Stem cells derived from amniotic fluid: new potentials in regenerative medicine

DNA concentrations in amniotic fluid according to gestational age and fetal sex: data from 2573 samples

PURPOSE

In some cases of prenatal genetic testing, an ample amount of fetal DNA is needed, to allow for parallel testing (conducting several genetic tests simultaneously). This study investigated the association between amniotic fluid DNA concentration and various factors. We aimed to define the required amount of amniotic fluid to be extracted in amniocentesis, to allow parallel testing throughout gestational weeks.

METHODS

DNA concentration was analyzed from amniocentesis samples taken during the years 2016-2022. Sex association was also analyzed in postnatal whole blood samples from a separate cohort. Theoretical minimum volume of amniotic fluid needed to ensure enough DNA for chromosomal microarray analysis and exome sequencing was calculated.

RESULTS

We focused our analysis on 2573 samples, which were taken during weeks 17-23 and 30-35. DNA concentrations increased from weeks 17 to 21, with relatively stable concentrations thereafter. Significantly higher DNA concentrations were seen in pregnancies of female fetuses. DNA concentrations in postnatal whole blood samples did not show this association. Across most weeks, the volume needed to extract 2 µg of DNA from 95% of the samples was about 34 ml.

CONCLUSION

DNA concentrations in amniotic fluid vary according to gestational age and are higher in pregnancies of female fetuses. This should be considered when determining the volume of fluid extracted and the timing of amniocentesis, with greater volumes needed in earlier stages of pregnancy.

Mesenchymal Stem Cells and Secretome as a New Possible Approach to Treat Cartilage Damage: An In Vitro Study

Introduction: Osteoarthritis is a degenerative condition of the cartilage, often common among the population and occurs frequently with aging. Many factors are decisive for the development of its pathogenesis such as age, obesity, trauma, mechanical load, and modification of synovial biology. The main features of osteoarthritis are chondrocytes and cartilage matrix loss, which lead to pain, loss of function of the whole joint, and disability, representing a relevant health problem. Recently, a new therapeutic approach based on cell therapy has been studying the regenerative ability of mesenchymal stem cells for osteoarthritic chondrocytes. Aim: This in vitro study clarifies the regenerative effects of multipotent adipose-derived stem cells and the pluripotent amniotic epithelial stem cells on arthrosis chondrocytes by performing co-culture experiments. Methods: We studied the regenerative potential of secretome (soluble factors and extracellular vesicles), mesenchymal stem cells, and the adipose stromal vascular fraction. The regenerative effects were evaluated by gene and protein expression analysis of articular cartilage-specific genes and proteins like col2a1, acan, and sox9. Results: Mesenchymal stem cells, secretome, and adipose stromal vascular fractions influenced the cartilage genes and protein expression. Conclusions: The results indicate that the treatment with mesenchymal stem cells could be the best biological approach for cartilage regenerative medicine.

Mining human clinical waste as a rich source of stem cells for neural regeneration

Neural diseases are challenging to treat and are regarded as one of the major causes of disability and morbidity in the world. Stem cells can provide a solution, by offering a mechanism to replace damaged circuitry. However, obtaining sufficient cell sources for neural regeneration remains a significant challenge. In recent years, waste-derived stem(-like) cells (WDS-lCs) extracted from both prenatal and adult clinical waste tissues/products, have gained increasing attention for application in neural tissue repair and remodeling. This often-overlooked pool of cells possesses favorable characteristics; including self-renewal, neural differentiation, secretion of neurogenic factors, cost-effectiveness, and low ethical concerns. Here, we offer a perspective regarding the biological properties, extraction protocols, and preclinical and clinical treatments where prenatal and adult WDS-lCs have been utilized for cell replacement therapy in neural applications, and the challenges involved in optimizing these approaches toward patient led therapies.

Utilizing stem cell-secreted molecules as a versatile toolbox for skin regenerative medicine

Stem cells are recognized as an important target and tool in regenerative engineering. In this study, we explored the feasibility of engineering amniotic fluid-derived mesenchymal stem cell-secreted molecules (afMSC-SMs) as a versatile bioactive material for skin regenerative medicine applications in a time- and cost-efficient and straightforward manner. afMSC-SMs, obtained in powder form through ethanol precipitation, effectively contributed to preserving the self-renewal capacity and differentiation potential of primary human keratinocytes (pKCs) in a xeno-free environment, offering a potential alternative to traditional culture methods for their long-term in vitro expansion, and allowed them to reconstitute a fully stratified epithelium sheet on human dermal fibroblasts. Furthermore, we demonstrated the flexibility of afMSC-SMs in wound healing and hair regrowth through injectable hydrogel and nanogel-mediated transdermal delivery systems, respectively, expanding the pool of regenerative applications. This cell-free approach may offer several potential advantages, including streamlined manufacturing processes, scalability, controlled formulation, longer shelf lives, and mitigation of risks associated with living cell transplantation. Accordingly, afMSC-SMs could serve as a promising therapeutic toolbox for advancing cell-free regenerative medicine, simplifying their broad applicability in various clinical settings.

