Composite scaffold of micronized porcine cartilage/poly(lactic‑co‑glycolic acid) enhances anti-inflammatory effect

High paracrine activity of hADSCs cartilage microtissues inhibits extracellular matrix degradation and promotes cartilage regeneration

Due to its unique structure, articular cartilage has limited self-repair capacity. Microtissues are tiny tissue clusters that can mimic the function of target organs or tissues. Using cells alone for microtissue construction often results in the formation of necrotic cores. However, the extracellular matrix (ECM) of native cartilage can provide structural support and is an ideal source of microcarriers. Autologous adipose-derived mesenchymal stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) are widely used in cartilage tissue engineering. In this study, we fabricated microcarriers and compared the behavior of two homologous cell types in the microcarrier environment. The microcarrier environment highlighted the advantages of ADSCs and promoted the proliferation and migration of these cells. Then, ADSCs microtissues (ADSCs-MT) and BMSCs microtissues (BMSCs-MT) were fabricated using a three-dimensional dynamic culture system. In vitro and in vivo experiments verified that the cartilage regeneration ability of ADSCs-MT was significantly superior to that of BMSCs-MT. Transcriptomics revealed that ADSCs-MT showed significantly lower expression levels of ECM degradation, osteogenesis, and fibrocartilage markers. Finally, the protective effect of microtissues on inflammatory chondrocytes was validated. Overall, the ADSCs-MT constructed in this study achieved excellent cartilage regeneration and could be promising for the autologous application of cartilage microtissues.

Polyelectrolytes for Environmental, Agricultural, and Medical Applications

In recent decades, polyelectrolytes (PELs) have attracted significant interest owing to a surge in research dedicated to the development of new technologies and applications at the biological level. Polyelectrolytes are macromolecules of which a substantial portion of the constituent units contains ionizable or ionic groups. These macromolecules demonstrate varied behaviors across different pH ranges, ionic strengths, and concentrations, making them fascinating subjects within the scientific community. The aim of this review is to present a comprehensive survey of the progress in the application studies of polyelectrolytes and their derivatives in various fields that are vital for the advancement, conservation, and technological progress of the planet, including agriculture, environmental science, and medicine. Through this bibliographic review, we seek to highlight the significance of these materials and their extensive range of applications in modern times.

Targeting Inflammation and Regeneration: Scaffolds, Extracellular Vesicles, and Nanotechnologies as Cell-Free Dual-Target Therapeutic Strategies

Osteoarthritis (OA) affects over 250 million people worldwide and despite various existing treatment strategies still has no cure. It is a multifactorial disease characterized by cartilage loss and low-grade synovial inflammation. Focusing on these two targets together could be the key to developing currently missing disease-modifying OA drugs (DMOADs). This review aims to discuss the latest cell-free techniques applied in cartilage tissue regeneration, since they can provide a more controllable approach to inflammation management than the cell-based ones. Scaffolds, extracellular vesicles, and nanocarriers can be used to suppress inflammation, but they can also act as immunomodulatory agents. This is consistent with the latest tissue engineering paradigm, postulating a moderate, controllable inflammatory reaction to be beneficial for tissue remodeling and successful regeneration.

Tissue-Specific Hydrogels for 3D Printing and Potential Application in Peripheral Nerve Regeneration

Decellularized extracellular matrix hydrogel (dECM-G) has demonstrated its significant tissue-specificity, high biocompatibility, and versatile utilities in tissue engineering. However, the low mechanical stability and fast degradation are major drawbacks for its application in 3D printing. Herein, we report a hybrid hydrogel system consisting of dECM-Gs and photocrosslinkable gelatin methacrylate (GelMA), which resulted in significantly improved printability and structural fidelity. These pre-mixed hydrogels retained high bioactivity and tissue-specificity due to their containing dECM-Gs. More specifically, it was realized that the hydrogel containing dECM-G derived from porcine peripheral nerves (GelMA/pDNM-G) effectively facilitated neurite growth and Schwann cell migration from 2D cultured dorsal root ganglion explants. The nerve cells were also encapsulated in the GelMA/pDNM-G hydrogel for 3D culture or underwent cell-laden bioprinting with high cell viability. The preparation of such GelMA/dECM-G hydrogels enabled the recapitulation of functional tissues through extrusion-based bioprinting, which holds great potential for applications in regenerative medicine.

