Cartilage Tissue Engineering Research Articles

Temporal modulation of inflammation and chondrogenesis through dendritic nanoparticle-mediated therapy with diclofenac surface modification and strontium ion encapsulation

Cartilage tissue engineering holds great promise for efficient cartilage regeneration. However, early inflammatory reactions to seed cells and/or scaffolds impede this process. Consequently, managing inflammation is of paramount importance. Moreover, due to the body’s restricted chondrogenic capacity, inducing cartilage regeneration becomes imperative. Thus, a controlled platform is essential to establish an anti-inflammatory microenvironment before initiating the cartilage regeneration process. In this study, we utilized fifth-generation polyamidoamine dendrimers (G5) as a vehicle for drugs to create composite nanoparticles known as G5-Dic/Sr. These nanoparticles were generated by surface modification with diclofenac (Dic), known for its potent anti-inflammatory effects, and encapsulating strontium (Sr), which effectively induces chondrogenesis, within the core. Our findings indicated that the G5-Dic/Sr nanoparticle exhibited selective Dic release during the initial 9 days and gradual Sr release from days 3 to 15. Subsequently, these nanoparticles were incorporated into a gelatin methacryloyl (GelMA) hydrogel, resulting in GelMA@G5-Dic/Sr. In vitro assessments demonstrated GelMA@G5-Dic/Sr’s biocompatibility with bone marrow stem cells (BMSCs). The enclosed nanoparticles effectively mitigated inflammation in lipopolysaccharide-induced RAW264.7 macrophages and significantly augmented chondrogenesis in BMSCs cocultures. Implanting BMSCs-loaded GelMA@G5-Dic/Sr hydrogels in immunocompetent rabbits for 2 and 6 weeks revealed diminished inflammation and enhanced cartilage formation compared to GelMA, GelMA@G5, GelMA@G5-Dic, and GelMA@G5/Sr hydrogels. Collectively, this study introduces an innovative strategy to advance cartilage regeneration by temporally modulating inflammation and chondrogenesis in immunocompetent animals. Through the development of a platform addressing the temporal modulation of inflammation and the limited chondrogenic capacity, we offer valuable insights to the field of cartilage tissue engineering.

Evaluation of the effects of decellularized umbilical cord Wharton's Jelly ECM on polyhydroxy butyrate electrospun scaffolds: A new strategy for cartilage tissue engineering

The field of regenerative medicine has recently witnessed the emergence of the allogeneic decellularized extracellular matrix as a scaffold with natural biological signals in tissue engineering. In the present study, to prevent immune rejection and disease transmission, Wharton's Jelly extracellular matrix (WJM) derived from the human umbilical cord was first decellularized (DWJM). Eventually, the fibrous scaffolds based on poly 3-hydroxybutyrate (PHB) and five different concentrations (0, 1, 3, 5, and 10 wt%) of DWJM were fabricated through electrospinning. The results demonstrate reducing the diameter of the fibers, improved mechanical properties, hydrophilicity, and degradation rate in the scaffold containing 3 wt % DWJM. Excellent biocompatibility and increased chondrocyte cell adherence rate on the substrate of PHB-DWJM 3 % scaffolds compared with pure PHB scaffolds can be attributed to the high amounts of Collagen, sulfated glycosaminoglycans (GAGs), and hyaluronic acid (HA) in the DWJM. In conclusion, the physicochemical properties and biological activities of PHB-DWJM scaffolds indicate that blending DWJM with PHB electrospun scaffold can provide a suitable environment for articular cartilage tissue regeneration.

Tailorable acrylate-endcapped urethane-based polymers for precision in digital light processing: Versatile solutions for biomedical applications

