Incorporating platelet-rich plasma into coaxial electrospun nanofibers for bone tissue engineering

Enhanced wound regeneration by PGS/PLA fiber dressing containing platelet-rich plasma: an in vitro study

Novel wound dressings with therapeutic effects are being continually designed to improve the wound healing process. In this study, the structural, chemical, physical, and biological properties of an electrospun poly glycerol sebacate/poly lactide acid/platelet-rich plasma (PGS/PLA-PRP) nanofibers were evaluated to determine its impacts on in vitro wound healing. Results revealed desirable cell viability in the Fibroblast (L929) and macrophage (RAW-264.7) cell lines as well as human umbilical vein endothelial cells (HUVEC). Cell migration was evident in the scratch assay (L929 cell line) so that it promoted scratch contraction to accelerate in vitro wound healing. Moreover, addition of PRP to the fiber structure led to enhanced collagen deposition (~ 2 times) in comparison with PGS/PLA scaffolds. While by addition PRP to PGS/PLA fibers not only decreased the expression levels of pro-inflammatory cytokines (IL-6 and TNF-α) in RAW-264.7 cells but also led to significantly increased levels of cytokine (IL-10) and the growth factor (TGF-β), which are related to the anti-inflammatory phase (M2 phenotype). Finally, PGS/PLA-PRP was found to induce a significant level of angiogenesis by forming branching points, loops, and tubes. Based on the results obtained, the PGS/PLA-PRP dressing developed might be a promising evolution in skin tissue engineering ensuring improved wound healing and tissue regeneration.

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

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

Coaxial electrospun PGS/PCL and PGS/PGS-PCL nanofibrous membrane containing platelet-rich plasma for skin tissue engineering

Wound healing will be enhanced using structures with therapeutic effects. This study fabricated a novel nanofibrous scaffold for skin tissue regeneration using a coaxial structure polyglycerol sebacate (PGS)/platelet-rich plasma (PRP) was embedded in the core and two different compositions were selected for the shell; in one group, polycaprolactone (PCL), and in the other group, PGS/PCL blend was used. The physical, mechanical behavior, drug delivery patterns, and cell response of scaffolds were evaluated. Results revealed that by adding PRP to the core and PGS to the shell, fiber diameters decreased to 260.8 ± 31.3 nm. It also decreased the water contact angle from 66° to 32°, that is ideal candidate for cell attachment. The drug release showed a burst release pattern in the first 30 min, followed by a continuous and slow release during the first day. Adding PGS to the shell decreased the elastic modulus, and its value reached about 500 kPa, which is near the skin elastic modulus and will lead to greater mechanical compatibility for cell proliferation. Particularly, the addition of PRP to the fiber structure enhanced the cell viability and cell adhesion with a suitable morphology. Based on the results, nanofibrous PGS-PRP/PGS-PCL dressing can enhance skin tissue regeneration.

Cord blood platelet rich plasma (PRP) as a potential alternative to autologous PRP for allogenic preparation and regenerative applications

As an abundant supplier of growth factors, chemokines and other bioactive molecules, platelet rich plasma (PRP) become a leading therapy for tissue regeneration. The PRP therapy is an inexpensive and feasible source of growth factor compared to commercial products however, the better source of platelets is the major challenge. Many researchers are skeptical about cord blood as an alternative source for the allogenic preparation of PRP. In the present study, we have compared adult peripheral and cord blood PRP for their regenerative capacity and immuno-modulatory nature. ELISA data indicates that the cord PRP contained a considerably higher amount of growth factors compared to adult PRP. In-vitro results indicate a significant increase in cell proliferation and migration with cord PRP treatment. The immunomodulatory evaluation shows cord blood PRP has better potential in switching activated macrophages to anti-inflammatory markers when compared with adult PRP, as well as the cytokines production indicates a significant reduction in the release of IFN-γ in cord PRP treatment. The study shows the beneficial effects of using cord blood PRP over adult PRP however, future studies are required to validate cord blood PRP as a permanent source for regenerative therapy.

Bone-Regeneration Therapy Using Biodegradable Scaffolds: Calcium Phosphate Bioceramics and Biodegradable Polymers

Calcium phosphate-based synthetic bone is broadly used for the clinical treatment of bone defects caused by trauma and bone tumors. Synthetic bone is easy to use; however, its effects depend on the size and location of the bone defect. Many alternative treatment options are available, such as joint arthroplasty, autologous bone grafting, and allogeneic bone grafting. Although various biodegradable polymers are also being developed as synthetic bone material in scaffolds for regenerative medicine, the clinical application of commercial synthetic bone products with comparable performance to that of calcium phosphate bioceramics have yet to be realized. This review discusses the status quo of bone-regeneration therapy using artificial bone composed of calcium phosphate bioceramics such as β-tricalcium phosphate (βTCP), carbonate apatite, and hydroxyapatite (HA), in addition to the recent use of calcium phosphate bioceramics, biodegradable polymers, and their composites. New research has introduced potential materials such as octacalcium phosphate (OCP), biologically derived polymers, and synthetic biodegradable polymers. The performance of artificial bone is intricately related to conditions such as the intrinsic material, degradability, composite materials, manufacturing method, structure, and signaling molecules such as growth factors and cells. The development of new scaffold materials may offer more efficient bone regeneration.

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Bioactive Scaffolds as a Promising Alternative for Enhancing Critical-Size Bone Defect Regeneration in the Craniomaxillofacial Region

Reconstruction of critical-size bone defects (CSDs) in the craniomaxillofacial (CMF) region remains challenging. Scaffold-based bone-engineered constructs have been proposed as an alternative to the classical treatments made with autografts and allografts. Scaffolds, a key component of engineered constructs, have been traditionally viewed as biologically passive temporary replacements of deficient bone lacking intrinsic cues to promote osteogenesis. Nowadays, scaffolds are functionalized, giving rise to bioactive scaffolds promoting bone regeneration more effectively than conventional counterparts. This review focuses on the three approaches most used to bioactivate scaffolds: (1) conferring microarchitectural designs or surface nanotopography; (2) loading bioactive molecules; and (3) seeding stem cells on scaffolds, providing relevant examples of in vivo (preclinical and clinical) studies where these methods are employed to enhance CSDs healing in the CMF region. From these, adding bioactive molecules (specifically bone morphogenetic proteins or BMPs) to scaffolds has been the most explored to bioactivate scaffolds. Nevertheless, the downsides of grafting BMP-loaded scaffolds in patients have limited its successful translation into clinics. Despite these drawbacks, scaffolds containing safer, cheaper, and more effective bioactive molecules, combined with stem cells and topographical cues, remain a promising alternative for clinical use to treat CSDs in the CMF complex replacing autografts and allografts.

