A Chondrosphere-Based Scaffold Free Approach to Manufacture an In Vitro Articular Cartilage Model

Multimodal layer-by-layer nanoparticles: a breakthrough in gene and drug delivery for osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumours in children and adolescents, frequently arising from mesenchymal tissue in the distal femur. It is highly aggressive, often metastasising to the lungs. Current treatments, which include surgery combined with neoadjuvant chemotherapy and radiotherapy, are often unsatisfactory due to the inability of surgery to control metastasis and the side effects and drug resistance associated with chemotherapy. Thus, there is an urgent need for new treatment technologies. This study explored the use of nanoparticles for gene and drug delivery in osteosarcoma treatment. The nanoparticles were composed of biodegradable and biocompatible polymers, chitosan and PLGA, and were loaded with miRNA-34a, a short RNA molecule that functions as a tumour suppressor by inducing cell cycle arrest and apoptosis in osteosarcoma cells. Recognising that the co-delivery of multiple drugs can enhance treatment efficacy while reducing systemic toxicity and drug resistance, three additional classes of nanoparticles were developed by adding doxorubicin and resveratrol to the chitosan-PLGA-miRNA-34a core. A layer-by-layer technique was employed to create a bilayer nanocoating using pectin and chitosan as polyelectrolytes, for encapsulating the therapeutic payloads. The manufactured nanoparticles were tested on U2OS and Saos-2 cells to assess cell viability, metabolic activity, and morphology before and after treatment. Cells were treated in both two-dimensional cultures and three-dimensional osteosarcoma spheroids, creating a biomimetic cellular model. Increased apoptotic activity and disruption of cellular functions were primarily observed with nanoparticles co-delivering miRNA-34a and drugs, particularly those functionalised with the LbL nanocoating, as confirmed by PCR analysis.

Hydrogel-based and spheroid-based autologous chondrocyte implantation of the knee show similar 2-year functional outcomes: An analysis based on the German Cartilage Registry (KnorpelRegister DGOU)

PURPOSE

To compare short-term patient-reported outcomes (PRO) of two contemporary matrix-associated autologous chondrocyte implantation (M-ACI) products for the treatment of large articular cartilage defects of the knee.

METHODS

A retrospective, registry-based, matched-pair analysis was performed, comparing PRO of patients undergoing isolated M-ACI with either Spherox™, a spheroid-based ACI (Sb-ACI), or NOVOCART™ Inject, a hydrogel-based ACI product (Hb-ACI), for a focal full-thickness cartilage defect of the knee ≥4 cm2. Matching parameters included age, sex, body mass index, defect size, defect localization, symptom duration and previous surgeries. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) score were obtained up to the 24-month follow-up. The total KOOS response rate and percentage of patients attaining a substantial clinical benefit (SCB) in KOOS subscores were calculated.

RESULTS

A total of 45 patients per group were matched. The response rate after 24 months was not significantly different between the groups (Sb-ACI 64.4% vs. Hb-ACI 82.2%, p = 0.057). The number of patients with a SCB at 24 months was not significantly different in any KOOS subscore, despite significantly higher improvement of the total KOOS (14.8 ± 16.2 vs. 21.5 ± 15.4, p = 0.047) and KOOS pain in the Hb-ACI group (12.2 ± 18.6 vs. 20.6 ± 19.1, p = 0.037). The IKDC score in the Hb-ACI group was significantly higher at the 12- and 24-month follow-up (60.7 ± 20.2 vs. 70.9 ± 18.0, p = 0.013).

CONCLUSION

The response rate and number of patients achieving an SCB were not significantly different between patients treated with Sb-ACI or Hb-ACI. Both procedures can achieve favourable 2-year PRO. Hb-ACI was associated with better PRO between 1 and 2 years postoperatively; however, the clinical relevance of this benefit is yet to be proven.

LEVEL OF EVIDENCE

III, Retrospective comparative study.

Enhanced chondrogenic potential in GelMA-based 3D cartilage model via Wnt3a surface immobilization

Cartilage tissue engineering aims to develop functional substitutes for treating cartilage defects and osteoarthritis. Traditional two-dimensional (2D) cell culture systems lack the complexity of native cartilage, leading to the development of 3D regenerative cartilage models. In this study, we developed a 3D model using Gelatin Methacryloyl (GelMA)-based hydrogels seeded with Y201 cells, a bone marrow mesenchymal stem cell line. The model investigated chondrogenic differentiation potential in response to Wnt3a stimulation within the GelMA scaffold and validated using known chondrogenic agonists. Y201 cells demonstrated suitability for the model, with increased proteoglycan content and upregulated chondrogenic marker expression under chondrogenic conditions. Wnt3a enhanced cell proliferation, indicating activation of the Wnt/β-catenin pathway, which plays a role in cartilage development. GelMA hydrogels provided an optimal scaffold, supporting cell viability and proliferation. The 3D model exhibited consistent responses to chondrogenic agonists, with TGF-β3 enhancing cartilage-specific extracellular matrix (ECM) production and chondrogenic differentiation. The combination of Wnt3a and TGF-β3 showed synergistic effects, promoting chondrogenic differentiation and ECM production. This study presents a 3D regenerative cartilage model with potential for investigating cartilage biology, disease mechanisms, and drug screening. The model provides insights into complex cartilage regeneration mechanisms and offers a platform for developing therapeutic approaches for cartilage repair and osteoarthritis treatment.