Bioengineering seeks to replicate biological tissues exploiting scaffolds often based on polymeric biomaterials. Digital light processing (DLP) has emerged as a potent technique to fabricate tissue engineering (TE) scaffolds. However, the scarcity of suitable biomaterials with desired physico-chemical properties along with processing capabilities limits DLP's potential. Herein, we introduce acrylate-endcapped urethane-based polymers (AUPs) for precise physico-chemical tuning while ensuring optimal computer-aided design/computer-aided manufacturing (CAD/CAM) mimicry. Varying the polymer backbone (i.e. poly(ethylene glycol) (PEG) versus poly(propylene glycol) (PPG)) and photo-crosslinkable endcap (i.e. di-acrylate versus hexa-acrylate), we synthesized a series of photo-crosslinkable materials labeled as UPEG2, UPEG6, UPPG2 and UPPG6. Comprehensive material characterization including physico-chemical and biological evaluations, was followed by a DLP processing parametric study for each material. The impact of the number of acrylate groups per polymer (2 to 6) on the physico-chemical properties was pronounced, as reflected by a reduced swelling, lower water contact angles, accelerated crosslinking kinetics, and increased Young's moduli upon increasing the acrylate content. Furthermore, the different polymer backbones also exerted a substantial effect on the properties, including the absence of crystallinity, remarkably reduced swelling behaviors, a slight reduction in Young's modulus, and slower crosslinking kinetics for UPPG vs UPEG. The mechanical characteristics of DLP-printed samples showcased the ability to tailor the materials' stiffness (ranging from 0.4 to 5.3 MPa) by varying endcap chemistry and/or backbone. The in vitro cell assays confirmed biocompatibility of the material as such and the DLP-printed discs. Furthermore, the structural integrity of 3D scaffolds was preserved both in dry and swollen state. By adjusting the backbone chemistry or acrylate content, the post-swelling dimensions could be customized towards the targeted application. This study showcases the potential of these materials offering tailorable properties to serve many biomedical applications such as cartilage TE.

Neuro-Immunomodulatory Potential of Nanoenabled 4D Bioprinted Microtissue for Cartilage Tissue Engineering.

Cartilage defects trigger post-traumatic inflammation, leading to a catabolic metabolism in chondrocytes and exacerbating cartilage degradation. Current treatments aim to relieve pain but fail to target the inflammatory process underlying osteoarthritis (OA)progression. Here, a human cartilage microtissue (HCM) nanoenabled with ibuprofen-loaded poly(lactic-co-glycolic acid) nanoparticles (ibu-PLGA NPs) is 4D-bioprinted to locally mitigate inflammation and impair nerve sprouting. Under an in vitro inflamed environment, the nanoenabled HCM exhibits chondroprotective potential by decreasing the interleukin (IL)1β and IL6 release, while sustaining extracellular matrix (ECM) production. In vivo, assessments utilizing the air pouch mouse model affirm the nanoenabled HCM non-immunogenicity. Nanoenabled HCM-derived secretomes do not elicit a systemic immune response and decrease locally the recruitment of mature dendritic cells and the secretion of multiple inflammatory mediators and matrix metalloproteinases when compared to inflamed HCM condition. Notably, the nanoenabled HCM secretome has no impact on the innervation profile of the skin above the pouch cavity, suggesting a potential to impede nerve growth. Overall, HCM nanoenabled with ibu-PLGA NPs emerges as a potent strategy to mitigate inflammation and protect ECM without triggering nerve growth, introducing an innovative and promising approach in the cartilage tissue engineering field.

Advanced polymer composites and polymer hybrids for cartilage tissue engineering

AbstractThe repair and regeneration of cartilage is a challenge for scientists and clinical surgery. Achieving cell adhesion and regeneration, anti‐inflammatory, lubrication, targeted drug delivery and controlled release simultaneously in cartilage treatment are the goals of researchers. Polymer composites and hybrids have the potential to realize above functions in cartilage tissue engineering. This review refers to cartilage injuries, current clinical techniques, and their benefits and limitations, focusing on the most relevant and state of art of advanced polymers for cartilage tissue engineering. The frontier applications of multifunctional polymer composites and hybrids in cartilage tissue engineering are discussed in depth, including polymer scaffold, polymer bio‐lubricant, and zwitterionic polymer for drug delivery and sustained drug release. A summary of comprehensive properties of polymers such as processability, mechanical properties, biocompatibility, biodegradability, hydrophilicity, cytotoxicity, etc., and their mechanisms are analyzed. Furthermore, some key challenges and outstanding concerns on polymer‐based materials for cartilage tissue engineering are presented followed by future perspectives.Highlights The state of art of advanced polymers for cartilage tissue engineering. The advanced bionic property and mechanism of polymer composites and hybrids. Polymers for scaffold, biolubricant, drug delivery, sustained drug release. Future perspectives on polymer composites, hybrids‐based cartilage materials.

