Umbilical Cord Mesenchymal Stromal Cells for Cartilage Regeneration Applications

Chondropathies are increasing worldwide, but effective treatments are currently lacking. Mesenchymal stromal cell (MSCs) transplantation represents a promising approach to counteract the degenerative and inflammatory environment characterizing those pathologies, such as osteoarthritis (OA) and rheumatoid arthritis (RA). Umbilical cord- (UC-) MSCs gained increasing interest due to their multilineage differentiation potential, immunomodulatory, and anti-inflammatory properties as well as higher proliferation rates, abundant supply along with no risks for the donor compared to adult MSCs. In addition, UC-MSCs are physiologically adapted to survive in an ischemic and nutrient-poor environment as well as to produce an extracellular matrix (ECM) similar to that of the cartilage. All these characteristics make UC-MSCs a pivotal source for a stem cell-based treatment of chondropathies. In this review, the regenerative potential of UC-MSCs for the treatment of cartilage diseases will be discussed focusing on in vitro, in vivo, and clinical studies.

Bioengineering Bone Tissue with 3D Printed Scaffolds in the Presence of Oligostilbenes

Diseases determining bone tissue loss have a high impact on people of any age. Bone healing can be improved using a therapeutic approach based on tissue engineering. Scientific research is demonstrating that among bone regeneration techniques, interesting results, in filling of bone lesions and dehiscence have been obtained using adult mesenchymal stem cells (MSCs) integrated with biocompatible scaffolds. The geometry of the scaffold has critical effects on cell adhesion, proliferation and differentiation. Many cytokines and compounds have been demonstrated to be effective in promoting MSCs osteogenic differentiation. Oligostilbenes, such as Resveratrol (Res) and Polydatin (Pol), can increase MSCs osteoblastic features. 3D printing is an excellent technique to create scaffolds customized for the lesion and thus optimized for the patient. In this work we analyze osteoblastic features of adult MSCs integrated with 3D-printed polycarbonate scaffolds differentiated in the presence of oligostilbenes.

The spatiotemporal expression patterns of MSC-associated markers contribute to the identification of progenitor subpopulations in developing limbs

During limb development, skeletal tissues differentiate from their progenitor cells in an orchestrated manner. Mesenchymal stromal cells (MSCs), which are considered to be adult undifferentiated/progenitor cells, have traditionally been identified by the expression of MSC-associated markers (MSC-am) and their differentiation capacities. However, although MSCs have been isolated from bone marrow and a variety of adult tissues, their developmental origin is poorly understood. Remarkably, adult MSCs share similar differentiation characteristics with limb progenitors. Here, we determined the expression patterns of common MSC-am throughout mouse hindlimb development. Our results demonstrate that MSC-am expression is not restricted to undifferentiated cells in vivo. Results from the analysis of MSC-am spatiotemporal expression in the embryonic hindlimb allowed us to propose five subpopulations which represent all limb tissues that potentially correspond to progenitor cells for each lineage. This work contributes to the understanding of MSC-am expression dynamics throughout development and underlines the importance of considering their expression patterns in future MSC studies of the limb.

Exosome-Derived miR21/SMAD7 Derived from Donor Osteoporosis Mesenchymal Stem Cells Inhibits Osteogenic Differentiation of Reconstituted Hosts

Exogenous bone marrow mesenchymal stem cells (MSCs) can regulate osteogenic differentiation. MicroRNA-21 has been shown to target SMAD7. This study explored the mechanism by which miR-21/SMAD7 inhibits osteogenic differentiation from exosomes secreted by osteoporosis patients-derived MSCs. Exosomes were obtained from MSCs and miR-21 expression was detected. Normal MSCs were treated with exosomes secreted by MSCs from different sources for osteogenic differentiation followed by detection of ALP, Bglap and Runx2 level and ALP activity. Normal MSCs were divided into three groups, which were treated with exosomes from normal adult MSCs, osteoporosis patients-derived MSCs and osteoporosis patients-derived MSCs + SMAD7 overexpression followed by analysis of the mRNA expression of ALP, Bglap and Runx2 by qRT-PCR and ALP activity. miR-21 expression in exosomes from osteoporosis patients-derived MSCs was significantly higher than that from normal adults MSCs. After treatment with exosomes from osteoporosis patients-derived MSCs, Runx2 expression and ALP activity was significantly decreased. SMAD7 expression in osteoporosis patients was significantly lower than that in normal adults. The expression of ALP, Bglap and Runx2 is significantly decreased after overexpression of SMAD7. SMAD7 is a target gene of miR-21 and plays a role in inhibiting osteogenic differentiation induced by exosomes from osteoporosis-derived MSCs.

Current Strategies to Enhance Adipose Stem Cell Function: An Update

Mesenchymal stem cells (MSCs) emerged as a promising therapeutic tool targeting a variety of inflammatory disorders due to their multiple remarkable properties, such as superior immunomodulatory function and tissue-regenerative capacity. Although bone marrow (BM) is a dominant source for adult MSCs, increasing evidence suggests that adipose tissue-derived stem cells (ASCs), which can be easily obtained at a relatively high yield, have potent therapeutic advantages comparable with BM-MSCs. Despite its outstanding benefits in pre-clinical settings, the practical efficacy of ASCs remains controversial since clinical trials with ASC application often resulted in unsatisfactory outcomes. To overcome this challenge, scientists established several strategies to generate highly functional ASCs beyond the naïve cells, including (1) pre-conditioning of ASCs with various stimulants such as inflammatory agents, (2) genetic manipulation of ASCs and (3) modification of culture conditions with three-dimensional (3D) aggregate formation and hypoxic culture. Also, exosomes and other extracellular vesicles secreted from ASCs can be applied directly to recapitulate the beneficial performance of ASCs. This review summarizes the current strategies to improve the therapeutic features of ASCs for successful clinical implementation.

