Biomaterial-based scaffolds in promotion of cartilage regeneration: Recent advances and emerging applications

Nanotechnology-Assisted mesenchymal stem cells treatment for improved cartilage regeneration: A review of current practices

Cartilage tissue does not promptly elicit an inflammatory response upon injury, hence constraining its capacity for healing and self-regeneration. Mesenchymal Stem Cells (MSC) therapy, enhanced by nanotechnology, offers promising advancements in cartilage repair. Injuries to cartilage often cause chronic pain, where current treatments are inadequate. As MSCs can readily differentiate into chondrocytes and secrete soluble factors, they are essential components in tissue engineering of cartilage repair. Although, like other stem cell applications, clinical applications are restricted by poor post implantation survival and differentiation. Recent studies show that nanoparticles (NPs) can further improve MSC outcomes by promoting cell adhesion, and chondrogenic differentiation allowing for sustained growth factor release. In addition, nanomaterials can improve the biological activity of MSCs, by also facilitating the composition of a conducive microenvironment for cartilage repair. In this review, the application of nanofibrous scaffolds, hydrogels and nanoscale particulate matter to improve mechanical properties in cartilage tissue engineering, are discussed. Moreover, the MSCs and nanotechnology synergistic effects present hope of overcoming the limitations of conventional treatments. Nanotechnology greatly enhances the MSC based cartilage regeneration strategies and could provide better treatment for cartilage related diseases in the future. Future research should be aimed at standardizing MSC harvesting and culturing protocols and contrasting their long-term efficacy.

Immunomodulation Effects of Porcine Cartilage Acellularized Matrix (pCAM) for Osteoarthritis Treatment

BACKGROUND

Pain reduction, immunomodulation, and cartilage repair are key therapeutic goals in osteoarthritis (OA) treatment. In this study, we evaluated the therapeutic effects of porcine cartilage acellularized matrix (pCAM) derived from naive tissue and compared it with the synthetic material polynucleotides (PN) for OA treatment.

METHODS

pCAM was produced from porcine cartilage through physicochemical processing. LC-MS protein profiling identified the key proteins. In vitro experiments involved treating human synovial cell with pCAM and PN to assess cell viability and reductions in pro-inflammatory cytokines (IL-1β and IL-6). In vivo studies utilized a rat DMM-induced OA model. Pain was evaluated in weight-bearing tests, and inflammation reduction was confirmed using specific macrophage markers of CD68, CD86, and CD163 in immunohistochemical staining of synovial tissue. Cartilage regeneration was evaluated by histopathological analyses.

RESULTS

The major protein components of pCAM include factors integral to cartilage and ECM integrity. They also contain proteins that help reduce inflammation. In vitro studies revealed a decrease in pro-inflammatory cytokines and survival of synovial cells were observed. In vivo treatment with pCAM resulted in a reduction of pain and inflammation, while promoting cartilage regeneration, thereby accelerating the healing process in OA.

CONCLUSION

Our findings suggest that pCAM may contribute to the treatment of OA by alleviating synovial inflammation and supporting cartilage regeneration, thereby addressing both the inflammatory and degenerative aspects of the disease.

Three-Dimensional-Printed Bone Grafts for Simultaneous Bone and Cartilage Regeneration: A Promising Approach to Osteochondral Tissue Engineering

Background/Objectives: A novel 3D-printed, bioresorbable bone graft, made of nanohydroxyapatite (nHAP) covered by poly(lactide-co-glycolide) (PLGA), showed strongly expressed osteoinductive properties in our previous investigations. The current study examines its application in the dual regeneration of bone and cartilage by combining with nHAP gel obtained by nHAP enrichment with hydroxyethyl cellulose, sodium hyaluronate, and chondroitin sulfate. Methods: In the in vitro part of the study, the mitochondrial activity and osteogenic and chondrogenic differentiation of stem cells derived from apical papilla (SCAPs) in the presence of nHAP gel were investigated. For the in vivo part of the study, three rabbits underwent segmental osteotomies of the lateral condyle of the femur, and defects were filled by 3D-printed grafts customized to the defect geometry. Results: In vitro study revealed that nHAP gel displayed significant biocompatibility, substantially increasing mitochondrial activity and facilitating the osteogenic and chondrogenic differentiation of SCAPs. For the in vivo part of the study, after a 12-week healing period, partial resorption of the graft was observed, and lamellar bone tissue with Haversian systems was detected. Histological and stereological evaluations of the implanted grafts indicated successful bone regeneration, marked by the infiltration of new bone and cartilaginous tissue into the graft. The existence of osteocytes and increased vascularization indicated active osteogenesis. The hyaline cartilage near the graft showed numerous new chondrocytes and a significant layer of newly formed cartilage. Conclusions: This study demonstrated that tailored 3D-printed bone grafts could efficiently promote the healing of substantial bone defects and the formation of new cartilage without requiring supplementary biological factors, offering a feasible alternative for clinical bone repair applications.

