Fabrication of chitosan/gallic acid 3D microporous scaffold for tissue engineering applications

l-Arginine-Loaded Oxidized Isabgol/Chitosan-Based Biomimetic Composite Scaffold Accelerates Collagen Synthesis, Vascularization, and Re-epithelialization during Wound Healing in Diabetic Rats

Impaired wound healing in diabetic wounds is common due to infection, inflammation, less collagen synthesis, and vascularization. Diabetic wound healing in patients is still a challenge and needs an ideal wound dressing to treat and manage diabetic wounds. Herein, an efficacious wound dressing biomaterial was fabricated by cross-linking oxidized isabgol (Oisab) and chitosan (Cs) via trisodium trimetaphosphate and Schiff base bonds. l-Arginine (l-Arg) was incorporated as a bioactive substance in the Oisab + Cs scaffold to promote cell adhesion, cell proliferation, collagen synthesis, and vascularization. The fabricated scaffolds showed microporous networks in the scanning electron microscopy analysis. The scaffold also possessed excellent hemocompatibility. In vitro studies using fibroblasts (L929 and human dermal fibroblast cells) confirmed the cytocompatibility of these scaffolds. The results of the in vivo chicken chorioallantoic membrane assay confirmed the proangiogenic activity of the Oisab + Cs + l-Arg scaffolds. The wound-healing potential of these scaffolds was studied in streptozotocin-induced diabetic rats. This in vivo study showed that the period of epithelialization in the Oisab + Cs + l-Arg scaffold-treated wounds was 21.67 ± 1.6 days, which was significantly faster than the control (30.33 ± 2.5 days). Histological and immunohistochemical studies showed that the Oisab + Cs + l-Arg scaffolds significantly accelerated the rate of wound contraction by reducing inflammation, improving collagen synthesis, and promoting neovascularization. These findings suggest that the Oisab + Cs + l-Arg scaffolds could be beneficial in treating diabetic wounds in clinical applications.

Preparation and characterization of a jelly fig (Ficus awkeotsang Makino) polysaccharide-based bioactive 3D scaffold for improved vascularization and skin tissue engineering applications

Jelly fig polysaccharides (JFP) were extracted from Ficus awkeotsang Makino achenes. The yield of JFP was approximately 10-15 %. FT-IR spectrum of the extracted JFP confirmed that it was made of low methoxyl pectin (LMP). 3D scaffolds of JFP (JFP scaffold) were fabricated using ionic crosslinking of 2 % (w/v) JFP solution with Ca2+ ions and freeze-drying. The JFP scaffold showed 73.46 ± 1.97 % porosity and a 12-fold swelling capacity. The porous morphology was also observed in SEM micrographs. JFP scaffolds were completely degraded in 14 days when incubated in 1 mg/mL lysozyme solution, compared to the 50 % degradation observed in PBS alone. The antioxidant activity of the JFP and JFP scaffold was approximately 40 %. The hemolytic assay of the JFP scaffold showed <5 % (3.0 ± 0.4) RBC lysis. The cytocompatibility of the JFP scaffold was evaluated using L929 mouse fibroblasts and human dermal fibroblasts (HDF). The in vitro studies using L929 cells showed that the JFP scaffold is cytocompatible. HDF cells cultured in the presence of JFP scaffolds show a higher fold cell viability, proliferation, and migration. Collagen expression and deposition were also studied, and no significant changes occurred with JFP scaffold treatment. In vivo CAM assay showed an increase in the number and thickness of blood vessels by 1.185-fold and 1.19-fold, respectively. These results confirm the angiogenic property of the JFP scaffold. These biocompatible and bioactive properties of the JFP scaffold could be beneficial for tissue engineering and regenerative medicine applications.

