Stimuli-triggered hydrogel matrices for organoid engineering exhibit tri-modal responsiveness, demonstrating programmable structural transitions under thermal, pH, or optical excitation. Among them, temperature-sensitive hydrogel scaffolds are widely used in organoid culture. Temperature-sensitive hydrogels possess a unique molecular architecture containing both hydrophilic and hydrophobic functional groups. These dual-character components undergo dynamic intramolecular and intermolecular interactions with water molecules in response to thermal variations, ultimately triggering structural reorganization of the hydrogel’s three-dimensional network and consequent volumetric phase transitions (Wang et al., 2019). This thermal responsiveness is primarily attributed to a characteristic thermotropic phenomenon observed in certain polymer solutions, where aqueous solubility decreases progressively with temperature elevation. Upon reaching a critical threshold temperature, the system undergoes phase separation manifested by solution turbidity, while cooling below this transition point restores homogeneous transparency - a thermodynamic behavior formally designated as the Lower Critical Solution Temperature (Iyer et al., 2013). On the contrary, a part of the polymer is dissolved above a certain temperature. Below this temperature, the polymer solution undergoes phase separation and precipitation, called the upper critical dissolution temperature (Seuring and Agarwal, 2012). The low critical dissolution temperature and the upper critical dissolution temperature are important parameters for the interconversion of solutions in transparent and opaque states. Thermosensitive hydrogel scaffolds for organoid culture are usually regulated by a low critical dissolution temperature. For example: Matrigel, Mogengel, and BME, all derived from EHS cells, exist in solution form at 4°C and convert to gel from 22°C to 35°C. Like these hydrogels, the thermosensitive dECM hydrogel scaffolds were in solution from 4°C to 8°C and polymerized into the gel from 37°C (Zhu et al., 2023). In contrast, polyisocyanate (PIC)-based composite hydrogel scaffolds can form gels at 18°C (Kouwer et al., 2013).

Unlike temperature-sensitive hydrogels, pH-sensitive hydrogels generally contain weakly acidic or basic groups. After the environmental pH value or ionic strength changes, due to the difference in internal and external concentration, the gel water absorption swells or contracts, and the hydrogen bond formed between the polymers will ionize, causing discontinuous swelling changes in volume (Hendi et al., 2020). The pH-sensitive hydrogel scaffolds used for organoid culture include polyethylene glycol (PEG)-based hydrogels (Chrisnandy et al., 2022), hyaluronic acid (HA) hydrogels (Chen Y. et al., 2023), self-assembling peptide hydrogels (SAPHs) (Treacy et al., 2023), etc. The preparation methods of pH-responsive scaffolds include: 1. Crosslinking polymerization, including chemical initiator-initiated monomer crosslinking polymerization and crosslinking by radiation technology; 2. Graft copolymerization involves combining two chain segments with special properties that are typically incompatible, such as hydrophilic and hydrophobic, or acidic and basic. The characteristics of the resulting gel depend on the composition and length of both the backbone and side chains, as well as the number of side chains present; 3. Interpenetrating polymer technology; 4. Cross-linking of water-soluble polymers (Zhang and Wu, 2023).

Due to the advantages of dose adjustability, wavelength orthogonality, and spatiotemporal controllability, light has become a highly potential stimulation means to regulate the properties of hydrogels (Homma et al., 2021). Photosensitive hydrogels consist of a polymeric network and a photoreactive group, usually containing photochromic chromogenic groups that can undergo physical or chemical changes in response to light signals. There are three main mechanisms for the reaction of photosensitive hydrogels: 1. The photosensitive molecules in the photosensitive material convert light energy into heat energy, thereby increasing the temperature of the material. When the internal temperature of the gel reaches the phase transition condition, the gel will respond (Xing et al., 2016). 2. Photoresponsive hydrogels undergo programmable volumetric transitions through light-triggered ionic modulation. Upon photoactivation, photolabile moieties within the polymer network undergo photolytic cleavage, liberating ionic species that disrupt the Donnan equilibrium. This osmotic gradient drives compensatory mass transport phenomena, where controlled ion flux across the hydrogel-solvent interface induces reversible swelling/deswelling behavior via electrostatic repulsion force modulation (Dehghany et al., 2018). 3. Photochromic molecules are introduced into the hydrogel material of the polymer backbone as side groups or cross-linking agents. Due to the photosensitivity of these chromophores, their physicochemical properties, such as dipole moments and geometry, as well as the shape, structure, and properties of the macroscopic hydrogels, change due to expansion and contraction (Ji et al., 2020). Photosensitive hydrogels are also commonly used for organoid cultures, such as allyl sulfide hydrogel for intestinal organoids (Hushka et al., 2020); Broguiere et al. used a two-photon patterning technique to guide axons in a hyaluronic acid matrix by photopatterning nerve growth factors (Broguiere et al., 2020).

