applications in BTE.

Study on the Local Anti-Osteoporosis Effect of Polaprezinc-Loaded Antioxidant Electrospun Membrane

Background

Compared with the healthy condition, osteoporotic bone defects are often accompanied by poor osteogenesis and excessive reactive oxygen species (ROS), which pose serious challenges to bone augmentation and repair by normal resorbable guided bone regeneration (GBR) membrane.

Purpose

Polaprezinc (PZ) was loaded into polycaprolactone/gelatin (PG) hybrid electrospun nanofibers to fabricate a GBR membrane with antioxidant and osteogenesis ability.

Methods

A series of physicochemical characterization were performed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and water contact angle measurement. In addition to membrane degradation and PZ release detection, membranes were tested for cell viability, differentiation, and protein expression in MC3T3-E1 cells by CCK8, alkaline phosphatase activity, mineralization, and Western blotting assays. The membrane osteogenic capacity in cranial bone defects was studied by micro-CT in vivo.

Results

PZ was successfully doped into the PCL/GEL nanofibers to form a hydrophilic GBR membrane. The cumulative release of PZ was closely related to the membrane degradation behavior. PG/0.4%PZ membranes produced the best protective effect on cell proliferation/differentiation under oxidative stress microenvironment; however, the PG/0.8%PZ membrane was cytotoxic. Western blotting demonstrated that the PZ-loaded membrane upregulated the Nrf2/HO-1/SOD1 signaling molecules in a concentration-dependent manner. In addition, micro-CT results showed an abundant formation of new bones in the PG/0.4%PZ group compared to the PG group.

Conclusion

PZ-loaded degradable PG membranes (especially PG/0.4%PZ) have great potential to accelerate bone regeneration in oxidative stress-related diseases.

Electrospun ethyl cellulose/poly caprolactone/gelatin nanofibers: The investigation of mechanical, antioxidant, and antifungal properties for food packaging

The purpose of the present research was to fabricate ethylcellulose (ECL)/polycaprolactone (PCL)/gelatin (GEL) electrospun nanofibers containing Zataria multiflora essential oil (ZEO) and zinc oxide nanoparticle (ZnO) to provide an appropriate substrate for food packaging. The ECL/PCL/GEL was incorporated with ZEO and ZnO at the concentrations of 10, 20, 30 and 50 wt% and 3 wt%, respectively. The results of ECL/PCL/GEL/ZEO/ZnO nanofiber exhibited uniform morphology with a mean diameter ranging from 361.85 ± 18.7 to 467.33 ± 14.50 nm and enhanced thermal stability. The ECL/PCL/GEL/ZEO/ZnO nanofiber had the highest mechanical parameters, such as young's modulus (437.49 ± 18), tensile strength (7.88 ± 0.7), and elongation at break (5.02 ± 0.6) and water contact angle (61.13 ± 0.5), compared with the other nanofibers. The cell viability during 48 and 72 h was obtained to be about more than 80% for all the nanofibers. Additionally, the ECL/PCL/GEL incorporated with 50% ZEO and 3% ZnO displayed the highest antioxidant activity (34.61 ± 1.98%) and antifungal properties against Penicillium notatum and Aspergillus niger. In general, the ECL/PCL/GEL with the weight ratio of 20:70:10 nanofiber incorporated with 30% ZEO and 3% ZnO was obtained to have appropriate mechanical, antioxidant, and antimicrobial properties and thermal stability.

In vitro expansion of human adipose-derived stem cells with delayed senescence through dual stage release of curcumin from mesoporous silica nanoparticles/electrospun nanofibers