Preparation of kartogenin-loaded PLGA microspheres and a study of their drug release profiles

Introduction: Kartogenin, a potent inducer of chondrogenic differentiation in mesenchymal stem cells and a key agent in cartilage regeneration, presents a viable therapeutic strategy for osteoarthritis management. Despite the abundance of literature on therapeutic potential of kartogenin, there is a paucity of studies characterizing the formulation specifics in microsphere fabrication. This exploration is pivotal to advances in regenerative medicine, particularly in the domain of cartilage regeneration, to assure clinical efficacy and safety.Methods: In this work, we fabricated kartogenin-loaded PLGA microspheres with diverse formulations and their particle size, size distribution, encapsulation efficiency, drug loading and release profiles were characterized. Ratio of polymer, drug, and solvent and the use of surfactant was used as variables, and in particular, the effect of surfactant on particles was investigated.Results: The average diameter of the spheres was 16.0–31.7 μm. Morphological variations from solid to porous surface structures depending on surfactant incorporation during the emulsification process was observed. Cumulative kartogenin release from microspheres ranged from 53.8% to 80.9% on day 28, and release profiles conform predominantly to the Korsmeyer-Peppas kinetics model.Discussion: This study provides a foundational framework for modulating kartogenin release dynamics, a critical consideration for optimizing therapeutic efficacy and minimizing adverse effects in cartilage tissue engineering applications.

A Review of Cartilage Defect Treatments Using Chitosan Hydrogels in Experimental Animal Models.

Chitosan (CS) is a polycationic polysaccharide comprising glucosamine and N-acetylglucosamine and constitutes a potential material for use in cartilage tissue engineering. Moreover, CS hydrogels are able to promote the expression of cartilage matrix components and reduce inflammatory and catabolic mediator production by chondrocytes. Although all the positive outcomes, no review has analyzed the effects of CS hydrogels on cartilage repair in animal models. This study aimed to review the literature to examine the effects of CS hydrogels on cartilage repair in experimental animal models. The search was done by the descriptors of the Medical Subject Headings (MeSH) defined below: "Chitosan," "hydrogel," "cartilage repair," and "in vivo." A total of 420 articles were retrieved from the databases Pubmed, Scopus, Embase, Lilacs, and Web of Science. After the eligibility analyses, this review reported 9 different papers from the beginning of 2002 through the middle of 2022. It was found that cartilage repair was improved with the treatment of CS hydrogel, especially the one enriched with cells. In addition, CS hydrogel produced an upregulation of genes and proteins that act in the cartilage repair process, improving the biomechanical properties of gait.. In conclusion, CS hydrogels were able to stimulate tissue ingrowth and accelerate the process of cartilage repair in animal studies.

Double crosslinked hyaluronic acid and collagen as a potential bioink for cartilage tissue engineering

The avascular nature of hyaline cartilage results in limited spontaneous self-repair and regenerative capabilities when damaged. Recent advances in three-dimensional bioprinting have enabled the precise dispensing of cell-laden biomaterials, commonly referred to as ‘bioinks’, which are emerging as promising solutions for tissue regeneration. An effective bioink for cartilage tissue engineering needs to create a micro-environment that promotes cell differentiation and supports neocartilage tissue formation. In this study, we introduced an innovative bioink composed of photocurable acrylated type I collagen (COLMA), thiol-modified hyaluronic acid (THA), and poly(ethylene glycol) diacrylate (PEGDA) for 3D bioprinting cartilage grafts using human nasal chondrocytes. Both collagen and hyaluronic acid, being key components of the extracellular matrix (ECM) in the human body, provide essential biological cues for tissue regeneration. We evaluated three formulations – COLMA, COLMA+THA, and COLMA+THA+PEGDA – for their printability, cell viability, structural integrity, and capabilities in forming cartilage-like ECM. The addition of THA and PEGDA significantly enhanced these properties, showcasing the potential of this bioink in advancing applications in cartilage repair and reconstructive surgery.