Organoid scaffolds can precisely regulate their mechanical and biochemical properties through different response mechanisms (temperature, pH, and light), which cause changes in the structure or properties of the materials. Thermosensitive hydrogels can precisely control the mechanical and biochemical properties of scaffolds through the use of temperature-responsive polymers. In terms of mechanical properties, when the temperature changes, the polymer chains undergo reversible hydrophilic-hydrophobic phase transitions, thereby dynamically adjusting the mechanical properties of the scaffold such as viscoelasticity and porosity (Zhao J. et al., 2022). In terms of biochemical properties, thermosensitive hydrogels can act as intelligent delivery carriers, and through temperature-responsive swelling and contraction behaviors, achieve controlled release of loaded growth factors, drugs, and other bioactive substances. This dynamic release characteristic not only avoids the burst release effect but also provides a continuous and stable biochemical microenvironment for organoids (Hasani-Sadrabadi et al., 2020). Unlike thermosensitive hydrogels, pH-sensitive hydrogels achieve dynamic regulation of the mechanical and biochemical properties of the scaffolds through polymer networks containing ion groups. In terms of mechanical properties, changes in environmental pH can dynamically alter the ionization state of the polymer chains, and by adjusting the electrostatic repulsion between molecular chains and the swelling equilibrium, precisely control the mechanical properties of the scaffold (Qiu and Park, 2001). In terms of biochemical property regulation, pH-dependent surface charge changes can not only respond to environmental stimuli to achieve controlled release of bioactive substances but also promote cell adhesion and proliferation by altering the surface electrical properties of the material (Ahmadian et al., 2021; Gupta et al., 2002). Different from the aforementioned two types of hydrogels, photosensitive hydrogels achieve regulation of the mechanical and biochemical properties of the scaffolds by introducing photosensitive groups. In terms of mechanical property regulation, ultraviolet or visible light irradiation can trigger photo-crosslinking or photolysis reactions, dynamically adjusting the crosslinking density of the polymer network, thereby achieving reversible regulation of the mechanical properties of the hydrogel such as viscoelasticity and network structure (Tsegay et al., 2022). In terms of biochemical property regulation, the photosensitive groups in the hydrogel can achieve light-controlled release of bioactive substances. That is, under specific wavelength light irradiation, the photosensitive groups in the hydrogel react, causing changes in the hydrogel structure and releasing the bioactive substances encapsulated within, thereby regulating the life activities of organoids (Zhao X. et al., 2022). Through the above-mentioned external stimulus-response mechanisms, organoid scaffolds can dynamically regulate their mechanical and biochemical properties. Therefore, on the basis of clearly classifying the response modes of the scaffolds, further exploration of the mechanical and biochemical properties of organoid scaffolds is of great significance for an in-depth understanding of the scaffold-cell interaction mechanism and optimization of the organoid culture system.

Organoid scaffolds have both mechanical and biochemical properties. Mechanical properties provide structural support for organoids, while biochemical properties provide bioactive substances required for the life activities of organoids.

The mechanical properties, biochemical characteristics, and response patterns of organoid scaffolds are key factors in regulating the formation, development, and maturation of organoids. Therefore, studying scaffold-based organoid culture systems and deeply analyzing the mechanical features, biochemical composition and dynamic responses of scaffolds to different culture systems are crucial for optimizing organoid culture models.