Electrospun nanofibers (NFs) were utilized to realize the dual-stage release of curcumin (Curc) to fully support the attachment, viability and proliferation of adipose-derived stem cells (hADSCs) with a delay in cellular senescence. For this purpose, both free Curc and Curc-loaded mesoporous silica nanoparticles (Curc@MSNs) were integrated into the electrospun polycaprolactone/gelatin (PCL/GEL) nanofibrous scaffolds and characterized via FTIR, BET, FE-SEM and TEM. In vitro drug release results demonstrated strong dual stage-discharge of Curc from the Curc/Curc@MSNs-NFs. Because of the combination of initial rapid release and late extended drug release, hADSCs cultured on the Curc/Curc@MSNs-NFs showed the greatest adhesion, metabolic activity and proliferation rate with a fibroblastic phenotype after 28 days of culture. Besides, a significant reduction in senescence-associated lysosomal α-L-fucosidase (SA-α-Fuc) expression and activity was also measured in hADSCs cultured on the Curc/Curc@MSNs-NFs. Moreover, not only the expression of hTERT in mRNA and protein levels was considerably increased in hADSCs seeded on the Curc/Curc@MSNs-NFs, but also the telomerase activity and telomere length were significantly enhanced in the scaffolds compared to the other types of scaffolds and control group. These results uncovered the potential of the two-stage discharge profile of Curc from Curc/Curc@MSNs-NFs to provide the biofunctionality of long-term cultured hADSCs for efficient stem cell-based regenerative therapies.

Intracranially injectable multi-siRNA nanomedicine for the inhibition of glioma stem cells

Background

Nanoparticle siRNA-conjugates are promising clinical therapeutics as indicated by recent US-FDA approval. In glioma stem cells (GSC), multiple stemness associated genes were found aberrant. We report intracranially injectable, multi-gene-targeted siRNA nanoparticle gel (NPG) for the combinatorial silencing of 3 aberrant genes, thus inhibiting the tumorogenic potential of GSCs.

Methods

NPG loaded with siRNAs targeted against FAK, NOTCH-1, and SOX-2 were prepared by the self-assembly of siRNAs with protamine-hyaluronic acid combination. Electron microscopy, DLS, and agarose gel electrophoresis were used for the physicochemical characterization. Cell transfection and gene-silencing efficiency were studied using human mesenchymal stem cells and rat C6 glioma-derived GSCs. Neurosphere inhibition was tested in vitro using GSCs derived from C6 cell line and glioma patient samples. Patient-derived xenograft model and orthotopic rat glioma model were used to test the effect of NPG on in vivo tumorigenicity.

Results

The siRNA nanoparticles with an average size ~ 250 nm and ~ 95% loading efficiency showed cellular uptake in ~95.5% GSCs. Simultaneous gene silencing of FAK, NOTCH-1, and SOX-2 led to the inhibition of neurosphere formation by GSCs, whereas normal stem cells remained unaffected and retained neuronal differentiation capability. GBM PDX models manifested significant impairment in the tumorigenic potential of NPG treated GSCs. Intracranial injection of NPG inhibited tumor growth in orthotopic rat brain tumor model.

Conclusion

Intracranially injectable n-siRNA NPG targeted to multiple stem-cell signaling impairs glioma initiation capabilities of GSCs and inhibited tumor growth in vivo.

3D-printed biphasic scaffolds for the simultaneous regeneration of osteochondral tissues

Osteochondral tissue engineering (OCTE) involves the simulation of highly complex tissues with disparate biomechanical properties. OCTE is regarded as the best option for treating osteochondral defects, most of the drawbacks of current treatment methodologies can be addressed by this method. In recent years, the conventional scaffolds used in cartilage and bone regeneration are gradually being replaced by 3D printed scaffolds (3DP). In the present study, we devised the strategy of 3D printing for fabricating biphasic and integrated scaffolds that are loaded with bioactive factors for enhancing the osteochondral tissue regeneration. Polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA), is used along with bioactive factors (chondroitin sulphate and beta-tricalcium phosphate (βTCP)) for the upper cartilage and lower bone layer respectively. The 3D printed bi-layered scaffolds with varying infill density, to mimic the native tissue, are not previously explored for OCTE. Hence, we tested the simultaneous osteochondrogenic differentiation inducing potential of the aforesaid 3D printed biphasic scaffoldsin vitro, using rabbit adipose derived mesenchymal stem cells (ADMSCs). Further, the biphasic scaffolds were highly cytocompatible, with excellent cell adhesion properties and cellular morphology. Most importantly, these biphasic scaffolds directed the simultaneous differentiation of a single stem cell population in to two cell lineages (simultaneous differentiation of rabbit ADMSCs into chondrocytes and osteoblasts). Further, these scaffolds enhanced the production of ECM and induced robust expression of marker genes that is specific for respective cartilage and bone layers. The 3D printed OCTE scaffold of our study hence can simulate the native osteochondral unit and could be potential futuristic biomimetic scaffold for osteochondral defects. Furtherin vivostudies are warranted.

