Comparison of different culture conditions for human mesenchymal stromal cells for clinical stem cell therapy

Comprehensive assessment of goat adipose tissue-derived mesenchymal stem cells cultured in different media

Mesenchymal stem cells (MSCs) have demonstrated potential in treating livestock diseases that are unresponsive to conventional therapies. MSCs derived from goats, a valuable model for studying orthopaedic disorders in humans, offer insights into bone formation and regeneration. Adipose tissue-derived MSCs (ADSCs) are easily accessible and have a high capacity for expansion. Although the choice of culture media significantly influences the biological properties of MSCs, the optimal media for goat ADSCs (gADSCs) remains unclear. This study aimed to assess the effects of four commonly used culture media on gADSCs' culture characteristics, stem cell-specific immunophenotype, and differentiation. Results showed that MEM, DMEM/F12, and DMEM-LG were superior in maintaining cell morphology and culture parameters of gADSCs, such as cell adherence, metabolic activity, colony-forming potential, and population doubling. Conversely, DMEM-HG exhibited poor performance across all evaluated parameters. The gADSCs cultured in DMEM/F12 showed enhanced early proliferation and lower apoptosis. The cell surface marker distribution exhibited superior characteristics in gADSCs cultured in MEM and DMEM/F12. In contrast, the distribution was inferior in gADSCs cultured in DMEM-LG. DMEM/F12 and DMEM-LG culture media demonstrated a significantly higher potential for chondrogenic differentiation and DMEM-LG for osteogenic differentiation. In conclusion, DMEM/F12 is a suitable culture medium for propagating gADSCs as it effectively maintains cell morphology, growth parameters, proliferation and lower apoptosis while exhibiting desirable expression patterns of MSC-specific markers. These findings contribute to optimising culture conditions for gADSCs, enhancing their potential applications in disease treatment and regenerative medicine.

Inorganic Nanoparticles-Based Systems in Biomedical Applications of Stem Cells: Opportunities and Challenges

Stem cells (SC) are a kind of cells with self renewing ability and multipotent differentiation, which can differentiate into many types of cells such as osteoblast, chondrocyte, neurocyte to treat disease like osteoporosis, osteoarthritis and Alzheimer's disease. Despite the development of novel methods for inducing cell differentiation, the inefficiency and complexity of controlling differentiation of stem cells remain a serious challenge, which necessary to develop a new and alternative approach for effectively controlling the direction of stem cell differentiation in vitro and in vivo in stem cells therapy. Recent advancement in nanotechnology for developing a new class of inorganic nanoparticles that exhibit unique chemical and physical properties holds promise for the treatment of stem cells. Over the last decade, inorganic nanoparticle-based approaches against stem cells have been directed toward developing nanoparticles with drug delivery, or utilizing nanoparticles for controlled cell behaviors, and applying nanoparticles for inducing cell differentiation directly. In addition, a strategy to functionalize inorganic nanoparticles as a nanoprobe towards enhanced penetration through near-infrared light or nuclear magnetic resonance has been receiving considerable interest by means of long-term tracking stem cell in vivo. This review summarizes and highlights the recent development of these inorganic nanoparticle-based approaches as potential therapeutics for controlling differentiation of stem cells and so on for stem cell therapy, along with current opportunities and challenges that need to be overcome for their successful clinical translation.

Functional properties of equine adipose-derived mesenchymal stromal cells cultured with equine platelet lysate

Successful translation of multipotent mesenchymal stromal cell (MSC)-based therapies into clinical reality relies on adequate cell production procedures. These should be available not only for human MSC, but also for MSC from animal species relevant to preclinical research and veterinary medicine. The cell culture medium supplementation is one of the critical aspects in MSC production. Therefore, we previously established a scalable protocol for the production of buffy-coat based equine platelet lysate (ePL). This ePL proved to be a suitable alternative to fetal bovine serum (FBS) for equine adipose-derived (AD-) MSC culture so far, as it supported AD-MSC proliferation and basic characteristics. The aim of the current study was to further analyze the functional properties of equine AD-MSC cultured with the same ePL, focusing on cell fitness, genetic stability and pro-angiogenic potency. All experiments were performed with AD-MSC from n = 5 horses, which were cultured either in medium supplemented with 10% FBS, 10% ePL or 2.5% ePL. AD-MSC cultured with 2.5% ePL, which previously showed decreased proliferation potential, displayed higher apoptosis but lower senescence levels as compared to 10% ePL medium (p < 0.05). Non-clonal chromosomal aberrations occurred in 8% of equine AD-MSC cultivated with FBS and only in 4.8% of equine AD-MSC cultivated with 10% ePL. Clonal aberrations in the AD-MSC were neither observed in FBS nor in 10% ePL medium. Analysis of AD-MSC and endothelial cells in an indirect co-culture revealed that the ePL supported the pro-angiogenic effects of AD-MSC. In the 10% ePL group, more vascular endothelial growth factor (VEGF-A) was released and highest VEGF-A concentrations were reached in the presence of ePL and co-cultured cells (p < 0.05). Correspondingly, AD-MSC expressed the VEGF receptor-2 at higher levels in the presence of ePL (p < 0.05). Finally, AD-MSC and 10% ePL together promoted the growth of endothelial cells and induced the formation of vessel-like structures in two of the samples. These data further substantiate that buffy-coat-based ePL is a valuable supplement for equine AD-MSC culture media. The ePL does not only support stable equine AD-MSC characteristics as demonstrated before, but it also enhances their functional properties.

Current therapeutic strategies for respiratory diseases using mesenchymal stem cells

Mesenchymal stromal/stem cells (MSCs) have a great potential to proliferate, undergo multi-directional differentiation, and exert immunoregulatory effects. There is already much enthusiasm for their therapeutic potentials for respiratory inflammatory diseases. Although the mechanism of MSCs-based therapy has been well explored, only a few articles have summarized the key advances in this field. We hereby provide a review over the latest progresses made on the MSCs-based therapies for four types of inflammatory respiratory diseases, including idiopathic pulmonary fibrosis, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, and the uncovery of their underlying mechanisms from the perspective of biological characteristics and functions. Furthermore, we have also discussed the advantages and disadvantages of the MSCs-based therapies and prospects for their optimization.

Surfing the clinical trials of mesenchymal stem cell therapy in ischemic cardiomyopathy

While existing remedies failed to fully address the consequences of heart failure, stem cell therapy has been introduced as a promising approach. The present review is a comprehensive appraisal of the impacts of using mesenchymal stem cells (MSCs) in clinical trials mainly conducted on ischemic cardiomyopathy. The benefits of MSC therapy for dysfunctional myocardium are likely attributed to numerous secreted paracrine factors and immunomodulatory effects. The positive outcomes associated with MSC therapy are scar size reduction, reverse remodeling, and angiogenesis. Also, a decreasing in the level of chronic inflammatory markers of heart failure progression like TNF-α is observed. The intense inflammatory reaction in the injured myocardial micro-environment predicts a poor response of scar tissue to MSC therapy. Subsequently, the interval delay between myocardial injury and MSC therapy is not yet determined. The optimal requested dose of cells ranges between 100 to 150 million cells. Allogenic MSCs have different advantages compared to autogenic cells and intra-myocardial injection is the preferred delivery route. The safety and efficacy of MSCs-based therapy have been confirmed in numerous studies, however several undefined parameters like route of administration, optimal timing, source of stem cells, and necessary dose are limiting the routine use of MSCs therapeutic approach in clinical practice. Lastly, pre-conditioning of MSCs and using of exosomes mediated MSCs or genetically modified MSCs may improve the overall therapeutic effect. Future prospective studies establishing a constant procedure for MSCs transplantation are required in order to apply MSC therapy in our daily clinical practice and subsequently improving the overall prognosis of ischemic heart failure patients.

