Electrospun PGA/gelatin nanofibrous scaffolds and their potential application in vascular tissue engineering

BACKGROUND AND METHODS

In this study, gelatin was blended with polyglycolic acid (PGA) at different ratios (0, 10, 30, and 50 wt%) and electrospun. The morphology and structure of the scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The mechanical properties were also measured by the tensile test. Furthermore, for biocompatibility assessment, human umbilical vein endothelial cells and human umbilical artery smooth muscle cells were cultured on these scaffolds, and cell attachment and viability were evaluated.

RESULTS

PGA with 10 wt% gelatin enhanced the endothelial cells whilst PGA with 30 wt% gelatin increased smooth muscle cell adhesion, penetration, and viability compared with the other scaffold blends. Additionally, with the increase in gelatin content, the mechanical properties of the scaffolds were improved due to interaction between PGA and gelatin, as revealed by Fourier transform infrared spectroscopy and differential scanning calorimetry.

CONCLUSION

Incorporation of gelatin improves the biological and mechanical properties of PGA, making promising scaffolds for vascular tissue engineering.

Delivery vehicle of muscle-derived irisin based on silk/calcium silicate/sodium alginate composite scaffold for bone regeneration

Background

Irisin is a cytokine produced by skeletal muscle and usually plays a pivotal role in inducing fat browning and regulating energy expenditure. In recent years, it was found that irisin might be the molecular entity responsible for muscle–bone connectivity and is useful in osteogenesis induction.

Materials and methods

To study its effect on bone regeneration, we developed silk/calcium silicate/sodium alginate (SCS) composite scaffold based on an interpenetrating network hydrogel containing silk fibroin, calcium silicate, sodium alginate. Then we loaded irisin on the SCS before coating it with polyvinyl alcohol (PVA). The SCS/P scaffold was physically characterized and some in vitro and in vivo experiments were carried out to evaluate the scaffold effect on bone regeneration.

Results

The SCS/P scaffold was showed a porous sponge structure pursuant to scanning electron microscopy analysis. The release kinetics assay demonstrated that irisin was stably released from the irisin-loaded hybrid system (i/SCS/P system) to 50% within 7 days. Moreover, osteoinductive studies using bone marrow stem cells (BMSCs) in vitro exhibited the i/SCS/P system improved the activity of alkaline phosphatase (ALP) and enhanced the expression levels of a series of osteogenic markers containing Runx-2, ALP, BMP2, Osterix, OCN, and OPN. Alizarin red staining also demonstrated the promotion of osteogenesis induced by i/SCS/P scaffolds. In addition, in vivo studies showed that increased bone regeneration with better mineralization and higher quality was found during the repair of rat calvarial defects through utilizing the i/SCS/P system.

Conclusion

These data provided strong evidence that the composite i/SCS/P would be a promising substitute for bone tissue engineering.

Human neural stem cell-derived cultures in three-dimensional substrates form spontaneously functional neuronal networks

Differentiated human neural stem cells were cultured in an inert three-dimensional (3D) scaffold and, unlike two-dimensional (2D) but otherwise comparable monolayer cultures, formed spontaneously active, functional neuronal networks that responded reproducibly and predictably to conventional pharmacological treatments to reveal functional, glutamatergic synapses. Immunocytochemical and electron microscopy analysis revealed a neuronal and glial population, where markers of neuronal maturity were observed in the former. Oligonucleotide microarray analysis revealed substantial differences in gene expression conferred by culturing in a 3D vs a 2D environment. Notable and numerous differences were seen in genes coding for neuronal function, the extracellular matrix and cytoskeleton. In addition to producing functional networks, differentiated human neural stem cells grown in inert scaffolds offer several significant advantages over conventional 2D monolayers. These advantages include cost savings and improved physiological relevance, which make them better suited for use in the pharmacological and toxicological assays required for development of stem cell-based treatments and the reduction of animal use in medical research. Copyright © 2015 John Wiley & Sons, Ltd.

Advances in Cell Transplantation Therapy for Limbal Stem Cell Deficiency

BACKGROUND

Limbal stem cells (LSCs) are essential for maintaining corneal transparency and ocular surface integrity. Many external factors or genetic diseases can lead to corneal limbal stem cell deficiency (LSCD), resulting in the loss of barrier and corneal epithelial cell renewal functions. Stem cell transplantation is one of the primary treatments for LSCD, including limbal transplantation and cultivated limbal epithelial transplantation. In addition, a variety of non-limbal stem cell lines have been experimented with for LSCD treatment. Biological scaffolds are also used to support in vitro stem cell culture and transplantation. Here, we review the mechanisms of corneal maintenance by LSCs, the clinical stage and surgical treatment of LSCD, the source of stem cells, and the biological scaffolds required for in vitro culture.

METHODS

This study is a narrative retrospective study aimed at collecting available information on various aspects of surgical treatments for LSCD. Relevant literature was searched in a range of online databases, including Web of Science, Scopus, and PubMed from 2005 to March, 2023.

