Polysucrose hydrogel and nanofiber scaffolds for skin tissue regeneration: Architecture and cell response.

Scaffolds capable of mediating overlapping multi-cellular activities to support the different phases of wound healing while preventing scarring are essential for tissue regeneration. The potential of polysucrose as hydrogels and electrospun mats for wound healing was evaluated in vitro by seeding fibroblasts, endothelial cells and macrophages either singly or in combination. It was found that the scaffold architecture impacted cell behaviour. Electrospun mats promoted fibroblasts flattened morphology while polysucrose methacrylate (PSucMA) hydrogels promoted fibroblast spheroids formation, accentuated in the presence of endothelial cells. Hydrogels exhibited lower inflammatory response than mats and curcumin loaded scaffolds reduced TNF-α production. In vivo biocompatibility of the hydrogels tested on Wistar rats was superior to electrospun mats. In vivo wound healing studies indicated that PSucMA hydrogels integrated the surrounding tissue with better cellular infiltration and proliferation throughout the entire wound region. PSucMA hydrogels led to scarless wound closure comparable with commercially available gels.

Piezoelectric core-shell PHBV/PDX blend scaffolds for reduced superficial wound contraction and scarless tissue regeneration.

The use of non-invasive scaffold materials which can mimic the innate piezoelectric properties of biological tissues is a promising strategy to promote native tissue regeneration. Piezoelectric and cell instructive electrospun core-shell PDX/PHBV mats have been engineered to promote native tissue and skin regeneration. In depth physicochemical characterisation, in vitro and in vivo studies of a rat model showed that the 20/80 PDX/PHBV composition possessed the right balance of physicochemical and piezoelectric properties leading to enhanced fibroblast stimulation, proliferation and migration, reduced fibroblast-mediated contraction and macrophage-induced inflammation, improved keratinocyte proliferation, proper balance between endothelial cell phenotypes, decreased in vivo fibrosis and accelerated in vivo scarless wound regeneration. Overall, this study highlights the importance of exploiting cell-material interactions to match tissue biological needs to sustain the wound healing cascade.

Sugar-cane bagasse cellulose-based scaffolds promote multi-cellular interactions, angiogenesis and reduce inflammation for skin tissue regeneration.

In a previous article, we reported on the physico-chemical properties of cellulose-based scaffolds derived from sugar-cane bagasse and their preliminary in vitro assessment. In view of skin tissue regeneration, we here present our findings of an extensive in vitro testing of these scaffolds using key cells involved in the wound healing cascade namely fibroblasts, keratinocytes, endothelial cells and macrophages either singly or in various combinations to mimic in vivo conditions. Inflammation was quantified using TNF-α. In vivo biocompatibility as well as wound healing potential of the scaffolds was demonstrated using Wistar rats. Finally, we discuss the effect of curcumin-loaded scaffolds on inflammation and angiogenesis in vitro and in vivo. Nanosilica extracted from sugar-cane bagasse ash was also loaded in the scaffolds and its effect on biological response was assessed.

Enhanced effects of curcumin encapsulated in polycaprolactone-grafted oligocarrageenan nanomicelles, a novel nanoparticle drug delivery system.

One of the most effective strategies to enhance the bioavailability and the therapeutic effect of hydrophobic drugs is the use of nanocarriers. We have used κ-carrageenan extracted from Kappaphycus alvarezii to produce oligocarrageenan via an enzymatic degradation process. Polycaprolactone (PCL) chains were grafted onto the oligocarrageenans using a protection/deprotection technique yielding polycaprolactone-grafted oligocarrageenan. The resulting amphiphilic copolymers formed spherical nanomicelles with a mean size of 187 ± 21 nm. Hydrophobic drugs such as curcumin were efficiently encapsulated in the micelles and released within 24-72 h in solution. The micelles were non-cytotoxic and facilitated the uptake of curcumin by endothelial EA-hy926 cells. They also increased the anti-inflammatory effect of curcumin in TNF-alpha-induced inflammation experiments. Finally, in vivo experiments supported a lack of toxicity in zebrafish and thus the potential use of polycaprolactone-grafted oligocarrageenan to improve the delivery of hydrophobic compounds to different organs, including liver, lung and brain as shown in mice.

