Suitability of human mesenchymal stem cells for gene therapy depends on the expansion medium

Great hope is set in the use of mesenchymal stem cells for gene therapy and regenerative medicine. Since the frequency of this subpopulation of stem cells in bone marrow is low, mesenchymal stem cells are expanded ex vivo and manipulated prior to experimental or clinical use. Different methods for isolation and expansion are available, but the particular effect on the stem cell character is unclear. While the isolation of mesenchymal stem cells by density centrifugation followed by selection of the plastic adherent fraction is frequently used, the composition of expansion media differs. Thus, in the present study we cultured mesenchymal stem cells isolated from five healthy young volunteers in three widely used expansion media and performed a detailed analysis of the effect on morphology, proliferation, clonogenicity, passaging, differentiation and senescence. By this way we clearly show that the type of expansion medium used determines the stem cell character and time of senescence which is critical for future gene therapeutic and regenerative approaches using mesenchymal stem cells.     

Control of stem cell fate by engineering their micro and nanoenvironment

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.     

A Combination of Culture Conditions and Gene Expression Analysis Can Be Used to Investigate and Predict hES Cell Differentiation Potential towards Male Gonadal Cells

Human embryonic stem cell differentiation towards various cell types belonging to ecto-, endo- and mesodermal cell lineages has been demonstrated, with high efficiency rates using standardized differentiation protocols. However, germ cell differentiation from human embryonic stem cells has been very inefficient so far. Even though the influence of various growth factors has been evaluated, the gene expression of different cell lines in relation to their differentiation potential has not yet been extensively examined. In this study, the potential of three male human embryonic stem cell lines to differentiate towards male gonadal cells was explored by analysing their gene expression profiles. The human embryonic stem cell lines were cultured for 14 days as monolayers on supporting human foreskin fibroblasts or as spheres in suspension, and were differentiated using BMP7, or spontaneous differentiation by omitting exogenous FGF2. TLDA analysis revealed that in the undifferentiated state, these cell lines have diverse mRNA profiles and exhibit significantly different potentials for differentiation towards the cell types present in the male gonads. This potential was associated with important factors directing the fate of the male primordial germ cells in vivo to form gonocytes, such as SOX17 or genes involved in the NODAL/ACTIVIN pathway, for example. Stimulation with BMP7 in suspension culture resulted in up-regulation of cytoplasmic SOX9 protein expression in all three lines. The observation that human embryonic stem cells differentiate towards germ and somatic cells after spontaneous and BMP7-induced stimulation in suspension emphasizes the important role of somatic cells in germ cell differentiation in vitro.     

Adipose stromal/stem cells in regenerative medicine:Potentials and limitations

This article presents the stem and progenitor cells from subcutaneous adipose tissue,briefly comparing them with their bone marrow counterparts,and discussing their potential for use in regenerative medicine.Subcutaneous adipose tissue differs from other mesenchymal stromal/stem cells(MSCs) sources in that it contains a pre-adipocyte population that dwells in the adventitia of robust blood vessels.Pre-adipocytes are present both in the stromal-vascular fraction(SVF;freshly isolated cells) and in the adherent fraction of adipose stromal/stem cells(ASCs;in vitro expanded cells),and have an active role on the chronic inflammation environment established in obesity,likely due their monocyticmacrophage lineage identity.The SVF and ASCs have been explored in cell therapy protocols with relative success,given their paracrine and immunomodulatory effects.Importantly,the widely explored multipotentiality of ASCs has direct application in bone,cartilage and adipose tissue engineering.The aim of this editorial is to reinforce the peculiarities of the stem and progenitor cells from subcutaneous adipose tissue,revealing the spheroids as a recently described biotechnological tool for cell therapy and tissue engineering.Innovative cell culture techniques,in particular 3 D scaffold-free cultures such as spheroids,are now available to increase the potential for regeneration and differentiation of mesenchymal lineages.Spheroids are being explored not only as a model for cell differentiation,but also as powerful 3 D cell culture tools to maintain the stemness and expand the regenerative and differentiation capacities of mesenchymal cell lineages.     