Tuning the rheological properties of chitosan/alginate hydrogels for tissue engineering application

Biomaterials that mimic biological tissues are in great demand in tissue engineering. Hydrogels are rising as a conducive candidate in tissue engineering on account of their water-holding capacity, mechanical strength, and elasticity. Nevertheless, the development of hydrogels that mimic biological tissues with the desired stability and mechanical strength, remains a notable barrier. In this investigation, chitosan/alginate hydrogels were prepared by tuning the chitosan concentration from 0.5 % to 2.5 %w/v with a fixed 1 %w/v alginate concentration using 0.1 % glutaraldehyde as a gelling agent. The hydrogel system forms through covalent bonding between chitosan and alginate, mediated by aldehyde groups of the glutaraldehyde. The mechanical strength of the hydrogel was elucidated by probing its viscoelastic behavior through rheological analysis. The rheological investigations revealed that the prepared chitosan/alginate hydrogels are profoundly stable with shear-thinning characteristics. The increase in chitosan concentration enhanced the stability and viscoelastic attributes of the hydrogels. The yield stress values ranging from 0.93 kPa to 14.24 kPa indicate the possibility of using these hydrogels in bioadhesives and soft and bone tissue engineering. The complex modulus of the prepared chitosan/alginate hydrogels resembles the shear modulus of liver tissues, osteogenic cells, and articular cartilage, and hence, these hydrogels pose as suitable candidates in liver, bone, and cartilage tissue engineering. The chitosan/alginate hydrogels possess outstanding self-healing ability, along with biocompatibility, stability, and mechanical strength, rendering them highly advantageous for applications in biomedical tissue engineering and bioadhesives.

Biofabrication of Tissue-Engineered Cartilage Constructs Through Faraday Wave Bioassembly of Cell-Laden Gelatin Microcarriers.

Acoustic biofabrication is an emerging strategy in tissue engineering due to its mild and fast manufacturing process. Herein, tissue-engineered cartilage constructs with high cell viability are fabricated from cell-laden gelatin microcarriers (GMs) through Faraday wave bioassembly, a typical acoustic "bottom-up" manufacturing process. Assembly modules are first prepared by incorporating cartilage precursor cells, the chondrogenic cell line ATDC5, or bone marrow-derived mesenchymal stem cells (BMSCs), into GMs. Patterned structures are formed by Faraday wave bioassembly of the cell-laden GMs. Due to the gentle and efficient assembly process and the protective effects of microcarriers, cells in the patterned structures maintain high activity. Subsequently, tissue-engineered cartilage constructs are obtained by inducing cell differentiation of the patterned structures. Comprehensive evaluations are conducted to verify chondrocyte differentiation and the formation of cartilage tissue constructs in terms of cell viability, morphological analysis, gene expression, and matrix production. Finally, implantation studies with a rat cartilage defect model demonstrate that these tissue-engineered cartilage constructs are beneficial for the repair of articular cartilage damage in vivo. This study provides the first biofabrication of cartilage tissue constructs using Faraday wave bioassembly, extending its application to engineering tissues with a low cell density.

Simultaneous usage of sulforaphane nanoemulsion and tannic acid in ternary chitosan/gelatin/PEG hydrogel for knee cartilage tissue engineering: In vitro and in vivo study

The therapeutic potential of tissue engineering in addressing articular cartilage defects has been a focal point of research for numerous years. Despite its promising outlook, a persistent challenge within this domain is the lack of sufficient functional integration between engineered and natural tissues. This study introduces a novel approach that employs a combination of sulforaphane (SFN) nanoemulsion and tannic acid to enhance cartilage tissue engineering and promote tissue integration in a rat knee cartilage defect model. To substantiate our hypothesis, we conducted a series of in vitro and in vivo experiments. The SFN nanoemulsion was characterized using DLS, zeta potential, and TEM analyses. Subsequently, it was incorporated into a ternary polymer hydrogel composed of chitosan, gelatin, and polyethylene glycol. We evaluated the hydrogel with (H-SFN) and without (H) the SFN nanoemulsion through a comprehensive set of physicochemical, mechanical, and biological analyses. For the in vivo study, nine male Wistar rats were divided into three groups: no implant (Ctrl), H, and H-SFN. After inducing a cartilage defect, the affected area was treated with tannic acid and subsequently implanted with the hydrogels. Four weeks post-implantation, the harvested cartilage underwent histological examination employing H&E, safranin O/fast green, alcian blue, and immunohistochemistry staining techniques. Our results revealed that the SFN nanodroplets had an average diameter of 75 nm and a surface charge of −11.58 mV. Moreover, degradation, swelling rates, hydrophilicity, and elasticity features of the hydrogel incorporating SFN were improved. Histopathological analysis indicated a higher production of GAGs and collagen in the H-SFN group. Furthermore, the H-SFN group exhibited superior cartilage regeneration and tissue integration compared to the Ctrl and H groups. In conclusion, the findings of this study suggest the importance of considering cell protective properties in the fabrication of scaffolds for knee cartilage defects, emphasizing the potential significance of the proposed SFN nanoemulsion and tannic acid approach in advancing the field of cartilage tissue engineering.