Extracellular vesicles mediate improved functional outcomes in engineered cartilage produced from MSC/chondrocyte cocultures

Several recent studies have demonstrated that coculture of chondrocytes (CHs) with bone marrow-derived mesenchymal stem cells (MSCs) improves their chondrogenesis. This implies that intercellular communication dictates fate decisions in recipient cells and/or reprograms their metabolic state to support a differentiated function. While this coculture phenomenon is compelling, the differential chondroinductivity of zonal CHs on MSC cocultures, the nature of the molecular cargo, and their transport mechanisms remains undetermined. Here, we demonstrate that juvenile CHs in coculture with adult MSCs promote functional differentiation and improved matrix production. We further demonstrate that close proximity between the two cell types is a prerequisite for this response and that the outcome of this interaction improves viability, chondrogenesis, matrix formation, and homeostasis in the recipient MSCs. Furthermore, we visualized the transfer of intracellular contents from CHs to nearby MSCs and showed that inhibition of extracellular vesicle (EV) transfer blocks the synergistic effect of coculture, identifying EVs as the primary mode of communication in these cocultures. These findings will forward the development of therapeutic agents and more effective delivery systems to promote cartilage repair.

A Subset of Monocytic Cells Derived From Human Embryonic Stem Cells Can Give Rise to Mesenchymal Stromal Cells,

Abstract 3416 The relationship between monocytes and mesenchymal stromal cells remains a controversial issue. During embryonic development, the two cell types emerge early and share a large pattern of tissue expression. Using human embryonic stem cells (hES), we recently reported that embryonic monocytes/macrophages were endowed mainly with anti-inflammatory and remodeling functions. Here, we show that a subset of embryonic monocytic cells can give rise to stromal cells. Mesoderm and hematopoietic specification of hES were achieved from embryoid bodies in Iscove's Modified Dulbecco's medium (IMDM) supplemented with 15% fetal bovine serum (FBS) in presence of Bone Morphogenetic Protein 4 (BMP-4, 10 ng/ml) and Vascular Endothelial Growth Factor (VEGF, 5 ng/ml), followed by fetal liver tyrosine kinase 3 ligand (FLT3-ligand, 10 ng/ml), stem cell factor (SCF, 50 ng/ml), interleukin-3 (IL-3, 100 U/ml) and thrombopoietin (TPO, 10 ng/ml). Between day 14–21 of culture, CD45+14+ cells were sorted, cultured for 4 days in presence of Monocyte-Colony Stimulating Factor (M-CSF, 50 ng/ml), Granulocyte-Macrophage CSF (GM-CSF, 20 ng/ml) and IL-3, and subsequently seeded on fibronectin. After culture in Endothelial Cell Growth Medium supplemented with Endothelial GF (EGF), VEGF (25 ng/ml) and bFibroblast GF (bFGF) (1 ng/ml) for 14 days, clones of adherent cells with typical fibroblast-like morphology emerged at a frequency of 2/104 plated embryonic monocytic cells. In order to eliminate contaminating stromal cells before seeding on fibronectin, CD34low43+ hematopoietic cells were sorted at day 10 and CD45+14+ cells were sorted 7 days later. These cells were cultured with the previously described growth factors, but in serum free medium that does not support stromal cell proliferation. In these conditions, we observed that stromal cell developed from CD45+CD14+ embryonic monocytes. These EM-SCs shared several phenotypic and functional characteristics with adult mesenchymal stem cells (MSCs). They could be expanded in vitro in complete alpha–modified Eagle's medium (MEMa) supplemented with 10% FBS, by successive cycles of dissociation. At a density of 500 and 1000 per cm2, EM-SCs formed small colonies of CFU-F. EM-SCs did not express the hematopoietic surface markers CD14 and CD45, nor the endothelial markers CD31 and KDR, and strongly expressed CD105, CD73, CD13 and CD90. In contrast with adult MSCs, they expressed CD133 and low levels of CD34. EM-SCs could not elicit a proliferative response in the presence of allogeneic lymphocytes, and exhibited a suppressive effect on T-cell proliferation in mixed lymphocyte reaction. Under appropriate conditions, EM-SCs displayed osteogenic, chondrogenic and adipogenic differentiation. They could also adopt a smooth muscle cell but not an endothelial or a cardiac phenotype. Compared to adult MSCs, EM-SCs did not expressed telomerase reverse transcriptase, but demonstrated longer telomeres and enhanced expression of genes encoding growth factors, adhesion proteins, tissue degrading enzymes, and anti-inflammatory chemokines. EM-SCs also secreted high amounts of proteins involved in tissue remodeling and angiogenesis. Thus, a rare subset of embryonic monocytic cells can give rise to a population of stromal cells with high immunosuppressive and remodeling functions. A large body of evidence shows that macrophages and stromal cells are involved in tumor development. It remains to be explored whether stromal cells with remodelling potential could derive from tumor-infiltrating macrophages as it can derive from embryonic macrophages. hES cells offer a valuable experimental model for in vitro studies of these differentiation pathways. Disclosures: No relevant conflicts of interest to declare.