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.

Electrospun polydioxanone/fucoidan blend nanofibers loaded with anti-cancer precipitate from Jaspis diastra and paclitaxel: Physico-chemical characterization and in-vitro screening.

Nanofibers for drug delivery systems have gained much attention during the past years. This paper describes for the first time the loading of a bioactive precipitate (JAD) from the marine sponge Jaspis diastra in PDX and fucoidan-PDX. JAD was characterized by LC-MS/MS and the major component was jaspamide (1) with a purity of 62.66 %. The cytotoxicity of JAD was compared with paclitaxel (PTX). JAD and PTX displayed IC50 values of 1.10 ± 0.7 µg/mL and 0.21 ± 0.12 µg/mL on skin fibroblasts L929 cells whilst their IC50 values on uveal MP41 cancer cells, were 2.10 ± 0.55 µg/mL and 1.38 ± 0.68 µg/mL, respectively. JAD was found to be less cytotoxic to healthy fibroblasts compared to PTX. JAD and PTX loaded scaffolds showed sustained release over 96 h in physiological medium which is likely to reduce the secondary cytotoxic effect induced by JAD and PTX alone. The physico-chemical properties of the loaded and unloaded scaffolds together with their degradation and action on tumor microenvironment by using L929 and MP41 cells were investigated. JAD and PTX at a concentration of 0.5 % (drug/polymer, w/w) in the electrospun mats prevented growth and proliferation of L929 and MP41 cells. Co-culture of L929 and MP41 showed that the JAD and PTX loaded mats inhibited the growth of both cells and caused cell death.

Lignin-cellulose complexes derived from agricultural wastes for combined antibacterial and tissue engineering scaffolds for cutaneous leishmaniasis wounds.

Bacterial infections in wounds significantly impair the healing process. The use of natural antibacterial products over synthetic antibiotics has emerged as a new trend to address antimicrobial resistance. An ideal tissue engineering scaffold to treat infected wounds should possess antibacterial properties, while simultaneously promoting tissue regrowth. Synthesis of hydrogel scaffolds with antibacterial properties using hemp shive (HT1/HT2) lignin, sugarcane bagasse (SCB) lignin and cellulose was carried out. All lignin samples had low molecular weights and were constituted of G-type ß-5 dimers, linked by ß-O-4 bonds, as determined by MALDI-TOF-MS. Hemp lignin was more cytotoxic to mouse fibroblasts (L929) compared to SCB lignin. All lignin samples demonstrated antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis, with greater efficiency against Gram-negative strains. 3D hydrogels were engineered by crosslinking SCB lignin with SCB cellulose in varying weight ratios in the presence of epichlorohydrin. The stiffness of the hydrogels could be tailored by varying the lignin concentration. All hydrogels were biocompatible; however, better fibroblast adhesion was observed on the blended hydrogels compared to the 100% cellulose hydrogel, with the cellulose : lignin 70 : 30 hydrogel showing the highest L929 proliferation and best antibacterial properties with a 24-hour bacterial growth reduction ranging from 30.8 to 57.3%.

Electrospun nanofibrous scaffolds as a platform to reduce melanoma tumour growth, recurrence, and promote post-resection wound repair.

Wound healing following skin tumour surgery still remains a major challenge. To address this issue, polysaccharide-loaded nanofibrous mats have been engineered as skin patches on the wound site to improve wound healing while simultaneously eliminating residual cancer cells which may cause cancer relapse. The marine derived polysaccharides kappa-carrageenan (KCG) and fucoidan (FUC) were blended with polydioxanone (PDX) nanofibers due to their inherent anti-cancer activity conferred by the sulphate groups as well as their immunomodulatory properties which can reduce inflammation resulting in accelerated wound healing. KCG and FUC were released sustainably from the blend nanofibers via the Korsmeyer-Peppas kinetics. MTT assays, live/dead staining and SEM images demonstrated the toxicity of KCG and FUC towards skin cancer MP 41 cells. In addition, MP 41 cells showed reduced metastatic potential when grown on KCG or FUC containing mats. Both KCG and FUC were non- cytotoxic to healthy L 929 fibroblast cells. In vivo studies on healthy Wistar rats confirmed the non-toxicity of the nanofibrous patches as well as their improved and scarless wound healing potential. In vivo studies on tumour xenograft model further showed a reduction of 7.15 % in tumour volume in only 4 days following application of the transdermal patch.

