Method for obtaining committed adult mesenchymal precursors from skin and lung tissue

Application of low-intensity pulsed therapeutic ultrasound on mesenchymal precursors does not affect their cell properties

Ultrasound is considered a safe and non-invasive tool in regenerative medicine and has been used in the clinic for more than twenty years for applications in bone healing after the approval of the Exogen device, also known as low-intensity pulsed ultrasound (LIPUS). Beyond its effects on bone health, LIPUS has also been investigated for wound healing of soft tissues, with positive results for various cell processes including cell proliferation, migration and angiogenesis. As LIPUS has the potential to treat chronic skin wounds, we sought to evaluate the effects produced by a conventional therapeutic ultrasound device at low intensities (also considered LIPUS) on the migration capacity of mouse and human skin mesenchymal precursors (s-MPs). Cells were stimulated for 3 days (20 minutes per day) using a traditional ultrasound device with the following parameters: 100 mW/cm2 with 20% duty cycle and frequency of 3 MHz. At the parameters used, ultrasound failed to affect s-MP proliferation, with no evident changes in morphology or cell groupings, and no changes at the cytoskeletal level. Further, the migration and invasion ability of s-MPs were unaffected by the ultrasound protocol, and no major changes were detected in the gene/protein expression of ROCK1, integrin β1, laminin β1, type I collagen and transforming growth factor β1. Finally, RNA-seq analysis revealed that only 10 genes were differentially expressed after ultrasound stimulation. Among them, 5 encode for small nuclear RNAs and 2 encode for proteins belonging to the nuclear pore complex. Considering the results overall, while the viability of s-MPs was not affected by ultrasound stimulation and no changes were detected in proliferation/migration, RNA-seq analysis would suggest that s-MPs do respond to ultrasound. The use of 100 mW/cm2 intensity or conventional therapeutic ultrasound devices might not be optimal for the stimulation the properties of cell populations. Future studies should investigate the potential application of ultrasound using variations of the tested parameters.

Immunomodulatory and Regenerative Effects of Mesenchymal Stem Cells and Extracellular Vesicles: Therapeutic Outlook for Inflammatory and Degenerative Diseases

Mesenchymal stem cells (MSCs) are non-hematopoietic, multipotent stem cells derived from mesoderm, which can be easily isolated from many sources such as bone marrow, umbilical cord or adipose tissue. MSCs provide support for hematopoietic stem cells and have an ability to differentiate into multiple cell lines. Moreover, they have proangiogenic, protective and immunomodulatory properties. MSCs have the capacity to modulate both innate and adaptive immune responses, which accompany many diseases, by inhibiting pro-inflammatory reactions and stimulating anti-inflammatory activity. Recent findings revealed that the positive effect of MSCs is at least partly associated with the production of extracellular vesicles (EVs). EVs are small membrane structures, containing proteins, lipids and nuclei acids, which take part in intra-cellular communication. Many studies indicate that EVs contain protective and pro-regenerative properties and can modulate an immune response that is activated in various diseases such as CNS diseases, myocardial infarction, liver injury, lung diseases, ulcerative colitis or kidney injury. Thus, EVs have similar functions as their cells of origin and since they do not carry the risk of cell transplantation, such as tumor formation or small vessel blockage, they can be considered a potential therapeutic tool for cell-free therapy.

BMPER is upregulated in obesity and seems to have a role in pericardial adipose stem cells

Pericardial adipose tissue (PAT), a visceral fat depot enveloping the heart, is an active endocrine organ and a source of free fatty acids and inflammatory cytokines. As in other fat adult tissues, PAT contains a population of adipose stem cells; however, whether these cells and/or their environment play a role in physiopathology is unknown. We analyzed several stem cell-related properties of pericardial adipose stem cells (PSCs) isolated from obese and ex-obese mice. We also performed RNA-sequencing to profile the transcriptional landscape of PSCs isolated from the different diet regimens. Finally, we tested whether these alterations impacted on the properties of cardiac mesoangioblasts isolated from the same mice. We found functional differences between PSCs depending on their source: specifically, PSCs from obese PSC (oPSC) and ex-obese PSC (dPSC) mice showed alterations in apoptosis and migratory capacity when compared with lean, control PSCs, with increased apoptosis in oPSCs and blunted migratory capacity in oPSCs and dPSCs. This was accompanied by different gene expression profiles across the cell types, where we identified some genes altered in obese conditions, such as BMP endothelial cell precursor-derived regulator (BMPER), an important regulator of BMP-related signaling pathways for endothelial cell function. The importance of BMPER in PSCs was confirmed by loss- and gain-of-function studies. Finally, we found an altered production of BMPER and some important chemokines in cardiac mesoangioblasts in obese conditions. Our findings point to BMPER as a potential new regulator of PSC function and suggest that its dysregulation could be associated with obesity and may impact on cardiac cells.

