Production of chitosan PVA PCL hydrogels to bind heparin and induce angiogenesis

Development of Mucoadhesive Electrospun Scaffolds for Intravaginal Delivery of Lactobacilli spp., a Tenside, and Metronidazole for the Management of Bacterial Vaginosis

Bacterial vaginosis (BV) is an infection of the vagina associated with thriving anaerobes, such as Gardnerella vaginitis and other associated pathogens. These pathogens form a biofilm responsible for the recurrence of infection after antibiotic therapy. The aim of this study was to develop a novel mucoadhesive polyvinyl alcohol and polycaprolactone electrospun nanofibrous scaffolds for vaginal delivery, incorporating metronidazole, a tenside, and Lactobacilli. This approach to drug delivery sought to combine an antibiotic for bacterial clearance, a tenside biofilm disruptor, and a lactic acid producer to restore healthy vaginal flora and prevent the recurrence of bacterial vaginosis. F7 and F8 had the least ductility at 29.25% and 28.39%, respectively, and this could be attributed to the clustering of particles that prevented the mobility of the crazes. F2 had the highest at 93.83% due to the addition of a surfactant that increased the affinity of the components. The scaffolds exhibited mucoadhesion between 31.54 ± 0.83% and 57.86 ± 0.95%, where an increased sodium cocoamphoacetate concentration led to increased mucoadhesion. F6 showed the highest mucoadhesion at 57.86 ± 0.95%, as compared to 42.67 ± 1.22% and 50.89 ± 1.01% for the F8 and F7 scaffolds, respectively. The release of metronidazole via a non-Fickian diffusion-release mechanism indicated both swelling and diffusion. The anomalous transport within the drug-release profile pointed to a drug-discharge mechanism that combined both diffusion and erosion. The viability studies showed a growth of Lactobacilli fermentum in both the polymer blend and the nanofiber formulation that was retained post-storage at 25 °C for 30 days. The developed electrospun scaffolds for the intravaginal delivery of Lactobacilli spp., along with a tenside and metronidazole for the management of bacterial vaginosis, provide a novel tool for the treatment and management of recurrent vaginal infection.

Phenol-Grafted Alginate Sulfate Hydrogel as an Injectable FGF-2 Carrier

In the field of tissue engineering, fibroblast growth factor-2 (FGF-2) effectively regenerates damaged tissue and restores its biological function. However, FGF-2 readily diffuses and degrades under physiological conditions. Therefore, methods for the sustained and localized delivery of FGF-2 are needed. Drug delivery systems using hydrogels as carriers have attracted significant interest. Injectable hydrogels with an affinity for FGF-2 are candidates for FGF-2 delivery systems. In this study, we fabricated a hydrogel from phenol-grafted alginate sulfate (AlgS-Ph) and investigated its application to the delivery of FGF-2. The hydrogel was prepared under mild conditions via horseradish peroxidase (HRP)-mediated cross-linking. Surface plasmon resonance (SPR) measurements show that the AlgS-Ph hydrogel has an affinity for FGF-2 in accordance with its degree of sulfation. Conditions for the preparation of the AlgS-Ph hydrogel, including HRP and H₂O₂ concentrations, are optimized so that the hydrogel can be used as an injectable drug carrier. The hydrogel shows no cytotoxicity when using 10T1/2 cells as a model cell line. The angiogenesis assay shows that FGF-2 released from the AlgS-Ph hydrogel promotes the formation of blood vessels. These results indicate that the AlgS-Ph hydrogel is a suitable candidate for the FGF-2 carrier.

A study of the comparative effect of cerium oxide and cerium peroxide on stimulation of angiogenesis: Design and synthesis of pro-angiogenic chitosan/collagen hydrogels

Poor angiogenesis at injury site is a major problem in chronic wounds, which could lead to limbs amputation in adverse cases. To overcome this issue, several efforts have made in literature and by our group as well to develop pro-angiogenic agents. For this purpose, metal oxides due to their oxidative potential have been studied and found very attractive agents. Cerium oxides are proven to be non-toxic and their biological studies have already proved their importance in preventing chronic inflammation, and neurological diseases among several others by modulating the intracellular reactive oxygen species. In current study, we report the synthesis and neovascularization activity of cerium oxide and cerium peroxide nanoparticles when loaded into chitosan and collagen hydrogel. The hydrogels were characterized by FTIR, SEM and XRD. The pro-angiogenic behavior of these hydrogels was studied by in-vivo CAM assay. It was found that cerium peroxide loaded material showed significantly increase in angiogenesis as compared to cerium oxide loaded materials. It was demonstrated that cerium peroxide hydrogels enhanced the angiogenic capability in CAM assay as compared to cerium oxide and hence holds good potential for chronic ulcer and burn wounds healing.