Biologic Augmented Scaffold-based cartilage repair: Addressing Complications and Enhancing Outcomes

Cartilage repair remains a significant challenge due to the tissue's limited innate regenerative capacity. Despite advances in techniques such as microfracture, autologous chondrocyte implantation (ACI), and osteochondral grafting, long-term outcomes are often compromised by complications, including suboptimal tissue integration, graft resorption, and mechanical instability. Recently, biologically augmented scaffold-based cartilage repair has emerged as a promising approach for full-thickness osteochondral lesions. These techniques combine acellular scaffolds with biologic agents, such as bone marrow aspirate concentrates (BMAC), to enhance tissue regeneration, reduce inflammation, and promote healing. However, postoperative complications-such as graft hypertrophy, arthrofibrosis, graft hypotrophy, and graft dislodgement-continue to pose challenges to successful outcomes. This paper presents case studies illustrating the clinical presentation, diagnosis, and management of these complications. Early recognition through clinical evaluation and imaging, followed by timely intervention, proved essential in mitigating the long-term effects of these complications. Although biologically augmented scaffolds offer potential advantages, variability in outcomes remains due to differences in biologic composition, scaffold design, and patient factors. The findings highlight the importance of individualized treatment strategies and adherence to postoperative rehabilitation protocols to reduce the risk of complications. Further research is needed to optimize biologic augmentation protocols and scaffold designs to improve long-term cartilage repair outcomes.

Effects of electric fields on the modulation of chondrocytes dynamics in gelatin scaffolds: a novel approach to optimize cartilage tissue engineering

The treatment of degenerative pathologies affecting articular cartilage remains a significant clinical challenge. Non-invasive biophysical stimuli, such as electric fields, have demonstrated potential as therapeutic tools for cartilage tissue restoration. Previous studies have reported that electric fields enhance chondrocyte proliferation and the synthesis of key extracellular matrix components, such as glycosaminoglycans. However, inconsistencies in experimental designs have led to variable findings. This study examines the effects of capacitively coupled electric fields on chondrocytes cultured in gelatin hydrogels. Alternating voltages of 50 V (7.7 mV/cm) and 100 V (8.7 mV/cm) at a frequency of 60 kHz were applied for 21 days. Cell quantification and glycosaminoglycan analysis were performed on both stimulated and control samples. On day 7, exposure to the electric field resulted in a significant reduction in cell proliferation by 24.7% and 39.2% at 7.7 mV/cm and 8.7 mV/cm, respectively (p < 0.05). However, stimulation at 8.7 mV/cm led to a 35.7% increase in glycosaminoglycan synthesis compared to the control group (p < 0.05). These findings indicate that electric field stimulation can modulate the synthesis of essential extracellular matrix components, such as glycosaminoglycans, in hyaline cartilage. This highlights the potential of electric fields as a promising strategy to enhance outcomes in articular cartilage tissue engineering, particularly in hydrogel-based therapeutic approaches.

