Mesenchymal Stromal Cells Cultures Research Articles

Differential Smad2/3 linker phosphorylation is a crosstalk mechanism of Rho/ROCK and canonical TGF-β3 signaling in tenogenic differentiation

The transforming growth factor (TGF)-β3 is a well-known inducer for tenogenic differentiation, signaling via the Smad2/3 pathway. Furthermore, other factors like extracellular matrix or mechanical force can induce tenogenic differentiation and possibly alter the response to TGF-β3 by signaling via the Rho/ROCK pathway. The aim of this study was to investigate the interplay of Rho/ROCK and TGF-β3/Smad signaling in tenogenic differentiation, with the Smad2/3 molecule hypothesized as a possible interface. Cultured as monolayers or on collagen I matrices, mesenchymal stromal cells (MSC) were treated with the ROCK inhibitor Y-27632 (10 µM), TGF-β3 (10 ng/ml) or both combined. Control cells were cultured accordingly, without Y-27632 and/or without TGF-β3. At different time points, MSC were analyzed by real-time RT-PCR, immunofluorescence, and Western blot. Cultivation of MSC on collagen matrices and ROCK inhibition supported tenogenic differentiation and fostered the effect of TGF-β3. The phosphorylation of the linker region of Smad2 was reduced by cultivation on collagen matrices, but not by ROCK inhibition. The latter, however, led to increased phosphorylation of the linker region of Smad3. In conclusion, collagen matrices and the Rho/ROCK signaling pathway influence the TGF-β3/Smad2/3 pathway by regulating different phosphorylation sites of the Smad linker region.

Mesenchymal stromal cell chondrogenesis under ALK1/2/3-specific BMP inhibition: a revision of the prohypertrophic signalling network concept

BackgroundIn vitro chondrogenesis of mesenchymal stromal cells (MSCs) driven by the essential chondro-inducer transforming growth factor (TGF)-β is instable and yields undesired hypertrophic cartilage predisposed to bone formation in vivo. TGF-β can non-canonically activate bone morphogenetic protein-associated ALK1/2/3 receptors. These have been accused of driving hypertrophic MSC misdifferentiation, but data remained conflicting. We here tested the antihypertrophic capacity of two highly specific ALK1/2/3 inhibitors – compound A (CompA) and LDN-212854 (LDN21) – in order to reveal potential prohypertrophic contributions of these BMP/non-canonical TGF-β receptors during MSC in vitro chondrogenesis.MethodsStandard chondrogenic pellet cultures of human bone marrow-derived MSCs were treated with TGF-β and CompA (500 nM) or LDN21 (500 nM). Daily 6-hour pulses of parathyroid hormone-related peptide (PTHrP[1–34], 2.5 nM, from day 7) served as potent antihypertrophic control treatment. Day 28 samples were subcutaneously implanted into immunodeficient mice.ResultsAll groups underwent strong chondrogenesis, but GAG/DNA deposition and ACAN expression were slightly but significantly reduced by ALK inhibition compared to solvent controls along with a mild decrease of the hypertrophy markers IHH-, SPP1-mRNA, and Alkaline phosphatase (ALP) activity. When corrected for the degree of chondrogenesis (COL2A1 expression), only pulsed PTHrP but not ALK1/2/3 inhibition qualified as antihypertrophic treatment. In vivo, all subcutaneous cartilaginous implants mineralized within 8 weeks, but PTHrP pretreated samples formed less bone and attracted significantly less haematopoietic marrow than ALK1/2/3 inhibitor groups.ConclusionsOverall, our data show that BMP-ALK1/2/3 inhibition cannot program mesenchymal stromal cells toward stable chondrogenesis. BMP-ALK1/2/3 signalling is no driver of hypertrophic MSC misdifferentiation and BMP receptor induction is not an adverse prohypertrophic side effect of TGF-β that leads to endochondral MSC misdifferentiation. Instead, the prohypertrophic network comprises misregulated PTHrP/hedgehog signalling and WNT activity, and a potential contribution of TGF-β-ALK4/5-mediated SMAD1/5/9 signalling should be further investigated to decide about its postulated prohypertrophic activity. This will help to successfully engineer cartilage replacement tissues from MSCs in vitro and translate these into clinical cartilage regenerative therapies.

The Use of Human Platelet Lysate as a Coating Substance for Adipose-Derived Stem Cell Expansion.

Large-scale production of mesenchymal stromal cells is essential for sufficient therapeutic doses in regenerative medicine. However, long-term cultivation encounters limited cell growth and cellular aging. Therefore, an alternative cell culture approach that promotes proliferation and attenuates cell senescence is required. Human platelet lysate (HPL) is a potent supplement for in vitro cell expansion. Applying HPL as a coating material can potentially improve mesenchymal stromal cell cultures. To examine the capacity of HPL, it was used to pre-coat a tissue culture plate for in vitro adipose-derived mesenchymal stromal cell expansion. Alterations in biological features of adipose-derived stem cells (ADSCs) were investigated, including cell adhesion assays, cell proliferation, population doubling time, and cellular senescence. ADSCs cultured on HPL-coated plates significantly increased cell adhesion rate, shortened population doubling time, and stimulated cell growth. The senescent cells were significantly decreased in ADSCs cultured in an HPL-coated plate, and the expression levels of senescence-associated genes, including p16, p21, and p53, were downregulated. Furthermore, Western blotting analysis revealed that HPL was enriched with fibronectin and vitronectin, essential cell adhesive proteins. HPL was effectively used as a coating material for ADSC expansions. Cellular cultivation on the HPL coating is an alternative approach for producing mesenchymal stromal cells.

