New dimensions of electrospun nanofiber material designs for biotechnological uses

Fabrication of polydopamine-altered PCL/PLGA nanofibrous scaffolds on cerium to enhance cytocompatibility, microbial inhibition, and improved osteogenic properties for tissue regeneration in orofacial treatment

Biodegradable scaffolds have significant potential for directed tissue regeneration in craniofacial and oral applications and bone regeneration. We designed an innovative cerium-altered/collagen-clacked polycaprolactone/poly-lactic-co-glycolic acid (PC/PL) electrospun scaffolds (PC/PL-PD-Ce-CL) to address the deficiencies of existing scaffold materials regarding osteogenic and antimicrobial characteristics. Novel scaffolds were developed by electrospinning a fundamental PCL/PLGA matrix, impregnating in situ reduction with cerium nanoparticles (CeNPs), applying a polydopamine coating, and clacking with collagen. The mechanical tests and scanning electron microscope demonstrated that the distinctive NSs preserved their tensile strength and elasticity modulus post-modification. The cell proliferation CCK-8 assay indicated that the PC/PL-PD-Ce-CL NSs exhibited a superior MG63 cell proliferation and cell adhesion ratio compared to the rest of the NSs. The alkaline phosphatase (ALP) activity and the expression levels of BMP2 and RUNX2 in MG63 cells cultivated on PC/PL-PD-Ce-CL NSs for 7 and 14 days were considerably elevated compared to the controls. The PC/PL-PD-Ce-CL and PC/PL-PD-Ce NSs exhibited a broader antibacterial zone compared to the control NSs, and bacterial fluorescence diminished on the Ce-altered NSs of incubation with S. mutans and S. aureus. Our innovative PC/PL-PD-Ce-CL NSs improved cytocompatibility, osteogenesis, and antibacterial capabilities, demonstrating their promising therapeutic applications for orofacial treatment.

Bi-phasic integrated silk fibroin/polycaprolactone scaffolds for osteochondral regeneration inspired by the native joint tissue and interface

Osteochondral scaffolds designed with bi-phasic and multi-phasic have typically struggled with post-implantation delamination. To address this issue, we developed a novel integrated scaffold with natural and continuous interface and heterogeneous bilayer structure. Through layer-by-layer wet electrospinning, two-dimensional (2D) bi-layer integrated membranes of silk fibroin (SF) and polycaprolactone (PCL) were fabricated. These membranes were then transformed into three-dimensional (3D) scaffolds using a CO2 gas foaming technique, followed by gelatin coating on the osteogenic layer to afford final bi-phasic porous scaffolds. In vitro studies indicated that the 3D scaffolds better-maintained cell phenotypes than conventional 2D electrospun films. Additionally, the 3D scaffolds showed superior cartilage repair and osteoinductivity potential, with increased subchondral bone volume and reduced defect area in rat osteochondral defects models at 12 weeks. Taken together, these gas-foamed scaffolds were a promising candidate for osteochondral regeneration.

NanoCRISPR-assisted biomimetic tissue-equivalent patch regenerates the intervertebral disc by inhibiting endothelial-to-mesenchymal transition

The integrity of the intervertebral disc (IVD), an immune-privileged organ protected by the blood-disc barrier, is compromised following annulus fibrosus (AF) injury. This breach facilitates angiogenesis, immune cell infiltration, and inflammation, accelerating intervertebral disc degeneration (IDD) and resulting in various clinical disorders. Current treatments fail to adequately address biological repair of AF defects and angiogenesis. Single-cell RNA sequencing analyses reveal that vascular endothelial growth factor (VEGF), secreted by IDD-associated fibrochondrocytes, is crucial in promoting angiogenesis by inducing endothelial-to-mesenchymal transition (EndoMT). This study proposes a nano-clustered regularly interspaced short palindromic repeats (CRISPR)-assisted AF patch with an aligned, polydopamine-modified nano-lamellae nanofibrous scaffold that replicates the hierarchical structure of natural AF, providing a conducive microenvironment for AF repair. A zeolitic imidazolate framework-8-based nanoCRISPR system encapsulates the CRISPR/CRISPR-associated protein 9 complex to target and eliminate VEGF-mediated angiogenic factors. In vitro studies demonstrate that the nanoCRISPR-assisted patch can enhance AF cell adhesion and migration, promote extracellular matrix deposition, knock out VEGF expression, and inhibit EndoMT. In vivo studies show its significant efficacy in promoting AF repair, inhibiting abnormal angiogenesis, and delaying IDD progression. This study presents a promising approach for structural and biological AF regeneration, addressing physical and angiogenic barriers in IVD regeneration.