A miR-activated hydrogel for the delivery of a pro-chondrogenic microRNA-221 inhibitor as a minimally invasive therapeutic approach for articular cartilage repair

Articular cartilage has limited capacity for repair (or for regeneration) under pathological conditions, given its non-vascularized connective tissue structure and low cellular density. Our group has successfully developed an injectable hydrogel for cartilage repair, composed of collagen type I (Col I), collagen type II (Col II), and methacrylated-hyaluronic acid (MeHA), capable of supporting chondrogenic differentiation of mesenchymal stem cells (MSCs) towards articular cartilage-like phenotypes. Recent studies have demonstrated that silencing miR-221 may be an effective approach in promoting improved MSC chondrogenesis. Thus, this study aimed to develop a miR-activated hydrogel capable of offering a more effective and less invasive therapeutic approach to articular cartilage repair by delivering a pro-chondrogenic miR-221 inhibitor to MSCs using our MeHA-Col I/Col II hydrogel. The MeHA-Col I/Col II hydrogel was cast as previously shown and incorporated with cells transfected with miR-221 inhibitor (using a non-viral peptide delivery vector) to produce the miR-activated hydrogel. Down-regulation of miR-221 did not affect cell viability and enhanced MSCs-mediated chondrogenesis, as evidenced by significantly upregulated expression of key pro-chondrogenic articular cartilage genes (COL2A1 and ACAN) without promoting hypertrophic events (RUNX2 and COL10A1). Furthermore, miR-221 down-regulation improved cartilage-like matrix formation in the MeHA-Col I/Col II hydrogel, with significantly higher levels of sulfated glycosaminoglycans (sGAG) and Col II produced by MSCs in the hydrogel. These results provide evidence of the potential of the miR-activated hydrogel as a minimally invasive therapeutic strategy for articular cartilage repair.

Wharton's Jelly Mesenchymal Stem Cells: Shaping the Future of Osteoarthritis Therapy with Advancements in Chitosan-Hyaluronic Acid Scaffolds

This review explores the potential of Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) in cartilage regeneration and osteoarthritis treatment. It covers key factors influencing chondrogenesis, including growth factors, cytokines, and hypoxia, focusing on precise timing. The effectiveness of three-dimensional cultures and scaffold-based strategies in chondrogenic differentiation is discussed. Specific biomaterials such as chitosan and hyaluronic acid are highlighted for tissue engineering. The document reviews clinical applications, incorporating evidence from animal research and early trials and molecular and histological assessments of chondrogenic differentiation processes. It addresses challenges and strategies for optimizing MSC-derived chondrocyte therapy, emphasizing the immunomodulatory properties of these cells. The review concludes as a comprehensive road map for future research and clinical applications in regenerative medicine.

Biomimetic multizonal scaffolds for the reconstruction of zonal articular cartilage in chondral and osteochondral defects

Chondral and osteochondral injuries are frequently encountered in clinical practice. However, articular cartilage has limited self-healing capacity due to its sophisticated zonal structure and avascular nature, introducing significant challenges to the restoration of chondral and osteochondral tissues after injury. Improperly repaired articular cartilage can lead to irreversible joint damage and increase the risk of osteoarthritis progression. Cartilage tissue engineering using stratified scaffolds with multizonal design to match the zonal structure of articular cartilage may help to meet the complex regeneration requirements of chondral and osteochondral tissues, and address the drawbacks experienced with single-phase scaffolds. Navigating the heterogeneity in matrix organisation and cellular composition across cartilage zones is a central consideration in multizonal scaffold design. With emphasis on recent advances in scaffold design and fabrication strategies, this review captures emerging approaches on biomimetic multizonal scaffolds for the reconstruction of zonal articular cartilage, including strategies on replicating native tissue structure through variations in fibre orientation, porous structure, and cell types. Exciting progress in this dynamic field has highlighted the tremendous potential of multizonal scaffolding strategies for regenerative medicine in the recreation of functional tissues.

Research advance of 3D printing for articular cartilage regeneration

Articular cartilage lesion frequently leads to dysfunction and the development of degenerative diseases, posing a significant public health challenge due to the limited self-healing capacity of cartilage tissue. Current surgical treatments, including marrow stimulation techniques and osteochondral autografts/allografts, have limited efficacy or have significant drawbacks, highlighting the urgent need for alternative strategies. Advances in 3D printing for cartilage regeneration have shown promising potential in creating cartilage-mimicking constructs, thereby opening new possibilities for cartilage repair. In this review, we summarize current surgical treatment methods and their limitations for addressing articular cartilage lesion, various 3D printing strategies and their features in cartilage tissue engineering, seed cells from different sources, and different types of biomaterials. We also explore the benefits, current challenges, and future research directions for 3D printing in the treatment of articular cartilage lesion within the field of cartilage tissue engineering.

