Tissue Regeneration Applications Research Articles

Hydroxyapatite/Chondroitin Sulphate Nanocomposite Infused with Black Seed Oil for Bone Tissue Applications: Physicochemical Characterizations and In Vitro Screening

AbstractMorbidities associated with natural bone have highlighted the need of advanced bioactive implants for the replacement of damaged bone. Known for their beneficial bioactivity and biocompatibility, Nigella sativa seeds (kalonji/black seed) are traditionally used in many medications. This research focuses on the positive impact of black seed extract on the chondroitin sulfate‐based hydroxyapatite nanocomposite for bone tissue regeneration applications. Novel nanocomposites with varied concentrations of black seed extract (0, 1, 2, and 3 wt%) were fabricated through a coprecipitation approach and analyzed for physicochemical and biological applications. The results of X‐ray diffraction and FTIR spectroscopy revealed that the HCSK3 nanocomposite was successfully developed with appreciably strong molecular interactions among their components. HCSK3 nanocomposite exhibits higher rough surface morphology (Ra −1.13 µm and Rz −4.8 µm), uniform particle distribution (average particle size −9.9 nm), and good thermal stability with total weight loss of 13%. It also provides better nucleation sites for apatite formation and protein adsorption stimulating cell attachment, proliferation, and differentiation. Moreover, HCSK3 nanocomposite showed excellent cell viability, higher ARS/ALP activities, better antibacterial property, and nonhemolytic property (below 3%). Thus, it can be concluded that HCSK3 nanocomposite manifested the highest biocompatibility and negligible cell toxicity. Therefore, it can be employed as an ideal bone implant in the bone tissue restoration phenomenon.

Simple and Cost-Effective Generation of 3D Cell Sheets and Spheroids Using Curvature-Controlled Paraffin Wax Substrates

The challenges associated with animal testing in pharmaceutical development have driven the search for alternative in vitro models that mimic human tissues more accurately. In this study, we present a simple and cost-effective method for generating 3D cell sheets and spheroids using curvature-controlled paraffin wax films, which are easily accessible laboratory materials that eliminate the need for extracellular matrix (ECM) components or thermo-responsive polymers. By adjusting the curvature of the paraffin wax film, we successfully generated human periodontal ligament fibroblast (HPdLF) cell sheets and bone marrow-derived mesenchymal stem cell (hBMSC) spheroids. Key parameters, such as cell density, substrate curvature, and incubation time, were identified as critical factors for optimizing the formation of these 3D structures. In addition, the use of quantum dots (QDs) for cell tracking enabled long-term visualization and distinction between different cell types within complex tissue-like structures. We further demonstrated that wrapping the hBMSC spheroids with HPdLF cell sheets partially replicated the connective tissue structure of the periodontal ligament surrounding the tooth root. This highlights the potential of this platform for the construction of more sophisticated tissue-mimicking assemblies. In conclusion, curvature-controlled paraffin wax films provide a versatile and practical approach for 3D cell cultures. This simplifies the generation of both cell sheets and spheroids, offering a promising tool for tissue engineering and regenerative medicine applications, where precise cell-to-cell interactions are essential.Graphical abstract

Gelatin-Based Polymers Can Be Processed to Highly Resilient Biocompatible Porous Hydrogel Scaffolds for Soft Tissue Regeneration Applications.

Tissue regeneration relies on the mechanical properties of the surrounding environment, and it has already been shown that mechanostimulation is highly dependent on the stiffness of the native biological tissue. The main advantage of injectable hydrogels in medical applications is their ability to be delivered through minimally invasive techniques. Natural polymer-based hydrogels have been widely used in biomedical applications, due to their high biocompatibility, low immunogenicity, and similarity to soft tissues. However, the crucial combination of low stiffness with high resilience has not been achieved for natural polymers. The current study focuses on the development of novel gelatin-based injectable hydrogels for soft tissue regeneration applications, elucidating the effects of the formulation parameters on the resilience, microstructure, biocompatibility, and mechanical properties. Non-foamed hydrogels demonstrated resilience of at least 95%, while porous hydrogels maintained resilience above 90%, allowing them to withstand mechanical stresses and dynamic conditions within the body. The adjustable modulus of these hydrogels provides the necessary flexibility to mimic the mechanical properties of soft and very soft tissues, without compromising resilience. Environmental Scanning Electron Microscopy (ESEM) observations of the porous hydrogels indicated round interconnected pore structures, desired for cell migration and nutrient flow. Biocompatibility tests on fibroblasts and pre-adipocytes confirmed high biocompatibility, both directly and indirectly. In summary, structuring these new hydrogels for achieving adjustable stiffness, along with the excellent resilience and biocompatibility, is expected to enable this new technology to fit various soft tissue regeneration applications.