Towards Physiologic Culture Approaches to Improve Standard Cultivation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are of great interest for their use in cell-based therapies due to their multipotent differentiation and immunomodulatory capacities. In consequence of limited numbers following their isolation from the donor tissue, MSCs require extensive expansion performed in traditional 2D cell culture setups to reach adequate amounts for therapeutic use. However, prolonged culture of MSCs in vitro has been shown to decrease their differentiation potential and alter their immunomodulatory properties. For that reason, preservation of these physiological characteristics of MSCs throughout their in vitro culture is essential for improving the efficiency of therapeutic and in vitro modeling applications. With this objective in mind, many studies already investigated certain parameters for enhancing current standard MSC culture protocols with regard to the effects of specific culture media components or culture conditions. Although there is a lot of diversity in the final therapeutic uses of the cells, the primary stage of standard isolation and expansion is imperative. Therefore, we want to review on approaches for optimizing standard MSC culture protocols during this essential primary step of in vitro expansion. The reviewed studies investigate and suggest improvements focused on culture media components (amino acids, ascorbic acid, glucose level, growth factors, lipids, platelet lysate, trace elements, serum, and xenogeneic components) as well as culture conditions and processes (hypoxia, cell seeding, and dissociation during passaging), in order to preserve the MSC phenotype and functionality during the primary phase of in vitro culture.

Human Adipose Tissue-Derived Stromal Cells Suppress Human, but Not Murine Lymphocyte Proliferation, via Indoleamine 2,3-Dioxygenase Activity

Over recent years, mesenchymal stromal cells (MSC) have gained immense attraction in immunotherapy, regenerative medicine and tissue engineering. MSC microenvironment modulation occurs through synergy of direct cell-cell contact, and secreted soluble factors and extracellular vesicles (EV). MSC-derived EV have been suggested as cell-free immunomodulatory alternative to MSC; however, previous findings have challenged this. Furthermore, recent data suggest that evaluating the mechanism of action of human MSC (hMSC) in animal models might promote adverse immune reactions or lack of functionality due to xeno-incompatibilities. In this study, we first assessed the immunomodulatory strength of different human MSC sources on in vitro stimulated T cells and compared this to interferon-gamma (IFNγ) primed MSC conditioned medium (CM) and EV. Second, we addressed the main molecular mechanisms, and third, we assessed the MSC in vitro immunosuppressive effect across interspecies barriers. We identified human adipose tissue-derived stromal cells (ASC) with strongest immunomodulatory strength, followed by bone marrow (BM) and cord blood-derived MSC (CB). Whilst CM from primed ASC managed to exert analogous effects as their cellular counterpart, EV derived thereof did not, reproducing previous findings. IFNγ-induced indoleamine 2,3-dioxygenase (IDO) activity was identified as key mechanism to suppress human lymphocyte proliferation, as in the presence of the IDO inhibitor epacadostat (Epac) a stimulation of proliferation was seen. In addition, we revealed MSC immunosuppressive effects to be species-specific, because human cells failed to suppress murine lymphocyte proliferation. In summary, ASC were the strongest immunomodulators with the IDO-kynurenine pathway being key within the human system. Importantly, the in vitro lack of interspecies immunomodulatory strength suggests that preclinical data need to be carefully interpreted especially when considering a possible translation to clinical field.

Growth and proliferation of caprine bone marrow mesenchymal stem cells on different culture media

The growth and proliferation of mesenchymal stem cells are very sensitive in in vitro and a number of factors like media play a significant role in that context. In this study we assessed effect of different media on growth and proliferation of bone marrow derived mesenchymal stem cells (BMMSCs). The BMMSCs were isolated from caprine bone marrow and were subjected to magnetic activated cell sorting against CD90⁺, CD105⁺, CD271⁺and CD34^- along with FC blocker. After characterisation, 2 × 10⁴ cells were seeded in 12 well culture plates in four different media viz. MesenCult, MesenPRO, StemPro and complete DMEM (15 % FBS) to study their growth kinetic for 6 days from passage 0 (P0) to passage 3 (P3). The population doubling time (PDT) was derived from growth curve using logarithmic formula. The results showed that the BMMSCs growth and proliferation was highest in MesenCult media in P0 which varied significantly (p < 0.05) from rest of media and from P1 to P3, it was MesenPRO which yielded maximum cells (p < 0.05). The PDT was also in line with growth curve findings. In conclusion, the MesenPRO media had higher growth and proliferation rate from P1 to P3 although MesenCult had higher cell numbers in P0. In conclusion, the use of MesenPRO media could be a better option than conventional media when mesenchymal stem cells are used in clinical applications and other therapeutic purposes taking consideration to its higher growth and proliferation rate. And MesenCult would be a great option to harvest MSCs from P0.

Differences between the Proliferative Effects of Human Platelet Lysate and Fetal Bovine Serum on Human Adipose-Derived Stem Cells

Background: Recently, human adipose-derived stem cells (hASCs) were discovered in the human subcutaneous adipose tissue. PLTMax Human Platelet Lysate (PLTMax), a supplement refined from human platelets, has been reported to have proliferative effects on bone marrow mesenchymal stem cells. The proliferative effects of PLTMax on ASCs were investigated in this study. Methods: The ASCs in DMEM (serum-free), DMEM+PLTMax (1%, 2%, 5%, and 10%), and DMEM+FBS (10%) were cultivated for two, five, and seven days. The cell growth rate was examined, BrdU incorporation, and the cell cycle and Ki-67 immunostaining were performed. The cell growth rate was investigated when each inhibitor (PD98059, SP600125, SB203580, and LY294002) was added and phosphorylation of ERK1/2, JNK, p38, and Akt were examined by western blotting. The cell surface marker of hASCs was also analyzed. Results: The cells in the PLTMax (5%) group showed significantly more proliferation compared to the cells in control (serum-free) and FBS (10%) groups, and a significant increase in the number of cells in the S phase and G2/M phase. The number of Ki-67 positive cells increased significantly in the DMEM+ PLTMax (5%) and the FBS (10%) groups. The addition of inhibitors PD98059, SP600125, SB203580, and LY294002 decreased the proliferative effects of PLTMax on ASCs. Phosphorylation of ERK1/2, JNK, p38, and Akt was observed in both the PLTMax (5%) and the FBS (10%) groups. Conclusions: For human adipose stem cells, 5% PLTMax was the optimum concentration, which showed a significantly higher proliferative effect than 10% FBS. PLTMax is a useful medium additive, which can substitute FBS. The proliferative effects of PLTMax are suggested to function via multiple signaling pathways, similar to FBS.

Bench-to-bedside optimization of mesenchymal stem cell isolation, processing, and expansion for in vivo administration

Aim: In this study, we aimed at identifying the optimal conditions for isolation, processing and expansion of mesenchymal stem cells (MSCs). Methods: Porcine bone marrow was obtained from either small- or large-volume bone marrow aspirate (BMA). Next, three BMA processing methods were compared. Finally, the best condition was selected from various culture parameters, including basal media, supplementation and seeding density. Results: Our results demonstrate that a small-volume BMA and direct plating yields significantly higher concentration of MSCs. Basal media supplementation with 10% platelet lysate and seeding density of 1000 cells/cm² can generate large numbers of multipotent MSCs with augmented function and low population doublings. Conclusion: This work provides guidance for preparation of robust MSCs for future clinical trials.