Cartilage tissue engineering using decellularized biomatrix hydrogel containing TGF-β-loaded alginate microspheres in mechanically loaded bioreactor

Physiochemical tissue inducers and mechanical stimulation are both efficient variables in cartilage tissue fabrication and regeneration. In the presence of biomolecules, decellularized extracellular matrix (ECM) may trigger and enhance stem cell proliferation and differentiation. Here, we investigated the controlled release of transforming growth factor beta (TGF-β1) as an active mediator of mesenchymal stromal cells (MSCs) in a biocompatible scaffold and mechanical stimulation for cartilage tissue engineering. ECM-derived hydrogel with TGF-β1-loaded alginate-based microspheres (MSs) was created to promote human MSC chondrogenic development. Ex vivo explants and a complicated multiaxial loading bioreactor replicated the physiological conditions. Hydrogels with/without MSs and TGF-β1 were highly cytocompatible. MSCs in ECM-derived hydrogel containing TGF-β1/MSs showed comparable chondrogenic gene expression levels as those hydrogels with TGF-β1 added in culture media or those without TGF-β1. However, constructs with TGF-β1 directly added within the hydrogel had inferior properties under unloaded conditions. The ECM-derived hydrogel group including TGF-β1/MSs under loading circumstances formed better cartilage matrix in an ex vivo osteochondral defect than control settings. This study demonstrates that controlled local delivery of TGF-β1 using MSs and mechanical loading is essential for neocartilage formation by MSCs and that further optimization is needed to prevent MSC differentiation towards hypertrophy.

Adipose-derived mesenchymal stem cell-incorporated PLLA porous microspheres for cartilage regeneration.

In facial plastic surgery, patients with nasal deformity are often treated by rib cartilage transplantation. In recent years, cartilage tissue engineering has developed as an alternative to complex surgery for patients with minor nasal defects via injection of nasal filler material. In this study, we prepared an injectable nasal filler material containing poly-L-lactic acid (PLLA) porous microspheres (PMs), hyaluronic acid (HA) and adipose-derived mesenchymal stem cells (ADMSCs). We seeded ADMSCs into as-prepared PLLA PMs using our newly invented centrifugation perfusion technique. Then, HA was mixed with ADMSC-incorporated PLLA PMs to form a hydrophilic and injectable cell delivery system (ADMSC-incorporated PMH). We evaluated the biocompatibility of PMH invitro and invivo. PMH has good injectability and provides a favorable environment for the proliferation and chondrogenic differentiation of ADMSCs. Invivo experiments, we observed that PMH has good biocompatibility and cartilage regeneration ability. In this study, a injectable cell delivery system was successfully constructed. We believe that PMH has potential application in cartilage tissue engineering, especially in nasal cartilage regeneration.

Electrical Stimulation of Mesenchymal Stem Cells as a Tool for Proliferation and Differentiation in Cartilage Tissue Engineering: A Scaffold-Based Approach.

Electrical stimulation (ES) is a widely discussed topic in the field of cartilage tissue engineering due to its ability to induce chondrogenic differentiation (CD) and proliferation. It shows promise as a potential therapy for osteoarthritis (OA). In this study, we stimulated mesenchymal stem cells (MSCs) incorporated into collagen hydrogel (CH) scaffolds, consisting of approximately 500,000 cells each, for 1 h per day using a 2.5 Vpp (119 mV/mm) 8 Hz sinusoidal signal. We compared the cell count, morphology, and CD on days 4, 7, and 10. The results indicate proliferation, with an increase ranging from 1.86 to 9.5-fold, particularly on day 7. Additionally, signs of CD were observed. The stimulated cells had a higher volume, while the stimulated scaffolds showed shrinkage. In the ES groups, up-regulation of collagen type 2 and aggrecan was found. In contrast, SOX9 was up-regulated in the control group, and MMP13 showed a strong up-regulation, indicating cell stress. In addition to lower stress levels, the control groups also showed a more spheroidic shape. Overall, scaffold-based ES has the potential to achieve multiple outcomes. However, finding the appropriate stimulation pattern is crucial for achieving successful chondrogenesis.

