Cell encapsulated biomaterials for translational medicine

Abstract

Biomaterial supported cell encapsulation matrices have demonstrated superior properties for enhancing biological functionality, making them highly significant for translational medicine across multiple therapeutic applications. This review examined how biomaterials interact with cellular therapies, including stem cells, immune cells, and fibroblasts across single-cell, multicellular, and core-shell structures. The biomaterial capsule plays a key role in improving cell viability, immune protection, and supporting tissue-specific interactions. Furthermore, this review highlights current trends in microfluidics, 3D printing, in situ preparation, and electrospraying self-assembly, each method offering different advantages for cell encapsulation matrices. Microfluidics allows precise control of capsule size and uniformity, making it suitable for single-cell and core-shell encapsulation. The 3D printing technologies empower accurate cell placement to build multicellular structures that mimic native tissue organization. In situ preparation directly encapsulates cells within the target tissue. Collectively, these techniques significantly influence the physical, chemical, and biological properties of encapsulated cells. Additionally, we discuss various biomaterials including natural proteins, polysaccharides, and synthetic polymers, each material offers unique benefits in terms of biocompatibility and biodegradability. The integration of living cells with biomaterial matrix cell encapsulation systems greatly exhibits mechanical strength, high porosity, and controlled drug release. Importantly, this review emphasises the dual role of the biomaterial capsule in cancer therapy, which enhances anti-tumor immune responses and promotes tissue regeneration, with a focus on bone, skin, neural tissue, liver, vascular structures, and skeletal muscle repair. In conclusion, cell-encapsulated biomaterials are a versatile platform supporting both cancer immunotherapy and regenerative medicine, underscoring their wide range of biomedical applications.

Keywords: Biomaterials; Cancer therapy; Cell encapsulation; Immune cell; Tissue regeneration.

Graphical abstract

Fig. 1

Schematic illustration of a biomaterial-based cell encapsulation platform designed for dual applications in cancer therapy and tissue regeneration. The diagram presents a multifunctional therapeutic system in bioactive cells (fibroblast cell, stem cell, platelet cells, neutrophil cell, B cell, and T cell) encapsulated with polymer matrix (collagen, silk fibroin, cyclodextrin, sodium alginate, polyethylene glycol (PEG), polylactic acid (PLA), polyvinyl alcohol (PVA), and polycaprolactone (PCL)). This encapsulated system serves two primary purposes. The left-side platform facilitates cancer therapy by delivering therapeutic agents that inhibit tumor growth and kill the cancer cells. The right side platform supports tissue regeneration of various tissues, including bone grafts, skin tissue, and neuronal network regeneration. (Scheme of the diagram created by bioself using Cinema 4D and Adobe Illustrator software).

Fig. 2

(a&b) Depicts the cells interacting with a polymer during the cell encapsulation process using a layer-by-layer (LbL) self-assembly method. Reproduced with permission from Ref. [240], Copyright 2018, Wiley-VCH. (c) Immunofluorescence microscopy images of iPSC capsules, labelled with Hoechst (blue), SOX-2 antibody (green), NANOG antibody (red), and OCT-4 antibody (yellow). Scale bar 100 μm. Reproduced with permission from Ref. [241], Copyright 2024, Wiley-VCH. (d) Histological analysis of iPSC capsules was performed at days 2, 4, 6, 8, and 10 post-encapsulation, and structural changes were evaluated by hematoxylin and eosin (H&E) staining. Scale bar 50 μm. Reproduced with permission from Ref. [241], Copyright 2024, Wiley-VCH. (e) Shows the single-cell strategies of cell analysis in intracellular compound capture and heterogeneity study of different biomedical applications, Reproduced from Ref. [242], Copyright 2024, Wiley-VCH.