PCR Array Profiling of miRNA Expression Involved in the Differentiation of Amniotic Fluid Stem Cells toward Endothelial and Smooth Muscle Progenitor Cells

Differentiation of amniotic fluid stem cells (AFSCs) into multiple lineages is controlled by epigenetic modifications, which include DNA methylation, modifications of histones, and the activity of small noncoding RNAs. The present study investigates the role of miRNAs in the differentiation of AFSCs and addresses how their unique signatures contribute to lineage-specific differentiation. The miRNA profile was assessed in AFSCs after 4 weeks of endothelial and muscular differentiation. Our results showed decreased expression of five miRNAs (miR-18a-5p, miR-125b-5p, miR-137, miR-21-5p, and let-7a) and increased expression of twelve miRNAs (miR-134-5p, miR-103a-3p, let-7i-5p, miR-214-3p, let-7c-5p, miR-129-5p, miR-210-3p, let-7d-5p, miR-375, miR-181-5p, miR-125a-5p, and hsa-let-7e-5p) in endothelial progenitor cells (EPCs) compared with undifferentiated AFSCs. AFSC differentiation into smooth muscle revealed notable changes in nine out of the 84 tested miRNAs. Among these, three miRNAs (miR-18a-5p, miR-137, and sa-miR-21-5p) were downregulated, while six miRNAs (miR-155-5p, miR-20a-5p, let-7i-5p, hsa-miR-134-5p, hsa-miR-214-3p, and hsa-miR-375) exhibited upregulation. Insights from miRNA networks promise future advancements in understanding and manipulating endothelial and muscle cell dynamics. This knowledge has the potential to drive innovation in areas like homeostasis, growth, differentiation, and vascular function, leading to breakthroughs in biomedical applications and therapies.

Effect of the Enrichment in c-Kit Stem Cell Potential of Foetal Human Amniotic Fluid Cells: Characterization from Single Cell Analysis to the Secretome Content

Human amniotic fluid cells (hAFSCs) are a fascinating foetal cell-type that have important stem cell characteristics; however, they are a heterogeneous population that ranges from totally differentiated or progenitor cells to highly multipotent stem cells. There is no single approach to isolating the stem cell component, but the selection of a subpopulation of hAFSCs expressing c-Kit is widely employed, while a deep characterization of the two populations is still lacking. Here we performed single-cell and bulk RNAseq analysis to compare the gene expression profiles of adherent amniotic fluid cells and their subpopulation c-Kit⁺. Information deriving from this high throughput technology on the transcriptome was then confirmed for specific targets with protein expression experiments and functional analysis. In particular, transcriptome profiling identified changes in cellular distribution among the different clusters that correlated with significant differential expression in pathways related to stemness, proliferation, and cell cycle checkpoints. These differences were validated by RT-PCR, immunofluorescence, WB, and cell cycle assays. Interestingly, the two populations produced secretomes with different immune-modulating and pro-regenerative potentials. Indeed, the presence of TGFβ, HGF, IDO was higher in EVs deriving from c-Kit⁺ cells, unlike IL-6. These results suggest the existence of deep intra-population differences that can influence the stemness profile of hAFSCs. This study represents a proof-of-concept of the importance of selecting c-Kit positive fractions with higher potential in regenerative medicine applications.

Amniotic Fluid Stem Cells: What They Are and What They Can Become

In the last two decades, fetal amniotic fluid stem cells progressively attracted attention in the context of both basic research and the development of innovative therapeutic concepts. They exhibit broadly multipotent plasticity with the ability to differentiate into cells of all three embryonic germ layers and low immunogenicity. They are convenient to maintain, highly proliferative, genomically stable, non-tumorigenic, perfectly amenable to genetic modifications, and do not raise ethical concerns. However, it is important to note that among the various fetal amniotic fluid cells, only c-Kit+ amniotic fluid stem cells represent a distinct entity showing the full spectrum of these features. Since amniotic fluid additionally contains numerous terminally differentiated cells and progenitor cells with more limited differentiation potentials, it is of highest relevance to always precisely describe the isolation procedure and characteristics of the used amniotic fluid-derived cell type. It is of obvious interest for scientists, clinicians, and patients alike to be able to rely on up-todate and concisely separated pictures of the utilities as well as the limitations of terminally differentiated amniotic fluid cells, amniotic fluid-derived progenitor cells, and c-Kit+ amniotic fluid stem cells, to drive these distinct cellular models towards as many individual clinical applications as possible.

