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

Electrospun bioresorbable polymer membranes for coronary artery stents

Percutaneous coronary intervention, a common treatment for atherosclerotic coronary artery lesions, occasionally results in perforations associated with increased mortality rates. Stents coated with a bioresorbable polymer membrane may offer an effective solution for sealing coronary artery perforations. Additionally, such coatings could be effective in mitigating neointimal hyperplasia within the vascular lumen and correcting symptomatic aneurysms. This study examines polymer membranes fabricated by electrospinning of polycaprolactone, polydioxanone, polylactide-co-caprolactone, and polylactide-co-glycolide. In uniaxial tensile tests, all the materials appear to surpass theoretically derived elongation thresholds necessary for stent deployment, albeit polydioxanone membranes are found to disintegrate during the experimental balloon expansion. As revealed by in vitro hemocompatibility testing, polylactide-co-caprolactone membranes exhibit higher thrombogenicity compared to other evaluated polymers, while polylactide-co-glycolide samples fail within the first day post-implantation into the abdominal aorta in rats. The PCL membrane exhibited significant water leakage in the permeability test. Comprehensive evaluation of mechanical testing, bio- and hemocompatibility, as well as biodegradation dynamics shows the advantage of membranes based on and the mixture of polylactide-co-caprolactone and polydioxanone over other polymer groups. These findings lay a foundational framework for conducting preclinical studies on stent configurations in large laboratory animals, emphasizing that further investigations under conditions closely mimicking clinical use are imperative for making definitive conclusions.

Human Keratinocytes and Fibroblasts Co-Cultured on Silk Fibroin Scaffolds Exosomally Overrelease Angiogenic and Growth Factors

Objectives: The optimal healing of skin wounds, deep burns, and chronic ulcers is an important clinical problem. Attempts to solve it have been driving the search for skin equivalents based on synthetic or natural polymers. Methods: Consistent with this endeavor, we used regenerated silk fibroin (SF) from Bombyx mori to produce a novel compound scaffold by welding a 3D carded/hydroentangled SF-microfiber-based nonwoven layer (C/H-3D-SFnw; to support dermis engineering) to an electrospun 2D SF nanofiber layer (ESFN; a basal lamina surrogate). Next, we assessed-via scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, mono- and co-cultures of HaCaT keratinocytes and adult human dermal fibroblasts (HDFs), dsDNA assays, exosome isolation, double-antibody arrays, and angiogenesis assays-whether the C/H-3D-SFnws/ESFNs would allow the reconstitution of a functional human skin analog in vitro. Results: Physical analyses proved that the C/H-3D-SFnws/ESFNs met the requirements for human soft-tissue-like implants. dsDNA assays revealed that co-cultures of HaCaTs (on the 2D ESFN surface) and HDFs (inside the 3D C/H-3D-SFnws) grew more intensely than did the respective monocultures. Double-antibody arrays showed that the CD9⁺/CD81⁺ exosomes isolated from the 14-day pooled growth media of HDF and/or HaCaT mono- or co-cultures conveyed 35 distinct angiogenic/growth factors (AGFs). However, versus monocultures' exosomes, HaCaT/HDF co-cultures' exosomes (i) transported larger amounts of 15 AGFs, i.e., PIGF, ANGPT-1, bFGF, Tie-2, Angiogenin, VEGF-A, VEGF-D, TIMP-1/-2, GRO-α/-β/-γ, IL-1β, IL-6, IL-8, MMP-9, and MCP-1, and (ii) significantly more strongly stimulated human dermal microvascular endothelial cells to migrate and assemble tubes/nodes in vitro. Conclusions: Our results showed that both cell-cell and cell-SF interactions boosted the exosomal release of AGFs from HaCaTs/HDFs co-cultured on C/H-3D-SFnws/ESFNs. Hence, such exosomes are an asset for prospective clinical applications as they advance cell growth and neoangiogenesis and consequently graft take and skin healing. Moreover, this new integument analog could be instrumental in preclinical and translational studies on human skin pathophysiology and regeneration.

Design and development of polydioxanone scaffolds for skin tissue engineering manufactured via green process

Fiber spinning technologies attracted a great interest since the beginning of the last century. Among these, electrospinning is a widely diffuse technique; however, it presents some drawbacks such as low fiber yield, high energy demand and the use of organic solvents. On the contrary, centrifugal spinning is a more sustainable method and allows to obtain fiber using centrifugal force and melted materials. The aim of the present work was the design and the development of polydioxanone (PDO) microfibers intended for tissue engineering, using centrifugal spinning. PDO, a bioresorbable polymer currently used for sutures, was selected as low melting polyester and DES (deep eutectic solvents), either choline chloride/citric acid (ChCl/CA) or betaine/citric acid (Bet/CA) 1:1 M ratio, were used to improve PDO spinnability. Physical mixtures of DES and PDO were prepared using different weight ratios. These were then poured into the spinneret and melted at 140 °C for 5 min. After the complete melting, the blends were spun for 1 min at 700 rpm. The fibers were characterized for physico chemical properties (morphology; dimensions; chemical structure; thermal behavior; mechanical properties). Moreover, the preclinical investigation was performed in vitro (biocompatibility, adhesion and proliferation of fibroblasts) and in vivo (murine burn/excisional model to assess safety and efficacy). The multidisciplinary approach allowed to obtain an extensive characterization to develop PDO based microfibers as medical device for implant to treat full thickness skin wounds.

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.