Electrosprayed Stearic-Acid-Coated Ethylcellulose Microparticles for an Improved Sustained Release of Anticancer Drug

Sustained release is highly desired for "efficacious, safe and convenient" drug delivery, particularly for those anticancer drug molecules with toxicity. In this study, a modified coaxial electrospraying process was developed to coat a hydrophobic lipid, i.e., stearic acid (SA), on composites composed of the anticancer drug tamoxifen citrate (TC) and insoluble polymeric matrix ethylcellulose (EC). Compared with the electrosprayed TC-EC composite microparticles M1, the electrosprayed SA-coated hybrid microparticles M2 were able to provide an improved TC sustained-release profile. The 30% and 90% loaded drug sustained-release time periods were extended to 3.21 h and 19.43 h for M2, respectively, which were significantly longer than those provided by M1 (0.88 h and 9.98 h, respectively). The morphology, inner structure, physical state, and compatibility of the components of the particles M1 and M2 were disclosed through SEM, TEM, XRD, and FTIR. Based on the analyses, the drug sustained-release mechanism of multiple factors co-acting for microparticles M2 is suggested, which include the reasonable selections and organizations of lipid and polymeric excipient, the blank SA shell drug loading, the regularly round shape, and also the high density. The reported protocols pioneered a brand-new manner for developing sustained drug delivery hybrids through a combination of insoluble cellulose gels and lipid using modified coaxial electrospraying.

Chitosan, polyethylene oxide/polycaprolactone electrospun core/shell nanofibrous mat containing rosuvastatin as a novel drug delivery system for enhancing human mesenchymal stem cell osteogenesis

Introduction: Due to the potential positive effects of rosuvastatin (RSV) on human mesenchymal stem cells (MSCs) osteogenesis and new bone regeneration, it is crucial to develop a suitable carrier that can effectively control the release profile of RSV. The primary objective of this study was to introduce a novel drug delivery system based on core/shell nanofibrous structures, enabling a sustained release of RSV. Methods: To achieve this, coaxial electrospinning was employed to fabricate chitosan (CS)+polyethylene oxide (PEO)/polycaprolactone (PCL) nanofibrous mats, wherein RSV was incorporated within the core of nanofibers. By optimizing the relevant parameters of the electrospinning process, the mats' surface was further modified using plasma treatment. The fibers' shape, structure, and thermal stability were characterized. The wettability, and degradation properties of the fabricated mats were also examined. In vitro studies were conducted to examine the release behavior of RSV. Additionally, the capability of MSCs to survive and differentiate into osteocytes when cultured on nanofibers containing RSV was evaluated. Results: Results demonstrated the successful fabrication of CS + PEO + RSV/PCL core/shell mats with a core diameter of approximately 370 nm and a shell thickness of around 70 nm under optimized conditions. Plasma treatment was found to enhance the wettability and drug-release behavior of the mats. The nanofibrous structure, serving as a carrier for RSV, exhibited increased proliferation of MSCs and enhanced osteogenic differentiation. Conclusion: Therefore, it can be concluded that CS + PEO + RSV/PCL core/shell nanofibrous structure can be utilized as a sustained-release platform for RSV over an extended period, making it a promising candidate for guided bone regeneration.

Engineered biomimetic micro/nano-materials for tissue regeneration

The incidence of tissue and organ damage caused by various diseases is increasing worldwide. Tissue engineering is a promising strategy of tackling this problem because of its potential to regenerate or replace damaged tissues and organs. The biochemical and biophysical cues of biomaterials can stimulate and induce biological activities such as cell adhesion, proliferation and differentiation, and ultimately achieve tissue repair and regeneration. Micro/nano materials are a special type of biomaterial that can mimic the microstructure of tissues on a microscopic scale due to its precise construction, further providing scaffolds with specific three-dimensional structures to guide the activities of cells. The study and application of biomimetic micro/nano-materials have greatly promoted the development of tissue engineering. This review aims to provide an overview of the different types of micro/nanomaterials, their preparation methods and their application in tissue regeneration.

The Delivery and Activation of Growth Factors Using Nanomaterials for Bone Repair

Bone regeneration is a comprehensive process that involves different stages, and various growth factors (GFs) play crucial roles in the entire process. GFs are currently widely used in clinical settings to promote bone repair; however, the direct application of GFs is often limited by their fast degradation and short local residual time. Additionally, GFs are expensive, and their use may carry risks of ectopic osteogenesis and potential tumor formation. Nanomaterials have recently shown great promise in delivering GFs for bone regeneration, as they can protect fragile GFs and control their release. Moreover, functional nanomaterials can directly activate endogenous GFs, modulating the regeneration process. This review provides a summary of the latest advances in using nanomaterials to deliver exogenous GFs and activate endogenous GFs to promote bone regeneration. We also discuss the potential for synergistic applications of nanomaterials and GFs in bone regeneration, along with the challenges and future directions that need to be addressed.

Drug Delivery Systems in Regenerative Medicine: An Updated Review

Modern drug discovery methods led to evolving new agents with significant therapeutic potential. However, their properties, such as solubility and administration-related challenges, may hinder their benefits. Moreover, advances in biotechnology resulted in the development of a new generation of molecules with a short half-life that necessitates frequent administration. In this context, controlled release systems are required to enhance treatment efficacy and improve patient compliance. Innovative drug delivery systems are promising tools that protect therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. The present review provides an overview of different approaches used for drug delivery.

Nanofiber reinforced alginate hydrogel for leak-proof delivery and higher stress loading in nucleus pulposus

Injectable hydrogels effectively remodel degenerative nucleus pulposus (NP) with a resemblance to the in vivo microenvironment. However, the pressure within the intervertebral disc requires load-bearing implants. The hydrogel must undergo a rapid phase transition upon injection to avoid leakage. In this study, an injectable sodium alginate hydrogel was reinforced with silk fibroin nanofibers with core-shell structures. The nanofiber-embedded hydrogel provided support to adjacent tissues and facilitated cell proliferation. Platelet-rich plasma (PRP) was incorporated into the core-shell nanofibers for sustained release and enhanced NP regeneration. The composite hydrogel exhibited excellent compressive strength and enabled leak-proof delivery of PRP. In rat intervertebral disc degeneration models, radiography and MRI signal intensities were significantly reduced after 8 weeks of injections with the nanofiber-reinforced hydrogel. The biomimetic fiber gel-like structure was constructed in situ, providing mechanical support for NP repair, promoting the reconstruction of the tissue microenvironment, and finally realizing the regeneration of NP.