Regulation of stemness and stem cell niche of mesenchymal stem cells: Implications in tumorigenesis and metastasis

Human mesenchymal stem cells (MSCs) derived from adult tissues have been considered a candidate cell type for cell‐based tissue engineering and regenerative medicine. These multipotent cells have the ability to differentiate along several mesenchymal lineages and possibly along non‐mesenchymal lineages. MSCs possess considerable immunosuppressive properties that can influence the surrounding tissue positively during regeneration, but perhaps negatively towards the pathogenesis of cancer and metastasis. The balance between the naïve stem state and differentiation is highly dependent on the stem cell niche. Identification of stem cell niche components has helped to elucidate the mechanisms of stem cell maintenance and differentiation. Ultimately, the fate of stem cells is dictated by their microenvironment. In this review, we describe the identification and characterization of bone marrow‐derived MSCs, the properties of the bone marrow stem cell niche, and the possibility and likelihood of MSC involvement in cancer progression and metastasis. J. Cell. Physiol. 222: 268–277, 2010. © 2009 Wiley‐Liss, Inc.     

Variable expression of lineage regulators in differentiated stromal cells indicates distinct mechanisms of differentiation towards common cell fate

Mesenchymal stem cells (MSCs) possess a multi-lineage differentiation capacity that makes them important players in the field of regenerative medicine. MSC populations derived from different tissues or donors have been shown to exhibit variable gene expression patterns. Further, it is widely acknowledged that MSC isolates are heterogeneous mixtures of cells at different developmental stages. However, the heterogeneity of expression of lineage regulators has not been linked to differentiation potential of different MSC populations towards mesenchymal lineages. Here, we analyzed variation of expression of differentiation markers across whole population and between single differentiating cells of multipotent stromal cell populations derived from adipose tissue (AdMSCs) and skin (FBs) of seven donors. The results of the analyses show that all cell populations exhibit similar differentiation potential towards adipocyte, osteoblast and chondrocyte lineages despite tissue type- and donor-specific variations of expression of differentiation-associated genes. Further, we detected variable expression of lineage regulators in individual differentiating cells. Together, our data indicate that single cells of stromal cell populations could use distinct molecular mechanisms to reach a common cell fate.     

A feasibility study of an in vitro differentiation potential toward insulin-producing cells by dental tissue-derived mesenchymal stem cells

Dental tissue-derived mesenchymal stem cells have been proposed as an alternative source for mesenchymal stem cells. Here, we investigated the differentiation ability toward insulin producing cells (IPCs) of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs). These cells expressed mesenchymal stem cell surface markers and were able to differentiate toward osteogenic and adipogenic lineages. Upon 3 step-IPCs induction, hDPSCs exhibited more colony number than hPDLSCs. The mRNA upregulation of pancreatic endoderm/islet markers was noted. However, the significant increase was noted only for PDX-1, NGN-3, and INSULIN mRNA expression of hDPSCs. The hDPSCs-derived IPCs expressed PRO-INSULIN and released C-PEPTIDE upon glucose stimulation in dose-dependent manner. After IPCs induction, the Notch target, HES-1 and HEY-1, mRNA expression was markedly noted. Notch inhibition during the last induction step or throughout the protocol disturbed the ability of C-PEPTIDE release upon glucose stimulation. The results suggested that hDPSCs had better differentiation potential toward IPCs than hPDLSCs. In addition, the Notch signalling might involve in the differentiation regulation of hDPSCs into IPCs.     

