Nanofibered Gelatin-Based Nonwoven Elasticity Promotes Epithelial Histogenesis

Restoration of Pregnancy Function Using a GT/PCL Biofilm in a Rabbit Model of Uterine Injury

Biomaterial scaffolds have been used successfully to promote the regenerative repair of small endometrial lesions in small rodents, providing partial restoration of gestational function. The use of rabbits in this study allowed us to investigate a larger endometrial tissue defect and myometrial injury model. A gelatin/polycaprolactone (GT/PCL) gradient-layer biofilm was sutured at the defect to guide the reconstruction of the original tissue structure. Twenty-eight days postimplantation, the uterine cavity had been restored to its original morphology, endometrial growth was accompanied by the formation of glands and blood vessels, and the fragmented myofibers of the uterine smooth muscle had begun to resemble the normal structure of the lagomorph uterine cavity, arranging in a circular luminal pattern and a longitudinal serosal pattern. In addition, the repair site supported both embryonic implantation into the placenta and normal embryonic development. Four-dimensional label-free proteomic analysis identified the cell adhesion molecules, phagosome, ferroptosis, rap1 signaling pathways, hematopoietic cell lineage, complement and coagulation cascades, tricarboxylic acid cycle, carbon metabolism, and hypoxia inducible factor (HIF)-1 signaling pathways as important in the endogenous repair process of uterine tissue injury, and acetylation of protein modification sites upregulated these signaling pathways.

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

Fibroblasts and polymer composition are essential for bioengineering of airway epithelium on nonwoven scaffolds

To make tissue engineering a truly effective tool, it is necessary to understand how the patterns of specific tissue development are modulated by and depend on the artificial environment. Even the most advanced approaches still do not fully meet the requirements of practical engineering of tracheobronchial epithelium. This study aimed to test the ability of the synthetic and natural nonwoven scaffolds to support the formation of morphological sound airway epithelium including the basement membrane (BM). We also sought to identify the potential role of fibroblasts in this process. Our results showed that nonwoven scaffolds are generally suitable for producing well-differentiated tracheobronchial epithelium (with cilia and goblet cells), while the structure and functionality of the equivalents appeared to be highly dependent on the composition of the scaffolds. Unlike natural scaffolds, synthetic ones supported the formation of the epithelium only when epithelial cells were cocultured with fibroblasts. Fibroblasts also appeared to be obligatory for basal lamina formation, regardless of the type of the nonwoven material used. However, even in the presence of fibroblasts, the synthetic scaffolds were unable to support the formation of the epithelium and of the BM (in particular, basal lamina) as effectively as the natural scaffolds did.

Overview of Tissue Engineering and Drug Delivery Applications of Reactive Electrospinning and Crosslinking Techniques of Polymeric Nanofibers with Highlights on Their Biocompatibility Testing and Regulatory Aspects

Traditional electrospinning is a promising technique for fabricating nanofibers for tissue engineering and drug delivery applications. The method is highly efficient in producing nanofibers with morphology and porosity similar to the extracellular matrix. Nonetheless, and in many instances, the process has faced several limitations, including weak mechanical strength, large diameter distributions, and scaling-up difficulties of its fabricated electrospun nanofibers. The constraints of the polymer solution's intrinsic properties are primarily responsible for these limitations. Reactive electrospinning constitutes a novel and modified electrospinning techniques developed to overcome those challenges and improve the properties of the fabricated fibers intended for various biomedical applications. This review mainly addresses reactive electrospinning techniques, a relatively new approach for making in situ or post-crosslinked nanofibers. It provides an overview of and discusses the recent literature about chemical and photoreactive electrospinning, their various techniques, their biomedical applications, and FDA regulatory aspects related to their approval and marketing. Another aspect highlighted in this review is the use of crosslinking and reactive electrospinning techniques to enhance the fabricated nanofibers' physicochemical and mechanical properties and make them more biocompatible and tailored for advanced intelligent drug delivery and tissue engineering applications.

