Mesenchymal Stromal Cells Cultures Research Articles

Efficient isolation and proliferation of human adipose-derived mesenchymal stromal cells in xeno-free conditions.

Classical methods used for culture of adipose-derived mesenchymal stromal cells (ADSCs) use xenobiotic components, which may present a potential risk for biological contamination and/or elicit immunological reactions. Therefore, the aim of this study was to establish a xeno-free methodology for the isolation and proliferation of human ADSCs (hADSCs). hADSCs were isolated by enzymatic digestion or mechanical dissociation and cultured in the presence of fetal bovine serum or human platelet lysate. Proliferation curves were performed as a function of time from the cell culture and used to calculate the population doubling time. Immunophenotyping and differentiation tests were used to identify and characterize the hADSCs. Human ADSCs isolated and cultured in conventional or xenobiotic-free conditions peaked at different days but achieved similar maximum proliferation. The hADSCs differentiation ability was similar in all groups. The characterization of hADSCs by flow cytometry showed low contamination of the cultures by other cell types. The xenobiotic-free methodology described in this study is a feasible and reproducible alternative for isolation and proliferation of hADSCs. This methodology is in accordance with the recommendations of the National Health Surveillance Agency, which proposes avoidance of xenobiotic products.

Recent advances in understanding mesenchymal stromal cells.

Mesenchymal stromal cells (MSCs) are among of the most studied cell type for cellular therapy thanks to the ease of isolation, cultivation, and the high ex vivo expansion potential. In 2018, the European Medicines Agency finally granted the first marketing authorization for an MSC product. Despite the numerous promising results in preclinical studies, translation into routine practice still lags behind: therapeutic benefits of MSCs are not as satisfactory in clinical trial settings as they appear to be in preclinical models. The bench-to-bedside-and-back approach and careful evaluation of discrepancies between preclinical and clinical results have provided valuable insights into critical components of MSC manufacturing, their mechanisms of action, and how to evaluate and quality-control them. We sum up these past developments in the introductory section (“Mesenchymal stromal cells: name follows function”). From the huge amount of information, we then selected a few examples to illustrate challenges and opportunities to improve MSCs for clinical purposes. These include tissue origin of MSCs, MSC culture conditions, immune compatibility, and route of application and dosing. Finally, we add some information on MSC mechanisms of action and translation into potency assays and give an outlook on future perspectives raising the question of whether the future clinical product may be cell-based or cell-derived.

Stem cells out of the bag: characterization of ex vivo expanded mesenchymal stromal cells for possible clinical use.

Aim:Mesenchymal stromal cells (MSC) are a promising tool for cellular therapy and regenerative medicine. One major difficulty in establishing a MSC expansion protocol is the large volume of bone marrow (BM) required. We studied whether cells trapped within a collection bag and filter system could be considered as a source of MSC.Results:From the 20 BM collection bag and filter systems, we recovered an average of 1.68 × 108 mononuclear cells, which is the equivalent to 60 ml of filtered BM. Mononuclear cells were expanded ex vivo to 17 × 106 MSC, with purity shown by a CD44+, CD105+, CD90+ and CD73+ immunophenotype, a reduction of 20% proliferating cells in a mixed lymphocyte reaction and also the ability of adipocyte differentiation.Conclusion:Long-term MSC cultures were established from the usually discarded BM collection bag and filter, maintaining an appropriate phenotype and function, being suitable for both investigation and clinical settings.

Aldehyde Dehydrogenase as a Marker of Early Mesenchymal Progenitor Cells in Donor Bone Marrow Stroma

Aim. To analyze the growth rate of mesenchymal stromal cell (MSC) culture depending on the aldehyde dehydrogenase-positive (ALDH+) cell count. Materials & Methods. The study involved bone marrow mesenchymal cell cultures of 10 donors (5 men and 5 women) with median age of 34.5 years (range 14-38 years). Nucleated cells were obtained by density gradient centrifugation. MSCs were cultivated according to the conventional protocol using platelet-rich donor plasma. Stromal cell identification and ALDH+ cell counting were performed by laser flow cytometry according to the criteria of the International Society for Cell Therapy. Results. The growth rate of MSC cultures and ALDH+ cell counts are maximum at primary and passage No. 1, becoming significantly lower by passage No. 3. The relationship between MSC culture growth rate and ALDH+ cell count was revealed. The older the donor, the lower MSC culture growth rate and ALDH+ cell count in bone marrow stroma. Conclusion. The data obtained indicate the relationship between bone marrow MSC culture growth rate, donor’s age, and ALDH+ cell count. ALDH-expressing cells proved to confer MSC population renewal. Based on the results acquired, we assume that the studied ALDH marker can serve as an objective criterion for placing mesenchymal cell elements into the category of early progenitor cells.