Combination techniques towards novel drug delivery systems manufacturing: 3D PCL scaffolds enriched with tetracycline-loaded PVP nanoparticles

Drug delivery systems based on synthetic and natural polymers offer a new approach with a capacity to control the release of bio-active agents within time. In this work, we present different designs of Polycaprolactone (PCL) 3D scaffolds containing Polyvinylpyrrolidone (PVP) nanoparticles that can store a hydrophilic drug. The drug delivery system, combined of PCL and PVP polymers fabricated by additive manufacturing, aims for a solution for longer and more stabled drug delivery carrier. The drug, planned to be released to the targeted area, is sprayed with the electrospray method inside PVP nanoparticles on the different layers of the fabricated PCL scaffolds 3D printing. This makes obtaining a layered and porous scaffold and drug-loaded nanoparticles within this structure easier. Obtained PCL scaffolds containing Tetracyclines (Tet) loaded PVP nanoparticles showed that drug encapsulation into the interlayer extended the release time and exhibited a controlled release profile for days. Moreover, produced scaffolds have good biocompatibility and no harmful effects. The combination of 3D scaffolds and drug-loaded nanoparticles aims to develop new functional scaffolds by targeting more efficient and longer-lasting drug delivery.

Post grafted gallic acid to chitosan-Ag hybrid nanoparticles via free radical-induced grafting reactions

The present study proposes two unique systems using free radical-induced grafting reactions to combine Ag, chitosan (CS) and gallic acid (GA) into a single particulate nanostructure. GA-grafted-CS (GA-g-CS) was used to reduce Ag⁺ to Ag⁰, and producing Ag-GA-g-CSNPs (hybrid NPs I). Also, GA was grafted into CS-AgNPs, to form GA-g-CS AgNPs (hybrid NPs II). Although there were previous attempts to graft GA into CS, this is first time to graft GA into CS-AgNPs. The study aimed to enhance biocompatibility, antibacterial and antioxidant properties of CS-AgNPs via grafted GA. Grafting GA into CS-AgNPs was confirmed by UV-Vis, DLS, DSC/TGA, XRD, EDX and FTIR. The morphology and size of NPs were studied by TEM and SEM. The decrease of ζ-potential from +50 mV in CS-Ag NPs to +33 and + 29 mV, in the presented 2 nanoforms hybrid NPs I and II, respectively, is an indication for the successful GA graft. Among all samples, hybrid NPs II showed lower toxicity, higher antioxidant and antibacterial activity. The obtained results revealed that grafting GA to CS-AgNPs, as a new method to combine Ag, CS and GA in a uniparticulate structure, is a unique process which may deserve a more future consideration.

Pterostilbene loaded poly(vinyl alcohol)-gelatin cryogels as potential bioactive wound dressing material

Cryogels are support materials which are good at mimicking extracellular matrix due to their excellent hydrophilicity, biocompatibility, and macroporous structure, thus they are useful in facilitating cell activities during healing process. In this study, polyvinyl alcohol-gelatin (PVA-Gel) based cryogel membranes loaded with pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene; PTS) (PVA-Gel/PTS) was synthesized as wound dressing materials. PVA-Gel and PVA-Gel/PTS were synthesized with the polymerization yields of 96% ± 0.23% and 98% ± 0.18%, respectively, and characterized by swelling tests, Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) analysis. The swelling ratios were calculated as 98.6% ± 4.93% and 102% ± 5.1%, macroporosities were determined as 85% ± 2.13% and 88% ± 2.2%, for PVA-Gel and PVA-Gel/PTS, respectively. It was determined that PVA-Gel and PVA-Gel/PTS have 17 m² /g ± 0.76 m² /g and 20 m² /g ± 0.92 m² /g surface areas, respectively. SEM studies were demonstrated that they have ~100 μm pore sizes. According to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), trypan blue exclusion and live-dead assay results, it was observed that cell proliferation, cell number and cell viability were higher in PVA-Gel/PTS cryogel at 24, 48, and 72 h compared to PVA-Gel. A strong and transparent fluorescent light intensity was observed indicating higher cell population in PVA-Gel/PTS in comparison with PVA-Gel, according to 4',6-diamidino-2-phenylindole (DAPI) staining. SEM, F-Actin, Giemsa staining and inverted-phase microscope image of fibroblasts in PVA-Gel/PTS cryogels revealed that dense fibroblast proliferation and spindle-shaped morphology of cells were preserved. Moreover, DNA agarose gel data demonstrated that PVA-Gel/PTS cryogels had no effect on DNA integrity. Consequently, produced PVA-Gel/PTS cryogel can be used as wound dressing material to promote wound therapies, inducing cell viability and proliferation.