Development of a decellularized meniscus matrix-based nanofibrous scaffold for meniscus tissue engineering

The meniscus plays a critical role in knee mechanical function but is commonly injured given its central load bearing role. In the adult, meniscus repair is limited, given the low number of endogenous cells, the density of the matrix, and the limited vascularity. Menisci are fibrocartilaginous tissues composed of a micro-/nano- fibrous extracellular matrix (ECM) and a mixture of chondrocyte-like and fibroblast-like cells. Here, we developed a fibrous scaffold system that consists of bioactive components (decellularized meniscus ECM (dME) within a poly(e-caprolactone) material) fashioned into a biomimetic morphology (via electrospinning) to support and enhance meniscus cell function and matrix production. This work supports that the incorporation of dME into synthetic nanofibers increased hydrophilicity of the scaffold, leading to enhanced meniscus cell spreading, proliferation, and fibrochondrogenic gene expression. This work identifies a new biomimetic scaffold for therapeutic strategies to substitute or replace injured meniscus tissue. STATEMENT OF SIGNIFICANCE: In this study, we show that a scaffold electrospun from a combination of synthetic materials and bovine decellularized meniscus ECM provides appropriate signals and a suitable template for meniscus fibrochondrocyte spreading, proliferation, and secretion of collagen and proteoglycans. Material characterization and in vitro cell studies support that this new bioactive material is susceptible to enzymatic digestion and supports meniscus-like tissue formation.

Poly (ε-caprolactone)-based electrospun nano-featured substrate for tissue engineering applications: a review

The restoration of normal functioning of damaged body tissues is one of the major objectives of tissue engineering. Scaffolds are generally used as artificial supports and as substrates for regenerating new tissues and should closely mimic natural extracellular matrix (ECM). The materials used for fabricating scaffolds must be biocompatible, non-cytotoxic and bioabsorbable/biodegradable. For this application, specifically biopolymers such as PLA, PGA, PTMC, PCL etc. satisfying the above criteria are promising materials. Poly(ε-caprolactone) (PCL) is one such potential candidate which can be blended with other materials forming blends, copolymers and composites with the essential physiochemical and mechanical properties as per the requirement. Nanofibrous scaffolds are fabricated by various techniques such as template synthesis, fiber drawing, phase separation, self-assembly, electrospinning etc. Among which electrospinning is the most popular and versatile technique. It is a clean, simple, tunable and viable technique for fabrication of polymer-based nanofibrous scaffolds. The design and fabrication of electrospun nanofibrous scaffolds are of intense research interest over the recent years. These scaffolds offer a unique architecture at nano-scale with desired porosity for selective movement of small molecules and form a suitable three-dimensional matrix similar to ECM. This review focuses on PCL synthesis, modifications, properties and scaffold fabrication techniques aiming at the targeted tissue engineering applications.

Prolonged proliferation and delayed senescence of the adipose-derived stem cells grown on the electrospun composite nanofiber co-encapsulated with TiO2 nanoparticles and metformin-loaded mesoporous silica nanoparticles