Heparin-Loaded Alginate Hydrogels: Characterization and Molecular Mechanisms of Their Angiogenic and Anti-Microbial Potential

Background: Chronic wounds continue to be a global concern that demands substantial resources from the healthcare system. The process of cutaneous wound healing is complex, involving inflammation, blood clotting, angiogenesis, migration and remodeling. In the present study, commercially available alginate wound dressings were loaded with heparin. The purpose of the study was to enhance the angiogenic potential of alginate wound dressings and analyze the antibacterial activity, biocompatibility and other relevant properties. We also aimed to conduct some molecular and gene expression studies to elaborate on the mechanisms through which heparin induces angiogenesis. Methods: The physical properties of the hydrogels were evaluated by Fourier transform infrared spectroscopy (FTIR). Swelling ability was measured by soaking hydrogels in the Phosphate buffer at 37 °C, and cell studies were conducted to evaluate the cytotoxicity and biocompatibility of hydrogels in NIH3T3 (fibroblasts). Real-time PCR was conducted to check the molecular mechanisms of heparin/alginate-induced angiogenesis. The physical properties of the hydrogels were evaluated by Fourier transform infrared spectroscopy (FTIR). Results: FTIR confirmed the formation of heparin-loaded alginate wound dressing and the compatibility of both heparin and alginate. Among all, 10 µg/mL concentration of heparin showed the best antibacterial activity against E. coli. The swelling was considerably increased up to 1500% within 1 h. Alamar Blue assay revealed no cytotoxic effect on NIH3T3. Heparin showed good anti-microbial properties and inhibited the growth of E. coli in zones with a diameter of 18 mm. The expression analysis suggested that heparin probably exerts its pro-angiogenetic effect through VEGF and cPGE. Conclusions: We report that heparin-loaded alginate dressings are not cytotoxic and offer increased angiogenic and anti-bacterial potential. The angiogenesis is apparently taken through the VEGF pathway.

Bioactive Composite for Orbital Floor Repair and Regeneration

In the maxillofacial area, specifically the orbital floor, injuries can cause bone deformities in the head and face that are difficult to repair or regenerate. Treatment methodologies include use of polymers, metal, ceramics on their own and in combinations mainly for repair purposes, but little attention has been paid to identify suitable materials for orbital floor regeneration. Polyurethane (PU) and hydroxyapatite (HA) micro- or nano- sized with different percentages (25%, 40% & 60%) were used to fabricate bioactive tissue engineering (TE) scaffolds using solvent casting and particulate leaching methods. Mechanical and physical characterisation of TE scaffolds was investigated by tensile tests and SEM respectively. Chemical and structural properties of PU and PU/HA scaffolds were evaluated by infrared (IR) spectroscopy and Surface properties of the bioactive scaffold were analysed using attenuated total reflectance (ATR) sampling accessory coupled with IR. Cell viability, collagen formed, VEGF protein amount and vascularisation of bioactive TE scaffold were studied. IR characterisation confirmed the integration of HA in composite scaffolds, while ATR confirmed the significant amount of HA present at the top surface of the scaffold, which was a primary objective. The SEM images confirmed the pores' interconnectivity. Increasing the content of HA up to 40% led to an improvement in mechanical properties, and the incorporation of nano-HA was more promising than that of micro-HA. Cell viability assays (using MG63) confirmed biocompatibility and CAM assays confirmed vascularization, demonstrating that HA enhances vascularization. These properties make the resulting biomaterials very useful for orbital floor repair and regeneration.

