Search Results (604)

Osteoarthritis (OA) causes chronic pain and impaired mobility in dogs. Since current therapies cannot restore damaged articular cartilage, tissue engineering approaches offer promising therapeutic strategies. This study aimed to investigate whether peri-ovarian adipose tissue (POAT) represents a biologically competent and functionally relevant alternative source of mesenchymal stromal cells (MSCs) compared to subcutaneous adipose tissue (SAT). Samples were collected from five healthy and normal-weight Labrador Retrievers undergoing routine ovariectomy. MSCs were characterized according to the International Society for Cellular Therapy, including doubling time, growth curves, colony-forming unit assays, immunophenotyping, and trilineage differentiation potential. Chondrogenic differentiation was assessed through Alcian Blue staining and qPCR analysis of COL2A1, COL1A1, COL10A1, and SOX9 expression at multiple timepoints. MSCs derived from both adipose depots showed comparable mesenchymal characteristics, proliferative capacity, immunophenotypic profiles, and multilineage differentiation potential. POAT-MSCs exhibited enhanced chondrogenic differentiation compared to SAT-MSCs, with stronger extracellular matrix deposition and significantly increased COL2A1 expression at later stages of differentiation than SAT-MSCs. SOX9 expression supported a more advanced chondrogenic commitment in POAT-derived cells, while COL10A1 expression remained low and stable in both groups. These preliminary findings suggest that POAT, routinely discarded after ovariectomy, may represent a promising and ethically advantageous source of canine MSCs for regenerative medicine. Full article

Scaffolds designed for mechanically demanding soft tissue engineering applications should integrate mechanical support, efficient mass transfer, and good cellular compatibility. This work presents a one-pot method based on “radical-free click chemistry + carbodiimide coupling” to produce a double-network (DN) PEG–alginate cryogel. The PEG network is formed by a Michael addition reaction between thiol-based crosslinker and 8-arm PEG-acrylate. The second network is covalently crosslinked through EDC/NHS-mediated coupling of carboxyl groups in alginate and adipic acid dihydrazide (AAD). The subsequent freezing and gelation of the gel precursor at sub-zero temperatures results in an ice templated cryogel with an interconnected macroporous network. These cryogels demonstrate high elasticity, compressive modulus and rapid swelling equilibrium in aqueous environments, as well as controlled degradation under physiological conditions. Compared to the classical Ca²⁺ ion crosslinking systems, the covalent linking of the alginate in the double-network cryogel shows advantages in mechanical and structural stability. In addition, it is cell-compatible and allows culture of mesenchymal stem cells (MSCs) with homogeneous infiltration. Furthermore, the double-network cryogels supports chondrogenic differentiation of MSCs upon treatment with chondrogenic media or macrophage-conditioned media for a short period of time. These results indicate that crosslinking chemistry and polymer composition can be used to modulate the balance between mechanical performance and degradation behavior, while maintaining cytocompatibility and an interconnected macroporous network, thereby providing a scaffold design strategy for applications that require coordinated mechanical support and mass transfer, such as cartilage-related tissue engineering. Full article

Sports injuries, especially musculoskeletal and neurological types from strenuous exercise, are a global public health challenge. Characterized by a high incidence and slow recovery, these injuries differ from typical trauma, often resulting in severe mechanical transmission loss and an imbalanced immune microenvironment. Consequently, standard interventions struggle to achieve true tissue regeneration. Gelatin, a collagen-derived biomaterial, offers RGD-mediated cell adhesion, MMP-responsive degradation, and high modifiability. These qualities make it an excellent foundation for biomimetic repair scaffolds. This paper reviews the design principles and recent advances in gelatin-based multifunctional hydrogels in sports medicine. First, we analyse their structure and engineering advantages. Next, we summarise strategies and mechanisms for modules like conductivity, antibacterial activity, self-healing, stimulus responsiveness, and tissue adhesion. The review links these modules to types of injuries: bone or cartilage, tendon or ligament, skeletal muscle, spinal cord, and peripheral nerve. It clarifies their clinical and translational value in remodelling immune microenvironments, regulating electrophysiology, promoting interfacial regeneration, and restoring motor function. This review provides focused insights from materials science and sports rehabilitation to advance precision treatments for sports injuries. Full article