Monophosphoryl Lipid A and Retinoic Acid Combinations Increased Germ Cell Differentiation Markers Expression in Human Umbilical Cord-derived Mesenchymal Stromal Cells in an In vitro Ovine Acellular Testis Scaffold.

Infertility is known as one of the most common problems among couples. In this regard, generation of male germ cells from adult stem ones are among the current promising priorities of researchers. Mesenchymal stromal cells (MSCs) were previously induced to differentiate into germ-like progenitors in vitro. Monophosphoryl lipid A (MPLA) is a detoxified derivative of lipopolysaccharides (LPS) that lacks many of the endotoxic properties of LPS. Our present study aimed to investigate the expression of migration genes (CXCR4, VCAM1, VEGF, MMP2, and VLA4), and differentiation markers during human umbilical mesenchymal stromal cells (hUMSCs) culture in the presence of retinoic acid (RA) and MPLA-treated acellular testis. Accordingly, the high expression levels of deleted in azoospermia-like (DAZL), piwi-like RNA-mediated gene silencing 2 (PIWIL2) transcripts as well as protein were consequently observed in treated hUMSCs. It was concluded that combination treatment (i.e., MPLA/RA) had more prominent results than each of the treatments alone, even though MPLA and RA could be regarded as inducer of migration and differentiation, respectively. Ultimately, it was suggested to introduce the use of combination treatment as a more effective strategy to improve therapies in regenerative medicine.

Customized hydrogel substrates for serum-free expansion of functional hMSCs.

We describe a screening approach to identify customized substrates for serum-free human mesenchymal stromal cell (hMSC) culture. In particular, we combine a biomaterials screening approach with design of experiments (DOE) and multivariate analysis (MVA) to understand the effects of substrate stiffness, substrate adhesivity, and media composition on hMSC behavior in vitro. This approach enabled identification of poly(ethylene glycol)-based and integrin binding hydrogel substrate compositions that supported functional hMSC expansion in multiple serum-containing and serum-free media, as well as the expansion of MSCs from multiple, distinct sources. The identified substrates were compatible with standard thaw, seed, and harvest protocols. Finally, we used MVA on the screening data to reveal the importance of serum and substrate stiffness on hMSC expansion, highlighting the need for customized cell culture substrates in optimal hMSC biomanufacturing processes.

Design and characterisation of multi-functional strontium-gelatin nanocomposite bioinks with improved print fidelity and osteogenic capacity

3D bioprinting of constructs for tissue engineering and regenerative medicine has steadily gained attention due to its potential to fabricate anatomically-precise living constructs, localise specific cell types and enable the regeneration of functional tissues in a clinical setting. However, the limited availability of bioinks that can be successfully 3D bioprinted with high fidelity and simultaneously provide encapsulated cells with a tailored, low-stiffness microenvironment supporting functional tissue formation remains an unmet challenge. To address both the physical and biological limitations of available bioinks, this study aimed to develop a nanocomposite bioink (Sr-GelMA) comprising of strontium-carbonate (Sr) nanoparticles and low concentration (5 w/v%) gelatin-methacryloyl (GelMA) hydrogel for extrusion-based 3D bioprinting of low-stiffness cell-laden scaffolds with high shape fidelity and bone-specific cell signalling factors. We systematically investigated the effect of Sr incorporation on hydrogel physico-chemical properties, print fidelity, scaffold shape retention, as well as cell viability, osteogenic differentiation and in vitro bone formation. Nanocomposite Sr-GelMA hydrogels retained their physical and mechanical properties, while rheological studies revealed a significant increase in viscosity profiles that led to notably enhanced printability compared to GelMA alone. Moreover, bioprinted Sr-GelMA scaffolds exhibited excellent shape fidelity evidenced by a defined pore geometry on the x-y-z axis, resulting in an interconnected bioink filament and pore network that was maintained even after long-term culture and osteogenic differentiation (28 days) of human mesenchymal stromal cells (hMSCs). The presence of clustered Sr nanoparticles in the cell-laden bioink allowed high quality bioprinting combined with high hMSC viability (>95%) post-fabrication. Furthermore, Sr addition resulted in enhanced osteogenic differentiation of hMSCs as revealed by higher alkaline phosphatase (ALP) levels, osteocalcin (OCN) and collagen type-I (Col I) expression, with mineralised nodule formation distributed homogenously throughout the bioprinted construct. This study demonstrated that strontium-based nanocomposite bioinks optimised for extrusion-based 3D bioprinting of osteoconductive scaffolds support long-term shape retention with promising potential for bone tissue regeneration.