Synthesis, Chemical and Biomedical Aspects of the Use of Sulfated Chitosan

This work is devoted to the chemical synthesis of sulfated chitosan and its experimental verification in an animal model of early atherosclerosis. The method of chitosan quaternization with sulfate-containing ingredients resulted in a product with a high content of sulfate groups. Implantation of this product into the fascial-muscular sheath of the main limb artery along the leg and thigh in rabbits led to the extraction of cholesterol from the subintimal region. Simplified methods for the chemical synthesis of quaternized sulfated chitosan and the use of these products in a model of experimental atherosclerosis made it possible to perform a comparative morphological analysis of the vascular walls of the experimental and control limbs under conditions of a long-term high-cholesterol diet. The sulfated chitosan samples after implantation were shown to change the morphological pattern of the intimal and middle membranes of the experimental limb artery. The implantation led to the degradation of soft plaques within 30 days after surgical intervention, which significantly increased collateral blood flow. The implantation of sulfated chitosan into the local area of the atherosclerotic lesions in the artery can regulate the cholesterol content in the vascular wall and destroy soft plaques in the subintimal region.

Hydroxyapatite-Integrated, Heparin- and Glycerol-Functionalized Chitosan-Based Injectable Hydrogels with Improved Mechanical and Proangiogenic Performance

The investigation of natural bioactive injectable composites to induce angiogenesis during bone regeneration has been a part of recent minimally invasive regenerative medicine strategies. Our previous study involved the development of in situ-forming injectable composite hydrogels (Chitosan/Hydroxyapatite/Heparin) for bone regeneration. These hydrogels offered facile rheology, injectability, and gelation at 37 °C, as well as promising pro-angiogenic abilities. In the current study, these hydrogels were modified using glycerol as an additive and a pre-sterile production strategy to enhance their mechanical strength. These modifications allowed a further pH increment during neutralisation with maintained solution homogeneity. The synergetic effect of the pH increment and further hydrogen bonding due to the added glycerol improved the strength of the hydrogels substantially. SEM analyses showed highly cross-linked hydrogels (from high-pH solutions) with a hierarchical interlocking pore morphology. Hydrogel solutions showed more elastic flow properties and incipient gelation times decreased to just 2 to 3 min at 37 °C. Toluidine blue assay and SEM analyses showed that heparin formed a coating at the top layer of the hydrogels which contributed anionic bioactive surface features. The chick chorioallantoic membrane (CAM) assay confirmed significant enhancement of angiogenesis with chitosan-matrixed hydrogels comprising hydroxyapatite and small quantities of heparin (33 µg/mL) compared to basic chitosan hydrogels.

Design and development of thyroxine/heparin releasing affordable cotton dressings to treat chronic wounds

This research on a thyroxine/heparin-based cotton wound dressing tests angiogenic and wound healing ability of thyroxine/heparin in a chick chorionic allantoic membrane bioassay and in skin wounds in healthy rats. Commercially available cotton dressings were simply loaded with thyroxine/heparin solutions and coated with wax. Prior to undertaking the animal study, we assessed in vitro release of thyroxine/heparin from coated and uncoated cotton dressings. Both showed more than 85% release of drug over 14 days, though the lesser release was observed in wax-coated thyroxine/heparin dressing as compared to uncoated thyroxine/heparin dressing. Testing of angiogenesis through CAM assay proved good angiogenic potential of heparin and thyroxin, but the thyroxine found more angiogenic than heparin. In animal study, full-thickness skin wounds of 20 mm diameter showed good healing in both heparin and thyroxine-treated groups. But the most striking result was seen in the thyroxine-treated group where thyroxine showed significant difference with heparin-treated group and completely healed the wounds in 23 days. Thus, the study suggest that thyroxine possesses greater angiogenic and wound healing potential than heparin, and the use of thyroxine/heparin-loaded wax-coated cotton dressing could be a cost-effective option for the management of chronic wounds.

Angiogenic potential and wound healing efficacy of chitosan derived hydrogels at varied concentrations of APTES in chick and mouse models