Extracellular vesicles generated by placental tissues ex vivo: A transport system for immune mediators and growth factors

PROBLEM

To study the mechanisms of placenta function and the role of extracellular vesicles (EVs) in pregnancy, it is necessary to develop an ex vivo system that retains placental cytoarchitecture and the primary metabolic aspects, in particular the release of EVs and soluble factors. Here, we developed such a system and investigated the pattern of secretion of cytokines, growth factors, and extracellular vesicles by placental villous and amnion tissues ex vivo.

METHODS OF STUDY

Placental villous and amnion explants were cultured for 2 weeks at the air/liquid interface and their morphology and the released cytokines and EVs were analyzed. Cytokines were analyzed with multiplexed bead assays, and individual EVs were analyzed with recently developed techniques that involved EV capture with magnetic nanoparticles coupled to anti-EV antibodies and flow cytometry.

RESULTS

Ex vivo tissues (i) remained viable and preserved their cytoarchitecture; (ii) maintained secretion of cytokines and growth factors; (iii) released EVs of syncytiotrophoblast and amnion epithelial cell origins that contain cytokines and growth factors.

CONCLUSION

A system of ex vivo placental villous and amnion tissues can be used as an adequate model to study placenta metabolic activity in normal and complicated pregnancies, in particular to characterize EVs by their surface markers and by encapsulated proteins. Establishment and benchmarking the placenta ex vivo system may provide new insight in the functional status of this organ in various placental disorders, particularly regarding the release of EVs and cytokines. Such EVs may have a prognostic value for pregnancy complications.

Low-affinity Nerve Growth Factor Receptor (CD271) Heterogeneous Expression in Adult and Fetal Mesenchymal Stromal Cells

Human multipotent mesenchymal stromal cells (MSC) are isolated from a plethora of tissue sources for cell therapy purposes. In 2006, the International Society for Cellular Therapy (ISCT) published minimal guidelines to define MSC identity. Nevertheless, many independent studies demonstrated that cells meeting the ISCT criteria possessed heterogeneous phenotypes and functionalities, heavily influenced by culture conditions. In this study, human MSC derived from many adult (bone marrow and adipose tissue) or fetal (cord blood, Wharton's jelly, umbilical cord perivascular compartment and amniotic fluid) tissues were investigated. Their immunophenotype was analyzed to define consistent source-specific markers by extensive flow cytometry analysis and real-time qRT-PCR. CD271⁺ subpopulations were detected in adult MSC, whereas NG2 was significantly more expressed in fetal MSC but failed validation on independent samples coming from an external laboratory. The highest number of CD271⁺ adult MSC were detected soon after isolation in serum-based culture conditions. Furthermore, heterogeneous percentages of CD271 expression were found in platelet lysate-based or serum-free culture conditions. Finally, CD271⁺ adult MSC showed high clonogenic and osteogenic properties as compared to CD271^- cells. To conclude, in this phenotype-function correlation study CD271⁺ subpopulation confers heterogeneity on adult MSC, confirming the need of more specific markers to address MSC properties.

Limbal niche cells are a potent resource of adult mesenchymal progenitors

Limbal niche cells located in the limbal Palisades of Vogt are mesenchymal stem cells that reside next to limbal basal epithelial cells. Limbal niche cells are progenitors that express embryonic stem cell markers such as Nanog, Nestin, Oct4, Rex1, Sox2 and SSEA4, mesenchymal cell markers such as CD73, CD90 and CD105, and angiogenesis markers such as Flk-1, CD31, CD34, VWF, PDGFRβ and α-SMA, but negative for CD45. In addition, the stemness of limbal niche cells can be maintained during their cell culture in a three-dimension environment. Furthermore, expanded limbal niche cells have the capability to undergo adipogenesis, chondrogenesis, osteogenesis and endogenesis in vitro, indicating that they are in fact a valuable resource of adult progenitors. Furthermore studies on how the limbal niche cells regulate the aforementioned stemness and corneal fate decision are warranted, as those investigations will shed new light on how mesenchymal progenitors reverse limbal stem cell deficiency and lead to new methods for limbal niche cell treatment.

Platelet lysate as a novel serum-free media supplement for the culture of equine bone marrow-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) produced for clinical purposes rely on culture media containing fetal bovine serum (FBS) which is xenogeneic and has the potential to significantly alter the MSC phenotype, rendering these cells immunogenic. As a result of bovine-derived exogenous proteins expressed on the cell surface, MSCs may be recognized by the host immune system as non-self and be rejected. Platelet lysate (PL) may obviate some of these concerns and shows promising results in human medicine as a possible alternative to FBS. Our goal was to evaluate the use of equine platelet lysate (ePL) pooled from donor horses in place of FBS to culture equine MSCs. We hypothesized that ePL, produced following apheresis, will function as the sole media supplement to accelerate the expansion of equine bone marrow-derived MSCs without altering their phenotype and their immunomodulatory capacity.

Methods

Platelet concentrate was obtained via plateletpheresis and ePL were produced via freeze-thaw and centrifugation cycles. Population doublings (PD) and doubling time (DT) of bone marrow-derived MSCs (n = 3) cultured with FBS or ePL media were calculated. Cell viability, immunophenotypic analysis, and trilineage differentiation capacity of MSCs were assessed accordingly. To assess the ability of MSCs to modulate inflammatory responses, E. coli lipopolysaccharide (LPS)-stimulated monocytes were cocultured with MSCs cultured in the two different media formulations, and cell culture supernatants were assayed for the production of tumor necrosis factor (TNF)-α.

Results

Our results showed that MSCs cultured in ePL media exhibited similar proliferation rates (PD and DT) compared with those cultured in FBS at individual time points. MSCs cultured in ePL showed a statistically significant increased viability following a single washing step, expressed similar levels of MSC markers compared to FBS, and were able to differentiate towards the three lineages. Finally, MSCs cultured in ePL efficiently suppressed the release of TNF-α when exposed to LPS-stimulated monocytes similar to those cultured in FBS.

Conclusion

ePL has the potential to be used for the expansion of MSCs before clinical application, avoiding the concerns associated with the use of FBS.

Cryopreservation and Revival of Human Mesenchymal Stromal Cells

Cell-based therapy is a promising and innovative new treatment for different degenerative and autoimmune diseases, and mesenchymal stromal cells (MSCs) from the bone marrow have demonstrated great therapeutic potential due to their immunosuppressive and regenerative capacities.The establishment of methods for large-scale expansion of clinical-grade MSCs in vitro has paved the way for their therapeutic use in clinical trials. However, the clinical application of MSCs also requires cryopreservation and banking of the cell products. To preserve autologous or allogeneic MSCs for future clinical applications, a reliable and effective cryopreservation method is required.Developing a successful cryopreservation protocol for clinical stem cell products, cryopreservation media, cryoprotectant agents (CPAs), the freezing container, the freezing temperature, and the cooling and warming rate are all aspects which should be considered.A major challenge is the selection of a suitable cryoprotectant which is able to penetrate the cells and yet has low toxicity.This chapter focuses on recent technological developments relevant for the cryopreservation of MSCs using the most commonly used cryopreservation medium containing DMSO and animal serum or human-derived products for research use and the animal protein-free cryopreservation media CryoStor (BioLife Solutions) for clinical use.