The methods for culturing organoids using hydrogels as scaffolds primarily encompass gel embedding, air-liquid interface culture, and suspension culture. Among these techniques, gel embedding is the most prevalent, comprising two principal approaches: the dome method and the cover culture method. Recently, some researchers have conducted a standardized study on the dome culture of organoids. They used Matrigel as an organoid scaffold and found that the temperature was 4°C for the best uniformity of the gel droplets, and the inoculum was 25 μL for the best organoid growth (Moon Hyun et al., 2024). The cover culture method is also frequently used in organoid cultures. Gel was added to the bottom of the culture plate, and after the gel had been set, cells were spread on the gel and covered with a layer of gel above the cells to form a three-layer culture system. This method is not only suitable for tumor organoid culture but also can be used to co-culture tumor organoids and immune cells to evaluate the killing ability of different types of immune cells on tumor and infected organoids (Ota et al., 2024; Sharma et al., 2021). For organoid culture at the air-liquid interface, firstly, the diluted gel was added to a Transwell chamber, and after it solidified, gel suspension containing organoids was added. After the suspension had solidified, the Transwell chamber was placed in a Petri dish and a medium suitable for organoid growth was added to it, thus forming an air-liquid culture system (Neal et al., 2018). In addition to the above two culture methods, organoids can also be cultivated by suspension culture. In this method, organoids are suspended in a medium containing 3%–10% matrix glue or other 5% matrix preparations, and the organoids are stirred by pipetting to prevent them from sticking to the walls of the culture vessel. For example, Yumiko et al. successfully cultured colorectal organoids and CRC (colorectal cancer) organoids using suspension culture. The experimental results showed that the suspension culture organoids were similar in morphology to the organoids cultured by the traditional embedding method. Furthermore, the generated CRC organoids exhibited histological features and genetic heterogeneity similar to primary CRC (Hirokawa et al., 2021).

It is worth noting that different culture methods have distinct requirements for scaffold properties. In long-term gel-encapsulated culture, the degradation rate of the scaffold needs to be well-matched with the tissue regeneration process too rapid degradation can lead to structural collapse, while too slow degradation can impede the remodeling of the extracellular matrix (Place et al., 2009; Lutolf and Hubbell, 2005). For air-liquid interface culture, the scaffold should possess biochemical characteristics that promote epithelial polarity growth (such as collagen and laminin modification) and a porous structure that facilitates the exchange of gases and nutrients (Chen and Schoen, 2019). In suspension culture systems, the viscosity of the scaffold must be precisely controlled; too low viscosity may cause cell sedimentation and aggregation, while too high viscosity can restrict the diffusion of oxygen and nutrients (Hirokawa et al., 2021). Therefore, for different culture methods, the mechanical and biochemical properties of the scaffold need to be precisely designed and optimized according to their specific requirements.

The organoid scaffolds enhance the regulatory ability of the cultivation system for complex microenvironments through their dynamic responses to external stimuli. Among them, the thermosensitive hydrogel scaffolds demonstrate unique advantages in the embedding method: when the minimum critical dissolution temperature is set between 30°C and 32°C, the temperature-induced sol-gel transformation not only enables gentle cell encapsulation but also ensures the stability of the gel structure and cell activity (Klouda, 2015). For cultivation systems that need to adapt dynamically to the metabolic microenvironment, the pH-sensitive hydrogel can regulate the degradation rate by responding to the changes in the acidity and alkalinity of the culture environment in real-time. This characteristic makes it highly valuable in suspension cultivation systems (Schmaljohann, 2006). In cases where precise control of the solid-liquid interface is required, such as in gas-liquid interface cultivation, the photosensitive hydrogel stands out due to its controllable cross-linking properties: by irradiating with ultraviolet or blue light, the surface curing degree of the scaffold can be precisely controlled, maintaining a stable interface structure while ensuring the sufficient diffusion of nutrients in the deep layers (Fairbanks et al., 2009; Yue et al., 2015). These three types of responsive scaffolds, through different stimulus-response mechanisms, jointly construct a dynamically adjustable microenvironment system for organoid cultivation.

