The application of hyaluronic acid in bone regeneration

Potential of hyaluronic acid and collagen-based scaffolds in promoting stem cell neuronal differentiation for neuroregenerative therapies: A review

Stem cell therapy has revolutionized neurodegenerative disease treatment by presenting promising medical applications. Despite their potential, stem cell therapy remains constrained by various limitations, including low differentiation efficiency, difficulties in guiding differentiation, proliferation control, shorter half-life of growth factors, experimental reproducibility, etc. The cellular niche environment is pivotal in effective differentiation of stem cells. Neural regeneration ventures require biomaterial-based 3D scaffolds to simulate in-vivo tissue to solve the niche environment problem. Recent breakthroughs in neural regeneration have led to the development of a biomimetic scaffolds made of Hyaluronic acid (HA) and collagen (COL) that imitate the CNS's extracellular matrix (ECM) for better neural regeneration and repair. HA and COL based scaffold creates a favourable microenvironment for cellular migration, proliferation and survival of the embedded stem cells and promotes neural regeneration. HA regulates cellular activities while COL contributes in healing CNS injuries. Therefore, the utilization of HA-COL based scaffolds is appropriate for regulating cellular responses and behaviour for neural regeneration. This review investigates the synergy between HA and COL in the context of neural-specific applications for repair, regeneration, and recovery as well as augmentation of bioactivity through fabrication techniques such as 3D bioprinting, electrospinning, etc. for neural tissue regeneration.

Review: Advances in multifunctional hydrogels based on carbohydrate polymer and protein in the treatment of diabetic wounds

Diabetic wounds healing is often severely slowed by hyperglycemia, elevated oxidative stress, bacterial infections, and persistent inflammation. This review focuses on the development of hydrogels derived from carbohydrate polymer and protein to facilitate diabetic wound healing. We discuss the primary sources of cellulose, chitosan, hyaluronic acid, sodium alginate, collagen, and gelatin along with their advantages in the preparation of hydrogels. Based on the microenvironment of diabetic wounds, i.e., hyperglycemia, increased oxidative stress, and persistent inflammation, the application of multifunctional hydrogels in promoting diabetic wounds, including stimulus responsiveness, injection self-healing, antibacterial, antioxidant, anti-inflammatory, and synergistic effects, is discussed. We address the main challenges and future perspectives of multifunctional hydrogels based on carbohydrate polymer and protein in the treatment of diabetic wounds.

Osteogenic function of BMP2-modified PEEK scaffolds for orbital fracture repair

This study aimed to investigate the osteogenic function of polyetheretherketone (PEEK) scaffolds modified with bone morphogenetic protein 2 (BMP2) and its possibility for orbital fracture repair. The 3D-printed PEEK sheets were combined with BMP2-loaded hyaluronic acid hydrogel (HAH) to fabricate PEEK-BMP2-HAH composite scaffolds. Bone marrow mesenchymal stem cells (BMSCs) were seeded onto PEEK or PEEK-BMP2-HAH scaffolds. Cell adhesion and cell proliferation were measured by transmission electron microscopy and CCK-8 assay. Alkaline phosphatase (ALP) chromogenic, alizarine red S staining, and PCR analysis of Runt-related transcription factor 2 (Runx2), collagen-I (Col-I), Osterix, and osteopontin (OPN) were performed to assess osteogenic activity. The rat orbital fracture defect model is proposed for evaluating the biocompatibility, osteogenic integration, and functional recovery of PEEK orbital implants. Compared with PEEK, cell adhesion and cell proliferation were increased in PEEK-BMP2-HAH scaffolds. ALP activity and mineralized nodule formation were increased in PEEK-BMP2-HAH scaffolds than that in PEEK the mRNA expression of Runx2, Osterix, Col-I and OPN was increased on PEEK-BMP2-HAH scaffolds than that on PEEK at 14 d of osteogenic induction. Besides, a bone defect animal model revealed that BMP2-HAH-modified PEEK scaffolds could effectively facilitate the repair of the orbital bone defect, with increased expression of OPN and Runx2. BMP2-loaded HAH effectively increased adhesion, proliferation, and osteogenic differentiation of BMSCs on PEEK. PEEK-BMP2-HAH scaffolds are expected to become new materials for orbital fracture repair.

Effect of hyaluronic acid gel with and without metronidazole on healing of extraction sockets in diabetic patients-a randomized controlled study

BACKGROUND

Diabetic patients are associated with a series of post extraction complications, such as delayed healing, greater risk of infections, persistent pain, dry socket and delayed bone formation. There is paucity of studies which indicate the influence of glycemic index and antibiotic prophylaxis in prevention of complications after minor surgical procedures. Various adjuncts such as hydrogels, curcumin and platelet gels are used in the extraction socket to augment healing, minimize complications and promote bone regeneration.

AIM

To assess the effect of hyaluronic acid gel with and without metronidazole on wound healing in post extraction sockets of diabetic patients.

METHODOLOGY

A double blind randomized controlled study was conducted at FDS, RUAS, Bengaluru, India. Diabetic patients indicated for simple extraction of mandibular molars were randomly divided into two groups and prescribed oral metronidazole 1 h prior to extraction. After extraction, 1% hyaluronic acid gel was placed in the sockets of patients in Group A and Group B received 1% hyaluronic acid gel with 5% metronidazole. Soft tissue healing was assessed after one week using wound healing index and photographs of the socket with AutoCAD program. Pain was assessed by VAS. Hard tissue healing was evaluated radiologically using CBCT scans taken immediately after extraction and after one month and analyzed in the 3D slicer software. Pain was assessed by VAS, number of rescue analgesics, complications if any.

RESULTS

There was no statistically significant difference in hard and soft tissue healing and pain scores between the two groups. However, it was statistically significant between the two-time intervals within each group.

CONCLUSION

In patients with short term glycemic control, use of a single dose of oral metronidazole prior to extraction and placement of 1% hyaluronic acid gel in the extraction socket resulted in uneventful healing with evidence of bone formation at one month. Addition of 5% metronidazole to the gel seems to have no added advantage.

CLINICAL TRIAL NUMBER

Not registered.

Revolutionizing bone healing: the role of 3D models

The increasing incidence of bone diseases has driven research towards Bone Tissue Engineering (BTE), an innovative discipline that uses biomaterials to develop three-dimensional (3D) scaffolds capable of mimicking the natural environment of bone tissue. Traditional approaches relying on two-dimensional (2D) models have exhibited significant limitations in simulating cellular interactions and the complexity of the bone microenvironment. In response to these challenges, 3D models such as organoids and cellular spheroids have emerged as effective tools for studying bone regeneration. Adult mesenchymal stem cells have proven crucial in this context, as they can differentiate into osteoblasts and contribute to bone tissue repair. Furthermore, the integration of composite biomaterials has shown substantial potential in enhancing bone healing. Advanced technologies like microfluidics offer additional opportunities to create controlled environments for cell culture, facilitating more detailed studies on bone regeneration. These advancements represent a fundamental step forward in the treatment of bone pathologies and the promotion of skeletal health. In this review, we report on the evolution of in vitro culture models applied to the study of bone healing/regrowth, starting from 2 to 3D cultures and microfluids. The different methodologies of in vitro model generation, cells and biomaterials are presented and discussed.

Functional polysaccharide-based hydrogel in bone regeneration: From fundamentals to advanced applications

Bone regeneration is limited and generally requires external intervention to promote effective repair. Autografts, allografts, and xenografts as traditional methods for addressing bone defects have been widely utilized, their clinical applicability is limited due to their respective disadvantages. Fortunately, functional polysaccharide hydrogels have gained significant attention in bone regeneration due to their exceptional drug-loading capacity, biocompatibility, and ease of chemical modification. They also provide an optimal microenvironment for bone repair and regeneration. This review provides an overview of various functional polysaccharide hydrogels derived from biocompatible materials, focusing on their applications in intelligent delivery systems, bone tissue regeneration, and cartilage defect repair. Particularly, the incorporation of bioactive molecules into the design of functional polysaccharide hydrogels has been shown to significantly enhance bone regeneration. Additionally, this review emphasizes the preparation methods for functional polysaccharide hydrogels and associated the bone healing mechanisms. Finally, the limitations and future prospects of functional polysaccharide hydrogels are thoroughly evaluated.