Forty Years of the Use of Cells for Cartilage Regeneration: The Research Side

Background: The treatment of articular cartilage damage has always represented a problem of considerable practical interest for orthopedics. Over the years, many surgical techniques have been proposed to induce the growth of repairing tissue and limit degeneration. In 1994, the turning point occurred: implanted autologous cells paved the way for a new treatment option based more on regeneration than repair. Objectives: This review aims to outline biological and clinical advances, from the use of mature adult chondrocytes to cell-derived products, going through progenitor cells derived from bone marrow or adipose tissue and their concentrates for articular cartilage repair. Moreover, it highlights the relevance of gene therapy as a valuable tool for successfully implementing current regenerative treatments, and overcoming the limitations of the local delivery of growth factors. Conclusions: Finally, this review concludes with an outlook on the importance of understanding the role and mechanisms of action of the different cell compounds with a view to implementing personalized treatments.

3D-printed constructs deliver bioactive cargos to expedite cartilage regeneration

Cartilage is solid connective tissue that recovers slowly from injury, and pain and dysfunction from cartilage damage affect many people. The treatment of cartilage injury is clinically challenging and there is no optimal solution, which is a hot research topic at present. With the rapid development of 3D printing technology in recent years, 3D bioprinting can better mimic the complex microstructure of cartilage tissue and thus enabling the anatomy and functional regeneration of damaged cartilage. This article reviews the methods of 3D printing used to mimic cartilage structures, the selection of cells and biological factors, and the development of bioinks and advances in scaffold structures, with an emphasis on how 3D printing structure provides bioactive cargos in each stage to enhance the effect. Finally, clinical applications and future development of simulated cartilage printing are introduced, which are expected to provide new insights into this field and guide other researchers who are engaged in cartilage repair.

Innovative hydrogel solutions for articular cartilage regeneration: a comprehensive review

Articular cartilage damage is predominantly caused by trauma, osteoarthritis (OA), and other pathological conditions. The limited intrinsic capacity of cartilage tissue to self-repair necessitates timely intervention following acute injuries to prevent accelerated degeneration, leading to the development of planar arthritis or even osteoarthritis. Unfortunately, current therapies for articular cartilage damage are inadequate in effectively replacing or regenerating compromised cartilage due to the absence of suitable tissue-engineered artificial matrices. However, there is promise in utilizing hydrogels, a category of biomaterials characterized by their elasticity, smooth surfaces, and high water content, for cartilage regeneration. Recent advancements in hydrogel engineering have focused on improving their bioactive and physicochemical properties, encompassing innovative composition designs, dynamic modulation, and intricate architectures. This review provides a comprehensive analysis of hydrogels for articular cartilage repair, focusing on their innovative design, clinical applications, and future research directions. By integrating insights from the latest research studies and clinical trials, the review offers a unique perspective on the translation of hydrogels for articular cartilage repair, underscoring their potential as promising therapeutic agents.

Mesenchymal Stromal Cells for Aging Cartilage Regeneration: A Review

Cartilage degeneration is a key feature of aging and osteoarthritis, characterized by the progressive deterioration of joint function, pain, and limited mobility. Current treatments focus on symptom relief, not cartilage regeneration. Mesenchymal stromal cells (MSCs) offer a promising therapeutic option due to their capability to differentiate into chondrocytes, modulate inflammation, and promote tissue regeneration. This review explores the potential of MSCs for cartilage regeneration, examining their biological properties, action mechanisms, and applications in preclinical and clinical settings. MSCs derived from bone marrow, adipose tissue, and other sources can self-renew and differentiate into multiple cell types. In aging cartilage, they aid in tissue regeneration by secreting growth factors and cytokines that enhance repair and modulate immune responses. Recent preclinical studies show that MSCs can restore cartilage integrity, reduce inflammation, and improve joint function, although clinical translation remains challenging due to limitations such as cell viability, scalability, and regulatory concerns. Advancements in MSC delivery, including scaffold-based approaches and engineered exosomes, may improve therapeutic effectiveness. Potential risks, such as tumorigenicity and immune rejection, are also discussed, emphasizing the need for optimized treatment protocols and large-scale clinical trials to develop effective, minimally invasive therapies for cartilage regeneration.