Enhancing 3D poly[ɛ]caprolactone scaffold properties through alkaline hydrolysis for improved chondrocyte culture: Morphological, physicochemical, and biocompatibility evaluations

This study investigates the impact of alkaline hydrolysis on the morphology, physicochemical properties, and mechanical strength of poly[ε]caprolactone (PCL) scaffolds fabricated using a melt-based electrohydrodynamic process. We systematically analyzed how a brief, 5-min alkaline hydrolysis treatment influenced scaffold characteristics compared to longer durations (15 and 30 min). Results demonstrated that the short-duration treatment significantly increased fiber diameter and reduced pore size while modifying the scaffold's surface chemistry. Importantly, the 5-min treatment optimized the water contact angle to 55–65°, enhancing hydrophilicity which facilitated superior cell attachment and proliferation of the C28/I2 immortalized human chondrocyte cell line. Mechanical testing revealed that while alkaline hydrolysis decreased the scaffold's Young's modulus, a 5-min treatment maintained sufficient mechanical integrity for potential tissue engineering applications, in contrast to the more substantial degradation observed with longer treatments.Biocompatibility evaluations showed that the scaffolds, particularly those treated for 5 min, supported cell viability and proliferation without inducing cytotoxic effects. The molecular analysis indicated a favorable upregulation of chondrogenic genes such as SOX9 and COL2A1, and a downregulation of COL1A1, suggesting potential benefits for cartilage tissue engineering. These findings highlight that precise control over the duration of alkaline hydrolysis can significantly enhance PCL scaffold properties, suggesting a scalable and cost-effective method for scaffold optimization in regenerative medicine applications. The results pave the way for further in vivo studies to validate these promising in vitro findings and explore the clinical applicability of the optimized scaffolds.

Recent advancements in cartilage tissue engineering innovation and translation.

Articular cartilage was expected to be one of the first successfully engineered tissues, but today, cartilage repair products are few and they exhibit considerable limitations. For example, of the cell-based products that are available globally, only one is marketed for non-knee indications, none are indicated for severe osteoarthritis or rheumatoid arthritis, and only one is approved for marketing in the USA. However, advances in cartilage tissue engineering might now finally lead to the development of new cartilage repair products. To understand the potential in this field, it helps to consider the current landscape of tissue-engineered products for articular cartilage repair and particularly cell-based therapies. Advances relating to cell sources, bioactive stimuli and scaffold or scaffold-free approaches should now contribute to progress in therapeutic development. Engineering for an inflammatory environment is required because of the need for implants to withstand immune challenge within joints affected by osteoarthritis or rheumatoid arthritis. Bringing additional cartilage repair products to the market willrequire an understanding of the translational vector for their commercialization. Advances thus far can facilitate the future translation of engineered cartilage products to benefit the millions of patients who suffer from cartilage injuries and arthritides.

Induced pluripotent stem cells in cartilage tissue engineering: a literature review.

A literature search was conducted using scientific search engines, PubMed, MEDLINE, and Google Scholar databases with the terms 'Cartilage tissue engineering' and 'stem cells' to retrieve published literature on chondrogenic differentiation and tissue engineering using MSCs, ESCs, and hiPSCs. hiPSCs may provide an effective and autologous treatment for focal chondral lesions, though further research is needed to explore the potential of such technologies. This review has provided a comprehensive overview of these technologies and the potential applications for hiPSCs in regenerative medicine.

3D Bioprinting of Biomimetic Alginate/Gelatin/Chondroitin Sulfate Hydrogel Nanocomposites for Intrinsically Chondrogenic Differentiation of Human Mesenchymal Stem Cells.

3D-printed hydrogel scaffolds biomimicking the extracellular matrix (ECM) are key in cartilage tissue engineering as they can enhance the chondrogenic differentiation of mesenchymal stem cells (MSCs) through the presence of active nanoparticles such as graphene oxide (GO). Here, biomimetic hydrogels were developed by cross-linking alginate, gelatin, and chondroitin sulfate biopolymers in the presence of GO as a bioactive filler, with excellent processability for developing bioactive 3D printed scaffolds and for the bioprinting process. A novel bioink based on our hydrogel with embedded human MSCs presented a cell survival rate near 100% after the 3D bioprinting process. The effects of processing and filler concentration on cell differentiation were further quantitatively evaluated. The nanocomposited hydrogels render high MSC proliferation and viability, exhibiting intrinsic chondroinductive capacity without any exogenous factor when used to print scaffolds or bioprint constructs. The bioactivity depended on the GO concentration, with the best performance at 0.1 mg mL-1. These results were explained by the rational combination of the three biopolymers, with GO nanoparticles having carboxylate and sulfate groups in their structures, therefore, biomimicking the highly negatively charged ECM of cartilage. The bioactivity of this biomaterial and its good processability for 3D printing scaffolds and 3D bioprinting techniques open up a new approach to developing novel biomimetic materials for cartilage repair.