This study was aimed to investigate the effects of the Poly-ε-Caprolactone/Gelatin nanofibers (PCL/GEL NFs) co-encapsulated with TiO₂ nanoparticles (nTiO₂) and metformin-loaded mesoporous silica nanoparticles (MET@MSNs) on prolonging the in vitro expansion of human adipose-derived stem cells (hADSCs) without inducing cellular senescence and aging. FTIR, BET, FE-SEM, and TEM were applied to characterize the fabricated MET@MSNs and electrospun composite NFs. The presence of inorganic particles, nTiO₂ and MSNs, in the scaffolds improved their mechanical properties and led to a more sustained release of MET with almost the lack of the initial burst release from nTiO₂/MET@MSNs-loaded NFs. The enhanced adhesion, metabolic activity, and proliferation rate of the hADSCs grown on nTiO₂/MET@MSNs-loaded NFs were demonstrated via FE-SEM images, MTT test and PicoGreen assay, respectively, over 28 days of culture. Furthermore, the irregular nanofibrillar structures and the impact of sustained release of MET led to a significant upregulation in the mRNA levels of autophagy (Atg-5, Atg-7, Atg-12, and Beclin-1) and stemness (Nanog3, Sox-2, and Oct-4) markers as well as a considerable down-regulation of p16^INK4A senescence marker. Further, the upregulation of hTERT, enhanced activity of telomerase, and increased telomere length were more pronounced in the hADSCs cultured on nTiO₂/MET@MSNs-loaded NFs as compared to other types of NFs. Overall, our findings demonstrated the potential of the fabricated nanocomposite platform for counteracting cellular senescence and achieving sufficient quantities of fresh hADSCs with preserved stemness for various stem cell-based regenerative medicine purposes.

In-vitro Characterization of a Hernia Mesh Featuring a Nanostructured Coating

Abdominal hernia repair is a frequently performed surgical procedure worldwide. Currently, the use of polypropylene (PP) surgical meshes for the repair of abdominal hernias constitutes the primary surgical approach, being widely accepted as superior to primary suture repair. Surgical meshes act as a reinforcement for the weakened or damaged tissues and support tissue restoration. However, implanted meshes could suffer from poor integration with the surrounding tissues. In this context, the present study describes the preliminary evaluation of a PCL-Gel-based nanofibrous coating as an element to develop a multicomponent hernia mesh device (meshPCL-Gel) that could overcome this limitation thanks to the presence of a nanostructured biomimetic substrate for enhanced cell attachment and new tissue formation. Through the electrospinning technique, a commercial PP hernia mesh was coated with a nanofibrous membrane from a polycaprolactone (PCL) and gelatin (Gel) blend (PCL-Gel). Resulting PCL-Gel nanofibers were homogeneous and defect-free, with an average diameter of 0.15 ± 0.04 μm. The presence of Gel decreased PCL hydrophobicity, so that membranes average water contact angle dropped from 138.9 ± 1.1° (PCL) to 99.9 ± 21.6°, while it slightly influenced mechanical properties, which remained comparable to those of PCL (E = 15.7 ± 2.7 MPa, σ R = 7.7 ± 0.6 ε R = 118.8 ± 13.2%). Hydrolytic and enzymatic degradation was conducted on PCL-Gel up to 28 days, with maximum weight losses around 20 and 40%, respectively. The meshPCL-Gel device was obtained with few simple steps, with no influences on the original mechanical properties of the bare mesh, and good stability under physiological conditions. The biocompatibility of meshPCL-Gel was assessed by culturing BJ human fibroblasts on the device, up to 7 days. After 24 h, cells adhered to the nanofibrous substrate, and after 72 h their metabolic activity was about 70% with respect to control cells. The absence of detectable lactate dehydrogenase in the culture medium indicated that no necrosis induction occurred. Hence, the developed nanostructured coating provided the meshPCL-Gel device with chemical and topographical cues similar to the native extracellular matrix ones, that could be exploited for enhancing the biological response and, consequently, mesh integration, in abdominal wall hernia repair.

Regulated Surface Morphology of Polyaniline/Polylactic Acid Composite Nanofibers via Various Inorganic Acids Doping for Enhancing Biocompatibility in Tissue Engineering