Adipose-derived stem cell differentiation as a basic tool for vascularized adipose tissue engineering

The development of in vitro adipose tissue constructs is highly desired to cope with the increased demand for substitutes to replace damaged soft tissue after high graded burns, deformities or tumor removal. To achieve clinically relevant dimensions, vascularization of soft tissue constructs becomes inevitable but still poses a challenge. Adipose-derived stem cells (ASCs) represent a promising cell source for the setup of vascularized fatty tissue constructs as they can be differentiated into adipocytes and endothelial cells in vitro and are thereby available in sufficiently high cell numbers. This review summarizes the currently known characteristics of ASCs and achievements in adipogenic and endothelial differentiation in vitro. Further, the interdependency of adipogenesis and angiogenesis based on the crosstalk of endothelial cells, stem cells and adipocytes is addressed at the molecular level. Finally, achievements and limitations of current co-culture conditions for the construction of vascularized adipose tissue are evaluated.

Comparison of clinical grade human platelet lysates for cultivation of mesenchymal stromal cells from bone marrow and adipose tissue

BACKGROUND

The utility of mesenchymal stromal cells (MSCs) in therapeutic applications for regenerative medicine has gained much attention. Clinical translation of MSC-based approaches requires in vitro culture-expansion to achieve a sufficient number of cells. The ideal cell culture medium should be devoid of any animal derived components. We have evaluated whether human Platelet Lysate (hPL) could be an attractive alternative to animal supplements.

METHODS

MSCs from bone marrow (BMSCs) and adipose tissue-derived stromal cells (ASCs) obtained from three donors were culture expanded in three different commercially available hPL fulfilling good manufacturing practice criteria for clinical use. BMSCs and ASCs cultured in Minimum Essential Medium Eagle-alpha supplemented with 5% PLT-Max (Mill Creek), Stemulate™ PL-S and Stemulate™ PL-SP (COOK General Biotechnology) were compared to standard culture conditions with 10% fetal bovine serum (FBS). Cell morphology, proliferation, phenotype, genomic stability, and differentiation potential were analyzed.

RESULTS

Regardless of manufacturer, BMSCs and ASCs cultured in hPL media showed a significant increase in proliferation capacity compared to FBS medium. In general, the immunophenotype of both BMSCs and ASCs fulfilled International Society for Cellular Therapy (ISCT) criteria after hPL media expansion. Comparative genomic hybridization measurements demonstrated no unbalanced chromosomal rearrangements for BMSCs or ASCs cultured in hPL media or FBS medium. The BMSCs and ASCs could differentiate into osteogenic, adipogenic, or chondrogenic lineages in all four culture conditions.

CONCLUSION

All three clinically approved commercial human platelet lysates accelerated proliferation of BMSCs and ASCs and the cells meet the ISCT mesenchymal phenotypic requirements without exhibiting chromosomal aberrations.

Influence of vascular endothelial growth factor stimulation and serum deprivation on gene activation patterns of human adipose tissue-derived stromal cells

Introduction

Stimulation of mesenchymal stromal cells and adipose tissue-derived stromal cells (ASCs) with vascular endothelial growth factor (VEGF) has been used in multiple animal studies and clinical trials for regenerative purposes. VEGF stimulation is believed to promote angiogenesis and VEGF stimulation is usually performed under serum deprivation. Potential regenerative molecular mechanisms are numerous and the role of contributing factors is uncertain. The aim of the current study was to investigate the effect of in vitro serum deprivation and VEGF stimulation on gene expression patterns of ASCs.

Methods

Gene expressions of ASCs cultured in complete medium, ASCs cultured in serum-deprived medium and ASCs stimulated with VEGF in serum-deprived medium were compared. ASC characteristics according to criteria set by the International Society of Cellular Therapy were confirmed by flow cytometry. Microarray gene expressions were obtained using the Affymetrix HT HG-U133+ GeneChip®. Gene set enrichment analysis was performed using the Kyoto Encyclopedia of Genes and Genomes and gene ontology terms. Transcription of selected genes of interest was confirmed by quantitative PCR.

Results

Compared to ASCs in complete medium, 190 and 108 genes were significantly altered by serum deprivation and serum deprivation combined with VEGF, respectively. No significant differences in gene expression patterns between serum-deprived ASCs and serum-deprived ASCs combined with VEGF stimulation were found. Genes most prominently and significantly upregulated by both conditions were growth factors (IGF1, BMP6, PDGFD, FGF9), adhesion molecule CLSTN2, extracellular matrix-related proteins such as matricellular proteins SMOC2, SPON1 and ADAMTS12, and inhibitors of proliferation (JAG1). The most significantly downregulated genes included matrix metalloproteinases (MMP3, MMP1), and proliferation markers (CDKN3) and GREM2 (a BMP6 antagonist).

Conclusion

The decisive factor for the observed change in ASC gene expression proves to be serum starvation rather than VEGF stimulation. Changes in expression of growth factors, matricellular proteins and matrix metalloproteinases in concert, diverge from direct pro-angiogenic paracrine mechanisms as a primary consequence of the used protocol. In vitro serum starvation (with or without VEGF present) appears to favour cardioprotection, extracellular matrix remodelling and blood vessel maturation relevant for the late maturation phase in infarct healing.

Optimization of culture condition of human bone marrow stromal cells in terms of purification, proliferation, and pluripotency

Human bone marrow stromal cells (hBMSCs) possess multilineage differentiation potential and play an important role in modern tissue engineering. However, the development of culture media to maintain hBMSCs in an undifferentiated, self-renewing state during their robust proliferation remains a challenge. We developed and tested modified growth medium [medium 1: epidermal growth factor (EGF), platelet-derived growth factor (PDGF), low glucose, 2% fetal calf serum (FCS)] on hBMSCs by comparing primary cell isolation, multipassage expansion, culture morphology, proliferation, and cellular phenotype, and performing an expression analysis of intrinsic-regulated genes to other two media. Cell morphology, proliferation, and phenotype varied among the media, while cells cultured in medium 1 displayed small, spindle-shaped morphology with the highest rate of growth capacities and the expected phenotype. RT-PCR analysis showed that medium 1 displayed the lowest expression levels of osteogenic genes, chondrogenic genes (osteonectin, runt-related transcription factor 2, cartilage oligo matrix protein, and SOX9), and adipogenic genes (lipoprotein lipase). The expression of another adipogenic gene, peroxisome proliferator-activator receptor-γ2, was higher in medium 1 but did not reach significance. In addition, hBMSCs expanded in medium 1 showed the highest expression ratio of self-renewing-related genes Krüppel-like factor 2 (KLF2) and KLF5. In conclusion, medium 1 allows for better expansion and pluripotency maintenance of hBMSCs and serves as a preferred alternative to traditional serum-containing media for research applications and future clinical use.

Identification of a common reference gene pair for qPCR in human mesenchymal stromal cells from different tissue sources treated with VEGF

Background

Human mesenchymal stromal cells from the bone marrow (BMSCs) are widely used as experimental regenerative treatment of ischemic heart disease, and the first clinical trials using adipose-derived stromal cells (ASCs) are currently being conducted. Regenerative mechanisms of BMSCs and ASCs are manifold and in vitro pretreatment of the cells with growth factors has been applied to potentially enhance these properties. When characterizing the transcriptional activity of these cellular mechanisms in vitro it is important to consider the effect of the growth factor treatment on reference genes (RGs) for the normalization of qPCR data.

Results

BMSCs and ASCs were stimulated with vascular endothelial growth factor A-165 (VEGF) for one week, and compared with un-stimulated cells from the same donor. The stability of nine RGs through VEGF treatment as well as the donor variation was assessed using the GenEx software with the subprograms geNorm and Normfinder.