Quercetin ameliorates senescence and promotes osteogenesis of BMSCs by suppressing the repetitive element‑triggered RNA sensing pathway.

Cell senescence impedes the self‑renewal and osteogenic capacity of bone marrow mesenchymal stem cells (BMSCs), thus limiting their application in tissue regeneration. The present study aimed to elucidate the role and mechanism of repetitive element (RE) activation in BMSC senescence and osteogenesis, as well as the intervention effect of quercetin. In an H2O2‑induced BMSC senescence model, quercetin treatment alleviated senescence as shown by a decrease in senescence‑associated β‑galactosidase (SA‑β‑gal)‑positive cell ratio, increased colony formation ability and decreased mRNA expression of p21 and senescence‑associated secretory phenotype genes. DNA damage response marker γ‑H2AX increased in senescent BMSCs, while expression of epigenetic markers methylation histone H3 Lys9, heterochromatin protein 1α and heterochromatin‑related nuclear membrane protein lamina‑associated polypeptide 2 decreased. Quercetin rescued these alterations, indicating its ability to ameliorate senescence by stabilizing heterochromatin structure where REs are primarily suppressed. Transcriptional activation of REs accompanied by accumulation of cytoplasmic double‑stranded (ds)RNA, as well as triggering of the RNA sensor retinoic acid‑inducible gene I (RIG‑I) receptor pathway in H2O2‑induced senescent BMSCs were shown. Similarly, quercetin treatment inhibited these responses. Additionally, RIG‑I knockdown led to a decreased number of SA‑β‑gal‑positive cells, confirming its functional impact on senescence. Induction of senescence or administration of dsRNA analogue significantly hindered the osteogenic capacity of BMSCs, while quercetin treatment or RIG‑I knockdown reversed the decline in osteogenic function. The findings of the current study demonstrated that quercetin inhibited the activation of REs and the RIG‑I RNA sensing pathway via epigenetic regulation, thereby alleviating the senescence of BMSCs and promoting osteogenesis.

The Effect of Carbodiimide Crosslinkers on Gelatin Hydrogel as a Potential Biomaterial for Gingival Tissue Regeneration.

Connective tissue grafts for gingival recession treatment present significant challenges as they require an additional surgical site, leading to increased morbidity, extended operative times, and a more painful postoperative recovery for patients. Gelatin contains the arginine-glycine-aspartic acid (RGD) sequence, which supports cell adhesion and interactions. The development of gelatin hydrogels holds significant promise due to their biocompatibility, ease of customization, and structural resemblance to the extracellular matrix, making them a potential candidate for gingival regeneration. This study aimed to assess the physical and biological properties of crosslinked gelatin hydrogels using EDC/NHS with two crosslinker concentrations (GelCL12 and GelCL24) and compare these to non-crosslinked gelatin. Both groups underwent morphological, rheological, and chemical analysis. Biological assessments were conducted to evaluate human gingival fibroblast (HGF) proliferation, migration, and COL1 expression in response to the scaffolds. The crosslinked gelatin group exhibited greater interconnectivity and better physical characteristics without displaying cytotoxic effects on the cells. FTIR analysis revealed no significant chemical differences between the groups. Notably, the GelCL12 group significantly enhanced HGF migration and upregulated COL1 expression. Overall, GelCL12 met the required physical characteristics and biocompatibility, making it a promising scaffold for future gingival tissue regeneration applications.