The introduction of biotechnological engineering has brought a revolutionary breakthrough in the cultivation of organoids. Biotechnology enables precise regulation of the microenvironment of organoids, not only enhancing their simulation accuracy but also breaking through the limitations of traditional culture methods. This allows organoids to achieve scalable expansion and cultivation while maintaining tissue specificity. Micro-pattern technology precisely controls cell adhesion and spatial arrangement through surface chemical modification or physical constraints, promoting uniform growth of organoids. For instance, Jiang et al. developed a micro-pattern agarose scaffold, which significantly outperformed the traditional matrix gel dome culture system in terms of size uniformity and cell composition for liver organoids derived from pluripotent stem cells (Jiang et al., 2022). 3D printing technology precisely regulates the mechanical properties, biochemical signals, and spatial structure of the scaffold to provide an appropriate microenvironment for organoids, promoting their growth and maturation (Ji and Guvendiren, 2017). For example, Alonzo et al. designed a ring-shaped hydrogel scaffold that not only maintains structural stability for a long time but also promotes the proliferation and maturation of cardiac organoids (Alonzo et al., 2022). Microfluidic technology precisely regulates fluid shear force, solute gradients (such as growth factors and drug concentration distribution), oxygen partial pressure levels, and mechanical stimulation (such as simulating intestinal peristalsis, vascular shear stress, etc.) to simulate the complex microenvironment in the body, thereby revealing the response mechanism of organoids to external stimuli in a dynamic microenvironment (Saorin et al., 2023). For instance, Quintard et al. developed a microfluidic platform, which not only achieved efficient encapsulation of organoids but also dynamically perfused to form functional vascular networks (Quintard et al., 2024). Bioreactor technology introduces mechanical stimulation and optimizes the culture environment, significantly enhancing the amplification efficiency and functional maturity of organoids. Compared to static culture, bioreactors can optimize nutrient and oxygen supply, reduce metabolic waste accumulation, and support the formation of vascular networks (Licata et al., 2023). For example, Ye et al. developed a micro-rotating bioreactor, which increased the proliferation rate of liver organoids by 5.2 times (Ye et al., 2024). It is worth noting that these biotechnological engineering techniques exhibit a strong synergistic effect. The combination of 3D printing and microfluidic technology can construct a heart organoid chip with vascular networks (Zhang et al., 2016); the combination of micro-pattern technology and bioreactors can achieve high-throughput organoid production (Khan et al., 2021). This multi-technology integration strategy is driving organoid models towards higher simulation accuracy and standardization, providing powerful tools for disease modeling, drug development, and regenerative medicine research.