The procedure of stepwise elimination was validated by poor performance of eliminated RGs in a normalization experiment using vWF as target gene. Normfinder found the TATA box binding protein (TBP) to be the most stable single RG for both BMSCs and ASCs. The optimal number of RGs for ASCs was two, and the lowest variance for vWF normalization was found using TBP and YWHAZ. For BMSCs, the optimal number of RGs was four, while the two-RG combination producing the most similar results was TBP and YWHAZ.

Conclusions

A common reference gene, TBP, was found to be the most stable standalone gene, while TBP and YWHAZ were found to be the best two-RG combination for qPCR analyses for both BMSCs and ASCs through the VEGF stimulation. The presented stepwise elimination procedure was validated, while we found the final normalization experiment to be essential.

Serum and supplement optimization for EU GMP-compliance in cardiospheres cell culture

Cardiac progenitor cells (CPCs) isolated as cardiospheres (CSs) and CS-derived cells (CDCs) are a promising tool for cardiac cell therapy in heart failure patients, having CDCs already been used in a phase I/II clinical trial. Culture standardization according to Good Manufacturing Practices (GMPs) is a mandatory step for clinical translation. One of the main issues raised is the use of xenogenic additives (e.g. FBS, foetal bovine serum) in cell culture media, which carries the risk of contamination with infectious viral/prion agents, and the possible induction of immunizing effects in the final recipient. In this study, B27 supplement and sera requirements to comply with European GMPs were investigated in CSs and CDCs cultures, in terms of process yield/efficiency and final cell product gene expression levels, as well as phenotype. B27− free CS cultures produced a significantly reduced yield and a 10-fold drop in c-kit expression levels versus B27+ media. Moreover, autologous human serum (aHS) and two different commercially available GMP AB HSs were compared with standard research-grade FBS. CPCs from all HSs explants had reduced growth rate, assumed a senescent-like morphology with time in culture, and/or displayed a significant shift towards the endothelial phenotype. Among three different GMP gamma-irradiated FBSs (giFBSs) tested, two provided unsatisfactory cell yields, while one performed optimally, in terms of CPCs yield/phenotype. In conclusion, the use of HSs for the isolation and expansion of CSs/CDCs has to be excluded because of altered proliferation and/or commitment, while media supplemented with B27 and the selected giFBS allows successful EU GMP-complying CPCs culture.

Autotransplantation of mesenchymal stromal cells from bone-marrow to heart in patients with severe stable coronary artery disease and refractory angina--final 3-year follow-up

BACKGROUND

The study assessed long-term safety and efficacy of intramyocardial injection of autologous bone-marrow derived mesenchymal stromal cells (BMMSCs) in patients with severe stable coronary artery disease (CAD) and refractory angina.

METHODS

Thirty-one patients with severe stable CAD and refractory angina were included. Patients had reversible myocardial ischemia and no further revascularization options. Autologous BMMSCs were isolated, culture expanded and stimulated with vascular endothelial growth-factor to facilitate endothelial differentiation. BMMSCs were injected into an ischemic, viable region of the myocardium. Patients were followed for 3 years.

RESULTS

We found significant clinical improvements in exercise time (p=0.0016), angina class (CCS) (p<0.0001), weekly number of angina attacks (p<0.0001) and use of nitroglycerine from (p=0.0017). In the Seattle Angina Questionnaire there were significant improvements in physical limitation score, angina stability score, angina frequency score and quality of life score (all p<0.0001). When comparing all hospital admissions from 3 years before to 3 years after treatment, we observed highly reduced admission rates for stable angina (p<0.0001), revascularization (p=0.003) and overall cardiovascular disease (p<0.0001). No early or late side-effects of the treatment were observed.

CONCLUSIONS

The final 3-year follow-up data after intramyocardial injection of autologous BMMSCs, in patients with severe CAD and refractory angina, demonstrated sustained clinical effects, reduced hospital admissions for cardiovascular disease and excellent long-term safety. The results indicate that autotransplantation of BMMSCs to the heart does not only improve symptoms but also slows down disease progression.

Serum-free media for the production of human mesenchymal stromal cells: a review

The regenerative potential of mesenchymal stromal cells (MSC) holds great promise in using them for treatment of a wide range of debilitating diseases. Several types of culture media and systems have been used for large-scale expansion of MSCs in vitro; however, the majority of them rely heavily on using foetal bovine serum (FBS)-supplement for optimal cell proliferation. FBS-based cultures pose the potential threat of spread of transmissible spongiform encephalopathy and bovine spongiform encephalopathy to MSCs and then to their recipients. A recent trend in cell culture is to change from serum-use to serum-free media (SFM). In this context, the current review focuses specifically on employment of various SFM for MSCs and discusses existences of various options with which to substitute FBS. In addition, we analyse MSC population growth kinetic patterns using various SFM for large-scale production of MSCs.

Identical effects of VEGF and serum-deprivation on phenotype and function of adipose-derived stromal cells from healthy donors and patients with ischemic heart disease

BACKGROUND

Adipose-derived stromal cells (ASCs) stimulated with vascular endothelial growth factor (VEGF) and serum-deprived, are applied in the first in-man double-blind placebo-controlled MyStromalCell Trial, as a novel therapeutic option for treatment of ischemic heart disease (IHD). This in vitro study explored the effect of VEGF and serum deprivation on endothelial differentiation capacity of ASCs from healthy donors and IHD patients.

METHODS

ASCs stimulated with rhVEGF(A165) in serum-deprived medium for one to three weeks were compared with ASCs in serum-deprived (2% fetal bovine serum) or complete medium (10% fetal bovine serum). Expression of VEGF receptors, endothelial and stem cell markers was measured using qPCR, flow cytometry and immunocytochemistry. In vitro tube formation and proliferation was also measured.

RESULTS

ASCs from VEGF-stimulated and serum-deprived medium significantly increased transcription of transcription factor FOXF1, endothelial marker vWF and receptor VEGFR1 compared with ASCs from complete medium. ASCs maintained stem cell characteristics in all conditions. Tube formation of ASCs occurred in VEGF-stimulated and serum-deprived medium. The only difference between healthy and patient ASCs was a variation in proliferation rate.

CONCLUSIONS

ASCs from IHD patients and healthy donors proved equally inclined to differentiate in endothelial direction by serum-deprivation, however with no visible additive effect of VEGF stimulation. The treatment did not result in complete endothelial differentiation, but priming towards endothelial lineage.

Different culture media affect growth characteristics, surface marker distribution and chondrogenic differentiation of human bone marrow-derived mesenchymal stromal cells

Background

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) play an important role in modern tissue engineering, while distinct variations of culture media compositions and supplements have been reported. Because MSCs are heterogeneous regarding their regenerative potential and their surface markers, these parameters were compared in four widely used culture media compositions.

Methods

MSCs were isolated from bone marrow and expanded in four established cell culture media. MSC yield/1000 MNCs, passage time and growth index were observed. In P4, typical MSC surface markers were analysed by fluorescence cytometry. Additionally, chondrogenic, adipogenic and osteogenic differentiation potential were evaluated.

Results

Growth index and P0 cell yield varied importantly between the media. The different expansion media had a significant influence on the expression of CD10, CD90, CD105, CD140b CD146 and STRO-1. While no significant differences were observed regarding osteogenic and adipogenic differentiation, chondrogenic differentiation was superior in medium A as reflected by GAG/DNA content.

Conclusions

The choice of expansion medium can have a significant influence on growth, differentiation potential and surface marker expression of mesenchymal stromal cells, which is of fundamental importance for tissue engineering procedures.