Articular cartilage is characterized by its avascular, aneural, and alymphatic nature, which confers a limited intrinsic capacity for self-repair. Current regenerative strategies primarily focus on alleviating pain, mitigating symptoms, and restoring joint function. However, their long-term efficacy remains uncertain. Cartilage tissue engineering has emerged as a promising alternative to conventional therapies, offering innovative solutions for articular cartilage regeneration. Central to this approach is the development of functional biomaterials capable of supporting chondrogenic cell adhesion, proliferation, and differentiation, thereby facilitating effective cartilage repair. In this study, we introduce a novel protein-based recombinant spider silk (RSS) as a potential biomaterial for modulating chondrocyte behavior and enabling engineered cartilage formation both in vitro and in vivo. RSS was generated through molecular cloning and processed into silk fibers using biomimetic spinning and acidic coagulation techniques. In micromass cultures of murine chondrocytes, RSS significantly promoted cell aggregation, resulting in increased cell density. Alcian blue and Oil Red O staining demonstrated that RSS-treated cultures produced abundant glycosaminoglycans, a hallmark of chondrogenic activity, while exhibiting minimal lipid accumulation. These findings suggest that RSS supports chondrogenic differentiation and suppresses adipogenic lineage commitment. Real-time PCR analysis revealed upregulation of the chondrogenesis-related gene Sox9 and downregulation of the adipogenic marker PPARγ and the hypertrophic marker Runx2 in RSS-treated micromass cultures. RNA sequencing further corroborated these observations, underscoring the role of RSS in modulating extracellular matrix (ECM) remodeling in chondrocytes. In a subcutaneous transplantation model using severe combined immunodeficiency (SCID) mice, chondrocytes encapsulated in three-dimensional hydrogel scaffolds containing RSS exhibited significantly enhanced ECM accumulation compared to RSS-free controls, indicating that RSS supports the maintenance of the chondrocyte phenotype and promotes cartilage formation in vivo, and underscoring its promising potential as a component of hydrogel composite systems. These findings highlight the potential of RSS as a functional biomaterial to preserve chondrocyte functionality and advance engineered cartilage formation, presenting a promising avenue for cartilage tissue engineering and regeneration. Full article

The advancement of modern regenerative medicine is closely associated with additive technologies that enable the creation of tissue-engineered constructs and personalized bioprostheses. Three-dimensional bioprinting allows precise modeling of tissue architecture and extracellular matrix microstructures. Recent studies demonstrate rapid growth in the use of 3D bioprinting for biomedical applications including regenerative medicine, pharmaceutical research, and biotechnology. Special attention is given to the development of bioinks that combine biological and structural functions and maintain cell viability during printing. Modern technologies allow the fabrication of skin, bone, vascular, and cartilage tissues with high structural accuracy. The technology is also actively used in reconstructive surgery for the production of personalized implants. However, challenges remain related to vascularization, standardization of materials, and ethical aspects of clinical use. This review summarizes the main principles of 3D bioprinting, technological approaches, biomedical applications, and future perspectives of additive technologies in regenerative medicine. Full article

Hyaluronic acid (HA), a native non-sulfated glycosaminoglycan of the extracellular matrix, has emerged as a central biomaterial in tissue engineering due to its biocompatibility, hydration capacity, and receptor-mediated bioactivity. Beyond its structural role, HA actively regulates cellular behaviors through interactions with receptors such as CD44 and RHAMM, with outcomes highly dependent on molecular weight, degradation state, and matrix context. Recent advances in chemical modification and crosslinking strategies have enabled the development of HA-based hydrogels, nanofibers, and composite systems with tunable mechanics and degradation profiles, supporting applications in bone, cartilage, vascular, and skin regeneration, as well as in emerging platforms such as 3D bioprinting and nanomedicine. However, inconsistent biological responses and limited clinical translation remain key challenges. This review integrates current understanding of HA synthesis, physicochemical properties, degradation, and receptor-mediated signaling, and establishes a mechanistic framework linking molecular characteristics, matrix mechanics, and cell responses. Building on this framework, we outline design strategies for multifunctional HA composites, advanced biofabrication approaches, and receptor-targeted systems, providing a basis for the rational engineering of next-generation HA-based biomaterials with improved translational potential. Full article