Injectable visible light cross-linking aldehyde-based methacrylated hyaluronic acid hydrogels enhance cartilage repair via improved BMSC homing and chondrogenic differentiation

Self-repair of articular cartilage defects is a significant challenge that can be addressed using drug-infused hydrogels, which improve injection convenience and provide immediate in situ adhesion. In this study, we developed a hydrogel incorporating Lipo@Kartogenin (KGN) and the cationic functional peptide SKPPGTSS (SKP) linked to aldehyde-based methacrylated hyaluronic acid (AHAMA). The innovative injectable hydrogel responded to visible light, allowing cross-linking under white light (∼30 s) and effective adhesion to cartilage tissue. The hydrogel facilitated the sustained release of KGN and SKP over approximately 28 days as it degraded, thereby promoting the homing and differentiation of endogenous bone marrow-derived mesenchymal stem cells (BMSCs). Transcriptome sequencing showed that Smad4 expression and activation of the TGF-β signaling pathway are fundamental to these processes. In vivo studies in Sprague-Dawley (SD) rats showed that this hydrogel supports optimal hyaline cartilage regeneration within 8 weeks. In conclusion, our visible light-responsive adhesive co-delivery hydrogel effectively recruited native BMSCs to cartilage lesion sites and provided an environment conducive to their differentiation into cartilage, thereby facilitating effective cartilage regeneration. This innovation represents a novel approach to the clinical repair of cartilage defects.

Youthful Stem Cell Microenvironments: Rejuvenating Aged Bone Repair Through Mitochondrial Homeostasis Remodeling

Extracellular matrix (ECM) derived from mesenchymal stem cells regulates antioxidant properties and bone metabolism by providing a favorable extracellular microenvironment. However, its functional role and molecular mechanism in mitochondrial function regulation and aged bone regeneration remain insufficiently elucidated. This proteomic analysis has revealed a greater abundance of proteins supporting mitochondrial function in the young ECM (Y-ECM) secreted by young bone marrow-derived mesenchymal stem cells (BMMSCs) compared to the aged ECM (A-ECM). Further studies demonstrate that Y-ECM significantly rejuvenates mitochondrial energy metabolism in adult BMMSCs (A-BMMSCs) through the promotion of mitochondrial respiratory functions and amelioration of oxidative stress. A-BMMSCs cultured on Y-ECM exhibited enhanced multi-lineage differentiation potentials in vitro and ectopic bone formation in vivo. Mechanistically, silencing of silent information regulator type 3 (SIRT3) gene abolished the protective impact of Y-ECM on A-BMMSCs. Notably, a novel composite biomaterial combining hyaluronic acid methacrylate hydrogel microspheres with Y-ECM is developed, which yielded substantial improvements in the healing of bone defects in an aged rat model. Collectively, these findings underscore the pivotal role of Y-ECM in maintaining mitochondrial redox homeostasis and present a promising therapeutic strategy for the repair of aged bone defects.

Gallol-containing chitosan/hyaluronic acid composite hydrogel patches as wound sealing and dressing materials

Recently, various adhesive materials have been developed for versatile biomedical applications owing to their rapid and strong adhesion to tissues in water-rich environments. One such example is gallol-containing chitosan (CHI-G), which contains multiple gallol and amine groups in its backbone. However, the practical application of CHI-G alone is limited owing to its intrinsic mechanical strength and undesirable immune responses. In this study, we developed Ca2+ ions- and hyaluronic acid-containing CHI-G (CHC) patches to prevent anastomotic leakage and accelerate wound healing. CHC hydrogel patches showed increased elastic modulus values (809.4 ± 181.7 Pa) compared to that of CHI-G hydrogel patches (137.0 ± 16.3 Pa). In addition, the bursting pressure (78.2 ± 3.5 mmHg) of CHC hydrogel patch-applied porcine intestine was far higher than those of the control (4.13 ± 0.4 mmHg) and HA groups (14.5 ± 2.5 mmHg). CHC hydrogel patches showed suitable mechanical properties and biocompatibility for wound-sealing and dressing applications in water-rich environments. Notably, the CHC hydrogel patch-applied wound healing animal model exhibited a healing rate of over 90 % at 14 days post-surgery, notably higher than that of the control group (76 %). These findings suggest that CHC patches have considerable potential as effective wound dressings and sealing materials.

Intra-Articular Hyaluronic Acid for Knee Osteoarthritis: A Systematic Umbrella Review

Objective: to evaluate the efficacy, safety, and cost-effectiveness of intra-articular hyaluronic acid (IAHA) in treating osteoarthritis (OA), considering innovations in formulations, comparative outcomes, and variability in guidelines. This review aims to synthesize evidence supporting the role of IAHA in multimodal treatment strategies. Materials and Methods: A general, narrative, umbrella review of systematic reviews and meta-analyses was conducted. Clinical practice recommendations and guidelines for IAHA use were also reviewed and evaluated. A comprehensive search was conducted across the main medical data sources. Inclusion criteria focused on studies evaluating the efficacy, safety, and impact of IAHA. Key outcomes included pain reduction (e.g., WOMAC, VAS), functional improvement, safety, and cost-effectiveness. Results: IAHA showed moderate efficacy in pain relief and functional improvement, especially in early-to-moderate OA. The results indicate that hybrid formulations and combination therapies show better clinical outcomes, with expanded efficacy and potential chondroprotection. However, heterogeneity between studies was noted, reflecting variability in patient populations and intervention protocols. International guidelines varied significantly, with some opposing routine use (e.g., AAOS, NICE) and others endorsing IAHA more or less conditionally (e.g., ESCEO, OARSI). Conclusions: IAHA remains a treatment modality in the arsenal of selected populations of people with OA, especially for early and moderate disease. High-quality, standardized studies are still needed to refine IAHA's role and establish personalized guidelines for individual patients. A concerted effort to harmonize global recommendations and economic strategies, such as tiered pricing, can increase equitable access and optimize IAHA's integration of multimodal treatment for OA.

A Chinese drug-compatibility-based approach to purslane hydrogels for acute eczema therapy

Purslane (Portulaca oleracea L.) with heat-clearing and detoxicating, anti-inflammatory and resolving swelling, relieving itching and astringing function, has remarkable efficacy for acute eczema. However, most of the clinical applications of purslane are freshly prepared decoction, not as easy to apply as cream, because the decoction is easy to breed bacteria and easy to oxidize. Here, based on the theory of Chinese medicines compatibility, we made a purslane-tannic acid hydrogel (PL-HATA) by simple methods under mild conditions to solve the drawbacks of easy oxidation and inconvenience of use of Purslane. The antimicrobial activity of PL-HATA hydrogel can exert an excellent antimicrobial effect, reducing the flora on the skin of acute eczema and further relieving the symptoms of acute eczema. At the same time, it creates a normal reactive oxygen species (ROS) microenvironment for acute eczema and promotes recovery from acute eczema. It also improves the symptoms of acute eczema by promoting cell proliferation and migration. Importantly, it resulted in improved skin lesion scores, scratching behavior, eosinophil infiltration, swelling and inflammation levels, immune homeostasis, and histopathological changes in rats with acute eczema. Besides, HATA hydrogel is not only suitable for Purslane's decocted metabolites but also for Purslane's freshly squeezed metabolites. This purslane application protocol solved the drawbacks of Purslane's decoction, improved its storage stability and convenience of use, which is the key issue to further promote its clinical application.

Remodeling the Proinflammatory Microenvironment in Osteoarthritis through Interleukin-1 Beta Tailored Exosome Cargo for Inflammatory Regulation and Cartilage Regeneration

Osteoarthritis (OA) presents a significant therapeutic challenge, with few options for preserving joint cartilage and repairing associated tissue damage. Inflammation is a pivotal factor in OA-induced cartilage deterioration and synovial inflammation. Recently, exosomes derived from human umbilical cord mesenchymal stem cells (HucMSCs) have gained recognition as a promising noncellular therapeutic modality, but their use is hindered by the challenge of harvesting a sufficient number of exosomes with effective therapeutic efficacy. Given that HucMSCs are highly sensitive to microenvironmental signals, we hypothesized that priming HucMSCs within a proinflammatory environment would increase the number of exosomes secreted with enhanced anti-inflammatory properties. Subsequent miRNA profiling and pathway analysis confirmed that interleukin-1 beta (IL-1β)-induced exosomes (C-Exos) exert positive effects through miRNA regulation and signaling pathway modulation. In vitro experiments revealed that C-Exos enhance chondrocyte functionality and cartilage matrix production, as well as macrophage polarization, thereby enhancing cartilage repair. C-Exos were encapsulated in hyaluronic acid hydrogel microspheres (HMs) to ensure sustained release, leading to substantial improvements in the inflammatory microenvironment and cartilage regeneration in a rat OA model. This study outlines a strategy to tailor exosome cargo for anti-inflammatory and cartilage regenerative purposes, with the functionalized HMs demonstrating potential for OA treatment.