Conductive and degradable nanofibrous scaffolds have great potential in promoting cell growth, proliferation, and differentiation under an external electric field. Although the issue of inferior electrical conductivity in body fluids still exists, polyaniline (PANI)-based degradable nanofibers can promote cell adhesion, growth, and proliferation. To investigate whether the effect is caused by the PANI morphology, we selected three inorganic acids as dopants in the process of PANI in situ oxidative polymerization: hydrochloric acid, sulfuric acid, and perchloric acid. The obtained polyaniline/polylactic acid (PANI/PLA) composite nanofibers were characterized via SEM, FTIR, and XPS analysis, and we confirmed that the PLA nanofibers were successfully coated by PANI without any change to the porous structure of the PLA nanofibers. The in vitro mechanical properties and degradability indicated that the oxidation of acid dopants should be considered and that it was likely to have a higher oxidation degradation effect on PLA nanofibers. The contact angle test demonstrated that PANI/PLA composite nanofibers with different surface morphologies have good wettability, implying that they meet the requirements of bone tissue engineering scaffolds. The surface roughness and cell viability demonstrated that different PANI morphologies on the surface can promote cell proliferation. The higher the surface roughness of the PANI, the better the biocompatibility. Consequently, the regulated surface morphology of PANI/PLA composite nanofibers via different acids doping has positive effect on biocompatibility in tissue engineering.

Electrospun Bioabsorbable Fibers Containing S-Nitrosoglutathione for Tissue Engineering Applications

Blended and coaxial fibers comprising polycaprolactone and gelatin, containing the endogenous nitric oxide (NO) donor S-nitrosoglutathione (GSNO), were electrospun. Both types of fibers had their NO release profiles tested under physiological conditions to examine their potential applications as biomedical scaffolds. The coaxial fibers exhibited a prolonged and consistent release of NO over the course of 4 d from the core-encapsulated GSNO, while the blended fibers had a large initial release and leaching of GSNO that was exhausted over a shorter period of time. Bacterial testing of both fiber scaffolds was conducted over a 24 h period against Staphylococcus aureus (S. aureus) and demonstrated a 3-log reduction in bacterial viability. In addition, no cytotoxic response was reported when the material was tested on mouse fibroblast cells in vitro. These fibrous matrices were also shown to support cell growth, attachment, and overall activity of fibroblasts when exposed to NO, especially when GSNO was encapsulated within coaxial fibers. From an application point of view, these NO-releasing fibers offer great potential in tissue engineering and biomedical applications because of the crucial role of NO in regulating a variety of biological processes in humans such as angiogenesis, tissue remodeling, and eliminating foreign pathogens.

Dual drug-delivering polycaprolactone-collagen scaffold to induce early osteogenic differentiation and coupled angiogenesis

Bone regeneration is a multi-step, overlapping process, in which angiogenesis and osteogenesis are the key players. Several attempts have been made to promote angiogenesis-coupled osteogenesis using scaffolding technology. However, the recreation of functional vasculature during bone regeneration is an unparalleled challenge. In this study, a dual drug-delivering polycaprolactone-collagen fibrous scaffold is reported to promote early osteogenesis and angiogenesis. Simvastatin as a pro-angiogenic and dexamethasone as an osteoinductive drug were encapsulated to functionalize the electrospun fibers. The optically transparent fibrous mat represented the sustained and sequential release of drugs for 28 days. The fibrous mesh increased cell proliferation and enhanced the osteogenic differentiation up to 21 days. The alkaline phosphatase activity and mineral deposition were comparatively higher on dual drug-releasing fibers when compared to control fibers. The dual drug-releasing osteoconductive fibers demonstrated osteogenesis as early as 7 days with a 3.7 and 1.5 fold increase in the expression of osteogenic differentiation markers (RUNX2 and osteocalcin), respectively. In vitro angiogenesis using primary human umbilical vein endothelial cells (pHUVECs) showed no significant difference in cell proliferation among control fibers and dual drug-releasing fibers. However, the angioinductive nature of simvastatin released from the fibers demonstrated tube formation and 2 fold higher angiogenic score. The mRNA and protein expression study of angiogenic markers (VEGFR2 and eNOS) by polymerase chain reaction and western blotting depicted the angioinducing potential of dual drug-releasing fibers. VEGFR2 and eNOS mRNA expressions increased by 1.1 and 1.6 fold, respectively, whereas their protein expression increased by 3.2 and 1.7 fold, respectively. The overall results demonstrate the synergistic effect of osteoconductive substrate and osteoinductive dual drugs to promote early osteogenesis, and release of the pro-angiogenic drug promotes angiogenesis.