In Vitro Investigation of 3D Printed Hydrogel Scaffolds with Electrospun Tidemark Component for Modeling Osteochondral Interface

Osteochondral (OC) tissue plays a crucial role due to its ability to connect bone and cartilage tissues. To address the complexity of structure and functionality at the bone-cartilage interface, relevant to the presence of the tidemark as a critical element at the bone-cartilage boundary, we fabricated graded scaffolds through sequential 3D printing. The scaffold's bottom layer was based on a gelatin/oxidized alginate mixture enriched with hydroxyapatite (HAp) to create a rougher surface and larger pores to promote osteogenesis. In contrast, the upper layer was engineered to have smaller pores and aimed to promote cartilage tissue formation and mimic the physical properties of the cartilage. An electrospun ε-polycaprolactone (PCL) membrane with micrometer-range pores was incorporated between the layers to replicate the function of tidemark-a barrier to prevent vascularization of cartilage from subchondral bone tissue. In vitro cell studies confirmed the viability of the cells on the layers of the scaffolds and the ability of PCL mesh to prevent cellular migration. The fabricated scaffolds were thoroughly characterized, and their mechanical properties were compared to native OC tissue, demonstrating suitability for OC tissue engineering and graft modeling. The distance of gradient of mineral concentration was found to be 151 µm for grafts and the native OC interface.

Edge advances in nanodrug therapies for osteoarthritis treatment

As global population and lifestyles change, osteoarthritis (OA) is becoming a major healthcare challenge world. OA, a chronic condition characterized by inflammatory and degeneration, often present with joint pain and can lead to irreversible disability. While there is currently no cure for OA, it is commonly managed using nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, and glucosamine. Although these treatments can alleviate symptoms, it is difficult to effectively deliver and sustain therapeutic agents within joints. The emergence of nanotechnology, particularly in form of smart nanomedicine, has introduced innovative therapeutic approaches for OA treatment. Nanotherapeutic strategies offer promising advantages, including more precise targeting of affected areas, prolonged therapeutic effects, enhanced bioavailability, and reduced systemic toxicity compared to traditional treatments. While nanoparticles show potential as a viable delivery system for OA therapies based on encouraging lab-based and clinical trials results, there remails a considerable gap between current research and clinical application. This review highlights recent advances in nanotherapy for OA and explore future pathways to refine and optimize OA treatments strategies.

Chondrogenic Potential of Umbilical Cord-Derived Mesenchymal Stromal Cells: Insights and Innovations

BACKGROUND

The advent of tissue engineering and regenerative medicine has introduced innovative approaches to treating degenerative and traumatic injuries, particularly in cartilage, a tissue with limited self-repair capabilities. Among the various stem cell sources, umbilical cord-derived mesenchymal stromal cells (UC-MSCs) have garnered significant interest due to their non-invasive collection, minimal ethical concerns, and robust regenerative potential, particularly in cartilage regeneration.

METHODS

A comprehensive literature review was conducted using multiple databases, including PubMed, Scopus, Web of Science, and Google Scholar. Search terms focused on "umbilical cordderived mesenchymal stromal cells," "chondrogenesis," "cartilage regeneration," and related topics. Studies published in the past two decades were included, with selection criteria emphasizing methodological rigor and relevance to UC-MSC chondrogenesis. The review synthesizes findings from various sources to provide a thorough analysis of the potential of UC-MSCs in cartilage tissue engineering.

RESULTS

UC-MSCs exhibit significant chondrogenic potential, supported by their ability to differentiate into chondrocytes under specific conditions. Recent advancements include the development of biomaterial scaffolds and the application of genetic engineering techniques, such as CRISPR/Cas9, to enhance chondrogenic differentiation. Despite these advancements, challenges remain in standardizing cell isolation techniques, scaling up production for clinical use, and ensuring the long-term functionality of regenerated cartilage.