Electrospun Fibers: Versatile Approaches for Controlled Release Applications

Electrospinning has been one of the most attractive methods of fiber fabrication in the last century. A lot of studies have been conducted, especially in tissue engineering and drug delivery using electrospun fibers. Loading many different drugs and bioactive agents on or within these fibers potentiates the efficacy of such systems; however, there are still no commercial products with this technology available in the market. Various methods have been developed to improve the mechanical and physicochemical behavior of structures toward more controllable delivery systems in terms of time, place, or quantity of release. In this study, most frequent methods used for the fabrication of controlled release electrospun fibers have been reviewed. Although there are a lot of achievements in the fabrication of controlled release fibers, there are still many challenges to be solved to reach a qualified, reproducible system applicable in the pharmaceutical industry.

Tailor-made natural and synthetic grafts for precise urethral reconstruction

Injuries to the urethra can be caused by malformations, trauma, inflammation, or carcinoma, and reconstruction of the injured urethra is still a significant challenge in clinical urology. Implanting grafts for urethroplasty and end-to-end anastomosis are typical clinical interventions for urethral injury. However, complications and high recurrence rates remain unsatisfactory. To address this, urethral tissue engineering provides a promising modality for urethral repair. Additionally, developing tailor-made biomimetic natural and synthetic grafts is of great significance for urethral reconstruction. In this work, tailor-made biomimetic natural and synthetic grafts are divided into scaffold-free and scaffolded grafts according to their structures, and the influence of different graft structures on urethral reconstruction is discussed. In addition, future development and potential clinical application strategies of future urethral reconstruction grafts are predicted.

Fabrication of functional and nano-biocomposite scaffolds using strontium-doped bredigite nanoparticles/polycaprolactone/poly lactic acid via 3D printing for bone regeneration

Bone tissue engineering is a field to manufacture scaffolds for bone defects that cannot repair without medical interventions. Ceramic nanoparticles such as bredigite have importance roles in bone regeneration. We synthesized a novel strontium (Sr) doped bredigite (Bre) nanoparticles (BreSr) and then developed new nanocomposite scaffolds using polycaprolactone (PCL), poly lactic acid (PLA) by the 3D-printing technique. Novel functional nanoparticles were synthesized and characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS: map). The nanoparticles were uniformly distributed in the polymer matrix composites. The 3D- printed scaffolds were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), degradation rate porosity, mechanical tests, apatite formation and cell culture. Degradation rate and mechanical strength were increased in the PLA/PCL/Bre-5%Sr nanocopmposite scaffolds.. Hydroxyapatite crystals were also created on the scaffold surface in the bioactivity test. The scaffolds supported viability and proliferation of human osteoblasts. Gene expression and calcium deposition in the samples containing nanoparticles indicated statistical different than the scaffolds without nanoparticles. The nanocomposite scaffolds were implanted into the critical-sized calvarial defects in rat for 3 months. The scaffolds containing Bre-Sr ceramic nanoparticles exhibited the best potential to regenerate bone tissue.

Polycaprolactone scaffolds as a biomaterial for cementoblast delivery: An in vitro study

OBJECTIVE

To define the potential of polycaprolactone (PCL) scaffold for cementoblast delivery.

BACKGROUND

Dental cementum is critical for tooth attachment and position, and its regenerative capabilities remain unpredictable.

METHODS

PCL scaffolds were manufactured by the electrospinning technique at 10% and 20% (w/v) and seeded with cementoblasts (OCCM-30). Scaffolds were characterized for their morphology and biological performance by scanning electron microscopy (SEM), confocal and conventional histology, cytocompatibility (PrestoBlue assay), gene expression (type I collagen - Col1; bone sialoprotein - Bsp; runt-related transcription factor 2 - Runx-2; alkaline phosphatase - Alpl; osteopontin - Opn; osteocalcin - Ocn, osterix - Osx), and the potential to induce extracellular matrix deposition and mineralization in vitro.

RESULTS

Overall, data analysis showed that PCL scaffolds allowed cell adhesion and proliferation, modulated the expression of key markers of cementoblasts, and led to enhanced extracellular matrix deposition and calcium deposition as compared to the control group.

CONCLUSION

Altogether, our findings allow concluding that PCL scaffolds are a viable tool to culture OCCM-30 cells, leading to an increased potential to promote mineralization in vitro. Further studies should be designed in order to define the clinical relevance of cementoblast-loaded PCL scaffolds to promote new cementum formation.

In vitro and in vivo biocompatibility of decellularized cellulose scaffolds functionalized with chitosan and platelet rich plasma for tissue engineering applications

This study describes the fabrication of cellulose scaffold (CS) and cellulose-chitosan (CS/CHI) scaffolds from the immature endosperm of Borassus flabellifer (Linn.) (BF) loaded with platelet rich plasma (PRP). Thus, developed scaffolds were evaluated for their physicochemical and mechanical behavior, growth factor release and biological performance. Additionally, in vivo response was assessed in a sub cutaneous rat model to study vascularization, host inflammatory response and macrophage polarization. The results of this study demonstrated that CS and CS/CHI scaffolds with PRP demonstrated favorable physiochemical and morphogical properties. The scaffold groups CS-PRP and CS/CHI-PRP were able to release growth factors in a well sustained manner under physiological conditions. The presence of PRP in cellulosic scaffolds did show significant differences in their behavior when investigated under in vitro studies, where the release of diverse cytokines improved the cellular proliferation and differentiation of osteoblasts. Finally, the PRP enriched scaffolds when studied under in vivo conditions showed increased angiogenesis and re-epithelialization with adequate collagen deposition and tissue remodeling. Our results suggest that besides the conventional carrier systems, this new-generation of plant-based cellulosic scaffolds with/without any modification can serve as a suitable carrier for PRP encapsulation and release, which can be used in numerous tissue regenerative therapies.