Synthesis of PVA-Based Hydrogels for Biomedical Applications: Recent Trends and Advances

There is ongoing research for biomedical applications of polyvinyl alcohol (PVA)-based hydrogels; however, the execution of this has not yet been achieved at an appropriate level for commercialization. Advanced perception is necessary for the design and synthesis of suitable materials, such as PVA-based hydrogel for biomedical applications. Among polymers, PVA-based hydrogel has drawn great interest in biomedical applications owing to their attractive potential with characteristics such as good biocompatibility, great mechanical strength, and apposite water content. By designing the suitable synthesis approach and investigating the hydrogel structure, PVA-based hydrogels can attain superb cytocompatibility, flexibility, and antimicrobial activities, signifying that it is a good candidate for tissue engineering and regenerative medicine, drug delivery, wound dressing, contact lenses, and other fields. In this review, we highlight the current progresses on the synthesis of PVA-based hydrogels for biomedical applications explaining their diverse usage across a variety of areas. We explain numerous synthesis techniques and related phenomena for biomedical applications based on these materials. This review may stipulate a wide reference for future acumens of PVA-based hydrogel materials for their extensive applications in biomedical fields.

Integrating Micro- and Nanostructured Platforms and Biological Drugs to Enhance Biomaterial-Based Bone Regeneration Strategies

Bone defects resulting from congenital anomalies and trauma pose significant clinical challenges for orthopedics surgeries, where bone tissue engineering (BTE) aims to address these challenges by repairing defects that fail to heal spontaneously. Despite numerous advances, BTE still faces several challenges, i.e., difficulties in detecting and tracking implanted cells, high costs, and regulatory approval hurdles. Biomaterials promise to revolutionize bone grafting procedures, heralding a new era of regenerative medicine and advancing patient outcomes worldwide. Specifically, novel bioactive biomaterials have been developed that promote cell adhesion, proliferation, and differentiation and have osteoconductive and osteoinductive characteristics, stimulating tissue regeneration and repair, particularly in complex skeletal defects caused by trauma, degeneration, and neoplasia. A wide array of biological therapeutics for bone regeneration have emerged, drawing from the diverse spectrum of gene therapy, immune cell interactions, and RNA molecules. This review will provide insights into the current state and potential of future strategies for bone regeneration.

Advancements in Hyaluronic Acid Effect in Alveolar Ridge Preservation: A Narrative Review

Background/Objectives: Tooth extraction induces significant alveolar ridge dimensional changes and soft tissue modifications, often leading to challenges in implant placement or conventional prosthetic rehabilitation. Alveolar Ridge Preservation (ARP) strategies aim to mitigate post-extraction resorption of the alveolar ridge, enhancing both the quality and quantity of bone and soft tissue during healing. Hyaluronic acid (HYA) has emerged as a promising biological agent for ARP due to its osteoinductive, antimicrobial, and anti-inflammatory properties. However, the effects of HYA in ARP remain inconsistently reported. This study aims to assess current clinical and preclinical evidence regarding the biological effects of HYA and its application in ARP. Additionally, it evaluates HYA's impact-alone or in combination with other products-on hard and soft tissue dimensional changes, early wound healing, and implant success rates. Methods: A comprehensive electronic literature search was conducted, and studies meeting the inclusion criteria were critically evaluated. Relevant data were extracted from the final selection of articles. Results: Thirteen publications were evaluated. Some studies reported a significantly improved newly formed bone following ARP with intra-socket HYA application as a single approach (p = 0.004). Combining HYA with a bone graft and a free palatal graft resulted in significantly greater amounts of newly formed and mature bone, reduced clinical bone width changes, lower radiographic crestal bone loss (p < 0.01), and diminished radiological volumetric and linear bone resorption (p = 0.018). Short-term follow-up data indicated improved soft tissue healing associated with HYA-based ARP. While HYA appears to have a protective effect on ridge dimensional changes in ARP, other studies reported no significant differences in radiographic bone dimensional changes or soft tissue improvement. Conclusions: The addition of HYA to bone grafts may enhance some ARP outcomes. However, the variability in outcomes and methodologies across the evaluated studies precludes drawing definitive clinical conclusions. Further robust research is needed to clarify HYA's role in ARP. With respect to clinical significance enhancing the understanding of ARP management strategies and their effects on post-extraction sockets empowers clinicians to make more informed decisions. The knowledge of HYA effects facilitates the selection of personalized ARP approaches tailored to optimize outcomes for subsequent interventions.

Hyaluronic Acid-Based Drug Delivery Systems for Cancer Therapy

In recent years, hyaluronic acid (HA) has attracted increasing attention as a promising biomaterial for the development of drug delivery systems. Due to its unique properties, such as high biocompatibility, low toxicity, and modifiability, HA is becoming a basis for the creation of targeted drug delivery systems, especially in the field of oncology. Receptors for HA overexpressed in subpopulations of cancer cells, and one of them, CD44, is recognized as a molecular marker for cancer stem cells. This review examines the role of HA and its receptors in health and tumors and analyzes existing HA-based delivery systems and their use in various types of cancer. The development of new HA-based drug delivery systems will bring new opportunities and challenges to anti-cancer therapy.

Cultured Chinese Giant Salamander Skin and Skin Secretions as a Source of Bioactive Peptides for Food and Medicine

Amphibians are enjoyable globally for their culinary value and are increasingly considered alternative protein sources. However, the skin of edible amphibians, especially giant salamanders, is often discarded without much thought. However, this underutilized resource holds significant potential for yielding valuable proteins and bioactive peptides (BPs). These peptides, such as brevinins, bombesins, dermaseptins, esculentins, magainins, temporins, tigerinins, and salamandrins, possess a wide range of biological activities, including antioxidant, antimicrobial, anticancer, and antidiabetic properties. This review provides a comprehensive analysis of the various BPs derived from giant salamander skin or secretions and their associated biological functions. Furthermore, it examines the nutritional composition of giant salamanders, their production status, and the challenges surrounding the use of their skin and secretions. This review also explores the potential applications of these BPs in the food and biomedical industries, particularly as multifunctional food additives, dietary supplements, and drug delivery agents.

Design of patient-specific mandibular reconstruction plates and a hybrid scaffold

BACKGROUND

Managing segmental mandibular defects remains challenging, requiring a multidisciplinary approach despite the remarkable progress in mandibular reconstruction plates, finite element methods, computer-aided design and manufacturing techniques, and novel surgical procedures. Complex surgeries require a comprehensive approach, as using only reconstruction plates or tissue scaffolds may not be adequate for optimal results. The limitations of the treatment options should be investigated towards a patient-specific trend to provide shorter surgery time, better healing, and lower costs. Integrated hybrid scaffold systems are promising in improving mechanical properties and facilitating healing. By combining different materials and structures, hybrid scaffolds can provide enhanced support and stability to the tissue regeneration process, leading to better patient outcomes. The use of such systems represents a significant advancement in tissue engineering and a wide range of medical procedures.

MATERIALS AND METHODS

A head and neck computed tomography (CT) data of a patient with odontogenic myxoma was used for creating a three-dimensional (3D) mandible model. Virtual osteotomies were performed to create a segmental defect model, including the angulus mandibulae region. The first mandibular reconstruction plate was designed. Finite elemental analyses (FEA) and topology optimizations were performed to create two different reconstruction plates for different treatment scenarios. The FEA were performed for the resulting two plates to assess their biomechanical performance. To provide osteoconductive and osteoinductive properties a scaffold was designed using the defect area. A biomimetic Tricalcium phosphate-Polycaprolactone (TCP-PCL) hybrid bone scaffold enhanced with Hyaluronic acid dipping was manufactured.