Fig. 3

(a) Description of the multicore microcapsule system of a single domain and molecule mixed active agent of cell encapsulated structure. Reproduced with permission from Ref. [243], Copyright 2023 Elsevier. (b) Schematic diagram of microcapsule (A–D) multi-stimuli-responsive microcapsules with customizable controlled-release, (E–G) schematic diagram of pH and temperature-based fabrication method of controlled-drug release mechanism. Reproduced with permission from Ref. [243], Copyright 2023 Elsevier. (c) Microcapsules analysis of different pH levels (6.5–8.6) medium with changes in morphological structure. Scale bar 10 μm. Reproduced with permission from Ref. [243], Copyright 2023 Elsevier.

Fig. 4

(a) The design of the microfluidic device in the schematic illustration of the PDMS-based microfluidic device used for fabricating alginate microgels. Reproduced with permission from Ref. [245]. Copyright 2020, Elsevier. (b) Formation of cell-encapsulating microgel in a laminar flow of alginate solution is disrupted into droplets via a flow-focusing junction. Acetic acid present in the oil phase diffuses into these aqueous droplets, triggering the release of Ca²⁺ ions from Ca-EDTA complexes, which in turn initiates alginate gelation. Reproduced with permission from Ref. [245], Copyright 2020, Elsevier. (c) The addition of PFO to the oil phase removes surfactants, destabilising the droplet interface. Reproduced with permission from Ref. [245], Copyright 2020, Elsevier. (d) Alginate microgels are then transferred into an aqueous phase. Reproduced with permission from Ref. [245], Copyright 2020, Elsevier. (e) Rapid gelation driven by Ca²⁺ cross-linking enables the encapsulation of cells within the microgels. By promptly collecting the encapsulated cells, high cell viability is maintained by minimizing prolonged exposure to acidic conditions. Reproduced with permission from Ref. [245]. Copyright 2020, Elsevier. (f) Confocal microscopy images at high magnification show MSCs encapsulated in RGD-modified alginate microgels and cultured in proliferation medium. Live and dead cells were visualised using calcein and ethidium homodimer staining, respectively. The encapsulated MSCs proliferated over time and eventually migrated out of the microgels. Despite proliferation, cells retained a spherical shape due to the stiffness of the alginate matrix. Reproduced with permission from Ref. [245], Copyright 2020, Elsevier. (g) Confocal images of MSCs stained with Syto 9 nuclei dye show continued proliferation within the microgels, indicated by increasing cell numbers. Reproduced with permission from Ref. [245], Copyright 2020, Elsevier. (h) Quantification of the average diameter of cell clusters within the microgels over the culture period. Reproduced with permission from Ref. [245]. Copyright 2020, Elsevier. (i&j) Cell distribution and DNA analysis of MSCs encapsulated within the microgels were denoted at different time points. Reproduced with permission from Ref. [245]. Copyright 2020, Elsevier. (k) Microfluidic confinement platform for cell invasion into various types of granular materials, such as microfluidic spherical, fragmentation-ridged, and emulsification spherical structures. Reproduced with permission from Ref. [244]. Copyright 2024, Wiley-VCH. (l) The layer-by-layer microfluidics, superhydrophobic surfaces, and 3D bioprinting utilise cell encapsulation systems. Reproduced with permission from Ref. [246]. Copyright 2020, Wiley-VCH.

