Cultivation in Human Serum Reduces Adipose Tissue-Derived Mesenchymal Stromal Cell Adhesion to Laminin and Endothelium and Reduces Capillary Entrapment

Automated Manufacturing Processes and Platforms for Large-scale Production of Clinical-grade Mesenchymal Stem/ Stromal Cells

Mesenchymal stem/stromal cells (MSCs) hold immense potential for regenerative medicine due to their remarkable regenerative and immunomodulatory properties. However, their therapeutic application requires large-scale production under stringent regulatory standards and Good Manufacturing Practice (GMP) guidelines, presenting significant challenges. This review comprehensively evaluates automated manufacturing processes and platforms for the scalable production of clinical-grade MSCs. Various large-scale culture vessels, including multilayer flasks and bioreactors, are analyzed for their efficacy in MSCs expansion. Furthermore, automated MSCs production platforms, such as Quantum® Cell Expansion System, CliniMACS Prodigy®, NANT001/ XL, CellQualia™, Cocoon® Platform, and Xuri™ Cell Expansion System W25 are reviewed and compared as well. We also underscore the importance of optimizing culture media specifically emphasizing the shift from fetal bovine serum to humanized or serum-free alternatives to meet GMP standards. Moreover, advances in alternative cryopreservation methods and controlled-rate freezing systems, that offer promising improvements in MSCs preservation, are discussed as well. In conclusion, advancing automated manufacturing processes and platforms is essential for realizing the full potential of MSCs-based regenerative medicine and accomplishing the increasing demand for cell-based therapies. Collaborative initiatives involving industry, academia, and regulatory bodies are emphasized to accelerate the translation of MSCs-based therapies into clinical practice.

Better isolation, proliferation and differentiation of human adipose-derived mesenchymal stem cells using human serum

Mesenchymal stem cells have many applications in medicine. Attention to the proliferation and differentiation of stem cell differentiation is an important issue. The aim of this study was to investigate the possibility of optimal isolation, proliferation, and differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) using human serum. Human serum (HS) was obtained from the venous blood of eight healthy individuals. The rate of proliferation and differentiation of ADSCs and expression of surface markers was assessed by flow cytometry. Bone differentiation was assessed using Alizarin Red staining. Data were analyzed using statistical software. Over time, HS showed more proliferation than fetal bovine serum (FBS) -enriched cells (p <0.05). Differentiation of ADSCs cells ls in HS-enriched medium is faster and more pronounced than differentiation in the control group. The expression of surface markers in the medium containing HS was the same as the medium containing FBS where the expression levels of CD105 and CD95 were found to be positive and the expression of CD34 and CD45 was negative. Due to the better proliferation of adipose tissue-derived mesenchymal cells in the medium containing HS than FBS, it is suggested that human serum be used in future clinical studies. Also, HS is healthier, safer, more accessible, and more affordable than FBS.

Case Studies Exemplifying the Transition to Animal Component-free Cell Culture

Cell culture techniques are strongly connected with modern scientific laboratories and production facilities. Thus, choosing the most suitable medium for the cells involved is vital, not only directly to optimise cell viability but also indirectly to maximise the reliability of the experiments performed with the cells. Fetal bovine or calf serum (FBS or FCS, respectively) is the most commonly used cell culture medium supplement, providing various nutritional factors and macromolecules essential for cell growth. Yet, the use of FBS encompasses a number of disadvantages. Scientifically, one of the most severe disadvantages is the lot-to-lot variability of animal sera that hampers reproducibility. Therefore, transitioning from the use of these ill-defined, component-variable, inconsistent, xenogenic, ethically questionable and even potentially infectious media supplements, is key to achieving better data reproducibility and thus better science. To demonstrate that the transition to animal component-free cell culture is possible and achievable, we highlight three different scenarios and provide some case studies of each, namely: i) the adaptation of single cell lines to animal component-free culture conditions by the replacement of FBS and trypsin; ii) the adaptation of multicellular models to FBS-free conditions; and (iii) the replacement of FBS with human platelet lysate (hPL) for the generation of primary stem/stromal cell cultures for clinical purposes. By highlighting these examples, we aim to foster and support the global movement towards more consistent science and provide evidence that it is indeed possible to step out of the currently smouldering scientific reproducibility crisis.