RESULTS

The results of the in-silico analysis indicate that the designed reconstruction plates possess robust biomechanical performance and demonstrate remarkable stability under the most rigorous masticatory activities. Using the Voronoi pattern decreased the mass by %37 without losing endurance. Using reconstruction plates and hybrid scaffolds exhibits promising potential for clinical applications, subject to further in vivo and clinical studies.

Photoelectrocatalytic degradation of hyaluronic acid and regulation effects of its degradation products on gut microbiota in vitro

Hyaluronic acid (HA) has multiple biological activities which are closely related to its molecular weight. In the present study, the photoelectrocatalytic method was established for HA degradation and the influences of bias potentials, H2O2 additions and reaction times on the degradation results were investigated to optimize the reaction condition. Moreover, a series of analysis methods, such as FT-IR and NMR were used to analyze chemical compositions of the degradation products, revealing that photoelectrocatalytic degradation did not damage the structural blocks of HA obviously. Then 11 oligosaccharides with polymerization degrees from 2 to 8 in the degradation products were identified by mass spectroscopy and their reducing ends were all GlcA or AraA. In addition, in the photoelectrocatalytic degradation of HA, ·OH were identified as the most influential among the produced free radicals, and it could be proposed that ·OH specifically targeted the anomeric carbon of GlcA, resulting in the disaggregation of polysaccharides chain. Furthermore, the results of in vitro fermentation with fecal microbiota demonstrated that HA and its degradation products regulated microbiota structure discriminately, indicating their possible different outcomes as nutritional supplements and agents.

A sugary solution: Harnessing polysaccharide-based materials for osteoporosis treatment

Osteoporosis, a prevalent skeletal disorder characterized by diminished bone density, compromised microstructure, and heightened fracture susceptibility, poses a growing public health concern exacerbated by aging demographics. Polysaccharides-based materials, derived from a diverse range of sources, exhibit exceptional biocompatibility. They possess a structure similar to the extracellular matrix, which can enhance cell adhesion in vivo, and demonstrate superior biological activity compared to artificial materials. This study delved into an in-depth examination of the various biomaterials and polysaccharide families associated with the treatment of osteoporosis. This article elucidates the benefits and attributes of polysaccharide-based materials in contrast to current clinical treatment modalities, delineating how these materials address prevalent challenges in the clinical management of osteoporosis. An overview of the prospective applications of polysaccharide-based materials in the future is also provided, as well as outlines the challenges that should be addressed prior to the clinical implementation of such materials.

Advances and Challenges in Polymer-Based Scaffolds for Bone Tissue Engineering: A Path Towards Personalized Regenerative Medicine

Polymers have become essential in advancing bone tissue engineering, providing adaptable bone healing and regeneration solutions. Their biocompatibility and biodegradability make them ideal candidates for creating scaffolds that mimic the body's natural extracellular matrix (ECM). However, significant challenges remain, including degradation by-products, insufficient mechanical strength, and suboptimal cellular interactions. This article addresses these challenges by evaluating the performance of polymers like poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and polylactic acid (PLA) in scaffold development. It also explores recent innovations, such as intelligent polymers, bioprinting, and the integration of bioactive molecules to enhance scaffold efficacy. We propose that overcoming current limitations requires a combination of novel biomaterials, advanced fabrication techniques, and tailored regulatory strategies. The future potential of polymer-based scaffolds in personalised regenerative medicine is discussed, focusing on their clinical applicability.

Brain-derived neurotrophic factor promotes bone regeneration in a canine model of peri-implantitis

PURPOSE

The present study aims to determine whether the brain-derived neurotrophic factor (BDNF)/high-molecular-weight hyaluronic acid (HMW-HA) complex could regenerate bone around implants lost due to peri-implantitis.

METHODS

Dogs had their three premolars extracted, and three implants were placed on each side. After osseointegration, 3-0 silk threads were ligated around the healing abutment for 12 weeks. Implants were classified into four groups-no treatment (control group), non-surgical debridement (debridement group), non-surgical debridement with application of HMW-HA (HMW-HA group), and non-surgical debridement with application of BDNF/HMW-HA complex (BDNF/HMW-HA group). Probing pocket depth (PPD), attachment level (AL), and bleeding on probing (BOP) were recorded before and 12 weeks after each treatment. Standardized intraoral radiographs were obtained, and histological analysis was conducted.

RESULTS

The bone level on radiographs significantly improved (median -0.15 mm, IQR -0.31 to 0.10) only in the BDNF/HMW-HA group, while changes in PPD and AL were similar to those in other groups. The BOP positivity rate decreased in the debridement and BDNF/HMW-HA groups. Unlike images of the other groups, histological images of the BDNF/HMW-HA group showed no epithelial migration toward the tip of the implant. Inflammatory cell infiltration was reduced compared with that in the other groups. New bone was observed around the implants only in the BDNF/HMW-HA group.

CONCLUSIONS

The BDNF/HMW-HA complex appears to promote bone regeneration when combined with non-surgical debridement for peri-implantitis.

Early exercise disrupts a pro-repair extracellular matrix program during zebrafish fin regeneration

Understanding how mechanical stimulation from exercise influences cellular responses during tissue repair could enhance therapeutic strategies. We explored zebrafish caudal fin regeneration to study exercise impacts on a robust model of tissue regeneration. We used a swim tunnel to determine that exercise initiated during but not after blastema establishment impaired fin regeneration, including of the bony ray skeleton. Long-term tracking of fluorescently labeled cell lineages showed exercise disrupted blastemal mesenchyme formation. Transcriptomic profiling and section staining indicated exercise reduced an extracellular matrix (ECM) gene expression program, including for hyaluronic acid (HA) synthesis. Like exercise, HA synthesis inhibition or blastemal HA depletion disrupted blastema formation. We considered if injury-upregulated HA establishes a pro-regenerative environment facilitating mechanotransduction. HA density across the blastema correlated with nuclear localization of the mechanotransducer Yes-associated protein (Yap). Further, exercise loading or reducing HA decreased nuclear Yap and cell proliferation. We conclude early exercise during fin regeneration disrupts expression of an HA-rich ECM supporting blastema expansion. These results highlight the interface between mechanotransduction and ECM as consideration for timing exercise interventions and developing regenerative therapies.

Significance Statement

Controlled exercise promotes healing and recovery from severe skeletal injuries. However, properly timed interventions are essential to promote recovery and prevent further damage. We use zebrafish caudal fin regeneration to mechanistically study exercise impacts on a naturally robust and experimentally accessible model of tissue repair. We link detrimental early exercise effects during fin regeneration to impaired ECM synthesis, mechanotransduction, and cell proliferation. These insights could explain the value of delaying the onset of physical therapy and suggest pursuing therapies that maintain ECM integrity for regenerative rehabilitation.

Nano-scaffold-based delivery systems of antimicrobial agents in the treatment of osteomyelitis ; a narrative review

Osteomyelitis caused by drug-resistant pathogens is one of the most important medical challenges due to high rates of mortality and morbidity, and limited therapeutical options. The application of novel nano-scaffolds loaded with antibiotics has widely been studied and extensively evaluated for in vitro and in vivo inhibition of pathogens, regenerating damaged bone tissue, and increasing bone cell proliferation. The treatment of bone infections using the local osteogenic scaffolds loaded with antimicrobial agents may efficiently overcome the problems of the systemic use of antimicrobial agents and provide a controlled release and sufficient local levels of antibiotics in the infected sites. The present study reviewed various nano-scaffolds delivery systems of antimicrobial drugs evaluated to treat osteomyelitis. Nano-scaffolds offer promising approaches because they simulate natural tissue regeneration in terms of their mechanical, structural, and sometimes chemical properties. The potential of several nano-scaffolds prepared by natural polymers such as silk, collagen, gelatin, fibrinogen, chitosan, cellulose, hyaluronic, alginate, and synthetic compounds such as polylactic acid, polyglycolic acid, poly (lactic acid-co-glycolic acid), poly-ɛ-caprolactone have been studied for usage as drug delivery systems of antimicrobial agents to treat osteomyelitis. In addition to incorporated antimicrobial agents and the content of scaffolds, the physical and chemical characteristics of the prepared delivery systems are a determining factor in their effectiveness in treating osteomyelitis.

