Hierarchy of mesenchymal stem cells: Comparison of multipotentmesenchymal stromal cells with fibroblast colony forming units

The organization of the compartment of mesenchymal stem cells is still obscure. Two types of human stromal precursor cells are known. Both of them are analyzed in in vitro system: mesenchymal multipotent stromal cells (MMSC) and fibroblast colony forming units (CFU-F). The aim of this study was to compare the main characteristics of MMSC and CFU-F derived from the bone marrow of 24 healthy donors. Growth and differentiation parameters, as well as relative expression levels of different genes were analyzed in MMSC and CFU-F. MMSC were cultivated for 5 passages. CFU-F concentration was determined for each bone marrow sample. The data obtained demonstrated the heterogeneity and hierarchical organization of both studied populations of stromal precursor cells-MMSC and CFU-F. These two types of stromal precursor cells turned to be different in most parameters studied. Altogether MMSC seemed to be more immature cells than CFU-F and took up the higher position in hierarchical tree of mesenchymal stem cells. The rate of differentiation and proliferative potential decreased with the donor’s age in both populations MMSC and CFU-F.

Immunophenotypic characteristics of multipotent mesenchymal stromal cells that affect the efficacy of their use in the prevention of acute graft vs host disease

BACKGROUND Multipotent mesenchymal stromal cells(MSCs)are widely used in the clinic due to their unique properties,namely,their ability to differentiate in all mesenchymal directions and their immunomodulatory activity.Healthy donor MSCs were used to prevent the development of acute graft vs host disease(GVHD)after allogeneic bone marrow transplantation(allo-BMT).The administration of MSCs to patients was not always effective.The MSCs obtained from different donors have individual characteristics.The differences between MSC samples may affect their clinical efficacy.AIM To study the differences between effective and ineffective MSCs.METHODS MSCs derived from the bone marrow of a hematopoietic stem cells donor were injected intravenously into allo-BMT recipients for GVHD prophylaxis at the moment of blood cell reconstitution.Aliquots of 52 MSC samples that were administered to patients were examined,and the same cells were cultured in the presence of peripheral blood mononuclear cells(PBMCs)from a third-party donor or treated with the pro-inflammatory cytokines IL-1β,IFN and TNF.Flow cytometry revealed the immunophenotype of the nontreated MSCs,the MSCs cocultured with PBMCs for 4 d and the MSCs exposed to cytokines.The proportions of CD25-,CD146-,CD69-,HLA-DR-and PD-1-positive CD4+and CD8+cells and the distribution of various effector and memory cell subpopulations in the PBMCs cocultured with the MSCs were also determined.RESULTS Differences in the immunophenotypes of effective and ineffective MSCs were observed.In the effective samples,the mean fluorescence intensity(MFI)of HLAABC,HLA-DR,CD105,and CD146 was significantly higher.After MSCs were treated with IFN or cocultured with PBMCs,the HLA-ABC,HLA-DR,CD90 and CD54 MFI showed a stronger increase in the effective MSCs,which indicated an increase in the immunomodulatory activity of these cells.When PBMCs were cocultured with effective MSCs,the proportions of CD4+and CD8+central memory cells significantly decreased,and the proportion of CD8+CD146+lymphocytes increased more than in the subpopulations of lymphocytes cocultured with MSC samples that were ineffective in the prevention of GVHD;in addition,the proportion of CD8+effector memory lymphocytes decreased in the PBMCs cocultured with the effective MSC samples but increased in the PBMCs cocultured with the ineffective MSC samples.The proportion of CD4+CD146+lymphocytes increased only when cocultured with the inefficient samples.CONCLUSION For the first time,differences were observed between MSC samples that were effective for GVHD prophylaxis and those that were ineffective.Thus,it was shown that the immunomodulatory activity of MSCs depends on the individual characteristics of the MSC population.

New insights for pelvic radiation disease treatment:Multipotent stromal cell is a promise mainstay treatment for the restoration of abdominopelvic severe chronic damages induced by radiotherapy

Radiotherapy may induce irreversible damage on healthy tissues surrounding the tumor. It has been reported that the majority of patients receiving pelvic radiation therapy show early or late tissue reactions of graded severity as radiotherapy affects not only the targeted tumor cells but also the surrounding healthy tissues. The late adverse effects of pelvic radiotherapy concern 5% to 10% of them, which could be life threatening. However, a clear medical consensus concerning the clinical management of such healthy tissue sequelae does not exist. Although no pharmacologic interventions have yet been proven to efficiently mitigate radiotherapy severe side effects, few preclinical researches show the potential of combined and sequential pharmacological treatments to prevent the onset of tissue damage. Our group has demonstrated in preclinical animal models that systemic mesenchymal stromal cell(MSC) injection is a promising approach for the medical management of gastrointestinal disorder after irradiation. We have shown that MSCs migrate to damaged tissues and restore gut functions after irradiation.We carefully studied side effects of stem cell injection for further application in patients. We have shown that clinical status of four patients suffering from severe pelvic side effects resulting from an over-dosage was improved following MSC injection in a compationnal situation.

Inflammatory priming of mesenchymal stem cells:Focus on growth factors enhancement

Multipotent mesenchymal stromal cells(MSCs)are actively involved in reparation and inflammation processes,providing damaged tissue reparation and suppressing immune cell responses in vivo.The effects are mostly due to the production of a wide range of paracrine factors,including growth factors and immunomodulatory mediators.To induce immunosuppressive activity,MSCs are primed by inflammatory cytokines,which results in an increased production of immunomodulatory molecules.However,stimulation of reparative properties is also necessary.This viewpoint manuscript highlights the possibilities of inflammatory priming to increase the production of growth factors by MSCs.

Multipotent mesenchymal stromal cells are fully permissive for human cytomegalovirus infection

Congenital human cytomegalovirus(HCMV) infection is a leading infectious cause of birth defects.Previous studies have reported birth defects with multiple organ maldevelopment in congenital HCMV-infected neonates. Multipotent mesenchymal stromal cells(MSCs) are a group of stem/progenitor cells that are multi-potent and can self-renew, and they play a vital role in multiorgan formation. Whether MSCs are susceptible to HCMV infection is unclear. In this study, MSCs were isolated from Wharton's jelly of the human umbilical cord and identified by their plastic adherence, surface marker pattern, and differentiation capacity. Then, the MSCs were infected with the HCMV Towne strain, and infection status was assessed via determination of viral entry,replication initiation, viral protein expression, and infectious virion release using western blotting,immunofluorescence assays, and plaque forming assays. The results indicate that the isolated MSCs were fully permissive for HCMV infection and provide a preliminary basis for understanding the pathogenesis of HCMV infection in non-nervous system diseases, including multi-organ malformation during fetal development.

外周血多潜能间充质基质细胞在骨组织工程中的应用进展

外周血来源的多潜能间充质基质细胞数量较少,它们表达骨髓来源的多潜能间充质基质细胞的大部分表面标记物,具有多样复杂的基因表达特征。虽然它们的起源和生理病理机制不清,但成人外周血间充质基质细胞的存在使其在组织工程领域备受争议和关注。本文就外周血来源的多潜能间充质基质细胞在骨组织工程中的应用作一综述。