Awakened by Cellular Stress: Isolation and Characterization of a Novel Population of Pluripotent Stem Cells Derived from Human Adipose Tissue

Advances in stem cell therapy face major clinical limitations, particularly challenged by low rates of post-transplant cell survival. Hostile host factors of the engraftment microenvironment such as hypoxia, nutrition deprivation, pro-inflammatory cytokines, and reactive oxygen species can each contribute to unwanted differentiation or apoptosis. In this report, we describe the isolation and characterization of a new population of adipose tissue (AT) derived pluripotent stem cells, termed Multilineage Differentiating Stress-Enduring (Muse) Cells, which are isolated using severe cellular stress conditions, including long-term exposure to the proteolytic enzyme collagenase, serum deprivation, low temperatures and hypoxia. Under these conditions, a highly purified population of Muse-AT cells is isolated without the utilization of cell sorting methods. Muse-AT cells grow in suspension as cell spheres reminiscent of embryonic stem cell clusters. Muse-AT cells are positive for the pluripotency markers SSEA3, TR-1-60, Oct3/4, Nanog and Sox2, and can spontaneously differentiate into mesenchymal, endodermal and ectodermal cell lineages with an efficiency of 23%, 20% and 22%, respectively. When using specific differentiation media, differentiation efficiency is greatly enhanced in Muse-AT cells (82% for mesenchymal, 75% for endodermal and 78% for ectodermal). When compared to adipose stem cells (ASCs), microarray data indicate a substantial up-regulation of Sox2, Oct3/4, and Rex1. Muse-ATs also exhibit gene expression patterns associated with the down-regulation of genes involved in cell death and survival, embryonic development, DNA replication and repair, cell cycle and potential factors related to oncogenecity. Gene expression analysis indicates that Muse-ATs and ASCs are mesenchymal in origin; however, Muse-ATs also express numerous lymphocytic and hematopoietic genes, such as CCR1 and CXCL2, encoding chemokine receptors and ligands involved in stem cell homing. Being highly resistant to severe cellular stress, Muse-AT cells have the potential to make a critical impact on the field of regenerative medicine and cell-based therapy.     

Notch signalling inhibits the adipogenic differentiation of single‐cell‐derived mesenchymal stem cell clones isolated from human adipose tissue

ADSCs (adipose‐derived mesenchymal stem cells) are candidate adult stem cells for regenerative medicine. Notch signalling participates in the differentiation of a heterogeneous ADSC population. We have isolated, human adipose tissue‐derived single‐cell clones using a cloning ring technique and characterized for their stem cell characteristics. The role of Notch signalling in the differentiation capacity of these adipose‐derived single‐cell‐clones has also been investigated. All 14 clones expressed embryonic and mesenchymal stem cell marker genes. These clones could differentiate into both osteogenic and adipogenic lineages. However, the differentiation potential of each clone was different. Low adipogenic clones had significantly higher mRNA expression levels of Notch 2, 3 and 4, Jagged1, as well as Delta1, compared with those of high adipogenic clones. In contrast, no changes in expression of Notch signalling component mRNA between low and high osteogenic clones was found. Notch receptor mRNA expression decreased with the adipogenic differentiation of both low and high adipogenic clones. The γ‐secretase inhibitor, DAPT (N‐[N‐(3,5‐difluorophenacetyl)‐l ‐alanyl]‐(S)‐phenylglycine t‐butyl ester), enhanced adipogenic differentiation. Correspondingly, cells seeded on a Notch ligand (Jagged1) bound surface showed lower intracellular lipid accumulation. These results were noted in both low and high adipogenic clones, indicating that Notch signalling inhibited the adipogenic differentiation of adipose ADSC clones, and could be used to identify an adipogenic susceptible subpopulation for soft‐tissue augmentation application.     

Generation of megakaryocytes and platelets from preadipocyte cell line 3T3-L1, but not the parent cell line 3T3, in vitro

Platelets are produced from megakaryocytes (MKs), although the pathway leading from stem cells to MK lineages are not yet fully understood. Recently, we reported to obtain abundant MKs and platelets from human subcutaneous adipose tissues. Adipose tissues contain various cell types, most of which are lineage cells from mesenchymal or adipocyte-derived stem cells, distinct from hematopoietic cells. To identify the cells responsible for the differentiation MK lineages in adipose tissues, this study examined whether the preadipocyte cell line 3T3-L1 and fibroblast cell line 3T3 differentiated into MK lineages in vitro. Cells were cultured in megakaryocyte lineage induction medium. By day 4, most of 3T3 cell-derived cells leaded to cell death. In contrast, 3T3-L1-derived cells on days 8 showed to have typical characterizations of MK lineages in analyses for specific marker, DNA ploidy, transmission electro micrograph. 3T3-L1-derived platelet-sized cells on day 12 could be stimulated by ADP and PAR4-activating peptide. This study clearly shows in vitro differentiation from 3T3-L1 cells, not from 3T3 cells, into MK lineages.     

