The Combination of Single-Cell and Next-Generation Sequencing Can Reveal Mosaicism for BRCA2 Mutations and the Fine Molecular Details of Tumorigenesis.

Germline mutations in the BRCA1 and BRCA2 genes are responsible for hereditary breast and ovarian cancer syndrome. Germline and somatic BRCA1/2 mutations may define therapeutic targets and refine cancer treatment options. However, routine BRCA diagnostic approaches cannot reveal the exact time and origin of BRCA1/2 mutation formation, and thus, the fine details of their contribution to tumor progression remain less clear. Here, we establish a diagnostic pipeline using high-resolution microscopy and laser microcapture microscopy to test for BRCA1/2 mutations in the tumor at the single-cell level, followed by deep next-generation sequencing of various tissues from the patient. To demonstrate the power of our approach, here, we describe a detailed single-cell-level analysis of an ovarian cancer patient we found to exhibit constitutional somatic mosaicism of a pathogenic BRCA2 mutation. Employing next-generation sequencing, BRCA2 c.7795G>T, p.(Glu2599Ter) was detected in 78% of reads in DNA extracted from ovarian cancer tissue and 25% of reads in DNA derived from peripheral blood, which differs significantly from the expected 50% of a hereditary mutation. The BRCA2 mutation was subsequently observed at 17-20% levels in the normal ovarian and buccal tissue of the patient. Together, our findings suggest that this mutation occurred early in embryonic development. Characterization of the mosaic mutation at the single-cell level contributes to a better understanding of BRCA mutation formation and supports the concept that the combination of single-cell and next-generation sequencing methods is advantageous over traditional mutational analysis methods. This study is the first to characterize constitutional mosaicism down to the single-cell level, and it demonstrates that BRCA2 mosaicism occurring early during embryogenesis can drive tumorigenesis in ovarian cancer.

A Regenerative Approach to Canine Osteoarthritis Using Allogeneic, Adipose-Derived Mesenchymal Stem Cells. Safety Results of a Long-Term Follow-Up.

Mesenchymal stem cells (MSC) are emerging as an effective therapeutic tool in treating canine osteoarthritis (OA). In this report, we focused on the questions of whether MSC transplantation has long-term beneficial effects for the improvement in motion and also evaluated the safety of MSC injection. Visceral adipose tissue, a surgical waste obtained during routine ovariectomy served as a source of allogeneic MSCs and used to treat OA. Altogether, fifty-eight dogs were transplanted in the study suffering from OA in the elbow (42 animals), hip (5), knee (8), ankle (2), and hock (1). The effect of MSC transplantation was evaluated by the degree of lameness at a 4-5-years follow-up period based on the owners' subjective observations. The results showed that 83% of the OA patients improved or retained improvement in lameness. Clinical safety of the treatment was assessed by evaluating the coincidence of tumors or other diseases and other adverse reactions (such as local inflammation) after MSC cell therapy. Two incidences of local inflammation for <1 week at the site of injection were reported. No other adverse reactions were detected post-treatment. Sixteen dogs died during the study, 4 due to cancer and 12 due to other diseases, diagnosed by veterinarians. Overall, our survey suggests that MSC transplantation has long-term beneficial effects in reducing lameness. Moreover, no enrichment in a specific cause of death was observed in the transplanted animals, compared to reported literature. Our data suggest that MSC treatment could be an effective and safe long-term therapy for canine OA.

Characterization and therapeutic application of canine adipose mesenchymal stem cells to treat elbow osteoarthritis.