Current challenges and future trends in manufacturing small diameter artificial vascular grafts in bioreactors

Cardiovascular diseases are a leading cause of death. Vascular surgery is mainly used to solve this problem. However, the generation of a functional and suitable substitute for small diameter (< 6 mm) displacement is challengeable. Moreover, synthetic prostheses, made of polyethylene terephthalate and extended polytetrafluoroethylene show have shown insufficient performance. Therefore, the challenges dominating the use of autografts have prevented their efficient use. Tissue engineering is highlighted in regenerative medicine perhaps in aiming to address the issue of end-stage organ failure. While organs and complex tissues require the vascular supply to support the graft survival and render the bioartificial organ role, vascular tissue engineering has shown to be a hopeful method for cell implantation by the production of tissues in vitro. Bioreactors are a salient point in vascular tissue engineering due to the capability for reproducible and controlled variations showing a new horizon in blood vessel substitution. This review strives to display the overview of current concepts in the development of small-diameter by using bioreactors. In this work, we show a critical look at different factors for developing small-diameter and give suggestions for future studies.

MLR and ANN Approaches for Prediction of Synthetic/Natural Nanofibers Diameter in the Environmental and Medical Applications

Fiber diameter plays an important role in the properties of electrospinning of nanofibers. However, one major problem is the lack of a comprehensive method that can link processing parameters to nanofibers' diameter. The objective of this study is to develope an artificial neural network (ANN) modeling and multiple regression (MLR) analysis approaches to predict the diameter of nanofibers. Processing parameters, including weight ratio, voltage, injection rate, and distance, were considered as independent variables and the nanofiber diameter as the dependent variable of the ANN model. The results of ANN modeling, especially its high accuracy (R2 = 0.959) in comparison with MLR results (R2 = 0.564), introduced the prediction the diameter of nanofibers model (PDNFM) as a comparative model for predicting the diameter of poly (3-caprolactone) (PCL)/gelatin (Gt) nanofibers. According to the result of sensitivity analysis of the model, the values of weight ratio, distance, injection rate, and voltage, respectively, were identified as the most significant parameters which influence PDNFM.

Bioactive polymeric scaffolds for osteogenic repair and bone regenerative medicine

The loss of bone tissue is a striking challenge in orthopedic surgery. Tissue engineering using various advanced biofunctional materials is considered a promising approach for the regeneration and substitution of impaired bone tissues. Recently, polymeric supportive scaffolds and biomaterials have been used to rationally promote the generation of new bone tissues. To restore the bone tissue in this context, biofunctional polymeric materials with significant mechanical robustness together with embedded materials can act as a supportive matrix for cellular proliferation, adhesion, and osteogenic differentiation. The osteogenic regeneration to replace defective tissues demands greater calcium deposits, high alkaline phosphatase activity, and profound upregulation of osteocalcin as a late osteogenic marker. Ideally, the bioactive polymeric scaffolds (BPSs) utilized for bone tissue engineering should impose no detrimental impacts and function as a carrier for the controlled delivery and release of the loaded molecules necessary for the bone tissue regeneration. In this review, we provide comprehensive insights into different synthetic and natural polymers used for the regeneration of bone tissue and discuss various technologies applied for the engineering of BPSs and their physicomechanical properties and biological effects.

The physical microenvironment of hematopoietic stem cells and its emerging roles in engineering applications

Stem cells are considered the fundamental underpinnings of tissue biology. The stem cell microenvironment provides factors and elements that play significant roles in controlling the cell fate direction. The bone marrow is an important environment for functional hematopoietic stem cells in adults. Remarkable progress has been achieved in the area of hematopoietic stem cell fate modulation based on the recognition of biochemical factors provided by bone marrow niches. In this review, we focus on emerging evidence that hematopoietic stem cell fate is altered in response to a variety of microenvironmental physical cues, such as geometric properties, matrix stiffness, and mechanical forces. Based on knowledge of these biophysical cues, recent developments in harnessing hematopoietic stem cell niches ex vivo are also discussed. A comprehensive understanding of cell microenvironments helps provide mechanistic insights into pathophysiological mechanisms and underlies biomaterial-based hematopoietic stem cell engineering.