Comparison of the effectiveness of available sources of autologous colony-forming endothelial cells

Endothelial Colony-forming cells (ECFCs) are valuable material for tissue vascular engineering and cell therapy of ischemic tissues. Difficult isolation is the main problem for using of ECFCs. ECFCs isolation from peripheral blood and adipose tissue has been previously described. In the presented research we compared effectiveness of peripheral blood, subcutaneous and epicardial adipose tissue for the ECFCs isolation without cell sorting. ECFCs was isolated from peripheral blood, subcutaneous and epicardial adipose tissue obtained from coronary heart disease patients (males, n=8) undergoing elective coronary artery bypass surgery. The stromal-vascular fraction of subcutaneous (SVF-ST) and epicardial (SVF-ET) adipose tissue as well as the mononuclear blood fraction (MNF) were cultivated in the complied EGM-2 medium. Cell cultures phenotyping was performed by flow cytometry and confocal microscopy. Their angiogenic (Matrigel) and proliferative activity (xCELLigence analyzer) in vitro were studied. ECFCs were isolated from MNF in 50% of cases, from SVF-ST in 12.5% and SVF-ET in 37.5%. The proliferative activity of ECFCs isolated from adipose tissue was low while cultures from MNF showed high and medium activity in 75% of cases. Pure ECFCs (more 99%) were obtained from MNF to third passage without cell sorting. Cultures from adipose tissue were contaminated by mesenchymal-stromal cells (MSCs) and contained ECFCs and MSCs. Thus, peripheral blood is the most effective source of autologous ECFCs compared with adipose tissue for this isolation method. However, adipose tissue is a suitable source of MSC and mixed cultures of MSC and endothelial cells.

Influence of Bone Marrow Stromal and Leukemic Cells on Cytarabine Chemo-Toxicity in Acute Myeloid Leukemia (AML)