Visceral adipose tissue (AT) obtained from surgical waste during routine ovariectomies was used as a source for isolating canine mesenchymal stem cells (MSCs). As determined by cytofluorimetry, passage 2 cells expressed MSC markers CD44 and CD90 and were negative for lineage-specific markers CD34 and CD45. The cells differentiated toward osteogenic, adipogenic, and chondrogenic directions. With therapeutic aims, 30 dogs (39 joints) suffering from elbow dysplasia (ED) and osteoarthritis (OA) were intra-articularly transplanted with allogeneic MSCs suspended in 0.5% hyaluronic acid (HA). A highly significant improvement was achieved without any medication as demonstrated by the degree of lameness during the follow-up period of 1 y. Control arthroscopy of 1 transplanted dog indicated that the cartilage had regenerated. Histological analysis of the cartilage biopsy confirmed that the regenerated cartilage was of hyaline type. These results demonstrate that transplantation of allogeneic adipose tissue-derived mesenchymal stem cells (AT-MSCs) is a novel, noninvasive, and highly effective therapeutic tool in treating canine elbow dysplasia.

Du tissu adipeux viscéral (TA) obtenu de résidus chirurgicaux lors d'ovariectomies de routine a été utilisé comme source pour isoler des cellules souches mésenchymateuses canines (CSMs). Tel que déterminé par cytofluorométrie, les cellules du 2e passage exprimaient les marqueurs de CSM CD44 et CD90, et étaient négatives pour les marqueurs spécifiques de lignée CD34 et CD45. Les cellules se sont différenciées dans des directions ostéogéniques, adipogéniques, et chondrogéniques. À des fins thérapeutiques, 30 chiens (39 articulations) souffrant de dysplasie du coude (DC) et d'ostéoarthrite (OA) ont reçu une transplantation intra articulaire de CSMs allogéniques en suspension dans 0,5 % d'acide hyaluronique (AH). Une amélioration hautement significative a été obtenue sans aucune médication tel que démontré par le degré de boiterie durant la période de suivi de 1 an. Une arthroscopie de contrôle de un des chiens ayant reçu une transplantation montrait que le cartilage s'était régénéré. L'analyse histologique de la biopsie du cartilage a confirmé que le cartilage régénéré était de type hyalin. Ces résultats démontrent que la transplantation de cellules souches mésenchymateuses dérivées de tissu adipeux allogène est un outil thérapeutique novateur, non-invasif, et très efficace pour traiter la dysplasie du coude chez le chien.(Traduit par Docteur Serge Messier).

Galectin-1 is a local but not systemic immunomodulatory factor in mesenchymal stromal cells.

BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) have powerful immunosuppressive activity. This function of MSCs is attributed to plethora of the expressed immunosuppressive factors, such as galectin-1 (Gal-1), a pleiotropic lectin with robust anti-inflammatory effect. Nevertheless, whether Gal-1 renders or contributes to the immunosuppressive effect of MSCs has not been clearly established. Therefore, this question was the focus of a complex study. METHODS: MSCs were isolated from bone marrows of wild-type and Gal-1 knockout mice and their in vitro anti-proliferative and apoptosis-inducing effects on activated T cells were examined. The in vivo immunosuppressive activity was tested in murine models of type I diabetes and delayed-type hypersensitivity. RESULTS: Both Gal-1-expressing and -deficient MSCs inhibited T-cell proliferation. Inhibition of T-cell proliferation by MSCs was mediated by nitric oxide but not PD-L1 or Gal-1. In contrast, MSC-derived Gal-1 triggered apoptosis in activated T cells that were directly coupled to MSCs, representing a low proportion of the T-cell population. Furthermore, absence of Gal-1 in MSCs did not affect their in vivo immunosuppressive effect. CONCLUSIONS: These results serve as evidence that Gal-1 does not play a role in the systemic immunosuppressive effect of MSCs. However, a local contribution of Gal-1 to modulation of T-cell response by direct cell-to-cell interaction cannot be excluded. Notably, this study serves a good model to understand how the specificity of a pleiotropic protein depends on the type and localization of the producing effector cell and its target.

Licensing by Inflammatory Cytokines Abolishes Heterogeneity of Immunosuppressive Function of Mesenchymal Stem Cell Population.