Therapeutic potency of marine collagen/pectin scaffolds - Fabrication, characterization and evaluation

Skin is an important vital organ that must be given proper care and protection from external damage and harmful microbes. If injured, it must be treated with an ideal wound dressing material with potent hemostatic and non-toxic properties. In the present study, fish collagen (FC) was extracted from the fins and tails of Black pomfret (Parastromateus niger). The isolated fish collagen was homogenized with pectin (P) and freeze dried to obtain fish collagen/pectin (FC/P) scaffolds. Scanning electron microscopic analysis showed the porous nature of scaffolds with intermittent holes. UV–Visible and Fourier infrared spectroscopic analyses demonstrated the physicochemical properties of FC/P scaffolds. Hemolytic assay performed using human blood demonstrated the percentage of hemolysis as 0.5 %. In vitro blood clotting assay carried out to determine the hemostatic behaviour displayed the formation of blood clot within 60 s in the presence of FC/P scaffolds. 95 % of cells were viable with the highest concentration of FC/P scaffold used for MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Scratch wound assay demonstrated complete closure of wound in FC/P scaffold treated cells after 48 h of treatment. Chick embryo chorioallantoic membrane (CAM) assay showed the development of new blood vessels within 6 h of incubation with the FC/P scaffolds, thereby proving their angiogenic potency. These results indicate the potential use of FC/P scaffolds as effective biomaterials for tissue regenerative applications.

An In Vitro Macrophage Response Study of Silk Fibroin and Silk Fibroin/Nano-Hydroxyapatite Scaffolds for Tissue Regeneration Application.

In recent years, silk fibroin (SF) has been incorporated with low crystallinity nanohydroxyapatite (nHA) as a scaffold for various tissue regeneration applications due to the mechanical strength of SF and osteoconductive properties of nHA. However, currently, there is a lack of understanding of the immune response toward the degradation products of SF with nHA composite after implantation. It is known that particulate fragments from the degradation of a biomaterial can trigger an immune response. As the scaffold is made of degradable materials, the degradation products may contribute to the inflammation. Therefore, in this study, the effects of the enzymatic degradation of the SF/nHA scaffold on macrophage response were investigated in comparison to the control SF scaffold. Since the degradation products of a scaffold can influence macrophage polarization, it can be hypothesized that as the SF and SF/nHA scaffolds were degraded in vitro using protease XIV solution, the degradation products can contribute to the polarization of THP-1-derived macrophages from pro-inflammatory M1 to anti-inflammatory M2 phenotype. The results demonstrated that the initial (day 1) degradation products of the SF/nHA scaffold elicited a pro-inflammatory response, while the latter (day 24) degradation products of the SF/nHA scaffold elicited an anti-inflammatory response. Moreover, the degradation products from the SF scaffold elicited a higher anti-inflammatory response due to the faster degradation of the SF scaffold and a higher amino acid concentration in the degradation solution. Hence, this paper can help elucidate the contributory effects of the degradation products of SF and SF/nHA scaffolds on macrophage response and provide greater insights into designing silk-based biomaterials with tunable degradation rates that can modulate macrophage response for future tissue regeneration applications.

Hydroxyapatite layer evolution on silica-based (45S10P) bioactive glass-ceramic nanoparticles doped with Zn2+ ions: Augmentation of in vitro bioactivity, antibacterial activity and textural modification for bone regeneration

Zinc-incorporated bioactive glasses (BG) and bioactive glass-ceramic (BGC) nanoparticles (BGC-NPs) represent highly adaptable, biodegradable, and bioactive materials in tissue engineering and regenerative medicine. This study delves into the synthesis, characterization and biomedical implications of Zn2+ ions-doped 45S10P spherical BGC-NPs, employing analytical techniques and in vitro assays. The resulting (Zn2++ 45S10P) BGC-NPs, prepared using a modified Strober's method, exhibited spherical morphology with excellent dispersion, as verified by TEM, FE-SEM, and DLS analyses. XRD, FTIR, and FESEM analysis revealed an augmented hydroxyapatite (HAp) layer formation with increasing zinc content. Zeta potential analysis showcased a shift from negative to positive values after immersion in simulated body fluid (SBF), indicating the bioactive potential of the developed BGC-NPs. Hemocompatibility assays indicated the biocompatibility of all BGC-NPs, demonstrating minimal hemolytic effects with incorporating Zn2+ ions below a standard threshold (<5 % lysis). Further, the migration assay revealed the potentiality of the BGC-NPs to stimulate the migration of HeLa cells. Cell viability assays employing MG-63 osteoblast-like cells highlighted enhanced cell viability over time, underscoring their non-toxic nature and potential for tissue regeneration. Antibacterial assays displayed significant inhibitory effects against Gram-negative compared to Gram-positive bacteria, underscoring their potential for anti-infection applications. Overall, the results affirm the promising prospects of Zinc incorporation into 45S10P BGC-NPs for bone tissue regeneration applications.

