Development of new non-viral systems for genetic modification of senescent cells

Senescence is a process characterized by a prolonged irreversible cell-cycle arrest. The accumulation of senescent cells in tissues is related to aging and to the development of age-related diseases. Recently, gene therapy has emerged as a powerful tool for treating age-associated diseases by the transference of specific genes into the target cell population. However, the high sensitivity of senescent cells significantly precludes their genetic modification via classical viral and non-viral systems. Niosomes are self-assembled non-viral nanocarriers that exhibit important advantages due to their elevated cytocompatibility, versatility, and cost-efficiency, arising as a new alternative for genetic modification of senescent cells. In this work, we explore for the first time the use of niosomes for genetic modification of senescent umbilical cord-derived mesenchymal stem cells. We report that niosome composition greatly affected transfection efficiency; those formulations prepared in medium with sucrose and containing cholesterol as helper lipid being the most suitable to transfect senescent cells. Moreover, resulting niosome formulations exhibited a superior transfection efficiency with a markedly less cytotoxicity than the commercial reagent Lipofectamine. These findings highlight the potentiality of niosomes as effective vectors for genetic modification of senescent cells, providing new tools for the prevention and/or treatment of age-related diseases.

Mesenchymal stromal cells for articular cartilage repair: preclinical studies

Rheumatic diseases such as osteoarthritis (OA) are a major social and economic burden because of the population aging and the lack of curative solutions. An effective cell therapy may be the best treatment option for OA and other cartilage diseases. However, the main cellular strategy used to repair articular cartilage, the transplantation of autologous chondrocytes, is limited to a small number of patients with traumatic lesions. The use of joint replacement after years of disease progression proves the great medical need in current practice. Mesenchymal stromal/stem cells (MSCs) provide an alternative cell source for cartilage regeneration due to numerous advantages, comprising relative ease to isolate and culture, chondrogenic capacity, and anti-inflammatory effects. Initial clinical trials with MSCs have led to encouraging results, but many variables have to be considered to attain true amelioration of disease or repair (type and status of cartilage disease, source and conditions of cells, administration regime, combinatorial approaches). Particularly, allogeneic MSCs are an advantageous cellular product. The animal models chosen for preclinical evaluation are also relevant for successful translation into clinical practice. Considering the limitations in the field, rigorous comparative and validating studies in well-established animal models (including large animals) are still needed to set up the bases for additional clinical trials. The present review of studies performed in small and large animal models should help clarify the applicability of MSC-based therapies for articular cartilage repair.

Corrigendum: Effect of age on pro-inflammatory miRNAs contained in mesenchymal stem cell-derived extracellular vesicles

This corrects the article DOI: 10.1038/srep43923.

Proteome analysis during chondrocyte differentiation in a new chondrogenesis model using human umbilical cord stroma mesenchymal stem cells

Umbilical cord stroma mesenchymal stem cells were differentiated toward chondrocyte-like cells using a new in vitro model that consists of the random formation of spheroids in a medium supplemented with fetal bovine serum on a nonadherent surface. The medium was changed after 2 days to one specific for the induction of chondrocyte differentiation. We assessed this model using reverse transcriptase-polymerase chain reaction, flow cytometry, immunohistochemistry, and secretome analyses. The purpose of this study was to determine which proteins were differentially expressed during chondrogenesis. Differential gel electrophoresis analysis was performed, followed by matrix-assisted laser desorption/ionization mass spectrometry protein identification. A total of 97 spots were modulated during the chondrogenesis process, 54 of these spots were identified as 39 different proteins and 15 were isoforms. Of the 39 different proteins identified 15 were down-regulated, 21 were up-regulated, and 3 were up- and down-regulated during the chondrogenesis process. Using Pathway Studio 7.0 software, our results showed that the major cell functions modulated during chondrogenesis were cellular differentiation, proliferation, and migration. Five proteins involved in cartilage extracellular matrix metabolism found during the differential gel electrophoresis study were confirmed using Western blot. The results indicate that our in vitro chondrogenesis model is an efficient and rapid technique for obtaining cells similar to chondrocytes that express proteins characteristic of the cartilage extracellular matrix. These chondrocyte-like cells could prove useful for future cell therapy treatment of cartilage pathologies.

