Fig. 5.

Overview of hydrogel systems used in the construction of bone/cartilage organoids. The figure illustrates four distinct hydrogel systems-Matrigel, Collagen-hydrogel, PEG-hydrogel, and DNA-hydrogel-used for supporting the development of bone and cartilage organoids. a Matrigel contains key extracellular matrix components such as laminin, collagen IV, and entactin, facilitating stem cell adhesion and proliferation through integrin and growth factor receptor interactions.⁵¹ b Collagen-hydrogel involves the incorporation of isolated mesenchymal stem cells (MSCs) into collagen fibers, forming a scaffold that promotes cell differentiation and tissue development.⁵³ c PEG-hydrogel features a transglutaminase (TG) cross-linking mechanism using PEG and hyaluronic acid (HA) to form a functionalized hydrogel environment that supports the differentiation of bone marrow stromal cells (BMSCs) and hematopoietic progenitor cells (HPSCs).⁵⁶ d DNA-hydrogel combines RGD-silk fibroin and a DNA system to create a microsphere hydrogel structure, which can be integrated into a microfluidic chip for precise tissue engineering applications⁶⁰