Transcriptomic heterogeneity of cultured ADSCs corresponds to embolic risk in the host

Stem cell therapy emerges as an effective approach for treating various currently untreatable diseases. However, fatal and unknown risks caused by their systemic use remain to be a major obstacle to clinical application. We developed a functional single-cell RNA sequencing (scRNA-seq) procedure and identified that transcriptomic heterogeneity of adipose-derived stromal cells (ADSCs) in cultures is responsible for a fatal embolic risk of these cells in the host. The pro-embolic subpopulation of ADSCs in cultures was sorted by gene set enrichment analysis (GSEA) and verified by a supervised machine learning analysis. A mathematical model was developed and validated for the prediction of embolic risk of cultured ADSCs in animal models and further confirmed by its application to public data. Importantly, modification of culture conditions prevented the embolic risk. This novel procedure can be applied to other aspects of risk assessment and would help further the development of stem cell clinical applications.

Potential Therapeutic Effects of Long-Term Stem Cell Administration: Impact on the Gene Profile and Kidney Function of PKD/Mhm (Cy/+) Rats

Cystic kidney disease (CKD) is a heterogeneous group of genetic disorders and one of the most common causes of end-stage renal disease. Here, we investigate the potential effects of long-term human stem cell treatment on kidney function and the gene expression profile of PKD/Mhm (Cy/+) rats. Human adipose-derived stromal cells (ASC) and human skin-derived ABCB5⁺ stromal cells (2 × 10⁶) were infused intravenously or intraperitoneally monthly, over 6 months. Additionally, ASC and ABCB5⁺-derived conditioned media were administrated intraperitoneally. The gene expression profile results showed a significant reprogramming of metabolism-related pathways along with downregulation of the cAMP, NF-kB and apoptosis pathways. During the experimental period, we measured the principal renal parameters as well as renal function using an innovative non-invasive transcutaneous device. All together, these analyses show a moderate amelioration of renal function in the ABCB5⁺ and ASC-treated groups. Additionally, ABCB5⁺ and ASC-derived conditioned media treatments lead to milder but still promising improvements. Even though further analyses have to be performed, the preliminary results obtained in this study can lay the foundations for a novel therapeutic approach with the application of cell-based therapy in CKD.

Modulating endothelial adhesion and migration impacts stem cell therapies efficacy

BACKGROUND

Limited knowledge of stem cell therapies` mechanisms of action hampers their sustainable implementation into the clinic. Specifically, the interactions of transplanted stem cells with the host vasculature and its implications for their therapeutic efficacy are not elucidated. We tested whether adhesion receptors and chemokine receptors on stem cells can be functionally modulated, and consequently if such modulation may substantially affect therapeutically relevant stem cell interactions with the host endothelium.

METHODS

We investigated the effects of cationic molecule polyethylenimine (PEI) treatment with or without nanoparticles on the functions of adhesion receptors and chemokine receptors of human bone marrow-derived Mesenchymal Stem Cells (MSC). Analyses included MSC functions in vitro, as well as homing and therapeutic efficacy in rodent models of central nervous system´s pathologies in vivo.

FINDINGS

PEI treatment did not affect viability, immunomodulation or differentiation potential of MSC, but increased the CCR4 expression and functionally blocked their adhesion receptors, thus decreasing their adhesion capacity in vitro. Intravenously applied in a rat model of brain injury, the homing rate of PEI-MSC in the brain was highly increased with decreased numbers of adherent PEI-MSC in the lung vasculature. Moreover, in comparison to untreated MSC, PEI-MSC featured increased tumour directed migration in a mouse glioblastoma model, and superior therapeutic efficacy in a murine model of stroke.

INTERPRETATION

Balanced stem cell adhesion and migration in different parts of the vasculature and tissues together with the local microenvironment impacts their therapeutic efficacy.

FUNDING

Robert Bosch Stiftung, IZEPHA grant, EU grant 7 FP Health.