Single extracellular vesicle analysis in human amniotic fluid shows evidence of phenotype alterations in preeclampsia

Amniotic fluid surrounding the developing fetus is a complex biological fluid rich in metabolically active bio-factors. The presence of extracellular vesicles (EVs) in amniotic fluid has been mainly related to foetal urine. We here characterized EVs from term amniotic fluid in terms of surface marker expression using different orthogonal techniques. EVs appeared to be a heterogeneous population expressing markers of renal, placental, epithelial and stem cells. Moreover, we compared amniotic fluid EVs from normal pregnancies with those of preeclampsia, a hypertensive disorder affecting up to 8% of pregnancies worldwide. An increase of CD105 (endoglin) expressing EVs was observed in preeclamptic amniotic fluid by bead-based cytofluorimetric analysis, and further confirmed using a chip-based analysis. HLA-G, a typical placental marker, was not co-expressed by the majority of CD105+ EVs, in analogy with amniotic fluid stromal cell derived-EVs. At a functional level, preeclampsia-derived EVs, but not normal pregnancy EVs, showed an antiangiogenic effect, possibly due to the decoy effect of endoglin. Our results provide a characterization of term amniotic fluid-EVs, supporting their origin from foetal and placental cells. In preeclampsia, the observed antiangiogenic characteristics of amniotic fluid-EVs may reflect the hypoxic and antiangiogenic microenvironment and could possibly impact on the developing fetus or on the surrounding foetal membranes.

Placental Tissues as Biomaterials in Regenerative Medicine

Placental tissues encompass all the tissues which support fetal development, including the placenta, placental membrane, umbilical cord, and amniotic fluid. Since the 1990s there has been renewed interest in the use of these tissues as a raw material for regenerative medicine applications. Placental tissues have been extensively studied for their potential contribution to tissue repair applications. Studies have attributed their efficacy in augmenting the healing process to the extracellular matrix scaffolds rich in collagens, glycosaminoglycans, and proteoglycans, as well as the presence of cytokines within the tissues that have been shown to stimulate re-epithelialization, promote angiogenesis, and aid in the reduction of inflammation and scarring. The compositions and properties of all birth tissues give them the potential to be valuable biomaterials for the development of new regenerative therapies. Herein, the development and compositions of each of these tissues are reviewed, with focus on the structural and signaling components that are relevant to medical applications. This review also explores current configurations and recent innovations in the use of placental tissues as biomaterials in regenerative medicine.

Human amniotic fluid as a source of stem cells

Human amniotic fluid collected during amniocentesis contains a heterogeneous population of differentiated and undifferentiated cells. Properties and number of these cells vary depending on the gestational age and the presence of potential fetal pathologies. The aim of this study was to analyze the effects of maternal, fetal, and environmental factors on the success rates of amniotic fluid stem cell cultures, the number of human amniotic fluid stem cells (hAFSC), their growth rates in primary cultures, and the number of cell passages. The study included 355 patients qualified for genetic amniocentesis at the Prenatal Genetic Unit, Department of Obstetrics, Gynecology and Oncologic Gynecology, Nicolaus Copernicus University Medical College in Bydgoszcz in 2011–2017. The mean age of the study participants was 34 ± 6.2 years, and mean gravidity amounted to 2.48 ± 1.4. Amniotic fluid sample volume turned out to be a highly significant (p < 0.01) predictor of culture success, and the relationship was particularly evident in women older than 40 years. Another highly significant predictor of culture success was the presence of two cell populations in the sample (p < 0.01). The likelihood of culture success correlated significantly (p < 0.05) with the season of the year at the time of amniocentesis. The number of cell passages differed significantly depending on the maternal age (p < 0.01). The number of passages also showed a highly significant relationship with the season of the year the sample was obtained (p < 0.01). Younger maternal age was identified as a determinant of high passage number (≥3), and another highly significant determinant of high passage number was the presence of two cell populations in the amniotic fluid sample (p < 0.01). Percentage of successfully established hAFSC cultures and the number of passages depended on amniotic fluid volume, the presence of two cell populations within the sample, and the season of the year. Individual characteristics of the donors, such as age and gravidity, did not exert a significant effect on the number of isolated hAFSCs and the rate of their growth. Patients’ place of residence, fetal karyotype, transportation time, and purity of the samples did not affect the success rates for primary cultures and the number of passages.