Long term explant culture for harvesting homogeneous population of human dental pulp stem cells

Dental pulp stem cells have emerged as a preferred source of mesenchymal stem cells, because of its easy availability and high stem cell content. Dental pulp is a specific fibrous tissue that contains heterogeneous populations of odontoblasts, fibroblasts, pericytes, progenitors, stem cells, leukocytes and neuronal cells. In this study, we propose sustained explant culture as a simple, economical and efficient process to isolate dental pulp stem cells from human Dental pulp Tissue. Historically explant cultures were used to get fibroblast cells from embryonic chick heart using plasma clot cultures. The subculture was performed by lifting mother explant (original explant) and grafting it in a new plasma clot. We modified this age old technique to suit the modern times. Here we demonstrate for the first time that the mother explant (E0) of human dental pulp tissue could be sub-cultured consecutively seven times (E7) without displacement. This technique is highly reproducible and permits growth and proliferation of dental pulp stem cells yielding an enriched homogeneous mesenchymal stem cells population in the first passage itself as revealed by surface marker expression. These dental pulp stem cells exhibit differentiation into adipogenic, chondrogenic and osteogenic lineage revealing their mesenchymal stem cell nature. We propose that dental pulp stem cells isolated by sustained explant culture are phenotypically and functionally comparable to those obtained by enzymatic method. It is a simple, inexpensive and gentle method, which may be preferred over the conventional techniques for obtaining stem cells from other tissue sources as well especially in cases of limited starting material.

Importance and regulation of adult stem cell migration

Cell migration is an essential process throughout the life of vertebrates, beginning during embryonic development and continuing throughout adulthood. Stem cells have an inherent ability to migrate, that is as important as their capacity for self‐renewal and differentiation, enabling them to maintain tissue homoeostasis and mediate repair and regeneration. Adult stem cells reside in specific tissue niches, where they remain in a quiescent state until called upon and activated by tissue environmental signals. Cell migration is a highly regulated process that involves the integration of intrinsic signals from the niche and extrinsic factors. Studies using three‐dimensional in vitro models have revealed the astonishing plasticity of cells in terms of the migration modes employed in response to changes in the microenvironment. These same properties can, however, be subverted during the development of some pathologies such as cancer. In this review, we describe the response of adult stem cells to migratory stimuli and the mechanisms by which they sense and transduce intracellular signals involved in migratory processes. Understanding the molecular events underlying migration may help develop therapeutic strategies for regenerative medicine and to treat diseases with a cell migration component.

New insight on obesity and adipose-derived stem cells using comprehensive metabolomics

Obesity affects the functional capability of adipose-derived stem cells (ASCs) and their effective use in regenerative medicine through mechanisms that are still poorly understood. In the present study we used a multiplatform [LC/MS, GC/MS and capillary electrophoresis/MS (CE/MS)], metabolomics, untargeted approach to investigate the metabolic alteration underlying the inequalities observed in obesity-derived ASCs. The metabolic fingerprint (metabolites within the cells) and footprint (metabolites secreted in the culture medium), from obesity- and non-obesity-derived ASCs of humans or mice, were characterized to provide valuable information. Metabolites associated with glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway and the polyol pathway were increased in the footprint of obesity-derived human ASCs, indicating alterations in carbohydrate metabolism, whereas, from the murine model, deep differences in lipid and amino acid catabolism were highlighted. Therefore, new insights on the ASCs' metabolome were provided that enhance our understanding of the processes underlying ASCs' stemness capacity and its relationship with obesity, in different cell models.