Pro-angiogenic Activity Discriminates Human Adipose-Derived Stromal Cells From Retinal Pericytes: Considerations for Cell-Based Therapy of Diabetic Retinopathy

Diabetic retinopathy (DR) is a frequent diabetes-associated complication. Pericyte dropout can cause increased vascular permeability and contribute to vascular occlusion. Adipose-derived stromal cells (ASC) have been suggested to replace pericytes and restore microvascular support as potential therapy of DR. In models of DR, ASC not only generated a cytoprotective and reparative environment by the secretion of trophic factors but also engrafted and integrated into the retina in a pericyte-like fashion. The aim of this study was to compare the pro-angiogenic features of human ASC and human retinal microvascular pericytes (HRMVPC) in vitro. The proliferation and the expression of ASC and HRMVPC markers were compared. Adhesion to high glucose-conditioned endothelial extracellular matrix, mimicking the diabetic microenvironment, was measured. The angiogenesis-promoting features of both cell types and their conditioned media on human retinal endothelial cells (EC) were assessed. To identify a molecular basis for the observed differences, gene expression profiling was performed using whole-genome microarrays, and data were validated using PCR arrays and flow cytometry. Based on multiplex cytokine results, functional studies on selected growth factors were performed to assess their role in angiogenic support. Despite a distinct heterogeneity in ASC and HRMVPC cultures with an overlap of expressed markers, ASC differed functionally from HRMVPC. Most importantly, the pro-angiogenic activity was solely featured by ASC, whereas HRMVPC actively suppressed vascular network formation. HRMVPC, in contrast to ASC, showed impaired adhesion and proliferation on the high glucose-conditioned endothelial extracellular matrix. These data were supported by gene expression profiles with differentially expressed genes. The vessel-stabilizing factors were more highly expressed in HRMVPC, and the angiogenesis-promoting factors were more highly expressed in ASC. The vascular endothelial growth factor receptor-2 inhibition efficiently abolished the ASC angiogenic supportive capacities, whereas the addition of angiopoietin-1 and angiopoietin-2 did not alter these effects. Our results clearly show that ASC are pro-angiogenic, whereas HRMVPC are marked by anti-angiogenic/EC-stabilizing features. These data support ASC as pericyte replacement in DR but also suggest a careful risk-to-benefit analysis to take full advantage of the ASC therapeutic features.

Adipose mesenchymal stromal/stem cells expanded by a GMP compatible protocol displayed improved adhesion on cancer cells in flow conditions

Background

Adipose tissue derived mesenchymal stromal/stem cells (ASC) can be expanded using supernatant rich in growth factors (SRGF) as Good Manufacturing Practice compatible additive, instead of fetal bovine serum (FBS). After transendothelial migration, ASC can migrate to cancer masses where they can release active substances. Due to their homing and secretion properties ASC can be used as targeted drug delivery vehicles. Nevertheless, the fraction of ASC actually reaching the tumor target is limited. The impact of culture conditions on ASC homing potential on cancer cells is unknown.

Methods

In dynamic in vitro conditions, we perfused FBS or SRGF ASC in flow chambers coated with collagen type I and fibronectin or seeded with endothelial cells or with HT1080, T98G and Huh7 cancer cells. Expression of selected adhesion molecules was evaluated by standard cytofluorimetry. Dynamic intracellular calcium concentration changes were evaluated in microfluidic and static conditions.

Results

When compared to FBS ASC, not specific adhesion of SRGF ASC on collagen type I and fibronectin was lower (−33.9%±12.2% and −45.3%±16.9%), while on-target binding on HT1080 and T98G was enhanced (+147%±8% and 120.5%±5.2%). Adhesion of both FBS and SRGF ASC on Huh7 cells was negligible. As confirmed by citofluorimetry and by function-blocking antibody, SRGF mediated decrease of CD49a expression accounted for lower SRGF-ASC avidity for matrix proteins. Upon stimulation with calcium ionophore in static conditions, mobilization of intracellular calcium in SRGF ASC was greater than in FBS ASC. In dynamic conditions, upon adhesion on matrix proteins and HT1080 cells, SRGF ASC showed marked oscillatory calcium concentration changes.

Conclusions

SRGF can enhance specific ASC binding capacity on selected cancer cells as HT1080 (fibrosarcoma) and T98G (glioblastoma) cells. Upon cell-cell adhesion, SRGF ASC activate intracellular responses potentially improving cell secretion functions. SRGF ASC could be considered as suitable drug delivery vehicle for cancer therapy.