Pooled human platelet lysate versus fetal bovine serum-investigating the proliferation rate, chromosome stability and angiogenic potential of human adipose tissue-derived stem cells intended for clinical use

BACKGROUND AIMS

Because of an increasing focus on the use of adipose-derived stem cells (ASCs) in clinical trials, the culture conditions for these cells are being optimized. We compared the proliferation rates and chromosomal stability of ASCs that had been cultured in Dulbecco's modified Eagle's Medium (DMEM) supplemented with either pooled human platelet lysate (pHPL) or clinical-grade fetal bovine serum (FBS) (DMEM(pHPL) versus DMEM(FBS)).

METHODS

ASCs from four healthy donors were cultured in either DMEM(pHPL) or DMEM(FBS), and the population doubling time (PDT) was calculated. ASCs from two of the donors were expanded in DMEM(pHPL) or DMEM(FBS) and cultured for the final week before harvesting with or without the addition of vascular endothelial growth factor. We assessed the chromosomal stability (through the use of array comparative genomic hybridization), the expression of ASC and endothelial surface markers and the differentiation and angiogenic potential of these cells.

RESULTS

The ASCs that were cultured in pHPL exhibited a significantly shorter PDT of 29.6 h (95% confidence interval, 22.3-41.9 h) compared with those cultured in FBS, for which the PDT was 123.9 h (95% confidence interval, 95.6-176.2 h). Comparative genomic hybridization analyses revealed no chromosomal aberrations. Cell differentiation, capillary structure formation and cell-surface marker expression were generally unaffected by the type of medium supplement that was used or by the addition of vascular endothelial growth factor.

CONCLUSIONS

We observed that the use of pHPL as a growth supplement for ASCs facilitated a significantly higher proliferation rate compared with FBS without compromising genomic stability or differentiation capacity.

Comparison of the effects between animal-derived trypsin and recombinant trypsin on human skin cells proliferation, gene and protein expression

Animal-derivative free reagents are preferred in skin cell culture for clinical applications. The aim of this study was to compare the performance and effects between animal-derived trypsin and recombinant trypsin for skin cells culture and expansion. Full thickness human skin was digested in 0.6 % collagenase for 6 h to liberate the fibroblasts, followed by treatment with either animal-derived trypsin; Trypsin EDTA (TE) or recombinant trypsin; TrypLE Select (TS) to liberate the keratinocytes. Both keratinocytes and fibroblasts were then culture-expanded until passage 2. Trypsinization for both cell types during culture-expansion was performed using either TE or TS. Total cells yield was determined using a haemocytometer. Expression of collagen type I, collagen type III (Col-III), cytokeratin 10, and cytokeratin 14 genes were quantified via RT-PCR and further confirmed with immunocytochemical staining. The results of our study showed that the total cell yield for both keratinocytes and fibroblasts treated with TE or TS were comparable. RT-PCR showed that expression of skin-specific genes except Col-III was higher in the TS treated group compared to that in the TE group. Expression of proteins specific to the two cell types were confirmed by immunocytochemical staining in both TE and TS groups. In conclusion, the performance of the recombinant trypsin is comparable with the well-established animal-derived trypsin for human skin cell culture expansion in terms of cell yield and expression of specific cellular markers.

Rationale and design of the first randomized, double-blind, placebo-controlled trial of intramyocardial injection of autologous bone-marrow derived Mesenchymal Stromal Cells in chronic ischemic Heart Failure (MSC-HF Trial)

BACKGROUND

Stem cell therapy is an emerging treatment modality in cardiovascular disease. The best cell type and delivery method in different cardiovascular diseases remain to be determined.

STUDY DESIGN

The MSC-HF trial is a phase 2, single-center, double-blind, randomized, placebo-controlled trial of intramyocardial delivery of autologous bone-marrow derived mesenchymal stromal cells (MSCs) in patients with chronic ischemic heart failure. A total of 60 patients will be randomized in a 2:1 pattern to receive intramyocardial injections of either MSCs or placebo. Patients will be followed up for 12 months.

METHODS

Bone marrow will be obtained by aspiration from the iliac crest. Mesenchymal stromal cells will be isolated, and culture will be expanded for 6 to 8 weeks. A total of 12 to 15 MSC or placebo injections will be placed in an ischemic viable region of the myocardium using the electromechanical NOGA-XP system (Biologics Delivery Systems Group, Johnson & Johnson, Irwindale, CA).

ENDPOINTS

The primary endpoint is change in left ventricle end-systolic volume, measured by magnetic resonance imaging (MRI) or computed tomography (CT) at 6-month follow-up. Secondary endpoints are left ventricle ejection fraction, ventricular volumes, wall thickness, and systolic wall thickening measured by MRI or CT in addition to measurement of myocardial scar tissue by MRI. Other secondary endpoints are safety of treatment, clinical symptoms and functional capacity, weekly angina attacks, use of short-term nitroglycerine, and quality of life.

CONCLUSION

A randomized, double-blind, placebo-controlled, clinical trial of intramyocardial delivery of MSCs in patients with ischemic heart failure has been set up to confirm the positive findings in open-labeled clinical trials.

Angiogenesis potential of human limbal stromal niche cells

PURPOSE

The perivascular localization of stem cell (SC) niches suggests the presence of a vascular niche. We aimed to determine the angiogenesis potential of limbal niche cells (NCs).

METHODS

Human limbal NCs were isolated and serially passaged on plastic or coated Matrigel in embryonic SC medium containing BFGF and leukemia inhibitory factor before being reseeded in 3D Matrigel. Expression of angiogenesis markers was assessed by RT-qPCR and immunofluorescence staining. Their angiogenesis potential was measured by differentiation into vascular endothelial cells and by supporting vascular tube network formed by human umbilical vein endothelial cells (HUVEC) on Matrigel. Their support of limbal epithelial progenitor cells (LEPC) was examined in sphere growth formed by reunion in 3D Matrigel.

RESULTS

On plastic, limbal NC could be cultured only up to four passages before turning into myofibroblasts. In contrast, on coated Matrigel, they could be expanded for up to 12 passages with upregulation of markers suggestive of angiogenesis progenitors when reseeded in 3D Matrigel because they could differentiate into vascular endothelial cells and pericytes stabilizing the tube network formed by HUVEC. Although both expanded limbal NCs and HUVEC rejoined with LEPC to form spheres to upregulate expression of ΔNp63α, CK15, and CEBPδ, the former but not the latter abolished expression of CK12 keratin.

CONCLUSIONS

Human limbal NCs continuously expanded on the basement membrane differentiate into angiogenesis progenitors that prevent differentiation of LEPC/SCs. They may partake in formation of the vascular niche and contribute to angiogenesis during wound healing.

Adipose-derived mesenchymal stromal cells for chronic myocardial ischemia (MyStromalCell Trial): study design

Adipose tissue represents an abundant, accessible source of multipotent adipose-derived stromal cells (ADSCs). Animal studies have suggested that ADSCs have the potential to differentiate in vivo into endothelial cells and cardiomyocytes. This makes ADSCs a promising new cell source for regenerative therapy to replace injured tissue by creating new blood vessels and cardiomyocytes in patients with chronic ischemic heart disease. The aim of this special report is to review the present preclinical data leading to clinical stem cell therapy using ADSCs in patients with ischemic heart disease. In addition, we give an introduction to the first-in-man clinical trial, MyStromalCell Trial, which is a prospective, randomized, double-blind, placebo-controlled study using culture-expanded ADSCs obtained from adipose-derived cells from abdominal adipose tissue and stimulated with VEGF-A165 the week before treatment.