Investigation of the synergistic effect of platelet-rich plasma and polychromatic light on human dermal fibroblasts seeded chitosan/gelatin scaffolds for wound healing

Conventional wound healing treatments are insufficient for chronic wounds caused by factors such as senescence of fibroblasts, reduced growth factor synthesis, and poor angiogenesis. Recently, tissue engineering approaches have been investigated to develop effective therapies. In this study, a biochemical/biophysical stimulant-based 3D system was developed for the healing of chronic wounds. In this direction, genipin crosslinked chitosan (CHT)/gelatin (GEL) scaffolds were fabricated by freeze-drying and loaded with platelet-rich plasma (PRP). The scaffolds were seeded with human dermal fibroblasts and then, polychromatic light in near infrared region (NIR) was applied to the scaffolds for activating the platelets and stimulating the fibroblasts (photoactivation, PAC). Thus, fibroblasts were stimulated both chemically and physically by PRP and light, respectively. Cell migration, proliferation, morphology, gene expressions and reactive oxygen species (ROS) activity were evaluated in-vitro. Laminin and collagen 4 expressions that are important for extracellular matrix (ECM) formation, and PDGF (Platelet-derived growth factor) and VEGF (Vascular endothelial growth factor) expressions that are important for vascularization significantly increased in the presence of both PRP and light. Besides, PRP and light improved cell migration in 3D core-and shell model synergistically. Hydrogen peroxide content decreased in both PRP and light, indicating inhibition of ROS production. It was concluded that the stimulation of platelets with light in the NIR has a great potential to use for both platelets activation and stimulation of fibroblasts. As a result, an effective therapy can be developed for chronic wounds by using scaffold-based 3D systems together with PRP and photostimulation.

Precision-engineered niche for directed differentiation of MSCs to lineage-restricted mineralized tissues

The major difference between tissue healing and regeneration is the extent of instructional cues available to precisely direct the biological response. A classic example is reparative or osteodentin that is seen in response to physicochemical injury to the pulp-dentin complex. Dentin regeneration can direct the differentiation of dental stem cells using concerted actions of both soluble (biomolecules, agonists, and antagonists) and insoluble (matrix topology) cues. The major purpose of this study was to examine the synergistic combination of two discrete biomaterial approaches by utilizing nanofiber scaffolds in discrete configurations (aligned or random) with incorporated polymeric microspheres capable of controlled release of growth factors. Further, to ensure appropriate disinfection for clinical use, Radio-Frequency Glow Discharge (RFGD) treatments were utilized, followed by seeding with a mesenchymal stem cell (MSC) line. SEM analysis revealed electrospinning generated controlled architectural features that significantly improved MSC adhesion and proliferation on the aligned nanofiber scaffolds compared to randomly oriented scaffolds. These responses were further enhanced by RFGD pre-treatments. These enhanced cell adhesion and proliferative responses could be attributed to matrix-induced Wnt signaling that was abrogated by pre-treatments with anti-Wnt3a neutralizing antibodies. Next, we incorporated controlled-release microspheres within these electrospun scaffolds with either TGF-β1 or BMP4. We observed that these scaffolds could selectively induce dentinogenic or osteogenic markers (DSPP, Runx2, and BSP) and mineralization. This work demonstrates the utility of a novel, modular combinatorial scaffold system capable of lineage-restricted differentiation into bone or dentin. Future validation of this scaffold system in vivo as a pulp capping agent represents an innovative dentin regenerative approach capable of preserving tooth pulp vitality.

Chitosan-dipotassium orthophosphate lyophilizate: a novel in situ thermogel carrier system of allogeneic platelet lysate growth factors

The clinical success of platelet-rich plasma (PRP) is constrained by its limited mechanical strength, rapid disintegration by lytic enzymes, and the consequent short-term release of bioactive growth factors (GFs). Recently, attempts to formulate PRP and other hemoderivatives, such as platelet lysate (PL) have been underway. The current study aimed to formulate allogeneic freeze-dried human platelet lysate (HPL) onto lyophilized chitosan - dipotassium hydrogen orthophosphate (CS/DHO) thermo-sensitive scaffolds. A systemic approach was employed to optimize freeze-drying (FD) procedures targeting predefined critical quality attributes (CQAs). Thermal behavior, vibrational spectroscopy, morphological and moisture content analyses were used to detect possible protein destabilization during formulation and suboptimal cake properties. The effect of CS/DHO concentrations on thermo-responsiveness and release kinetics were investigated. Finally, six-months stability and cytotoxicity studies were carried out. An optimized lyophilizate was attainable with residual moisture of less than 5% and thermoresponsive to 33 °C in less than 3 min. HPL proteins were sustainedly released over five days in a pH-sensitive manner. The stability study indicated plausible physical and biochemical stability. Cell viability testing supported the cytocompatibility of the system. Finally, the lyophilizate variant of CS/DHO thermogel overcomes limited storage stability previously posed as a challenge in freshly prepared thermogels. The developed system overcomes the drawbacks of currently used PRP treatment and provides a novel GF-rich scaffold for wound repair.

A Nanofiber Mat With Dual Bioactive Components and a Biomimetic Matrix Structure for Improving Osteogenesis Effect

The challenge of effectively regenerating bone tissue through tissue engineering technology is that most tissue engineering scaffolds cannot imitate the three-dimensional structure and function of the natural extracellular matrix. Herein, we have prepared the poly(L-lactic acid)–based dual bioactive component reinforced nanofiber mats which were named as poly(L-lactic acid)/bovine serum albumin/nanohydroxyapatite (PLLA/BSA/nHAp) with dual bioactive components by combining homogeneous blending and electrospinning technology. The results showed that these nanofiber mats had sufficient mechanical properties and a porous structure suitable for cell growth and migration. Furthermore, the results of cell experiments in vitro showed that PLLA/BSA/nHAp composite nanofiber mat could preferably stimulate the proliferation of mouse osteoblastic cells (MC3T3 cells) compared with pure PLLA nanofiber mats. Based on these results, the scaffolds developed in this study are considered to have a great potential to be adhibited as bone repair materials.

Tension Stimulation of Tenocytes in Aligned Hyaluronic Acid/Platelet-Rich Plasma-Polycaprolactone Core-Sheath Nanofiber Membrane Scaffold for Tendon Tissue Engineering

To recreate the in vivo niche for tendon tissue engineering in vitro, the characteristics of tendon tissue underlines the use of biochemical and biophysical cues during tenocyte culture. Herein, we prepare core-sheath nanofibers with polycaprolactone (PCL) sheath for mechanical support and hyaluronic acid (HA)/platelet-rich plasma (PRP) core for growth factor delivery. Three types of core-sheath nanofiber membrane scaffolds (CSNMS), consisting of random HA-PCL nanofibers (Random), random HA/PRP-PCL nanofibers (Random+) or aligned HA/PRP-PCL (Align⁺) nanofibers, were used to study response of rabbit tenocytes to biochemical (PRP) and biophysical (fiber alignment) stimulation. The core-sheath structures as well as other pertinent properties of CSNMS have been characterized, with Align⁺ showing the best mechanical properties. The unidirectional growth of tenocytes, as induced by aligned fiber topography, was confirmed from cell morphology and cytoskeleton expression. The combined effects of PRP and fiber alignment in Align⁺ CSNMS lead to enhanced cell proliferation rates, as well as upregulated gene expression and marker protein synthesis. Another biophysical cue on tenocytes was introduced by dynamic culture of tenocyte-seeded Align⁺ in a bioreactor with cyclic tension stimulation. Augmented by this biophysical beacon from mechanical loading, dynamic cell culture could shorten the time for tendon maturation in vitro, with improved cell proliferation rates and tenogenic phenotype maintenance, compared to static culture. Therefore, we successfully demonstrate how combined use of biochemical/topographical cues as well as mechanical stimulation could ameliorate cellular response of tenocytes in CSNMS, which can provide a functional in vitro environmental niche for tendon tissue engineering.