Fig. 5

(a) 3D printed capsule device designed for islet delivery to treat diabetic mice without the use of immunosuppressants. Reproduced with permission from Ref. [247], Copyright 2022, ACS. (b) Schematic diagram of gastrointestinal targeting capsules filled with an aqueous solution. These capsules protect their contents during gastrointestinal transit in the stomach, early intestine (pH < 7), and late intestine or colon (pH > 7). The insoluble body and lid are made using DLP 3D printing, while the soluble enteric locking cap is produced via FDM 3D printing with a water-soluble filament. Reproduced from Ref. [248], Copyright 2024, Wiley-VCH. (c) Schematic representation (i–v) Different capsule structures, (vi-vii) Capsules photographs images. Reproduced from Ref. [249], Copyright 2022, Frontiers. (d) Capsule surface images with and without cell coating, including side, bottom, and top views of the FDM-based 3D printed capsule structure. Reproduced from Ref. [248], Copyright 2024, Wiley-VCH. (e) 3D printing of cell capsule in self-healing hydrogel elongation (top), brightfield images (middle), and fluorescent images (bottom) (i) Attachment of MSC spheroids in a media reservoir, (ii) Transfer of spheroids into a self-healing hydrogel, (iii) Deposition of spheroids within the hydrogel by releasing vacuum from the micropipette tip. Scale bars 250 μm. Reproduced from Ref. [285], Copyright 2021, Nature communications. (f) 3D printed spheroids assemble (i) Multi-layer cone-shaped geometry (FITC-labelled spheroids), (ii) Layered rings of distinct MSC spheroid populations (FITC and rhodamine-labelled). Scale bars 250 μm. Reproduced from Ref. [285], Copyright 2021, Nature communications.

Fig. 6

Different types of biomaterials including natural proteins, polysaccharides, and synthetic polymers.

Fig. 7

(a&b) Biomaterial-based different sizes of cell encapsulation such as macroencapsulation, microencapsulation, nanoencapsulation, and small molecules interact with cell encapsulation. Reproduced from Ref. [252] Copyright 2023 Elsevier.

Fig. 8

(a) Silk fibroin-based design of dual-network hydrogels with tunable surface rigidity for controlling chondrogenic differentiation in cartilage defect repair with DNA content of soft moderate, and stiff. Reproduced with permission from Ref. [254], Copyright 2024, Wiley-VCH. (b) Sericin-based biomaterial: (i) silk sericin structure of α-helix, β-sheet, and random coil, (ii) cellular adhesion and growth behaviour, (iii) regulation of cell function, and (iv) biomedical applications. Reproduced with permission from Ref. [255], Copyright 2024, Wiley-VCH.

Fig. 9

(a&b) Sources and structural characteristics of collagen with the cross-linking process and biomedical applications. Reproduced with permission from Ref. [253], copyright, 2022 Wiley-VCH. (c) Keratin-based different materials designed for tissue engineering applications Reproduced from Ref. [256] Copyright 2022, Elsevier. (d) Elastin-like polypeptide (ELP) illustration of linear and branched peptides for secondary structure transition (intramolecular process) followed by coacervation (intermolecular process) with encapsulated drug. Reproduced with permission from Ref. [257] copyright 2016 ACS.

Fig. 10

(a) Schematic diagram of hyaluronic acid applications in various fields. Reproduced from Ref. [258], Copyright 2024, Springer. (b) Schematic diagram illustrating the aqueous core-shell capsule formation process, including the cross-linking mechanism and covalent and non-covalent bonds between alginate (ALG), polyethyleneimine (PEI), and alginate dialdehyde (ADA). Light microscopy images of the liquefied capsules are shown the core stained green, ALG and ADA layers being transparent and colourless, and the PEI layer stained pink. Reproduced with permission from Ref. [259], Copyright 2024, ASC. (c) Calcium chloride concentrations of 1 %, 2.5 %, 5 %, 10 %, and 25 % were combined with sodium alginate concentrations of 0.1 %, 0.25 %, 0.5 %, and 1 %. For enhanced visualization, a 0.5 % trypan blue solution was mixed to find the capsule degradation morphology. Fluorescence imaging was then performed on alginate capsules encapsulating 5 × 10³ DiI-labelled C3H10T1/2 cells. Scale bars 500 μm. Reproduced from Ref. [260], Copyright 2023, Appl. Sci. (d) Sodium alginate formation of hydrogel physical and chemical cross-linking of various approaches. Reproduced with permission from Ref. [261], Copyright 2025, Elsevier.

