Stem cells for luminal, fistulizing, and perianal inflammatory bowel disease: a comprehensive updated review of the literature

Research progress on mesenchymal stem cells and their exosomes in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease with an unknown etiology. Clinically, it is characterized by localized or diffuse skin thickening and fibrosis. The pathogenesis of SSc includes microvascular injury, autoimmune-mediated inflammation, and fibroblast activation. These processes interact and contribute to the diverse clinicopathology and presentation of SSc. Given the limited effectiveness and substantial side effects of traditional treatments, the treatment strategy for SSc has several disadvantages. Mesenchymal stem cells (MSCs) are expected to serve as effective treatment options owing to their significant immunomodulatory, antifibrotic, and pro-angiogenic effects. Exosomes, secreted by MSCs via paracrine signaling, mirror the effect of MSCs as well as offer the benefit of targeted delivery, minimal immunogenicity, robust reparability, good safety and stability, and easy storage and transport. This enables them to circumvent the limitations of the MSCs. When using exosomes, it is crucial to consider preparation methods, quality standards, and suitable drug delivery systems, among other technical issues. Therefore, this review aims to summarize the latest research progress on MSCs and exosomes in SSc, offering novel ideas for treating SSc.

Adipose tissue-derived mesenchymal stem cells' acellular product extracellular vesicles as a potential therapy for Crohn's disease

The breakdown of gastrointestinal tract immune homeostasis leads to Crohn's disease (CD). Mesenchymal stem cells (MSCs) have demonstrated clinical efficacy in treating CD in clinical trials, but there is little known about the mechanism of healing. Considering the critical roles of macrophage polarization in CD and immunomodulatory properties of MSCs, we sought to decipher the interaction between adipose‐derived MSCs and macrophages, including their cytokine production, regulation of differentiation, and pro‐/anti‐inflammatory function. RNA extraction and next generation sequencing was performed in adipose tissue from healthy control patients' mesentery (n = 3) and CD mesentery (n = 3). Infiltrated macrophage activation in the CD mesentery was tested, MSCs and extracellular vesicles (EVs) were isolated to compare the regulation of macrophage differentiation, cytokines production, and self‐renewal capacities in vitro. CD patients' mesentery has increased M1 macrophage polarization and elevated activation. MSCs and their derived EVs, isolated from inflamed Crohn's mesentery, leads to a rapid differentiation of monocytes to a M1‐like polarized phenotype. Conversely, MSCs and their derived EVs from healthy, non‐Crohn's patients results in monocyte polarization into a M2 phenotype; this is seen regardless of the adipose source of MSCs (subcutaneous fat, omentum, normal mesentery). EVs derived from MSCs have the ability to regulate macrophage differentiation. Healthy MSCs and their associated EVs have the ability to drive monocytes to a M2 subset, effectively reversing an inflammatory phenotype. This mechanism supports why MSCs may be an effective therapeutic in CD and highlights EVs as a novel therapeutic for further exploration.

Drug delivery to the inflamed intestinal mucosa - targeting technologies and human cell culture models for better therapies of IBD

Current treatment strategies for inflammatory bowel disease (IBD) seek to alleviate the undesirable symptoms of the disorder. Despite the higher specificity of newer generation therapeutics, e.g. monoclonal antibodies, adverse effects still arise from their interference with non-specific systemic immune cascades. To circumvent such undesirable effects, both conventional and newer therapeutic options can benefit from various targeting strategies. Of course, both the development and the assessment of the efficiency of such targeted delivery systems necessitate the use of suitable in vivo and in vitro models representing relevant pathophysiological manifestations of the disorder. Accordingly, the current review seeks to provide a comprehensive discussion of the available preclinical models with emphasis on human in vitro models of IBD, along with their potentials and limitations. This is followed by an elaboration on the advancements in the field of biology- and nanotechnology-based targeted drug delivery systems and the potential rooms for improvement to facilitate their clinical translation.

Efficacy and safety of autologous adipose tissue-derived stem cell therapy for children with refractory Crohn's complex fistula: a Phase IV clinical study

Purpose

Autologous adipose tissue-derived stem cells (ASCs) have been proposed for patients with refractory Crohn disease, but research is lacking in pediatric patients. This Phase IV study evaluated the efficacy and safety of ASCs in children with refractory Crohn's fistulae.

Methods

Patients with a refractory Crohn's fistula who did not have conventional therapy for more than 3 months or with a recurrent complex Crohn's fistula were included. All patients were at least 14 years old. Patients with infection, poor condition, or active Crohn disease with a disease activity index of 450 and above were excluded. Five patients were treated with ASCs from 2014 to 2015 in Asan Medical Center. ASC administration was adjusted according to fistula size (1 mL per cm²). We evaluated the efficacy and safety 8 weeks after injection and followed patients for 6 months.

Results

Fistulae were healed in 4 patients by 8 weeks after ASC injection. Of these 4 patients, 1 had complete fistula closure and sustainability after 6 months. The other 3 with healing effects had less than 50% fistula closure by 6 months. None of these 4 patients have persistent fistulae. One patient had no healing effect, and seton ligation was performed 8 months after ASC injection. There were no adverse effects related to ASC administration.

Conclusion

ASC therapy is a simple and well-tolerated therapeutic option for children with refractory Crohn's complex fistulae. Complete closure was well-sustained. However, more data from a larger number of patients are needed.

The use of magnetic resonance imaging technique and 3D printing in order to develop a three-dimensional fistula model for patients with Crohn's disease: personalised medicine

Introduction

Preoperative evaluation of magnetic resonance (MR) images may not be sufficient for the precise planning of anal fistula surgery or for stem cell therapy. Three-dimensional (3D) printing allows one to obtain spatial structures in a 1 : 1 scale with unprecedented precision.

Aim

To combine magnetic resonance imaging (MRI) with 3D printing for more precise visualisation of perianal Crohn’s disease.

Material and methods

MRI at 1.5T and a 3D printer were used. DICOM (Digital imaging and communications in medicine) images were imported into 3D Slicer v.4.8.0. Firstly, anal fistula was modelled on the basis of axial images. Fistula locations, the anus and anal canal, were marked with different coloured markers. The last step was to mark the skin that was connected to the anus and contact areas of the fistula with the skin. The prepared models were then exported to an STL format file. The anal fistula model was printed using a 3D printer. The development of the model, including printing, took approximately 6 h.

Results and conclusions

The accessibility of a rotatable 3D model before surgery allows for a more precise detection of the location and the degree of perianal disease. Moreover, this may also lower the inter-observer bias connected with interpretation of complex MR imaging before planned surgery. Development of MRI image transfer to 3D printing and the decreasing cost of 3D printers suggests a promising future of this technology in medical applications.

Mesenchymal stem cells and acellular products attenuate murine induced colitis

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.