Mesenchymal stromal cells (MSC) are known to protect leukemic cells from drug-induced toxicity within the bone marrow (BM) niche, however, less is known about leukemic impact on supportive MSC. The nucleoside-analogue, cytarabine (Ara-C), is a front-line therapy for acute myeloid leukemia (AML), entering cells via the human equilibrative nucleoside transporter (hENT1). Over a third of AML patients do not show continued response to Ara-C-based regimens, with chemo-resistance linked with repressed hENT1 availability in some patients, while other mechanisms remain unknown. In addition to chemo-resistance, DNA damage caused by chemotherapeutics such as Ara-C can persist in BM-MSC, which remain of host origin following allogeneic stem cell transplantation. This genotoxicity hinders cellular functionality, and may be implicated in long-term hematopoietic failure and secondary malignancies. This study aimed to further elucidate chemo-resistance mechanisms, with particular focus on the contribution of leukemic cells to stromal cell toxicity; aiming to uncover potentially targetable features of resistant AML and reduce treatment burden on the BM. Primary MSC were isolated from BM aspirates from patients both at diagnosis and post-treatment; following ethical approval and informed consent. MSC cultures were confirmed by immunophenotype (flow cytometry) and differentiation capacity (cytological staining) and used in a similar manner to that of cell lines. AML (HL-60, K562) and stromal (HS-5) cell lines were mono- or co-cultured using trans-well inserts for 24h, prior to 1-24h treatment with 25µM Ara-C (equivalent to in vivo standard dose; 100-200mg/m2). Cytotoxicity was monitored by viability and proliferation (CFSE tracing) assays, and chemo-sensitivity assessed with a drug-efficacy screening tool (bacterial bioluminescent biosensor). Genotoxicity was determined by micronucleus and alkaline comet assays, assessing division abnormalities and DNA fragmentation respectively. Differential cytokine secretion utilised an array, with quantification by ELISA. In co-culture, stromal cells were sensitised to drug-induced cytotoxicity, while leukemic cells were themselves protected from treatment. Genotoxicity was also significantly increased in stromal cells (p=0.0397), while being significantly decreased in leukemic cells when co-cultured (p=0.0089), conferring with cytotoxicity findings. Similarly, BM-MSC from previously treated patients had significantly higher genotoxicity than patients at diagnosis (p=0.0138). While stromal cell proliferation remained unchanged regardless of intervention, data suggest increased proliferation in co-cultured leukemic cells compared to cells cultured alone. Chemo-sensitivity also increased in stromal cells in co-culture, while the opposite was seen for leukemic cells. Seven of 32 cytokines were differentially secreted by cell lines in co-culture compared to combined values from mono-cultured cells; CCL2, CXCL1, G-CSF, GM-CSF, IL-6, MIF and Serpin E1. Of these, the inflammatory cytokine MIF, macrophage migration inhibitory factor, was decreased in co-culture (p<0.0001), and has been implicated in the progression of other malignancies. Separation of cells following co-culture and treatment uncovered opposing MIF secretion profiles in cells with high (HL-60) and low (K562) sensitivity to Ara-C. Despite differential secretion, neither MIF, nor the MIF inhibitor ISO-1, had significant effects on chemo-sensitivity when cells were cultured in each condition for 24 hours. Chemo-resistance is evidently a network of complex, interlinking mechanisms which are not easily identified in vitro. MIF remains a likely candidate for studies into AML chemo-resistance, with research ongoing. This study shows for the first time that the co-culture of AML and MSC alters the genotoxic effect of chemotherapy. Future research utilising larger patient cohorts is required to fully understand how cells in the BM micro-environment can be targeted. This could potentially improve not only the overall outcome for AML patients, but reduce the cytotoxic and long-term genotoxic complications of current therapies. Disclosures No relevant conflicts of interest to declare.

TGF-β Signaling Contributes to Myelofibrosis and Clonal Dominance of Myeloproliferative Neoplasms