RESULTS

A total of 397 relevant articles were found, and 49 articles with strong relevance to the studies in this paper were obtained and analyzed. Moreover, 11 of these articles were on the concept of LSCD and the mechanism of LESCs maintaining the corneal epithelium, 3 articles on the staging and grading of LSCD, 17 articles on cell transplantation methods and donor cell sources, and 18 articles on scaffolds for delivering stem cells. We also summarized the advantages and disadvantages of different cell transplantation methods and the benefits and limitations of scaffolds based on the above literature.

CONCLUSION

The treatment of LSCD is determined by the clinical stage and whether it involves monocular or binocular eyes. Appropriate surgical techniques should be taken for LSCD patients in order to reconstruct the ocular surface, relieve symptoms, and restore visual function. Meanwhile, biological scaffolds assist in the ex vivo culture and implantation of stem cells.

Electric field bridging-effect in electrified microfibrils' scaffolds

Introduction: The use of biocompatible scaffolds combined with the implantation of neural stem cells, is increasingly being investigated to promote the regeneration of damaged neural tissue, for instance, after a Spinal Cord Injury (SCI). In particular, aligned Polylactic Acid (PLA) microfibrils' scaffolds are capable of supporting cells, promoting their survival and guiding their differentiation in neural lineage to repair the lesion. Despite its biocompatible nature, PLA is an electrically insulating material and thus it could be detrimental for increasingly common scaffolds' electric functionalization, aimed at accelerating the cellular processes. In this context, the European RISEUP project aims to combine high intense microseconds pulses and DC stimulation with neurogenesis, supported by a PLA microfibrils' scaffold. Methods: In this paper a numerical study on the effect of microfibrils' scaffolds on the E-field distribution, in planar interdigitated electrodes, is presented. Realistic microfibrils' 3D CAD models have been built to carry out a numerical dosimetry study, through Comsol Multiphysics software. Results: Under a voltage of 10 V, microfibrils redistribute the E-field values focalizing the field streamlines in the spaces between the fibers, allowing the field to pass and reach maximum values up to 100 kV/m and values comparable with the bare electrodes' device (without fibers). Discussion: Globally the median E-field inside the scaffolded electrodes is the 90% of the nominal field, allowing an adequate cells' exposure.

Allografts for partial meniscus repair: an in vitro and ex vivo meniscus culture study

The purpose of this study was to evaluate the treatment potential of a human-derived demineralized scaffold, Spongioflex® (SPX), in partial meniscal lesions by employing in vitro models. In the first step, the differentiation potential of human meniscal cells (MCs) was investigated. In the next step, the ability of SPX to accommodate and support the adherence and/or growth of MCs while maintaining their fibroblastic/chondrocytic properties was studied. Control scaffolds, including bovine collagen meniscus implant (CMI) and human meniscus allograft (M-Allo), were used for comparison purposes. In addition, the migration tendency of MCs from fresh donor meniscal tissue into SPX was investigated in an ex vivo model. The results showed that MCs cultured in osteogenic medium did not differentiate into osteogenic cells or form significant calcium phosphate deposits, although AP activity was relatively increased in these cells. Culturing cells on the scaffolds revealed increased viability on SPX compared to the other scaffold materials. Collagen I synthesis, assessed by ELISA, was similar in cells cultured in 2D and on SPX. MCs on micro-porous SPX (weight >0.5 g/cm3) exhibited increased osteogenic differentiation indicated by upregulated expression of ALP and RUNX2, while also showing upregulated expression of the chondrogen-specific SOX9 and ACAN genes. Ingrowth of cells on SPX was observed after 28 days of cultivation. Overall, the results suggest that SPX could be a promising biocompatible scaffold for meniscal regeneration.

Bio-Based Polyurethane Networks Containing Sunflower Oil Based Polyols

This work focused on the preparation and investigation of polyurethane (SO-PU)-containing sunflower oil glycerides. By transesterification of sunflower oil with glycerol, we synthesized a glyceride mixture with an equilibrium composition, which was used as a new diol component in polyurethanes in addition to poly(ε-caprolactone)diol (PCLD2000). The structure of the glyceride mixture was characterized by physicochemical methods, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), nuclear magnetic resonance spectroscopy (NMR), and size exclusion chromatography (SEC) measurements. The synthesis of polyurethanes was performed in two steps: first the prepolymer with the isocyanate end was synthesized, followed by crosslinking with an additional amount of diisocyanate. For the synthesis of the prepolymer, 4,4'-methylene diphenyl diisocyanate (MDI) or 1,6-hexamethylene diisocyanate (HDI) were used as isocyanate components, while the crosslinking was carried out using an additional amount of MDI or HDI. The obtained SO-PU flexible polymer films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The so-obtained flexible SO-PU films were proved to be suitable for the preparation of potentially biocompatible and/or biodegradable scaffolds. In addition, the stress versus strain curves for the SO-PU polymers were interpreted in terms of a mechanical model, taking into account the yield and the strain hardening.