Fig. 11

(a) Schematic diagram of the preparation of microcapsules using alginate-chitosan loaded with ornidazole and doxycycline drug molecules. Reproduced with permission from Ref. [262], Copyright 2023, Elsevier. (b) Chitosan capsule directly or indirectly treats the stomach gastric with mucoadhesive properties. Reproduced with permission from Ref. [263], Copyright 2024, Elsevier. (c) Chitosan used prebiotics encapsulation of postbiotic microcapsules for preventing and treating colitis in dual pH-sensitive oral targeted drug delivery. Reproduced with permission from Ref. [262], Copyright 2023, Elsevier. (d) Chitosan-based microcapsule applications in multiple fields. Reproduced with permission from Ref. [262], Copyright 2023, Elsevier. (e) Overview of cellulose structures with functionalization of different processes. Reproduced from Ref. [264], Copyright 2023, RSC. (f) The cyclodextrin structure, applications, and bioactive compounds of anti-inflammatory drugs encapsulated in the cyclodextrin molecules. Reproduced with permission from Ref. [265], Copyright 2024, Elsevier, and Reproduced with permission from Ref. [266], Copyright 2021, Biomolecules.

Fig. 12

(a) Schematic diagram of cells with polymer-mixed encapsulated matrix. (b) PEG activated circulating system of the human body (Antibodies; C3a and C5a, complement fragments; C3a R and C5a R, complement fragments receptors; LTRs, Leukotrienes; PAF, Platelet activating factor; TXA2, Thromboxane A2; CARPA, complement activation-related pseudoallergy). Reproduced with permission from Ref. [267], Copyright 2022, Elsevier. (c) The PVA capsule interacted with the cancer cells. Reproduced with permission from Ref. [268], Copyright 2021, Elsevier.

Fig. 13

(a) Mechanical strength, (b) compressive modulus (kPa), and (c) degradation profiles of pristine CS/SF and CS/SF/NFs at different concentrations of 0.5 %, 1 %, and 2 %. (d) Biocompatibility assessment: live/dead staining images of control, pristine CS/SF, CS/SF/NFs 0.5 %, CS/SF/NFs 1 %, and CS/SF/NFs 2 %, along with quantitative analysis using the CCK-8 assay. Scale bar 100 μm. Reproduced with permission from Ref. [307], Copyright 2022, Elsevier. (e) Tensile stress (MPa), (f) Young's modulus (MPa), (g) Biocompatibility, (h) Cell viability, and (i) Degradation behaviour of PCL/Gel composite matrices with different ratios (PCL/Gel-1, PCL/Gel-2, PCL/Gel-3, PCL/Gel-4, PCL/Gel-5, and PCL/Gel-6). Microscopic scale bar 200 μm. Reproduced with permission from Ref. [308], Copyright 2021, Elsevier. (j) Porosity, (k) compressive strength (kPa), (l) Young's modulus (kPa), (m) Degradation, (n) Storage modulus (kPa), and (o) Quantitative cell viability analysis of PVA/SF formulations (PVA75:SF25, PVA50:SF50, and PVA25:SF75). Data are expressed as mean ± S.D. (n = 5). Reproduced with permission from Ref. [108], Copyright 2025, Elsevier. Statistical significance was assessed using two-way ANOVA followed by Tukey's post hoc test (∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001).

Fig. 14

(a) Schematic diagram of biomaterials with different cellular units. Reproduced from Ref. [58], Copyright 2022, Elsevier. (b) Fibrous mats with varying degrees of structural compactness. Reproduced from Ref. [58], Copyright 2022, Elsevier. (c) Cell and biomaterial interactions of mechanical signals, including stiffness, external dynamic forces, surface patterns, and matrix dimensionality. Reproduced from Ref. [58], Copyright 2022 (d) Schematic diagram of biomaterial matrix-mediated cellular responses and cell-mediated matrix remodelling. Reproduced from Ref. [58], Copyright 2022, Elsevier.

Fig. 15

Schematic diagram of cell-matrix interaction in the biomedical applications of both cell-free and cell-loaded hydrogel. Reproduced from Ref. [250], Copyright 2021 Springer Nature.