Advancing Regenerative Cellular Therapies in Non-Scarring Alopecia

Alopecia or baldness is a common diagnosis in clinical practice. Alopecia can be scarring or non-scarring, diffuse or patchy. The most prevalent type of alopecia is non-scarring alopecia, with the majority of cases being androgenetic alopecia (AGA) or alopecia areata (AA). AGA is traditionally treated with minoxidil and finasteride, while AA is treated with immune modulators; however, both treatments have significant downsides. These drawbacks compel us to explore regenerative therapies that are relatively devoid of adverse effects. A thorough literature review was conducted to explore the existing proven and experimental regenerative treatment modalities in non-scarring alopecia. Multiple treatment options compelled us to classify them into growth factor-rich and stem cell-rich. The growth factor-rich group included platelet-rich plasma, stem cell-conditioned medium, exosomes and placental extract whereas adult stem cells (adipose-derived stem cell-nano fat and stromal vascular fraction; bone marrow stem cell and hair follicle stem cells) and perinatal stem cells (umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs), Wharton jelly-derived MSCs (WJ-MSCs), amniotic fluid-derived MSCs (AF-MSCs), and placental MSCs) were grouped into the stem cell-rich group. Because of its regenerative and proliferative capabilities, MSC lies at the heart of regenerative cellular treatment for hair restoration. A literature review revealed that both adult and perinatal MSCs are successful as a mesotherapy for hair regrowth. However, there is a lack of standardization in terms of preparation, dose, and route of administration. To better understand the source and mode of action of regenerative cellular therapies in hair restoration, we have proposed the "À La Mode Classification". In addition, available evidence-based cellular treatments for hair regrowth have been thoroughly described.

Multi-layered ZIF-coated cells for the release of bioactive molecules in hostile environments

Metal-organic framework (MOF) coatings on cells enhance viability in cytotoxic environments. Here, we show how protective multi-layered MOF bio-composite shells on a model cell system (yeast) enhance the proliferation of...

An Update on the Role of Extracellular Vesicles in the Pathogenesis of Necrotizing Enterocolitis and Inflammatory Bowel Diseases

Some of the most fundamental influences of microorganisms inhabiting the human intestinal tract are exerted during infant development and impact the maturation of intestinal mucosa and gut immune system. The impact of bacteria on the host gut immune system is partially mediated via released extracellular vesicles (EVs). The heterogeneity in EV content, size, and bacterial species origin can have an impact on intestinal cells, resulting in inflammation and an immune response, or facilitate pathogen entry into the gut wall. In mammals, maintaining the integrity of the gut barrier might also be an evolutionary function of maternal milk EVs. Recently, the usage of EVs has been explored as a novel therapeutic approach in several pathological conditions, including necrotizing enterocolitis (NEC) and inflammatory bowel disease (IBD). In this review, we attempt to summarize the current knowledge of EV biology, followed by a discussion of the role that EVs play in gut maturation and the pathogenesis of NEC and IBD.

Angiogenic Properties of Placenta-Derived Extracellular Vesicles in Normal Pregnancy and in Preeclampsia

Angiogenesis is one of the main processes that coordinate the biological events leading to a successful pregnancy, and its imbalance characterizes several pregnancy-related diseases, including preeclampsia. Intracellular interactions via extracellular vesicles (EVs) contribute to pregnancy's physiology and pathophysiology, and to the fetal-maternal interaction. The present review outlines the implications of EV-mediated crosstalk in the angiogenic process in healthy pregnancy and its dysregulation in preeclampsia. In particular, the effect of EVs derived from gestational tissues in pro and anti-angiogenic processes in the physiological and pathological setting is described. Moreover, the application of EVs from placental stem cells in the clinical setting is reported.

Accelerated wound closure: Systematic evaluation of cellulose acetate effects on biologically active molecules release from amniotic fluid stem cells

Despite a lot of intensive research on cell-scaffold interaction, the focus is mainly on the capacity of construct scaffolds to regulate cell mobility, migration, and cytotoxicity. The effect of the scaffold's topographical and material properties on the expression of biologically active compounds from stem cells is not well understood. In this study, the influence of cellulose acetate (CA) on the electrospinnability of gelatin and the roles of gelatin-cellulose acetate (Ge-CA) on modulating the release of biologically active compounds from amniotic fluid stem cells (AFSCs) is emphasized. It was found that the presence of a small amount of CA could provide a better microenvironment that mimics AFSCs' niche. However, a large amount of CA exhibited no significant effect on AFSCs migration and infiltration. Further study on the effect of surface topography and mechanical properties on AFSCs showed that the tailored microenvironment provided by the Ge-CA scaffolds had transduced physical cues to biomolecules released into the culture media. It was found that the AFSCs seeded on electrospun scaffolds with less CA proportions have profound effects on the secretion of metabolic compounds compared to those with higher CA contained and gelatin coating. The enhanced secretion of biologically active molecules by the AFSCs on the electrospun scaffolds was proven by the accelerated wound closure on the injured human dermal fibroblast (HDF) model. The rapid HDF cell migration could be anticipated due to a higher level of paracrine factors in AFSCs media. Our study demonstrates that the fibrous topography and mechanical properties of the scaffold are a key material property that modulates the high expression of biologically active compounds from the AFSCs. The discovery elucidates a new aspect of material functions and scaffolds material-AFSC interaction for regulating biomolecules release to promote tissue regeneration/repair. To the best of our knowledge, this is the first report describing the scaffolds material-AFSC interaction and the efficacy of scratch assays on quantifying the cell migration in response to the AFSCs metabolic products.