Modulating matrix-multicellular response using polysucrose-blended with poly-L-lactide or polydioxanone in electrospun scaffolds for skin tissue regeneration.

Polysucrose (PSuc) is hydrophilic, has excellent biocompatibility with cells as a density gradient and is resistant to enzymes. Its use in electrospun mats for tissue engineering applications has not been investigated due to its amorphous nature. For spinnability and robustness, polysucrose was blended with poly-L-lactide (PLLA) and polydioxanone (PDX) respectively and electrospun into nanofibrous mats. Interaction with cells was assessed using L929 mouse fibroblasts and HaCaT keratinocytes separately and in co-culture. Effect of parameters such as porosity, fiber diameter, surface wettability and mechanical properties of mats on cell-scaffold interactions was studied. Depending on nature and composition of mats, fibroblasts showed dendritic, spindle or round cell morphologies along with the formation of lamellipodia, filopodia, fibrillar or fiber-like projections of 100 nm and 200-300 nm in diameter respectively from the periphery or center of cells. Granular extracellular matrix was formed on both PLLA-PSuc and PDX-PSuc 50-50 seeded with keratinocytes. Growth of keratinocytes was enhanced in co-culture with fibroblasts with the formation of a skin-like layer. Both cells showed the ability to form multilayer structures. The mats maintained their physical integrity during the period of study. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3275-3291, 2018.

Enhanced Differentiation of Human Preosteoblasts on Electrospun Blend Fiber Mats of Polydioxanone and Anionic Sulfated Polysaccharides.

The viability and differentiation of SaOS-2 preosteoblasts on fiber mats of blends comprising of the biodegradable poly(ester-ether) polydioxanone (PDX) and the sulfate-containing anionic polysaccharides kappa-carrageenan (KCG) and fucoidan (FUC) were investigated for a range of different blend compositions. The detailed analysis of the blend nanofiber properties revealed a different degree of miscibility of PDX and the polysaccharide leading to a different enrichment at the surface of the blend nanofibers, which were observed to be stable in phosphate buffer solution (PBS) for up to 5 weeks. The fibrous mats of PDX/FUC led to the highest osteogenic differentiation with very good cell viability. The electrospun blend fibers also supported human-induced pluripotent stem (iPS) cells and iPS cell-derived embryoid bodies with high cell viability, which underlines the potential of these novel blend fiber systems for optimized performance in bone tissue engineering applications.

Sugar-cane bagasse derived cellulose enhances performance of polylactide and polydioxanone electrospun scaffold for tissue engineering.

Bagasse is a waste product of sugar extraction from sugar-cane with approximately 30% cellulose content. Cellulose was successfully extracted from sugar-cane bagasse using a modified mercerization-bleaching approach with a 40% yield. Extracted cellulose was converted to cellulose acetate for enhanced electrospinnability and blended with poly-l-Lactide or polydioxanone before solution electrospinning. Physico-chemical evaluation of the electrospun mats showed variable miscibility of blends. In vitro cell studies with L929 mouse fibroblast cells was quite conclusive as regards the biocompatibility of the blended mats with proliferative behavior of cells, extracellular matrix deposition and characteristic features of healthy cellular response. MTT assay indicated that the cellulose blended mats induced higher cell densities than the controls. Cellulose content influenced parameters such as fiber diameter, porosity and cell-matrix interaction of mats impacting on cell growth and behavior. Preliminary assessment of biomineralization potential of the mats by SEM showed nano-hydroxyapatite deposits on the electrospun fibers.

Biomineralization potential and cellular response of PHB and PHBV blends with natural anionic polysaccharides.