Hydrogel scaffolds have emerged as a central platform in tissue engineering due to their ability to mimic the extracellular matrix and support cellular functions. Among natural polymers, chitin and its derivative chitosan have emerged as valuable candidates for hydrogel scaffold development because of their biodegradability, compatibility with living tissues, and inherent biological functionality; however, their distinct and complementary roles in hydrogel scaffold design are often insufficiently differentiated in the literature. This review provides a comprehensive and mechanism-driven analysis of chitin- and chitosan-based hydrogel scaffolds, emphasising how their molecular structure governs network formation, mechanical performance, and biological functionality. Chitin is highlighted primarily as a structurally robust and crystalline component suitable for reinforcement. In contrast, chitosan serves as a versatile, soluble, and chemically reactive matrix enabling various crosslinking and functionalization strategies. Recent advances in physical, ionic, and covalent crosslinking as well as composite scaffold engineering, biofunctionalization, and emerging fabrication approaches such as injectable systems and three-dimensional bioprinting are systematically examined. The relationships between scaffold architecture, degradation behaviour, and cellular responses are discussed in key tissue engineering applications, including bone, cartilage, skin, and nerve regeneration. Importantly, this review introduces a unified structure–property–function framework that distinguishes the roles of chitin and chitosan within hydrogel systems and links crosslinking mechanisms to application-specific performance requirements, an aspect not comprehensively addressed in previous studies. Current challenges related to mechanical limitations, material variability, and clinical translation are critically evaluated, and future perspectives for the rational design of next-generation biomimetic hydrogel scaffolds are proposed. Full article

Most high-tech drugs and tissue engineering products based on human chondrocytes currently available on the market are aimed at restoring traumatic damage to cartilage tissue. However, in the presence of inflammation, their regenerative potential is significantly reduced, which limits their use in patients with osteoarthritis—one of the most common degenerative and inflammatory joint pathologies. The central element of the pathogenesis of osteoarthritis is inflammation—not classical acute inflammation, but rather chronic low-grade inflammation, primarily mediated by mechanisms of the innate immune response. Therefore, a key challenge is to enhance the anti-inflammatory effectiveness of cell-based drugs to broaden their indications to include degenerative diseases such as osteoarthritis and arthrosis. In recent years, cell-based drugs using stem cells, including mesenchymal stem cells (MSCs), hematopoietic stem cells (HSCs), and stromal vascular fraction (SVF) cells, have been actively studied. Despite their confirmed safety in inflammatory processes, meta-analyses of clinical trials show limited effectiveness in improving symptoms and MRI data in the treatment of osteoarthritis. A promising direction appears to be the development of combined cell-based drugs that combine MSCs with M2-polarized macrophages; however, data on their clinical effectiveness are still insufficient. This review explores key cellular effectors of inflammation and its molecular mechanisms, potential strategies for creating tissue engineering products that possess not only regenerative but also pronounced anti-inflammatory effects. The development of such products will expand their application in the treatment of inflammatory-degenerative joint diseases. Full article

