Indoleamine 2,3-Dioxygenase Is Dispensable for The Immunomodulatory Function of Stem Cells from Human Exfoliated Deciduous Teeth

Time- and Concentration-Dependent Effects of the Stem Cells Derived from Human Exfoliated Deciduous Teeth on Osteosarcoma Cells

Background

Stem cells have been proposed to be one of the potent sources for treatment applications. Among diverse types of stem cells, stem cells derived from human exfoliated deciduous teeth (SHEDs) are known as the immature stem cell population, which are easily isolated, fast, and without ethical implications. SHEDs could induce pluripotent stem cells and show differentiation in chondrocytes, adipocytes, osteoblasts, neural cells, hepatocytes, myocytes, odontoblasts, and skin cells.

Materials and Methods

In the current study, we investigated the effects of SHED on osteosarcoma cells (Saos-II) following 3 and 5 days indirect coculture.

Results

Our results showed that indirect coculture of SHED with Saos-II cells could promote or inhibit Saos-II cells' growth in a concentration (the number of SHED vs. Saos-II cells) and time (days of indirect co-culture) dependent manner.

Conclusion

Our findings suggested that, indirectly, SHED co-culture with the Soas-II cells might functions as a tumor suppressor where a higher number of SHEDs are used in the culture in comparison with the one cultured in the absence of/or fewer SHED incubation.

Multi-lineage differentiation and clinical application of stem cells from exfoliated deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHED) have now been considered one of the most promising sources of stem cells for tissue engineering and stem cell therapies due to their stemness and potential to differentiate into other cell lines. The high proliferation rate, the differentiation capacity, the easy access and less ethical concerns make SHED a brilliant solution for many diseases. The purpose of this review is to describe current knowledge of SHED's capability of differentiation, applications and immune status and to draw attention to further research on the mechanism and the dependability of stem cell therapy with SHED.

Combination therapies enhance immunoregulatory properties of MIAMI cells

Background

Mesenchymal stromal cells (MSCs), adult stromal cells most commonly isolated from bone marrow (BM), are being increasingly utilized in various therapeutic applications including tissue repair via immunomodulation, which is recognized as one of their most relevant mechanism of action. The promise of MSC-based therapies is somewhat hindered by their apparent modest clinical benefits, highlighting the need for approaches that would increase the efficacy of such therapies. Manipulation of cellular stress-response mechanism(s) such as autophagy, a catabolic stress-response mechanism, with small molecules prior to or during MSC injection could improve MSCs’ therapeutic efficacy. Unfortunately, limited information exists on how manipulation of autophagy affects MSCs’ response to inflammation and subsequent immunoregulatory properties.

Methods

In this study, we exposed BM-MSC precursor cells, “marrow-isolated adult multilineage inducible” (MIAMI) cells, to autophagy modulators tamoxifen (TX) or chloroquine (CQ), together with IFN-γ. Exposed cells then underwent RNA sequencing (RNAseq) to determine the effects of TX or CQ co-treatments on cellular response to IFN-γ at a molecular level. Furthermore, we evaluated their immunoregulatory capacity using activated CD4+ T cells by analyzing T cell activation marker CD25 and the percentage of proliferating T cells after co-culturing the cells with MIAMI cells treated or not with TX or CQ.

Results

RNAseq data indicate that the co-treatments alter both mRNA and protein levels of key genes responsible for MSCs’ immune-regulatory properties. Interestingly, TX and CQ also altered some of the microRNAs targeting such key genes. In addition, while IFN-γ treatment alone increased the surface expression of PD-L1 and secretion of IDO, this increase was further enhanced with TX. An improvement in MIAMI cells’ ability to decrease the activation and proliferation of T cells was also observed with TX, and to a lesser extent, CQ co-treatments.

Conclusion

Altogether, this work suggests that both TX and CQ have a potential to enhance MIAMI cells’ immunoregulatory properties. However, this enhancement is more pronounced with TX co-treatment.

Mesenchymal Stem/Stromal Cells Derived from Dental Tissues: A Comparative In Vitro Evaluation of Their Immunoregulatory Properties Against T cells

Bone marrow mesenchymal stem/stromal cells (BM-MSCs) have immunoregulatory properties and have been used as immune regulators for the treatment of graft-versus-host disease (GVHD). Human dental tissue mesenchymal stem cells (DT-MSCs) constitute an attractive alternative to BM-MSCs for potential clinical applications because of their accessibility and easy preparation. The aim of this in vitro study was to compare MSCs from dental pulp (DP-MSCs), gingival tissue (G-MSCs), and periodontal ligament (PDL-MSCs) in terms of their immunosuppressive properties against lymphoid cell populations enriched for CD3⁺ T cells to determine which MSCs would be the most appropriate for in vivo immunoregulatory applications. BM-MSCs were included as the gold standard. Our results demonstrated, in vitro, that MSCs from DP, G, and PDL showed immunoregulatory properties similar to those from BM, in terms of the cellular proliferation inhibition of both CD4⁺- and CD8⁺-activated T-cells. This reduced proliferation in cell co-cultures correlated with the production of interferon-γ and tumor necrosis factor alpha (TNF-α) and the upregulation of programmed death ligand 1 (PD-L1) in MSCs and cytotoxic T-cell-associated Ag-4 (CTLA-4) in T-cells and increased interleukin-10 and prostaglandin E₂ production. Interestingly, we observed differences in the production of cytokines and surface and secreted molecules that may participate in T-cell immunosuppression in co-cultures in the presence of DT-MSCs compared with BM-MSCs. Importantly, MSCs from four sources favored the generation of T-cell subsets displaying the regulatory phenotypes CD4⁺CD25⁺Foxp3⁺ and CD4⁺CD25⁺CTLA-4⁺. Our results in vitro indicate that, in addition to BM-MSCs, MSCs from all of the dental sources analyzed in this study might be candidates for future therapeutic applications.