Advances in Bioceramics for Bone Regeneration: A Narrative Review

Large osseous defects resulting from trauma, tumor resection, or fracture render the inherent ability of the body to repair inadequate and necessitate the use of bone grafts to facilitate the recovery of both form and function of the bony defect sites. In the United States alone, a large number of bone graft procedures are performed yearly, making it an essential area of investigation and research. Synthetic grafts represent a potential alterative to autografts due to their patient-specific customizability, but currently lack widespread acceptance in the clinical space. Early in their development, non-autologous bone grafts composed of metals such as stainless steel and titanium alloys were favorable due to their biocompatibility, resistance to corrosion, mechanical strength, and durability. However, since their inception, bioceramics have also evolved as viable alternatives. This review aims to present an overview of the fundamental prerequisites for tissue engineering devices using bioceramics as well as to provide a comprehensive account of their historical usage and significant advancements over time. This review includes a summary of commonly used manufacturing techniques and an evaluation of their use as drug carriers and bioactive coatings-for therapeutic ion/drug release, and potential avenues to further enhance hard tissue regeneration.

RNA Coating Promotes Peri-Implant Osseointegration

In addition to transmitting and carrying genetic information, RNA plays an important abiotic role in the world of nanomaterials. RNA is a natural polyanionic biomacromolecule, and its ability to promote osteogenesis by binding with other inorganic materials as an osteogenic induction agent was discovered only recently. However, whether it can promote osseointegration on implants has not been reported. Here, we investigated the effect of the RNA-containing coating materials on peri-implant osseointegration. Total RNA extracted from rat muscle tissue was used as an osteogenic induction agent, and hyaluronic acid (HA) was used to maintain its negative charge. In simulated body fluids (SBF), in vitro studies demonstrated that the resulting material encouraged calcium salt deposition. Cytological experiments showed that the RNA-containing coating induced greater cell adhesion and osteogenic differentiation in comparison to the control. The results of animal experiments showed that the RNA-containing coating had osteoinductive and bone conduction activities, which are beneficial for bone formation and osseointegration. Therefore, the RNA-containing coatings are useful for the surface modification of titanium implants to promote osseointegration.

Bioinspired injectable hydrogels for bone regeneration

The effective regeneration of bone/cartilage defects remains a significant clinical challenge, causing irreversible damage to millions annually.Conventional therapies such as autologous or artificial bone grafting often yield unsatisfactory outcomes, emphasizing the urgent need for innovative treatment methods. Biomaterial-based strategies, including hydrogels and active scaffolds, have shown potential in promoting bone/cartilage regeneration. Among them, injectable hydrogels have garnered substantial attention in recent years on account of their minimal invasiveness, shape adaptation, and controlled spatiotemporal release. This review systematically discusses the synthesis of injectable hydrogels, bioinspired approaches-covering microenvironment, structural, compositional, and bioactive component-inspired strategies-and their applications in various bone/cartilage disease models, highlighting bone/cartilage regeneration from an innovative perspective of bioinspired design. Taken together, bioinspired injectable hydrogels offer promising and feasible solutions for promoting bone/cartilage regeneration, ultimately laying the foundations for clinical applications. Furthermore, insights into further prospective directions for AI in injectable hydrogels screening and organoid construction are provided.

Bioactive modification of cyclic olefin copolymer (COC) film surfaces by hyaluronic acid and chitosan for enhanced cell adhesion

Cyclic olefin copolymer (COC) has recently emerged as an attractive material in biomedical fields for its high purity, excellent stability and chemical resistance, particularly in applications of microfluidic chips, prefilled syringes and bone regeneration. However, the high hydrophobicity of COC has inhibited the adhesion of cells and biological macromolecules, such as proteins, etc., significantly limiting its broader applications. In this study, we propose a new method to modify COC surfaces by sequential coating with polydopamine (PDA) followed by hyaluronic acid (HA) or O-carboxymethyl chitosan (CMC), while comparing the impacts of the positively charged HA and negatively charged CMC on protein adsorption and cell adhesion. FTIR and XPS measurements confirmed the successful modification on COC films, resulting in surfaces with highly increased hydrophilicity, anti-oxidative properties, and improved protein adsorption. Moreover, negatively charged HA, with signal transduction capabilities showed a greater effect in promoting cell adhesion. Thus, we present a straightforward strategy for enhancing the hydrophilicity of COC surfaces, offering new insights into COC modification and potential biomedical applications.

Green Synthesis of Silver Nanoparticles with Roasted Green Tea: Applications in Alginate-Gelatin Hydrogels for Bone Regeneration

The incorporation of silver nanoparticles (AgNPs) into alginate-gelatin (Alg-Gel) hydrogels can enhance the properties of these materials for bone regeneration applications, due to the antimicrobial properties of AgNPs and non-cytotoxic concentrations, osteoinductive properties, and regulation of stem cell proliferation and differentiation. Here, the hydrogel formulation included 2% (w/v) sodium alginate, 4 µg/mL AgNPs, and 2.5% (w/v) gelatin. AgNPs were synthesized using a 2% (w/v) aqueous extract of roasted green tea with silver nitrate. The aqueous extract of roasted green tea for AgNP synthesis was characterized using HPLC and UHPLC-ESI-QTOF-MS/MS, and antioxidant capacity was measured in Trolox equivalents (TE) from 4 to 20 nmol/well concentrations. Stem cells from human exfoliated deciduous tooth cells were used for differentiation assays including positive (SHEDs/hydrogel with AgNPs) and negative controls (hydrogel without AgNPs). FTIR was used for hydrogel chemical characterization. Statistical analysis (p < 0.05, ANOVA) confirmed significant findings. Roasted green tea extract contained caffeine (most abundant), (-)-Gallocatechin, gallic acid, and various catechins. XRD analysis revealed FCC structure, TEM showed quasispheroidal AgNPs (19.85 ± 3 nm), and UV-Vis indicated a plasmon surface of 418 nm. This integration of nanotechnology and biomaterials shows promise for addressing bone tissue loss in clinical and surgical settings.

Soluble hyaluronic acid microneedle arrays mediated RGD-modified liposome delivery for pain relief during photodynamic therapy by blocking TRPV1

In photodynamic therapy (PDT), reactive oxygen species (ROS) are key products that induce cell death, and increasing amount of ROS is a crucial way to enhance PDT efficacy. However, the generated ROS stimulates the transient receptor potential vanilloid 1 channel (TRPV1), which can be activated in the pain pathway and then exacerbate pain. Herein, we utilized arginine-glycine-aspartate (RGD) peptide-modified liposomes for encapsulation Chlorin e6 (Ce6) and capsazepine (Cz), a receptor antagonist of TRPV1, to prepare drug-loaded liposomes, RLCC. Soluble hyaluronic acid microneedle arrays (MNs), which possess sufficient skin penetration capability and excellent biosafety, was applied for in situ delivery of RLCC. With the aid of RGD peptides, the efficiency of intracellular liposomal uptake and the dispersion of drugs in tumor after delivery by MNs were significantly enhanced, showcasing tremendous potential for improving the PDT efficacy. Besides, through the analysis of sciatic nerve signals in mice during PDT, RLCC demonstrated remarkable effectiveness in alleviating pain by significantly reducing nerve impulses. Hence, RLCC demonstrated outstanding effectiveness in PDT and effectively alleviated the associated pain. Overall, this research highlights the potential of utilizing MNs for the in situ delivery of RLCC, facilitating effective PDT while addressing the issue of pain during the treatment.