Chitosan/Phenolic Compounds Scaffolds for Connective Tissue Regeneration

Chitosan-based scaffolds modified by gallic acid, ferulic acid, and tannic acid were fabricated. The aim of the experiment was to compare the compatibility of scaffolds based on chitosan with gallic acid, ferulic acid, or tannic acid using the in vivo method. For this purpose, materials were implanted into rabbits in the middle of the latissimus dorsi muscle length. A scaffold based on unmodified chitosan was implanted by the same method as a control. Moreover, the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) spectra and scanning electron microscope (SEM) observations were made to study the interactions between chitosan and phenolic acids. Additionally, antioxidant properties and blood compatibility were investigated. The results showed that all studied materials were safe and non-toxic. However, chitosan scaffolds modified by gallic acid and tannic acid were resorbed faster and, as a result, tissues were organized faster than those modified by ferulic acid or unmodified.

Bombesin Peptide Conjugated Water-Soluble Chitosan Gallate-A New Nanopharmaceutical Architecture for the Rapid One-Pot Synthesis of Prostate Tumor Targeted Gold Nanoparticles

PURPOSE

We report herein bombesin peptide conjugated water-soluble chitosan gallate as a template for rapid one-pot synthesis of gold nanoparticles (AuNPs) with capabilities to target receptors on prostate cancer cells.

METHODS

Water-soluble chitosan (WCS), anchored with gallic acid (GA) and LyslLys3 (1,4,7,10-tetraazacyclo dodecane-1,4,7,10-tetraacetic acid) bombesin 1-14 (DBBN) peptide, provides a tumor targeting nanomedicine agent. WCS nanoplatforms provide attractive strategies with built-in capabilities to reduce gold (III) to gold nanoparticles with stabilizing and tumor-targeting capabilities. WCS-GA-DBBN encapsulation around gold nanoparticles affords optimum in vitro stability.

RESULTS

The DBBN content in the WCS-GA-DBBN sample was ~27%w/w. The antioxidant activities of WCS-GA and WCS-GA-DBBN nanocolloids were enhanced by 12 times as compared to the nascent WCS. AuNPs with a desirable hydrodynamic diameter range of 40-60 nm have been efficiently synthesized using WCS-GA and WCS-GA-DBBN platforms. The AuNPs were stable over 4 days after preparation and ~3 days after subjecting to all relevant biological fluids. The AuNPs capped with WCS-GA-DBBN peptide exhibited superior cellular internalization into prostate tumor (PC-3) cells with evidence of receptor mediated endocytosis.

CONCLUSION

The AuNPs capped with WCS-GA-DBBN exhibited selective affinity toward prostate cancer cells. AuNPs conjugated with WCS-GA-DBBN serve as a new generation of theranostic agents for treating various neoplastic diseases, thus opening-up new applications in oncology.

Chemotherapeutic and chemopreventive potentials of ρ-coumaric acid - Squid chitosan nanogel loaded with Syzygium aromaticum essential oil

One of the most important trends in chemotherapy is the development of green chemotropic drugs with maximal activity and minimal side effects. The nanoencapsulation of phytochemical oils with natural polymers has been documented as a promising approach to producing nanodrugs with sustainable bioactivity and prolonged stability. In this context, Syzygium aromaticum essential oil (SAEO) and ultrasound-assisted deacetylated chitosan (UCS₃) were successfully extracted from clove buds and squid pens, respectively. Grafting of UCS₃ by ρ-coumaric acid (ρCA) has been performed to fabricate the ρCACS nanogel which was used for nanoencapsulation of SAEO to yield SAEO-loaded nanogel (ρCACS@SAEO). The findings of spectral, thermal, and morphological analyses have confirmed the success of the formation of new materials and SAEO encapsulation, as well. Based on the findings of the in vitro antimicrobial, antioxidant, and anticancer studies, the nanoencapsulation of SAEO by ρCACS has significantly boosted its chemotherapeutic effects, compared to unencapsulated oil. Therefore, ρCACS@SAEO nanogel could be considered as a multifunctional chemotherapeutic/chemopreventive agent for prevention or therapy of pathologies induced by oxidative stress, microbial infection, and breast and skin cancer.