TGF-β expression is elevated in most cases of myeloproliferative neoplasms (MPNs). However, the contribution of TGF-β to disease pathogenesis is not well understood. Prior studies have shown that TGF-β regulates hematopoietic stem cell (HSC) quiescence. There also is published evidence that increased TGF-β may contribute to myelofibrosis. However, this is controversial, as recent studies have implicated other inflammatory cytokines in the development of myelofibrosis. Here, we test two specific hypotheses. First, we hypothesize that increased TGF-β signaling in mesenchymal stromal cells (MSCs) is required for the development of myelofibrosis. Second, we hypothesize that Jak2 mutated HSCs are resistant to the growth suppressive effect of TGF-β, resulting in a competitive advantage that contributes to their clonal expansion in MPN and clonal hematopoiesis. To test the first hypothesis, we abrogated TGF-β signaling in mesenchymal stem/progenitor cells by deleting Tgfbr2 using a doxycycline-repressible Osterix-Cre transgene (Osx-Cre), which targets all mesenchymal stromal cells in the bone marrow. Osx-Cre was induced at birth (by removal of doxycycline), since we recently reported that the post-natal loss of TGF-β signaling in mesenchymal stromal cells has no discernible effect on basal hematopoiesis or the stem cell niche. We transplanted bone marrow cells from UBC-CreERT2; Jak2V617F mice or c-kit+ cells transduced with MPLW515L retrovirus into irradiated wildtype or Osx-Cre; Tgfbr2f/fmice. For the Jak2V617F model, mice were treated with tamoxifen 6 weeks post transplantation to induce mutant Jak2 expression. Of note, elevated Tgfb1 was present in both MPN models. MPLW515L induced a rapidly fatal MPN with reticulin fibrosis in the bone marrow. A similar hematopoietic phenotype was observed in Osx-Cre; Tgfbr2f/f recipients. However, myelofibrosis, as measured by reticulin staining and Collagen III (Col3a1) mRNA expression, was reduced, but not completely abrogated in Osx-Cre; Tgfbr2f/fmice. Likewise, in the Jak2V617F MPN model, the hematopoietic phenotype was similar in wildtype and Osx-Cre; Tgfbr2f/fmice. Although overt myelofibrosis was not observed in this MPN model, increased RNA and protein expression of Collagen III were detected in the bone marrow. Although still above baseline, Col3a1 expression was significantly reduced in Osx-Cre; Tgfbr2f/frecipient mice. To examine the role of canonical TGF-β signaling in the induction of myelofibrosis, we cultured bone marrow derived MSCs from wildtype and Osx-Cre; Smad4f/f mice, in which canonical TGF-β signaling is abrogated. Treatment of wildtype MSC cultures with TGF-β1 induced the expression of fibrosis associated genes, including Col1a1 and Acta2, and down-regulated expression of key niche factors, including Cxcl12, Scf, and Bglap. Surprisingly, TGF-β1-induced expression of Col1a1 was intact in Smad4-deleted MSC cultures. Conversely, treatment of wildtype MSC cultures with the JNK inhibitor SP600125 abrogated TGF-β1-induced expression of Col1a1. Collectively, these data suggest that TGF-β signaling in MSCs contributes to the development of myelofibrosis in MPN through activation of the non-canonical JNK pathway. To test the second hypothesis, we set up a competitive transplantation assays using wildtype and Jak2V617F hematopoietic cells in which Tgfbr2 had been deleted to abrogate TGF-β signaling in HSCs. Specifically, we transplanted UBC-CreERT2; Jak2V617F; Tgfbr2f/f and UBC-CreERT2; Tgfbr2f/f bone marrow cells at 1:5 ratio into lethally irradiated wild type recipients. For control, we transplanted a 1:5 ratio of UBC-CreERT2; Jak2V617F to wild type cells. Mice were treated with tamoxifen to activate Cre expression 6 weeks post transplantation. Complete blood counts and donor chimerism were measured 6, 10, 14 and 18 weeks after tamoxifen. As expected, in the control group, donor chimerism with Jak2 mutated cells increased over time in myeloid lineages. In contrast, in the Tgfbr2-deleted group, no expansion of Jak2 mutated cells was observed. These data support our hypothesis that Jak2 mutated HSCs are resistant to the growth suppressive effect of TGF-β, providing a selective advantage that contributes to their clonal expansion in MPN and possibly clonal hematopoiesis. Disclosures No relevant conflicts of interest to declare.

Enhancement of Cellular Adhesion and Proliferation in Human Mesenchymal Stromal Cells by the Direct Addition of Recombinant Collagen I Peptide to the Culture Medium.

Mesenchymal stromal cells (MSCs) have considerable potential for a wide range of clinical applications and regenerative medicine and cell therapy. As a consequence, there is considerable interest in developing robust culture methods for producing large number of MSCs for use in repair of injured tissues or treatment of diseases. In general, tissue culture plates or flasks that have been precoated with substrates derived from animal tissues are used in the production of MSCs. However, these substrates can potentially cause serious problems due to contamination of the MSCs with animal-derived components. In this study, we evaluated the use of a type I collagen-based recombinant peptide (RCP) for MSC culture in an attempt to avoid the problems associated with animal cell-derived substances. This RCP is xeno free, has an increased RGD (Arg–Gly–Asp) sequence, and has high molecular weight uniformity. The effect of RCP on promotion of cellular adhesion and proliferation of MSCs was investigated in cultures in which RCP was included in the culture medium. The effects of RCP on promotion of cellular adhesion and proliferation of MSCs were investigated by comparing cultures in which the additive was present in the culture medium and those where the culture plates were coated with RCP. In addition, changes in gene expression profiles during cell culture were monitored by real time-polymerase chain reaction. Our analyses showed that RCP enhanced cellular adhesion and proliferation in cultures in which the additive was included in the culture medium. Our findings indicate that adding RCP to the culture medium could save time and cost in MSC culture. Our gene expression analysis indicated that RCP enhanced expression of genes encoding proteins associated with the extracellular matrix and cell adhesion.

Human Mesenchymal Stromal Cell-Derived Extracellular Vesicles Improve Liver Regeneration After Ischemia Reperfusion Injury in Mice.