Niobium pentoxide and hydroxyapatite particle loaded electrospun polycaprolactone/gelatin membranes for bone tissue engineering

Effective methods of accelerating the bone regeneration healing process are in demand for a number of bone-related diseases and trauma. This work developed scaffolds with improved properties for bone tissue engineering by electrospinning composite polycaprolactone-gelatin-hydroxyapatite-niobium pentoxide (PGHANb) membranes. Composite membranes, with average fiber diameters ranging from 123 to 156 nm, were produced by adding hydroxyapatite (HA) and varying concentrations of niobium pentoxide (Nb₂O₅) particles (0, 3, 7, and 10 wt%) to a polycaprolactone (PCL) and gelatin (GL) matrix prior to electrospinning. The morphology, mechanical, chemical and biological properties of resultant membranes were evaluated. Bioactivity was assessed using simulated body fluid (SBF) and it confirmed that the presence of particles induced the formation of hydroxyapatite crystals on the surface of the membranes. Samples were hydrophilic and cell metabolism results showed that the niobium-containing membranes were non-toxic while improving cell proliferation and differentiation compared to controls. This study demonstrated that electrospun membranes containing HA and Nb₂O₅ particles have potential to promote cell adhesion and proliferation while exhibiting bioactive properties. PGHANb membranes are promising candidates for bone tissue engineering applications.

Advancements and frontiers in nano-based 3D and 4D scaffolds for bone and cartilage tissue engineering

Given the enormous increase in the risks of bone and cartilage defects with the rise in the aging population, the current treatments available are insufficient for handling this burden, and the supply of donor organs for transplantation is limited. Therefore, tissue engineering is a promising approach for treating such defects. Advances in materials research and high-tech optimized fabrication of scaffolds have increased the efficiency of tissue engineering. Electrospun nanofibrous scaffolds and hydrogel scaffolds mimic the native extracellular matrix of bone, providing a support for bone and cartilage tissue engineering by increasing cell viability, adhesion, propagation, and homing, and osteogenic isolation and differentiation, vascularization, host integration, and load bearing. The use of these scaffolds with advanced three- and four-dimensional printing technologies has enabled customized bone grafting. In this review, we discuss the different approaches used for cartilage and bone tissue engineering.

Smart electrospun nanofibers containing PCL/gelatin/graphene oxide for application in nerve tissue engineering

Currently graphene-doped electrospun scaffolds have been a matter of great interest to be exploited in biomedical fields such as tissue engineering and drug delivery applications. The main objective of this paper is to evaluate the effect of graphene on biological properties of PCL/gelatin nanofibrous mats. SEM analysis was conducted to investigate the morphology of the electrospun nanofibers. The in-vitro cellular proliferation of PC12 cells on nanofibrous web was also investigated. Electrospun PCL/gelatin/graphene nanofibrous mats exhibited 99% antibacterial properties against gram-positive and gram-negative bacteria. Drug release studies indicated that the π-π stacking interaction between TCH and graphene has led to the far better controlled release of TCH from electrospun PCL/gelatin/graphene compared to PCL/gelatin nanofibrous scaffolds. These superior properties along with an improvement in hydrophilicity and biodegradation features has made the nanofibers a promising candidate to be used as electrically conductive scaffolds in neural tissue engineering as well as controlled drug delivery.

Electrospun Nanometer to Micrometer Scale Biomimetic Synthetic Membrane Scaffolds in Drug Delivery and Tissue Engineering: A Review

The scaffold technology research utilizes biomimicry to produce efficient scaffolds that mimic the natural cell growth environment including the basement membrane for tissue engineering. Because the natural basement membrane is composed of fibrillar protein networks of nanoscale diameter, the scaffold produced should efficiently mimic the nanoscale topography at a low production cost. Electrospinning is a technique that can achieve that. This review discusses the physical and chemical characteristics of the basement membrane and its significance on cell growth and overall focuses on nanoscale biomimetic synthetic membrane scaffolds primarily generated using electrospinning and their application in drug delivery and tissue engineering.