Surface modification of neurotrophin-3 loaded PCL/chitosan nanofiber/net by alginate hydrogel microlayer for enhanced biocompatibility in neural tissue engineering

This study prepared a novel three-dimensional nanocomposite scaffold by the surface modification of PCL/chitosan nanofiber/net with alginate hydrogel microlayer, hoping to have the privilege of both nanofibers and hydrogels simultaneously. Bead free randomly oriented nanofiber/net (NFN) structure composed of chitosan and polycaprolactone (PCL) was fabricated by electrospinning method. The low surface roughness, good hydrophilicity, and high porosity were obtained from the NFN structure. Then, the PCL/chitosan nanofiber/net was coated with a microlayer of alginate containing neurotrophin-3 (NT-3) and conjunctiva mesenchymal stem cells (CJMSCs) as a new stem cell source. According to the cross-sectional FESEM, the scaffold shows a two-layer structure with interconnected pores in the range of 20 μm diameter. The finding revealed that the surface modification of nanofiber/net by alginate hydrogel microlayer caused lower inflammatory response and higher proliferation of CJMSCs than the unmodified scaffold. The initial burst release of NT-3 was 69% in 3 days which followed by a sustained release up to 21 days. The RT-PCR analysis showed that the expression of Nestin, MAP-2, and β-tubulin III genes were increased 6, 5.4, and 8.8-fold, respectively. The results revealed that the surface-modified biomimetic scaffold possesses enhanced biocompatibility and could successfully differentiate CJMSCs to the neuron-like cells.

Plant based cross-linkers for tissue engineering applications

Utility of plant-based materials in tissue engineering has exponentially increased over the years. Recent efforts in this area have been focused on substituting synthetic cross-linkers with natural ones derived from biological sources. These cross-linkers are essentially derived from the vegetative components of plants therefore suitably categorised as 'green' and renewable materials. Utilization of plant based cross-linkers in scaffolds and hydrogels offers several advantages compared to the synthetic ones. Natural compounds, like ferulic acid and genipin, when incorporated into scaffolds can promote cellular proliferation and growth, by regulation of growth factors. They participate in crucial activities, thus providing impetus for cell growth, function, differentiation and angiogenesis. Several natural compounds inherently possess anti-microbial, antioxidant and anti-inflammatory effects, which enhance the inherent characteristics of the scaffolds. Versatility of natural cross-linkers can be exploited for diverse applications. Integrating such potent molecules can enable the scaffold to display relevant characteristics for each function. This review article focuses on the recent developments with plant based cross-linkers that are employed for scaffold synthesis and their applications, which may be explored to synthesize scaffolds suitable for diverse biomedical applications.

Graphene Oxide/Copper Nanoderivatives-Modified Chitosan/Hyaluronic Acid Dressings for Facilitating Wound Healing in Infected Full-Thickness Skin Defects

PURPOSE

Wound healing, especially of infected wounds, remains a clinical challenge in plastic surgery. This study aimed to manufacture a novel and multifunctional wound dressing by combining graphene oxide/copper nanocomposites (GO/Cu) with chitosan/hyaluronic acid, providing significant opportunities for the therapy of wound repair in wounds with a high risk of bacterial infection.

METHODS

In this study, GO/Cu-decorated chitosan/hyaluronic acid dressings (C/H/GO/Cu) were prepared using sodium trimetaphosphate (STMP) crosslinking and the vacuum freeze-drying method, and chitosan/hyaluronic acid dressings (C/H) and GO-incorporated chitosan/hyaluronic acid dressings (C/H/GO) served as controls. The surface characterization, in vitro degradation under various pH values, antimicrobial potential, cytocompatibility and in vivo therapeutic efficacy in a bacteria-infected full-thickness skin defect model were systematically evaluated.