Current Status of Tissue Regenerative Engineering for the Treatment of Uterine Infertility

With the recent developments in tissue engineering, scientists have attempted to establish seed cells from different sources, create cell sheets through various technologies, implant them on scaffolds with various spatial structures, or load scaffolds with cytokines. These research results are very optimistic, bringing hope to the treatment of patients with uterine infertility. In this article, we reviewed articles related to the treatment of uterine infertility from the aspects of experimental treatment strategy, seed cells, scaffold application, and repair criteria so as to provide a basis for future research.

Novel In Situ-Cross-Linked Electrospun Gelatin/Hydroxyapatite Nonwoven Scaffolds Prove Suitable for Periodontal Tissue Engineering

Periodontal diseases affect millions of people worldwide and can result in tooth loss. Regenerative treatment options for clinical use are thus needed. We aimed at developing new nonwoven-based scaffolds for periodontal tissue engineering. Nonwovens of 16% gelatin/5% hydroxyapatite were produced by electrospinning and in situ glyoxal cross-linking. In a subset of scaffolds, additional porosity was incorporated via extractable polyethylene glycol fibers. Cell colonization and penetration by human mesenchymal stem cells (hMSCs), periodontal ligament fibroblasts (PDLFs), or cocultures of both were visualized by scanning electron microscopy and 4′,6-diamidin-2-phenylindole (DAPI) staining. Metabolic activity was assessed via Alamar Blue^® staining. Cell type and differentiation were analyzed by immunocytochemical staining of Oct4, osteopontin, and periostin. The electrospun nonwovens were efficiently populated by both hMSCs and PDLFs, while scaffolds with additional porosity harbored significantly more cells. The metabolic activity was higher for cocultures of hMSCs and PDLFs, or for PDLF-seeded scaffolds. Periostin and osteopontin expression was more pronounced in cocultures of hMSCs and PDLFs, whereas Oct4 staining was limited to hMSCs. These novel in situ-cross-linked electrospun nonwoven scaffolds allow for efficient adhesion and survival of hMSCs and PDLFs. Coordinated expression of differentiation markers was observed, which rendered this platform an interesting candidate for periodontal tissue engineering.

Molecular Research on Oral Diseases and Related Biomaterials: A Journey from Oral Cell Models to Advanced Regenerative Perspectives

Oral diseases such as gingivitis, periodontitis, and oral cancer affect millions of people worldwide. Much research has been conducted to understand the pathogenetic mechanisms of these diseases and translate this knowledge into therapeutics. This review aims to take the reader on a journey from the initial molecular discoveries to complex regenerative issues in oral medicine. For this, a semi-systematic literature search was carried out in Medline and Web of Science databases to retrieve the primary literature describing oral cell models and biomaterial applications in oral regenerative medicine. First, an in vitro cell model of gingival keratinocytes is discussed, which illustrates patho- and physiologic principles in the context of oral epithelial homeostasis and carcinogenesis and represents a cellular tool to understand biomaterial-based approaches for periodontal tissue regeneration. Consequently, a layered gradient nonwoven (LGN) is described, which demonstrates that the key features of biomaterials serve as candidates for oral tissue regeneration. LGN supports proper tissue formation and obeys the important principles for molecular mechanotransduction. Furthermore, current biomaterial-based tissue regeneration trends, including polymer modifications, cell-based treatments, antimicrobial peptides and optogenetics, are introduced to represent the full spectrum of current approaches to oral disease mitigation and prevention. Altogether, this review is a foray through established and new concepts in oral regenerative medicine and illustrates the process of knowledge translation from basic molecular and cell biological research to future clinical applications.

