Foreskin-derived mesenchymal stromal cells with aldehyde dehydrogenase activity: isolation and gene profiling

Functional single-cell analyses of mesenchymal stromal cell proliferation and differentiation using ALDH-activity and mitochondrial ROS content

BASKGROUND

Previous research has unveiled a stem cell-like transcriptome enrichment in the aldehyde dehydrogenase-expressing (ALDHhigh) mesenchymal stromal cell (MStroC) fraction. However, considering the heterogeneity of MStroCs, with only a fraction of them presenting bona fide stem cells (MSCs), the actual potency of ALDH as an MSC-specific selection marker remains an issue.

METHODS

To address this, the proliferative and differentiation potential of individual ALDHhigh and ALDHlow MStroCs incubated at low oxygen concentrations, estimated to mimic stem cell niches (0.1% O2), were assayed using single-cell clonal analysis, compared to standard conditions (20% O2).

RESULTS

We confirm that a high proliferative capacity and multi-potent MSCs are enriched in the ALDHhigh MStroC population, especially when cells are cultured at 0.1% O2. Measurements of reduced/oxidized glutathione and mitochondrial superoxide anions with MitoSoX (MSX) indicate that this advantage induced by low oxygen is related to a decrease in the oxidative and reactive oxygen species (ROS) levels in the stem cell metabolic setup. However, ALDH expression is neither specific nor exclusive to MSCs, as high proliferative capacity and multi-potent cells were also found in the ALDHlow fraction. Furthermore, single-cell assays performed after combined cell sorting based on ALDH and MSX showed that the MSXlow MStroC population is enriched in stem/progenitor cells in all conditions, irrespective of ALDH expression or culture oxygen concentration. Importantly, the ALDHhighMSXlow MStroC fraction exposed to 0.1% O2 was almost exclusively composed of genuine MSCs. In contrast, neither progenitors nor stem cells (with a complete absence of colony-forming ability) were detected in the MSXhigh fraction, which exclusively resides in the ALDHlow MStroC population.

CONCLUSION

Our study reveals that ALDH expression is not exclusively associated with MSCs. However, cell sorting using combined ALDH expression and ROS content can be utilized to exclude MStroCs lacking stem/progenitor cell properties.

Sorting Technology for Mesenchymal Stem Cells from a Single Tissue Source

Mesenchymal stem cells (MSCs) are adult stem cells that can be obtained, enriched and proliferated in vitro. They owned enormous potential in fields like regenerative medicine, tissue engineering and immunomodulation. However, though isolated from the same origin, MSCs are still essentially heterogeneous cell populations with different phenotypes and functions. This heterogeneity of MSCs significantly affects their therapeutic efficacy and brings obstacles to scientific research. Thus, reliable sorting technology which can isolate or purify MSC subpopulations with various potential and differentiation pathways is urgently needed. This review summarized principles, application status and clinical implications for these sorting methods, aiming at improving the understanding of MSC heterogeneity as well as providing fresh perspectives for subsequent clinical applications.

Gastric cancer and mesenchymal stem cell-derived exosomes: from pro-tumorigenic effects to anti-cancer vehicles

Gastric cancer (GC) is one of the most prevalent malignancies in the world, with a high mortality rate in both women and men. Conventional treatments, like chemotherapy, radiotherapy and surgery, are facing some drawbacks like acquired drug resistance and various side effects, leading to cancer recurrence and increased morbidity; thus, development of novel approaches in targeted therapy would be very beneficial. Exosomes, extracellular vesicles with a size distribution of sub-150 nm, interplay in physiological and pathophysiological cell-cell communications and can pave the way for targeted cancer therapy. Accumulating pieces of evidence have indicated that exosomes derived from mesenchymal stem cells (MSC-EXs) can act as a double-edged sword in some cancers. The purpose of this review is to assess the differences between stem cell therapy and exosome therapy. Moreover, our aim is to demonstrate how naïve MSCs transform into GC-MSCs in the tumor microenvironment. Additionally, the tumorigenic and anti-proliferation effects of MSC-EXs derived from different origins were investigated. Finally, we suggest potential modifications and combination options that involve utilizing MSC-EXs from the foreskin and umbilical cord as promising sources to enhance the efficacy of gastric cancer treatment. This approach is presented in contrast to bone marrow cells, which are more heterogeneous, age-related, and are also easily affected by the patient's circulation system.

