Modified masson s trichrome stain kit

Standard Masson staining was performed using the Modified Masson’s Trichrome Stain Kit (G1345, Solarbio, Beijing, China) according to the manufacturer’s protocol. The positive area was quantified from several fields per sample with the Image-pro plus software program (v.6.0, Media Cybernetics, Rockville, MD, USA).

At 12-week post-transplantation, bilateral gastrocnemius muscles of rats were removed after electrophysiological evaluation and weighed immediately to determine the muscle weight ratio (injured side/normal side). The belly of gastrocnemius muscle was fixed in 4% paraformaldehyde for two hours, and then transverse paraffin sections with a thickness of 10 μm were performed and stained with modified Masson’s trichrome stain kit (G1345; Solarbio). At 20× magnification, six fields were randomly selected from each group, and the mean cross-sectional area of gastrocnemius fibers was measured using Image-Pro Plus software.

Mouse skin tissues fixed in 10% paraformaldehyde for 48 h and embedded in paraffin were sliced into 5 μm-thick sections. For H&E staining, the paraffin-embedded skin tissue sections were deparaffinized in xylene, rehydrated with ethanol at a reduced concentration, and stained using an H&E detection kit (Solarbio, China) and modified Masson’s trichrome stain kit (Solarbio, China) following the manufacturer’s instructions. Histological observation was then performed with an optical microscope.

Cell culture medium (MEM), fetal bovine serum (FBS), penicillin-streptomycin solution and trypsin-ethylenediaminetetraacetic acid (EDTA) were purchased from Gibco (Grand Island, NY, USA). The modified Masson’s trichrome stain kit and hematoxylin-eosin (H&E) were obtained from Solarbio Science & Technology Co., Ltd. (Beijing, China). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT, 98%), dexamethasone (DEX, ≥98%), and 1-chloro-2,4-dinitrobenzene (DNCB, 97%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Cetyltrimethylammonium bromide (CTAB), sodium hydroxide (NaOH), tetraethylorthosilicate (TEOS), dicyclohexylcarbodiimide (DCC), dimethyl formamide (DMF), nickel sulfate hexahydrate (NiSO₄·6H₂O) and dimethylaminopyridine (DMAP) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). Chlorogenic acid (CGA, CAS: 327-97-9, purity ≥ 98%) was purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China).

A total of 24 Kunming mice (female, 6–8 weeks) were housed in a specific pathogen-free animal care facility. Mice were allowed to adapt to the feeding environment for 7 days before the experiment. After the backs were depilated, the mice were randomly divided into four groups (n = 6): control, model (treated with UV), miR-Exo, and FELNVs groups. Mice in the control group were raised normally; the treatment groups were given treatment to the dorsal skin before each UVA irradiation. The miR-Exo group was treated with exosomes mimics (HA-PEI) wrapped with miR-CM1 before each UVA irradiation. The FELNVs group was treated with FELNVs from PL before each UVA irradiation. The model group was treated with placebo before each UVA irradiation. All mice were euthanized after 4 weeks. Dorsal skin tissues were collected and fixed in formalin. Following standard procedures, tissues were dehydrated and embedded in paraffin. Subsequently, 4 μm-thick sections were acquired for hematoxylin eosin (HE) staining, Fontana Masson staining, and immunohistochemical staining.
For HE and Masson staining, according to the manufacturer’s method, Modified HE Stain kit (Solarbio, China) and Modified Masson’s Trichrome Stain Kit (Solarbio, China) were used to evaluate pathological changes of the skin tissues.