RESULTS

Our experimental results indicated that the acidic environment facilitated the release of copper (CuNPs and Cu2+) from the dressings, and prepared C/H/GO/Cu dressings exhibited significant in vitro antimicrobial activities against the two tested bacterial strains (ATCC35984 and ATCC25923). All three dressings showed satisfactory cytocompatibility with mouse fibroblasts (NIH/3T3-L1). Moreover, remarkably accelerated wound healing was found in the C/H/GO/Cu group, with controlled inflammatory infiltration and improved angiogenesis in granulation tissues. In addition, no pathological damage was noted in the tissue structures of the tested organs (heart, lung, liver and kidney) in any of the four groups.

CONCLUSION

Collectively, GO/Cu-incorporated chitosan/hyaluronic acid dressings suggested a synergistic antimicrobial efficacy and acceptable biocompatibility both in vitro and in vivo, as well as a significantly accelerated healing process of bacteria-infected wounds. Thus, the multifunctional C/H/GO/Cu composite is expected to be a potential alternative for wound dressings, especially for the management of intractable wounds caused by bacterial infection.

Glycerylphytate as an ionic crosslinker for 3D printing of multi-layered scaffolds with improved shape fidelity and biological features

The fabrication of intricate and long-term stable 3D polymeric scaffolds by a 3D printing technique is still a challenge. In the biomedical field, hydrogel materials are very frequently used because of their excellent biocompatibility and biodegradability, however the improvement of their processability and mechanical properties is still required. This paper reports the fabrication of dual crosslinked 3D scaffolds using a low concentrated (<10 wt%) ink of gelatin methacryloyl (GelMA)/chitosan and a novel crosslinking agent, glycerylphytate (G1Phy) to overcome the current limitations in the 3D printing field using hydrogels. The applied methodology consisted of a first ultraviolet light (UV) photopolymerization followed by a post-printing ionic crosslinking treatment with G1Phy. This crosslinker provides a robust framework and avoids the necessity of neutralization with strong bases. The blend ink showed shear-thinning behavior and excellent printability in the form of a straight and homogeneous filament. UV curing was undertaken simultaneously to 3D deposition, which enhanced precision and shape fidelity (resolution ≈150 μm), and prevented the collapse of the subsequent printed layers (up to 28 layers). In the second step, the novel G1Phy ionic crosslinker agent provided swelling and long term stability properties to the 3D scaffolds. The multi-layered printed scaffolds were mechanically stable under physiological conditions for at least one month. Preliminary in vitro assays using L929 fibroblasts showed very promising results in terms of adhesion, spreading, and proliferation in comparison to other phosphate-based traditional crosslinkers (i.e. TPP). We envision that the proposed combination of the blend ink and 3D printing approach can have widespread applications in the regeneration of soft tissues.

Synthesis, Characterization, and Histological Evaluation of Chitosan-Ruta Graveolens Essential Oil Films

The development of new biocompatible materials for application in the replacement of deteriorated tissues (due to accidents and diseases) has gained a lot of attention due to the high demand around the world. Tissue engineering offers multiple options from biocompatible materials with easy resorption. Chitosan (CS) is a biopolymer derived from chitin, the second most abundant polysaccharide in nature, which has been highly used for cell regeneration applications. In this work, CS films and Ruta graveolens essential oil (RGEO) were incorporated to obtain porous and resorbable materials, which did not generate allergic reactions. An oil-free formulation (F1: CS) and three different formulations containing R. graveolens essential oil were prepared (F2: CS-RGEO 0.5%; F3: CS+RGEO 1.0%; and F4: CS+RGEO 1.5%) to evaluate the effect of the RGEO incorporation in the mechanical and thermal stability of the films. Infrared spectroscopy (FTIR) analyses demonstrated the presence of RGEO. In contrast, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis showed that the crystalline structure and percentage of CS were slightly affected by the RGEO incorporation. Interesting saturation phenomena were observed for mechanical and water permeability tests when RGEO was incorporated at higher than 0.5% (v/v). The results of subdermal implantation after 30 days in Wistar rats showed that increasing the amount of RGEO resulted in greater resorption of the material, but also more significant inflammation of the tissue surrounding the materials. On the other hand, the thermal analysis showed that the RGEO incorporation almost did not affect thermal degradation. However, mechanical properties demonstrated an understandable loss of tensile strength and Young’s modulus for F3 and F4. However, given the volatility of the RGEO, it was possible to generate a slightly porous structure, as can be seen in the microstructure analysis of the surface and the cross-section of the films. The cytotoxicity analysis of the CS+RGEO compositions by the hemolysis technique agreed with in vivo results of the low toxicity observed. All these results demonstrate that films including crude essential oil have great application potential in the biomedical field.