When mesenchymal stem cells (MSCs) are used for therapy of immunological pathologies, they get into an inflammatory environment, altering the effectiveness of the treatment. To establish the impact of environmental inflammatory factors on MSCs' immunofunction in the mirror of intrinsic heterogeneity of mouse MSC population, individual MSC clones were generated and characterized. Adipogenic but not osteogenic differentiation and pro-angiogenic activity of five independent MSC cell lines were similar. Regarding osteogenic differentiation, clones MSC3 and MSC6 exhibited poorer capacity than MSC2, MSC4, and MSC5. To study the immunosuppressive heterogeneity, in vitro and in vivo experiments have been carried out using T-cell proliferation assay and delayed-type hypersensitivity (DTH) response, respectively. A remarkable difference was found between the clones in their ability to inhibit T-cell proliferation in the following order: MSC2≥MSC5>MSC4>MSC3 >> MSC6. Nevertheless, the differences between the immunosuppressive activities of the individual clones disappeared on pretreatment of the cells with pro-inflammatory cytokines, a procedure called licensing. Stimulation of all clones with IFN-γ and TNF-α resulted in elevation of their inhibitory capability to a similar level. Nitric oxide (NO) and prostaglandin E2 (PGE2) were identified as major mediators of immunofunction of the MSC clones. The earlier findings were also supported by in vivo results. Without licensing, MSC2 inhibited DTH response, while MSC6 did not affect DTH response. In contrast, prestimulation of MSC6 with inflammatory cytokines resulted in strong suppression by this clone as well. Here, we have showed that MSC population is functionally heterogeneous in terms of immunosuppressive function; however, this variability is largely reduced under pro-inflammatory conditions.

Novel role for galectin-1 in T-cells under physiological and pathological conditions.

Secreted, extracellular galectin-1 (exGal-1) but not intracellular Gal-1 (inGal-1) has been described as a strong immunosuppressive protein due to its major activity of inducing apoptosis of activated T-cells. It has previously been reported that T-cells express Gal-1 upon activation, however its participation in T-cell functions has remained largely elusive. To determine function of Gal-1 expressed by activated T-cells we have carried out a series of experiments. We have shown that Gal-1, expressed in Gal-1-transgenic Jurkat cells or in activated T-cells, remained intracellularly indicating that Gal-1-induced T-cell death was not a result of an autocrine effect of the de novo expressed Gal-1. Rather, a particular consequence of the inGal-1 expression was that T-cells became more sensitive to exGal-1 added either as a soluble protein or bound to the surface of a Gal-1-secreting effector cell. This was also verified when the susceptibility of activated T-cells from wild type or Gal-1 knockout mice to Gal-1-induced apoptosis were compared. Murine T-cells expressing Gal-1 were more sensitive to the cytotoxicity of the exGal-1 than their Gal-1 knockout counterparts. We also conducted a study with activated T-cells from patients with systemic lupus erythematosus (SLE), a disease in which dysregulated T-cell apoptosis has been well described. SLE T-cells expressed lower amounts of Gal-1 than healthy T-cells and were less sensitive to exGal-1. These results suggested a novel role of inGal-1 in T-cells as a regulator of T-cell response to exGal-1, and its likely contribution to the mechanism in T-cell apoptosis deficiency in lupus.

GM1 controlled lateral segregation of tyrosine kinase Lck predispose T-cells to cell-derived galectin-1-induced apoptosis.