Fig. 16

(a) Endothelial cell interactions of differentiation between physiological environment (normal cell line) and tumor environments (cancer cell line). Reproduced from Ref. [271], Copyright 2021 Frontiers in Pharmacology. (b) Cell encapsulation of functional organ implantation into the body. (c) Schematic diagram of targeted cancer stem cell (CSC) therapies in biomedical engineering, highlighting strategies such as biomarker targeting, tumor microenvironment modulation, signalling pathway inhibition, and differentiation therapy. Reproduced with permission from Ref. [227] Copyright 2025, Elsevier.

Fig. 17

(a) The immune system consists of various immune cells that play distinct roles in immune responses. Innate immune responses are primarily mediated by macrophages, dendritic cells, neutrophils, and natural killer (NK) cells (left). In contrast, adaptive immune responses involve T cells and B cells (right). Macrophages exhibit diverse functional phenotypes, with M1 macrophages activated by IL-4 and IL-10, while TNF-α and IFN-γ activate M2 macrophages. Reprinted with permission from Ref. [272], Copyright 2025, Wiley-VCH. (b) Biomaterial-based immune cells interacted with acute and chronic inflammation processes. Reprinted with permission from Ref. [272], Copyright 2025, Wiley-VCH.

Fig. 18

In vitro angiogenic evaluation of HUVECs cultured on various scaffolds: (a) schematic diagram of the synthesis of GP (GelMA hydrogel), DGP (DFO@PLGA-GelMA), and EDGP scaffolds (DFO@PLGA/EVs-GelMA). (b) HUVEC cell migration was assessed using a transwell assay. Scale bar 200 μm. (c) Quantification of transmigrated cells for each scaffold group. (d) QRT-PCR was performed for molecular assessment of angiogenic activity of HIF-1α and VEGF on days 3 and 7. (e) Western blot analysis by protein level for HIF-1α and VEGF. (f) mRNA expression levels of macrophage polarization markers (Arg1, CD163, IL-1β, and iNOS) were measured by qRT-PCR. Reproduced from Ref. [310], Copyright 2025, Elsevier. In vitro osteogenic evaluation of MSCs cultured on different scaffolds: (g) Schematic of the transwell co-culture system. (h–i) ALP staining and quantitative analysis of GP, DGP, and EDGP scaffolds for days 7 and 14. (j–k) ARS staining and quantitative analysis of GP, DGP, and EDGP scaffolds for days 14 and 21. Scale bar 500 μm. (l–m) Osteogenic gene expression (ALP, Runx2, Col1A1, OCN, OPN) in MSCs analysed by qRT-PCR after 7 and 14 days. (n) Protein expression of ALP, Runx2, Col1A1, OCN, and OPN osteogenic markers was analysed by Western blot. Reproduced from Ref. [310], Copyright 2025, Elsevier. All quantitative data are represented as mean ± SD (n = 4). Statistical significance is indicated as ∗∗p < 0.01, ∗∗∗p < 0.001, and ∗∗∗p < 0.0001.