Cryogenic 3D Printing of GelMA/Graphene Bioinks: Improved Mechanical Strength and Structural Properties for Tissue Engineering.

Tissue engineering aims to recreate natural cellular environments to facilitate tissue regeneration. Gelatin methacrylate (GelMA) is widely utilized for its biocompatibility, ability to support cell adhesion and proliferation, and adjustable mechanical characteristics. This study developed a GelMA and graphene bioink platform at concentrations of 1, 1.5, and 2 mg/mL to enhance scaffold properties for tissue engineering applications. Graphene was incorporated into GelMA matrices to improve mechanical strength and electrical conductivity of the bioinks. The compressive strength and thermal stability of the resulting GelMA/graphene scaffolds were assessed through DSC analysis and mechanical testing. Cytotoxicity assays were conducted to determine cell survival rates. Cryoprinting at -30°C was employed to preserve scaffold structure and function. The chorioallantoic membrane (CAM) assay was used to evaluate biocompatibility and angiogenic potential. The integration of graphene significantly amplified the compressive strength and thermal stability of GelMA scaffolds. Cytotoxicity assays indicated robust cell survival rates of 90%, confirming the biocompatibility of the developed materials. Cryoprinting effectively preserved scaffold integrity and functionality. The CAM assay validated the biocompatibility and angiogenic potential, demonstrating substantial vascularization upon scaffold implantation onto chick embryo CAM. Integrating graphene into GelMA hydrogels, coupled with low-temperature 3D printing, represents a potent strategy for enhancing scaffold fabrication. The resultant GelMA/graphene scaffolds exhibit superior mechanical properties, biocompatibility, and pro-vascularization capabilities, making them highly suitable for diverse tissue engineering and regenerative medicine applications.

Impact of Polydeoxyribonucleotides on the Morphology, Viability, and Osteogenic Differentiation of Gingiva-Derived Stem Cell Spheroids

Background and Objectives: Polydeoxyribonucleotides (PDRN), composed of DNA fragments derived from salmon DNA, is widely recognized for its regenerative properties. It has been extensively used in medical applications, such as dermatology and wound healing, due to its ability to enhance cellular metabolic activity, stimulate angiogenesis, and promote tissue regeneration. In the field of dentistry, PDRN has shown potential in promoting periodontal healing and bone regeneration. This study aims to investigate the effects of PDRN on the morphology, survival, and osteogenic differentiation of gingiva-derived stem cell spheroids, with a focus on its potential applications in tissue engineering and regenerative dentistry. Materials and Methods: Gingiva-derived mesenchymal stem cells were cultured and formed into spheroids using microwells. The cells were treated with varying concentrations of PDRN (0, 25, 50, 75, and 100 μg/mL) and cultivated in osteogenic media. Cell morphology was observed over seven days using an inverted microscope, and viability was assessed with Live/Dead Kit assays and Cell Counting Kit-8. Osteogenic differentiation was evaluated by measuring alkaline phosphatase activity and calcium deposition. The expression levels of osteogenic markers RUNX2 and COL1A1 were quantified using real-time polymerase chain reaction. RNA sequencing was performed to assess the gene expression profiles related to osteogenesis. Results: The results demonstrated that PDRN treatment had no significant effect on spheroid diameter or cellular viability during the observation period. However, a PDRN concentration of 75 μg/mL significantly enhanced calcium deposition by Day 14, suggesting increased mineralization. RUNX2 and COL1A1 mRNA expression levels varied with PDRN concentration, with the highest RUNX2 expression observed at 25 μg/mL and the highest COL1A1 expression at 75 μg/mL. RNA sequencing further confirmed the upregulation of genes involved in osteogenic differentiation, with enhanced expression of RUNX2 and COL1A1 in PDRN-treated gingiva-derived stem cell spheroids. Conclusions: In summary, PDRN did not significantly affect the viability or morphology of gingiva-derived stem cell spheroids but influenced their osteogenic differentiation and mineralization in a concentration-dependent manner. These findings suggest that PDRN may play a role in promoting osteogenic processes in tissue engineering and regenerative dentistry applications, with specific effects observed at different concentrations.