Production via good manufacturing practice of exofucosylated human mesenchymal stromal cells for clinical applications

BACKGROUND

The regenerative and immunomodulatory properties of human mesenchymal stromal cells (hMSCs) have raised great hope for their use in cell therapy. However, when intravenously infused, hMSCs fail to reach sites of tissue injury. Fucose addition in α(1,3)-linkage to terminal sialyllactosamines on CD44 creates the molecule known as hematopoietic cell E-/L-selectin ligand (HCELL), programming hMSC binding to E-selectin that is expressed on microvascular endothelial cells of bone marrow (BM), skin and at all sites of inflammation. Here we describe how this modification on BM-derived hMSCs (BM-hMSCs) can be adapted to good manufacturing practice (GMP) standards.

METHODS

BM-hMSCs were expanded using xenogenic-free media and exofucosylated using α(1,3)-fucosyltransferases VI (FTVI) or VII (FTVII). Enforced fucosylation converted CD44 into HCELL, and HCELL formation was assessed using Western blot, flow cytometry and cell-binding assays. Untreated (unfucosylated), buffer-treated and exofucosylated BM-hMSCs were each analyzed for cell viability, immunophenotype and differentiation potential, and E-selectin binding stability was assessed at room temperature, at 4°C, and after cryopreservation. Cell product safety was evaluated using microbiological testing, karyotype analysis, and c-Myc messenger RNA (mRNA) expression, and potential effects on genetic reprogramming and in cell signaling were analyzed using gene expression microarrays and receptor tyrosine kinase (RTK) phosphorylation arrays.

RESULTS

Our protocol efficiently generates HCELL on clinical-scale batches of BM-hMSCs. Exofucosylation yields stable HCELL expression for 48 h at 4°C, with retained expression after cell cryopreservation. Cell viability and identity are unaffected by exofucosylation, without changes in gene expression or RTK phosphorylation.

DISCUSSION

The described exofucosylation protocol using xenogenic-free reagents enforces HCELL expression on hMSCs endowing potent E-selectin binding without affecting cell viability or native phenotype. This described protocol is readily scalable for GMP-compliant clinical production.

Cryopreserved or Fresh Mesenchymal Stromal Cells: Only a Matter of Taste or Key to Unleash the Full Clinical Potential of MSC Therapy?

Mesenchymal stromal cells (MSCs) harbor great therapeutic potential for numerous diseases. From early clinical trials, success and failure analysis, bench-to-bedside and back-to-bench approaches, there has been a great gain in knowledge, still leaving a number of questions to be answered regarding optimal manufacturing and quality of MSCs for clinical application. For treatment of many acute indications, cryobanking may remain a prerequisite, but great uncertainty exists considering the therapeutic value of freshly thawed (thawed) and continuously cultured (fresh) MSCs. The field has seen an explosion of new literature lately, outlining the relevance of the topic. MSCs appear to have compromised immunomodulatory activity directly after thawing for clinical application. This may provide a possible explanation for failure of early clinical trials. It is not clear if and how quickly MSCs recover their full therapeutic activity, and if the "cryo stun effect" is relevant for clinical success. Here, we will share our latest insights into the relevance of these observations for clinical practice that will be discussed in the context of the published literature. We argue that the differences of fresh and thawed MSCs are limited but significant. A key issue in evaluating potency differences is the time point of analysis after thawing. To date, prospective double-blinded randomized clinical studies to evaluate potency of both products are lacking, although recent progress was made with preclinical assessment. We suggest refocusing therapeutic MSC development on potency and safety assays with close resemblance of the clinical reality.