By selecting appropriate cultivation methods, choosing organoid scaffolds that match the mechanical and biochemical properties of the target tissues, and combining them with biotechnological approaches, it is possible to more accurately simulate the tumor microenvironment and achieve the clinical translation of organoid technology. Different tumor organoids require specific cultivation methods to better simulate their in vivo microenvironment. For example, the air-liquid interface cultivation method provides a physiological microenvironment for tissue-air contact, offering a more similar culture system to the in vivo microenvironment for respiratory system models such as airway and lung organoids (Joo et al., 2024; Ekanger et al., 2025). The embedding method can provide three-dimensional structural support for organoids and simulate the mechanical properties of extracellular matrix, suitable for the cultivation of most solid tumor organoids. The mechanical and biochemical properties of the scaffolds have significant impacts on the morphology, proliferation, differentiation, and drug response of tumor organoids (Curvello et al., 2023). Studies have shown that the mechanical properties of the tumor microenvironment differ significantly from those of normal tissues. For instance, the elastic modulus of breast cancer tissue is typically 4–12 kPa, much higher than the 0.5–2 kPa of normal breast tissue (Paszek et al., 2005). Therefore, the mechanical parameters of the scaffolds need to be highly matched with the target tumor tissue to truly simulate the tumor microenvironment (Casey et al., 2017). Additionally, the porosity and three-dimensional structure characteristics of the scaffolds are related to the diffusion of nutrients and cell migration. Optimized biomimetic porous scaffolds can promote the formation of vascular networks in organoids, thereby better simulating the in vivo microenvironment of tumors. In terms of biochemical properties, the extracellular matrix components of the scaffolds need to simulate the molecular composition of the natural tumor microenvironment. Studies have shown that scaffolds rich in collagen are more conducive to the proliferation of breast cancer organoids, while scaffolds rich in fibronectin and laminin are more suitable for constructing the microenvironment of liver cancer organoids (Sokol et al., 2016; Saheli et al., 2018). Moreover, by precisely regulating the release of growth factors and drugs, dynamic regulation of the proliferation, differentiation, and drug response behaviors of tumor organoids can be achieved. The introduction of biotechnological approaches (such as microfluidic technology, and 3D printing technology) significantly improves the biomimetic performance of the scaffolds. Microfluidic technology precisely regulates fluid shear force, solute gradients (such as growth factor and drug concentration distribution), oxygen pressure levels, and mechanical stimuli (such as simulating intestinal peristalsis, vascular shear stress, etc.), simulating the complex tumor microenvironment in vivo (Sontheimer-Phelps et al., 2019). 3D printing technology precisely regulates the mechanical properties, biochemical signals, and spatial structure of the scaffolds to achieve a highly biomimetic simulation of tumor tissue heterogeneity (Wang et al., 2024). In summary, by optimizing the organoid cultivation system, not only can the reliability of cancer mechanism research and drug screening be improved, but also the application of organoid technology in clinical practice can be promoted.

Matrigel is derived from Engelbreth-Holm-swarm mouse sarcoma and is rich in ECM proteins. Proteomics analysis showed that Matrigel contains more than 1800 kinds of proteins (Hughes et al., 2010). The main components of Matrigel include laminin, collagen IV, nestin, and heparan sulfate proteoglycan (Aisenbrey and Murphy, 2020), which are ubiquitous in early embryonic development, so Matrigel can mimic the microenvironment of early embryos. Matrigel has become the gold-standard biomaterial for establishing three-dimensional tissue models across multiple organ systems, such as tumor organoids (Qiang et al., 2023; Berk, 2022), heart organoids (Drakhlis et al., 2021), esophageal organoids (Ko et al., 2022), ureteral organoids (Shi et al., 2023), and liver organoids (Takebe et al., 2013) (Figure 2). In addition, Matrigel was used for almost all organoids successfully cultured for the first time. For example: In 2009, Sato et al. isolated crypts from the small intestine of mice and mixed them with Matrigel. Subsequently, the mixed suspension was seeded on culture plates using the dome method, and a small intestinal organoid medium containing factors such as R-spondin 1, EGF, and Noggin was added. Finally, intestinal organoids were successfully grown. Their findings validated that individual Lgr⁵⁺ intestinal stem cells possess the capability to generate intestinal organoids (Sato et al., 2009); In 2013, Lancaster et al. first induced human pluripotent stem cells (hPSCs) to form embryoid bodies in diluted Matrigel-coated plates. These embryoid bodies were further differentiated into neural structures in a neural induction medium, which was then encapsulated in Matrigel and transferred to a rotary bioreactor containing a differentiation medium for further induction into mature brain organoids. Brain organoids generated in this way have discrete but interconnected brain regions and exhibit features of human cortical development (Lancaster et al., 2013); In 2022, Kageyama et al. isolated epithelial and mesenchymal cells from mouse embryonic skin and cultured them in suspension in an Advanced DMEM/F-12 medium containing 1% Matrigel. Finally, hair follicle organoids were successfully induced, and the hair shaft was able to grow to 3 mm in length (Kageyama et al., 2022).