Biodegraded PCl and gelatin fabricated vascular patch in rat aortic and inferior vena cava angioplasty

Novel synthetic prosthesis materials for patch angioplasty are continuously under development and optimization. When a nonwoven-based gelatin membrane is coupled with an electrospun layer of polycaprolactone (PCL), these biohybrid polymer membranes (BHMs) possess higher mechanical properties in aqueous environments. We hypothesized that BHMs can also be used as vascular patches, and we tested our hypothesis in a rat IVC venoplasty and aortic arterioplasty model. Patch venoplasty and arterioplasty were performed in SD rats (200 g), the patches were harvested at day 14, and samples were analyzed by immunohistochemistry and immunofluorescence. The BHM patches were almost degraded, with few parts remaining after 14 days. There was a line of CD34- and nestin-positive cells on the endothelium, with some cells were CD34 and nestin dual-positive, macrophages and leukocytes also participated in the patch healing process. There were PCNA-positive cells in the neointima and peri-patch area, with some cells were also PCNA and α-actin dual-positive. Arterial neointimal endothelial cells were Ephrin-B2- and dll-4-positive, and venous neointimal endothelial cells were Eph-B4- and COUP-TFII-positive. BHM shares a similar healing process like other patch materials, and BHM may have potential applications in vascular surgery.

The effect of modifying the nanostructure of gelatin fiber scaffolds on early angiogenesisin vitroandin vivo

Early angiogenesis is one of the key challenges in tissue regeneration. Crosslinking mode and fiber diameter are critical factors to affect the adhesion and proliferation of cells. However, whether and how these two factors affect early angiogenesis remain largely unknown. To address the issue, the optimal crosslinking mode and fiber diameter of gelatin fiber membrane for early angiogenesisin vivoandin vitrowere explored in this work. Compared with the post crosslinked gelatin fiber membrane with the same fiber diameter, the 700 nm diameterin situcrosslinked gelatin fiber membrane was found to have smaller roughness (230.67 ± 19 nm) and stronger hydrophilicity (54.77° ± 1.2°), which were suitable for cell growth and adhesion. Moreover, thein situcrosslinked gelatin fiber membrane with a fiber diameter of 1000 nm had significant advantages in early angiogenesis over the two with fiber diameters of 500 and 700 nm by up-regulating the expression of Ang1, VEGF, and integrin-β1. Our findings indicated that thein situcrosslinked gelatin fiber membrane with a diameter of 1000 nm might solve the problem of insufficient blood supply in the early stage of soft tissue regeneration and has broad clinical application prospects in promoting tissue regeneration.

FAK Shutdown: Consequences on Epithelial Morphogenesis and Biomarker Expression Involving an Innovative Biomaterial for Tissue Regeneration

By employing an innovative biohybrid membrane, the present study aimed at elucidating the mechanistic role of the focal adhesion kinase (FAK) in epithelial morphogenesis in vitro over 4, 7, and 10 days. The consequences of siRNA-mediated FAK knockdown on epithelial morphogenesis were monitored by quantifying cell layers and detecting the expression of biomarkers of epithelial differentiation and homeostasis. Histologic examination of FAK-depleted samples showed a significant increase in cell layers resembling epithelial hyperplasia. Semiquantitative fluorescence imaging (SQFI) revealed tissue homeostatic disturbances by significantly increased involucrin expression over time, persistence of yes-associated protein (YAP) and an increase of keratin (K) 1 at day 4. The dysbalanced involucrin pattern was underscored by ROCK-II^Ser1366 activity at day 7 and 10. SQFI data were confirmed by quantitative PCR and Western blot analysis, thereby corroborating the FAK shutdown-related expression changes. The artificial FAK shutdown was also associated with a significantly higher expression of filaggrin at day 10, sustained keratinocyte proliferation, and the dysregulated expression of K19 and vimentin. These siRNA-induced consequences indicate the mechanistic role of FAK in epithelial morphogenesis by simultaneously considering prospective biomaterial-based epithelial regenerative approaches.

Inducing Immunomodulatory Effects on Human Macrophages by Multifunctional NCO-sP(EO-stat-PO)/Gelatin Hydrogel Nanofibers