Transcriptome profiling reveals differential expression of interferon family induced by dengue virus 2 in human endothelial cells on tissue culture plastic and polyacrylamide hydrogel

A cell model is critical for studying the molecular mechanisms of dengue virus 2 (DENV-2) invasions and cell bioactivity can be easily affected by the substrate matrix. Tissue culture plastic (TCP) and polyacrylamide hydrogel (PAMH) are two kinds of matrices widely used for cells. The effects of different matrices on the cultured cells with DENV-2 invasion remain unknown. To address the issue, the effects of TCP and PAMH were explored in primary human umbilical vein endothelial cells (HUVECs) with DENV-2 invasion. HUVECs were assigned into four groups: group A (cultured on TCP), group B (cultured on PAMH), group C (cultured on TCP with DENV-2 invasion), and group D (cultured on PAMH with DENV-2 invasion). Flow cytometry was performed on HUVECs after 48-hr culture. Gene expression patterns were analyzed by gene microarray. The levels of interleukin-29 (IL-29) were measured by real-time qRT-PCR and ELISA. There were no cell apoptosis induced by DENV-2 in HUVECs cultured on TCP and PAMH (P > 0.05). After DENV-2 invasion, the up-regulated genes involve in the activities of oligoadenylate synthetase (OAS), interferon-related cytokine, and growth factors so on. The up-regulated pathways involve in the responses to DENV-2 and innate immunity. IL-29 was induced in the HUVECs on PAMH when compared with the cells on TCP (P < 0.05). Thus, different matrices cause different immune responses, which should be considered in the cell models for exploring the molecular mechanisms of DENV-induced diseases.

Evaluation of GMP-compliant culture media for in vitro expansion of human bone marrow mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) from human bone marrow serve as a resource for cell-based therapies in regenerative medicine. Clinical applications require standardized protocols according to good manufacturing practice (GMP) guidelines. Donor variability as well as the intrinsic heterogeneity of MSC populations must be taken into consideration. The composition of the culture medium is a key factor in successful MSC expansion. The aim of this study was to comparatively assess the efficiency of xeno-free human platelet lysate (HPL)-based cell expansion with two commercially available media-StemPro MSC SFM CTS (for human ex vivo tissue and cell culture processing applications) and MSCGM (non-GMP-compliant, for research only)-in an academic setting as the first optimization step toward GMP-compliant manufacturing. We report the feasibility of MSC expansion up to the yielded cell number with all three media. MSCs exhibited the typical fibroblastoid morphology, with distinct differences in cell size depending on the medium. The differentiation capacity and characteristic immunophenotype were confirmed for all MSC populations. Proliferation was highest using StemPro MSC SFM CTS, whereas HPL medium was more cost-effective and its composition could be adjusted individually according to the respective needs. In summary, we present a comprehensive evaluation of GMP-compatible culture media for MSC expansion. Both StemPro and HPL medium proved to be suitable for clinical application and allowed sufficient cell proliferation. Specific differences were observed and should be considered according to the intended use. This study provides a detailed cost analysis and tools that may be helpful for the establishment of GMP-compliant MSC expansion.

Periostin enhances adipose-derived stem cell adhesion, migration, and therapeutic efficiency in Apo E deficient mice with hind limb ischemia

Introduction

Therapeutic angiogenesis by transplantation of autologous/allogeneic adipose-derived stem cells (ADSCs) is a potential approach for severe ischemic diseases. However, poor viability, adhesion, migration and differentiation limit the therapeutic efficiency after the cells were transplanted into the targeted area. Periostin, an extracellular matrix protein, exhibits a critical role in wound repair as well as promotes cell adhesion, survival, and angiogenesis.

Method

ADSCs were obtained and genetically engineered with periostin gene (P-ADSCs). The viability, proliferation, migration, and apoptosis of P-ADSCs under hypoxia were analyzed. Moreover, P-ADSCs were implanted into Apo E deficient mice with hind limb ischemia. The Laser Doppler perfusion index, immunofluorescence, and histological pathology assay were tested to evaluate the therapeutic effects. The associated molecular mechanism of periostin on the proliferation, adhesion, migration, and differentiation of ADSCs was also analyzed.

Results

The in vitro studies have shown that periostin-transfected ADSCs (P-ADSCs) promoted viability, proliferation, and migration of ADSCs. Apoptosis of ADSCs was inhibited under hypoxic conditions. The Laser Doppler perfusion index was significantly higher in the P-ADSCs group compared with that in the ADSC and control groups after 4 weeks. Immunofluorescence and histological pathology assay showed that the P-ADSCs were in and around the ischemic sites, and some cells differentiated into capillaries and endothelium. Microvessel densities were significantly improved in P-ADSCs group compared with those in the control group. The molecular mechanisms that provide the beneficial effects of periostin were connected with the upregulated expression of integrinβ1/FAK/PI3K/Akt/eNOS signal pathway and the increased secretion of growth factors.