In this paper, the biomineralization potential and cellular response of novel blend films of the anionic sulfated polysaccharides kappa-carrageenan (KCG) and fucoidan (FUC) derived from seaweeds with semi-crystalline polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV), respectively, were analyzed. The incorporation of KCG and FUC into PHB and PHBV, which has been studied here for the first time, led to an overall decrease in crystallinity, enhanced surface hydrophilicity, reduced brittleness and faster degradation of the polymer blend films. All PHB/KCG, PHBV/KCG and PHBV/FUC films exhibited a two-stage mass loss profiles with pH stabilization. PHBV/KCG film showed the highest biomineralization activity due the presence of sulfate groups on the surface of the films. NIH3T3 cells attached and proliferated well on all blend films on account of enhanced surface hydrophilicity and improved flexibility. PHBV/KCG led to a promoted cellular activity compared to PHBV/FUC, presumably due to phase separation and higher amount of biopolymer on the film surface that was a consequence of the immiscibility of the polymers in the blend films.

Ultrasound-assisted extraction and structural characterization by NMR of alginates and carrageenans from seaweeds.

Polysaccharides from seaweeds are interesting materials for food and pharmaceutical applications such as drug delivery due to their biocompatibility and biodegradability. Extraction of these biopolymers is usually performed during several hours to obtain a significant extraction yield. In this paper, we report on a new process to extract alginates from brown seaweeds (Sargassum binderi and Turbinaria ornata) and carrageenans from red seaweeds (Kappaphycus alvarezii and Euchema denticulatum) with the assistance of ultrasound. The effect of several parameters (pH, temperature, algae/water ratio, ultrasound power and duration) was investigated to determine optimal extraction conditions. The extracted polysaccharides represented up to 55% of the seaweeds dry weight and were obtained in a short time (15-30min) as compared to 27% in 2h for conventional extraction. NMR, FTIR and SEC analysis were used to characterise the extracted polymers. Ultrasound allowed the reduction of extraction time without affecting the chemical structure and molar mass distribution of alginates and carrageenans.

κ-Carrageenan Enhances the Biomineralization and Osteogenic Differentiation of Electrospun Polyhydroxybutyrate and Polyhydroxybutyrate Valerate Fibers.

Novel electrospun materials for bone tissue engineering were obtained by blending biodegradable polyhydroxybutyrate (PHB) or polyhydroxybutyrate valerate (PHBV) with the anionic sulfated polysaccharide κ-carrageenan (κ-CG) in varying ratios. In both systems, the two components phase separated as shown by FTIR, DSC and TGA. According to the contact angle data, κ-CG was localized preferentially at the fiber surface in PHBV/κ-CG blends in contrast to PHB/κ-CG, where the biopolymer was mostly found within the fiber. In contrast to the neat polyester fibers, the blends led to the formation of much smaller apatite crystals (800 nm vs 7 µm). According to the MTT assay, NIH3T3 cells grew in higher density on the blend mats in comparison to neat polyester mats. The osteogenic differentiation potential of the fibers was determined by SaOS-2 cell culture for 2 weeks. Alizarin red-S staining suggested an improved mineralization on the blend fibers. Thus, PHBV/κ-CG fibers resulted in more pronounced bioactive and osteogenic properties, including fast apatite-forming ability and deposition of nanosized apatite crystals.

Mixed poly(vinyl pyrrolidone)-based drug-loaded nanomicelles shows enhanced efficacy against pancreatic cancer cell lines.