Direct intramyocardial mesenchymal stromal cell injections in patients with severe refractory angina: one-year follow-up

In patients with stable coronary artery disease (CAD) and refractory angina, we performed direct intramyocardial injections of autologous mesenchymal stromal cells (MSC) and followed the safety and efficacy of the treatment for 12 months. A total of 31 patients with stable CAD, moderate to severe angina, normal left ventricular ejection fraction, and no further revascularization options were included. Bone marrow MSCs were isolated and culture expanded for 6-8 weeks and then stimulated with vascular endothelial growth factor (VEGF) for 1 week. The 12-month follow-up demonstrated that it was safe to culture expand MSCs and use the cells for clinical treatment. The patients' maximal metabolic equivalent (MET) during exercise increased from 4.23 MET at baseline to 4.72 MET at 12-month follow-up (p < 0.001), Canadian Cardiovascular Society Class (CCS) was reduced from 3.0 to 0.8 (p < 0.001), angina attacks per week from 13.8 to 3.2 (p < 0.001), and nitroglycerin consumption from 10.7 to 3.4 per week (p < 0.001). In addition, Seattle Angina Questionnaire (SAQ) evaluations demonstrated highly significant improvements in physical limitation, angina stability, angina frequency, and quality of life (p < 0.001 for all). It is safe in the intermediate/long term to treat patients with stable CAD using autologous culture expanded MSCs. Previously reported, early and highly significant improvements in exercise capacity and clinical symptoms persist after 12 months. The results are encouraging, and a larger controlled study is warranted.

Isolation of hofbauer cells from human term placentas with high yield and purity

PROBLEM  Placental villus macrophages (i.e., Hofbauer cells, HBCs) were identified more than 100 years ago. Alterations in their numbers and characteristics are associated with several complications of pregnancy. Although HBCs have previously been isolated and cultured, there is no consensus methodology to obtain these cells with high yield and purity for in vitro studies. METHOD OF STUDY  Hofbauer cells were isolated from human term placentas using protocols in which cytotrophoblasts (CTs) and fibroblasts (FIBs), other major villous cell types, were isolated in parallel. Enzymatic digestion, Percoll gradients, and immunoselection were used to isolate the three cell types. Purity was assessed by morphology, flow cytometry, and phagocytosis assays. RESULTS  Hofbauer cells were isolated with 98-99% purity and a yield of 130-200 × 10(6) cells/80-100 g of tissue. HBCs exhibited a pleiomorphic and vacuolated appearance for at least 5 days in culture medium with and without serum. High levels of phagocytosis in HBCs, but not in CTs or FIBs, confirmed macrophage function in HBCs. Phagocytotic activity was maintained across several days in culture. CONCLUSION  Hofbauer cells were isolated from term placenta with high yield and purity using protocols in which CTs and FIBs were also obtained. This methodology will foster future studies that examine the role of HBCs in regulating villus function.

Mesenchymal stromal cell derived endothelial progenitor treatment in patients with refractory angina

AIMS

We evaluated the feasibility, safety and efficacy of intra-myocardial injection of autologous mesenchymal stromal cells derived endothelial progenitor cell (MSC) in patients with stable coronary artery disease (CAD) and refractory angina in this first in man trial.

METHODS AND RESULTS

A total of 31 patients with stable CAD, moderate to severe angina and no further revascularization options, were included. Bone marrow MSC were isolated and culture expanded for 6-8 weeks. It was feasible and safe to establish in-hospital culture expansion of autologous MSC and perform intra-myocardial injection of MSC. After six months follow-up myocardial perfusion was unaltered, but the patients increased exercise capacity (p < 0.001), reduction in CCS Class (p < 0.001), angina attacks (p < 0.001) and nitroglycerin consumption (p < 0.001), and improved Seattle Angina Questionnaire (SAQ) evaluations (p < 0.001). For all parameters there was a tendency towards improved outcome with increasing numbers of cells injected. In the MRI substudy: ejection fraction (p < 0.001), systolic wall thickness (p = 0.03) and wall thickening (p = 0.03) all improved.

CONCLUSIONS

The study demonstrated that it was safe to treat patients with stable CAD with autologous culture expanded MSC. Moreover, MSC treated patients had significant improvement in left ventricular function and exercise capacity, in addition to an improvement in clinical symptoms and SAQ evaluations.

Stem cells therapy for cardiovascular repair in ischemic heart disease: How to predict and secure optimal outcome?

Coronary artery disease is a growing problem worldwide. Early treatment with stabilizing drugs and revascularization by percutaneous coronary intervention or by-pass surgery has reduced the mortality significantly, but it is still the most common cause of death and a major cause of hospital admissions in industrialized countries. Treatment with stem cells with the potential to regenerate the damaged myocardium is a relatively new approach. However, the results from clinical studies on stem cell therapy for cardiac regeneration in patients with acute or chronic ischemic heart disease have been inconsistent. Some of the discrepancy could be due differences in study designs or patient selection. The review will based on conducted clinical stem cell trials try to elucidate how to predict and personalize this new treatment approach.

Human mesenchymal stromal cells preserve their stem features better when cultured in the Dulbecco's modified Eagle medium

BACKGROUND AIMS

The human mesenchymal stromal cell (hMSC), a type of adult stem cell with a fibroblast-like appearance, has the potential to differentiate along the mesenchymal lineage and also along other cell lineages. These abilities make hMSC a promising candidate for use in regenerative medicine. As the hMSC represents a very rare population in vivo, in vitro expansion is necessary for any clinical use. hMSC characterization is commonly carried out through the expression of specific markers and by the capability of differentiating toward at least adipo-, osteo- and chondrocytic lineages. Commitment processes also result in significant changes in the ultrastructure in order to acquire new functional abilities; however, few studies have dealt with the ultrastructural characteristics of hMSC according to the time of incubation and type of media.

METHODS

The immunophenotype, functional characteristics and ultrastructural features of bone marrow (BM) hMSC cultured in two different media were investigated. The media chosen were Iscove's modified Dulbecco's medium (IMDM) and the Dulbecco's modified Eagle medium (DMEM). The latter has been recommended recently by two international transplantation and cytotherapy societies, the International Society of Cellular Therapy (ISCT) and European Group for Blood and Bone Marrow Transplantation (EBMT), for hMSC expansion for clinical applications.

RESULTS AND CONCLUSIONS

The present results indicate that culture conditions greatly influence hMSC ultrastructural features, proliferation, growth and differentiation. In particular, our findings demonstrate that DMEM preserves the hMSC stem features better. Furthermore, the results obtained in IMDM suggest that a small size does not always correlate with conditions of cell immaturity and a greater proliferative potential.

Cryopreservation and revival of mesenchymal stromal cells

Over the past few years, the pace of preclinical stem cell research is astonishing and adult stem cells have become the subject of intense research. Due to the presence of promising supporting preclinical data, human clinical trials for stem cell regenerative treatment of various diseases have been initiated. As there has been a precedent for the use of bone marrow stem cells in the treatment of hematological malignancies and ischemic heart diseases through randomized clinical safety and efficacy trials, the development of new therapies based on culture-expanded human mesenchymal stromal cells (MSCs) opens up new possibilities for cell therapy. To facilitate these applications, cryopreservation and long-term storage of MSCs becomes an absolute necessity. As a result, optimization of this cryopreservation protocol is absolutely critical. The major challenge during cellular cryopreservation is the lethality associated with the cooling and thawing processes. The major objective is to minimize damage to cells during low temperature freezing and storage and the use of a suitable cryoprotectant. The detrimental effects of cellular cryopreservation can be minimized by controlling the cooling rate, using better cryoprotective agents, maintaining appropriate storage temperatures, and controlling the cell thawing rate. As is described in this chapter, human MSCs can either be frozen in cryovials or in freezing bags together with cryopreserve solutions containing dimethyl sulfoxide (DMSO).