Directed Differentiation of Adipose-Derived Stem Cells Using Imprinted Cell-Like Topographies as a Growth Factor-Free Approach.

The influence of surface topography on stem cell behavior and differentiation has garnered significant attention in regenerative medicine and tissue engineering. The cell-imprinting method has been introduced as a promising approach to mimic the geometry and topography of cells. The cell-imprinted substrates are designed to replicate the topographies and dimensions of target cells, enabling tailored interactions that promote the differentiation of stem cells towards desired specialized cell types. In fact, by replicating the size and shape of cells, biomimetic substrates provide physical cues that profoundly impact stem cell differentiation. These cues play a pivotal role in directing cell morphology, cytoskeletal organization, and gene expression, ultimately influencing lineage commitment. The biomimetic substrates' ability to emulate the native cellular microenvironment supports the creation of platforms capable of steering stem cell fate with high precision. This review discusses the role of mechanical factors that impact stem cell fate. It also provides an overview of the design and fabrication principles of cell-imprinted substrates. Furthermore, the paper delves into the use of cell-imprinted polydimethylsiloxane (PDMS) substrates to direct adipose-derived stem cells (ADSCs) differentiation into a variety of specialized cells for tissue engineering and regenerative medicine applications. Additionally, the review discusses the limitations of cell-imprinted PDMS substrates and highlights the efforts made to overcome these limitations.

Preparation and properties of biphasic hydrogels with tunable microstructures

Biphasic hydrogels are one of the most important biomaterials in tissue engineering due to their ability to mimic the properties of extracellular matrix. However, the lack of quantitative researches on biphasic hydrogel systems hinder the precise construction of the necessary living conditions for different cells. This fundamental study focuses on a biphasic emulsion hydrogel system consisting of polyethylene glycol diacrylate (PEGDA) and gelatin methacryloyl (GelMA), emphasizing the importance of microstructure in determining the physicochemical properties of biphasic hydrogels. Our approach utilizes a water-in-water (W/W) emulsion system, which is easy to operate and requires no purification steps. By constructing the phase diagram of PEGDA/GelMA biphasic emulsions, we demonstrate that adjusting the volume fractions of the two components results in distinct microstructures, including droplet-based and bicontinuous forms. The composition of biphasic hydrogel significantly influences its mechanical properties, swelling behavior, and biodegradability. Furthermore, the excellent biocompatibility of PEGDA/GelMA biphasic hydrogel system was demonstrated. This study conducts a more in-depth and quantitative study of the PEGDA/GelMA biphasic system. making it a versatile platform for creating precisely biomimetic environments suitable for cell encapsulation and tissue regeneration applications.

Fabrication of Thymol-loaded Isabgol/Konjac Glucomannan-based Microporous Scaffolds with Enriched Antioxidant and Antibacterial Properties for Skin Tissue Engineering Applications.

An antioxidant, antibacterial, and biocompatible biomaterial is essential to repair skin wounds effectively. Here, we have employed two natural biopolymers, isabgol (ISAB) and konjac glucomannan (KGM), to prepare microporous scaffolds by freezing and lyophilization. The scaffolds are loaded with thymol (THY) to impart potent antioxidant and antibacterial activities. The physicochemical properties of the ISAB+KGM+THY scaffold, like porosity (41.8±2.4 %), swelling, and biodegradation, were optimal for tissue regeneration application. Compared to the control, ISAB+KGM+THY scaffolds promote attachment, migration, and proliferation of L929 fibroblasts. The antioxidant activity of the ISAB+KGM+THY scaffold was significantly improved after loading THY. This would protect the tissues from oxidative damage. The antibacterial activity of the ISAB+KGM+THY scaffold was significantly higher than that of the control, which would help prevent bacterial infection. The vascularization ability of the ISAB+KGM scaffold was not altered by incorporating THY in the ISAB+KGM scaffold. Therefore, a strong antioxidant, antibacterial, and biocompatible nature of the ISAB+KGM+THY scaffold could be useful for various biomedical applications.