We report in this paper on the enhanced efficacy of a physical mixture of two single anti-cancer loaded nanomicelles against PANC-1 and BxPC-3. Poly(vinyl pyrrolidone-b-polycaprolactone) (PVP-b-PCL) and poly(vinyl pyrrolidone-b-poly(dioxanone-co-methyl dioxanone)) (PVP-b-P(DX-co-MeDX)) were synthesized and successfully loaded with various anti-cancer drugs - gemcitabine (GEM), doxorubicin.HCl (DOX.HCl), doxorubicin.NH2 (DOX), 5-fluorouracil (5-FU) and paclitaxel (PTX). Spherical micelles of size 160-477 nm were obtained as characterized by DLS while sizes determined by TEM were in the range 140-250 nm. The hydrophobic drugs had a higher loading percentage efficiency compared to hydrophilic drugs in the trend PTX>DOX>5-FU>GEM>DOX.HCl whereas the drug release pattern followed the reverse trend in accordance with decreased polymer-drug interaction as quantified by the binding constant and micellar drug location. Cellular uptake studies showed that nanomicelles are taken up by pancreatic cancer cells into the cytoplasm and nucleus. The free nanomicelles were confirmed to be non-cytotoxic. A physical mixture of GEM loaded micelles and DOX.HCl loaded micelles of comparable size showed significantly higher cytotoxicity than either the free drug mixture or the individual single drug loaded micelles as confirmed by their IC50 values.

Artemisinin and its derivatives in cancer therapy: status of progress, mechanism of action, and future perspectives.

Since the late 1990s, there has been rapid multiplication of data on the anti-cancer properties of artemisinins. This article reviews the status of progress of artemisinin and its derivatives as anti-cancer agents in clinical trials, case reports, and in vitro/in vivo studies. Particular attention is laid on the combinations of artemisinins and synthetic chemodrugs to enhance the latter's efficacy. An attempt is here made to rationalize the synergistic effects of a few common anti-cancer drugs of the anthracycline, taxane, anti-metabolite, and platinum-based drug families. The various pathways that mediate the action of artemisinins as reported over the past decade are here summarized highlighting also the biomarkers that could be used to better predict the efficacy of the sesquiterpenoids. Their main action seems to be directed toward stalling tumor cell proliferation through cell cycle arrest mediated by reactive oxygen species (ROS). The emergence of artemisinins' nano-based formulations in combination with chemodrugs to enhance drug bioavailability and targeting as well as immunotherapy is also reviewed. The enhanced efficacy of artemisinin dimers compared to the parent molecules and standard chemotherapy is analyzed. While these therapies hold promises, it may be premature to conclude on their efficacy in the absence of clinical studies.

Cell-matrix mechanical interaction in electrospun polymeric scaffolds for tissue engineering: Implications for scaffold design and performance.

Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine. STATEMENT OF SIGNIFICANCE: Tissue engineering requires design of scaffolds that interact with cells to promote tissue development. Electrospinning is a promising technique for fabricating fibrous, biomimetic scaffolds. Effects of electrospun matrix microstructure and biochemical properties on cell behavior have been extensively reviewed previously; here, we consider cell-matrix interaction from a mechanical perspective. Micromechanical properties as a driver of cell behavior has been well established in planar substrates, but more recently, many studies have provided new insights into mechanical interaction in fibrillar, electrospun environments. This review provides readers with an overview of how electrospun scaffold mechanics and cell behavior work in a dynamic feedback loop to drive tissue development, and discusses opportunities for improved design of mechanical environments that are conducive to tissue development.

Third generation poly(hydroxyacid) composite scaffolds for tissue engineering.

Bone tissue engineering based on scaffolds is quite a complex process as a whole gamut of criteria needs to be satisfied to promote cellular attachment, proliferation and differentiation: biocompatibility, right surface properties, adequate mechanical performance, controlled bioresorbability, osteoconductivity, angiogenic cues, and vascularization. Third generation scaffolds are more of composite types to maximize biological-mechanical-chemical properties. In the present review, our focus is on the performance of micro-organism-derived polyhydroxyalkanoates (PHAs)-polyhydroxybutyrate (PHB) and polyhydroxybutyrate-co-valerate (PHBV)-composite scaffolds with ceramics and natural polymers for tissue engineering applications with emphasis on bone tissue. We particularly emphasize on how material properties of the composites affect scaffold performance. PHA-based composites have demonstrated their biocompatibility with a range of tissues and their capacity to induce osteogenesis due to their piezoelectric properties. Electrospun PHB/PHBV fiber mesh in combination with human adipose tissue-derived stem cells (hASCs) were shown to improve vascularization in engineered bone tissues. For nerve and skin tissue engineering applications, natural polymers such as collagen and chitosan remain the gold standard but there is scope for development of scaffolds combining PHAs with other natural polymers which can address some of the limitations such as brittleness, lack of bioactivity and slow degradation rate presented by the latter. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1667-1684, 2017.