Recent Advances in Scaffolding from Natural-Based Polymers for Volumetric Muscle Injury

Volumetric Muscle Loss (VML) is associated with muscle loss function and often untreated and considered part of the natural sequelae of trauma. Various types of biomaterials with different physical and properties have been developed to treat VML. However, much work remains yet to be done before the scaffolds can pass from the bench to the bedside. The present review aims to provide a comprehensive summary of the latest developments in the construction and application of natural polymers-based tissue scaffolding for volumetric muscle injury. Here, the tissue engineering approaches for treating volumetric muscle loss injury are highlighted and recent advances in cell-based therapies using various sources of stem cells are elaborated in detail. An overview of different strategies of tissue scaffolding and their efficacy on skeletal muscle cells regeneration and migration are presented. Furthermore, the present paper discusses a wide range of natural polymers with a special focus on proteins and polysaccharides that are major components of the extracellular matrices. The natural polymers are biologically active and excellently promote cell adhesion and growth. These bio-characteristics justify natural polymers as one of the most attractive options for developing scaffolds for muscle cell regeneration.

Stem Cells as Therapy for Necrotizing Enterocolitis: A Systematic Review and Meta-Analysis of Preclinical Studies

Background: Necrotizing enterocolitis (NEC) is the most common life-threatening gastrointestinal condition among very and extremely preterm infants. Stem cell therapy has shown some promising protective effects in animal models of intestinal injury, including NEC, but no systematic review has yet evaluated the preclinical evidence of stem cell therapy for NEC prevention or treatment. Methods: PubMed and EMBASE databases were searched for studies using an animal model of NEC with stem cells or their products. The SYRCLE tool was used for the assessment of risk of bias. A random-effects model was used to pool odds ratios (ORs) and 95% confidence interval (CI). Results: We screened 953 studies, of which nine (eight rat and one mouse models) met the inclusion criteria. All animal models induced NEC by a combination of hypothermia, hypoxia, and formula feeding. Risk of bias was evaluated as unclear on most items for all studies included. Meta-analysis found that both mesenchymal and neural stem cells and stem cell-derived exosomes reduced the incidence of all NEC (OR 0.22, 95% CI 0.16-0.32, k = 16), grade 2 NEC (OR 0.41, 95% CI 0.24-0.70, k = 16), and grade 3-4 NEC (OR 0.28, 95% CI 0.19-0.42, k = 16). k represents the number of independent effect sizes included in each meta-analysis. The effect of the exosomes was similar to that of the stem cells. Stem cells and exosomes also improved 4-day survival (OR 2.89 95% CI 2.07-4.04, k = 9) and 7-day survival (OR 3.96 95% CI 2.39-6.55, k = 5) after experimental NEC. Meta-analysis also found that stem cells reduced other indicators of intestinal injury. Conclusion: The data from this meta-analysis suggest that both stem cells and stem cell-derived exosomes prevented NEC in rodent experimental models. However, unclear risk of bias and incomplete reporting underline that poor reporting standards are common and hamper the reliable interpretation of preclinical evidence for stem cell therapy for NEC.

Repair of rat cranial bone defect by using amniotic fluid-derived mesenchymal stem cells in polycaprolactone fibrous scaffolds and platelet-rich plasma

Introduction: Tissue regenerative medicine strategies, as a promising alternative has become of major interest to the reconstruction of critical size bone defects. This study evaluated the effects of the simultaneous application of polycaprolactone (PCL), amniotic fluid mesenchymal stem cells (AF-MSCs) and platelet-rich plasma (PRP) on the repair of rat cranial bone defects. Methods: The AF-MSCs were isolated at the end of the second week of pregnancy in rats. PRP obtained from rat blood and the random PCL fibrous scaffolds were prepared using the electrospinning method. Circular full thickness (5 mm) bone defects were developed on both sides of the parietal bones (animal number=24) and the scaffolds containing AF-MSCs and PRP were implanted in the right lesions. Thereafter, after eight weeks the histological and immunohistochemistry studies were performed to evaluate the bone formation and collagen type I expression. Results: The spindle-shaped mesenchymal stem cells were isolated and the electron microscope images indicated the preparation of a random PCL scaffold. Immunohistochemical findings showed that collagen type I was expressed by AF-MSCs cultured on the scaffold. The results of hematoxylin and eosin (H&E) staining indicated the formation of blood vessels in the presence of PRP. Additionally, immunofluorescence findings suggested that PRP had a positive effect on collagen type I expression. Conclusion: The simultaneous application of fibrous scaffold + AF-MSCs + PRP has positive effects on bone regeneration. This study showed that PRP can affect the formation of new blood vessels in the scaffold transplanted in the bone defect.