Transitioning from static to suspension culture system for large-scale production of xeno-free extracellular vesicles derived from mesenchymal stromal cells.

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have shown increasing therapeutic potential in the last years. However, large production of EV is required for therapeutic purposes. Thereby, scaling up MSC cultivation in bioreactors is essential to allow culture parameters monitoring. In this study, we reported the establishment of a scalable bioprocess to produce MSC-EV in suspension cultures using spinner flasks and human collagen-coated microcarriers (3D culture system). We compared the EV production in this 3D culture system with the standard static culture using T-flasks (2D culture system). The EV produced in both systems were characterized and quantify by western blotting and nanoparticle tracking analysis. The presence of the typical protein markers CD9, CD63, and CD81 was confirmed by western blotting analyses for EV produced in both culture systems. The cell fold-increase was 5.7-fold for the 3D culture system and 4.6-fold for the 2D culture system, signifying a fold-change of 1.2 (calculated as the ratio of fold-increase 3D to fold-increase 2D). Furthermore, it should be noted that the total cell production in the spinner flask cultures was 4.8 times higher than that in T-flask cultures. The total cell production in the spinner flask cultures was 5.2-fold higher than that in T-flask cultures. While the EV specific production (particles/cell) in T-flask cultures (4.40 ± 1.21 × 108 particles/mL, p < 0.05) was higher compared to spinner flask cultures (2.10 ± 0.04 × 108 particles/mL, p < 0.05), the spinner flask culture system offers scalability, making it capable of producing enough MSC-EV at a large scale for clinical applications. Therefore, we concluded that 3D culture system evaluated here serves as an efficient transitional platform that enables the scaling up of MSC-EV production for therapeutic purposes by utilizing stirred tank bioreactors and maintaining xeno-free conditions.

Cellular Therapy with Autologous Mesenchymal Stromal Cells in Patients with Drug Resistant Pulmonary Tuberculosis

The objective: to evaluate the effectiveness of treatment with autologous mesenchymal stromal cells (MSCs) in patients with drug resistant pulmonary tuberculosis (DR TB).Subjects and Methods. 120 patients with drug resistant tuberculosis aged 18 to 61 years old were enrolled in the study. They all were treated at the Republican Scientific and Practical Center of Pulmonology and Phthisiology from 2009 to 2018. Against the background of anti-tuberculosis treatment, patients (60 people) from Main Group (MG) underwent bone marrow sampling and then intravenous administration of autologous MSCs.Results. The average dose of administered cells was 1x106 per kg of the patient body weight. The average duration of MSC cultivation made 35 days. Treatment effectiveness in MG made 90% versus 71% in Control Group (CG). All patients who were successfully cured of tuberculosis (TB) using autologous MSCs had no tuberculosis relapses during 5 years of follow-up. In Control Group, 8 (19%) cases of relapse were reported. In Main Group versus Comparison Group, the rates indicating healing of cavities and absence of relapse are statistically significantly better.Conclusion. The use of autologous MSCs in patients with drug resistant tuberculosis has shown its high effectiveness.

Experimental study of transient particle suspension in bioreactors using a light attenuation technique

The culture of mesenchymal stromal cells relies on the use of suspended microcarriers as adhesion supports. During the particle suspension phases, the temporal evolution of the spatial distribution of particle concentrations is generally poorly characterized. In this study, the light attenuation technique was used to access this distribution and the duration of particle homogenization. Considering the minimal agitation rate Nref for which particle suspension was observed for all the microcarrier concentrations 〈C〉 studied, the results showed that using an agitation frequency close to Nref significantly increased the homogenization duration compared to N≃1.7×Nref. The transient microcarrier overconcentration was also determined locally. At N=Nref, the resuspension time was negatively impacted by 〈C〉, which also resulted in longer particle overconcentrations. A time-integral particle overconcentration term was considered to estimate the severity of inter-microcarrier collisions. The results suggested that increased agitation could limit time-cumulative overconcentrations beyond a particle concentration of 3 g/L.

