Fig. 3: Preparation and characterization of the mECM hydrogels, mECM + PM composites, and the release behavior of mECM@IL4 + PM@IGF1.

A Schematic diagram of mECM + PM composite preparation. B Stereomicroscopy, H&E, Masson’s trichrome, and DAPI staining of porcine skeletal muscle before and after decellularization. C Gel-forming properties of the 3% mECM hydrogel. D SEM images showing the structure and composition on the surfaces and cross-sections of 3% mECM and composite. Red and light blue dashed box: high magnification images; red dashed circle: microspheres; orange dashed box: central region of microsphere; purple dashed box: junction region of microspheres and mECM; white dashed line: junction of microspheres and mECM. E Stereomicroscopic images of the mECM hydrogel and composite, and fluorescent 3D images of rhodamine-labeled microspheres (red) and FITC-labeled mECM (green) composites. F Quantitative analysis of DAPI staining in Fig. 3B. Data are presented as mean ± SD (n = 3 independent samples, 5 random fields per sample). ****P < 0.0001, t test, two-tailed. G DNA quantitative analysis before and after decellularization. Data are presented as mean ± SD (n = 3 independent samples). ***P < 0.001, t test, two-tailed. H Detection of α-galactosidase before and after decellularization. Data are presented as mean ± SD (n = 3 independent samples). ****P < 0.0001, t test, two-tailed. I, J Rheological tests of the 3% mECM hydrogel and composite. K Gel-forming property. L The initial elastic modulus (G’) of 3% mECM hydrogels and the mECM + PM composites. Data are presented as mean ± SD (n = 3 independent samples). M, N Release profiles of IL-4 and IGF-1 in the mECM@IL4 + PM@IGF1 composites. Data are presented as mean ± SD (n = 2 independent samples). For (D, E), the experiment was repeated three times independently.