Conclusion

Overexpression of periostin by gene transfection on ADSCs promotes survival, migration, and therapeutic efficiency, which will bring new insights into the treatment of critical limb ischemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0126-x) contains supplementary material, which is available to authorized users.

Expansion, harvest and cryopreservation of human mesenchymal stem cells in a serum-free microcarrier process

Human mesenchymal stem cell (hMSC) therapies are currently progressing through clinical development, driving the need for consistent, and cost effective manufacturing processes to meet the lot‐sizes required for commercial production. The use of animal‐derived serum is common in hMSC culture but has many drawbacks such as limited supply, lot‐to‐lot variability, increased regulatory burden, possibility of pathogen transmission, and reduced scope for process optimization. These constraints may impact the development of a consistent large‐scale process and therefore must be addressed. The aim of this work was therefore to run a pilot study in the systematic development of serum‐free hMSC manufacturing process. Human bone‐marrow derived hMSCs were expanded on fibronectin‐coated, non‐porous plastic microcarriers in 100 mL stirred spinner flasks at a density of 3 × 10⁵ cells.mL⁻¹ in serum‐free medium. The hMSCs were successfully harvested by our recently‐developed technique using animal‐free enzymatic cell detachment accompanied by agitation followed by filtration to separate the hMSCs from microcarriers, with a post‐harvest viability of 99.63 ± 0.03%. The hMSCs were found to be in accordance with the ISCT characterization criteria and maintained hMSC outgrowth and colony‐forming potential. The hMSCs were held in suspension post‐harvest to simulate a typical pooling time for a scaled expansion process and cryopreserved in a serum‐free vehicle solution using a controlled‐rate freezing process. Post‐thaw viability was 75.8 ± 1.4% with a similar 3 h attachment efficiency also observed, indicating successful hMSC recovery, and attachment. This approach therefore demonstrates that once an hMSC line and appropriate medium have been selected for production, multiple unit operations can be integrated to generate an animal component‐free hMSC production process from expansion through to cryopreservation. Biotechnol. Bioeng. 2015;112: 1696–1707. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Accelerated Development of Supramolecular Corneal Stromal-Like Assemblies from Corneal Fibroblasts in the Presence of Macromolecular Crowders

Tissue engineering by self-assembly uses the cells' secretome as a regeneration template and biological factory of trophic factors. Despite the several advantages that have been witnessed in preclinical and clinical settings, the major obstacle for wide acceptance of this technology remains the tardy extracellular matrix formation. In this study, we assessed the influence of macromolecular crowding (MMC)/excluding volume effect, a biophysical phenomenon that accelerates thermodynamic activities and biological processes by several orders of magnitude, in human corneal fibroblast (HCF) culture. Our data indicate that the addition of negatively charged galactose derivative (carrageenan) in HCF culture, even at 0.5% serum, increases by 12-fold tissue-specific matrix deposition, while maintaining physiological cell morphology and protein/gene expression. Gene analysis indicates that a glucose derivative (dextran sulfate) may drive corneal fibroblasts toward a myofibroblast lineage. Collectively, these results indicate that MMC may be suitable not only for clinical translation and commercialization of tissue engineering by self-assembly therapies, but also for the development of in vitro pathophysiology models.

Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies

Therapeutic strategies based on the principles of tissue engineering by self-assembly put forward the notion that functional regeneration can be achieved by utilising the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, in dilute ex vivo microenvironments, prolonged culture time is required to develop an extracellular matrix-rich implantable device. Herein, we assessed the influence of macromolecular crowding, a biophysical phenomenon that regulates intra- and extra-cellular activities in multicellular organisms, in human corneal fibroblast culture. In the presence of macromolecules, abundant extracellular matrix deposition was evidenced as fast as 48 h in culture, even at low serum concentration. Temperature responsive copolymers allowed the detachment of dense and cohesive supramolecularly assembled living substitutes within 6 days in culture. Morphological, histological, gene and protein analysis assays demonstrated maintenance of tissue-specific function. Macromolecular crowding opens new avenues for a more rational design in engineering of clinically relevant tissue modules in vitro.