Enhanced bone tissue regeneration via bioactive electrospun fibrous composite coated titanium orthopedic implant

One of the very reliable, attractive, and cheapest techniques for synthesizing nanofibers for biomedical applications is electrospinning. Here, we have created a novel nanofibrous composite coated Ti plate to mimic an Extra Cellular Matrix (ECM) of native bone in order to enhance the bone tissue regeneration. An electrospun fibrous composite was obtained by the combination of minerals (Zn, Mg, Si) substituted hydroxyapatite (MHAP)/Polyethylene Glycol (PEG)/Cissus quadrangularis (CQ) extract. Fibrous composite's functionality, phase characteristics, and morphology were evaluated by FT-IR, XRD, and SEM techniques, respectively. The average fiber diameter of MHAP/PVA had decreased from ~274 to ~255 nm after incorporating PEG polymer. That further increased from ~255 to ~275 nm after adding CQ extract. Besides the bioactivity in SBF solution, the degradable nature was confirmed by immersing the fibrous composite in Tris-HCL solution. The degradable studies evaluate that the composite was degraded depending on time, and it degrades about 9.42% after 7 days of immersion. Osteoblasts like MG-63 cells differentiation, proliferation, and calcium deposition were also determined. These results show that this new fibrous composite exhibits advanced osteoblasts properties. Thus, we concluded that this new fibrous scaffold coated Ti implant could act as a better implant to mimic ECM of bone structure and to improve osteogenesis during bone regeneration.

Effects of porcine bone marrow-derived platelet-rich plasma on bone marrow-derived mesenchymal stem cells and endothelial progenitor cells

This study investigated the abundance of pro-regenerative growth factors in bone marrow-derived platelet-rich plasma (BM-PRP) and their effects on bone marrow-derived mesenchymal stem cells (BM-MSC) and bone marrow-derived endothelial progenitor cells (BM-EPC). Four 4-5 months-old domestic pigs were included, and each underwent bone marrow aspiration from its humerus bones and processed into bone marrow aspiration concentrate (BMAC) samples. The plasma and cellular portions of BMAC were subsequently separated and collected. The concentration of growth factors including BMP-2, PDGF-BB, TGF-β1 and VEGF in the plasma portion was measured and compared between BM-PRP and bone marrow-derived platelet-poor plasma (BM-PPP). It was found that platelet count was significantly higher in BM-PRP than in BM-PPP, but the concentration of above-mentioned growth factors was not significantly different between BM-PRP and BM-PPP. As most existing literature has indicated the regenerative potency of PRP, this study focused on assessing the effect of BM-PRP treatment on BM-MSC and BM-EPC proliferation, osteogenic differentiation and angiogenesis capacity by comparing samples with 2.5% BM-PRP treatment and samples without BM-PRP treatment (control). In response to BM-PRP treatment, the cellular doubling time increased with culturing time and was significantly shorter in the BM-PRP-treated samples than in control samples. For osteogenic differentiation, BM-PRP-treated BM-MSCs demonstrated a time-dependent increase in alkaline phosphatase (ALP) activity and expression levels of osteogenic differentiation markers. For the expression of angiogenic genes, none of the differences reached statistical significance despite a tendency of stronger expression at day 18 in BM-PRP-treated BM-EPCs. In conclusion, this in vitro study suggests that most BMP-2, PDGF-BB, TGF-β1 and VEGF-A contained in BM-PRP are not platelet-released and BM-PRP may have some stimulation (less than 1-fold) for MSC, EPC proliferation and MSC osteogenic differentiation.

Platelet-rich fibrin-loaded PCL/chitosan core-shell fibers scaffold for enhanced osteogenic differentiation of mesenchymal stem cells

Here, we fabricated the platelet-rich fibrin (PRF)-loaded PCL/chitosan (PCL/CS-PRF) core-shell nanofibrous scaffold through a coaxial electrospinning method. Our goal was to evaluate the effect of CS-RPF in the core layer of the nanofibrous on the osteogenic differentiation of human mesenchymal stem cells (HMSCs). The elastic modulus of PCL/CS-PRF core-shell scaffold (44 MPa) was about 1.5-fold of PCL/CS scaffold (25 MPa). The specific surface area of the scaffolds increased from 9.98 m²/g for PCL/CS scaffold to 16.66 m²/g for the PCL/CS-PRF core-shell nanofibrous scaffold. Moreover, the release rate of PRF from PCL/CS-PRF nanofibrous scaffold was measured to be 24.50% after 10 days which showed slow and sustained release of PRF from the nanofibrous. The formation of Ca-P on the surface of scaffold immersed in simulated body fluid solution indicated the suitable osteoconductivity of PCL/CS-PRF core-shell nanofibrous scaffold. Also, the value of ALP activity and calcium deposited on the surface of PCL/CS-PRF core-shell nanofibrous scaffold were 81.97 U/L and 40.33 μg/scaffold, respectively after 14 days, which confirmed the significantly higher amounts of ALP and calcium deposition on the scaffold containing PRF compared to PCL/CS scaffold. Due to higher hydrophilicity and porosity of PCL/CS-PRF core-shell nanofibrous scaffold compared to PCL/CS scaffold, a better bone cell growth on surface of PCL/CS-PRF scaffold was observed. The Alizarin red-positive area was significantly higher on PCL/CS-PRF scaffold compared to PCL/CS scaffold, indicating more calcium deposition and osteogenic differentiation of HMSCs in the presence of PRF. Our findings demonstrate that PCL/CS-PRF core-shell scaffolds can provide a strong construct with improved osteogenic for bone tissue engineering applications.

