Mesenchymal stem cells and acellular products attenuate murine induced colitis

Abstract

Background: Mesenchymal stem cells (MSCs) are a well-established immunomodulatory agent which can also promote tissue repair and regeneration. Recent studies have demonstrated MSCs as a novel therapeutic for inflammatory bowel disease (IBD), a chronic idiopathic inflammatory disorder of the gastrointestinal tract. However, the precise role of MSCs in regulating immune responses is controversial, and its significance in the pathogenesis remains IBD undefined. In addition, MSCs' acellular product, extracellular vesicles (EVs), may also play an important role in the armamentarium of therapeutics, but how EVs compare to MSCs remains unknown due to the lack of side-by-side comparative investigation. We herein compared MSCs and MSC-derived EVs for the treatment of IBD using a DSS-induced colitis model.

Methods: A DSS-induced colitis model was used. At day 4, mice received adipose-derived MSCs, MSC-derived EVs, or placebo. Weight loss, stool consistency, and hematochezia was charted. At day 8, murine colons were harvested, histologic analysis performed, and serum/tissue cytokine analysis conducted.

Results: MSCs and EVs demonstrated equivalent immunosuppressive function in DSS-treated mice through decreased colonic lymphocyte infiltration and attenuated disease severity after both MSC and EV treatment. Furthermore, both MSCs and EVs have an equivalent ability to inhibit inflammation in the DSS colitis model by inhibiting JAK, JNK 1/2, and STAT3 signaling.

Conclusions: These results suggest that (i) both MSCs and EVs are effective therapeutic candidates for a DSS-induced mouse colitis model, (ii) MSCs and EVs have similar immunosuppressive and anti-inflammatory functions, and (iii) EVs may present a novel future therapeutic for the treatment of IBD.

Keywords: Extracellular vesicles; Inflammatory bowel disease; Mesenchymal stem cells; Murine colitis model; Therapy.

Fig. 1

MSCs and EVs protected mice from DSS-induced colitis. a Clinical body weight scores of the PBS/MSC/EV-treated mice. Combined results from two experiments. n = 9. *p < 0.05. b The colon length of DSS-induced colitis groups treated by PBS/MSCs/EVs after sacrifice. The colon length of all PBS mice was significantly shorter than that of MSC/EV-treated groups. c The pictures of mouse colons, dissected from the cecum to the anus. Data are represented as mean ± SEM, *p < 0.05

Fig. 2

Local delivery of MSCs/EVs into mouse by i.p. injection. a, b MSCs. c, d EVs. For each mouse, CFSE-labeled MSCs or EVs were injected into the peritoneal cavity. At sacrifice, colon cryosections were prepared to examine the distribution of the injected MSCs/EVs (green) under a fluorescence microscope at original magnifications × 40 (a, c) and × 200 (b, d) with DAPI (blue). Arrows highlighted the CFSE-labeled MSCs/EVs

Fig. 3

Representative histopathologic image findings of the colonic mucosa (H&E). Mucosa of the PBS control group (a), MSCs (b), and EVs (c); arrows mark the infiltration of inflammatory cells and nearly total loss of crypts at colonic mucosa of the PBS group. Mice had markedly reduced leukocyte infiltration in MSC and EV groups as assessed by H&E staining (magnification: upper, × 100; arrows shown at lower, × 200). d Histological damage score was calculated based on microscopic colonic epithelial damage and infiltration of inflammatory cells, and the microscopic damage score of the PBS group was significantly higher than that of MSC- and EV-treated groups. Data are represented as mean ± SEM, *p < 0.05

Fig. 4

Systemic cytokine production. Mouse serum cytokines were determined by ELISA, and the concentration of IL-6, IL-10, TNF-α, IFN-γ, IL-17, and IL-12 were shown as ng/ml. n = 9 in the PBS group, n = 7 in MSC/EV groups. Data are represented as mean ± SEM, *p < 0.05

Fig. 5

Local cytokine production. Mouse local produced cytokines were tested from protein lysate by ELISA. The colon local cytokines’ (IL-6, IL-10, TNF-α, IFN-γ, IL-17, and IL-12) concentrations were normalized to the starting initial protein concentration, represented as ng/ml/mg protein. n = 9 in the PBS group, n = 7 in MSC/EV groups. Data are represented as mean ± SEM, *p < 0.05

Fig. 6

a MSCs/EVs inhibited the expression of STAT3, JNK, JAK1, and JAK2 after treatment. b–e The results of western blots are measured by Image J. Graphs show the results relative to β-actin. Data are shown as means ± SEM from three independent experiments, *p < 0.05