CONCLUSION

UC-MSCs offer a promising solution for cartilage regeneration in the field of regenerative medicine. Ongoing research is focused on overcoming current challenges through the use of advanced technologies, including bioreactors and gene editing. Collaborative efforts among researchers, clinicians, and bioengineers are essential to translating the potential of UC-MSCs into effective clinical therapies, which could significantly advance tissue regeneration and therapeutic innovation.

Angiogenesis unveiled: Insights into its role and mechanisms in cartilage injury

Osteoarthritis (OA) commonly results in compromised mobility and disability, thereby imposing a significant burden on healthcare systems. Cartilage injury is a prevalent pathological manifestation in OA and constitutes a central focus for the development of treatment strategies. Despite the considerable number of studies aimed at delaying this degenerative process, their outcomes remain unvalidated in preclinical settings. Recently, therapeutic strategies focused on angiogenesis have attracted the growing interest from researchers. Thus, we conducted a comprehensive literature review to elucidate the current progress in research and pinpoint research gaps in this domain. Additionally, it provides theoretical guidance for future research endeavors and the development of treatment strategies.

Biomaterials Mimicking Mechanobiology: A Specific Design for a Specific Biological Application

Mechanosensing and mechanotransduction pathways between the Extracellular Matrix (ECM) and cells form the essential crosstalk that regulates cell homeostasis, tissue development, morphology, maintenance, and function. Understanding these mechanisms involves creating an appropriate cell support that elicits signals to guide cellular functions. In this context, polymers can serve as ideal molecules for producing biomaterials designed to mimic the characteristics of the ECM, thereby triggering responsive mechanisms that closely resemble those induced by a natural physiological system. The generated specific stimuli depend on the different natural or synthetic origins of the polymers, the chemical composition, the assembly structure, and the physical and surface properties of biomaterials. This review discusses the most widely used polymers and their customization to develop biomaterials with tailored properties. It examines how the characteristics of biomaterials-based polymers can be harnessed to replicate the functions of biological cells, making them suitable for biomedical and biotechnological applications.

Sodium alginate hydrogels co-encapsulated with cell free fat extract-loaded core-shell nanofibers and menstrual blood stem cells derived exosomes for acceleration of articular cartilage regeneration

This study presents a novel scaffold system comprising sodium alginate hydrogels (SAh) co-encapsulated with cell-free fat extract (CEFFE)-loaded core-shell nanofibers (NFs) and menstrual blood stem cell-derived exosomes (EXOs). The scaffold integrates the regenerative potential of EXOs and CFFFE, offering a multifaceted strategy for promoting articular cartilage repair. Coaxially electrospun core-shell NFs exhibited successful encapsulation of CEFFE and seamless integration into the SAh matrix. Structural modifications induced by the incorporation of CEFFE-NFs enhanced hydrogel porosity, mechanical strength, and degradation kinetics, facilitating cell adhesion, proliferation, and tissue ingrowth. The release kinetics of growth factors from the composite scaffold demonstrated sustained and controlled release profiles, essential for optimal tissue regeneration. In vitro studies revealed high cell viability, enhanced chondrocyte proliferation, and migration in the presence of EXOs/CEFFE-NFs@SAh composite scaffolds. Additionally, in vivo experiments demonstrated significant cartilage regeneration, with the composite scaffold outperforming controls in promoting hyaline cartilage formation and defect bridging. Overall, this study underscores the potential of EXOs and CEFFE-NFs integrated into SAh matrices for enhancing chondrocyte viability, proliferation, migration, and ultimately, articular cartilage regeneration. Future research directions may focus on elucidating underlying mechanisms and conducting long-term in vivo studies to validate clinical applicability and scalability.