Three dimensional nanofibrous and compressible poly(L-lactic acid) bone grafts loaded with platelet-rich plasma

In this study, nanofibrous matrices of poly(L-lactic acid)-hydroxyapatite (PLLA-HAp) were successfully fabricated by three-dimensional (3D) electrospinning for use in the treatment of irregular bone damages. Compressibility analysis showed that 3D nanofibrous grafts occupied at least 2-fold more volume than their 2D form and they can easily take shape of the defect zone with irregular geometry. Moreover, the compression moduli of the PLLA and PLLA-HAp grafts were calculated as 8.0 ± 3.0 kPa and 11.8 ± 3.9 kPa, respectively, while the strain values of the same samples at the maximum load of 600 kPa were 164 ± 28% and 130 ± 20%, respectively. Treatment of the grafts with aqueous sodium hydroxide solution increased the surface roughness and thus the alloplastic graft materials (PLLA-HAp/M) protecting the fiber morphology were produced successfully. Then, platelet-rich plasma (PRP) was loaded into the surface modified grafts and activated with 10% calcium chloride. The efficiency of the activation was evaluated with flow cytometry and it was found that after activation the percentages of CD62 (P-selectin) and CD41/61 (glycoprotein IIb/IIIa) proteins increased approximately 4-fold. Surface hydrophilicity and biological activity of the PLLA-HAp grafts were enhanced by fibrin coating after PRP activation. Thein vitrocell culture studies which were carried out by using mouse pre-osteoblasts (MC3T3-E1) showed that graft materials supported by PRP increased cellular proliferation and osteogenic differentiation significantly. Thein vivoresults demonstrated that compared with bare PLLA-HAp/M grafts, the PRP loaded grafts (PRP-PLLA-HAp/M) induced significantly greater bone formation based on computed tomography, histological and immunohistochemical analyses. Our findings suggest that 3D PLLA nanofibrous matrices can be used as a graft material for irregular bone defects especially when combined with PRP as an osteogenic induction agent.

Design and applications of protein delivery systems in nanomedicine and tissue engineering

Proteins are biological macromolecules involved in a wide range of biological functions, which makes them very appealing as therapeutics agents. Indeed, compared to small molecule drugs, their endogenous nature ensures their biocompatibility and biodegradability, they can be used in a large range of applications and present a higher specificity and activity. However, they suffer from unfolding, enzymatic degradation, short half-life and poor membrane permeability. To overcome such drawbacks, the development of protein delivery systems to protect, carry and deliver them in a controlled way have emerged importantly these last years. In this review, the formulation of a wide panel of protein delivery systems either in the form of polymer or inorganic nanoengineered colloids and scaffolds are presented and the protein loading and release mechanisms are addressed. A section is also dedicated to the detection of proteins and the characterization methods of their release. Then, the main protein delivery systems developed these last three years for anticancer, tissue engineering or diabetes applications are presented, as well as the major in vivo models used to test them. The last part of this review aims at presenting the perspectives of the field such as the use of protein-rich material or the sequestration of proteins. This part will also deal with less common applications and gene therapy as an indirect method to deliver protein.

Controlled Delivery of Growth Factor by Hierarchical Nanostructured Core-Shell Nanofibers for the Efficient Repair of Critical-Sized Rat Calvarial Defect

Electrospun nanofibers have received much attention as bone tissue-engineered scaffolds for their capacity to mimic the structure of natural extracellular matrix (ECM). Most studies have reproduced nanofibers with smooth surface for tissue engineering. This is quite different from the triple-helical nanotopography of natural collagen nanofibrils. In this study, hierarchical nanostructures were coated on the surface of drug-loaded core-shell nanofibers to mimic natural collagen nanofibrils. The nanoshish-kebab (SK) structure was decorated regularly on the surface of the nanofibers, and the inner-loaded bone morphogenetic protein 2 (BMP2) exhibited a gentle release pattern, similar to a zero-order release pattern in kinetics. The in vitro study also showed that the SK structure could accelerate cell proliferation, attachment, and osteogenic differentiation. Four groups of scaffolds were implanted in vivo to repair critical-sized rat calvarial defects: (1) PCL/PVA (control); (2) SK-PCL/PVA; (3) PCL/PVA-BMP2; and (4) SK-PCL/PVA-BMP2. Much more bone was formed in the SK-PCL/PVA group (24.57 ± 3.81%) than in the control group (1.21 ± 0.23%). The BMP2-loaded core-shell nanofibers with nanopatterned structure (SK-PCL/PVA-BMP2) displayed the best repair efficacy (76.38 ± 4.13%), followed by the PCL/PVA-BMP2 group (39.86 ± 5.74%). It was believed that the hierarchical nanostructured core-shell nanofibers could promote osteogeneration and that the SK structure showed synergistic ability with nanofiber-loaded BMP2 in vivo for bone regeneration. Thus, this BMP2-loaded core-shell nanofiber scaffold with hierarchical nanostructure holds great potential for bone tissue engineering applications.

Washed Equine Platelet Extract as an Anti-Inflammatory Biologic Pharmaceutical

Mammalian platelets participate in the immediate tissue injury response by initiating coagulation and further promoting tissue injury mitigation and repair. The latter properties are deployed following platelet release of presynthetized morphogens, cytokines, and growth and chemotactic factors, which launch a tissue regenerative, angiogenic, and anti-inflammatory program. Several blood-derived biologic products, like platelet-rich plasma (PRP) and platelet lysate (PL), are currently on the market to allow proper healing and tissue regeneration. However, not all growth factors are released from the platelets and the final products contain plasma proteins such as albumin, fibrinogen, complement, and immunoglobulins, increasing the risks of serum sickness or allergic reaction. To address this problem, we developed a new platelet extract where equine blood platelets are concentrated, washed, and thereafter lysed by detergent Triton X-114. Distinct from PRP, this extract is devoid of albumin, fibrinogen, and immunoglobulins and is 266-fold enriched in platelet-derived growth factor content relative to PRP. Washed equine platelet extract (WEPLEX) is amenable to lyophilization without loss of biological activity. In vitro, WEPLEX significantly inhibits human and equine T cell proliferative response to phytohemagglutinin and also polarizes murine CD45⁺/CD11b⁺ peritoneal macrophages to an IL-10⁺ M2-like phenotype. In vivo, WEPLEX substantially improves clinical outcome of murine experimental dextran sulfate sodium colitis. We propose that equine-sourced, zoonosis-free WEPLEX may serve as an anti-inflammatory biological therapy across mammalian species.