Human peripheral blood CD34+ cells attenuate oleic acid-induced acute lung injury in rats

BACKGROUND AIMS

Adult stem cell-based therapy is a promising novel approach for treatment of acute lung injury (ALI). In this study, we evaluated the therapeutic effect of isolated human peripheral blood CD34+ progenitor cells in an ALI rat model, induced by oleic acid (OA) injection.

METHODS

Seventy-five adult female rats were used in this study. Group A, control without treatment, and group B, control injected with phosphate-buffered saline, comprised 15 rats each; the remaining 45 rats were injected with OA to induce ALI and were further subdivided into 3 groups: group C (ALI group, 15 rats), group D (ALI and fibroblast group, 15 rats) and group E (ALI and CD34+ cell group, 15 rats).

RESULTS

CD34+ cells transplantation in rats with OA-induced lung injury improves the arterial PaO(2) and wet/dry ratio, reduces infiltration of inflammatory cells and decreases lung vascular permeability as determined by reduced intra-alveolar and interstitial patchy congestion and hemorrhage as well as decreased interstitial edema. Additionally, lung inflammation determined by expression of the pro-inflammatory mediators intercellular adhesion molecule 1 and tumor necrosis factor-α was attenuated in CD34+ cell-treated rats at 6, 24 and 48 h post-OA challenge compared with non-treated rats. Moreover, the expression of anti-inflammatory molecule interleukin-10 was up-regulated in the lung of OA-induced ALI rats after administration of CD34+ cells. The important finding was that human TNF-α-induced protein 6 (TSG-6) gene expression was significantly up-regulated in rats treated with CD34+ cells.

CONCLUSIONS

The freshly isolated human peripheral blood-derived CD34+ cells may be used as an important source of stem cells that improve ALI. The anti-inflammatory properties of CD34+ cells in the lung are explained, at least in part, by activation of CD34+ cells to express TSG-6.

Standardization of Good Manufacturing Practice-compliant production of bone marrow-derived human mesenchymal stromal cells for immunotherapeutic applications

BACKGROUND AIMS

Human mesenchymal stem or stromal cells (MSCs) represent a potential resource not only for regenerative medicine but also for immunomodulatory cell therapies. The application of different MSC culture protocols has significantly hampered the comparability of experimental and clinical data from different laboratories and has posed a major obstacle for multicenter clinical trials. Manufacturing of cell products for clinical application in the European Community must be conducted in compliance with Good Manufacturing Practice and requires a manufacturing license. In Germany, the Paul-Ehrlich-Institut as the Federal Authority for Vaccines and Biomedicines is critically involved in the approval process.

METHODS

This report summarizes a consensus meeting between researchers, clinicians and regulatory experts on standard quality requirements for MSC production.

RESULTS

The strategy for quality control testing depends on the product's cell composition, the manufacturing process and the indication and target patient population. Important quality criteria in this sense are, among others, the immunophenotype of the cells, composition of the culture medium and the risk for malignant transformation, as well as aging and the immunosuppressive potential of the manufactured MSCs.

CONCLUSIONS

This position paper intends to provide relevant information to interested parties regarding these criteria to foster the development of scientifically valid and harmonized quality standards and to support approval of MSC-based investigational medicinal products.

Human CD34+ progenitor cells freshly isolated from umbilical cord blood attenuate inflammatory lung injury following LPS challenge