Wharton's jelly of the umbilical cord serves as a natural biomaterial to promote osteogenesis

Various factors can contribute to bone damage or loss, presenting challenges for bone regeneration. Our study explores the potential clinical applications of two processed forms of Wharton's jelly of the human umbilical cord for treating bone loss. Wharton's jelly from fresh umbilical cords underwent two distinct processes: (1) frozen Wharton's jelly (WJF), preserved with cryoprotective agents, and (2) decellularized Wharton's jelly matrix (WJD), prepared only via lyophilization without cryoprotectants. Both WJD and WJF are rich in collagen, hyaluronan, and polysaccharide proteins. Notably, WJD exhibited a porous structure lacking nuclei from human umbilical cord mesenchymal stem cells, unlike WJF. In direct contact experiments, WJD stimulated osteoblast migration, enhanced osteoblast maturation, and promoted calcium deposition for bone formation when administered to cultured rat osteoblasts. Furthermore, in transwell co-culture experiments, both WJD and WJF increased the rat osteoblast expression of RUNX2 and OPN genes, elevated alkaline phosphatase levels, and enhanced extracellular calcium precipitation, indicating their role in osteoblast maturation and new bone formation. Hyaluronic acid, one of the ingredients from WJD and WJF, was identified as a key component triggering osteogenesis. In vivo experiments involved creating circular bone defects in the calvarias of rats, where WJD and WJF were separately implanted and monitored over five months using micro-computerized tomography. Our results demonstrated that both WJD and WJF enhanced angiogenesis, collagen formation, osteoblast maturation, and bone growth within the bone defects. In summary, WJD and WJF, natural biomaterials with biocompatibility and nontoxicity, act not only as effective scaffolds but also promote osteoblast adhesion and differentiation, and accelerate osteogenesis.

Enhanced alveolar ridge preservation with hyaluronic acid-enriched allografts: a comparative study of granular allografts with and without hyaluronic acid addition

PURPOSE

Ridge preservation is essential to restore alveolar ridge volume and to enhance esthetic and functional outcomes for dental implants. The addition of hyaluronic acid to allogeneic bone substitute materials might enhance these outcomes. This clinical study evaluated the efficacy of ridge preservation after tooth extraction using granular allografts with and without hyaluronic acid addition.

METHODS

In this retrospective study, 40 patients with compromised extraction sockets were enrolled. Among them, 19 received particulate allogeneic bone substitutes (Allo), 21 received allogeneic bone substitutes with hyaluronic acid (AlloHya). Vertical and horizontal graft stability, graft shrinkage rate, and bone mineral density were assessed using radiographic measurements on CBCT scans conducted before tooth extraction, directly after ridge preservation and after four months. Patients were followed up 12 months post-implantation.

RESULTS

Vertical height loss after 4 months was significantly greater in the Allo group (-0.82 ± 0.95 mm) compared to the AlloHya group (-0.19 ± 0.51 mm; p = 0.011). Graft shrinkage rate was 16.9 ± 11.5% (Allo) and 10.3 ± 7.7% (AlloHya) (p = 0.038). After four months, average bone density was significantly higher in the AlloHya compared to the Allo group (p = 0.004). Nearly all implants (39 out of 40) were classified as "Success" according to the ICOI scheme, with no differences in implant quality between the two study groups.

CONCLUSIONS

Improved graft stability, reduced resorption, and increased bone density were observed in hyaluronic acid-enriched allografts compared to pure allografts. Adding hyaluronic acid to allogeneic bone grafts significantly enhanced outcomes in ridge preservation.

PTX3 promotes cementum formation and cementoblast differentiation via HA/ITGB1/FAK/YAP1 signaling pathway

Cementum is a vital component of periodontium, yet its regeneration remains a challenge. Pentraxin 3 (PTX3) is a multifunctional glycoprotein involved in extracellular matrix remodeling and bone metabolism regulation. However, the role of PTX3 in cementum formation and cementoblast differentiation has not been elucidated. In this study, we initially observed an increase in PTX3 expression during cementum formation and cementoblast differentiation. Then, overexpression of PTX3 significantly enhanced the differentiation ability of cementoblasts. While conversely, PTX3 knockdown exerted an inhibitory effect. Moreover, in Ptx3-deficient mice, we found that cementum formation was hampered. Furthermore, we confirmed the presence of PTX3 within the hyaluronan (HA) matrix, thereby activating the ITGB1/FAK/YAP1 signaling pathway. Notably, inhibiting any component of this signaling pathway partially reduced the ability of PTX3 to promote cementoblast differentiation. In conclusion, our study indicated that PTX3 promotes cementum formation and cementoblast differentiation, which is partially dependent on the HA/ITGB1/FAK/YAP1 signaling pathway. This research will contribute to our understanding of cementum regeneration after destruction.

Bioactive polymers: A comprehensive review on bone grafting biomaterials

The application of bone grafting materials in bone tissue engineering is paramount for treating severe bone defects. In this comprehensive review, we explore the significance and novelty of utilizing bioactive polymers as grafts for successful bone repair. Unlike metals and ceramics, polymers offer inherent biodegradability and biocompatibility, mimicking the native extracellular matrix of bone. While these polymeric micro-nano materials may face challenges such as mechanical strength, various fabrication techniques are available to overcome these shortcomings. Our study not only investigates diverse biopolymeric materials but also illuminates innovative fabrication methods, highlighting their importance in advancing bone tissue engineering.

The impact of hyaluronic acid coating on polyether ether ketone dental implant surface: An in vitro analysis

Objective

Polyether ether ketone (PEEK), a biocompatible polymer, is being explored as an alternative to metallic alloys for dental implants due to its aesthetic and mechanical properties. This study aimed to enhance the surface biofunctionality through evaluating human MG-63 osteoblastic cell survival, proliferation, differentiation, and mineralization.

Method

Following the sandblasting and plasma treatment of the 3D-printed PEEK discs, a layer of hyaluronic acid (Hya) was coated onto the PEEK surface. Osteoblast cells were seeded onto the discs. The groups consisted of Hya-coated PEEK, uncoated PEEK, and a control group. Cell viability, proliferation, differentiation, and mineralization potential were examined after seven and twenty-one days of cell seeding using the MTT test, DAPI staining technique, alkaline phosphatase activity (ALP), and alizarin red staining.

Results

Hya-coated PEEK increased cell viability (1.48 ± 0.13, 1.49 ± 0.09) compared to the uncoated group (1.19 ± 0.06, 1.26 ± 0.07) and control group (0.98 ± 0.04, 1.00 ± 0.07) after 7 and 21 days. Proliferation rates of coated group (60.50 ± 3.08) were greater than the uncoated (50.33 ± 2.58) and control group (38.33 ± 4.88) at 21 days, respectively. Additionally, the ALP activity on Hya-coated PEEK disks (5.55 ± 0.65, 7.54 ± 0.64) was notably higher than that of the uncoated group (1.08 ± 0.49, 2.59 ± 0.68), and control group (0.16 ± 0.09, 0.34 ± 0.18) at both time periods. Alizarin red staining in the Hya-coated PEEK group (1.81 ± 0.23, 1.97 ± 0.20) was significantly greater in comparison with uncoated group (1.12 ± 0.17, 1.14 ± 0.19) and control group (0.99 ± 0.10, 0.98 ± 0.05) at both time intervals.

Conclusion

Hya's surface coating has enhanced the biofunctional properties of PEEK implant material, as demonstrated by improved cell survival, proliferation, differentiation, and mineralization potential.

How Is Bone Regeneration Influenced by Polymer Membranes? Insight into the Histological and Radiological Point of View in the Literature

The aim of this study was to analyze published works that investigate the in vivo bone regeneration capacity of polymeric membranes loaded with active substances and growth factors. This scoping review's purpose was to highlight the histological and radiological interpretation of the locally produced effects of the polymer membranes studied so far. For the selection of the articles, a search was made in the PubMed and ScienceDirect databases, according to the PRISMA algorithm, for research/clinical trial type studies. The search strategy was represented by the formula "((biodegradable scaffolds AND critical bone defect) OR (polymers AND mechanical properties) OR (3Dmaterials AND cytotoxicity) AND bone tissue regeneration)" for the PubMed database and "((biodegradable scaffolds AND polymers) OR (polymers AND critical bone defects) OR (biodegradable scaffolds AND mechanical properties) AND bone tissue regeneration)" for the ScienceDirect database. Ethical approval was not required. Eligibility criteria included eight clinical studies published between 2018 and 2023. Our analysis showed that polymer membranes that met most histopathological criteria also produced the most remarkable results observed radiologically. The top effective scaffolds were those containing active macromolecules released conditionally and staged. The PLGA and polycaprolactone scaffolds were found in this category; they granted a marked increase in bone density and improvement of osteoinduction. But, regardless of the membrane composition, all membranes implanted in created bone defects induced an inflammatory response in the first phase.