Fig. 19

(a) Schematic diagram of stem cell isolation and expansion process for in vitro tissue engineering applications. (b) Schematic diagram of stem cell aggregate (i) Liquid core/solid shell encapsulation increases aggregation of facilitates the mass transit immunological isolation. (ii) Encapsulating stem cells in non-adhesive hydrogels enhances mass transit of immunological isolation. (iii) Encapsulating stem cells in sticky hydrogels containing integrin- and matrix metalloproteinase (MMP) binding sites enhances stem cell attachment while allowing for mass transit of macromolecules and immunological separation. Reproduced from Ref. [273], Copyright 2014, Bioresearch. (c) Schematic diagram of a microfluidic method for producing stem cell-loaded microcapsules for bone healing using core-shell microcapsules. Reproduced from Ref. [274], Copyright 2022, Nano-Micro Lett. (d) Schematic illustration of the extracellular and intracellular reactive oxygen species (ROS) environment, showcasing the mechanism of hMSCs functionality in cell proliferation and differentiation. Reproduced with permission from Ref. [275], Copyright 2024, Elsevier. (e) Different types of living cells used in drug delivery systems for various therapeutic applications. (f) Illustration of (anti-programmed death-ligand1) aPD-L1-crosslinked nanogels conjugated onto platelet surfaces. The polydopamine-modified PD-L1 platform demonstrated no significant impact on the viability of the decorated platelet cells. To enhance the aPD-L1 loading capacity of this platelet-based delivery system without compromising the platelets' normal function, disulfide-containing bis-N-hydroxy succinimide was employed to cross-link aPD-L1, forming uniform nanogels. These nanogels were conjugated onto platelet surfaces and cleaved in response to increased reductive activity following platelet activation. This mechanism facilitated the targeted transport of aPD-L1 to residual tumors while minimizing off-target effects during chemotherapy. Reproduced with permission from Ref. [276], Copyright 2023, Elsevier.

Fig. 20

Schematic diagram of several compositions of smart nanoencapsulation strategies for cancer therapy. Reproduced from Ref. [277] Copyright 2025, Frontiers in Bioengineering and Biotechnology.

Fig. 21

(a) Chemotherapy treatment using biomaterials to destroy tumor cells. Reproduced from Ref. [278], Copyright 2023, Nature Communications. (b) Radiotherapy treatment using biomaterial capsule to destroy tumor cells. Reproduced with permission from Ref. [279], Copyright 2019, WILEY-VCH.

Fig. 22

(a) Semi-permeable membrane used for micro and macrocapsules for cell transplantation. (b Schematic diagram of size-dependent microencapsulation (100–600 μm) and macroencapsulation (>1000 μm). (c) Analysing autoimmune disease treatments using various cancer stem cell types with neurodegenerative diseases. Reproduced with permission from Ref. [280], Copyright 2023, ACS.

Fig. 23

(A) Schematic diagram of the biomaterial capsule used to treat the bone regeneration of the animal model. Reproduced with permission from Ref. [281], Copyright 2025 Wiley-VCH. (B) Evaluation of bone regeneration capability using MSC-encapsulated alginate microgels in vivo study of 2D and 3D reconstructed micro-CT images of the tibial medullary cavity after 2 and 4 weeks post-implantation. Green regions indicate newly formed bone tissue cavity. Reproduced with permission from Ref. [245], Copyright 2020 Elsevier. (C) Micro-CT reconstruction images illustrating bone healing facilitated by the combined use of capsules and stem cells (a). Histological sections stained with H&E (b&c), and quantitative analysis of bone volume/total volume (BV/TV) and bone mineral density (BMD) across different groups: control, capsule, and capsule-BMSC (d&e). Reproduced from Ref. [274], Copyright 2022 Nano-Micro Letters. (D) Osteogenic protein expression analysis: (a) Representative immunofluorescence staining showing DAPI, DAPI/OPN, DAPI/OCN, and merged images for control, capsule, and capsule-BMSC groups. (b&c) Quantification of the relative OPN and OCN expression ratio of control, capsule, and capsule-BMSC groups. Reproduced from Ref. [274], Copyright 2022 Nano-Micro Letters.

Fig. 24

(a) A schematic illustration of a tissue engineering approach designed to accelerate wound healing using a microscale gel array patch encapsulating a defined SDF-1α gradient. Reproduced with permission from Ref. [282], Copyright 2023, Elsevier.(b) Incorporation of stem cells and polymer for enhanced skin regeneration. Reproduced with permission from Ref. [283], Copyright 2022, Elsevier. (c) Mechanism of skin regeneration facilitated by the trans-epithelial potential (TEP) during the wound healing process. Reproduced with permission from Ref. [284], Copyright 2021, Wiley-VCH.