Epidermal stimulating factors-gelatin/polycaprolactone coaxial electrospun nanofiber: ideal nanoscale material for dermal substitute

In this study, an ideal nano-scale material, named epidermal stimulating (ES) factors-gelatin/polycaprolactone (GT/PCL) nanofiber, was fabricated using a coaxial electrospinning technique. The ES-GT/PCL nanofibers possessed a highly porous structure with qualified mechanical properties for transplantation. With ES factors stored in the core and GT/PCL in the shell, the ES factors could be protected and released in a sustained manner. After seeding L929 cell line on ES-GT/PCL nanofibers for 7 days in vitro, the proliferation of cells was nearly 1.5 folds compared to the control group. The in vivo study showed that ES-GT/PCL nanofibers can accelerate skin wound healing rate during the healing course, especially on the early stage. The epidermal and dermal thickness, as well as skin appendages and fat tissue, were the most similar to the native skin. These findings provided valuable insights into the addition of multiple bioactive factors to nanometre biomaterials, and optimising the advantages of the compositions as a promising potential dermal substitute construct.

Chitosan/polydopamine layer by layer self-assembled silk fibroin nanofibers for biomedical applications

Silk fibroin (SF) is increasingly needed in tissue engineering for its superior biocompatibility. However, the practical applications of pure SF biomaterials confront bacterial infection problems. In this study, chitosan (CS) and polydopamine (PDA) were introduced into electrospun nanofibrous SF mats through layer-by-layer self-assembly (LBL) to obtain enhanced antibacterial ability and cytocompatibility. The surface morphology and composition analysis confirmed the successful deposition. After depositing 15 bilayers, the tensile modulus of the mats in wet condition increased from 2.16 MPa (pristine SF mats) to 4.89 MPa. A trend towards better hydrophilicity performance was also recorded with more bilayers coating on the mats. Besides, LBL structured mats showed improved antibacterial ability of more than 98 % against E. coli and S. aureus. In addition, advancement in biocompatibility was observed during the proliferation experiment of L929 cells. Overall, the deposition of CS and PDA may further expand the use of SF in biomedical field.

Electrospun Nanofibers for Improved Angiogenesis: Promises for Tissue Engineering Applications

Angiogenesis (or the development of new blood vessels) is a key event in tissue engineering and regenerative medicine; thus, a number of biomaterials have been developed and combined with stem cells and/or bioactive molecules to produce three-dimensional (3D) pro-angiogenic constructs. Among the various biomaterials, electrospun nanofibrous scaffolds offer great opportunities for pro-angiogenic approaches in tissue repair and regeneration. Nanofibers made of natural and synthetic polymers are often used to incorporate bioactive components (e.g., bioactive glasses (BGs)) and load biomolecules (e.g., vascular endothelial growth factor (VEGF)) that exert pro-angiogenic activity. Furthermore, seeding of specific types of stem cells (e.g., endothelial progenitor cells) onto nanofibrous scaffolds is considered as a valuable alternative for inducing angiogenesis. The effectiveness of these strategies has been extensively examined both in vitro and in vivo and the outcomes have shown promise in the reconstruction of hard and soft tissues (mainly bone and skin, respectively). However, the translational of electrospun scaffolds with pro-angiogenic molecules or cells is only at its beginning, requiring more research to prove their usefulness in the repair and regeneration of other highly-vascularized vital tissues and organs. This review will cover the latest progress in designing and developing pro-angiogenic electrospun nanofibers and evaluate their usefulness in a tissue engineering and regenerative medicine setting.

Electrospun fibers based on carbohydrate gum polymers and their multifaceted applications

Electrospinning has garnered significant attention in view of its many advantages such as feasibility for various polymers, scalability required for mass production, and ease of processing. Extensive studies have been devoted to the use of electrospinning to fabricate various electrospun nanofibers derived from carbohydrate gum polymers in combination with synthetic polymers and/or additives of inorganic or organic materials with gums. In view of the versatility and the widespread choice of precursors that can be deployed for electrospinning, various gums from both, the plants and microbial-based gum carbohydrates are holistically and/or partially included in the electrospinning solution for the preparation of functional composite nanofibers. Moreover, our strategy encompasses a combination of natural gums with other polymers/inorganic or nanoparticles to ensue distinct properties. This early established milestone in functional carbohydrate gum polymer-based composite nanofibers may be deployed by specialized researchers in the field of nanoscience and technology, and especially for exploiting electrospinning of natural gums composites for diverse applications.

Platelet-inspired therapeutics: current status, limitations, clinical implications, and future potential

Recent research has been successful in demonstrating the importance of the addition of platelets to the field of cell-mediated therapeutics, by making use of different platelet forms to design modalities able to positively impact a wide range of diseases. A key obstacle hindering the success of conventional therapeutic interventions is their inability to produce targeted treatment, resulting in a number of systemic side effects and a longer duration for the onset of action to occur. An additional challenge facing current popular therapeutic interventions is biocompatibility of the system, resulting in the decline of patient compliance to treatment. In an attempt to address these challenges, the past few decades have been witness to the discovery and innovation of precision therapy, in order to achieve targeted treatment for an array of conditions, thereby superseding alternative mechanisms of treatment. Platelet-mediated therapeutics, as well as employing platelets as drug delivery vehicles, are key components in advancing precision therapy within research and in clinical settings. This novel approach is designed with the objective that the platelets retain their original structure and functions within the body, thereby mitigating biocompatibility challenges. In this article, we review the current significant impact that the addition of platelet-inspired systems has made on the field of therapeutics; explore certain limitations of each system, together with ideas on how to overcome them; and discuss the clinical implications and future potential of platelet-inspired therapeutics. Graphical abstract.

The Use of Electrospun Organic and Carbon Nanofibers in Bone Regeneration

There has been an increasing amount of research on regenerative medicine for the treatment of bone defects. Scaffolds are needed for the formation of new bone, and various scaffolding materials have been evaluated for bone regeneration. Materials with pores that allow cells to differentiate into osteocytes are preferred in scaffolds for bone regeneration, and porous materials and fibers are well suited for this application. Electrospinning is an effective method for producing a nanosized fiber by applying a high voltage to the needle tip containing a polymer solution. The use of electrospun nanofibers is being studied in the medical field, and its use as a scaffold for bone regeneration therapy has become a topic of growing interest. In this review, we will introduce the potential use of electrospun nanofiber as a scaffold for bone regenerative medicine with a focus on carbon nanofibers produced by the electrospinning method.

Biodegradable Polymers as Drug Delivery Systems for Bone Regeneration

Regenerative medicine has been widely researched for the treatment of bone defects. In the field of bone regenerative medicine, signaling molecules and the use of scaffolds are of particular importance as drug delivery systems (DDS) or carriers for cell differentiation, and various materials have been explored for their potential use. Although calcium phosphates such as hydroxyapatite and tricalcium phosphate are clinically used as synthetic scaffold material for bone regeneration, biodegradable materials have attracted much attention in recent years for their clinical application as scaffolds due their ability to facilitate rapid localized absorption and replacement with autologous bone. In this review, we introduce the types, features, and performance characteristics of biodegradable polymer scaffolds in their role as DDS for bone regeneration therapy.