Analysis of the chondrogenic potential and secretome of mesenchymal stem cells derived from human umbilical cord stroma

Mesenchymal stem cells (MSCs) from umbilical cord stroma were isolated by plastic adherence and characterized by flow cytometry, looking for cells positive for OCT3/4 and SSEA-4 as well as the classic MSC markers CD44, CD73, CD90, Ki67, CD105, and CD106 and negative for CD34 and CD45. Quantitative reverse transcriptase-polymerase chain reaction analysis of the genes ALP, MEF2C, MyoD, LPL, FAB4, and AMP, characteristic for the differentiated lineages, were used to evaluate early and late differentiation of 3 germ lines. Direct chondrogenic differentiation was achieved through spheroid formation by MSCs in a chondrogenic medium and the presence of chondrogenic markers at 4, 7, 14, 28, and 46 days of culture was tested. Immunohistochemistry and quantitative reverse transcriptase-polymerase chain reaction analyses were utilized to assess the expression of collagen type I, collagen type II, and collagen type X throughout the time studied. We found expression of all the markers as early as 4 days of chondrogenic differentiation culture, with their expression increasing with time, except for collagen type I, which decreased in expression in the formed spheroids after 4 days of differentiation. The signaling role of Wnt during chondrogenic differentiation was studied by western blot. We observed that β-catenin expression decreased during the chondrogenic process. Further, a secretome study to validate our model of differentiation in vitro was performed on spheroids formed during the chondrogenesis process. Our results indicate the multipotential capacity of this source of human cells; their chondrogenic capacity could be useful for future cell therapy in articular diseases.

Chondrogenic potential of subpopulations of cells expressing mesenchymal stem cell markers derived from human synovial membranes

In this study we analyzed the chondrogenic potential of subpopulations of mesenchymal stem cells (MSCs) derived from human synovial membranes enriched for CD73, CD106, and CD271 markers. Subpopulations of human synovial membrane MSCs enriched for CD73, CD106, and CD271 markers were isolated using a cytometry sorter and characterized by flow cytometry for MSC markers. The expression of Sox9, Nanog, and Runx2 genes by these cells was measured by reverse transcriptase-polymerase chain reaction. The chondrogenesis of each subpopulation was assessed by culturing the cells in a defined medium to produce spontaneous spheroid formation and differentiation towards chondrocyte-like cells. The examination of the spheroids by histological and immunohistochemical analyses for collagen type II (COL2), aggrecan, collagen type I (COL1), metalloprotease 13 (MMP13), and collagen type X (COLX) levels were performed to assess their chondrogenesis capacity. The adipogenesis and osteogenesis potential of each subpopulation was determined using commercial media; the resulting cells were stained with oil red O or red alizarin to test the degree of differentiation. The subpopulations had different profiles of cells positive for the MSC markers CD44, CD69, CD73, CD90, and CD105 and showed different expression levels of the genes Sox9, Nanog, and Runx2 involved in chondrogenesis, undifferentiation, and osteoblastogenesis, respectively. Immunohistochemical analysis demonstrated that COL1, COL2, COLX, MMP13, and aggrecan were expressed in the spheroids as soon as 14 days of culture. The CD271(+) subpopulation expressed the highest levels of COL2 staining compared to the other subpopulations. CD105 and Runx2 were shown by immunohistochemistry and genetic analysis to have significantly higher expression CD271(+) subpopulation than the other subpopulations. Spheroids formed from CD271-enriched and CD73-enriched MSCs from normal human synovial membranes mimic the native cartilage extracellular matrix more closely than CD106(+) MSCs and are possible candidates for use in cartilage tissue engineering. Both cell types have potential for promoting the differentiation of MSCs into chondrocytes, presenting new possibilities for achieving intrinsic cartilage repair.