Pre-treatment of granular osteoplastic material for improving the reparative regeneration of jaw bone defects

Aim – to develop a method for preliminary preparation of a granular osteoplastic material (GOM) for improving the quality of reparative osteogenesis of jaw bone defects that can be used in clinical setting.&#x0D; Material and methods. The in vitro study was performed using 9 samples (3 samples in each study group). Group 1 included intact samples of grafting material Cerabone (Botiss biomaterials GmbH, Germany). In group 2, the samples of Cerabone (Botiss biomaterials GmbH, Germany) were subject to degassing and dust extraction in two stages using the original method developed by the author. In group 3, a culture of mesenchymal-stromal cells (MSC) obtained from the human umbilical cord was used as a control. The developed method was assessed for cytotoxicity using human MSC. The proliferative index and cell doubling time were registered. A topographic analysis of the sample surface was performed using scanning electron microscopy. To assess the rate of degassing, the experiment included three replicates. The fluid volume was recorded every 2.5 minute. For statistical data processing, we used SPSS 25.0 software (IBM Corporation, Armonk, New York, USA).&#x0D; Results. In Group 2, that included the samples of GOM fractions with the preliminary degassing and dust extraction, we revealed a decreased content of coarse and fine fraction dust on the outer and inner surfaces of the pores and mouths of interpore channels and voids in all samples. The granular osteoplastic material prepared for the use by the method of degassing and dust extraction proved to have no toxic effect on the growth and viability of human mesenchymal-stromal cells.&#x0D; Conclusion. A preliminary preparation of GOM by the method of degassing and dust extraction developed by the author in clinical conditions ex tempore significantly optimizes the adsorption and drainage properties of the GOM fraction.

Effect of Silicone Rubber/Polyvinyl Alcohol /Zirconium Oxide Compound on Mesenchymal Stromal Cells

Objective: This study aimed to conduct a cytotoxicity test in determining the viability and proliferation profile for novel material of silicone rubber/polyvinyl alcohol (PVA) with or without Zirconium oxide on mesenchymal stromal cell culture. Methods: An in vitro study was carried out on adipose-derived mesenchymal stromal cell culture. Samples were divided into five groups: control, silicone rubber/polyvinyl alcohol (PVA) without Zirconium oxide, silicone rubber/polyvinyl alcohol (PVA) with Zirconium oxide 1 %, 3 %, and 5 %. Each group contained 2×105 seeded MSCs/well stained with MTT for its viability. For proliferation, MTT staining was performed on days 1, 3, and 5 to assess the trend of the percentage of the living cell. Statistical analysis was conducted using ANOVA, or the Kruskal-Walli’s test with a CI of 95%.

Local manufacturing processes contribute to variability in human mesenchymal stromal cell expansion while growth media supplements contribute to variability in gene expression and cell function: a Biomedical Excellence for Safer Transfusion (BEST) collaborative study

Background aimsCulture-derived mesenchymal stromal cells (MSCs) exhibit variable characteristics when manufactured using different methods, source material and culture media. The purpose of this multicenter study was to assess the impact on MSC expansion, gene expression and other characteristics when different laboratories expanded MSCs from cultures initiated with bone marrow−MSC aliquots derived from the same donor source material yet with different growth media. MethodsEight centers expanded MSCs using four human platelet lysate (HPL) and one fetal bovine serum (FBS) products as media supplements. The expanded cells were taken through two passages then assessed for cell count, viability, doubling time, immunophenotype, cell function, immunosuppression and gene expression. Results were analyzed by growth media and by center. ResultsCenter methodologies varied by their local seeding density, feeding regimen, inoculation density, base media and other growth media features (antibiotics, glutamine, serum). Doubling times were more dependent on center than on media supplements. Two centers had appropriate immunophenotyping showing all MSC cultures were positive for CD105, CD73, CD90 and negative for CD34, CD45, CD14, HLA-DR. MSCs cultured in media supplemented with FBS compared with HPL featured greater T-cell inhibition potential. Gene expression analysis showed greater impact of the type of media supplement (HPL versus FBS) than the manufacturing center. Specifically, nine genes were decreased in expression and six increased when combining the four HPL-grown MSCs versus FBS (false discovery rate [FDR] <0.01), however, without significant difference between different sources of HPL (FDR <0.01). ConclusionsLocal manufacturing process plays a critical role in MSC expansion while growth media may influence function and gene expression. All HPL and FBS products supported cell growth.

Extracellular Matrix Deposition Defines the Duration of Cell Sheet Assembly from Human Adipose-Derived MSC

Cell sheet (CS) engineering using mesenchymal stromal cells (MSC) draws significant interest for regenerative medicine and this approach translates to clinical use for numerous indications. However, little is known of factors that define the timing of CS assembly from primary cultures. This aspect is important for planning CS delivery in autologous and allogeneic modes of use. We used a comparative in vitro approach with primary donors’ (n = 14) adipose-derived MSCs and evaluated the impact of healthy subject’s sex, MSC culture features (population doubling time and lag-phase), and extracellular matrix (ECM) composition along with factors related to connective tissue formations (α-SMA and FAP-α) on CS assembly duration. Using qualitative and quantitative analysis methods, we found that, in seeded MSCs, high contents of collagen I and collagen IV had a direct correlation with longer CS assembly duration. We found that short lag-phase cultures faster turned to a ready-to-use CS, while age, sex, fibronectin, laminin, α-SMA, and FAP-α failed to provide a significant correlation with the timing of assembly. In detachable CSs, FAP-α was negatively correlated with the duration of assembly, suggesting that its concentration rose over time and contributed to MSC activation, transitioning to α-SMA-positive myofibroblasts and ECM turnover. Preliminary data on cell density and collagen I deposition suggested that the TGF-β1 signaling axis is of pivotal importance for ECM composition and construct maturation.