Metformin in pancreatic cancer treatment: from clinical trials through basic research to biomarker quantification.

PURPOSE: Three major chemotherapy strategies have emerged in the treatment of PDAC in the recent past: multiple drug combination, stroma depletion, and use of nanodrug therapy. Anti-diabetic metformin was shown to improve the outcome of a number of cancer types the first seminal report on an observational study published in 2005 and the first hospital-based case-control study on pancreatic cancer in 2009. METHODS: In this review paper, we confront the findings of a selected number of epidemiological studies and clinical trials on the use of metformin in pancreatic cancer treatment with basic knowledge and research. We particularly emphasize on the point that contradictory clinical results likely originate from heterogeneous study design due to a trial and error approach rather than an evidence-based and scientific approach. A non-rigorous selection of patients suffering from PDAC and often a poor understanding of the biological mechanism of metformin coupled with lack of scientific data has led to general statements on metformin positive or negative action, another aspect which we highlight in the review. RESULTS: We here present a few pathways which in our opinion are predominant for pancreatic cancer specifically: mitochondrial activity, AMPK activation, mTOR inhibition, and decreased IGF-1R and HIF-1α expression. CONCLUSION: We stress on the need for a better stratification of patients and a more rigorous planning of clinical trials not only focusing on classical parameters but also on potential predictive biomarkers (AMPK, mTOR, HIF-1α, IGF-1R) and metformin dosage for positive outcome.

Polydioxanone-based bio-materials for tissue engineering and drug/gene delivery applications.

Since the commercialization of polydioxanone (PDX) as a biodegradable monofilament suture by Ethicon in 1981, the polymer has received only limited interest until recently. The limitations of polylactide-co-glycolide (PLGA) coupled with the growing need for materials with enhanced features and the advent of new fabrication techniques such as electrospinning have revived interest for PDX in medical devices, tissue engineering and drug delivery applications. Electrospun PDX mats show comparable mechanical properties as the major structural components of native vascular extracellular matrix (ECM) i.e. collagen and elastin. In addition, PDX's unique shape memory property provides rebound and kink resistance when fabricated into vascular conduits. The synthesis of methyl dioxanone (MeDX) monomer and copolymers of dioxanone (DX) and MeDX have opened up new perspectives for poly(ester-ether)s, enabling the design of the next generation of tissue engineering scaffolds for application in regenerating such tissues as arteries, peripheral nerve and bone. Tailoring of polymer properties and their formulation as nanoparticles, nanomicelles or nanofibers have brought along important developments in the area of controlled drug or gene delivery. This paper reviews the synthesis of PDX and its copolymers and provides for the first time an exhaustive account of its applications in the (bio)medical field with focus on tissue engineering and drug/gene delivery.

New avenues for improving pancreatic ductal adenocarcinoma (PDAC) treatment: Selective stroma depletion combined with nano drug delivery.

The effectiveness of chemotherapy in PDAC is hampered by the dynamic interaction between stroma and cancer cell. The two opposing schools of thought - non-depletion of the stroma vs its depletion - to better drug efficacy are here discussed. Disrupting stroma-cancer cell interaction to reduce tumor progression and promote apoptosis is identified as the new direction of treatment for PDAC. Clinical data have shown that elimination of fibrosis and blockade of the Hedgehog pathway in stroma effectively promote drug delivery to tumor site and apoptosis. Reduced stiffness of ECM, lower fibrosis, higher permeability and higher blood flow after stroma depletion increase drug delivery. Combination strategies involving selective stroma depletion coupled with chemotherapy is currently proving to be the most efficient at clinical level. Striking the right balance between fibrosis depletion and angiogenesis promotion resulting in enhanced drug delivery and apoptosis is a major challenge. The use of nano drug delivery devices coupled with stroma depletion is emerging as the next phase treatment for PDAC. The breakthrough to combat PDAC will likely be a combination of early diagnosis and the emerging chemotherapy strategies.