Endowing materials and scaffolds with immunomodulatory properties has evolved into a very active field of research. However, combining such effects with multifunctionality regarding cell adhesion and manipulation is still challenging due to the intricate nature of cell-substrate interactions that require fine-tuning of scaffold properties. Here, we reported electrospinning of a well-known biopolymer, gelatin, together with six-arm star-shaped poly(ethylene oxide-stat-propylene oxide) prepolymer with isocyanate end groups (NCO-sP(EO-stat-PO)) as a reactive prepolymer cross-linker. Covalent coupling of two components during and after processing yielded a network of hydrogel fibers that was remarkably stable under aqueous and also proteolytic conditions without the need for extra cross-linking, with a significant increase in stability with increasing NCO-sP(EO-stat-PO) content. When seeded with human macrophages, cells adhered and spread on the fibers and were found highly viable after 7 days of culture across all scaffolds. Furthermore, hybrid fibrous meshes upregulated the expression of a prohealing gene, CD206, while downregulating proinflammatory genes, IL-1β and IL-8. Markedly, NCO-sP(EO-stat-PO)-rich samples induced a significantly reduced release of proinflammatory cytokines, IL-1β, IL-6, and IL-8. Finally, we successfully conjugated IL-4 to NCO-sP(EO-stat-PO) that effectively steered macrophages into a prohealing M2 type, demonstrating additional and robust control over the immunomodulatory feature of the scaffolds.

From the Matrix to the Nucleus and Back: Mechanobiology in the Light of Health, Pathologies, and Regeneration of Oral Periodontal Tissues

Among oral tissues, the periodontium is permanently subjected to mechanical forces resulting from chewing, mastication, or orthodontic appliances. Molecularly, these movements induce a series of subsequent signaling processes, which are embedded in the biological concept of cellular mechanotransduction (MT). Cell and tissue structures, ranging from the extracellular matrix (ECM) to the plasma membrane, the cytosol and the nucleus, are involved in MT. Dysregulation of the diverse, fine-tuned interaction of molecular players responsible for transmitting biophysical environmental information into the cell's inner milieu can lead to and promote serious diseases, such as periodontitis or oral squamous cell carcinoma (OSCC). Therefore, periodontal integrity and regeneration is highly dependent on the proper integration and regulation of mechanobiological signals in the context of cell behavior. Recent experimental findings have increased the understanding of classical cellular mechanosensing mechanisms by both integrating exogenic factors such as bacterial gingipain proteases and newly discovered cell-inherent functions of mechanoresponsive co-transcriptional regulators such as the Yes-associated protein 1 (YAP1) or the nuclear cytoskeleton. Regarding periodontal MT research, this review offers insights into the current trends and open aspects. Concerning oral regenerative medicine or weakening of periodontal tissue diseases, perspectives on future applications of mechanobiological principles are discussed.

In vitro biocompatibility of biohybrid polymers membrane evaluated in human gingival fibroblasts

The biohybrid polymer membrane (BHM) is a new biomaterial designed for the treatment of soft periodontal tissue defects. We aimed to evaluate the in vitro biocompatibility of the membrane in human gingival fibroblasts and the capability to induce cell adhesion, migration, differentiation and improving the production of the extracellular matrix. BHM and Mucograft® collagen matrix (MCM) membranes were punched into 6 mm diameter round discs and placed in 96‐well plates. Human primary gingival fibroblasts were seeded on the membranes or tissue culture plastic (TCP) serving as the control. Cell proliferation/viability and morphology were evaluated after 3, 7, and 14 days of culture by cell counting kit (CCK)‐8 assay and scanning electron microscopy, respectively. Additionally, the gene expression of transforming growth factor (TGF)‐β1, focal adhesion kinase (FAK), collagen type 1 (Col1), alpha‐smooth muscle actin (α‐SMA), and fibroblasts growth factor (FGF)‐2 was analyzed at 3, 7, and 14 days of culture by qPCR. Cell proliferation on BHM was significantly higher than on MCM and similar to TCP. Gene expression of TGF‐β1, FAK, Col1, and α‐SMA were significantly increased on BHM compared to TCP at most investigated time points. However, the gene expression of FGF‐2 was significantly decreased on BHM at Day 7 and recovered at Day 14 to the levels similar to TCP. The finding of this study showed that BHM is superior for gingival fibroblasts in terms of adhesion, proliferation, and gene expression, suggesting that this membrane may promote the healing of soft periodontal tissue.