Ionic release from bioactive SiO2-CaOCME/poly(tetrahydrofuran)/poly(caprolactone) hybrids drives human-bone marrow stromal cell osteogenic differentiation

This study demonstrates that dissolution products of inorganic/organic SiO2-CaOCME/PTHF/PCL-diCOOH hybrid (70S30CCME-CL) drive human bone marrow stromal cells (h-BMSCs) down an osteogenic pathway with the production of mineralised matrix. We investigated osteogenesis through combined analyses of mRNA dynamics for key markers and targeted staining of mineralised matrix. We demonstrate that h-BMSCs undergo accelerated differentiation in vitro in response to the 70S30CCME-CL ionic milieu, as compared to incubation with osteogenic media. Extracts from 70S30CCME-CL promote osteogenesis by inducing changes in cellular metabolic activity, promoting changes in cell morphology consistent with the osteogenic lineage, and by enhancing mineralisation of hydroxyapatite in the extracellular matrix. Additionally, our results show that 70S30CCME-CL hybrids prove sustained functional resilience by maintaining osteostimulatory effects despite cumulated dissolution cycles. In co-differentiation medium, 70S30CCME-CL ionic release can modulate signalling pathways associated with non-osteogenic functions, further supporting their potential for bone regeneration applications. Overall, our study provides compelling experimental evidence that the 70S30CCME-CL hybrid is a promising biomaterial for bone tissue regeneration applications.

Design of improved acellular fish skin as a promising scaffold for tissue regeneration applications

Decellularized marine tissues have been regarded as a desirable biomaterial because of their biological risk reduction, less religious constraints, and resemblance to mammalian tissues. The properties of these matrices can be improved by adding cross-linkers. In this study, after decellularization of the of Tilapia and Grass carp fish skin, a comparative study was conducted between them. Due to the higher abundance of collagen and glycosaminoglycans (GAGs) in Tilapia skin, it was selected for further study. In the next step, the cross-linking process was performed with three concentrations of 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/ N-Hydroxysuccinimide (EDC/NHS) and tannic acid cross-linkers. The MTT results showed that the cross-linked samples with low concentrations of EDC/NHS had higher biocompatibility compared to the cross-linked sample with high concentration of EDC/NHS, as well as all samples cross-linked with tannic acid. Mechanical and physical studies conducted on the skin of Tilapia fish showed that the 15 mM/7.5 mM concentration of EDC/NHS increased the mechanical and temperature strength and decreased the degradability and it did not influence cell attachment.In general, it was shown that different fish skins differ in terms of collagen and GAGs, and the optimal concentration of EDC cross-linker improves the mechanical and physical properties of the matrix derived from fish skin.

Studies on cytocompatibility of human dermal fibroblasts on carbon nanofiber nanoparticle-containing bioprinted constructs

Functional nanocomposite-based printable inks impart strength, mechanical stability, and bioactivity to the printed matrix due to the presence of nanomaterials or nanostructures. Carbonaceous nanomaterials are known to improve the electrical conductivity, osteoconductivity, mechanical, and thermal properties of printed materials. In the current work, we have incorporated carbon nanofiber nanoparticles (CNF NPs) into methacrylated gelatin (GelMA) to investigate whether the resulting nanocomposite printable ink constructs (GelMA-CNF NPs) promote cell proliferation. Two kinds of printable constructs, cell-laden bioink and biomaterial ink, were prepared by incorporating various concentrations of CNF NPs (50, 100, and 150 µg/mL). The CNF NPs improved the mechanical strength and dielectric properties of the printed constructs. The in vitro cell line studies using normal human dermal fibroblasts (nHDF) demonstrated that CNF NPs are involved in cell-material interaction without affecting cellular morphology. Though the presence of NPs did not affect cellular viability on the initial days of treatment, it caused cytotoxicity to the cells on days 4 and 7 of the treatment. A significant level of cytotoxicity was observed in the highly CNF-concentrated bioink scaffolds (100 and 150 µg/mL). The unfavorable outcomes of the current work necessitate further study of employing functionalized CNF NPs to achieve enhanced cell proliferation in GelMA-CNF NPs-based bioprinted constructs and advance the application of skin tissue regeneration.Graphical abstract

Methods to achieve tissue-mimetic physicochemical properties in hydrogels for regenerative medicine and tissue engineering.