Umbilical cord tissue-derived mesenchymal stem cells grow best under GMP-compliant culture conditions and maintain their phenotypic and functional properties

Mesenchymal stem cells (MSCs) are fibroblast-like multipotent stem cells that can differentiate into cell types of mesenchymal origin. Because of their immune properties and differentiation, potential MSCs are discussed for the use in tissue regeneration and tolerance induction in transplant medicine. This cell type can easily be obtained from the umbilical cord tissue (UCMSC) without medical intervention. Standard culture conditions include fetal bovine serum (FBS) which may not be approved for clinical settings. Here, we analyzed the phenotypic and functional properties of UCMSC under xeno-free (XF, containing GMP-certified human serum) and serum-free (SF) culture conditions in comparison with standard UCMSC cultures. Phenotypically, UCMSC showed no differences in the expression of mesenchymal markers or differentiation capacity. Functionally, XF and SF-cultured UCMSC have comparable adipogenic, osteogenic, and endothelial differentiation potential. Interestingly, the UCMSC-mediated suppression of T cell proliferation in an allogeneic mixed lymphocyte reaction (MLR) is more effective in XF and SF media than in standard FBS-containing cultures. Regarding the mechanism of action of MLR suppression, transwell experiments revealed that in neither UCMSC culture a direct cell-cell contact is necessary for inhibiting T cell proliferation, and that the major effector molecule is prostaglandin E₂ (PGE₂). Taken together, GMP-compliant growth media qualify for long-term cultures of UCMSC which is important for a future clinical study design in regenerative and transplant medicine.

Mesenchymal stromal cell and mononuclear cell therapy in heart disease

Despite progress in percutaneous coronary intervention, bypass surgery and drug therapy, rates of mortality and morbidity after acute coronary syndrome are high due to ventricular remodeling and heart failure. Mesenchymal stromal cells (MSCs) from adult bone marrow or adipose tissue are considered potential candidates for therapeutic regenerative treatment in cardiovascular disease. Recent animal studies have demonstrated that MSCs can induce neovascularization and improve myocardial function in postinfarction myocardial ischemic hearts. This review will focus on the present preclinical and clinical knowledge about the use of mononuclear cells and MSCs for cardiac regenerative medicine, the source of MSCs for clinical use and problems to consider when conducting clinical MSC therapy.

Concise review: mind the gap: challenges in characterizing and quantifying cell- and tissue-based therapies for clinical translation

There are many challenges associated with characterizing and quantifying cells for use in cell- and tissue-based therapies. From a regulatory perspective, these advanced treatments must not only be safe and effective but also be made by high-quality manufacturing processes that allow for on-time delivery of viable products. Although sterility assays can be adapted from conventional bioprocessing, cell- and tissue-based therapies require more stringent safety assessments, especially in relation to use of animal products, immune reaction, and potential instability due to extended culture times. Furthermore, cell manufacturers who plan to use human embryonic stem cells in their therapies need to be particularly stringent in their final purification steps, due to the unrestricted growth potential of these cells. This review summarizes the current issues in characterization and quantification for cell- and tissue-based therapies, dividing these challenges into the regulatory themes of safety, potency, and manufacturing quality. It outlines current assays in use, as well as highlights the limits of many of these product release tests. Mode of action is discussed, with particular reference to in vitro surrogate assays that can be used to provide information to correlate with proposed in vivo patient efficacy. Importantly, this review highlights the requirement for basic research to improve current knowledge on the in vivo fate of these treatments; as well as an improved stakeholder negotiation process to identify the measurement requirements that will ensure the manufacture of the best possible cell- and tissue-based therapies within the shortest timeframe for the most patient benefit.

Serial in vivo imaging of the porcine heart after percutaneous, intramyocardially injected 111In-labeled human mesenchymal stromal cells

This pilot trial aimed to investigate the utilization of (111)In-labeling of mesenchymal stromal cells (MSC) for in vivo tracking after intramyocardial transplantation in a xenotransplantation model with gender mismatched cells. Human male MSC were expanded ex vivo and labeled with (111)In-tropolone. Ten female pigs were included. The labeled cells were transplanted intramyocardially using a percutaneous injection system. The (111)In activity was determined using gamma camera imaging. Excised hearts were analyzed by fluorescence in situ hybridization (FISH) and microscopy. Gamma camera imaging revealed focal cardiac (111)In accumulations up to 6 days after injection (N = 4). No MSC could be identified with FISH, and microscopy identified widespread acute inflammation. Focal (111)In accumulation, inflammation but no human MSC were similarly seen in pigs (N = 2) after immunosuppression. A comparable retention of (111)In activity was observed after intramyocardial injection of (111)In-tropolone (without cells) (N = 2), but without sign of myocardial inflammation. Injection of labeled non-viable cells (N = 1) also led to high focal (111)In activity up to 6 days after intramyocardial injection. As a positive control of the FISH method, we identified labeled cells both in culture and immediately after cell injection in one pig. This pilot trial suggests that after intramyocardial injection (111)In stays in the myocardium despite possible disappearance of labeled cells. This questions the clinical use of (111)In-labeled cells for tracking. The results further suggest that xenografting of human MSC into porcine hearts leads to inflammation contradicting previous studies implying a special immunoprivileged status for MSC.

CD90 Expression on human primary cells and elimination of contaminating fibroblasts from cell cultures

Cluster Differentiation 90 (CD90) is a cell surface glycoprotein originally identified on mouse thymocytes. Although CD90 has been identified on a variety of stem cells and at varying levels in non-lymphoid tissues such as on fibroblasts, brain cells, and activated endothelial cells, the knowledge about the levels of CD90 expression on different cell types, including human primary cells, is limited. The goal of this study was to identify CD90 as a human primary cell biomarker and to develop an efficient and reliable method for eliminating unwanted or contaminating fibroblasts from human primary cell cultures suitable for research pursuant to cell based therapy technologies.

Timing of granulocyte-colony stimulating factor treatment after acute myocardial infarction and recovery of left ventricular function: results from the STEMMI trial

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) therapy after ST-elevation myocardial infarction (STEMI) have not demonstrated impact on systolic recovery compared to placebo. However, recent studies suggest that timing of G-CSF therapy is crucial.

METHODS

Timing of G-CSF treatment was analyzed in the STEMMI MRI subpopulation including 54 patients with STEMI treated with primary percutaneous coronary intervention (PCI) <12 h after symptom onset. Patients were randomized to double blind treatment with G-CSF (10 microg/kg/day) or placebo. Treatment was initiated from 17 to 65 h (mean 30) after PCI. Left ventricular ejection fraction (LVEF) was evaluated with MRI.

RESULTS

Recovery of LVEF from baseline to 6 months was not associated with time from PCI to G-CSF. An identical improvement in LVEF was found in the placebo group and the G-CSF group (p=0.8). There was no correlation between time from PCI to G-CSF and maximum plasma concentration of CD34+ cells (r=-0.3, p=0.1). Similar results were found from data on recovery of the infarction size and change in the systolic wall thickening.

CONCLUSIONS

In the time window from 17 to 65 h after STEMI treated with PCI, the timing of G-CSF treatment does not seem to affect the recovery of LVEF. It remains to be determined if very early, or very late G-CSF treatment might be effective.