Differentiation of synovial CD-105(+) human mesenchymal stem cells into chondrocyte-like cells through spheroid formation

Mesenchymal stem cells (MSCs) have the capacity to differentiate into several cell lineages, some of which can generate bone, cartilage, or adipose tissue. The presence of MSCs in the synovial membrane was recently reported. Data from comparative studies of MSCs derived from various mesenchymal tissues suggest that MSCs from synovial membranes have a superior chondrogenesis capacity. Previous chondrogenic differentiation studies have used the total population of MSCs, including cells with several MSC markers, such as CD44, CD90, CD105, or CD73. However the chondrogenic capacity of an individual population of MSCs has not been examined. Our aim was to study the chondrogenic capacity of the cellular MSC subset, CD105(+), derived from synovial membrane tissues of patients with osteoarthritis (OA) and normal donors. The tissues were digested with a cocktail of collagenase/dispase and the isolated MSCs were seeded into plates. The subpopulation of CD105(+)-MSCs was separated using a magnetic separator. The MSCs were then differentiated towards chondrocyte-like cells using a specific medium to promote spheroid formation. Spheroids were collected after 14, 28, and 46 days in chondrogenic medium and stained with hematoxylin, eosin, Safranin O or Alcian blue to evaluate the extracellular matrix. Immunohistochemistry was performed to study collagen types I (COLI) and II (COLII) and aggrecan expression. Phenotypic characterization of the isolated CD105(+)-MSCs shows that these cells are also positive for CD90 and CD44, but negatives for CD34 and CD45. In addition, this cellular subset expressed Sox-9. Spheroids appeared after 7 days in culture in the presence of chondrogenic medium. Our studies show no differences between MSCs obtained from OA and normal synovial membranes during chondrogenesis. The morphological analysis of spheroids revealed characteristics typical of chondrocyte cells. The intensity of Safranin O, Alcian blue and aggrecan staining was positive and constant throughout the culture period. However, the intensity of COL2 staining was higher at 28 days (84.29 +/- 0.1 U) than at 46 days (61.28 +/- 01 U), while COL1 staining was not detected in any samples analyzed. These results were confirmed by reverse transcriptase-polymerase chain reaction assays. We conclude that the cellular subset of CD105(+)-MSCs has chondrogenic capacity. The study also show the similar chondrogenic capacity of CD105(+)-MSCs cultured from normal and OA synovial membranes.

Differentiation of murine embryonic stem cells to thyrocytes requires insulin and insulin-like growth factor-1

The mechanisms controlling thyrocyte development during embryonic stem (ES) cell differentiation have only been partially elucidated, although previous studies have suggested the participation of thyroid stimulating hormone (TSH) in these processes. To further define the role of TSH in this context, we have studied a murine ES cell line in which green fluorescent protein (GFP) cDNA is targeted to the TSH receptor (TSHR) gene, linking the expression of GFP to the transcription of the endogenous TSHR gene. We demonstrate that, in the initial stages of embryoid body formation, activin A and TSH induce the differentiation of definitive endoderm and thyrocyte progenitors expressing Sox17, Foxa2, and TSHR. These thyrocyte progenitors are then converted into cellular aggregates that, in the presence of insulin and IGF-1, further differentiate into mature thyroglobulin-expressing thyrocytes. Our data suggest that, despite the fact that TSH is important for the induction and specification of thyrocytes from ES cells, insulin and IGF-1 are crucial for thyrocyte maturation. Our method provides a powerful in vitro differentiation model for studying the mechanisms of early thyrocyte lineage development.