Application of bone and cartilage extracellular matrices in articular cartilage regeneration

Articular cartilage has an avascular structure with a poor ability for self-repair; therefore, many challenges arise in cases of trauma or disease. It is of utmost importance to identify the proper biomaterial for tissue repair that has the capability to direct cell recruitment, proliferation, differentiation, and tissue integration by imitating the natural microenvironment of cells and transmitting an orchestra of intracellular signals. Cartilage extracellular matrix (cECM) is a complex nanostructure composed of divergent proteins and glycosaminoglycans (GAGs), which regulate many functions of resident cells. Numerous studies have shown the remarkable capacity of ECM-derived biomaterials for tissue repair and regeneration. Moreover, given the importance of biodegradability, biocompatibility, 3D structure, porosity, and mechanical stability in the design of suitable scaffolds for cartilage tissue engineering, demineralized bone matrix (DBM) appears to be a promising biomaterial for this purpose, as it possesses the aforementioned characteristics inherently. To the best of the authors' knowledge, no comprehensive review study on the use of DBM in cartilage tissue engineering has previously been published. Since so much work is needed to address DBM limitations such as pore size, cell retention, and so on, we decided to draw the attention of researchers in this field by compiling a list of recent publications. This review discusses the implementation of composite scaffolds of natural or synthetic origin functionalized with cECM or DBM in cartilage tissue engineering. Cutting-edge advances and limitations are also discussed in an attempt to provide guidance to researchers and clinicians.

Hybrid and Composite Scaffolds Based on Extracellular Matrices for Cartilage Tissue Engineering

IMPACT STATEMENT

Scaffolds fabricated from extracellular matrix (ECM) derivatives are composed of conducive structures for cell attachment, proliferation, and differentiation, but generally do not have proper mechanical properties and load-bearing capacity. In contrast, scaffolds based on synthetic biomaterials demonstrate appropriate mechanical strength, but the absence of desirable biological properties is one of their main disadvantages. To integrate mechanical strength and biological cues, these ECM derivatives can be conjugated with synthetic biomaterials. Hence, hybrid scaffolds comprising both advantages of synthetic polymers and ECM derivatives can be considered a robust vehicle for tissue engineering applications.

Interactions at scaffold interfaces: Effect of surface chemistry, structural attributes and bioaffinity

Effective regenerative medicine relies on understanding the interplay between biomaterial implants and the adjoining cells. Scaffolds contribute by presenting sites for cellular adhesion, growth, proliferation, migration, and differentiation which lead to regeneration of tissues over desired periods of time. The fabrication and recruitment of scaffolds often fail to consider the interactions that occur at the interfaces, thereby risking rejection. This lack of knowledge on interfacial microenvironments and related exchanges often causes reduced cellular interactions, poor cell survival and intervention failure. Successful regenerative therapy requires scaffolds with bespoke biocompatibility, optimum pore structure, and cues for cell attachments. These factors determine the development of cellular affinity in scaffolds. For biomedical applications, a detailed understanding of scaffolds and their interfaces is required for better tuning of biomaterials to suit the microenvironments. In this review, we discuss the role of biointerfaces with a focus on surface chemistry, pore structure, scaffold hydro-affinity and their biointeractions. An understanding of the effect of scaffold interfacial properties is crucial for enhancing the progress of tissue engineering towards clinical applications.

Enhancement of neural stem cell survival, proliferation and differentiation by IGF-1 delivery in graphene oxide-incorporated PLGA electrospun nanofibrous mats

The mammalian central nervous system has a limited ability for self-repair under injury conditions.