An Intravital Imaging Protocol to Visualize and Phenotype the Hematopoietic Niche of Clonal Hematopoiesis

Clonal Hematopoiesis of indeterminate potential (CHIP) is a condition where blood cells are produced from a few clones of hematopoietic stem cells (HSCs) carrying leukemia-associated driver mutations 1. Although selective pressures from low-grade inflammation of the bone marrow microenvironment have been shown to promote mutant cell expansion 2-7, we focus on the disease-initiating niche, which is defined as a subset of marrow cells surrounding rare HSCs. Indeed, as we have recently described, clonal expansion of acute myeloid leukemia and activated HSCs 8,9 was not uniform, and only occurred in a subset of marrow spaces harboring bone remodeling activities. To identify the disease-initiating niche for therapeutic targeting, we developed an intravital imaging protocol to visualize the rare pre-malignant clones in the minimally perturbed microenvironment and phenotype their niche. The standard practice to generate CHIP models relies on transplanting syngeneic or allogeneic cells into a sub-lethally irradiated recipient. However, concerns arise as irradiation compromises the microenvironment 10. Successful engraftment in non-conditioned mice can be achieved by injecting a high number of cells (1.5 x 10 7 cells) 11,12, but modeling early clonal expansion events from single cells remain challenging, as a crowd of cells is often observed in proximity. Here, we established a low dose (0.5-1.5 Gy), whole body or local irradiation regimen that preserves the integrity of the bone marrow microenvironment. We performed high-resolution in-vivo imaging to capture dynamics of single cells and cells undergoing early expansion. Specifically, as little as 0.5Gy irradiation enabled survival of the transplanted cells (2x10 6 GFP + healthy whole bone marrow) in non-irradiated side, and allowed direct visualization of early clonal expansion in vivo through 16 weeks . Engraftment was negligible in non-irradiated mice.Through in-vivo, video-rate tracking of Rhodamine dextran dye (70kDa) leakage from vessels into the extravascular space showed no increase in permeability 13 or signs of vessel dilation, suggesting minimal inflammation after the radiation insult (N= 3 mice, data points are individual vessel segments. Mann-Whitney U test). Preliminary findings with in-vitro cultures of mesenchymal stromal cells (MSCs) have also suggested that the MSCs retain their ability for tri-lineage differentiation after the low-dose irradiation. With this imaging protocol, we showed that hot spots of cell expansion exist in the Tet2 +/- murine model. To capture the highly localized niche factors responsible for these hot spots, we implemented image-guided live-cell labeling adapted from the previously published Image-seq protocols 9. As illustrated in Figure 1, a small channel is etched in the bone with plasma-mediated laser ablation. The micropipette was then inserted to the region of interest for delivery of fluorescent antibodies under image guidance. By administering FITC-conjugated anti-CD45 antibodies into the marrow cavities, we can label and recover ~10,000 live cells with 98% viability from two regions of interest, suitable for next generation single cell sequencing. The technique can be expanded to employ antibody cocktails to visualize and enrich particular cell lineages of interest during cell isolation, while preserving spatial information. Its compatibility with standard cell isolation protocols for FACS may help collect cellular targets that are geometrically inaccessible for cell aspiration. In conclusion, we established a working model to visualize expansion of healthy and Tet2 +/- hematopoietic cells in vivo. This can be followed by image-assisted live-cell tagging to isolate local microenvironment cells and study cell-niche coordination at high spatial precision. The imaging protocol may also be broadly applied to study microenvironment regulations in non-malignant clonal disorders.

Presence of Recurrent Somatic Mutations in Mesenchymal Stromal Cell Fractions Isolated from Acute Myeloid Leukemia As an Evidence of Clonality