Harnessing the mesenchymal stem cell secretome for regenerative urology

The extensive arsenal of bioactive molecules secreted by mesenchymal stem cells (MSCs), known as the secretome, has demonstrated considerable therapeutic benefit in regenerative medicine. Investigation into the therapeutic potential of the secretome has enabled researchers to replicate the anti-inflammatory, pro-angiogenic and trophic effects of stem cells without the need for the cells themselves. Furthermore, treatment with the MSC secretome could circumvent hurdles associated with cellular therapy, including oncogenic transformation, immunoreactivity and cost. Thus, a clear rationale exists for investigating the therapeutic potential of the MSC secretome in regenerative urology. Indeed, preclinical studies have demonstrated the therapeutic benefits of the MSC secretome in models of stress urinary incontinence, renal disease, bladder dysfunction and erectile dysfunction. However, the specific mechanisms underpinning therapeutic activity are unclear and require further research before clinical translation. Improvements in current proteomic methods used to characterize the secretome will be necessary to provide further insight into stem cells and their secretome in regenerative urology.

Molecular characterization of bovine amniotic fluid derived stem cells with an underlying focus on their comparative neuronal potential at different passages

BACKGROUND

The excellence in the field of stem cell therapy demands alternative and more convenient stem cells for potential applications. Researchers have opted for least invasive and broadly multipotent cells with minimum ethical concerns. Bovine amniotic fluid derived mesenchymal stem cells (BAF-MSCs) due to their ease of collection and owing similar gestational length to that of human could be presumed as an attractive large animal model for biomedical and biotechnology research.

METHODS

Bovine amniotic fluid derived stem cells were isolated from abattoir based samples and characterized for epithelial, neuronal, mesenchymal and pluripotent markers by qPCR and immunofluorescence studies at P1, P3, P5 and P7 alongside population doubling time, growth curve and multilineage differentiation studies.

RESULTS

The cells were explored for unique expression of Sox2, which was observed to be up regulated with increase in passage number and Nestin was found to be downregulated during further passaging of mesenchymal cells in this study. The cells also co-expressed Oct ¾ at initial passages which diminished within further passages. Evidence regarding diversity and heterogeneity in different cell population in amniotic fluid was recorded by positive expression of epithelial cell markers like pan Cytokeratin and p63 during early passages. The study suggested that cells with higher expression of Sox2 generated comparatively larger neurospheres with comparative strong expression of Sox2 and Nestin by immunofluorescence staining and qPCR analysis. Besides BAF-MSCs derived neurospheres were also shown to express pro-neuronal markers like ß-III Tubulin, GAP43 and ASCL-1.

CONCLUSIONS

This study explores and characterizes BAF-MSCs for their multipotent and neurogenic potentials and their use for clinical applications, though more detailed studies are needed to determine the exact pathways linked with neurogenic capacities of these cells and their morphological assessments at different gestational ages in bovines. The knowledge from the bovine model after detailed studies, proven safety and efficacy could also be used to understand substitutive strategies to investigate MSCs physiology at different trimesters and potential application of these cells for human and veterinary regenerative medicine provided the animal ethics are carefully monitored.

Epigenetic regulation of amniotic fluid mesenchymal stem cell differentiation to the mesodermal lineages at normal and fetus-diseased gestation

Human mesenchymal stem cells isolated from amniotic fluid (AF-MSCs) demonstrate the potency for self-renewal and multidifferentiation, and can, therefore, be a potential alternative source of stem cells adapted for therapeutic purposes. The object of this study is to evaluate the efficacy of MSCs from AF when the pregnancy is normal or when the fetus is affected during pregnancy to differentiate into mesodermal lineage tissues and to elucidate epigenetic states responsible for terminal adipogenic and osteogenic differentiation. The morphology of AF-MSCs from two cell sources and the expression of the cell surface-specific (CD44, CD90, and CD105) markers and pluripotency (Oct4, Nanog, Sox2, and Rex1) genes were quite similar and underwent mesodermal lineage differentiation because this is shown by the typical cell morphology and of genes' expression specific for adipogenic (peroxisome proliferator-activated receptor-ɣ, adiponectin) and osteoblastic (alkaline phosphatase, osteopontin, and osteocalcin) differentiation. Terminal lineage-specific differentiation was related to differential expression of miR-17, miR-21, miR-34a, and miR-146a, decreased levels of acetylated H4 and H3K9, trimethylated H3K4 and H3K9, and the retention of H3K27me3 along with a reduction in the levels of HDAC1, DNMT1, and PRC1/2 proteins (BMI1/SUZ12). No significant distinction could be identified in the levels of expression of all epigenetic or pluripotency markers between undifferentiated MSCs isolated from AF of normal gestation and pregnancy where the fetus was damaged and between those differentiated toward adipocytes or osteoblasts. The expressional changes of those marks and microRNAs that occurred during terminal differentiation to mesodermal tissues indicate subtle epigenetic regulation in AF-MSCs when the condition of the fetus is healthy normal or diseased. More detailed studies of epigenetic mechanisms may offer a better understanding of AF-MSCs differentiation in fetus-diseased conditions and their usage in an autologous therapeutic application and prenatal disease research.