Hepatic ischemia reperfusion injury (IRI) remains a major obstacle in liver resection and transplantation surgery, especially in diseased organs. Human mesenchymal stromal cells (MSCs) are reported to acutely alleviate hepatic IRI in mice by releasing bioactive membrane-enclosed extracellular vesicles (EVs), but the long-term effects of MSC-derived EV on hepatic IRI are unknown. Given the considerable differentiation capacity of fibroblasts (FBs) during wound healing and their morphological similarities with MSC, the present study aimed to investigate the potential of these two cell types and their cell-derived EV in attenuating liver damage after IRI. EVs were isolated and purified from the supernatant of MSC and FB cultures and, subsequently, characterized by electron microscopy, nanoparticle tracking analysis, and western blot. Liver injury and organ regeneration in a murine in vivo model of IRI were assessed by serum transaminase levels, histopathology, and immunohistochemistry. Changes in expression of inflammation-associated genes within liver tissue were evaluated by reverse transcriptase quantitative polymerase chain reaction. MSC, MSC-derived EV, FB, and FB-derived EV were systemically administered before hepatic IRI. We found that MSC and MSC-derived EV decreased serum transaminase levels, reduced hepatic necrosis, increased the amount of Ki67-positive hepatocytes, and repressed the transcription of inflammation-associated genes. Although they had no impact on organ damage, FB and FB-derived EV showed some regenerative potential in the late phase of hepatic IRI. Compared to FB, MSC and their derived EV had a stronger potential to attenuate liver damage and improve organ regeneration after hepatic IRI. These results suggest that the key therapeutic factors are located within EV.

Macromolecular dextran sulfate facilitates extracellular matrix deposition by electrostatic interaction independent from a macromolecular crowding effect.

A faithful reconstruction of the native cellular microenvironment is instrumental for tissue engineering. Macromolecular crowding (MMC) empowers cells to deposit their own extracellular matrix (ECM) in greater amounts, and thus contributes to building tissue-specific complex microenvironments in vitro. Dextran sulfate (DxS, 500 kDa), a semi-synthetic sulfated polyglucose, was shown previously at a fractional volume occupancy (FVO) of 5.2% (v/v; 100 μg/ml) to act as a potent molecular crowding agent in vitro. When added to human mesenchymal stromal cell (MSC) cultures, DxS enhanced fibronectin and collagen I deposition several-fold also at concentrations with negligible FVO (<1% v/v). In a cell-free system, incubation of culture media supplemented with fetal bovine serum (FBS), purified fibronectin or collagen I with DxS led to a co-deposition of respective components, exhibiting a similar granular pattern as observed in cell culture. Aggregation of FBS components, fibronectin or collagen I with DxS was confirmed by dynamic light scattering, where an increase in hydrodynamic radius in the respective mixtures was observed. FBS- and fibronectin aggregates could be dissociated with increasing salt concentrations, indicating electrostatic forces to be responsible for the aggregation. Conversely, collagen I-DxS aggregates increased in size with increasing ion concentration, likely caused by charge screening of collagen I, which is net negatively charged at neutral pH, thus permitting weaker intermolecular interactions to occur. The incorporation of DxS into the ECM resulted in altered ECM topography and stiffness. DxS-supplemented cultures exhibited potentiated bioactivity, such as enhanced adipogenic and especially osteogenic differentiation under inductive conditions. We propose an alternative mechanism by which DxS drives ECM deposition via aggregation, and in an independent manner from MMC. A deeper understanding of the underlying mechanism will enable optimized engineering approaches for ECM-rich tissue constructs.

Optically Transparent Anionic Nanofibrillar Cellulose Is Cytocompatible with Human Adipose Tissue-Derived Stem Cells and Allows Simple Imaging in 3D.

