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

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

Graphene oxide-encapsulated baghdadite nanocomposite improved physical, mechanical, and biological properties of a vancomycin-loaded PMMA bone cement.

Polymethyl methacrylate (PMMA) bone cement is commonly used in orthopedic surgeries to fill the bone defects or fix the prostheses. These cements are usually containing amounts of a nonbioactive radiopacifying agent such as barium sulfate and zirconium dioxide, which does not have a good interface compatibility with PMMA, and the clumps formed from these materials can scratch metal counterfaces. In this work, graphene oxide encapsulated baghdadite (GOBgh) nanoparticles were applied as radiopacifying and bioactive agent in a PMMA bone cement containing 2 wt.% of vancomycin (VAN). The addition of 20 wt.% of GOBgh (GOBgh20) nanoparticles to PMMA powder caused a 33.6% increase in compressive strength and a 70.9% increase in elastic modulus compared to the Simplex® P bone cement, and also enhanced the setting properties, radiopacity, antibacterial activity, and the apatite formation in simulated body fluid. In vitro cell assessments confirmed the increase in adhesion and proliferation of MG-63 cells as well as the osteogenic differentiation of human adipose-derived mesenchymal stem cells on the surface of PMMA-GOBgh20 cement. The chorioallantoic membrane assay revealed the excellent angiogenesis activity of nanocomposite cement samples. In vivo experiments on a rat model also demonstrated the mineralization and bone integration of PMMA-GOBgh20 cement within four weeks. Based on the promising results obtained, PMMA-GOBgh20 bone cement is suggested as an optimal sample for use in orthopedic surgeries.

A double-layer cellulose/pectin-soy protein isolate-pomegranate peel extract micro/nanofiber dressing for acceleration of wound healing.

Multi-layered wound dressings can closely mimic the hierarchical structure of the skin. Herein, a double-layer dressing material is fabricated through electrospinning, comprised of a nanofibrous structure as a healing-support layer or the bottom layer (BL) containing pectin (Pec), soy protein isolate (SPI), pomegranate peel extract (P), and a cellulose (Cel) microfiber layer as a protective/monitoring layer or top layer (TL). The formation of a fine bilayer structure was confirmed using scanning electron microscopy. Cel/Pec-SPI-P dressing showed a 60.05 % weight loss during 7 days of immersion in phosphate buffered solution. The ultimate tensile strength, elastic modulus, and elongation at break for different dressings were within the range of 3.14-3.57 MPa, 32.26-36.58 MPa, and 59.04-63.19 %, respectively. The release of SPI and phenolic compounds from dressings were measured and their antibacterial activity was evaluated. The fabricated dressing was non-cytotoxic following exposure to human keratinocyte cells. The Cel/Pec-SPI-P dressing exhibited excellent cell adhesion and migration as well as angiogenesis. More importantly, in vivo experiments on Cel/Pec-SPI-P dressings showed faster epidermal layer formation, blood vessel generation, collagen deposition, and a faster wound healing rate. Overall, it is anticipated that the Cel/Pec-SPI-P bilayer dressing facilitates wound treatment and can be a promising approach for clinical use.

Asymmetric tri-layer sponge-nanofiber wound dressing containing insulin-like growth factor-1 and multi-walled carbon nanotubes for acceleration of full-thickness wound healing.

To more closely resemble the structure of natural skin, multi-layered wound dressings have been developed. Herein, a tri-layer wound dressing was prepared containing a polyacrylamide (PAAm)-Aloe vera (Alo) sponge that had been incorporated with insulin-like growth factor-1 (IGF1) to provide a porous absorbent layer, which was able to promote angiogenesis. Alo nanofibers with multi-walled carbon nanotubes (MWCNT) were electrospun into the bottom layer to increase cell behavior, and a small film of stearic acid was put as a top layer to avoid germy penetration. In comparison to bilayer dressing, the tensile strength increased by 17.0 % (from 0.200 ± 0.010 MPa to 0.234 ± 0.022 MPa) and the elastic modulus by 45.6 % (from 0.217 ± 0.003 MPa to 0.316 ± 0.012 MPa) in the presence of Alo nanofibers containing 0.5 wt% of MWCNT at the bottom layer of Trilayer0.5 dressing. The release profile of IGF1, the antibacterial activity and the degradability of different wound dressings were investigated. Trilayer0.5 indicated the highest cell viability, cell adhesion and angiogenic potential among the prepared dressing materials. In-vivo rat model revealed that the Trilayer0.5 dressing treated group had the highest rate of wound closure and wound healing within 10 days compared to other groups.

A 3D printed polylactic acid-Baghdadite nanocomposite scaffold coated with microporous chitosan-VEGF for bone regeneration applications.