Multiparametric influence of 3D-printed organo-mineral scaffolds on bone regeneration

The development of synthetic bone substitutes that equal or exceed the efficacy of autologous graft remains challenging. In this study, a rat calvarial defect model was used as a reference to investigate the influence of composition and architecture of 3D-printed cement, with or without bioactives, on tissue regeneration. Printable cement pastes were formulated by combining hyaluronic acid and cement precursors. Cementitious scaffolds were printed with 3 different patterns. After 7 weeks of implantation with or without bone marrow, multiparametric qualitative and quantitative assessments were performed using µCT, SEM, and histology. None of the set-up strategies was as efficient as autologous cancellous bone graft to repair calvarial defects. Nonetheless, the presence of scaffold improved the skull vault closure, particularly when the scaffold was soaked in total bone marrow before implantation. No significant effect of scaffold macro-architecture was observed on tissue mineralization. Magnesium phosphate-based scaffolds (MgP) seemed to induce higher bone formation than their calcium-phosphate-based counterparts. They also displayed a quicker biodegradation and sparse remaining material was found after 7 weeks of implantation. Although further improvements are required to reach clinical settings, this study demonstrated the potential of organo-mineral cements for bone regeneration and highlighted the peculiar properties of MgP-based cements.

Beyond hype: unveiling the Real challenges in clinical translation of 3D printed bone scaffolds and the fresh prospects of bioprinted organoids

Bone defects pose significant challenges in healthcare, with over 2 million bone repair surgeries performed globally each year. As a burgeoning force in the field of bone tissue engineering, 3D printing offers novel solutions to traditional bone transplantation procedures. However, current 3D-printed bone scaffolds still face three critical challenges in material selection, printing methods, cellular self-organization and co-culture, significantly impeding their clinical application. In this comprehensive review, we delve into the performance criteria that ideal bone scaffolds should possess, with a particular focus on the three core challenges faced by 3D printing technology during clinical translation. We summarize the latest advancements in non-traditional materials and advanced printing techniques, emphasizing the importance of integrating organ-like technologies with bioprinting. This combined approach enables more precise simulation of natural tissue structure and function. Our aim in writing this review is to propose effective strategies to address these challenges and promote the clinical translation of 3D-printed scaffolds for bone defect treatment.

Application of Bioactive Materials for Osteogenic Function in Bone Tissue Engineering

Bone tissue defects present a major challenge in orthopedic surgery. Bone tissue engineering using multiple versatile bioactive materials is a potential strategy for bone-defect repair and regeneration. Due to their unique physicochemical and mechanical properties, biofunctional materials can enhance cellular adhesion, proliferation, and osteogenic differentiation, thereby supporting and stimulating the formation of new bone tissue. 3D bioprinting and physical stimuli-responsive strategies have been employed in various studies on bone regeneration for the fabrication of desired multifunctional biomaterials with integrated bone tissue repair and regeneration properties. In this review, biomaterials applied to bone tissue engineering, emerging 3D bioprinting techniques, and physical stimuli-responsive strategies for the rational manufacturing of novel biomaterials with bone therapeutic and regenerative functions are summarized. Furthermore, the impact of biomaterials on the osteogenic differentiation of stem cells and the potential pathways associated with biomaterial-induced osteogenesis are discussed.

Nanofibrous Microspheres: A Biomimetic Platform for Bone Tissue Regeneration

Bone, a fundamental constituent of the human body, is a vital scaffold for support, protection, and locomotion, underscoring its pivotal role in maintaining skeletal integrity and overall functionality. However, factors such as trauma, disease, or aging can compromise bone structure, necessitating effective strategies for regeneration. Traditional approaches often lack biomimetic environments conducive to efficient tissue repair. Nanofibrous microspheres (NFMS) present a promising biomimetic platform for bone regeneration by mimicking the native extracellular matrix architecture. Through optimized fabrication techniques and the incorporation of active biomolecular components, NFMS can precisely replicate the nanostructure and biochemical cues essential for osteogenesis promotion. Furthermore, NFMS exhibit versatile properties, including tunable morphology, mechanical strength, and controlled release kinetics, augmenting their suitability for tailored bone tissue engineering applications. NFMS enhance cell recruitment, attachment, and proliferation, while promoting osteogenic differentiation and mineralization, thereby accelerating bone healing. This review highlights the pivotal role of NFMS in bone tissue engineering, elucidating their design principles and key attributes. By examining recent preclinical applications, we assess their current clinical status and discuss critical considerations for potential clinical translation. This review offers crucial insights for researchers at the intersection of biomaterials and tissue engineering, highlighting developments in this expanding field.

Effect of Platelet-Rich Fibrin Combined With Hyaluronic Acid on Bone Formation in Dental Implant Sockets: An In Vivo Study in Sheep

OBJECTIVES

The goal was to evaluate the effect of the combined growth factor of hyaluronic acid (HA) and advanced platelet-rich fibrin (A-PRF) on acceleration and maturation of bone formation around titanium dental implants in the bone-free space (jumping distance) of an over-preparation socket.

MATERIALS AND METHODS

 Thirty-two titanium dental implants were placed in four sheep and distributed into one control group (A) and three experimental groups (B, C, and D) in two different time periods. Each sheep received eight implants. The eight implants in each sheep were distributed into four groups. The first period was one month after the initial placement, 16 implants were used in two sheep. The second period was three months after the initial placement; another 16 implants were used in the other two sheep. All implants were placed in over-prepared implant sockets, resulting in minimal primary stability. In Group A: the space between the dental implant and the bone of the inner wall of the socket was left without a growth substrate material. In Group B: we added HA between the dental implant and the bone of the inner wall of the socket. In Group C: we added A-PRF between the dental implant and the bone of the inner wall of the socket. In Group D: we added a combination of HA and A-PRF between the dental implant and the bone of the inner wall of the socket. Data was collected for each group at one month and three months at the same time. A high-resolution, desktop micro-CT system (Bruker Skyscan 1275, Kontich, Belgium) was used to scan the specimens. The NRecon software (ver. 1.6.10.4, SkyScan) and CTAn (SkyScan) were used for the visualization and quantitative measurement of the samples. One-way analysis of variance (ANOVA) was used to compare the means of the four study groups in the same period. A post hoc test was used after ANOVA to compare the means of two samples at the same time. A p-value of ≤ 0.05 was considered statistically significant.

RESULTS

After one month and three months of using combined HA and A-PRF on Group D, significant acceleration was observed in bone formation in all tests around dental implants compared with other groups, while no significant acceleration was observed when they were used separately; all three study groups showed significant results when compared with the control group.

CONCLUSION

Our data showed that using a combination of HA and A-PRF had a significant effect on the acceleration of the bone formation and ossification process when added to bone-free space (jumping distance) around implants while leaving space without any growth substrates might delay the bone ossification process.

Hyaluronic Acid/Ellagic Acid as Materials for Potential Medical Application

The aim of this work was to develop and characterize a thin films composed of hyaluronic acid/ellagic acid for potential medical application. Its principal novelty, distinct from the prior literature in terms of hyaluronic acid films supplemented with phenolic acids, resides in the predominant incorporation of ellagic acid-a distinguished compound-as the primary constituent of the films. Herein, ellagic acid was dissolved in two different solvents, i.e., acetic acid (AcOH) or sodium hydroxide (NaOH), and the surface properties of the resultant films were assessed using atomic force microscopy and contact angle measurements. Additionally, various physicochemical parameters were evaluated including moisture content, antioxidant activity, and release of ellagic acid in phosphate buffered saline. Furthermore, the evaluation of films' biocompatibility was conducted using human epidermal keratinocytes, dermal fibroblasts, and human amelanotic melanoma cells (A375 and G361), and the antimicrobial activity was elucidated accordingly against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 15442. Our results showed that the films exhibited prominent antibacterial properties particularly against Staphylococcus aureus, with the 80HA/20EA/AcOH film indicating the strong biocidal activity against this strain leading to a significant reduction in viable cells. Comparatively, the 50HA/50EA/AcOH film also displayed biocidal activity against Staphylococcus aureus. This experimental approach could be a promising technique for future applications in regenerative dermatology or novel strategies in terms of bioengineering.