The anti-inflammatory and immunomodulatory properties of human mesenchymal stromal cells (MSCs) are a focus within regenerative medicine. However, 2D cultivation of MSCs for extended periods results in abnormal cell polarity, chromosomal changes, reduction in viability, and altered differentiation potential. As an alternative, various 3D hydrogels have been developed which mimic the endogenous niche of MSCs. Nevertheless, imaging cells embedded within 3D hydrogels often suffers from low signal-to-noise ratios which can be at least partly attributed to the high light absorbance and light scattering of the hydrogels in the visible light spectrum. In this study, human adipose tissue-derived MSCs (ADSCs) are cultivated within an anionic nanofibrillar cellulose (aNFC) hydrogel. It is demonstrated that aNFC forms nanofibres arranged as a porous network with low light absorbance in the visible spectrum. Moreover, it is shown that aNFC is cytocompatible, allowing for MSC proliferation, maintaining cell viability and multilineage differentiation potential. Finally, aNFC is compatible with scanning electron microscopy (SEM) and light microscopy including the application of conventional dyes, fluorescent probes, indirect immunocytochemistry, and calcium imaging. Overall, the results indicate that aNFC represents a promising 3D material for the expansion of MSCs whilst allowing detailed examination of cell morphology and cellular behaviour.

Secretion of Hematopoietic Niche Signal Molecules under Conditions of Osteogenic Differentiation of Multipotent Mesenchymal Stromal Cells Induced By Relief Calcium Phosphate Coating

Using a multiplex kit the secretion of a number of cytokines, chemokines, and growth factors has been investigated in vitro in a culture of human adipose-derived multipotent mesenchymal stromal cells (hAMMSCs) under conditions of their osteogenic differentiation caused by 14-day contact with a calcium phosphate (CP) surface of different roughness. Bilateral X-ray amorphous CP coatings were prepared on the samples of commercially pure titanium in the anodal regime using a microarc method. The electrolyte consisted of aqueous orthophosphoric acid (20 wt %), calcium carbonate (9 wt %), and synthetic hydroxyapatite nanopowder (6 wt %, particle diameter of 10–30 nm with single agglomerates up to 100 nm). hAMMSCs isolated from lipoaspirate were co-cultured after 4 passages with the CP-coated samples at a final concentration of 1.5 × 105 viable karyocytes per 1.5 mL of standard nutrition medium (without osteogenic stimulators) for 14 days (determination of the [CD45,34,14,20], CD73, CD90, and CD105 cell immunophenotype; analysis of secretory activity) and 21 days (alizarin red S cell culture staining) with medium replacement every 3–4 days. Under conditions of in vitro contact with rough CP coating hAMMSCs differentiated into osteoblasts synthesizing the mineralized bone matrix; this was accompanied by a 2−3-fold increase in the proportion of [CD45,34,14,20]+ hemopoietic cells. The following humoral factors of hemopoietic niches acted as the signal molecules escalating in vitro the hemopoietic base in 14 days of differentiating three-dimensional culture of hAMMSCs: leukemia inhibitory factor (LIF) and stem cell factor (SCF) cytokines in the case of the mean index of CP roughness Ra = 2.4–2.6 µm or stromal derived factor-1 (SDF-1α, CXCL12 chemokine) in the case of Ra = 3.1–4.4 µm.

Rapid Diels-Alder Cross-linking of Cell Encapsulating Hydrogels.

Recent efforts in the design of hydrogel biomaterials have focused on better mimicking the native cellular microenvironment to direct cell fate. To simultaneously control multiple material parameters, several orthogonal chemistries may be needed. However, present strategies to prepare cell-encapsulating hydrogels make use of relatively few chemical reactions. To expand this chemical toolkit, we report the preparation of hydrogels based on a Diels-Alder reaction between fulvenes and maleimides with markedly improved gelation kinetics and hydrolytic stability. Fulvene-maleimide gels cross-link up to 10-times faster than other commonly used DA reaction pairs and remain stable for months under physiological conditions. Furthermore, fulvene-maleimide gels presenting relevant biochemical cues, such as cell-adhesive ligands and proteolytic degradability, support the culture of human mesenchymal stromal cells. Finally, this rapid DA reaction was combined with an orthogonal click reaction to demonstrate how the use of selective chemistries can provide new avenues to incorporate multiple functionalities in hydrogel materials.

Molecular Profiles of Cell-to-Cell Variation in the Regenerative Potential of Mesenchymal Stromal Cells.