Three-dimensional (3D) printing technology has become an advanced approach for fabricating patient-specific scaffolds with complex geometric shapes to replace damaged or diseased tissue. Herein, polylactic acid (PLA)-Baghdadite (Bgh) scaffold were made through the fused deposition modeling (FDM) 3D printing method and subjected to alkaline treatment. Following fabrication, the scaffolds were coated with either chitosan (Cs)-vascular endothelial growth factor (VEGF) or lyophilized Cs-VEGF known as PLA-Bgh/Cs-VEGF and PLA-Bgh/L.(Cs-VEGF), respectively. Based on the results, it was found that the coated scaffolds had higher porosity, compressive strength and elastic modulus than PLA and PLA-Bgh samples. Also, the osteogenic differentiation potential of scaffolds following culture with rat bone marrow-derived mesenchymal stem cells (rMSCs) was evaluated through crystal violet and Alizarin-red staining, alkaline phosphatase (ALP) activity and calcium content assays, osteocalcin measurements, and gene expression analysis. The release of VEGF from the coated scaffolds was assessed and also the angiogenic potential of scaffolds was evaluated. The sum of results presented in the current study strongly suggests that the PLA-Bgh/L.(Cs-VEGF) scaffold can be a proper candidate for bone healing applications.

PDGF and VEGF-releasing bi-layer wound dressing made of sodium tripolyphosphate crosslinked gelatin-sponge layer and a carrageenan nanofiber layer.

The use of dressings is one of the most common methods for wound treatment. Since most single-layer dressings cannot mimic the hierarchical structure of the skin well, multi-layer dressings have been considered. In this study, a bilayer dressing was fabricated using a gelatin sponge layer cross-linked with sodium tripolyphosphate (Gel-STPP) and a layer of carrageenan nanofibers containing platelet-rich fibrin (Carr-PRF). Chemical interactions between the two layers were characterized by FTIR, and the microstructure was visualized by SEM. It was found that the presence of Carr-PRF nanofiber layer increased tensile strength by 12.96 % (from 0.216 ± 0.015 to 0.268 ± 0.036 MPa) and elastic modulus by 56.70 % (from 0.388 ± 0.072 to 0.608 ± 0.029 MPa) compared to Gel-STPP sponge. Gel-STPP/Carr-PRF wound dressing had a 45.76 ± 4.18 % degradability after 7 days of immersion in phosphate buffered saline (PBS). PRF-containing bilayer wound dressing was able to sustainably release growth factors over 7 days. The Carr-PRF nanofiber layer coated on Gel-STPP sponge was an ideal environment for adhesion and proliferation of L929 cells. Gel-STPP/Carr-PRF bilayer dressing outperformed the other tested samples in terms of angiogenic potential. Average wound closure was 94.21 ± 2.06 % in Gel-STPP/Carr-PRF dressing treated rats after 14 days, and based on the histopathological and immunohistochemical examinations, the Gel-STPP/Carr-PRF dressing group augmented full-thickness wound healing, keratin layer and skin appendages formation after 14 days.

Three-dimensional printing of polycaprolactone/hydroxyapatite bone tissue engineering scaffolds mechanical properties and biological behavior.

Controlled pore size and desirable internal architecture of bone scaffolds play a significant role in bone regeneration efficiency. In addition to choosing appropriate materials, the manufacturing method is another significant factor in fabricating the ideal scaffold. In this study, scaffolds were designed and fabricated by the fused filament fabrication (FFF) technique. Polycaprolactone (PCL) and composites films with various percentages of hydroxyapatite (HA) (up to 20%wt) were used to fabricate filaments. The influence of (HA) addition on the mechanical properties of filaments and scaffolds was investigated. in vitro biological evaluation was examined as well as the apatite formation in simulated body fluid (SBF). The addition of HA particles increased the compressive strength and Young's modulus of filaments and consequently the scaffolds. Compared to PCL, Young's modulus of PCL/HA20% filament and three-dimensional (3D) printed scaffold has increased by 30% and 50%, respectively. Also, Young's modulus for all scaffolds was in the range of 30-70 MPa, which is appropriate to use in spongy bone. Besides, the MTT assay was utilized to evaluate cell viability on the scaffolds. All the samples had qualified cytocompatibility, and it would be anticipated that addition of HA particles raise the biocompatibility in vivo. Alkaline phosphatase (ALP) evaluation shows that the addition of HA caused higher ALP activity in the PCL/HA scaffolds than PCL. Furthermore, calcium deposition in the PCL/HA specimens is higher than control. In conclusion, the addition of HA particles into the PCL matrix, as well as utilizing an inexpensive commercial FFF device, lead to the fabrication of scaffolds with proper mechanical and biological properties for bone tissue engineering applications. Graphical abstract.

An integrated microfluidic device for stem cell differentiation based on cell-imprinted substrate designed for cartilage regeneration in a rabbit model.