Polysucrose hydrogel loaded with natural molecules/extracts for multiphase-directed sustainable wound healing.

Natural molecules/extracts have numerous beneficial effects on wound healing processes which are challenged by appropriate use and non-toxic dosage. Polysucrose-based (PSucMA) hydrogels have been synthesized with in situ loading of one or more natural molecules/extracts namely Manuka honey (MH), Eucalyptus honey (EH1, EH2), Ginkgo biloba (GK), thymol (THY) and metformin (MET). EH1 presented low amounts of hydroxymethylfurfural and methylglyoxal compared to MH indicating that EH1 was not temperature-abused. It also showed high diastase activity and conductivity. GK was added to PSucMA solution along with other additives including MH, EH1 and MET and crosslinked to form dual loaded hydrogels. The in vitro release profiles of EH1, MH, GK and THY from the hydrogels followed the exponential Korsmeyer-Peppas equation, with a release exponent value of less than 0.5 indicating a quasi-Fickian diffusion mechanism. The IC50 values of these natural products using L929 fibroblasts and RAW 264.7 macrophages indicated that EH1, MH and GK were cytocompatible at relatively high concentrations compared to MET, THY and curcumin used as a control. MH and EH1 induced high IL6 concentration compared to GK. In vitro studies were modelled to mimic the overlapping wound healing phases using human dermal fibroblasts (HDFs), macrophages and human umbilical endothelial cells (HUVECs) in dual culture. HDFs showed a highly interconnected cellular network on GK loaded scaffolds. EH1 loaded scaffolds were seen to induce formation of spheroids which increased in number and size in co-culture studies. The SEM images of HDF/HUVEC seeded GK, GKMH and GKEH1 loaded hydrogels indicated formation of vacuoles and lumen structures. These results indicated that a combination of GK and EH1 in the hydrogel scaffold would accelerate tissue regeneration by acting on the four overlapping phases of wound healing.

Health economics of diabetic foot ulcer and recent trends to accelerate treatment.

Diabetic foot ulcer is a preventable complication of diabetes that imposes a significant burden on the community. It leads to amputation and increased disability if left untreated and thus bears profound implications on the individual, the community and the health system at large. Diabetic foot (DF) is an area of research interest where interdisciplinary researchers are trying to elucidate the best strategy to halt the progression of chronic diabetic wounds. It is an area where tissue engineering research is making a strong impact through the use of scaffolds and skin substitutes for diabetic wound healing. This review aims at discussing the geographical health economics, its impact on healing and factors influencing financial costs of DFU. The upcoming economic and clinical impacts due to disease outbreak such as the 2020 COVID-19 has also been discussed. Finally, it will discuss novel therapy available with emphasis on skin tissue engineering scaffolds with a cost-benefit analysis. The review aims at promoting better management of people with diabetes with emphasis on emerging treatments and technologies.

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.

Nanomedicine-based strategies to improve treatment of cutaneous leishmaniasis.

Nanomedicine strategies were first adapted and successfully translated to clinical application for diseases, such as cancer and diabetes. These strategies would no doubt benefit unmet diseases needs as in the case of leishmaniasis. The latter causes skin sores in the cutaneous form and affects internal organs in the visceral form. Treatment of cutaneous leishmaniasis (CL) aims at accelerating wound healing, reducing scarring and cosmetic morbidity, preventing parasite transmission and relapse. Unfortunately, available treatments show only suboptimal effectiveness and none of them were designed specifically for this disease condition. Tissue regeneration using nano-based devices coupled with drug delivery are currently being used in clinic to address diabetic wounds. Thus, in this review, we analyse the current treatment options and attempt to critically analyse the use of nanomedicine-based strategies to address CL wounds in view of achieving scarless wound healing, targeting secondary bacterial infection and lowering drug toxicity.