Introduction: Acute myeloid leukemia (AML) involves somatic mutations in hematopoietic stem cells (HSCs). Recent evidence suggests the bone marrow microenvironment, particularly mesenchymal stromal cells (MSCs), also influences AML development. Abnormalities in MSCs from AML patients have been observed (von der Heide et al., 2016), potentially impacting leukemia progression. This study aims to identify MSC somatic mutations and their consequences, further exploring their role in AML. Understanding MSCs' impact on the leukemic microenvironment may shed light on AML pathophysiology and guide targeted therapies, particularly benefiting patients with adverse risk disease. Methods: A total of 28 bone marrow cases were collected from AML patients with adverse risk, including those with complex karyotype, monosomy karyotype, chromosome 5/7/17 abnormalities, TP53 mutation, or relapsed/refractory AML. From these cases, 14 paired MSC and leukemic cell (LC) fractions were analyzed and are presented here. Magnetic bead sorting was used to isolate CD33+ LCs, while the plastic adherence method was employed for MSC culture. Following magnetic isolation, CD33- cells were plated in DMEM-LG with FBS and pen/strep, and MSC colonies formed within 48 hours. Contaminating cells were removed through media changes, and passaging was performed at 70-80% confluency. Flow cytometry at passage 3 characterized MSCs based on cell surface expression of CD105, CD73, and CD90, in accordance with the ISCT guideline. DNA and RNA were extracted from MSCs at passage 3 and subjected to whole exome sequencing (WES) using the Illumina platform, along with the LC fractions. WES aimed for 200X depth for the paired DNA samples. A standard bioinformatics pipeline was used for sequence alignment and variant calling, with variants requiring sufficient read depth (≥30x) and variant allele frequency in the case (&amp;gt;5%) and in the control (&amp;lt;5%). Synonymous variants were filtered out, and gene ontology and pathway enrichment analyses explored the biological significance and potential involvement in leukemogenesis of the identified mutations. Whole transcriptomics for gene expression analyses was also conducted for both MSC and LC fractions. Results: In 14 analyzed cases, a total of 548 somatic variants were identified in the MSC fraction, affecting 480 genes, including 518 nonsynonymous single nucleotide variants (SNVs), 7 stop-gain SNVs, 1 stoploss, 1 non-frameshift insertion, 2 frameshift deletions, 1 frameshift insertion, and 2 non-frameshift deletions, with 16 unknown variants. The average read depth was 75 (range: 15 - 887), and the average variant allele frequency was 50% (range: 11% - 90%). On average, 38 genes were mutated per MSC case, with 8 genes detected in at least 3 cases, 25 in exactly 2 cases, and 447 genes found in only one case. In the leukemic fraction, 686 somatic variants in 595 genes were identified, with an average read depth of approximately 75 (range: 10 - 2596) and an average variant allele frequency of 47% (range: 8% - 85%). On average, 48 mutations were detected per leukemic case, with 12 mutations found in at least 3 cases, 40 in 2 cases, and 543 in only one case. Among the 14 cases, 10 cases (71%) had mutations in known driver genes for AML ( FLT3, NPM1, IDH1, IDH2, DNMT3A, RUNX1, TP53) exclusively in the leukemic fraction. As seen in Figure 1., of the 480 genes mutated in the MSC fraction, 69 overlapped with the 595 genes mutated in the leukemic fraction, while 411 genes were uniquely mutated in the MSC fraction. Further analysis is ongoing, and pathway analysis will be conducted once the remaining 14 cases are processed. Conclusions: This study identifies distinct somatic mutations in AML patients' MSC and leukemic cell fractions, revealing genomic complexity and crosstalk impacting leukemia progression. Understanding the functional implications of these mutations is crucial for unraveling their roles in leukemogenesis and developing personalized therapeutic interventions targeting MSC somatic mutations.

Poly(ethylene glycol)-Based Hydrogel Microcarriers Alter Secretory Activity of Genetically Modified Mesenchymal Stromal Cells.

In order to scale up culture therapeutic cells, such as mesenchymal stromal cells (MSCs), culture in suspension bioreactors using microcarriers (μCs) is preferred. However, the impact of microcarrier type on the resulting MSC secretory activity has not been investigated. In this study, two poly(ethylene glycol) hydrogel formulations with different swelling ratios (named "stiffer" and "softer") were fabricated as μC substrates to culture MSCs and MSCs genetically modified to express the interleukin-1 receptor antagonist (IL-1Ra-MSCs). Changes in cell number, secretory and angiogenic activity, and changes in MAPK signaling were evaluated when cultured on hydrogel μCs, as well as on tissue culture plastic-based Synthemax μCs. We demonstrated that culture on stiffer μCs increased secretion of IL-1Ra compared to culture on Synthemax μCs by IL-1Ra-MSCs by 1.2- to 1.6-fold, as well as their in vitro angiogenic activity, compared to culture on Synthemax μCs, while culture on both stiffer and softer μCs altered the secretion of several other factors compared to culture on Synthemax μCs. Changes in angiogenic activity corresponded with increased gene expression and secretion of hepatocyte growth factor by MSCs cultured on softer μCs by 2.5- to 6-fold compared to MSCs cultured on Synthemax μCs. Quantification of phosphoprotein signaling with the MAPK pathway revealed broad reduction of pathway activation by IL-1Ra-MSCs cultured on both stiffer and softer μCs compared to Synthemax, where phosphorylated c-Jun, ATF2, and MEK1 were reduced specifically on softer μCs. Overall, this study showed that μC surfaces can influence the secretory activity of genetically modified MSCs and identified associated changes in MAPK pathway signaling, which is a known central regulator of cytokine secretion.