Reduced graphene oxide-loaded nanocomposite scaffolds for enhancing angiogenesis in tissue engineering applications

Tissue engineering combines cells, scaffolds and signalling molecules to synthesize tissues in vitro. However, the lack of a functioning vascular network severely limits the effective size of a tissue-engineered construct. In this work, we have assessed the potential of reduced graphene oxide (rGO), a non-protein pro-angiogenic moiety, for enhancing angiogenesis in tissue engineering applications. Polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) scaffolds loaded with different concentrations of rGO nanoparticles were synthesized via lyophilization. Characterization of these scaffolds showed that the rGO-loaded scaffolds retained the thermal and physical properties (swelling, porosity and in vitro biodegradation) of pure PVA/CMC scaffolds. In vitro cytotoxicity studies, using three different cell lines, confirmed that the scaffolds are biocompatible. The scaffolds containing 0.005 and 0.0075% rGO enhanced the proliferation of endothelial cells (EA.hy926) in vitro. In vivo studies using the chick chorioallantoic membrane model showed that the presence of rGO in the PVA/CMC scaffolds significantly enhanced angiogenesis and arteriogenesis.

An investigation of konjac glucomannan-keratin hydrogel scaffold loaded with Avena sativa extracts for diabetic wound healing

We have developed a novel hydrogel composed of konjac glucomannan (KGM), human hair proteins (KER), and an ethanolic extract of Avena sativa (OAT) and evaluated its potential as a dressing material for diabetic wounds. KGM is an excellent biocompatible gelling agent that stimulates fibroblast proliferation and immunomodulation. Human hair proteins (KER) are biocompatible, biodegradable, and possess abundant cell adhesion sites. KER also promotes fibroblast attachment and proliferation, keratinocyte migration, and collagen expression, which can accelerate wound healing. OAT consists of oat β-glucans and several anti-inflammatory and antioxidant moieties that can reduce prolonged inflammation in chronic wounds. SEM images confirm the highly porous architecture of the scaffolds. When immersed in PBS, KGM+KER+OAT hydrogels absorb 7.5 times their dry weight. These hydrogels display a measured rate of degradation in lysozyme. KGM+KER+OAT hydrogels showed no significant cytotoxicity against NIH/3T3 fibroblasts. DAPI and SEM images obtained after 48h of cell culture illustrate the attachment and infiltration of fibroblasts. In vivo studies performed using a diabetic rat excision wound model showed that KGM+KER+OAT hydrogels significantly accelerated wound healing compared to the control and the KGM+KER hydrogels.

Development of reduced graphene oxide (rGO)-isabgol nanocomposite dressings for enhanced vascularization and accelerated wound healing in normal and diabetic rats

Treatment of chronic non-healing wounds in diabetes is still a major clinical challenge. Here, we have developed reduced graphene oxide (rGO) loaded isabgol nanocomposite scaffolds (Isab + rGO) to treat normal and diabetic wounds. rGO was synthesized by rapid reduction of graphene oxide (GO) under focused solar radiation. Then, rGO was uniformly dispersed into isabgol solution to prepare Isab + rGO nanocomposite scaffolds. These scaffolds were characterized using various physiochemical techniques. Isab + rGO nanocomposite scaffolds showed suitable cell viability, proliferation, and attachment. In vivo experiments were performed using Wistar rats to study the wound healing efficacy of these scaffolds in normal and diabetic rats. Results revealed that rGO stimulated collagen synthesis, collagen crosslinking, wound contraction, and reduced the wound re-epithelialization time significantly compared to control. Histology and immunohistochemistry analyses showed that Isab + rGO scaffold treatment enhanced angiogenesis, collagen synthesis, and deposition in treated wounds. Isab + rGO scaffold treatment also played a major role in shortening the inflammation phase and recruiting macrophages to enhance the early phase of wound healing. Overall, this investigation showed that Isab + rGO scaffold dressing could significantly accelerate the healing of normal and diabetic wounds.