A View on Genomic Medicine Activities in Africa: Implications for Policy.

Genomics policy development involves assessing a wide range of issues extending from specimen collection and data sharing to whether and how to utilize advanced technologies in clinical practice and public health initiatives. A survey was conducted among African scientists and stakeholders with an interest in genomic medicine, seeking to evaluate: 1) Their knowledge and understanding of the field. 2) The institutional environment and infrastructure available to them. 3) The state and awareness of the field in their country. 4) Their perception of potential barriers to implementation of precision medicine. We discuss how the information gathered in the survey could instruct the policies of African institutions seeking to implement precision, and more specifically, genomic medicine approaches in their health care systems in the following areas: 1) Prioritization of infrastructures. 2) Need for translational research. 3) Information dissemination to potential users. 4) Training programs for specialized personnel. 5) Engaging political stakeholders and the public. A checklist with key requirements to assess readiness for implementation of genomic medicine programs is provided to guide the process from scientific discovery to clinical application.

Marine sponge-derived/inspired drugs and their applications in drug delivery systems.

Oceans harbor a vast biodiversity that is not represented in terrestrial habitats. Marine sponges have been the richest source of marine natural products reported to date, and sponge-derived natural products have served as inspiration for the development of several drugs in clinical use. However, many promising sponge-derived drug candidates have been stalled in clinical trials due to lack of efficacy, off-target toxicity, metabolic instability or poor pharmacokinetics. One possible solution to this high clinical failure rate is to design drug delivery systems that deliver drugs in a controlled and specific manner. This review critically analyzes drugs/drug candidates inspired by sponge natural products and the potential use of drug delivery systems as a new strategy to enhance the success rate for translation into clinical use.

Assessing the mechanisms of action of natural molecules/extracts for phase-directed wound healing in hydrogel scaffolds.

Hydrogels are proving to be very versatile as wound healing devices. In addition to their capabilities of providing a moist cellular environment and adaptive mechanical properties mimicking the extracellular matrix, they allow the incorporation of small molecules, which have potential impacts on cellular behaviour, in their nanostructures. This strategy can allow for specific targeting of the different stages of wound healing namely hemostasis, inflammation, and proliferative and remodelling phases. The latter include interlinked processes such as angiogenesis, collagen synthesis, growth factor release, collagen maturation and re-epithelialization. In this review, we attempt to match the mechanisms of action of natural molecules/extracts to the different stages of wound healing so that they can be used in a novel approach of multiphase-directed tissue regeneration using loaded hydrogel scaffolds.

Green seaweeds ulvan-cellulose scaffolds enhance in vitro cell growth and in vivo angiogenesis for skin tissue engineering.

Cellulose has been extracted from a wide range of land resources, whereas it has been scarcely exploited from marine resources. Cellulose from green seaweeds can be extracted together with smaller molecules called ulvans. We have successfully extracted and characterized cellulose from Ulva sp. Solid state 13C NMR indicated the presence of ulvans in the cellulose extracts. The extracted cellulose was blended with polylactide and polydioxanone and electrospun into nanofibrous mats with a range of physico-chemical properties. These cellulose-based scaffolds were assessed in vitro using fibroblast cells and showed accelerated cell growth. In vivo biocompatibility studies using a Wistar rat model indicated the absence of foreign body response and enhanced angiogenesis.

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.

Repurposing nano-enabled polymeric scaffolds for tumor-wound management and 3D tumor engineering.

The main challenges of cancer drugs are toxicity, effect on wound healing/patient outcome and in vivo instability. Polymeric scaffolds have been used separately for tissue regeneration in wound healing and as anticancer drug releasing devices. Bringing these two together in bifunctional scaffolds can provide a tool for postoperative local tumor management by promoting healthy tissue regrowth and to deliver anticancer drugs. Another addition to the versatility of polymeric scaffold is its recently discovered ability to act as 3D cell culture models for in vitro isolation and amplification of cancer cells for personalized drug screening and to recapitulate the tumor microenvironment. This review focuses on the repurposing of 3D polymeric scaffolds for local tumor-wound management and development of in vitro cell culture models.

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.