Interaction between mesenchymal stromal cells and tuberculous mycobacteria in vitro

The objective: in an in vitro experiment, we compared phagocytic parameters of mesenchymal stromal cells (MSCs) and macrophages to tuberculous mycobacteria, assessed the ability of MSCs and macrophages to lyse mycobacteria or maintain their intracellular growth, their effect on formation of phenotypic drug resistance of mycobacteria, as well as the effect of tuberculous mycobacteria on the type of MSCs cell death.Subjects and Methods. Balb/c male mice, aged 6 to 8 weeks, were used in the experiment. Bone marrow MSCs were obtained from femurs and tibias by further cultivation, peritoneal macrophages were elicited with 4% alpha-glucan. The intracellular content of mycobacteria was counted using a confocal microscope with x 400 magnification. Susceptibility of mycobacteria to isoniazid and development of phenotypic drug resistance after culturing MSCs and macrophages with MTB on Lowenstein–Jensen medium was assessed by counting CFU. In 5 days after the infection, the number of apoptotic and necrotic MSCs and macrophages was determined by a flow cytometer.Results. On Day 1, the total number of phagocytosed MTB, as well as the number of phagocytic-active macrophages, exceeds the corresponding figures for MSCs more than twice. MSCs phagocytize tuberculous mycobacteria in a smaller amount, but MTB reproduces in them more actively: the number of CFU after 7 days of cell cultivation with MTB exceeded the corresponding parameter by almost 50 times after 24 hours of cultivation. In cultures of infected MSCs cultivated for 7 days, regardless of the presence of isoniazid, there was a rapid growth of tuberculous mycobacteria. On Day 5 after infection of macrophage culture with tuberculous mycobacteria, the number of necrotic cells was 2.7 times greater than that of uninfected necrotic macrophages, but the number of apototic cells in these groups differed slightly. In the culture of MSCs, there were 8.5 times more infected nectrotic cells versus uninfected necrotic MSCs, and the number of necrotic MSCs was 4.5 times higher than the number of MSCs with apoptosis, while in the culture of infected macrophages, the number of necrotic cells was the same as number of apoptotic cells. Unlike macrophages, treatment of MSCs with isoniazid did not inhibit the intracellular proliferation of MTB.Conclusion. MSCs have the ability to phagocytose mycobacteria, but they do it less actively than macrophages and, unlike macrophages, they are not able to restrain the reproduction of tuberculous mycobacteria. Mycobacteria have phenotypic drug resistance in MSCs. In MSCs, when infected with tuberculous mycobacteria, there is a pronounced shift towards necrosis in the type of cell death, which can lead to dissemination of MTB and development of local destructive changes.

Improving vasculoprotective effects of MSCs in coronary microvessels - benefits of 3D culture, sub-populations and heparin.

Opening occluded coronary arteries in patients with myocardial infarction (MI) damages the delicate coronary microvessels through a process called myocardial ischaemia-reperfusion injury. Although mesenchymal stromal cells (MSCs) have the potential to limit this injury, clinical success remains limited. This may be due to (i) poor MSC homing to the heart (ii) infused MSCs, even if derived from the same site, being a heterogeneous population with varying therapeutic efficacy and (iii) conventional 2D culture of MSCs decreasing their homing and beneficial properties. This study investigated whether 3D culture of two distinctly different bone marrow (BM)-derived MSC sub-populations could improve their homing and coronary vasculoprotective efficacy. Intravital imaging of the anaesthetised mouse beating heart was used to investigate the trafficking and microvascular protective effects of two clonally-derived BM-derived MSC lines, namely CD317neg MSCs-Y201 and CD317pos MSCs-Y202, cultured using conventional monolayer and 3D hanging drop methods. 3D culture consistently improved the adhesive behaviour of MSCs-Y201 to various substrates in vitro. However, it was their differential ability to reduce neutrophil events within the coronary capillaries and improve ventricular perfusion in vivo that was most remarkable. Moreover, dual therapy combined with heparin further improved the vasculoprotection afforded by 3D cultured MSCs-Y201 by also modifying platelet as well as neutrophil recruitment, which subsequently led to the greatest salvage of viable myocardium. Therapeutic benefit could mechanistically be explained by reductions in coronary endothelial oxidative stress and intercellular adhesion molecule-1 (ICAM-1)/vascular cell adhesion molecule-1 (VCAM-1) expression. However, since this was noted by both 2D and 3D cultured MSCs-Y201, therapeutic benefit is likely explained by the fact that 3D cultured MSCs-Y201 were the most potent sub-population at reducing serum levels of several pro-inflammatory cytokines. This novel study highlights the importance of not only 3D culture, but also of a specific CD317neg MSC sub-population, as being critical to realising their full coronary vasculoprotective potential in the injured heart. Since the smallest coronary blood vessels are increasingly recognised as a primary target of reperfusion injury, therapeutic interventions must be able to protect these delicate structures from inflammatory cells and maintain perfusion in the heart. We propose that relatively feasible technical modifications in a specific BM-derived MSC sub-population could achieve this.