One prominent immunoregulatory function of galectin-1 (Gal-1), a ß-galactoside binding mammalian lectin, is induction of apoptosis in activated T-cells by a process depending on the activity of Src family tyrosine kinase, Lck. Although the requirement for Lck in Gal-1 induced T-cell death and the ability of Gal-1 to affect the membrane localization of extracellular Gal-1-binding proteins have been well documented, the consequence of the complex and related reorganization of extra- and intracellular signaling components upon Gal-1 treatment of T-cells has not yet been revealed. Therefore, we have analyzed the plasma membrane movement of Lck upon Gal-1 triggered signaling, and the significance of this event in Gal-1 induced T-cell death. Non-receptor tyrosine kinase, Lck primarily localized in the synapse of tumor cell-T-cell during 15 min of the established direct cell contact. Later, after 30 min, a lateral segregation of Lck from the cell synapse was observed. The migration of Lck to the opposite of the cell contact apparently depended on the expression and cell surface presentation of Gal-1 on the effector (tumor) cells and was accompanied by phosphorylation on the negative regulatory tyrosine residue, Tyr505. Receptor tyrosine phosphatase, CD45 played crucial role in this event since CD45 deficiency or inhibition of its phosphatase activity resulted in the failure of Lck membrane movement. Level of the Gal-1-binding glycolipid GM1 ganglioside also essentially regulated Lck localization. Segregation of Lck and Gal-1 induced apoptosis was diminished in T-cells with low GM1 expression compared to T-cells with high GM1. Our results show that spatial regulation of Lck by CD45 and GM1 ganglioside determines the outcome of apoptotic response to Gal-1 and this local regulation may occur only upon intimate effector (Gal-1 expressing) cell-T-cell attachment.

Foldameric α/ß-peptide analogs of the ß-sheet-forming antiangiogenic anginex: structure and bioactivity.

The principles of ß-sheet folding and design for α-peptidic sequences are well established, while those for sheet mimetics containing homologated amino acid building blocks are still under investigation. To reveal the structure-function relations of ß-amino-acid-containing foldamers, we followed a top-down approach to study a series of α/ß-peptidic analogs of anginex, a ß-sheet-forming antiangiogenic peptide. Eight anginex analogs were developed by systematic α → ß(3) substitutions and analyzed by using NMR and CD spectroscopy. The foldamers retained the ß-sheet tendency, though with a decreased folding propensity. ß-Sheet formation could be induced by a micellar environment, similarly to that of the parent peptide. The destructuring effect was higher when the α → ß(3) exchange was located in the ß-sheet core. Analysis of the ß-sheet stability versus substitution pattern and the local conformational bias of the bulky ß(3)V and ß(3)I residues revealed that a mismatch between the H-bonding preferences of the α- and ß-residues played a minor role in the structure-breaking effect. Temperature-dependent CD and NMR measurements showed that the hydrophobic stabilization was scaled-down for the α/ß-peptides. Analysis of the biological activity of the foldamer peptides showed that four anginex derivatives dose-dependently inhibited the proliferation of a mouse endothelial cell line. The α → ß(3) substitution strategy applied in this work can be a useful approach to the construction of bioactive ß-sheet mimetics with a reduced aggregation tendency and improved pharmacokinetic properties.

Identification of galectin-1 as a critical factor in function of mouse mesenchymal stromal cell-mediated tumor promotion.

Bone marrow derived mesenchymal stromal cells (MSCs) have recently been implicated as one source of the tumor-associated stroma, which plays essential role in regulating tumor progression. In spite of the intensive research, the individual factors in MSCs controlling tumor progression have not been adequately defined. In the present study we have examined the role of galectin-1 (Gal-1), a protein highly expressed in tumors with poor prognosis, in MSCs in the course of tumor development. Co-transplantation of wild type MSCs with 4T1 mouse breast carcinoma cells enhances the incidence of palpable tumors, growth, vascularization and metastasis. It also reduces survival compared to animals treated with tumor cells alone or in combination with Gal-1 knockout MSCs. In vitro studies show that the absence of Gal-1 in MSCs does not affect the number of migrating MSCs toward the tumor cells, which is supported by the in vivo migration of intravenously injected MSCs into the tumor. Moreover, differentiation of endothelial cells into blood vessel-like structures strongly depends on the expression of Gal-1 in MSCs. Vital role of Gal-1 in MSCs has been further verified in Gal-1 knockout mice. By administering B16F10 melanoma cells into Gal-1 deficient animals, tumor growth is highly reduced compared to wild type animals. Nevertheless, co-injection of wild type but not Gal-1 deficient MSCs results in dramatic tumor growth and development.These results confirm that galectin-1 is one of the critical factors in MSCs regulating tumor progression.