Fig. 25

(A) Schematic diagram of the peripheral nervous system and different stages of nerve regeneration. Reproduced with permission from Ref. [286], Copyright 2024, Wiley-VCH. (B) Schwann cells dedifferentiate and proliferate to migrate to the injury site. Reproduced with permission from Ref. [286], Copyright 2024, Wiley-VCH. (C) Structural repair of peripheral nerves using graphene-based nanoscaffolds (GBN): The morphology of sciatic nerve sections was assessed using hematoxylin and eosin (HE) staining (a–d), toluidine blue (TB) staining (e–h), and transmission electron microscopy (i–t). Reproduced from Ref. [239], Copyright 2021, Nature. (D) Immunofluorescence staining of graphene-based nanoscaffolds of the regenerated nerve sections for CD34 (a–d) and VEGF (e–h), the fluorescence labelling of CD34 (green), VEGF (red), and nuclei (blue), HE staining of the gastrocnemius muscle (i–l) revealed the protective effects of GBN. Fluorescence labelling: CD34 (green), VEGF (red), and nuclei (blue). Immunostaining of the gastrocnemius muscle for fast myosin (m–p) and slow myosin (q–t). As represented, fast myosin (red), slow myosin (green), and nuclei (blue). These results indicated that relative expression levels of CD34 and VEGF in the sciatic nerves, along with fast and slow myosin in the gastrocnemius muscles, signify effective neurovascular regeneration and muscle preservation by GBN treatment. Scale bar 100 μm. Reproduced from Ref. [239], Copyright 2021, Nature.

Fig. 26

(a) Cell proliferation of 3D plot in MSCs encapsulated with PAA-RGD, PEG-RGD, and GelMA hydrogel was evaluated at 1, 3, and 7 days. Reproduced from Ref. [319], Copyright 2023, Elsevier (b) Quantitative analysis of MSCs encapsulated with PAA-RGD, PEG-RGD, and GelMA hydrogel as determined by the CCK-8 assay. Reproduced from Ref. [319], Copyright 2023, Elsevier (c) Macroscopic appearance of osteochondral tissue regeneration at weeks 6 and 12 for the treated groups: blank, PAA-RGD, PEG-RGD, and GelMA. Scale bar 5 mm. Reproduced from Ref. [319], Copyright 2023, Elsevier. (d) Bar representation graph of ICRS macroscopic assessment scores for blank, PAA-RGD, PEG-RGD, and GelMA at weeks 6 and 12. Reproduced from Ref. [319], Copyright 2023, Elsevier. (e–f) Shows the micro CT images of blank, PAA-RGD, PEG-RGD, and GelMA subchondral bone regeneration at 6 and 12 weeks. Scale bar 2.5 mm. Reproduced from Ref. [319], Copyright 2023, Elsevier. (g) Schematic diagram of a hydrogel implanted in C57/BL6 mice. (h) Histological and immunohistochemical analyses of explanted tissues after 14 days, including H&E, Masson's trichrome staining with brown arrows representing positive cells, while cell nuclei appear blue with hematoxylin. Scale bars: 1 mm and 200 μm. Reproduced from Ref. [319], Copyright 2023, Elsevier. (i) Immunohistochemical staining showed anti-inflammatory CD206⁺M2 macrophage and pro-inflammatory CD86⁺M1 macrophage responses. Reproduced from Ref. [319], Copyright 2023, Elsevier. (j–k) Quantitative analysis of macrophage polarization measured by qRT-PCR, the mRNA expression levels of M2-associated genes (IL-10, Arg-1) and M1-associated genes (IL-1β, iNOS) were measured in RAW 264.7 cells cultured with blank, PAA-RGD, PEG-RGD, and GelMA hydrogels for 3 and 7 days. Data are expressed as mean ± S.D. (n ≥ 3). Two-way ANOVA determined the statistical significance of all the quantitative images with Tukey's post hoc test. ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001. Reproduced from Ref. [319], Copyright 2023, Elsevier.