Biological properties of macroporous cryostructurate based on extracellular matrix components

Objective: to study the biological properties of macroporous cryostructurate from multicomponent concentrated collagen-containing solution (MCCS) as a promising matrix for the formation of cell- and tissue-engineered constructs.Materials and methods. A macroporous spongy carrier was obtained by cryostructuring of collagencontaining extract, prepared by acetic acid hydrolysis of chicken connective tissue (BIOMIR Service, Russian Federation). N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide (Sigma-Aldrich, USA) was used to make the cryostructurate water insoluble. The micromorphology of the sponge surface was studied using scanning electron microscopy. The cytotoxicity of the carrier was evaluated by reaction of the mouse NIH 3T3 fibroblast cell culture using automated microscope IncuCyte ZOOM (EssenBioscience, USA). Biocompatibility of the macroporous carrier was studied on cultures of human adipose tissue-derived mesenchymal stromal cells (AD-MSC), human hepatocellular carcinoma cell line HepG2 and human umbilical vein endothelial cell line EA.hy926. The metabolic activity of cells was determined using PrestoBlue™ reagents (Invitrogen™, USA). Cell population development during long-term cultivation of the cell-engineered construct (CEC) was assessed by fluorescencelifetime imaging microscopy over the entire surface of the sample using a Leica Dmi8 inverted microscope with Leica Thunder software (Leica Microsystems, Germany).Results. Optical microscopy and scanning electron microscopy (SEM) showed the presence of pores of different sizes in the resulting biopolymer material: large pores with 237 ± 32 μm diameter, medium-sized pores with 169 ± 23 μm diameter, and small-sized pores with 70 ± 20 μm diameter; large and medium-sized pores were predominant. The studied media did not exhibit cytotoxicity. Cell adhesion and proliferation on the surface of the material and their penetration into the underlying layers during long-term cultivation were observed. The highest metabolic activity of the cells was observed for human AD-MSC on day 14, which corresponds to the normal dynamics of development of a population of cells of this type. The functional activity of HepG2 cells – albumin and urea production – was shown in the liver CEC model.Conclusion. The good adhesion and active proliferation that were shown for the three cell types indicate that the resulting biopolymer carrier is biocompatible, and that the spread of the cells into the inner volume of the sponge and active population of the sponge under prolonged culturing indicates that this material can be used to create cell- and tissue-engineered constructs.

MicroRNAs as prognostic markers for chondrogenic differentiation potential of equine mesenchymal stromal cells.

Mesenchymal stromal cells (MSCs) are a promising cell source for cartilage tissue regeneration in animals and humans but with large inter-donor variation in their in vitro chondrogenic differentiation potential. Underlying molecular mechanisms responsible for culture-expanded MSC heterogeneity remains poorly understood. In this study, we sought to identify variations in miRNA signatures associated with cultured equine MSC chondrogenic differentiation potential from different donors. Neocartilage tissue generated from equine cord blood-derived MSCs (CB-MSCs) was categorized as having either high or low chondrogenic potential based on their histological appearance and quantification of glycosaminoglycan deposition. Using next-generation sequencing, we identified 30 differentially expressed miRNAs amongst undifferentiated MSC cultures that corresponded with their chondrogenic potential. Of note, MSCs with low chondrogenic potential upregulated miR-146a and miR-487b-3p, which was also observed by qRT-PCR. Our findings suggest that miRNA profiling of equine MSC cultures may have prognostic value in selecting MSC donors with regards to their chondrogenic differentiation potential.

Heparin-collagen I bilayers stimulate FAK/ERK½ signaling via α2β1 integrin to support the growth and anti-inflammatory potency of mesenchymal stromal cells.

Understanding mesenchymal stromal cells (MSCs) growth mechanisms in response to surface chemistries is essential to optimize culture methods for high-quality and robust cell yields in cell manufacturing applications. Heparin (HEP) and collagen 1 (COL) substrates have been reported to enhance cell adhesion, growth, viability, and secretory potential in MSCs. However, the biomolecular mechanisms underlying the benefits of combined HEP/COL substrates are unknown. This work used HEP/COL bilayered surfaces to investigate the role of integrin-HEP interactions in the advantages of MSC culture. The layer-by-layer approach (LbL) was used to create HEP/COL bilayers, which were made up of stacks of 8 and 9 layers that combined HEP and COL in an alternate arrangement. Surface spectroscopic investigations and laser scanning microscopy evaluations verified the biochemical fingerprint of each component and a total stacked bilayer thickness of roughly 150 nm. Cell growth and apoptosis in response to IC50 and IC75 levels of BTT-3033 and Cilengitide, α2β1 and αvβ3 integrin inhibitors respectively, were evaluated on HEP/COL coated surfaces using two bone marrow-derived MSC donors. While integrin activity did not affect cell growth rates, it significantly affected cell adhesion and apoptosis on HEP/COL surfaces. HEP-ending HEP/COL surfaces significantly increased FAK-ERK½ phosphorylation and endogenous cell COL deposition compared to COL, COL-ending HEP/COL and uncoated surfaces. BTT-3033 but not Cilengitide treatment markedly affected FAK-ERK½ activity levels on HEP-ending HEP/COL surfaces supporting a major role for α2β1 activity. BTT-3033 treatment on HEP-ending bilayers reduced MSC-mediated macrophage inhibitory activity and altered the cytokine profile of co-cultures. Overall, this study supports a novel role for HEP in regulating the survival and potency of MSCs via enhancing the α2β1-FAK-ERK½ signaling mechanism.