Naltrexone: a review of existing sustained drug delivery systems and emerging nano-based systems.

Narcotic antagonists such as naltrexone (NTX) have shown some efficiency in the treatment of both opiate addiction and alcohol dependence. A few review articles have focused on clinical findings and pharmacogenetics of NTX, advantages and limitations of sustained release systems as well as pharmacological studies of NTX depot formulations for the treatment of alcohol and opioid dependency. To date, three NTX implant systems have been developed and tested in humans. In this review, we summarize the latest clinical data on commercially available injectable and implantable NTX-sustained release systems and discuss their safety and tolerability aspects. Emphasis is also laid on recent developments in the area of nanodrug delivery such as NTX-loaded micelles and nanogels as well as related research avenues. Due to their ability to increase the therapeutic index and to improve the selectivity of drugs (targeted delivery), nanodrug delivery systems are considered as promising sustainable drug carriers for NTX in addressing opiate and alcohol dependence.

Polymeric nanomicelles for sustained delivery of anti-cancer drugs.

In the first section of this paper, the existing and emerging nanotechnology-based cancer therapies--nanoparticles, drug conjugates, nanomicelles--are reviewed. In a second part, we present our original and unpublished findings on the sustained release of anti-cancer drugs such as paclitaxel, doxorubicin and camptothecin using block copolymer micelles [PEG-b-poly(dioxanone-co-methyl dioxanone)]. Copolymers with variable lengths of hydrophobic and hydrophilic blocks have been synthesized and successfully loaded with paclitaxel, doxorubicin and camptothecin anti-cancer drugs, with micelles size in the range 130-300 nm. Drug encapsulation efficiencies varied between 15% and 70% depending on drug and copolymer composition. The drug binding constants, which give a good insight into drug encapsulation and release, were evaluated from UV spectroscopy as we reported previously for anti-TB drugs. Through variation of the methyl dioxanone content of the copolymer, our systems can be tailored for sustained release of the different drugs.

Poly(ester-ether)s: II. Properties of electrospun nanofibres from polydioxanone and poly(methyl dioxanone) blends and human fibroblast cellular proliferation.

This article deals with an in-depth study of the thermal, mechanical and degradation behaviours of nanofibres from polydioxanone (PDX) and polydl-3-methyl-1,4-dioxan-2-one (PMeDX) and a comparison with their blend films. Varying ratios of both polymers were blended and electrospun from solution. Electrospun fibres exhibited a melting transition at 109 °C independently of the PMeDX content, which corresponds to the melting of PDX nanofibres. As a result of the drawing process, PMeDX had a reduced plasticizing effect on PDX. In general, it was observed that overall crystallinity of the fibres decreased from 53% to 36% with increasing PMeDX content and this impacted on their mechanical properties. The Young's moduli decreased as the PMeDX content of the fibres increased. However, an increase in strain at break and peak stress was noted as a result of a decrease in the fibre diameter. AFM images of the electrospun fibres showed an increasing degree of morphological heterogeneity with increasing PMeDX content. Thermal degradation studies showed that electrospun mats were thermally more stable than blend films, as confirmed by a two-fold increase in activation energy. The hydrolytic degradation of the electrospun mats conducted in phosphate buffer solution at 37 °C showed that the degradation followed a surface erosion mechanism as opposed to bulk degradation observed for blend films. Degradation of fibres was found to be mainly dependent on their diameter. On the other hand, the degradation of blend films depended on the overall crystallinity of the blends. Electrospun PDX/PMeDX nanofibrous scaffolds were also subjected to cell viability studies with human dermal fibroblasts, in which they did not show illicit response and demonstrated excellent cell attachment and proliferation.