Bionic Biphasic Composite Scaffold with Osteochondrogenic Factors for Regeneration of Full-Thickness Osteochondral Defect

Advances in the pathology and treatment of osteoarthritis

BACKGROUND

Osteoarthritis (OA), a widespread degenerative joint disease, predominantly affects individuals from middle age onwards, exhibiting non-inflammatory characteristics. OA leads to the gradual deterioration of articular cartilage and subchondral bone, causing pain and reduced mobility. The risk of OA increases with age, making it a critical health concern for seniors. Despite significant research efforts and various therapeutic approaches, the precise causes of OA remain unclear.

AIM OF REVIEW

This paper provides a thorough examination of OA characteristics, pathogenic mechanisms at various levels, and personalized treatment strategies for different OA stages. The review aims to enhance understanding of disease mechanisms and establish a theoretical framework for developing more effective therapeutic interventions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review systematically examines OA through multiple perspectives, integrating current knowledge of clinical presentation, pathological mechanisms, and associated signaling pathways. It assesses diagnostic methods and reviews both pharmacological and surgical treatments for OA, as well as emerging tissue engineering approaches to manage the disease. While therapeutic strategies such as exercise, anti-inflammatory drugs, and surgical interventions are employed to manage symptoms and modify joint structure, none have been able to effectively halt OA's advancement or achieve long-lasting symptom relief. Tissue engineering strategies, such as cell-seeded scaffolds, supportive matrices, and growth factor delivery, have emerged as promising approaches for cartilage repair and OA treatment. To combat the debilitating effects of OA, it is crucial to investigate the molecular basis of its pathogenesis and seek out innovative therapeutic targets for more potent preventive and treatment strategies.

Multifunctional vitamin D-incorporated PLGA scaffold with BMP/VEGF-overexpressed tonsil-derived MSC via CRISPR/Cas9 for bone tissue regeneration

Guiding endogenous regeneration of bone defects using biomaterials and regenerative medicine is considered an optimal strategy. One of the effective therapeutic approaches involves using transgene-expressed stem cells to treat tissue destruction and replace damaged parts. Among the various gene editing techniques for cells, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) is considered as a promising method owing to the increasing therapeutic potential of cells by targeting specific sites. Herein, a vitamin D-incorporated poly(lactic-co-glycolic acid) (PLGA) scaffold with bone morphogenetic protein 2 (BMP2)/vascular endothelial growth factor (VEGF)-overexpressed tonsil-derived MSCs (ToMSCs) via CRISPR/Cas9 was introduced for bone tissue regeneration. The optimized seeding ratio of engineered ToMSCs on the scaffold demonstrated favorable immunomodulatory function, angiogenesis, and osteogenic activity in vitro. The multifunctional scaffold could potentially support stem cell in vivo and induce the transition from M1 to M2 macrophage with magnesium hydroxide and vitamin D. This study highlights the improved synergistic effect of a vitamin D-incorporated PLGA scaffold and a gene-edited ToMSCs for bone tissue engineering and regenerative medicine.

Osteochondral tissue engineering in translational practice: histological assessments and scoring systems

Osteochondral lesions are common pathological alterations in synovial joints. Different techniques have been designed to achieve osteochondral repair, and tissue-engineered osteochondral grafts have shown the most promise. Histological assessments and related scoring systems are crucial for evaluating the quality of regenerated tissue, and the interpretation and comparison of various repair techniques require the establishment of a reliable and widely accepted histological method. To date, there is still no consensus on the type of histological assessment and scoring system that should be used for osteochondral repair. In this review, we summarize common osteochondral staining methods, discuss the criteria regarding high-quality histological images, and assess the current histological scoring systems for osteochondral regeneration. Safranin O/Fast green is the most widely used staining method for the cartilage layer, whereas Gomori and Van Gieson staining detect new bone formation. We suggest including the graft-host interface and more sections together with the basic histological information for images. An ideal scoring system should analyze both the cartilage and bone regions, especially for the subchondral bone plate. Furthermore, histological assessments should be performed over a longer period of time to minimize discrepancies caused by defect size and animal species.