Gangliosides are involved in neural differentiation of human dental pulp-derived stem cells

Human dental pulp-derived stem cells (hDPSCs) have been considered alternative sources of adult stem cells because of their potential to differentiate into multiple cell lineages. This study investigated the possible role of gangliosides in the neural differentiation of hDPSCs. When hDPSCs were cultured under neural differentiation conditions, expression of neural cell marker genes such as Nestin, MAP-2, and NeuN was detected. Immunostaining and high-performance thin-layer chromatography analysis showed that an increase in ganglioside biosynthesis was associated with neural differentiation of hDPSCs. Specifically, a significant increase in GD3 and GD1a expression was observed during neural differentiation. To confirm the role of gangliosides in neural differentiation, ganglioside biosynthesis was inhibited in hDPSCs by knockdown of UDP-glucose ceramide glucosyltransferase (Ugcg), which prevented differentiation into neural cells. These results suggest that gangliosides may play a role in the neural differentiation process of hDPSCs.     

Feeder-free Derivation of Neural Crest Progenitor Cells from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a source of transplantable cells for regenerative applications after disease or accidents. Neural crest (NC) cells are the precursors for a large variety of adult somatic cells, such as cells from the peripheral nervous system and glia, melanocytes and mesenchymal cells. They are a valuable source of cells to study aspects of human embryonic development, including cell fate specification and migration. Further differentiation of NC progenitor cells into terminally differentiated cell types offers the possibility to model human diseases in vitro, investigate disease mechanisms and generate cells for regenerative medicine. This article presents the adaptation of a currently available in vitro differentiation protocol for the derivation of NC cells from hPSCs. This new protocol requires 18 days of differentiation, is feeder-free, easily scalable and highly reproducible among human embryonic stem cell (hESC) lines as well as human induced pluripotent stem cell (hiPSC) lines. Both old and new protocols yield NC cells of equal identity.     

Multiple roles for Hox genes in segment-specific shaping of CNS lineages

In this “Extra View” article we highlight some of the recently accumulating evidence showing that Hox genes are involved at different steps during the development of neural cell lineages to control segmental patterning of the CNS. In addition to their well-known early role in establishing segmental identities, Hox genes act on neural stem cells and their progeny at various stages during embryonic and postembryonic development to control proliferation, cell fate and/or apoptosis in a segment-specific manner. This leads to differential shaping of serially homologous lineages and thus to structural diversification of segmental CNS units (neuromeres) in adaptation to their specific functional tasks in processing sensory information and generation of motor patterns.     

Amnion Epithelial Cells of Buffalo (Bubalus bubalis) Term Placenta Expressed Embryonic Stem Cells Markers and Differentiated into Cells of Neurogenic Lineage In Vitro

Aim of the present study was the isolation, culture, and characterization of amniotic membrane-derived epithelial cells (AE) from term placenta collected postpartum in buffalo. We found that cultured cells were of polygonal in shape, resistance to trypsin digestion and expressed cytokeratin-18 indicating that they were of epithelial origin. These cells have negative expression of mesenchymal stem cell markers (CD29, CD44, and CD105) and positive for pluripotency marker (OCT4) genes indicated that cultured cells were not contaminated with mesenchymal stem cells. Immunofluorescence staining with pluripotent stem cell surface markers, SSEA-1, SSEA-4, TRA-1-60, and TRA-1-81 indicated that these cells may retain pluripotent stem cell characteristics even after long period of differentiation. Differentiation potential of these cells was determined by their potential to differentiate into cells of neurogenic lineages using retinoic acid. In conclusion, we demonstrate that AE cells expressed pluripotent stem cell markers and have propensity to differentiate into cells of neurogenic lineage upon directed differentiation in vitro.     