Nonwoven membranes for tissue engineering: an overview of cartilage, epithelium, and bone regeneration

Scaffold-type biomaterials are crucial for application in tissue engineering. Among them, the use of a nonwoven scaffold has grown in recent years and has been widely investigated for the regeneration of different types of tissues. Several polymers, whether they are synthetic, biopolymers or both, have been used to produce a scaffold that can mimic the natural tissue to which it will be applied to. The scaffolds used in tissue engineering must be biocompatible and allow cell adhesion and proliferation to be applied in tissue engineering. In addition, the scaffolds should maintain the mechanical properties and architecture of the desired tissue. Nonwoven fabrics have produced good results and are more extensively applied for the regeneration of cartilage, epithelial and bone tissues. Recent advances in tissue engineering have shown promising results, however, no ideal material or standardization parameters and characteristics of the materials were obtained. The present review provides an overview of the application of nonwoven scaffolds, including the main results obtained regarding the properties of the biomaterials and their applications in vitro and in vivo, focusing on the cartilaginous, the epithelium, and bone tissue regeneration.

In vivo evaluation of an electrospun gelatin nonwoven mat for regeneration of epithelial tissues

One major objective in epithelial tissue engineering is to identify a suitable biomaterial that supports epithelial tissue formation. Therefore, the purpose of this study is to elucidate a novel electrospun gelatin nonwoven mat (NWM) for epithelial tissue engineering purposes in vivo. This NWM was seeded with either human gingival keratinocytes (GK, in coculture with gingival fibroblast) or human skin epithelial keratinocytes (EK, in coculture with skin dermal fibroblasts). These constructs were ex vivo cultured for 4 days before subcutaneous implantation into athymic nude mice. After 7 days, the constructs were explanted and investigated by immunohistology. Our results show that GK form a stratified epithelium on the surface of the NWM, mostly independent of a fibroblastic counterpart. Like native mucosa, the regenerated epithelium showed expression of epidermal growth factor receptor, cytokeratin-14 and -1, and involucrin. Only the expression of the basement membrane constituent laminin 5 was more pronounced in cocultures. Comparing GK and skin EK, we found that skin EK form a less developed epithelial tissue. Furthermore, the NWM allows not only for epithelial tissue formation by GK, but also for infiltration of human fibroblasts and mouse immune cells, thus representing a biomaterial with potential regenerative capacity for oral mucosa tissue engineering applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1605-1614, 2019.

Gelatin nonwovens-based epithelial morphogenesis involves a signaling axis comprising EGF-receptor, MAP kinases ERK 1/2, and β1 integrin

In biomaterials research, biomechanics which support tissue regeneration steadily gains of importance. Hence, we have previously shown that gelatin-based electrospun nonwoven mats (NWMs) with a distinct modulus of elasticity (3.2 kPa) promotes epithelial morphogenesis. Since molecular mechanisms of this morphogenesis are still unknown, the present study aims at identifying molecules, involved herein. Epithelia established on the NMWs showed persistence of the activated state of the epidermal growth factor receptor (EGF-R), phosphorylated at the src-specific tyrosine 845 (EGF-R_T845 ) throughout the observation period of 10 days. To elucidate whether the observed morphogenesis mechanistically involves EGF-R signaling, we inhibited EGF-R, by employing the EGF-R_T845 specific inhibitor Gefitinib (IRESSA®). Gefitinib administration yielded a reduced expression of the β1 integrin subunit, a well-known cell-matrix interaction receptor, concomitant with downregulation of p42/44 ERK1/2 MAP-kinase activity. To elucidate whether the observed downregulation of β1 is EGF-R_T845 -dependent or emerging from ERK1/2 signaling, we exposed epithelia, grown on the NWMs, with the ERK1/2-directed inhibitor U0126. In the absence of Gefitinib, inhibition of p42/44 MAP-kinase activity resulted in decreased β1 integrin protein levels, thus indicating that β1 expression is dependent on ERK1/2 and not EGF-R_T845 . Our results showed the first time that an EGF-R-β1 integrin-signaling axis, including ERK1/2, promotes NWM-elasticity-based epithelial morphogenesis. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 663-677, 2019.