Exosomes derived from human dermal fibroblasts protect against UVB‑induced skin photoaging

Exosomes are used as innovative treatment options for repairing skin defects, such as aging, atopic dermatitis and wounds. However, the effects of exosomes obtained from human foreskin fibroblasts BJ‑5ta (BJ‑5ta Exo) on ultraviolet B (UVB)‑mediated photoaging have not been previously reported, at least to the best of our knowledge. Therefore, the present study aimed to investigate the anti‑photoaging effects of BJ‑5ta Exo on UVB radiation in human skin fibroblasts and SKH‑1 hairless mice. The results revealed that BJ‑5ta Exo decreased the production of reactive oxygen species and inhibited the decrease in the expression levels of superoxide dismutase 1 and 2, glutathione peroxidase and catalase following UVB exposure. In addition, BJ‑5ta Exo attenuated the decrease in nuclear factor erythroid 2‑related factor 2 levels induced by UVB rays, indicating its scavenging activity against oxidative stress. Moreover, BJ‑5ta Exo inhibited the UVB‑induced increase in the levels of γH2AX, p53/21 and cleaved PARP, whereas it promoted DNA double‑strand break repair through radiation sensitive 52 and effectively activated the TGF‑β1/Smad pathway. BJ‑5ta Exo also protected against UVB‑induced senescence, as indicated by the downregulation in the levels of senescence‑associated β‑galactosidase and p16. In a mouse model of photoaging, BJ‑5ta Exo prevented the UVB‑induced increase in transepidermal water loss, wrinkle formation and MMP‑1 expression, while also suppressing the UVB‑mediated decrease in collagen type I and elastin levels in the dorsal skin. Overall, the findings of the present study suggest that BJ‑5ta Exo represent an effective anti‑photoaging agent, which can be used as a component in cosmetic products.

Role of Mesenchymal Stem Cells and Short Chain Fatty Acids in Allergy: A Prophylactic Therapy for Future

Allergic diseases are broadly classified as IgE-mediated type-I hypersensitivity immune reactions due to exposure to typically harmless substances known as allergens. These allergenic substances activate antigen presenting cells, which further triggers T-helper 2 cells immune response and class switch B-cells for synthesis of allergen-specific IgE, followed by classical activation of inflammatory mast cells and eosinophils, which releases preformed mediators involved in the cascade of allergic symptoms. However, the role of Mesenchymal stem cells (MSCs) in tissue repair ability and immunomodulation, makes them as an appropriate tool for treatment of various allergic diseases. Several clinical and preclinical studies show that MSCs could be a promising alternative therapy to allergic diseases. Further, short chain fatty acids, produced from gut microbes by breaking down complex fibre-rich foods, acts through G-coupled receptor mediated activation of MSCs, and their role as key players involved in amelioration of allergic inflammation needs further investigation. Therefore, there is a need for understating the role of SCFAs on the activation of MSCs, which might shed light on the development of new therapeutic regime in allergy treatment. In summary, this review focuses on the underlying of therapeutic role of MSCs in different allergic diseases and the prospects of SCFA and MSC therapy.

Hypoxia regulates adipose mesenchymal stem cells proliferation, migration, and nucleus pulposus-like differentiation by regulating endoplasmic reticulum stress via the HIF-1α pathway

OBJECTIVE

Hypoxia can promote stem cell proliferation and migration through HIF-1α. Hypoxia can regulate cellular endoplasmic reticulum (ER) stress. Some studies have reported the relationship among hypoxia, HIF-α, and ER stress, however, while little is known about HIF-α and ER stress in ADSCs under hypoxic conditions. The purpose of the study was to investigate the role and relationship of hypoxic conditions, HIF-1α and ER stress in regulating adipose mesenchymal stem cells (ADSCs) proliferation, migration, and NPC-like differentiation.

METHOD

ADSCs were pretreated with hypoxia, HIF-1α gene transfection, and HIF-1α gene silence. The ADSCs proliferation, migration, and NPC-like differentiation were assessed. The expression of HIF-1α in ADSCs was regulated; then, the changes of ER stress level in ADSCs were observed to investigate the relationship between ER stress and HIF-1α in ADSCs under hypoxic conditions.

RESULT

The cell proliferation and migration assay results show that hypoxia and HIF-1α overexpression can significantly increase the ADSCs proliferation and migration, while HIF-1α inhibition can significantly decrease the ADSCs proliferation and migration. The HIF-1α and co-cultured with NPCs played an important role in the directional differentiation of ADSCs into NPCs. The hypoxia-regulated ER stress in ADSCs through the HIF-1α pathway, thereby regulating the cellular state of ADSCs, was also observed.