Directed differentiation of mouse embryonic stem cells into thyroid follicular cells

Elucidating the molecular mechanisms leading to the induction and specification of thyroid follicular cells is important for our understanding of thyroid development. To characterize the key events in this process, we previously established an experimental embryonic stem (ES) cell model system, which shows that wild-type mouse CCE ES cells can give rise to thyrocyte-like cells in vitro. We extend our analysis in this report by using a genetically manipulated ES cell line in which green fluorescent protein (GFP) cDNA is targeted to the TSH receptor (TSHR) gene, linking GFP expression to the transcription of the endogenous TSHR gene. The appearance of GFP-positive cells was dependent on the formation of embryoid bodies from undifferentiated ES cells and was greatly enhanced by TSH treatment during the first 2-4 d of differentiation. With the support of Matrigel, highly enriched ES cell-derived GFP-positive cells formed thyroid follicle-like clusters in a serum-free medium supplemented with TSH. Importantly, these clusters display the characteristics of thyroid follicular cells. Immunofluorescent studies confirmed the colocalization of TSHR with the Na+/I- symporter in the clusters and indicated that Na+/I- symporter was expressed exclusively in the plasma membrane. In addition, I- uptake activity was observed in these cells. Our results indicate that ES cells can be induced to differentiate into thyroid follicular cells, providing a powerful tool to study embryonic thyroid development and function.

Endogenous excitatory amino acid neurotransmission regulates thyroid-stimulating hormone and thyroid hormone secretion in conscious freely moving male rats

The role of neurotransmission of endogenous excitatory amino acid (EAA) on serum thyroid hormones and thyroid-stimulating hormone (TSH) levels was examined in conscious and freely moving adult male Sprague-Dawley rats. The rats were cannulated at the third ventricle 2 d before the experiments. Several glutamate receptor agonists, such as kainic acid and domoic acid, and antagonists, such as 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and dizocilpine (MK-801) were administered into the third ventricle. Serum TSH levels were assesed by radioimmunoassay, and serum thyroid hormone levels were assessed by enzyme immunoassay. The results showed that the administration of CNQX and MK-801 produced a decrease in serum levels of TSH and thyroid hormones. The administration of kainic acid and domoic acid increased TSH concentrations, whereas CNQX completely blocked the release of TSH induced by kainic acid and domoic acid. These results suggest the importance of endogenous EAA in the regulation of hormone secretion from the pituitary-thyroid axis, as well as the role of the N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the stimulatory effect of EAAs on the pituitary-thyroid axis.

Effect of excitatory amino acids on serum TSH and thyroid hormone levels in freely moving rats

The actions of glutamate (L-Glu), and glutamate receptor agonists on serum thyroid hormones (T4 and T3) and TSH levels have been studied in conscious and freely moving adult male rats. The excitatory amino acids (EAA), L-Glu, N-methyl-D-aspartate (NMDA), kainic acid (KA) and domoic acid (Dom) were administered intraperitoneally. Blood samples were collected through a cannula implanted in the rats jugular 0--60 min after injection. Thyroid hormone concentrations were measured by enzyme immunoassay, and thyrotrophin (TSH) concentrations were determined by radioimmunoassay. The results showed that L-Glu (20 and 25 mg/kg) and NMDA (25 mg/kg) increased serum thyroxine (T4), triiodothyronine (T3) and TSH concentrations. Serum thyroid hormone levels increased 30 min after treatment, while serum TSH levels increased 5 min after i.p. administration, in both cases serum levels remained elevated during one hour. Injection of the non-NMDA glutamatergic agonists KA (30 mg/kg) and Dom (1 mg/kg) produced an increase in serum thyroid hormones and TSH levels. These results suggest the importance of EAAs in the regulation of hormone secretion from the pituitary-thyroid axis, as well as the importance of the NMDA and non-NMDA receptors in this stimulatory effect.