Although Matrigel has been widely used due to its many advantages, it also has many drawbacks. Given the complexity and inherent uncertainty associated with Matrigel, as well as the variability in its composition (Kleinman and Martin, 2005; Cruz-Acuna and Garcia, 2017; Polykandriotis et al., 2008), the biochemical characteristics of Matrigel can differ not only between batches but also within the same batch. For example, compositional uncertainty. One study showed that growth factors such as IGF-1 and EGF were expressed at quantifiable levels, on the order of nanograms per milliliter, but were not detected in four later independent Matrigel batches (Vukicevic et al., 1992). At the same time, the concentration of growth factors varied between batches, for example, the concentration of FGF-2 and platelet-derived growth factors varied by orders of magnitude between batches; Uncertainty of mechanical properties. A previous study showed an average elastic modulus of 400–420 Pa for two batches of Matrigel. However, the average elastic modulus of the third batch of material was twice as large (840 Pa) (Soofi et al., 2009). Finally, Matrigel is derived from mouse tumor cells, has potential immunogenicity, and its complex composition makes it difficult to fully mimic the microenvironment of specific human tissues, which limits its application in clinical transplantation and regenerative medicine.

dECM hydrogel scaffolds can be used to construct scaffold materials suitable for organoid growth by removing cellular components from tissues or organs and retaining their ECM. The ECM not only contains bioactive substances required for organoid growth but also can provide mechanical support for it. Its components contain a variety of proteins, such as fibronectin, collagen, elastin, and laminin, and also contain GAGs and a variety of bioactive factors, which play an important role in organoid culture (Navaee et al., 2023) (Figure 3). There are variations in the composition of the extracellular matrix (ECM) across different tissues, and these variations enable the ECM to meet the specific functional demands of each tissue type. Consequently, the composition of decellularized ECM (dECM) hydrogel scaffolds varies among different tissues. For instance, cardiac decellularized scaffolds primarily consist of collagen, non-collagenous proteins, elastin, proteoglycans, and glycosaminoglycans. Among these components, collagen is crucial for maintaining the mechanical strength and structural integrity of the heart, whereas elastin and proteoglycans contribute significantly to preserving the elasticity and functionality of the heart (Simsa et al., 2021). Unlike brain tissue-derived decellularized scaffolds, liver-decellularized scaffolds are mainly composed of collagen, laminin, fibronectin, and GAGs. Among these components, collagen and GAGs play a key role in maintaining the structure and function of the liver, while laminin and fibronectin promote the adhesion and proliferation of hepatocytes (Liu et al., 2025).

Currently, there are many tissue types of dECM hydrogel scaffolds for organoid culture, for example: Kim et al. prepared gastrointestinal organoid scaffolds from decellularized treated stomachs and small intestines. Compared with Matrigel, this scaffold contains more proteins derived from native gastric and intestinal tissues, which are involved in gastrointestinal-specific functions such as digestion, intestinal absorption, and gastric acid secretion, indicating that this scaffold can provide a microenvironment closer to the in vivo environment for gastrointestinal organoids. The results showed that the gastrointestinal organoids cultured on the scaffold were comparable to those cultured in Matrigel, in structural and functional characteristics (Kim et al., 2022a). In addition, another of his studies showed that intestinal organoid cell death was observed in acellular hydrogels derived from other tissues such as skin, lymph, heart, and muscle (Kim et al., 2022b). Together, these two studies demonstrated that the effect of the ECM microenvironment on organoid development is tissue-specific; Chen et al. fabricated a mouse-derived decellularized liver scaffold and used this scaffold to culture primary mouse cholangiocytes to successfully construct a functional liver organoid. The results show that these functional biliary organoids not only express a wealth of specific biomarkers but also exhibit a typical biliary tree-like structure with specific bile secretion and transport functions (Chen J. et al., 2023); Song et al. prepared a uterocervical extracellular matrix hydrogel from paracancerous cervical tissue from patients with cervical squamous cell carcinoma and used it for the culture of cervical squamous cell carcinoma organoids. Their results showed that compared with Matrigel, the uterocervical extracellular matrix hydrogel contained higher levels of human cervical tissue-specific proteins, the cultured organoids retained more cervical cancer-related oncogenes and signaling pathways and exhibited more obvious drug resistance, which could more accurately identify patients with drug resistance (Song et al., 2024). In addition to the above-mentioned organoids, retinal organoids (Berber et al., 2022), endodermal organoids (Giobbe et al., 2019), kidney organoids (Geng et al., 2022), etc. can also be cultured by dECM hydrogel scaffolds.

