Chondrogenic stimulation in mesenchymal stem cells using scaffold‐based sustained release of platelet‐rich plasma

Hydrogel-Based 3D Bioprinting Technology for Articular Cartilage Regenerative Engineering

Articular cartilage is an avascular tissue with very limited capacity of self-regeneration. Trauma or injury-related defects, inflammation, or aging in articular cartilage can induce progressive degenerative joint diseases such as osteoarthritis. There are significant clinical demands for the development of effective therapeutic approaches to promote articular cartilage repair or regeneration. The current treatment modalities used for the repair of cartilage lesions mainly include cell-based therapy, small molecules, surgical approaches, and tissue engineering. However, these approaches remain unsatisfactory. With the advent of three-dimensional (3D) bioprinting technology, tissue engineering provides an opportunity to repair articular cartilage defects or degeneration through the construction of organized, living structures composed of biomaterials, chondrogenic cells, and bioactive factors. The bioprinted cartilage-like structures can mimic native articular cartilage, as opposed to traditional approaches, by allowing excellent control of chondrogenic cell distribution and the modulation of biomechanical and biochemical properties with high precision. This review focuses on various hydrogels, including natural and synthetic hydrogels, and their current developments as bioinks in 3D bioprinting for cartilage tissue engineering. In addition, the challenges and prospects of these hydrogels in cartilage tissue engineering applications are also discussed.

Progress of Platelet Derivatives for Cartilage Tissue Engineering

Articular cartilage has limited self-regeneration ability for lacking of blood vessels, nerves, and lymph that makes it a great challenge to repair defects of the tissue and restore motor functions of the injured or aging population. Platelet derivatives, such as platelet-rich plasma, have been proved effective, safe, and economical in musculoskeletal diseases for their autologous origin and rich in growth factors. The combination of platelet derivatives with biomaterials provides both mechanical support and localized sustained release of bioactive molecules in cartilage tissue engineering and low-cost efficient approaches of potential treatment. In this review, we first provide an overview of platelet derivatives and their application in clinical and experimental therapies, and then we further discuss the techniques of the addition of platelet derivatives and their influences on scaffold properties. Advances in cartilage tissue engineering with platelet derivatives as signal factors and structural components are also introduced before prospects and concerns in this research field. In short, platelet derivatives have broad application prospects as an economical and effective enhancement for tissue engineering–based articular cartilage repair.

Chitosan-coated Selenium nanoparticles enhance the efficiency of stem cells in the neuroprotection of streptozotocin-induced neurotoxicity in male rats

Alzheimer's disease (AD) is one of the common neurodegenerative diseases characterized by memory impairment. The protective effects of stem cell-based therapy have been reported in AD. In this study, it was assumed that Chitosan-coated Selenium nanoparticles (ChSeNPs) increase the efficiency of stem cells in the attenuation of neurotoxicity in the rat AD model. The AD model was induced using Streptozotocin (STZ) and treated by the adipose-derived mesenchymal stem cells (AMSCs) and SeNPs/ChSeNPs (0.4 mg/kg). Passive avoidance learning and recognition memory were assessed using shuttle box and novel object recognition tasks. The amyloid-beta deposition, the injected cells' homing and survival, antioxidant capacity, and BDNF concentration were evaluated using the histological, biochemical, and ELISA methods. The results showed that the combined administration of ChSeNPs and AMSCs is more effective in increasing the step-through latency and discrimination index than administering SeNPs and stem cells. Combined therapy caused a significant increase in antioxidant capacity that ChSeNPs was more effective than SeNPs, while AMSCs beside SeNPs had a greater effect on BDNF levels compared to conventional treatment of nanoparticles or AMSCs alone. Ultimately, the homing and survival of the transplanted AMSCs were greater in the group that received both stem cells and ChSeNPs. Taken together, it seems that the administration of ChSeNPs enhances the efficiency of transplanted stem cells in decreasing the neurotoxicity induced by STZ through an increase in the antioxidant capacity.

Injectable Composite Systems Based on Microparticles in Hydrogels for Bioactive Cargo Controlled Delivery

Engineering drug delivery systems (DDS) aim to release bioactive cargo to a specific site within the human body safely and efficiently. Hydrogels have been used as delivery matrices in different studies due to their biocompatibility, biodegradability, and versatility in biomedical purposes. Microparticles have also been used as drug delivery systems for similar reasons. The combination of microparticles and hydrogels in a composite system has been the topic of many research works. These composite systems can be injected in loco as DDS. The hydrogel will serve as a barrier to protect the particles and retard the release of any bioactive cargo within the particles. Additionally, these systems allow different release profiles, where different loads can be released sequentially, thus allowing a synergistic treatment. The reported advantages from several studies of these systems can be of great use in biomedicine for the development of more effective DDS. This review will focus on in situ injectable microparticles in hydrogel composite DDS for biomedical purposes, where a compilation of different studies will be analysed and reported herein.