Poly(Vinyl Alcohol)-Based Nanofibrous Electrospun Scaffolds for Tissue Engineering Applications

Tissue engineering (TE) holds an enormous potential to develop functional scaffolds resembling the structural organization of native tissues, to improve or replace biological functions and prevent organ transplantation. Amongst the many scaffolding techniques, electrospinning has gained widespread interest because of its outstanding features that enable the production of non-woven fibrous structures with a dimensional organization similar to the extracellular matrix. Various polymers can be electrospun in the form of three-dimensional scaffolds. However, very few are successfully processed using environmentally friendly solvents; poly(vinyl alcohol) (PVA) is one of those. PVA has been investigated for TE scaffolding production due to its excellent biocompatibility, biodegradability, chemo-thermal stability, mechanical performance and, most importantly, because of its ability to be dissolved in aqueous solutions. Here, a complete overview of the applications and recent advances in PVA-based electrospun nanofibrous scaffolds fabrication is provided. The most important achievements in bone, cartilage, skin, vascular, neural and corneal biomedicine, using PVA as a base substrate, are highlighted. Additionally, general concepts concerning the electrospinning technique, the stability of PVA when processed, and crosslinking alternatives to glutaraldehyde are as well reviewed.

Core-Shell Fibers: Design, Roles, and Controllable Release Strategies in Tissue Engineering and Drug Delivery

The key attributes of core-shell fibers are their ability to preserve bioactivity of incorporated-sensitive biomolecules (such as drug, protein, and growth factor) and subsequently control biomolecule release to the targeted microenvironments to achieve therapeutic effects. Such qualities are highly favorable for tissue engineering and drug delivery, and these features are not able to be offered by monolithic fibers. In this review, we begin with an overview on design requirement of core-shell fibers, followed by the summary of recent preparation methods of core-shell fibers, with focus on electrospinning-based techniques and other newly discovered fabrication approaches. We then highlight the importance and roles of core-shell fibers in tissue engineering and drug delivery, accompanied by thorough discussion on controllable release strategies of the incorporated bioactive molecules from the fibers. Ultimately, we touch on core-shell fibers-related challenges and offer perspectives on their future direction towards clinical applications.

An introduction to bone tissue engineering

Bone tissue has the capability to regenerate itself; however, defects of a critical size prevent the bone from regenerating and require additional support. To aid regeneration, bone scaffolds created out of autologous or allograft bone can be used, yet these produce problems such as fast degradation rates, reduced bioactivity, donor site morbidity or the risk of pathogen transmission. The development of bone tissue engineering has been used to create functional alternatives to regenerate bone. This can be achieved by producing bone tissue scaffolds that induce osteoconduction and integration, provide mechanical stability, and either integrate into the bone structure or degrade and are excreted by the body. A range of different biomaterials have been used to this end, each with their own advantages and disadvantages. This review will introduce the requirements of bone tissue engineering, beginning with the regeneration process of bone before exploring the requirements of bone tissue scaffolds. Aspects covered include the manufacturing process as well as the different materials used and the incorporation of bioactive molecules, growth factors and cells.

Tazarotene Released from Aligned Electrospun Membrane Facilitates Cutaneous Wound Healing by Promoting Angiogenesis

Wound treatment is a long-lasting clinical issue. Poor angiogenesis leading to delayed wound closure causes huge challenges for healing. Functional electrospun membranes have been established as an efficient strategy to promote wound recovery by protecting and improving vascular regeneration. Here, we aimed to investigate the effect of tazarotene, an active drug for angiogenesis, loaded in aligned electrospun nanofibrous barrier on a soft tissue wound. This aligned membrane was arranged in a single direction, and tazarotene could be released from its nanofibers sustainably. The in vitro study demonstrated that compared with the random drug-loaded or other control groups, the aligned tazarotene-loaded membranes [poly-caprolactone (PCL)/AT] could stimulate proliferation, migration, angiogenesis, and vascular endothelial growth factor secretion and its gene expression of human umbilical vein endothelial cells. Furthermore, the in vivo model showed that the prepared tazarotene-loaded aligned membrane significantly accelerated the speed of healing, improved the neovascularization and re-epithelialization, and inhibited the inflammatory reaction in the wound area. All these results above indicated that the PCL/AT nanofibrous dressing, which could promote angiogenesis because of both stimulation of structure and chemical signals, is a promising wound-caring material.

A Novel Bilayer Polycaprolactone Membrane for Guided Bone Regeneration: Combining Electrospinning and Emulsion Templating

Guided bone regeneration is a common dental implant treatment where a barrier membrane (BM) is used between epithelial tissue and bone or bone graft to prevent the invasion of the fast-proliferating epithelial cells into the defect site to be able to preserve a space for infiltration of slower-growing bone cells into the periodontal defect site. In this study, a bilayer polycaprolactone (PCL) BM was developed by combining electrospinning and emulsion templating techniques. First, a 250 µm thick polymerised high internal phase emulsion (polyHIPE) made of photocurable PCL was manufactured and treated with air plasma, which was shown to enhance the cellular infiltration. Then, four solvent compositions were investigated to find the best composition for electrospinning a nanofibrous PCL barrier layer on PCL polyHIPE. The biocompatibility and the barrier properties of the electrospun layer were demonstrated over four weeks in vitro by histological staining. Following in vitro assessment of cell viability and cell migration, cell infiltration and the potential of PCL polyHIPE for supporting blood vessel ingrowth were further investigated using an ex-ovo chick chorioallantoic membrane assay. Our results demonstrated that the nanofibrous PCL electrospun layer was capable of limiting cell infiltration for at least four weeks, while PCL polyHIPE supported cell infiltration, calcium and mineral deposition of bone cells, and blood vessel ingrowth through pores.

Multi-Functional Electrospun Nanofibers from Polymer Blends for Scaffold Tissue Engineering

Electrospinning and polymer blending have been the focus of research and the industry for their versatility, scalability, and potential applications across many different fields. In tissue engineering, nanofiber scaffolds composed of natural fibers, synthetic fibers, or a mixture of both have been reported. This review reports recent advances in polymer blended scaffolds for tissue engineering and the fabrication of functional scaffolds by electrospinning. A brief theory of electrospinning and the general setup as well as modifications used are presented. Polymer blends, including blends with natural polymers, synthetic polymers, mixture of natural and synthetic polymers, and nanofiller systems, are discussed in detail and reviewed.