CONCLUSION

Hypoxia and HIF-1α play important roles in proliferation, migration, and NPC-like differentiation of ADSCs. This study provides preliminary evidence that HIF-1α-regulated ER stress thus affects ADSCs proliferation, migration, and differentiation. Therefore, HIF-1α and ER may serve as key points to improve the efficacy of ADSCs in treating disc degeneration.

In Vitro Cellular and Molecular Interplay between Human Foreskin-Derived Mesenchymal Stromal/Stem Cells and the Th17 Cell Pathway

Foreskin, considered a biological waste material, has been shown to be a reservoir of therapeutic cells. The immunomodulatory properties of mesenchymal stromal/stem cells (MSCs) from the foreskin (FSK-MSCs) are being evaluated in cell-based therapy for degenerative, inflammatory and autoimmune disorders. Within the injured/inflamed tissue, proinflammatory lymphocytes such as IL-17-producing T helper cells (Th17) may interact with the stromal microenvironment, including MSCs. In this context, MSCs may encounter different levels of T cells as well as specific inflammatory signals. Uncovering the cellular and molecular changes during this interplay is central for developing an efficient and safe immunotherapeutic tool. To this end, an in vitro human model of cocultures of FSK-MSCs and T cells was established. These cocultures were performed at different cell ratios in the presence of an inflammatory setting. After confirming that FSK-MSCs respond to ISCT criteria by showing a typical phenotype and multilineage potential, we evaluated by flow cytometry the expression of Th17 cell markers IL-17A, IL23 receptor and RORγt within the lymphocyte population. We also measured 15 human Th17 pathway-related cytokines. Regardless of the T cell/MSC ratio, we observed a significant increase in IL-17A expression associated with an increase in IL-23 receptor expression. Furthermore, we observed substantial modulation of IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, INF-γ, sCD40, and TNF-α secretion. These findings suggest that FSK-MSCs are receptive to their environment and modulate the T cell response accordingly. The changes within the secretome of the stromal and immune environment are likely relevant for the therapeutic effect of MSCs. FSK-MSCs represent a valuable cellular product for immunotherapeutic purposes that needs to be further clarified and developed.

Insight into Hypoxia Stemness Control

Recently, the research on stemness and multilineage differentiation mechanisms has greatly increased its value due to the potential therapeutic impact of stem cell-based approaches. Stem cells modulate their self-renewing and differentiation capacities in response to endogenous and/or extrinsic factors that can control stem cell fate. One key factor controlling stem cell phenotype is oxygen (O₂). Several pieces of evidence demonstrated that the complexity of reproducing O₂ physiological tensions and gradients in culture is responsible for defective stem cell behavior in vitro and after transplantation. This evidence is still worsened by considering that stem cells are conventionally incubated under non-physiological air O₂ tension (21%). Therefore, the study of mechanisms and signaling activated at lower O₂ tension, such as those existing under native microenvironments (referred to as hypoxia), represent an effective strategy to define if O₂ is essential in preserving naïve stemness potential as well as in modulating their differentiation. Starting from this premise, the goal of the present review is to report the status of the art about the link existing between hypoxia and stemness providing insight into the factors/molecules involved, to design targeted strategies that, recapitulating naïve O₂ signals, enable towards the therapeutic use of stem cell for tissue engineering and regenerative medicine.

Mesenchymal Stromal Cell-Based Therapy: New Perspectives and Challenges

Stem cells have been the focus of intense research opening up new possibilities for the treatment of various diseases. Mesenchymal stromal cells (MSCs) are multipotent cells with relevant immunomodulatory properties and are thus considered as a promising new strategy for immune disease management. To enhance their efficiency, several issues related to both MSC biology and functions are needed to be identified and, most importantly, well clarified. The sources from which MSCs are isolated are diverse and might affect their properties. Both clinicians and scientists need to handle a phenotypic-characterized population of MSCs, particularly regarding their immunological profile. Moreover, it is now recognized that the tissue-reparative effects of MSCs are based on their immunomodulatory functions that are activated following a priming/licensing step. Thus, finding the best ways to pre-conditionate MSCs before their injection will strengthen their activity potential. Finally, soluble elements derived from MSC-secretome, including extracellular vesicles (EVs), have been proposed as a cell-free alternative tool for therapeutic medicine. Collectively, these features have to be considered and developed to ensure the efficiency and safety of MSC-based therapy. By participating to this Special Issue “Mesenchymal Stem/Stromal Cells in Immunity and Disease”, your valuable contribution will certainly enrich the content and discussion related to the thematic of MSCs.