A regenerative approach for temporomandibular joint repair: An invitro and exvivo study.

Current clinical approaches to regenerate temporomandibular joint (TMJ) articulating cartilage defects only treat the symptoms (i.e. pain and dysfunction) and do not seek to restore joint integrity for long-term relief. Therefore, we investigated a novel self-assembling tissue-engineered cartilage to overcome this significant clinical issue for TMJ regenerative purposes. Examine the maturation of dynamic self-regenerating cartilage (dSRC) using auricular chondrocytes and evaluate a novel combinatorial approach with fractional laser treatment and dSRC implantation for TMJ cartilage repair. A suspension of 107 freshly harvested rabbit ear chondrocytes was cultured under a continuous reciprocating motion to form the dSRC. After 2, 4 and 8 weeks of culture, dSRC samples were stained with H&E, Safranin-O and Toluidine Blue. Immunohistochemistry (IHC) was performed for collagens type I and II. Channels (300-500 μm diameter and 1.2-1.5 mm depth) were created in six freshly harvested condyles using a fractional Erbium laser. Two groups were tested: dSRC in a laser-ablated lesion (experimental) and an empty laser-ablated channel (control). TMJ condyles were cultured for up to 8 weeks and analysed as described above. H&E staining showed a high cell density in dSRC compared to native cartilage. All dSRC groups demonstrated intense Safranin-O staining, indicating high glycosaminoglycan (GAG) production and intense Toluidine Blue staining showed high proteoglycan content. IHC confirmed that dSRC consisted predominantly of collagen type II. The experimental group showed improved cartilage repair at both time points compared to the empty channels. dSRC viability and successful matrix formation were demonstrated invitro. The combination of fractional laser ablation and dSRC implantation enhanced cartilage repair.

One-step soaking strategy toward mechanobiological double-network hydrogel with improving chondrogenesis capacity

Cartilage tissue engineering (CTE) is a promising strategy for addressing the persistent challenges in healing articular cartilage defects in the clinic, aiming to manufacture scaffolds with ideal mechanical characteristics that can provide a conducive microenvironment for the reconstruction or replacement of damaged cartilage defects. Easy operation, excellent mechanical strength, remarkable biocompatibility, and inherent capacity to promote cartilage formation are essential in CTE. This study designed a mechanobiological double-network (DN) hydrogel (KCS-PAA-Mn2+) through a one-step soaking strategy of immersing the composite hydrogel (KCS-PAA) of kartogenin (KGN)-conjugated short-chain chitosan (CS) covalent with polyacrylic acid (PAA) in manganese chloride (MnCl2) solution. Due to the strong physical interactions of CS chain-entanglement network and carboxylate-Mn2+ complex inducing polymer aggregation state transitions, the KCS-PAA-Mn2+ DN hydrogel exhibited exceptional mechanical characteristics, such as high tensile property (strength: 0.24 MPa at a strain of 552 %; toughness: 0.66 MPa), compressibility (strength: 51.98 MPa at a strain of 95 %; compressive modulus: 0.09 MPa), controllable swelling behavior (~327 %), and sustained drug release (>2 weeks). Moreover, in vitro biological studies demonstrated that the KCS-PAA-Mn2+ DN hydrogel not only promoted cell growth and proliferation but also enhanced the expression of genes specific to cartilage and the release of cartilage extracellular matrix (ECM) by bone mesenchymal stem cells (BMSCs), thus enabling a continuous concentration for a long period and persistently enhancing its chondrogenic efficiency. Overall, this soaking methodology reported here is universal to construct mechanically bioactive scaffolds that could expand their bio-applicability with simultaneous advantages of mechanical supports, tailorable swelling, sustainable drug release and long-lasting biological function, thus facilitating the advancement of cartilage-engineered hydrogel biomaterials to a higher level.