Activity of p53 in human amniotic fluid stem cells increases their potentiality as a candidate for stem cell therapy

The potential use of stem cells as a therapeutic treatment for many neurological disorders, such as stroke, has spiked an interest in their properties. Due to limitations of the present-day treatments, regenerative and protective therapies could prove very beneficial if a safe and effective treatment is identified. Using human amniotic fluid stem (hAFS) cells could theoretically provide both neuroprotective and regenerative properties to patients, and knowledge of p53's activity and function could be a key component in understanding the behavior and characteristics of these stem cells to harness their full potential. Many recent studies on p53 have provided new and valuable information that could give rise to new ideas for treatment options. More specifically, p53's activity inside hAFS cells lead them closer to becoming a potential therapeutic stem cell. Other neuroprotective treatments, such as hyperoxia and hypoxia sessions, are showing positive results. In combination, these data are helping to get closer to an effective treatment for neurological disorders.

Combination of Human Amniotic Fluid Derived-Mesenchymal Stem Cells and Nano-hydroxyapatite Scaffold Enhances Bone Regeneration

BACKGROUND:

Human amniotic fluid-derived stem cells (hAF-MSCs) have a high proliferative capacity and osteogenic differentiation potential in vitro. The combination of hAF-MSCs with three-dimensional (3D) scaffold has a promising therapeutic potential in bone tissue engineering and regenerative medicine. Selection of an appropriate scaffold material has a crucial role in a cell supporting and osteoinductivity to induce new bone formation in vivo.

AIM:

This study aimed to investigate and evaluate the osteogenic potential of the 2nd-trimester hAF-MSCs in combination with the 3D scaffold, 30% Nano-hydroxyapatite chitosan, as a therapeutic application for bone healing in the induced tibia defect in the rabbit.

SUBJECT AND METHODS:

hAF-MSCs proliferation and culture expansion was done in vitro, and osteogenic differentiation characterisation was performed by Alizarin Red staining after 14 & 28 days. Expression of the surface markers of hAF-MSCs was assessed using Flow Cytometer with the following fluorescein-labelled antibodies: CD34-PE, CD73-APC, CD90-FITC, and HLA-DR-FITC. Ten rabbits were used as an animal model with an induced defect in the tibia to evaluate the therapeutic potential of osteogenic differentiation of hAF-MSCs seeded on 3D scaffold, 30% Nano-hydroxyapatite chitosan. The osteogenic differentiated hAF-MSCs/scaffold composite system applied and fitted in the defect region and non-seeded scaffold was used as control. The histopathological investigation was performed at 2, 3, & 4 weeks post-transplantation and scanning electron microscope (SEM) was assessed at 2 & 4 weeks post-transplantation to evaluate the bone healing potential in the rabbit tibia defect.

RESULTS:

Culture and expansion of 2nd-trimester hAF-MSCs presented high proliferative and osteogenic potential in vitro. Histopathological examination for the transplanted hAF-MSCs seeded on the 3D scaffold, 30% Nano-hydroxyapatite chitosan, demonstrated new bone formation in the defect site at 2 & 3 weeks post-transplantation as compared to the control (non-seeded scaffold). Interestingly, the scaffold accelerated the osteogenic differentiation of AF-MSCs and showed complete bone healing of the defect site as compared to the control (non-seeded scaffold) at 4 weeks post-transplantation. Furthermore, the SEM analysis confirmed these findings.

CONCLUSION:

The combination of the 2nd-trimester hAF-MSCs and 3D scaffold, 30% Nano-hydroxyapatite chitosan, have a therapeutic perspective for large bone defect and could be used effectively in bone tissue engineering and regenerative medicine.

How preparation and preservation procedures affect the properties of amniotic membrane? How safe are the procedures?