dECM hydrogel scaffolds retain the native tissue structure and components of the ECM by removing the cellular components and are therefore tissue-specific and less immunogenic. At the same time, the retained ECM components reduce the introduction of exogenous substances and avoid external interference. It has been widely used in tissue repair and medical cosmetology. However, dECM hydrogel scaffolds still have some shortcomings in organoid culture: 1. Compared with Matrigel, dECM hydrogel scaffolds still have some shortcomings in the culture effect of most organoids; 2. The quality of the stent is affected by the health status of the donor; 3. Residual chemicals and enzymes during decellularization may be cytotoxic; 4. The preparation method is complex; 5. The cells could not be completely removed; 6. There are batch differences (Talbot and Caperna, 2015). These limiting factors, to some extent, affect the widespread application of dECM hydrogel scaffolds in organoid culture.

Given the limitations of organoid scaffolds mentioned above, researchers have begun to focus on recombinant protein and peptide hydrogel scaffolds with clear components, hoping to construct fully synthetic scaffolds suitable for organoid growth. At present, the exploration of recombinant protein and peptide hydrogel scaffolds has been quite extensive.

In order to further explore the effect of the mechanical properties of scaffolds on organoid culture, researchers have turned to synthetic hydrogel scaffolds. We classified synthetic hydrogels into synthetic polymer hydrogels and natural polymer hydrogels according to the source of the synthetic materials.

Because different types of stents have their shortcomings, researchers adopt a strategy of compositing different scaffold materials to avoid these defects. Many materials are often combined with Matrigel to prepare organoid scaffolds. For example, Matrigel was combined with a medical carbon fiber (CF) scaffold. CF scaffolds have grooves along the pores, which can effectively adsorb nutrients in the medium and promote intercellular interactions. At the same time, CF scaffolds are highly stable and do not degrade to toxic substances or cause pH changes during organoid culture. Studies have shown that the composite scaffold composed of Matrigel and CF can improve the proliferation and differentiation efficiency of iPSC in organoids (Tejchman et al., 2020); Three-dimensional recombinant spider silk microfibrous scaffolds assembled from recombinant full-length human laminin and composite with Matrigel for brain organoid culture. The results showed that the composite scaffold effectively alleviated the hypoxia problem of brain organoids and promoted the growth and differentiation of brain organoids (Sozzi et al., 2022); Composite scaffolds for culturing human spinal cord organoids (ehSC) were prepared by wrapping the ventral spinal cord signaling Shh agonist (SAG) with porous chitosan microspheres (PCSM) and coating the PCSM with a layer of Matrigel. The results showed that EHscs could form progenitor cells and neurons with significant domain specificity, construct dorsoventral spinal-like cells, and exhibit functional calcium activity (Xue et al., 2023). In addition to being composite with Matrigel, it can also be composite with other materials. For example, Gomez-Alvarez et al. mixed PM peptide hydrogel with EndoECM hydrogel to produce an organoid scaffold suitable for the growth of endometrial organoids (hEOs). The results showed that the morphology of hEOs cultured on the scaffold was similar to that in Matrigel, and the scaffold effectively promoted the formation, proliferation, and differentiation of the organoids (Gomez-Alvarez et al., 2024).

The organoid composite scaffold has many advantages, such as: 1. It has good biocompatibility and can minimize the risk of local toxicity and adverse reactions; 2. It has good mechanical properties. The mechanical properties of the scaffolds can be adjusted by combining different materials; 3. Versatility. However, organoid composite scaffolds also have some drawbacks. On the one hand, organoid composite scaffolds have potential immune responses. On the other hand, the functional composite research of composite scaffold materials needs to comprehensively consider the mutual matching between various properties, which increases the complexity and difficulty of the research (Table 1).