Adult stem cell-based therapy is a promising novel approach for treatment of acute lung injury. Here we investigated the therapeutic potential of freshly isolated human umbilical cord blood CD34⁺ progenitor cells (fCB-CD34⁺ cells) in a mouse model of acute lung injury. At 3 h post-lipopolysaccharide (LPS) challenge, fCB-CD34⁺ cells were transplanted i.v. to mice while CD34⁻ cells or PBS were administered as controls in separate cohorts of mice. We observed that fCB-CD34⁺ cell treatment inhibited lung vascular injury evident by decreased lung vascular permeability. In contrast, CD34⁻ cells had no effects on lung vascular injury. Lung inflammation determined by myeloperoxidase activity, neutrophil sequestration and expression of pro-inflammatory mediators was attenuated in fCB-CD34⁺ cell-treated mice at 26 h post-LPS challenge compared to PBS or CD34⁻ cell-treated controls. Importantly, lung inflammation in fCB-CD34⁺ cell-treated mice was returned to normal levels as seen in basal mice at 52 h post-LPS challenge whereas PBS or CD34⁻ cell-treated control mice exhibited persistent lung inflammation. Accordingly, fCB-CD34⁺ cell-treated mice exhibited a marked increase of survival rate. Employing in vivo 5-bromo-2′-deoxyuridine incorporation assay, we found a drastic induction of lung endothelial proliferation in fCB-CD34⁺ cell-treated mice at 52 h post-LPS compared to PBS or CD34⁻ cell-treated controls, which contributed to restoration of vascular integrity and thereby inhibition of lung inflammation. Taken together, these data have demonstrated the protective effects of fCB-CD34⁺ cell on acute lung injury induced by LPS challenge, suggesting fCB-CD34⁺ cells are an important source of stem cells for the treatment of acute lung injury.

Platelet lysate as replacement for fetal bovine serum in mesenchymal stromal cell cultures

Mesenchymal stromal cells (MSC) emerged as highly attractive in cell-based regenerative medicine. Initially thought to provide cells capable of differentiation towards mesenchymal cell types (osteoblasts, chondrocytes, adipocytes etc.), by and by potent immunoregulatory and pro-regenerative activities have been discovered, broadening the field of potential applications from bone and cartilage regeneration to wound healing and treatment of autoimmune diseases. Due to the limited frequency in most tissue sources, ex vivo expansion of MSC is required compliant with good manufacturing practice (GMP) guidelines to yield clinically relevant cell doses. Though, still most manufacturing protocols use fetal bovine serum (FBS) as cell culture supplement to isolate and to expand MSC. However, the high lot-to-lot variability as well as risk of contamination and immunization call for xenogenic-free culture conditions. In terms of standardization, chemically defined media appear as the ultimate achievement. Since these media need to maintain all key cellular and therapy-relevant features of MSC, the development of chemically defined media is still - albeit highly investigated - only in its beginning. The current alternatives to FBS rely on human blood-derived components: plasma, serum, umbilical cord blood serum, and platelet derivatives like platelet lysate. Focusing on quality aspects, the latter will be addressed within this review.

Transplantation of modified human adipose derived stromal cells expressing VEGF165 results in more efficient angiogenic response in ischemic skeletal muscle

Background

Modified cell-based angiogenic therapy has become a promising novel strategy for ischemic heart and limb diseases. Most studies focused on myoblast, endothelial cell progenitors or bone marrow mesenchymal stromal cells transplantation. Yet adipose-derived stromal cells (in contrast to bone marrow) are abundantly available and can be easily harvested during surgery or liposuction. Due to high paracrine activity and availability ADSCs appear to be a preferable cell type for cardiovascular therapy. Still neither genetic modification of human ADSC nor in vivo therapeutic potential of modified ADSC have been thoroughly studied. Presented work is sought to evaluate angiogenic efficacy of modified ADSCs transplantation to ischemic tissue.

Materials and methods

Human ADSCs were transduced using recombinant adeno-associated virus (rAAV) serotype 2 encoding human VEGF165. The influence of genetic modification on functional properties of ADSCs and their angiogenic potential in animal models were studied.

Results

We obtained AAV-modified ADSC with substantially increased secretion of VEGF (VEGF-ADSCs). Transduced ADSCs retained their adipogenic and osteogenic differentiation capacities and adhesion properties. The level of angiopoetin-1 mRNA was significantly increased in VEGF-ADSC compared to unmodified cells yet expression of FGF-2, HGF and urokinase did not change. Using matrigel implant model in mice it was shown that VEGF-ADSC substantially stimulated implant vascularization with paralleling increase of capillaries and arterioles. In murine hind limb ischemia test we found significant reperfusion and revascularization after intramuscular transplantation of VEGF-ADSC compared to controls with no evidence of angioma formation.

Conclusions

Transplantation of AAV-VEGF- gene modified hADSC resulted in stronger therapeutic effects in the ischemic skeletal muscle and may be a promising clinical treatment for therapeutic angiogenesis.