Present status and perspectives of stem cell-based therapies for gastrointestinal diseases

Circulating hematopoietic stem cells and putative intestinal stem cells in coeliac disease

Background

The intestinal stem cells (ISC) modulation and the role of circulating hematopoietic stem cells (HSC) in coeliac disease (CD) are poorly understood. Our aim was to investigate the longitudinal modifications in peripheral blood HSC traffic and putative ISC density induced by gluten-free diet (GFD) in CD.

Methods

Thirty-one CD patients and 7 controls were enrolled. Circulating CD133⁺ and CD34⁺ HSC were measured by flow cytometry, at enrolment and after 7 days and 1, 3, 6, 12, and 24 months of GFD. Endoscopy was performed at diagnosis and repeated at 6, 12, and 24 months following GFD. We used the Marsh-Oberhuber score to evaluate the histological severity of duodenal damage; immunohistochemistry was employed to measure the intraepithelial lymphoid infiltrate (IEL, CD3⁺ lymphoid cells) and the putative ISC compartment (CD133⁺ and Lgr5⁺ epithelial cells).

Results

At enrolment, circulating HSCs were significantly increased in CD patients and they further augmented during the first week of GFD, but progressively decreased afterwards. CD patients presented with villous atrophy, abundant IEL and rare ISC residing at the crypt base. Upon GFD, IEL progressively decreased, while ISC density increased, peaking at 12 months. After 24 months of GFD, all patients were asymptomatic and their duodenal mucosa was macroscopically and histologically normal.

Conclusions

In active CD patients, the ISC niche is depleted and there is an increased traffic of circulating HSC versus non-coeliac subjects. GFD induces a precocious mobilization of circulating HSC, which is followed by the expansion of the local ISC compartment, leading to mucosal healing and clinical remission.

Adoptive transfer of mesenchymal stromal cells accelerates intestinal epithelium recovery of irradiated mice in an interleukin-6-dependent manner

BACKGROUND AIMS

Apoptosis of radiosensitive cells in the bone marrow and gut is a serious, at times life-threatening, complication arising from radiation exposure.

METHODS

We investigated whether adoptive transfer of allogeneic bone marrow-derived mesenchymal stromal cells (MSC) could exert cytoprotective and life-sparing effects in a mouse model of sublethal total body irradiation (TBI).

RESULTS

We demonstrated that a single intraperitoneal injection of C57Bl/6 MSC given to major histocompatibility complex (MHC)-mismatched Balb/c mice within 24 h of sublethal TBI significantly reduced mortality in a dose-dependent manner. Histologic analysis and Ki67 immunostaining of jejunum sections collected 3 and 6 days post-TBI indicated that MSC protected the gastrointestinal epithelium from TBI-induced damage and significantly accelerated recovery of the gut by stimulating proliferation of the crypt cell pool. Using interleukin-6(-/-) (IL-6) MSC, we demonstrated that IL-6 expressed by MSC played a role in gastrointestinal epithelium regeneration.

CONCLUSIONS

Our results suggest that allogeneic MHC-mismatched MSC may be exploited to reduce gastrointestinal complications and mortality arising from ionizing radiation exposure.

[Preclinical experience in stem cell therapy for digestive tract diseases]

Adult stem cells are multipotent and self-renewing cells that contain several functions; i) migration and homing potential: stem cells can migrate to injured and inflamed tissues. ii) differentiation potential: stem cells which migrated to injured tissues can be differentiated into multiple cell types for repairing and regenerating the tissues. iii) immunomodulatory properties: stem cells, especially mesenchymal stem cells can suppress immune system such as inflammation. All those characteristics might be useful for the treatment of the digestive tract diseases which are complex and encompass a broad spectrum of different pathogenesis. Preclinical stem cell therapy showed some promising results, especially in liver failure, pancreatitis, sepsis, and inflammatory bowel disease. If we can understand more about the mechanism of stem cell action, stem cell therapy can become a promising alternative treatment for refractory digestive disease in the near future. In this review, we summarized current preclinical experiences in diseases of the digestive tract using stem cells. (Korean J Gastroenterol 2011;58:133-138).

Recent progress in understanding the molecular mechanisms underlying intestinal epithelial barrier function

Intestinal barrier dysfunction is related to the development of various clinical diseases. Recent probiotic studies have shown that the adhesive domain of surface layer proteins of lactobacillus can exert protective effects on intestinal epithelial cells. The role of tight junctions between intestinal epithelial cells in regulating intestinal epithelial barrier function has been established. Besides, intestinal alkaline phosphatase (IAP), protein phosphatase 2A (PP2A), and intraepithelial intestinal lymphocytes (IEL) are implicated in regulating intestinal epithelial barrier function. In addition, great attention has been paid to the association between intestinal stem cells and intestinal epithelial barrier function.