The limited regenerative capacity of articular cartilage (AC) following injury has led to a high prevalence of degenerative AC-related disorders, including osteoarthritis (OA). Current clinical treatments for OA have failed to halt disease progression, driving growing interest in cartilage tissue engineering (CTE) strategies aimed at developing biomimetic substitutes to regenerate damaged AC tissue. Among the available biofabrication techniques, electrospinning has gained attention due to its ability to generate fibrous scaffolds that closely mimic the architecture of the native AC extracellular matrix, while also serving as versatile drug delivery platforms with high surface area and elevated drug loading efficiency. Small molecules, low-molecular-weight therapeutic agents capable of interacting with both cell membrane and intracellular components, can be incorporated into these scaffold systems to target the underlying mechanisms of OA. This review examines the current state of the art of small molecule-loaded electrospun scaffolds for CTE applications. Small molecules targeting pain, inflammation, and cartilage function restoration show considerable therapeutic potential, and their incorporation into coaxial and other advanced electrospinning setups enables controlled and sustained drug release. Recent examples of small molecule-loaded electrospun scaffolds for AC repair demonstrate enhanced chondrogenic differentiation and neo-cartilage formation, supporting their potential as viable CTE strategies. Nevertheless, challenges related to drug release kinetics, scaffold load-bearing properties, manufacturing scalability, reproducibility, and regulatory approval remain critical barriers to clinical translation. Emerging fabrication strategies, AI-assisted optimization, personalized medicine approaches, and stimuli-responsive drug delivery systems offer promising avenues to overcome these limitations and advance the clinical adoption of these platforms. Full article

Solution electrospinning (SES) and melt electrowriting (MEW) are complementary fiber-based fabrication platforms extensively investigated in tissue engineering. SES generates fibers typically ranging from the nanometer to the low-micrometer scale, producing fibrous networks that mimic the native extracellular matrix (ECM) and support key cellular functions. MEW, by contrast, operates solvent-free and enables precise, layer-by-layer deposition of microfibers with well-controlled geometry, conferring the mechanical integrity and open-pore architecture that SES constructs inherently lack. Despite growing interest, the body of peer-reviewed literature reporting original hybrid SES–MEW fabrication and biological outcome data remains limited, with no comprehensive cross-tissue synthesis available to date. This narrative review examines the current state of SES–MEW hybrid strategies across five tissue engineering targets selected for their clinical relevance: skin, vascular grafts, bone, cartilage, cardiac valves, and skeletal muscle. For each application, the architectural rationale, the fabrication approach, and the in vitro and in vivo biological outcomes are discussed in an integrated manner, with attention to how the spatial organization of nano- and microfibers translates into tissue-specific functional responses. A comparative analysis across tissue types highlights both the versatility of hybrid constructs and their persistent limitations, including suture retention values that remain below clinically accepted thresholds in vascular applications, incomplete cellular infiltration through dense nanofibrous layers, and the absence of validated, reproducible scale-up protocols compatible with clinical-grade manufacturing. The review concludes by identifying the most critical open questions in the field, encompassing process standardization, regulatory classification, and the emerging role of machine learning in closed-loop MEW process optimization. This work aims to provide an evidence-based perspective on the current state of hybrid SES–MEW scaffold engineering and the key translational gaps limiting clinical application. Full article

Articular cartilage has a limited capacity for self-repair, and effective strategies for its regeneration remain a major clinical challenge. Full-thickness cartilage defects extending to the subchondral bone induce an enhanced inflammatory response and impair spontaneous healing. This study aimed to evaluate the regenerative potential of autologous chondrocyte transplantation using an insoluble polyethersulfone (PES) scaffold in a rabbit model of grade III articular cartilage lesions. Chondrocytes were isolated and expanded in vitro and subsequently seeded onto PES membranes. Sixty-two rabbit knees with defects extending to the subchondral bone were divided into three groups: group I received chondrocyte-seeded PES scaffolds (n = 25), group II received cell-free PES scaffolds (n = 25), and group III served as an untreated control (n = 12). Cartilage regeneration was evaluated macroscopically and histologically over 52 weeks. In addition, the chondrogenic differentiation potential of cells cultured on PES scaffolds was assessed. This study extends our previous investigations of PES scaffolds in grade IV cartilage defects to a clinically relevant grade III lesion model, enabling evaluation of regenerative outcomes at an earlier stage of cartilage degeneration. The results demonstrated superior tissue regeneration in defects treated with chondrocyte-seeded PES scaffolds compared to both control groups. These findings indicate that synthetic PES scaffolds support cartilage repair and represent a promising biomaterial for the development of cell-based therapies in articular cartilage regeneration. Full article