Chitosan (Cs) based biomaterials seem to be indispensable for neovasculogenesis and angiogenesis that ensure accelerated wound healing. Cs/poly (vinyl alcohol) (PVA) bio-constructs were cross-linked and investigated with varying concentrations of aminopropyltriethoxysilane (APTES). This study comprised of three phases: fabrication of hydrogels, characterization, assessment of angiogenic potential along with toxico-pathological effects, wound healing efficacy in chick and mice, respectively. The hydrogels were characterized by FTIR, SEM and TGA and the swelling response was examined in different solvents. The hydrogels swelling ratio was decreased with increasing amount of APTES, showed the highest swelling at acidic and basic pH while low swelling at neutral pH. Chorioallantoic membranes (CAM) assay was performed to study in-vivo angiogenesis, toxicological, morphological, biochemical and histological analyses in developing chicks. The results showed remarkably improved angiogenesis with little deviations in morphological, histological features and liver enzymes of chick embryos at higher concentrations of APTES. Besides, full thickness wounds were excised on mice dorsolateral skin to assess the wound healing. The rate of wound size reduction was significantly higher after topical application of hydrogels with elevated levels of crosslinker. Hence, the hydrogels showed enhanced angiogenesis, accelerated wound healing with little or no observable in-vivo toxicity.

Developing sulfur-doped titanium oxide nanoparticles loaded chitosan/cellulose-based proangiogenic dressings for chronic ulcer and burn wounds healing

Development of biomaterials supporting angiogenesis are highly desired in medical applications. In current work, chitosan and cellulose were cross-linked by using triethyl orthoformate and loaded with sulfur-doped titanium oxide nanoparticles. A readily available and inexpensive titanium oxide was added as a potential proangiogenic agent based on our group findings and other reports on metal oxide nanoparticles activity to stimulate angiogenesis. A simple freeze gelation method led to the development of flexible, foldable, and porous membranes. To investigate the chemical characteristics of the synthesized membranes, Fourier-transform infrared spectroscopy was used. Scanning electron microscopy equipped with energy-dispersive X-ray microanalysis was employed for surface morphological investigations. The cross-linked membranes showed higher degree of swelling capacity compared to the same material with titania-loaded nanoparticles in vitro. The synthesized materials showed higher degree of degradation in H₂ O₂ as compared to phosphate-buffered saline and lysozyme. Chorioallantoic membrane assay was done to investigate the angiogenic potential. Titanium oxide nanoparticles loaded membranes (CLHTS-5 wt%) exhibited the best degree of angiogenesis in comparison to the other tested materials. In CLHTS-5 wt% experimental group, a good level of attachment and ingrowth of several blood vessels was observed. Interestingly, the same tested group (CLHTS-5 wt%) had shown the increasing trend of cellular metabolic rate of the seeded cells from Day 0 to Day 7 in vitro. These findings were further confirmed by the decline in lactate dehydrogenase enzyme release which was monitored until 72 h, indicating the promising ability of this biomaterial in wound healing applications.

Developing Wound Dressings Using 2-deoxy-D-Ribose to Induce Angiogenesis as a Backdoor Route for Stimulating the Production of Vascular Endothelial Growth Factor

2-deoxy-D-Ribose (2dDR) was first identified in 1930 in the structure of DNA and discovered as a degradation product of it later when the enzyme thymidine phosphorylase breaks down thymidine into thymine. In 2017, our research group explored the development of wound dressings based on the delivery of this sugar to induce angiogenesis in chronic wounds. In this review, we will survey the small volume of conflicting literature on this and related sugars, some of which are reported to be anti-angiogenic. We review the evidence of 2dDR having the ability to stimulate a range of pro-angiogenic activities in vitro and in a chick pro-angiogenic bioassay and to stimulate new blood vessel formation and wound healing in normal and diabetic rat models. The biological actions of 2dDR were found to be 80 to 100% as effective as VEGF in addition to upregulating the production of VEGF. We then demonstrated the uptake and delivery of the sugar from a range of experimental and commercial dressings. In conclusion, its pro-angiogenic properties combined with its improved stability on storage compared to VEGF, its low cost, and ease of incorporation into a range of established wound dressings make 2dDR an attractive alternative to VEGF for wound dressing development.