Microporation is a valuable transfection method for efficient gene delivery into human umbilical cord blood-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) are an attractive source of adult stem cells for therapeutic application in clinical study. Genetic modification of MSCs with beneficial genes makes them more effective for therapeutic use. However, it is difficult to transduce genes into MSCs by common transfection methods, especially nonviral methods. In this study, we applied microporation technology as a novel electroporation technique to introduce enhanced green fluorescent protein (EGFP) and brain-derived neurotropfic factor (BDNF) plasmid DNA into human umbilical cord blood-derived MSCs (hUCB-MSCs) with significant efficiency, and investigated the stem cell potentiality of engineered MSCs through their phenotypes, proliferative capacity, ability to differentiate into multiple lineages, and migration ability towards malignant glioma cells.

Results

Using microporation with EGFP as a reporter gene, hUCB-MSCs were transfected with higher efficiency (83%) and only minimal cell damage than when conventional liposome-based reagent (<20%) or established electroporation methods were used (30-40%). More importantly, microporation did not affect the immunophenotype of hUCB-MSCs, their proliferation activity, ability to differentiate into mesodermal and ectodermal lineages, or migration ability towards cancer cells. In addition, the BDNF gene could be successfully transfected into hUCB-MSCs, and BDNF expression remained fairly constant for the first 2 weeks in vitro and in vivo. Moreover, microporation of BDNF gene into hUCB-MSCs promoted their in vitro differentiation into neural cells.

Conclusion

Taken together, the present data demonstrates the value of microporation as an efficient means of transfection of MSCs without changing their multiple properties. Gene delivery by microporation may enhance the feasibility of transgenic stem cell therapy.     

Identification of novel genes and networks governing hematopoietic stem cell development

Hematopoietic stem cells (HSCs) are capable of giving rise to all blood cell lineages throughout adulthood, and the generation of engraftable HSCs from human pluripotent stem cells is a major goal for regenerative medicine. Here, we describe a functional genome‐wide RNAi screen to identify genes required for the differentiation of embryonic stem cell (ESC) into hematopoietic stem/progenitor cells (HSPCs) in vitro. We report the discovery of novel genes important for the endothelial‐to‐hematopoietic transition and subsequently for HSPC specification. High‐throughput sequencing and bioinformatic analyses identified twelve groups of genes, including a set of 351 novel genes required for HSPC specification. As in vivo proof of concept, four of these genes, Ap2a1, Mettl22, Lrsam1, and Hal, are selected for validation, confirmed to be essential for HSPC development in zebrafish and for maintenance of human HSCs. Taken together, our results not only identify a number of novel regulatory genes and pathways essential for HSPC development but also serve as valuable resource for directed differentiation of therapy grade HSPCs using human pluripotent stem cells.     

In vitro extracorporeal shock wave treatment enhances stemness and preserves multipotency of rat and human adipose-derived stem cells

Background aimsAdipose-derived progenitor/stem cells (ASCs) are discussed as a promising candidate for various tissue engineering approaches. However, its applicability for the clinic is still difficult due to intra- and inter-donor heterogeneity and limited life span in vitro, influencing differentiation capacity as a consequence to decreased multipotency.MethodsExtracorporeal shock wave treatment has been proven to be a suitable clinical tool to improve regeneration of a variety of tissues for several decades, whereas the mechanisms underlying these beneficial effects remain widely unknown.ResultsIn this study we show that human and rat adipose derived stem cells respond strongly to repetitive shock wave treatment in vitro, resulting not only in maintenance and significant elevation of mesenchymal markers (CD73, CD90, CD105), but also in significantly increased differentiation capacity towards the osteogenic and adipogenic lineage as well as toward Schwann-cell like cells even after extended time in vitro, preserving multipotency of ASCs.ConclusionsESWT might be a promising tool to improve ASC quality for cell therapy in various tissue engineering and regenerative medicine applications.