Harnessing Corneal Stromal Regeneration for Vision Restoration: A Comprehensive Review of the Emerging Treatment Techniques for Keratoconus

Keratoconus is a progressive corneal disorder characterized by thinning and conical protrusion, leading to visual impairment that often necessitates advanced treatment strategies. Traditional management options, including corrective lenses, corneal cross-linking (CXL), and surgical interventions such as corneal transplants and intracorneal ring segments (ICRS), address symptoms but have limitations, especially in progressive or advanced cases. Recent advancements in corneal stromal regeneration offer promising alternatives for enhancing vision restoration and halting disease progression. This review explores emerging techniques focused on corneal stromal regeneration, emphasizing cell-based therapies, tissue engineering, and gene therapy. Cell-based approaches, including corneal stromal stem cells and adipose-derived stem cells, are promising to promote tissue repair and functional recovery. Tissue engineering techniques, such as developing synthetic and biological scaffolds and 3D bioprinting, are being investigated for their ability to create viable corneal grafts and implants. Additionally, gene therapy and molecular strategies, including gene editing technologies and the application of growth factors, are advancing the potential for targeted treatment and regenerative medicine. Despite these advancements, challenges remain, including technical limitations, safety concerns, and ethical considerations. This review aims to provide a comprehensive overview of these innovative approaches, highlighting their current status, clinical outcomes, and future directions in keratoconus management.

Artificial keloid skin models: understanding the pathophysiological mechanisms and application in therapeutic studies

Keloid is a type of scar formed by the overexpression of extracellular matrix substances from fibroblasts following inflammation after trauma. The existing keloid treatment methods include drug injection, surgical intervention, light exposure, cryotherapy, etc. However, these methods have limitations such as recurrence, low treatment efficacy, and side effects. Consequently, studies are being conducted on the treatment of keloids from the perspective of inflammatory mechanisms. In this study, keloid models are created to understand inflammatory mechanisms and explore treatment methods to address them. While previous studies have used animal models with gene mutations, chemical treatments, and keloid tissue transplantation, there are limitations in fully reproducing the characteristics of keloids unique to humans, and ethical issues related to animal welfare pose additional challenges. Consequently, studies are underway to create in vitro artificial skin models to simulate keloid disease and apply them to the development of treatments for skin diseases. In particular, herein, scaffold technologies that implement three-dimensional (3D) full-thickness keloid models are introduced to enhance mechanical properties as well as biological properties of tissues, such as cell proliferation, differentiation, and cellular interactions. It is anticipated that applying these technologies to the production of artificial skin for keloid simulation could contribute to the development of inflammatory keloid treatment techniques in the future.

Implants coating strategies for antibacterial treatment in fracture and defect models: A systematic review of animal studies

Objective

Fracture-related infection (FRI) remains a major concern in orthopaedic trauma. Functionalizing implants with antibacterial coatings are a promising strategy in mitigating FRI. Numerous implant coatings have been reported but the preventive and therapeutic effects vary. This systematic review aimed to provide a comprehensive overview of current implant coating strategies to prevent and treat FRI in animal fracture and bone defect models.

Methods

A literature search was performed in three databases: PubMed, Web of Science and Embase, with predetermined keywords and criteria up to 28 February 2023. Preclinical studies on implant coatings in animal fracture or defect models that assessed antibacterial and bone healing effects were included.

Results

A total of 14 studies were included in this systematic review, seven of which used fracture models and seven used defect models. Passive coatings with bacteria adhesion resistance were investigated in two studies. Active coatings with bactericidal effects were investigated in 12 studies, four of which used metal ions including Ag+ and Cu2+; five studies used antibiotics including chlorhexidine, tigecycline, vancomycin, and gentamicin sulfate; and the other three studies used natural antibacterial materials including chitosan, antimicrobial peptides, and lysostaphin. Overall, these implant coatings exhibited promising efficacy in antibacterial effects and bone formation.

Conclusion

Antibacterial coating strategies reduced bacterial infections in animal models and favored bone healing in vivo. Future studies of implant coatings should focus on optimal biocompatibility, antibacterial effects against multi-drug resistant bacteria and polymicrobial infections, and osseointegration and osteogenesis promotion especially in osteoporotic bone by constructing multi-functional coatings for FRI therapy.

The translational potential of this paper

The clinical treatment of FRI is complex and challenging. This review summarizes novel orthopaedic implant coating strategies applied to FRI in preclinical studies, and offers a perspective on the future development of orthopaedic implant coatings, which can potentially contribute to alternative strategies in clinical practice.