Effect of okadaic acid and calyculin-A, two protein phosphatase inhibitors, on thyrotropin-stimulated triiodothyronine secretion in cultured sheep thyroid cells

We have studied the effect of two protein phosphatase inhibitors on thyrotropin (TSH)-stimulated triiodothyronine (T3) production by sheep thyroid cells grown in primary culture. Incubation of sheep thyrocytes with okadaic acid (OA) and calyculin-A (CL-A), two potent inhibitors of type 1 (PP1) and type 2A (PP2A) protein phosphatases, resulted in an increase of TSH-stimulated T3 production. This effect was detected using concentrations as low as 0.1 pM with OA and 1 fM with CL-A. An inhibitory effect on T3 production, due to cellular death, was observed with 6 nM OA and 1 nM CL-A. In the absence of TSH, OA or CL-A had no effect on T3 production by thyrocytes. Forskoline (10 microM), an activator of adenylate cyclase, increased the basal and TSH-stimulated T3 release by sheep thyroid cells; this effect was increased by OA in cells grown in the basal state but not in the presence of TSH. These results suggest that the marine toxins OA and CL-A, two potent inhibitors of PP-1 and PP-2A, have significant stimulatory effects on T3 secretion promoted by TSH and FK. These observations indicate that these proteins could be important mediators of thyroid hormone production.

Validation of an EIA kit for determination of total thyroid hormones in rat serum. Effects of different anaesthetics

Two enzyme immunoassays for the quantitative determination of total thyroxine (T4) and total triiodothyronine (T3) in human serum were validated to measure total T4 and T3 in rat serum. The specificity, sensitivity, detectability and reproducibility have been tested as well as the effects of different anaesthetics (pentobarbital and a mixture of ketamine and xylacine) on serum thyroid hormone levels. Hormones were quantified, by means of a previously validated technique, 18 hours after surgery for the placement of a stem for blood extraction in conscious and freely moving animals. Thyroid serum levels, especially T3, were slightly lower in xylacine plus ketamine treated animals than in those treated with pentobarbital. The administration of glutamic acid, stimulated the secretion of thyroid hormones, this effect appearing 30 minutes after its administration and it was independent of the anaesthetic used during the surgery for the cannula placement, although in pentobarbital treated rats, the serum T3 level increase induced by glutamate appears 60 minutes after the treatment.

Effects of domoic acid on serum levels of TSH and thyroid hormones

The actions of Domoic Acid (Dom), a marine toxin, on the levels of serum TSH and thyroid hormones (T4 and T3) has been studied to determine if these actions could be mediated by the serotoninergic system. In all the experiments, adult male Wistar rats were used. The Dom dissolved in saline was administered via i.p. in doses of 0.5 and 1 mg/kg. The T4 and T3 concentrations were determined by enzimoinmunoassay and TSH concentration was determined by radioinmunoassay. The results show that Dom 1 mg/kg increases the serum T4 levels one hour after treatment and decreases these levels 2 and 3 hr after treatment. Dom 0.5 mg/kg decreased the serum T4 levels 2 and 3 hr after treatment. The concentrations of T3 in serum were unchanged by both doses of Dom. The concentration of TSH was increased by Dom. In order to study the possible mediation of the serotoninergic system in the effect of Dom on the hormone levels, PCPA, a tryptophan hydroxylase inhibitor, was administered i.p. 90 min before blood sampling. In this case, with both doses of Dom a decrease in the levels of both hormones occurred with respect to the PCPA group. These results indicate that the serotoninergic system could affect the actions of Dom on TSH and thyroid hormone secretion.

Effect of domoic acid on brain amino acid levels

The administration of Domoic Acid (Dom) in a 0.2 mg/kg i.p. dose induces changes in the levels of amino acids of neurochemical interest (Asp, Glu, Gly, Tau, Ala, GABA) in different rat brain regions (hypothalamus, hippocampus, amygdala, striatum, cortex and midbrain). The most affected amino acid is the GABA, the main inhibitory amino acid neurotransmitter, whereas glutamate, the main excitatory amino acid, is not affected. The rat brain regions that seem to be the main target of the Dom action belong to the limbic system (hippocampus, amygdala). The possible implication of the amino acids in the actions of Dom is also discussed.