Separating cells from the body and cultivating them in vitro will alter the function of cells. Therefore, for optimal cell culture in the laboratory, conditions similar to those of their natural growth should be provided. In previous studies, it has been shown that the use of cellular shape at the culture surface can regulate cellular function. In this work, the efficiency of the imprinting method increased by using microfluidic chip design and fabrication. In this method, first, a cell-imprinted substrate of chondrocytes was made using a microfluidic chip. Afterwards, stem cells were cultured on a cell-imprinted substrate using a second microfluidic chip aligned with the substrate. Therefore, stem cells were precisely placed on the chondrocyte patterns on the substrate and their fibroblast-like morphology was changed to chondrocyte's spherical morphology after 14-days culture in the chip without using any chemical growth factor. After chondrogenic differentiation and in vitro assessments (real-time PCR and immunocytotoxicity), differentiated stem cells were transferred on a collagen-hyaluronic acid scaffold and transplanted in articular cartilage defect of the rabbit. After 6 months, the post-transplantation analysis showed that the articular cartilage defect had been successfully regenerated in differentiated stem cell groups in comparison with the controls. In conclusion, this study showed the potency of the imprinting method for inducing chondrogenicity in stem cells, which can be used in clinical trials due to the safety of the procedure.

Fabrication of alginate modified brushite cement impregnated with antibiotic: Mechanical, thermal, and biological characterizations.

Treatment of postsurgical infections, associated with orthopedic surgeries, has been a major concern for orthopedics. Several strategies including systematic and local administration of antibiotics have been proposed to this regard. The present work focused on fabricating alginate (Alg) modified brushite (Bru) cements, which could address osteogeneration and local antibiotic demands. To find the proper method of drug incorporation, Gentamicin sulfate (Gen) was loaded into the samples in the form of solution or powder. Several characterization tests including compression test, morphology, cytotoxicity, and cell adhesion assays were carried out to determine the proper concentration of Alg as a modifier of the Bru cement. The results indicated that addition of 1 wt% Alg led to superior mechanical and biological properties of the cement. Moreover, Alg addition changed the morphology of the cement from plate and needle-like structures to petal-like structure. Fourier transform infrared spectroscopy results confirmed the successful loading of Gen on the cements, specifically when Gen solution was used, and X-Ray Diffractometer result indicated that Gen caused a decrease in crystalline size. Furthermore, thermal analysis revealed that Gen-loaded sample had more stable structure as the transformation temperature slightly shifted to a higher one. The stability study confirmed the chemical stability and adequate mechanical performance of the cements within 1 month of soaking time. Finally, the addition of Alg has a positive impact on the release behavior at low concentration of Gen solution so that 20% decrease within 2 weeks of release experiment was remarkably detected.

Laser irradiation affects the biological identity and cellular uptake of plasmonic nanoparticles.

The biological identity of nanoparticles (NPs) is defined by a protein layer formed on their surface, called protein corona (PC), once they meet the biological milieu. Any change in the PC composition may influence the biological fate of NPs. The PC composition is strongly dependent on several parameters including the physicochemical properties of NPs, and biological and environmental factors. As one of the main features of plasmonic NPs is their capacity to induce local heating by laser irradiation, we hypothesized that laser irradiation may change the biological identity of NPs and therefore alter their biological fate. To test this hypothesis, here we investigated the effects of either simultaneous or sequential laser irradiation on the conformations of a few proteins selected from two main categories of plasma proteins (i.e. human serum albumin and human fibrinogen) on the surfaces of gold nanorods (AuNRs). The outcomes revealed a significant role of laser irradiation on conformational changes of fibrinogen compared to albumin. Moreover, the effects of plasmonic heating - at various times - on the achieved corona composition from interactions of AuNRs and human plasma with various concentrations were monitored. Consequently, the cellular uptake of the corona coated AuNRs was measured in two cell types: malignant (MCF-7) and normal (MCF-10A) breast cell lines. The results demonstrated a substantial reduction in the cellular uptake of AuNRs in response to an increase in the laser irradiation time, especially in MCF-10A. Our results may pave the way for a mechanistic understanding of the biological identity of plasmonic NPs which in turn can help their safe and efficient clinical translations.

Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering.

Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples, respectively. With blending thermoplastic starch and ethylene vinyl alcohol, some properties of thermoplastic starch such as degradation rate and water absorption were modified. In addition, using nanoforsterite as the ceramic reinforcing phase resulted in the improvement of mechanical and biological traits. The addition of nanoforsterite decreased the weight loss of the thermoplastic starch and ethylene vinyl alcohol blend in simulated body fluid. Moreover, this addition modified the pH in the MTT (methyl thiazolyl tetrazolium) assay and stimulated the cell proliferation. Cell adhesion assays indicated a favorable interaction between cells and the biomaterial. The proposed nanocomposite has appropriate biocompatibility, as well as mechanical properties in order to be used in bone tissue engineering.