Biological Coatings: Advanced Strategies Driving Multifunctionality and Clinical Potential in Dermal Substitutes

Skin tissue defects caused by various acute and chronic etiologies frequently occur in clinical medicine. Traditional surgical repair methods have certain limitations, while dermal substitutes combined with skin grafting have become an alternative to conventional surgery. Biological coatings, by loading bioactive substances such as polysaccharides and proteins, or by using bioactive substances as carriers, can promote cell adhesion, proliferation, and differentiation. This optimizes the mechanical properties and biocompatibility of the substitutes, enhances their antibacterial properties, and improves their feasibility for clinical application. This paper explores various common biological coating materials and the construction methods used in the field of dermal substitutes. It highlights the importance and necessity of biological coatings in the development of multifunctional designs for dermal substitutes. By summarizing the current research, this paper aims to offer new insights and references for the multifunctional design and clinical application of dermal substitutes.

Electrospun 11β-HSD1 Inhibitor-Loaded Scaffolds for Accelerating Diabetic Ulcer Healing

Diabetic ulcers (DUs) are a common and severe complication of diabetes, characterized by impaired wound healing due to a complex pathophysiological mechanism. Elevated levels of 11β-hydroxysteroid dehydrogenase type I (11β-HSD1) in wounds have been demonstrated to modulate glucocorticoid activity, leading to delayed skin cell proliferation and restricted angiogenesis, ultimately hindering wound healing. In this study, we propose an electrospun poly(ε-caprolactone) (PCL) nanofiber scaffold doped with the 11β-HSD1 inhibitor BVT2733 (BPs) to prevent 11β-HSD1 activity during the diabetic wound healing process. The electrospun scaffold loaded with BVT2733 is designed to achieve localized inhibition of 11β-HSD1 in DUs. This scaffold exhibited a porous morphology and desirable drug-loading capacity, meeting the requirements for wound coverage and effective delivery of BVT2733 BPs. In vitro studies demonstrated that the sustained release of BVT2733 from the scaffold promoted skin cell proliferation and migration while stimulating angiogenesis by upregulating HIF1-α/VEGF expression. The therapeutic effect of the scaffold was further confirmed in a full-thickness wound model using diabetic mice. The mice treated with the scaffolds exhibited an accelerated wound healing rate, increased neovascularization, enhanced collagen deposition, and regeneration of skin appendages within 2 weeks postinjury. The findings here provide evidence for the use of 11β-HSD1 inhibitor-integrated biomaterials in treating DUs and represent a novel biological platform for modulating dysregulated mechanisms in DUs.

Development of silk microfiber-reinforced bioink for muscle tissue engineering and in situ printing by a handheld 3D printer

Volumetric muscle loss (VML) presents a significant challenge in tissue engineering due to the irreparable nature of extensive muscle injuries. In this study, we propose a novel approach for VML treatment using a bioink composed of silk microfiber-reinforced silk fibroin (SF) hydrogel. The engineered scaffolds are predesigned to provide structural support and fiber alignment to promote tissue regeneration in situ. We also validated our custom-made handheld 3D printer performance and showcased its potential applications for in situ printing using robotics. The fiber contents of SF and gelatin ink were varied from 1 to 5 %. Silk fibroin microfibers reinforced ink offered increased viscosity of the gel, which enhanced the shape fidelity and mechanical strength of the bulk scaffold. The fiber-reinforced bioink also demonstrated better cell-biomaterial interaction upon printing. The handheld 3D printer enabled the precise and on-demand fabrication of scaffolds directly at the defect site, for personalized and minimally invasive treatment. This innovative approach holds promise for addressing the challenges associated with VML treatment and advancing the field of regenerative medicine.

Structural and sorption characteristics of an aerogel composite material loaded with flufenamic acid: insights from MAS NMR and high-pressure NOESY studies

The structural and sorption characteristics of a composite material consisting of a silica aerogel loaded with flufenamic acid were investigated using a variety of nuclear magnetic resonance techniques. The composite structure was analyzed using magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, which revealed significant interactions between the aerogel matrix and the FFA molecules. Solid-state 29Si NMR provided insights into the aerogel's stability, while 1H and 13C NMR confirmed the presence of FFA in the matrix, with signals from FFA molecules observed alongside tetraethoxysilane (TEOS) groups. Ethanol-induced desorption of FFA led to narrowed spectral lines, suggesting the breaking of intermolecular hydrogen bonds. 19F MAS NMR spectra indicated changes in FFA local environments upon loading into AG pores. Evaluation of CO2 sorption characteristics using 13C NMR demonstrated a slower sorption rate for AG + FFA than that for pure AG, attributed to decreased pore volume. Furthermore, nuclear Overhauser effect spectroscopy (NOESY) was employed to explore the conformational behavior of FFA within the aerogel matrix. The results indicated a shift in conformer populations, particularly those related to the rotation of one cyclic fragment relative to the other. These findings provide insights into the structural and sorption characteristics of the AG + FFA composite, which are valuable for developing novel drug solid forms.