Correlating in vitro performance with physico-chemical characteristics of nanofibrous scaffolds for skin tissue engineering using supervised machine learning algorithms.

The engineering of polymeric scaffolds for tissue regeneration has known a phenomenal growth during the past decades as materials scientists seek to understand cell biology and cell-material behaviour. Statistical methods are being applied to physico-chemical properties of polymeric scaffolds for tissue engineering (TE) to guide through the complexity of experimental conditions. We have attempted using experimental in vitro data and physico-chemical data of electrospun polymeric scaffolds, tested for skin TE, to model scaffold performance using machine learning (ML) approach. Fibre diameter, pore diameter, water contact angle and Young's modulus were used to find a correlation with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of L929 fibroblasts cells on the scaffolds after 7 days. Six supervised learning algorithms were trained on the data using Seaborn/Scikit-learn Python libraries. After hyperparameter tuning, random forest regression yielded the highest accuracy of 62.74%. The predictive model was also correlated with in vivo data. This is a first preliminary study on ML methods for the prediction of cell-material interactions on nanofibrous scaffolds.

Mimicking growth factors: role of small molecule scaffold additives in promoting tissue regeneration and repair.

The primary aim of tissue engineering scaffolds is to mimic the in vivo environment and promote tissue growth. In this quest, a number of strategies have been developed such as enhancing cell-material interactions through modulation of scaffold physico-chemical parameters. However, more is required for scaffolds to relate to the cell natural environment. Growth factors (GFs) secreted by cells and extracellular matrix (ECM) are involved in both normal repair and abnormal remodeling. The direct use of GFs on their own or when incorporated within scaffolds represent a number of challenges such as release rate, stability and shelf-life. Small molecules have been proposed as promising alternatives to GFs as they are able to minimize or overcome many shortcomings of GFs, in particular immune response and instability. Despite the promise of small molecules in various TE applications, their direct use is limited by nonspecific adverse effects on non-target tissues and organs. Hence, they have been incorporated within scaffolds to localize their actions and control their release to target sites. However, scanty rationale is available which links the chemical structure of these molecules with their mode of action. We herewith review various small molecules either when used on their own or when incorporated within polymeric carriers/scaffolds for bone, cartilage, neural, adipose and skin tissue regeneration.

Improved Multicellular Response, Biomimetic Mineralization, Angiogenesis, and Reduced Foreign Body Response of Modified Polydioxanone Scaffolds for Skeletal Tissue Regeneration.

The potential of electrospun polydioxanone (PDX) mats as scaffolds for skeletal tissue regeneration was significantly enhanced through improvement of the cell-mediated biomimetic mineralization and multicellular response. This was achieved by blending PDX ( i) with poly(hydroxybutyrate- co-valerate) (PHBV) in the presence of hydroxyapatite (HA) and ( ii) with aloe vera (AV) extract containing a mixture of acemannan/glucomannan. In an exhaustive study, the behavior of the most relevant cell lines involved in the skeletal tissue healing cascade, i.e. fibroblasts, macrophages, endothelial cells and preosteoblasts, on the scaffolds was investigated. The scaffolds were shown to be nontoxic, to exhibit insignificant inflammatory responses in macrophages, and to be degradable by macrophage-secreted enzymes. As a result of different phase separation in PDX/PHBV/HA and PDX/AV blend mats, cells interacted differentially. Presumably due to varying tension states of cell-matrix interactions, thinner microtubules and significantly more cell adhesion sites and filopodia were formed on PDX/AV compared to PDX/PHBV/HA. While PDX/PHBV/HA supported micrometer-sized spherical particles, nanosized rod-like HA was observed to nucleate and grow on PDX/AV fibers, allowing the mineralized PDX/AV scaffold to retain its porosity over a longer time for cellular infiltration. Finally, PDX/AV exhibited better in vivo biocompatibility compared to PDX/PHBV/HA, as indicated by the reduced fibrous capsule thickness and enhanced blood vessel formation. Overall, PDX/AV blend mats showed a significantly enhanced potential for skeletal tissue regeneration compared to the already promising PDX/PHBV/HA blends.

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.