Towards Stem Cell Therapy for Critical-Sized Segmental Bone Defects: Current Trends and Challenges on the Path to Clinical Translation

The management and reconstruction of critical-sized segmental bone defects remain a major clinical challenge for orthopaedic clinicians and surgeons. In particular, regenerative medicine approaches that involve incorporating stem cells within tissue engineering scaffolds have great promise for fracture management. This narrative review focuses on the primary components of bone tissue engineering-stem cells, scaffolds, the microenvironment, and vascularisation-addressing current advances and translational and regulatory challenges in the current landscape of stem cell therapy for critical-sized bone defects. To comprehensively explore this research area and offer insights for future treatment options in orthopaedic surgery, we have examined the latest developments and advancements in bone tissue engineering, focusing on those of clinical relevance in recent years. Finally, we present a forward-looking perspective on using stem cells in bone tissue engineering for critical-sized segmental bone defects.

Exploring the Progress of Hyaluronic Acid Hydrogels: Synthesis, Characteristics, and Wide-Ranging Applications

This comprehensive review delves into the world of hyaluronic acid (HA) hydrogels, exploring their creation, characteristics, research methodologies, and uses. HA hydrogels stand out among natural polysaccharides due to their distinct features. Their exceptional biocompatibility makes them a top choice for diverse biomedical purposes, with a great ability to coexist harmoniously with living cells and tissues. Furthermore, their biodegradability permits their gradual breakdown by bodily enzymes, enabling the creation of temporary frameworks for tissue engineering endeavors. Additionally, since HA is a vital component of the extracellular matrix (ECM) in numerous tissues, HA hydrogels can replicate the ECM's structure and functions. This mimicry is pivotal in tissue engineering applications by providing an ideal setting for cellular growth and maturation. Various cross-linking techniques like chemical, physical, enzymatic, and hybrid methods impact the mechanical strength, swelling capacity, and degradation speed of the hydrogels. Assessment tools such as rheological analysis, electron microscopy, spectroscopy, swelling tests, and degradation studies are employed to examine their attributes. HA-based hydrogels feature prominently in tissue engineering, drug distribution, wound recovery, ophthalmology, and cartilage mending. Crafting HA hydrogels enables the production of biomaterials with sought-after qualities, offering avenues for advancements in the realm of biomedicine.

Recent Advances in the Degradability and Applications of Tissue Adhesives Based on Biodegradable Polymers

In clinical practice, tissue adhesives have emerged as an alternative tool for wound treatments due to their advantages in ease of use, rapid application, less pain, and minimal tissue damage. Since most tissue adhesives are designed for internal use or wound treatments, the biodegradation of adhesives is important. To endow tissue adhesives with biodegradability, in the past few decades, various biodegradable polymers, either natural polymers (such as chitosan, hyaluronic acid, gelatin, chondroitin sulfate, starch, sodium alginate, glucans, pectin, functional proteins, and peptides) or synthetic polymers (such as poly(lactic acid), polyurethanes, polycaprolactone, and poly(lactic-co-glycolic acid)), have been utilized to develop novel biodegradable tissue adhesives. Incorporated biodegradable polymers are degraded in vivo with time under specific conditions, leading to the destruction of the structure and the further degradation of tissue adhesives. In this review, we first summarize the strategies of utilizing biodegradable polymers to develop tissue adhesives. Furthermore, we provide a symmetric overview of the biodegradable polymers used for tissue adhesives, with a specific focus on the degradability and applications of these tissue adhesives. Additionally, the challenges and perspectives of biodegradable polymer-based tissue adhesives are discussed. We expect that this review can provide new inspirations for the design of novel biodegradable tissue adhesives for biomedical applications.

Hyaluronan in mesenchymal stromal cell lineage differentiation from human pluripotent stem cells: application in serum free culture

BACKGROUND

Hyaluronan (HA) is an extracellular glycosaminoglycan polysaccharide with widespread roles throughout development and in healthy and neoplastic tissues. In pluripotent stem cell culture it can support both stem cell renewal and differentiation. However, responses to HA in culture are influenced by interaction with a range of cognate factors and receptors including components of blood serum supplements, which alter results. These may contribute to variation in cell batch production yield and phenotype as well as heighten the risks of adventitious pathogen transmission in the course of cell processing for therapeutic applications. MAIN: Here we characterise differentiation of a human embryo/pluripotent stem cell derived Mesenchymal Stromal Cell (hESC/PSC-MSC)-like cell population by culture on a planar surface coated with HA in serum-free media qualified for cell production for therapy. Resulting cells met minimum criteria of the International Society for Cellular Therapy for identification as MSC by expression of. CD90, CD73, CD105, and lack of expression for CD34, CD45, CD14 and HLA-II. They were positive for other MSC associated markers (i.e.CD166, CD56, CD44, HLA 1-A) whilst negative for others (e.g. CD271, CD71, CD146). In vitro co-culture assessment of MSC associated functionality confirmed support of growth of hematopoietic progenitors and inhibition of mitogen activated proliferation of lymphocytes from umbilical cord and adult peripheral blood mononuclear cells, respectively. Co-culture with immortalized THP-1 monocyte derived macrophages (Mɸ) concurrently stimulated with lipopolysaccharide as a pro-inflammatory stimulus, resulted in a dose dependent increase in pro-inflammatory IL6 but negligible effect on TNFα. To further investigate these functionalities, a bulk cell RNA sequence comparison with adult human bone marrow derived MSC and hESC substantiated a distinctive genetic signature more proximate to the former.

CONCLUSION

Cultivation of human pluripotent stem cells on a planar substrate of HA in serum-free culture media systems is sufficient to yield a distinctive developmental mesenchymal stromal cell lineage with potential to modify the function of haematopoietic lineages in therapeutic applications.

Preparation of nano-silver containing black phosphorus based on quaternized chitosan hydrogel and evaluating its effect on skin wound healing

Hydrogels with favorable biocompatibility and antibacterial properties are essential in postoperative wound hemorrhage care, facilitating rapid wound healing. The present investigation employed electrostatic adsorption of black phosphorus nanosheets (BPNPs) and nano‑silver (AgNPs) to cross-link the protonated amino group NH3+ of quaternized chitosan (QCS) with the hydroxyl group of hyaluronic acid (HA). The electrostatic interaction between the two groups resulted in the formation of a three-dimensional gel network structure. Additionally, the hydrogel containing AgNPs deposited onto BPNPs was assessed for its antibacterial properties and effects on wound healing. Hydrogel demonstrated an outstanding drug-loading capacity and could be employed for wound closure. AgNPs loaded on the BPNPs released silver ions and exhibited potent antibacterial properties when exposed to 808 nm near-infrared (NIR) radiation. The ability of the hydrogel to promote wound healing in an acute wound model was further evaluated. The BPNPs were combined with HA and QCS in the aforementioned hydrogel system to improve adhesion, combine the photothermal and antibacterial properties of the BPNPs, and promote wound healing. Therefore, the reported hydrogels displayed excellent biocompatibility and hold significant potential for application in the field of tissue engineering for skin wound treatment.

High-Performance Hydrogel-Encapsulated Engineered Exosomes for Supporting Endoplasmic Reticulum Homeostasis and Boosting Diabetic Bone Regeneration

The regeneration of bone defects in diabetic patients still faces challenges, as the intrinsic healing process is impaired by hyperglycemia. Inspired by the discovery that the endoplasmic reticulum (ER) is in a state of excessive stress and dysfunction under hyperglycemia, leading to osteogenic disorder, a novel engineered exosome is proposed to modulate ER homeostasis for restoring the function of mesenchymal stem cells (MSCs). The results indicate that the constructed engineered exosomes efficiently regulate ER homeostasis and dramatically facilitate the function of MSCs in the hyperglycemic niche. Additionally, the underlying therapeutic mechanism of exosomes is elucidated. The results reveal that exosomes can directly provide recipient cells with SHP2 for the activation of mitophagy and elimination of mtROS, which is the immediate cause of ER dysfunction. To maximize the therapeutic effect of engineered exosomes, a high-performance hydrogel with self-healing, bioadhesive, and exosome-conjugating properties is applied to encapsulate the engineered exosomes for in vivo application. In vivo, evaluation in diabetic bone defect repair models demonstrates that the engineered exosomes delivering hydrogel system intensively enhance osteogenesis. These findings provide crucial insight into the design and biological mechanism of ER homeostasis-based tissue-engineering strategies for diabetic bone regeneration.