Marine Polysaccharides for Wound Dressings Application: An Overview

Wound dressings have become a crucial treatment for wound healing due to their convenience, low cost, and prolonged wound management. As cutting-edge biomaterials, marine polysaccharides are divided from most marine organisms. It possesses various bioactivities, which allowing them to be processed into various forms of wound dressings. Therefore, a comprehensive understanding of the application of marine polysaccharides in wound dressings is particularly important for the studies of wound therapy. In this review, we first introduce the wound healing process and describe the characteristics of modern commonly used dressings. Then, the properties of various marine polysaccharides and their application in wound dressing development are outlined. Finally, strategies for developing and enhancing marine polysaccharide wound dressings are described, and an outlook of these dressings is given. The diverse bioactivities of marine polysaccharides including antibacterial, anti-inflammatory, haemostatic properties, etc., providing excellent wound management and accelerate wound healing. Meanwhile, these biomaterials have higher biocompatibility and biodegradability compared to synthetic ones. On the other hand, marine polysaccharides can be combined with copolymers and active substances to prepare various forms of dressings. Among them, emerging types of dressings such as nanofibers, smart hydrogels and injectable hydrogels are at the research frontier of their development. Therefore, marine polysaccharides are essential materials in wound dressings fabrication and have a promising future.

Sustainable Development of Chitosan/Calotropis procera-Based Hydrogels to Stimulate Formation of Granulation Tissue and Angiogenesis in Wound Healing Applications

The formation of new scaffolds to enhance healing magnitude is necessarily required in biomedical applications. Granulation tissue formation is a crucial stage of wound healing in which granulation tissue grows on the surface of a wound by the formation of connective tissue and blood vessels. In the present study, porous hydrogels were synthesized using chitosan incorporating latex of the Calotropis procera plant by using a freeze-thaw cycle to stimulate the formation of granulation tissue and angiogenesis in wound healing applications. Structural analysis through Fourier transform infrared (FTIR) spectroscopy confirmed the interaction between chitosan and Calotropis procera. Latex extract containing hydrogel showed slightly higher absorption than the control during water absorption analysis. Thermogravimetric analysis showed high thermal stability of the 60:40 combination of chitosan (CS) and Calotropis procera as compared to all other treatments and controls. A fabricated scaffold application on a chick chorioallantoic membrane (CAM) showed that all hydrogels containing latex extract resulted in a significant formation of blood vessels and regeneration of cells. Overall, the formation of connective tissues and blood capillaries and healing magnitude decreased in ascending order of concentration of extract.

Biodegradable Food Packaging Materials and Prospects of the Fourth Industrial Revolution for Tomato Fruit and Product Handling

The environment and food safety are major areas of concern influencing the development of biodegradable packaging for partial replacement of petrochemical-based polymers. This review is aimed at updating the recent advances in biodegradable packaging material and the role of virtual technology and nanotechnology in the tomato supply chain. Some of the common biodegradable materials are gelatin, starch, chitosan, cellulose, and polylactic acid. The tensile strength, tear resistance, permeability, degradability, and solubility are some of the properties defining the selection and utilization of food packaging materials. Biodegradable films can be degraded in soil by microbial enzymatic actions and bioassimilation. Nanoparticles are incorporated into blended films to improve the performance of packaging materials. The prospects of the fourth industrial revolution can be realized with the use of virtual platforms such as sensor systems in authentification and traceability of food and packaging products. There is a research gap on the development of a hybrid sensor system unit that can integrate sampling headspace (SHS), detection unit, and data processing of big data for heterogeneous tomato-derived volatiles. Principal component analysis (PCA), linear discriminant analysis (LDA), and artificial neutral network (ANN) are some of the common mathematical models for data interpretation of sensor systems.

Chitosan based bioactive materials in tissue engineering applications-A review

In recent years, there have been increasingly rapid advances of using bioactive materials in tissue engineering applications. Bioactive materials constitute many different structures based upon ceramic, metallic or polymeric materials, and can elicit specific tissue responses. However, most of them are relatively brittle, stiff, and difficult to form into complex shapes. Hence, there has been a growing demand for preparing materials with tailored physical, biological, and mechanical properties, as well as predictable degradation behavior. Chitosan-based materials have been shown to be ideal bioactive materials due to their outstanding properties such as formability into different structures, and fabricability with a wide range of bioactive materials, in addition to their biocompatibility and biodegradability. This review highlights scientific findings concerning the use of innovative chitosan-based bioactive materials in the fields of tissue engineering, with an outlook into their future applications. It also covers latest developments in terms of constituents, fabrication technologies, structural, and bioactive properties of these materials that may represent an effective solution for tissue engineering materials, making them a realistic clinical alternative in the near future.