A cytokine-induced spheroid-based in vitro model for studying osteoarthritis pathogenesis

Given the lack of in vitro models faithfully reproducing the osteoarthritis (OA) disease on-set, this work aimed at manufacturing a reliable and predictive in vitro cytokine-based Articular Cartilage (AC) model to study OA progression. Cell spheroids of primary human fetal chondrocytes (FCs) and h-TERT mesenchymal stem cells differentiated chondrocytes (Y201-C) were analysed in terms of growth kinetics, cells proliferation and apoptosis over 10 days of culture, in healthy condition or in presence of cytokines (interleukin-1ß, -6 and TNF-α). Then, the spheroids were assembled into chondrospheres using a bottom-up strategy, to obtain an in vitro cytokines-induced OA model. The resulting chondrospheres were evaluated for gene expression and anabolic ECM proteins. Compared to the healthy environment, the simulated OA environment induced chondrocyte hyperproliferation and apoptotic pathway, decreased expression of anabolic ECM proteins, and diminished biosynthetic activity, resembling features of early-stage OA. These characteristics were observed for both Y201-C and HC at high and low concentrations of cytokines. Both HC and Y201-C demonstrated the suitability for the manufacturing of a scaffold-free in vitro OA model to facilitate studies into OA pathogenesis and therapeutic strategies. Our approach provides a faithful reproduction of early-stage osteoarthritis, demonstrating the ability of obtaining different disease severity by tuning the concentration of OA-related cytokines. Given the advantages in easy access and more reproducible performance, Y201-C may represent a more favourable source of chondrocytes for establishing more standardized protocols to obtain OA models.

An In Vitro Engineered Osteochondral Model as Tool to Study Osteoarthritis Environment

Osteoarthritis (OA) is a joint degenerative pathology characterized by mechanical and inflammatory damages affecting synovium, articular cartilage (AC), and subchondral bone (SB). Several in vitro, in vivo, and ex vivo models are developed to study OA, but to date the identification of specific pharmacological targets seems to be hindered by the lack of models with predictive capabilities. This study reports the development of a biomimetic in vitro model of AC and SB interface. Gellan gum methacrylated and chondroitin sulfate/dopamine hydrogels are used for the AC portion, whereas polylactic acid functionalized with gelatin and nanohydroxyapatite for the SB. The physiological behavior of immortalized stem cells (Y201s) and Y201s differentiated in chondrocytes (Y201-Cs), respectively, for the SB and AC, is demonstrated over 21 days of culture in vitro in healthy and pathological conditions, whilst modeling the onset of cytokines-induced OA. The key metrics are: lower glycosaminoglycans production and increased calcification given by a higher Collagen X content, in the AC deep layer; higher expression of pro-angiogenic factor (vegf) and decreased expression of osteogenic markers (coll1, spp1, runx2) in the SB. This novel approach provides a new tool for studying the development and progression of OA.

Articular Cartilage Regeneration through Bioassembling Spherical Micro-Cartilage Building Blocks

Articular cartilage lesions are prevalent and affect one out of seven American adults and many young patients. Cartilage is not capable of regeneration on its own. Existing therapeutic approaches for articular cartilage lesions have limitations. Cartilage tissue engineering is a promising approach for regenerating articular neocartilage. Bioassembly is an emerging technology that uses microtissues or micro-precursor tissues as building blocks to construct a macro-tissue. We summarize and highlight the application of bioassembly technology in regenerating articular cartilage. We discuss the advantages of bioassembly and present two types of building blocks: multiple cellular scaffold-free spheroids and cell-laden polymer or hydrogel microspheres. We present techniques for generating building blocks and bioassembly methods, including bioprinting and non-bioprinting techniques. Using a data set of 5069 articles from the last 28 years of literature, we analyzed seven categories of related research, and the year trends are presented. The limitations and future directions of this technology are also discussed.

Valuable effect of Manuka Honey in increasing the printability and chondrogenic potential of a naturally derived bioink

Hydrogel-based bioinks are the main formulations used for Articular Cartilage (AC) regeneration due to their similarity to chondral tissue in terms of morphological and mechanical properties. However, the main challenge is to design and formulate bioinks able to allow reproducible additive manufacturing and fulfil the biological needs for the required tissue. In our work, we investigated an innovative Manuka honey (MH)-loaded photocurable gellan gum methacrylated (GGMA) bioink, encapsulating mesenchymal stem cells differentiated in chondrocytes (MSCs-C), to generate 3D bioprinted construct for AC studies. We demonstrated the beneficial effect of MH incorporation on the bioink printability, leading to the obtainment of a more homogenous filament extrusion and therefore a better printing resolution. Also, GGMA-MH formulation showed higher viscoelastic properties, presenting complex modulus G∗ values of ∼1042 ​Pa, compared to ∼730 ​Pa of GGMA. Finally, MH-enriched bioink induced a higher expression of chondrogenic markers col2a1 (14-fold), sox9 (3-fold) and acan (4-fold) and AC ECM main element production (proteoglycans and collagen).

The Developing Field of Scaffold-Free Tissue Engineering for Articular Cartilage Repair

Articular cartilage is critical for proper joint mobility as it provides a smooth and lubricated surface between articulating bones and allows for transmission of load to underlying bones. Extended wear or injury of this tissue can result in osteoarthritis, a degenerative disease affecting millions across the globe. Because of its low regenerative capacity, articular cartilage cannot heal on its own and effective treatments for injured joint restoration remain a challenge. Strategies in tissue engineering have been demonstrated as potential therapeutic approaches to regenerate and repair damaged articular cartilage. Although many of these strategies rely on the use of an exogenous three-dimensional scaffolds to regenerate cartilage, scaffold-free tissue engineering provides numerous advantages over scaffold-based methods. This review highlights the latest advancements in scaffold-free tissue engineering for cartilage and the potential for clinical translation.