Cell-to-cell variation in the regenerative potential of mesenchymal stromal cells (MSCs) impedes the translation of MSC therapies into clinical practice. Cellular heterogeneity is ubiquitous across MSC cultures from different species and tissues. This review highlights advances to elucidate molecular profiles that identify cell subsets with specific regenerative properties in heterogeneous MSC cultures. Cell surface markers and global signatures are presented for proliferation and differentiation potential, as well as immunomodulation and trophic properties. Key knowledge gaps are discussed as potential areas of future research. Molecular profiles of MSC heterogeneity have the potential to enable unprecedented control over the regenerative potential of MSC therapies through the discovery of new molecular targets and as quality attributes to develop robust and reproducible biomanufacturing processes. These advances would have a positive impact on the nascent field of MSC therapeutics by accelerating the development of therapies with more consistent and effective treatment outcomes.

Preparing for cell culture scale-out: establishing parity of bioreactor- and flask-expanded mesenchymal stromal cell cultures

BackgroundCell-based therapies have the potential to become treatment options for many diseases, but efficient scale-out of these therapies has proven to be a major hurdle. Bioreactors can be used to overcome this hurdle, but changing the culture method can introduce unwanted changes to the cell product. Therefore, it is important to establish parity between products generated using traditional methods versus those generated using a bioreactor.MethodsMesenchymal stromal cells (MSCs) are cultured in parallel using either traditional culture flasks, spinner vessels or a new bioreactor system. To investigate parity between the cells obtained from different methods, harvested cells are compared in terms of yield, phenotype and functionality.ResultsBioreactor-based expansion yielded high cell numbers (222–510 million cells). Highest cell expansion was observed upon culture in flasks [average 5.0 population doublings (PDL)], followed by bioreactor (4.0 PDL) and spinner flasks (3.3 PDL). Flow cytometry confirmed MSC identity (CD73+, CD90+ and CD105+) and lack of contaminating hematopoietic cell populations. Cultured MSCs did not display genetic aberrations and no difference in differentiation and immunomodulatory capacity was observed between culture conditions. The response to IFNγ stimulation was similar for cells obtained from all culture conditions, as was the capacity to inhibit T cell proliferation.ConclusionsThe new bioreactor technology can be used to culture large amounts of cells with characteristics equivalent to those cultured using traditional, flask based, methods.

Potential Marker Genes for Predicting Adipogenic Differentiation of Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) are a promising source for tissue engineering of soft connective tissues. However, the differentiation capacity of MSCs varies among individual cell lines. Here, we show marker genes to predict the adipogenic potential of MSCs. To clarify the correlation between gene expression patterns before adipogenic induction and the differentiation level of MSCs after differentiation, we compared mRNA levels of 95 genes and glycerol-3-phosphate dehydrogenase (GPDH) activities in 15 MSC lines (five jaw and 10 ilium MSCs) from 15 donors. Expression profiles of 22 genes before differentiation significantly correlated with GPDH activities after differentiation. Expression levels of 11 out of the 22 genes in highly potent ilium MSCs were at least three times higher compared with jaw MSCs, which have limited differentiation potential. Furthermore, three-dimensional scatter plot for mRNA expression of ITGA5, CDKN2D, and CD74 could completely distinguish highly potent MSCs from poorly potent MSCs for adipogenesis. The treatment of MSC cultures with the anti-ITGA5 antibody reduced adipogenic differentiation of MSCs. Collectively, these results suggest that the three genes play a role in adipogenesis before induction and can serve as predictors to select potent MSCs for adipogenic differentiation.

Quantification of chondrogenic differentiation in monolayer cultures of mesenchymal stromal cells

Determining inhibitory or supportive effects of biological, chemical or physical factors on cell fates, including chondrogenic differentiation of mesenchymal stromal cells (MSCs), requires quantification techniques that are rapid, reproducible, and able to monitor these effects over time. Methods currently used to analyze chondrogenic differentiation are either qualitative staining procedures or indirect DNA quantifications. Because of these limitations, further methods are needed to improve determination of chondrogenic differentiation. In the present study, we applied a histological staining method, which is established for investigation of articular cartilage degeneration by use of Safranin O dye, on chondrogenic differentiated cells in monolayer cultures. MSCs were differentiated on 12-well formats, at increasing concentrations of TGF-β3, cell numbers, and incubation times. Quantification was performed by solubilizing the adsorbed dye into isopropanol followed by determining the optical density (O.D.) through spectrophotometry. Our results show that the O.D. is directly related to cell numbers and incubation periods, and that the technique is applicable to study agents which affect chondrogenic differentiation.