In-Situ Forming pH and Thermosensitive Injectable Hydrogels to Stimulate Angiogenesis: Potential Candidates for Fast Bone Regeneration Applications

Biomaterials that promote angiogenesis are required for repair and regeneration of bone. In-situ formed injectable hydrogels functionalised with bioactive agents, facilitating angiogenesis have high demand for bone regeneration. In this study, pH and thermosensitive hydrogels based on chitosan (CS) and hydroxyapatite (HA) composite materials loaded with heparin (Hep) were investigated for their pro-angiogenic potential. Hydrogel formulations with varying Hep concentrations were prepared by sol-gel technique for these homogeneous solutions were neutralised with sodium bicarbonate (NaHCO3) at 4 °C. Solutions (CS/HA/Hep) constituted hydrogels setting at 37 °C which was initiated from surface in 5-10 minutes. Hydrogels were characterised by performing injectability, gelation, rheology, morphology, chemical and biological analyses. Hydrogel solutions facilitated manual dropwise injection from 21 Gauge which is highly used for orthopaedic and dental administrations, and the maximum injection force measured through 19 G needle (17.191 ± 2.296N) was convenient for manual injections. Angiogenesis tests were performed by an ex-ovo chick chorioallantoic membrane (CAM) assay by applying injectable solutions on CAM, which produced in situ hydrogels. Hydrogels induced microvascularity in CAM assay this was confirmed by histology analyses. Hydrogels with lower concentration of Hep showed more efficiency in pro-angiogenic response. Thereof, novel injectable hydrogels inducing angiogenesis (CS/HA/Hep) are potential candidates for bone regeneration and drug delivery applications.

Thyroxine-loaded chitosan/carboxymethyl cellulose/hydroxyapatite hydrogels enhance angiogenesis in in-ovo experiments

Angiogenesis is one of the most important processes in repair and regeneration of many tissues and organs. Blood vessel formation also play a major role in repair of dental tissue(s) after ailments like periodontitis. Here we report the preparation of chitosan/carboxymethyl cellulose/hydroxyapatite based hydrogels, loaded with variable concentrations of thyroxin i.e., 0.1 μg/ml, 0.5 μg/ml and 1 μg/ml. Scanning electron microcopy images (SEM) showed all hydrogels were found to be porous and solution absorption study exhibited high swelling potential in aqueous media. FTIR spectra confirmed that the used materials did not change their chemical identity in synthesized hydrogels. The synthesized hydrogels demonstrated good bending, folding, rolling and stretching abilities. The hydrogels were tested in chick chorioallantoic membrane (CAM) assay to investigate their angiogenic potential. Hydrogel containing 0.1 μg/ml of thyroxine showed maximum neovascularization. For cytotoxicity analyses, preosteoblast cells (MC3T3-E1) were seeded on these hydrogels and materials were found to be non-toxic. These hydrogels with pro-angiogenic activity possess great potential to be used for periodontal regeneration.

Novel chitosan derivative based composite scaffolds with enhanced angiogenesis; potential candidates for healing chronic non-healing wounds

The success of wound healing depends upon the proper growth of vascular system in time in the damaged tissues. Poor blood supply to wounded tissues or tissue engineered grafts leads to the failure of wound healing or rejection of grafts. In present paper, we report the synthesis of novel organosoluble and pro-angiogenic chitosan derivative (CSD) by the reaction of chitosan with 1,3-dimethylbarbituric acid and triethylorthoformate (TEOF). The synthesized material was characterized by FTIR and ¹³C-NMR to confirm the incorporated functional groups and new covalent connectivities. Biodegradability of the synthesized chitosan derivative was tested in the presence of lysozyme and was found to be comparable with CS. The cytotoxicity and apoptosis effect of new derivative was determined against gastric adenocarcinoma (AGS) cells and was found to be non-toxic. The CSD was found to be soluble in majority of organic solvents. It was blended with polycaprolactone (PCL) to form composite scaffolds. From an ex ovo CAM assay, it was noted that CSD stimulated the angiogenesis.