Effect of pro-inflammatory cytokine priming and storage temperature of the mesenchymal stromal cell (MSC) secretome on equine articular chondrocytes.

Context: Osteoarthritis (OA) is an invalidating articular disease characterized by cartilage degradation and inflammatory events. In horses, OA is associated with up to 60% of lameness and leads to reduced animal welfare along with extensive economic losses; currently, there are no curative therapies to treat OA. The mesenchymal stromal cell (MSC) secretome exhibits anti-inflammatory properties, making it an attractive candidate for improving the management of OA. In this study, we determined the best storage conditions for conditioned media (CMs) and tested whether priming MSCs with cytokines can enhance the properties of the MSC secretome. Methods: First, properties of CMs collected from bone-marrow MSC cultures and stored at -80°C, -20°C, 4°C, 20°C or 37°C were assessed on 3D cultures of equine articular chondrocytes (eACs). Second, we primed MSCs with IL-1β, TNF-α or IFN-γ, and evaluated the MSC transcript levels of immunomodulatory effectors and growth factors. The primed CMs were also harvested for subsequent treatment of eACs, either cultured in monolayers or as 3D cell cultures. Finally, we evaluated the effect of CMs on the proliferation and the phenotype of eACs and the quality of the extracellular matrix of the neosynthesized cartilage. Results: CM storage at -80°C, -20°C, and 4°C improved collagen protein accumulation, cell proliferation and the downregulation of inflammation. The three cytokines chosen for the MSC priming influenced MSC immunomodulator gene expression, although each cytokine led to a different pattern of MSC immunomodulation. The cytokine-primed CM had no major effect on eAC proliferation, with IL-1β and TNF-α slightly increasing collagen (types IIB and I) accumulation in eAC 3D cultures (particularly with the CM derived from MSCs primed with IL-1β), and IFN-γ leading to a marked decrease. IL-1β-primed CMs resulted in increased eAC transcript levels of MMP1, MMP13 and HTRA1, whereas IFNγ-primed CMs decreased the levels of HTRA1 and MMP13. Conclusion: Although the three cytokines differentially affected the expression of immunomodulatory molecules, primed CMs induced a distinct effect on eACs according to the cytokine used for MSC priming. Different mechanisms seemed to be triggered by each priming cytokine, highlighting the need for further investigation. Nevertheless, this study demonstrates the potential of MSC-CMs for improving equine OA management.

Macromolecular crowding in equine bone marrow mesenchymal stromal cell cultures using single and double hyaluronic acid macromolecules

Macromolecular crowding (MMC) enhances and accelerates extracellular matrix (ECM) deposition in eukaryotic cell culture. Single hyaluronic acid (HA) molecules have not induced a notable increase in the amount and rate of deposited ECM. Thus, herein we assessed the physicochemical properties and biological consequences in equine bone marrow mesenchymal stromal cell cultures of single and mixed HA molecules and correlated them to the most widely used MMC agents, the FicollⓇ cocktail (FC) and carrageenan (CR). Dynamic light scattering analysis revealed that all HA cocktails had significantly higher hydrodynamic radius than the FC and CR; the FC and the 0.5 mg/ml 100 kDa and 500 kDa single HA molecules had the highest charge; and, in general, all molecules had high polydispersity index. Biological analyses revealed that none of the MMC agents affected cell morphology and basic cell functions; in general, CR outperformed all other macromolecules in collagen type I and V deposition; FC, the individual HA molecules and the HA cocktails outperformed CR in collagen type III deposition; FC outperformed CR and the individual HA molecules and the HA cocktails outperformed their constituent HA molecules in collagen type IV deposition; FC and certain HA cocktails outperformed CR and constituent HA molecules in collagen type VI deposition; and all individual HA molecules outperformed FC and CR and the HA cocktails outperformed their constituent HA molecules in laminin deposition. With respect to tri-lineage analysis, CR and HA enhanced chondrogenesis and osteogenesis, whilst FC enhanced adipogenesis. This work opens new avenues in mixed MMC in eukaryotic cell culture. Statement of significanceMixed macromolecular crowding (MMC) in eukaryotic cell culture is still under-investigated. Herein, single and double hyaluronic acid (HA) macromolecules, along with the traditional MMC agents FicollⓇ cocktail (FC) and carrageenan (CR), were used as MMC agents in equine mesenchymal stromal cell cultures. Biological analysis showed that none of the MMC agents affected cell morphology and basic cell functions. Protein deposition analysis made apparent that CR outperformed all other macromolecules in collagen type I and collagen type V deposition, whilst FC, the individual HA macromolecules and the HA cocktails outperformed CR in collagen type III deposition. Tri-lineage analysis revealed that CR and HA enhanced chondrogenesis and osteogenesis, whilst FC enhanced adipogenesis. These data illustrate that MMC agents are not inert macromolecules.