Tissue engineering integrates concepts from medicine, biology, and engineering to create living constructs capable of repairing, replacing, or supporting damaged tissues. This multidisciplinary field relies on the interplay between biomaterials, cellular sources, and bioactive signaling to achieve functional tissue regeneration. This review provides a comprehensive overview of recent advances in scaffold design, highlighting natural, synthetic, and hybrid materials, as well as innovative fabrication techniques such as electrospinning, 3D bioprinting, and smart biomaterials. It discusses the role of stem cells and growth factors in directing regeneration and examines a wide range of clinical applications, including skin regeneration, cartilage repair, bone tissue engineering, dental and periodontal regeneration, nerve repair, cardiac tissue engineering, liver tissue models, and ophthalmic applications. Current challenges, such as immune responses, limited vascularization, scalability, and regulatory barriers, are addressed alongside emerging strategies aimed at improving clinical translation. By integrating diverse tissue types and engineering approaches within a unified framework, this review offers a broad yet detailed perspective on the current state and future directions of regenerative medicine. Full article

Collagen, the most abundant extracellular matrix (ECM) protein, has emerged as a cornerstone biomaterial in drug delivery and regenerative medicine due to its intrinsic biocompatibility, biodegradability, and low immunogenicity. Engineering collagen into microspheres transforms its functionality beyond bulk scaffolds by increasing surface area, enabling minimally invasive delivery, and providing precise control over degradation, mechanical properties, and therapeutic release. This review provides a comprehensive analysis of collagen-based microspheres, with a particular focus on their dual role as biomimetic microenvironments and delivery systems. Recent advances in fabrication strategies, including emulsification, microfluidics, spray-drying, and electrospraying, are discussed in the context of scalability, size control, and payload encapsulation. Composite approaches that incorporate bioactive minerals, polysaccharides, or synthetic polymers are highlighted for their ability to enhance mechanical performance and biological function. We further examine characterization frameworks that link microscale structure and physicochemical properties to biological outcomes, with emphasis on how collagen microspheres replicate key structural, mechanical, and signaling features of native tissue microenvironments. Collagen microspheres have demonstrated broad utility as controlled delivery platforms, cell-instructive microcarriers, and injectable systems for tissue regeneration, including applications in bone, cartilage, skin, and nerve repair, as well as advanced wound care and localized cancer therapy. Finally, we critically assess current challenges related to scalable manufacturing, sterilization compatibility, and batch reproducibility, and outline emerging solutions such as recombinant collagen, advanced biofabrication, and stimuli-responsive systems. Collectively, collagen microspheres represent a powerful and adaptable platform poised to advance next-generation regenerative and therapeutic technologies. Full article

Piezoelectric biomaterials have attracted considerable interest in osteochondral tissue engineering owing to their inherent ability to produce electrical signals in response to mechanical stimuli without external power, thereby closely mimicking the physiological electrical microenvironment required for tissue regeneration. This review comprehensively summarizes recent insights into biological piezoelectricity from the molecular to the macroscopic level, highlighting its interplay with streaming potentials and its regulatory roles in bone and cartilage regeneration. We critically analyze recent advances in major piezoelectric material systems, including ceramics, polymers, and composite scaffolds, with emphasis on their structural characteristics, bioactive performance, and suitability for tissue-specific repair. Among them, polymer-based composite and hybrid piezoelectric scaffolds appear particularly promising for the development of flexible, high-performance osteochondral repair platforms, as they offer a more favorable balance between mechanical compliance, electromechanical output, and biological adaptability. Despite encouraging preclinical findings, significant challenges remain, including biocompatibility, controlled degradation kinetics, and the precise modulation of electrical cues for specific biological contexts. To address these barriers, future research should focus on optimizing scaffold design, integrating responsive and multimodal stimulation strategies, and establishing standardized protocols for preclinical evaluation and clinical translation. Overall, piezoelectric biomaterials hold substantial potential for the development of innovative regenerative therapies for complex osteochondral defects. Full article