Strategies in Electrospun Polymer and Hybrid Scaffolds for Enhanced Cell Integration and Vascularization for Bone Tissue Engineering and Organoids

Addressing the demand for bone substitutes, tissue engineering responds to the high prevalence of orthopedic surgeries worldwide and the limitations of conventional tissue reconstruction techniques. Materials, cells, and growth factors constitute the core elements in bone tissue engineering, influencing cellular behavior crucial for regenerative treatments. Scaffold design, including architectural features and porosity, significantly impacts cellular penetration, proliferation, differentiation, and vascularization. This review discusses the hierarchical structure of bone and the process of neovascularization in the context of biofabrication of scaffolds. We focus on the role of electrospinning and its modifications in scaffold fabrication to improve scaffold properties to enhance further tissue regeneration, for example, by boosting oxygen and nutrient delivery. We highlight how scaffold design impacts osteogenesis and the overall success of regenerative treatments by mimicking the extracellular matrix (ECM). Additionally, we explore the emerging field of bone organoids-self-assembled, three-dimensional (3D) structures derived from stem cells that replicate native bone tissue's architecture and functionality. While bone organoids hold immense potential for modeling bone diseases and facilitating regenerative treatments, their main limitation remains insufficient vascularization. Hence, we evaluate innovative strategies for pre-vascularization and discuss the latest techniques for assessing and improving vascularization in both scaffolds and organoids presenting the most commonly used cell lines and biological models. Moreover, we analyze cutting-edge techniques for assessing vascularization, evaluating their advantages and drawbacks to propose complex solutions. Finally, by integrating these approaches, we aim to advance the development of bioactive materials that promote successful bone regeneration.

Granular Porous Nanofibrous Microspheres Enhance Cellular Infiltration for Diabetic Wound Healing

Diabetic foot ulcers (DFUs) are a significant challenge in the clinical care of diabetic patients, often necessitating limb amputation and compromising the quality of life and life expectancy of this cohort. Minimally invasive therapies, such as modular scaffolds, are at the forefront of current DFU treatment, offering an efficient approach for administering therapeutics that accelerate tissue repair and regeneration. In this study, we report a facile method for fabricating granular nanofibrous microspheres (NMs) with predesigned structures and porosities. The proposed technology combines electrospinning and electrospraying to develop a therapeutic option for DFUs. Specifically, porous NMs were constructed using electrospun poly(lactic-co-glycolic acid) (PLGA):gelatin short nanofibers, followed by gelatin cross-linking. These NMs demonstrated enhanced cell adhesion to human dermal fibroblasts (HDF) during an in vitro cytocompatibility assessment. Notably, porous NMs displayed superior performance owing to their interconnected pores compared to nonporous NMs. Cell-laden NMs demonstrated higher Young's modulus values than NMs without loaded cells, suggesting improved material resiliency attributed to the reinforcement of cells and their secreted extracellular matrix. Dynamic injection studies on cell-laden NMs further elucidated their capacity to safeguard loaded cells under pressure. In addition, porous NMs promoted host cell infiltration, neovascularization, and re-epithelialization in a diabetic mouse wound model, signifying their effectiveness in healing diabetic wounds. Taken together, porous NMs hold significant potential as minimally invasive, injectable treatments that effectively promote tissue integration and regeneration.

Synthetic Extracellular Matrix of Polyvinyl Alcohol Nanofibers for Three-Dimensional Cell Culture

An ideal extracellular matrix (ECM) replacement scaffold in a three-dimensional cell (3D) culture should induce in vivo-like interactions between the ECM and cultured cells. Highly hydrophilic polyvinyl alcohol (PVA) nanofibers disintegrate upon contact with water, resulting in the loss of their fibrous morphology in cell cultures. This can be resolved by using chemical crosslinkers and post-crosslinking. A crosslinked, water-stable, porous, and optically transparent PVA nanofibrous membrane (NM) supports the 3D growth of various cell types. The binding of cells attached to the porous PVA NM is low, resulting in the aggregation of cultured cells in prolonged cultures. PVA NMs containing integrin-binding peptides of fibronectin and laminin were produced to retain the blended peptides as cell-binding substrates. These peptide-blended PVA NMs promote peptide-specific cell adherence and growth. Various cells, including epithelial cells, cultured on these PVA NMs form layers instead of cell aggregates and spheroids, and their growth patterns are similar to those of the cells cultured on an ECM-coated PVA NM. The peptide-retained PVA NMs are non-stimulatory to dendritic cells cultured on the membranes. These peptide-retaining PVA NMs can be used as an ECM replacement matrix by providing in vivo-like interactions between the matrix and cultured cells.