Hydrogels are water-swollen polymeric matrices with properties that are remarkably similar in function to the extracellular matrix. For example, the polymer matrix provides structural support and adhesion sites for cells in much of the same way as the fibers of the extracellular matrix. In addition, depending on the polymer used, bioactive sites on the polymer may provide signals to initiate certain cell behavior. However, despite their potential as biomaterials for tissue engineering and regenerative medicine applications, fabricating hydrogels that truly mimic the physicochemical properties of the extracellular matrix to physiologically-relevant values is a challenge. Recent efforts in the field have sought to improve the physicochemical properties of hydrogels using advanced materials science and engineering methods. In this review, we highlight some of the most promising methods, including crosslinking strategies and manufacturing approaches such as 3D bioprinting and granular hydrogels. We also provide a brief perspective on the future outlook of this field and how these methods may lead to the clinical translation of hydrogel biomaterials for tissue engineering and regenerative medicine applications.

Eco-friendly development of intrinsically antibacterial and mechanically robust self-healing hydrogels using alginate and oval proteins: Advancing periodontitis treatment

A novel approach for fabricating self-healing, intrinsically antibacterial hydrogels for potential periodontitis treatment is presented in this study. Self-healable hydrogels are promising substitutes for brittle hydrogels due to their excellent durability and stability. Drug-loaded regenerative hydrogels have shown good outcomes but face challenges, specifically in managing the development of drug resistance. The hydrogels were prepared by incorporating bioactive oval proteins and hydroxyapatite into polyvinyl alcohol using a simple synthesis method with eco-friendly crosslinkers (oxidized alginate, borax, and divalent metal salts). The synthesized hydrogels exhibited excellent self-healing properties, mechanical robustness, and malleability. Furthermore, characterization techniques confirmed successful crosslinking and interactions within the network. The hydrogels demonstrated significant water absorption, tunable degradation, and potent antibacterial activity against E. coli, S. aureus and P. gingivalis. In vitro studies confirmed good cytocompatibility with epithelial and fibroblasts cells. Wound healing assays further supported the potential of these hydrogels for tissue regeneration applications. This approach offers a promising alternative to traditional drug-loaded hydrogels, overcoming limitations of cost and potential for resistance.

Preparation and characterization of peptide-modified core-shell fibrous substrates with UV-blocking properties for corneal regeneration applications

Effective UV protection is a key aspect of substrates directly exposed to UV radiation. Therefore, in the present study, fibrous substrates of core–shell morphology (PCL-core, PVP-shell) containing peptides based on tryptophan, tyrosine and cysteine (W6, YYC2 and YYC3) were prepared. Spectrophotometric studies showed UV absorption by peptides containing tyrosine and tryptophan in the UVB (up to 80%) and UVA (up to 40%) ranges. Cysteine, in turn, contributed to high antioxidant properties, confirmed by DPPH assay. The presence of peptides contributed to a nonwoven fabric characterized by the ability to absorb UV radiation and prevent the occurrence of oxidative stress (caused by the presence of free radicals). In turn, the increase in the surface zeta potential of the nonwoven after UV irradiation and higher thermal stability (demonstrated by DSC studies) indicated the crosslinking of the PVP layer under UVR, which further contributes to the increased protection of the nonwoven against its effects. In summary, obtained nonwoven exhibited functional similarity to the native cornea, providing a potential solution for enhancing corneal tissue engineering and regenerative medicine applications.

The Effects of Different Developmental Stages on Bone Regeneration of Periodontal Ligament Stem Cells and Periodontal Ligament Cell Sheets In Vitro and Vivo.

Periodontal ligament stem cells (PDLSCs) have broad applications in tissue engineering and regeneration. However, the function of PDLSCs changes in different microenvironments. This study aimed to explore the effects of different developmental stages on the biological characteristics of PDLSCs. Here, PDLSCs were successfully cultured from the periodontal tissues of various groups, including a group with immature roots, a young group with mature roots, and an aging group with mature roots. By comparing the results of the three experimental groups, we found that the donors with immature roots exhibited the best proliferative ability and osteogenic differentiation, while the aging group demonstrated the worst proliferation. The trend for adipogenic differentiation was the opposite to that for osteogenic differentiation. The cell sheet and in vivo experiments revealed that in the immature root group, the cells produced more extracellular matrix (ECM) and new bone and better absorbed the implant materials. These results indicate that PDLSCs perform various functions at different stages of development. In clinical applications of PDLSCs for periodontal regeneration, donors with incompletely developed roots have stronger biological characteristics.