Methacrylated gelatin/hyaluronan-based hydrogels for soft tissue engineering

In vitro–generated soft tissue could provide alternate therapies for soft tissue defects. The aim of this study was to evaluate methacrylated gelatin/hyaluronan as scaffolds for soft tissue engineering and their interaction with human adipose–derived stem cells (hASCs). ASCs were incorporated into methacrylated gelatin/hyaluronan hydrogels. The gels were photocrosslinked with a lithium phenyl-2,4,6-trimethylbenzoylphosphinate photoinitiator and analyzed for cell viability and adipogenic differentiation of ASCs over a period of 30 days. Additionally, an angiogenesis assay was performed to assess their angiogenic potential. After 24 h, ASCs showed increased viability on composite hydrogels. These results were consistent over 21 days of culture. By induction of adipogenic differentiation, the mature adipocytes were observed after 7 days of culture, their number significantly increased until day 28 as well as expression of fatty acid binding protein 4 and adiponectin. Our scaffolds are promising as building blocks for adipose tissue engineering and allowed long viability, proliferation, and differentiation of ASCs.

Accelerated Healing of Diabetic Wounds Treated with L-Glutamic acid Loaded Hydrogels Through Enhanced Collagen Deposition and Angiogenesis: An In Vivo Study

We have developed L-glutamic acid (LG) loaded chitosan (CS) hydrogels to treat diabetic wounds. Although literature reports wound healing effects of poly(glutamic acid)-based materials, there are no studies on the potential of L-glutamic acid in treating diabetic wounds. As LG is a direct precursor for proline synthesis, which is crucial for collagen synthesis, we have prepared CS + LG hydrogels to accelerate diabetic wound healing. Physiochemical properties of the CS + LG hydrogels showed good swelling, thermal stability, smooth surface morphology, and controlled biodegradation. The addition of LG to CS hydrogels did not alter their biocompatibility significantly. CS + LG hydrogel treatment showed rapid wound contraction compared to control and chitosan hydrogel. Period of epithelialization is significantly reduced in CS + LG hydrogel treated wounds (16 days) compared to CS hydrogel (20 days), and control (26 days). Collagen synthesis and crosslinking are also significantly improved in CS + LG hydrogel treated diabetic rats. Histopathology and immunohistochemistry results revealed that the CS + LG hydrogel dressing accelerated vascularization and macrophage recruitment to enhance diabetic wound healing. These results demonstrate that incorporation of LG can improve collagen deposition, and vascularization, and aid in faster tissue regeneration. Therefore, CS + LG hydrogels could be an effective wound dressing used to treat diabetic wounds.

Highly defined 3D printed chitosan scaffolds featuring improved cell growth

The augmented demand for medical devices devoted to tissue regeneration and possessing a controlled micro-architecture means there is a need for industrial scale-up in the production of hydrogels. A new 3D printing technique was applied to the automation of a freeze-gelation method for the preparation of chitosan scaffolds with controlled porosity. For this aim, a dedicated 3D printer was built in-house: a preliminary effort has been necessary to explore the printing parameter space to optimize the printing results in terms of geometry, tolerances and mechanical properties of the product. Analysed parameters included viscosity of the starting chitosan solution, which was measured with a Brookfield viscometer, and temperature of deposition, which was determined by filming the process with a cryocooled sensor thermal camera. Optimized parameters were applied to the production of scaffolds from solutions of chitosan alone or with the addition of raffinose as a viscosity modifier. Resulting hydrogels were characterized in terms of morphology and porosity. In vitro cell culture studies comparing 3D printed scaffolds with their homologous produced by solution casting evidenced an improvement in biocompatibility deriving from the production technique as well as from the solid state modification of chitosan stemming from the addition of the viscosity modifier.

Isabgol–silk fibroin 3D composite scaffolds as an effective dermal substitute for cutaneous wound healing in rats

Psyllium husk based silk 3D scaffolds were developed via freeze drying method without adding any bioactive substances to enhance tissue repair during cutaneous wound healing in rats.