Exploration of 2-deoxy-D-ribose and 17β-Estradiol as alternatives to exogenous VEGF to promote angiogenesis in tissue-engineered constructs

Aim: In this study, we explored the angiogenic potential and proangiogenic concentration ranges of 2-deoxy-D-ribose (2dDR) and 17β-Estradiol (E2) in comparison with VEGF. The 2dDR and E2 were then loaded into tissue engineering (TE) scaffolds to investigate their proangiogenic potential when released from fibers. Materials & methods: Ex ovo chick chorioallantoic membrane (CAM) assay was used to evaluate angiogenic activity of 2dDR and E2. Both factors were then introduced into scaffolds via electrospinning to assess their angiogenic potential when released from fibers. Results: Both factors were approximately 80% as potent as VEGF and showed a dose-dependent angiogenic response. The sustained release of both agents from the scaffolds stimulated neovascularization over 7 days in the chorioallantoic membrane assay. Conclusion: We conclude that both 2dDR and E2 provide attractive alternatives to VEGF for the functionalization of tissue engineering scaffolds to promote angiogenesis in vivo.

Unlockable Nanocomplexes with Self-Accelerating Nucleic Acid Release for Effective Staged Gene Therapy of Cardiovascular Diseases

Nucleic acid (NA)-based therapy is proposed to address serious diseases such as cardiovascular diseases (CVDs). Powerful NA delivery vehicles are essential for effective gene therapy. Herein, a novel type of delivery vehicle, an unlockable core-shell nanocomplex (Hep@PGEA) with self-accelerating NA release, is structurally designed. Hep@PGEA is composed of disulfide-bridged heparin nanoparticle (HepNP) core and low-toxicity PGEA cationic shell. In comparison with NA, heparin, a negatively charged polysaccharide macromolecule, exhibits stronger interactions with cationic species. Upon the breakdown of redox-responsive HepNP cores, unlocked heparin would interact with the outer cationic shells and replace the condensed NA to facilitate NA release. Such unique Hep@PGEA is successfully explored for effective miRNA-pDNA staged gene therapy of myocardial infarction (MI), one of the most serious CVDs. With the progression of MI, glutathione amounts in heart tissues increase. MiR-499 (for the inhibition of cardiomyocyte apoptosis) and plasmid encoding vascular endothelial growth factor (for the promotion of angiogenesis) are sequentially delivered for systemic treatment of MI. Such treatment produces impressive results in restoring heart function and suppressing cardiac hypertrophy. Due to the wide existence of redox agents in cells, the proposed unlockable delivery nanovehicle and staged therapy strategy can provide new methods to effectively treat different serious diseases.

Microwave-assisted synthesis and evaluation of type 1 collagen-apatite composites for dental tissue regeneration

The aim was to develop an economical and biocompatible collagen-based bioactive composite for tooth regeneration. Acid-soluble collagen was extracted and purified from fish scales. The design was innovated to molecularly tailor the surface charge sites of the nano-apatite providing chemical bonds with the collagen matrix via microwave irradiation technique. The obtained collagen was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. The composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry, and scanning electron microscopy. MC3T3-E1 cell lines were used to assess the biological effects of these materials by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetra zolium bromide (MTT) assay. Indirect contact test was performed by extracting representative elutes in cell culture media and sulforhodamine B analysis was performed. Chorioallantoic membrane assay was conducted to define the new vessels formation behavior. The purity of collagen extracts was determined and showed two α-chains, i.e. the characteristic of type I collagen. Fourier transform infrared spectroscopy showed the characteristic peaks for amide I, I, III, and phosphate for collagen and composites. Scanning electron microscopy images showed three-dimensional mesh of collagen/apatite nano-fibers. Nontoxic behavior of composites was observed and there were graded and dose-related effects on experimental compounds. The angiogenesis and vessels formation behavior were observed in bioactive collagen composite. The obtained composites have potential to be used for tooth structure regeneration.

Heparin binding chitosan derivatives for production of pro-angiogenic hydrogels for promoting tissue healing

Our aim was to develop a biocompatible hydrogel that could be soaked in heparin and placed on wound beds to improve the vasculature of poorly vascularized wound beds. In the current study, a methodology was developed for the synthesis of a new chitosan derivative (CSD-1). Hydrogels were synthesized by blending CSD-1 for either 4 or 24h with polyvinyl alcohol (PVA). The physical/chemical interactions and the presence of specific functional groups were confirmed by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (¹H NMR). The porous nature of the hydrogels was confirmed by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) showed that these hydrogels have good thermal stability which was slightly increased as the blending time was increased. Hydrogels produced with 24h of blending supported cell attachment more and could be loaded with heparin to induce new blood vessel formation in a chick chorionic allantoic membrane assay.