Comparison of TGF-β1 and NO production by mesenchymal stem cells isolated from murine lung and adipose tissues

CONTEXT

Mesenchymal stem cells (MSCs) are cell sources for tissues regeneration. By secretion of soluble factors including transforming growth factor-β (TGF-β1) and nitric oxide (NO), MSCs are also able to regulate the immune system. MSCs have been disclosed in lung and adipose tissues with insufficient comparison between the tissues.

OBJECTIVES

In this study, specific differentiation and the expression of surface antigens as well as TGF-β1 and NO productive levels were compared in murine lung-derived MSCs (LMSCs) and adipose tissue-derived MSCs (ADMSCs).

MATERIALS AND METHODS

MSCs were isolated from murine lung and adipose tissues and cultured. Both cell populations were characterized using multilineage potential and the expression of surface antigenic proteins, CD73, CD105, CD34, CD45, and CD11b. Finally, levels of TGF-β1 and NO were evaluated and compared in ADMSCs and LMSCs.

RESULTS

Expression of CD73 and CD105; lack of the expression of CD34, CD45, and CD11b markers; as well as adipocyte and osteocyte differentiations were detected in both adult stem cells. No significant difference was found in TGF-β1 and NO production between two stem cell populations.

CONCLUSION

Our data showed that LMSCs and ADMSCs have comparable phenotype and TGF-β1 and NO production.

Pérez L, San Martín N, Gálvez BG. Membrane Blebbing Is Required for Mesenchymal Precursor Migration

Mesenchymal precursors (MPs) present some advantageous features, such as differentiation and migration, which make them promising candidates for cell therapy. A better understanding of MP migration characteristics would aid the development of cell delivery protocols. Traditionally, cell migration is thought to occur only through the formation of lamellipodia. More recently, contractility-driven bleb formation has emerged as an alternative mechanism of motility. Here we report that MPs derived from different tissues present spontaneously dynamic cytoplasmic projections in sub-confluent culture, which appear as a combination of lamellipodia with blebs in the leading edge. Upon initial seeding, however, only bleb structures could be observed. Immunofluorescence revealed the presence of pERM, RhoA and F-actin during the blebbing process. Results from migration assays in the presence of blebbistatin, a myosin II inhibitor, showed that bleb formation correlated with migratory capacity, suggesting a functional role for blebs in migration. Bleb formation might be a useful mechanism to improve cell migration in cellular therapy protocols.

Obesity-driven alterations in adipose-derived stem cells are partially restored by weight loss

OBJECTIVE

The therapeutic potential of adipose-derived stem cells (ASCs) is reduced by various stress-inducing conditions that affect tissue homeostasis such as diabetes, aging, and obesity. Previous works have provided evidence of negative effects of obesity on ASC populations, but it is unclear whether this persists after a weight loss. This study evaluated whether weight loss can restore the attenuated properties found in ASCs derived from populations with obesity (oASCs).

METHODS

In vitro functional analyses were performed to investigate the possible recovery properties in mouse oASCs. Using ASCs isolated from subcutaneous tissue from formerly obese mice (dASCs) and control mice (cASCs), cell proliferation, viability, and some regenerative properties in these cells were analyzed compared with oASCs to evaluate the functional cell state.

RESULTS

Cell proliferation, viability, and some regenerative properties are strengthened in dASCs and cASCs compared with oASCs. Nevertheless, metabolic analysis reveals a mitochondrial load misbalance and function leading to impaired respiration in dASCs.

CONCLUSIONS

This study demonstrates that an initial obese environment triggers a detrimental state in ASCs that is not completely recovered after weight loss.

Altered metabolic and stemness capacity of adipose tissue-derived stem cells from obese mouse and human

Adipose stem cells (ASCs) are an appealing source of cells for therapeutic intervention; however, the environment from which ASCs are isolated may impact their usefulness. Using a range of functional assays, we have evaluated whether ASCs isolated from an obese environment are comparable to cells from non-obese adipose tissue. Results showed that ASCs isolated from obese tissue have a reduced proliferative ability and a loss of viability together with changes in telomerase activity and DNA telomere length, suggesting a decreased self-renewal capacity. Metabolic analysis demonstrated that mitochondrial content and function was impaired in obese-derived ASCs resulting in changes in favored oxidative substrates. These findings highlight the impact of obesity on adult stem properties. Hence, caution should be exercised when considering the source of ASCs for cellular therapies since their therapeutic potential may be impaired.