Advanced Composites Inspired by Biological Structures and Functions in Nature: Architecture Design, Strengthening Mechanisms, and Mechanical-Functional Responses

The natural design and coupling of biological structures are the root of realizing the high strength, toughness, and unique functional properties of biomaterials. Advanced architecture design is applied to many materials, including metal materials, inorganic nonmetallic materials, polymer materials, and so on. To improve the performance of advanced materials, the designed architecture can be enhanced by bionics of biological structure, optimization of structural parameters, and coupling of multiple types of structures. Herein, the progress of structural materials is reviewed, the strengthening mechanisms of different types of structures are highlighted, and the impact of architecture design on the performance of advanced materials is discussed. Architecture design can improve the properties of materials at the micro level, such as mechanical, electrical, and thermal conductivity. The synergistic effect of structure makes traditional materials move toward advanced functional materials, thus enriching the macroproperties of materials. Finally, the challenges and opportunities of structural innovation of advanced materials in improving material properties are discussed.

Strategy of a cell-derived extracellular matrix for the construction of an osteochondral interlayer

Osteochondral defects pose an enormous challenge due to the lack of an effective repair strategy. To tackle this issue, the importance of a calcified cartilage interlayer (CCL) in modulating osteochondral regeneration should be valued. Herein, we proposed that an extracellular matrix (ECM) derived from a suitable cell source might efficiently promote the formation of calcified cartilage. To the end, cell sheets from four kinds of cells, including bone marrow mesenchymal stem cells (BMSCs), pre-osteoblasts (MC3T3), chondrocytes (Cho), and artificially induced hypertrophic chondrocytes (HCho), were obtained by seeding the cells on electrospun fibrous meshes, followed by decellularization to prepare decellularized ECMs (D-ECMs) for BMSC re-seeding and differentiation studies. For cell proliferation, the BMSC-derived D-ECM exhibited the strongest promotion effect. For inducing the hypertrophic phenotype of re-seeded BMSCs, both the BMSC-derived and HCho-derived D-ECMs demonstrated stronger capacity in up-regulating the depositions of related proteins and the expressions of marker genes, as compared to the MC3T3-derived and Cho-derived D-ECMs. Accordingly, from the histological results of their subcutaneous implantation in rats, both the BMSC-derived and HCho-derived D-ECMs displayed obvious Masson's trichrome and Safranin-O/Fast-Green staining colors simultaneously, representing the characteristics related to osteogenesis and chondrogenesis. Differently, MC3T3-derived and Cho-derived D-ECMs were mainly detected during the osteogenic or chondrogenic expression, respectively. These findings confirmed that the BMSC-derived D-ECM could induce hypertrophic chondrocytes, though being a little inferior to the HCho-derived D-ECM. Overall, the BMSC-derived D-ECM could be a potential material in constructing the interlayer for osteochondral tissue engineering scaffolds to improve the regeneration efficiency.

Delivery of Mesenchymal Stem Cell in Dialdehyde Methylcellulose-Succinyl-Chitosan Hydrogel Promotes Chondrogenesis in a Porcine Model

Due to the limitation in the current treatment modalities, such as secondary surgery in ACI and fibrocartilage formation in microfracture surgery, various scaffolds or hydrogels have been developed for cartilage regeneration. In the present study, we used sodium periodate to oxidize methylcellulose and formed dialdehyde methylcellulose (DAC) after dialysis and freeze-drying process, DAC was further mixed with succinyl-chitosan (SUC) to form an DAC-SUC in situ forming hydrogel. The hydrogel is a stiffness, elastic-like and porous hydrogel according to the observation of SEM and rheological analysis. DAC-SUC13 hydrogel possess well cell-compatibility as well as biodegradability. Most bone marrow mesenchymal stem cells (BM-pMSCs) were alive in the hydrogel and possess chondrogenesis potential. According to the results of animal study, we found DAC-SUC13 hydrogel can function as a stem cell carrier to promote glycosaminoglycans and type II collagen synthesis in the osteochondral defects of porcine knee. These findings suggested that DAC-SUC13 hydrogel combined with stem cell is a potential treatment for cartilage defects repair in the future.