Human amniotic membrane (AM) has been widely used for tissue engineering and regenerative medicine applications. AM has many favorable characteristics such as high biocompatibility, antibacterial activity, anti-scarring property, immunomodulatory effects, anti-cancer behavior and contains several growth factors that make it an excellent natural candidate for wound healing. To date, various methods have been developed to prepare, preserve, cross-link and sterilize the AM. These methods remarkably affect the morphological, physico-chemical and biological properties of AM. Optimization of an effective and safe method for preparation and preservation of AM for a specific application is critical. In this review, the isolation, different methods of preparation, preservation, cross-linking and sterilization as well as their effects on properties of AM are well discussed. For each section, at least one effective and safe protocol is described in detail.

Amniotic Fluid Cells, Stem Cells, and p53: Can We Stereotype p53 Functions?

In recent years, great interest has been devoted to finding alternative sources for human stem cells which can be easily isolated, ideally without raising ethical objections. These stem cells should furthermore have a high proliferation rate and the ability to differentiate into all three germ layers. Amniotic fluid, ordinarily discarded as medical waste, is potentially such a novel source of stem cells, and these amniotic fluid derived stem cells are currently gaining a lot of attention. However, further information will be required about the properties of these cells before they can be used for therapeutic purposes. For example, the risk of tumor formation after cell transplantation needs to be explored. The tumor suppressor protein p53, well known for its activity in controlling Cell Prolif.eration and cell death in differentiated cells, has more recently been found to be also active in amniotic fluid stem cells. In this review, we summarize the major findings about human amniotic fluid stem cells since their discovery, followed by a brief overview of the important role played by p53 in embryonic and adult stem cells. In addition, we explore what is known about p53 in amniotic fluid stem cells to date, and emphasize the need to investigate its role, particularly in the context of cell tumorigenicity.

Human platelet lysate as an alternative to fetal bovine serum for culture and endothelial differentiation of human amniotic fluid mesenchymal stem cells

Human amniotic fluid (hAF) mesenchymal stem cells (MSCs) are commonly cultured in medium containing FBS. However, there are concerns about using animal serum in therapeutic applications due to the potential for immunogenic reactions and the risk of transmission of pathogens. For safety reasons, human platelet lysate (hPL) has been suggested as a replacement for FBS because it appears to be a natural source of growth factors. In this present study, it was investigated whether FBS could be substituted with hPL in hAF-MSCs culture without affecting their properties. Pooled hPL was generated by the freeze-thaw method. The concentration of hPL was selected after evaluation by MTT assay. The hAF-MSCs were cultured in FBS- or hPL-supplemented conditions and shared a fibroblast-like morphology. Cell proliferation assays showed that the growth characteristic of hAF-MSCs cultured in 10% hPL-supplemented media was similar to those cultured in 10% FBS-supplemented media. The expression of MSC markers did not differ between the cells cultured in the different conditions. The endothelial differentiation potential was also investigated. Reverse transcription-quantitative (RT-q)PCR revealed that induced cells supplemented with hPL showed an increase level of endothelial specific gene expression compared to the FBS-supplemented cells. Immunofluorescence analysis showed specific protein localization in both induced cell groups. Additionally, induced cells supplemented with hPL had the potential to form networks on Matrigel. This present study indicated that hPL could be used to culture and enhance the endothelial differentiation potential of hAF-MSCs.

Osteogenic Differentiation Potential of Human Bone Marrow and Amniotic Fluid-Derived Mesenchymal Stem Cells in Vitro & in Vivo

BACKGROUND

Cell therapies offer a promising potential in promoting bone regeneration. Stem cell therapy presents attractive care modality in treating degenerative conditions or tissue injuries. The rationale behind this is both the expansion potential of stem cells into a large cell population size and its differentiation abilities into a wide variety of tissue types, when given the proper stimuli. A progenitor stem cell is a promising source of cell therapy in regenerative medicine and bone tissue engineering.

AIM

This study aimed to compare the osteogenic differentiation and regenerative potentials of human mesenchymal stem cells derived from human bone marrow (hBM-MSCs) or amniotic fluid (hAF-MSCs), both in vitro and in vivo studies.

SUBJECTS AND METHODS

Human MSCs, used in this study, were successfully isolated from two human sources; the bone marrow (BM) and amniotic fluid (AF) collected at the gestational ages of second or third trimesters.

RESULTS

The stem cells derived from amniotic fluid seemed to be the most promising type of progenitor cells for clinical applications. In a pre-clinical experiment, attempting to explore the therapeutic application of MSCs in bone regeneration, Rat lumbar spines defects were surgically created and treated with undifferentiated and osteogenically differentiated MSCs, derived from BM and second trimester AF. Cells were loaded on gel-foam scaffolds, inserted and fixed in the area of the surgical defect. X-Ray radiography follows up, and histopathological analysis was done three-four months post- operation. The transplantation of AF-MSCs or BM-MSCs into induced bony defects showed promising results. The AF-MSCs are offering a better healing effect increasing the likelihood of achieving successful spinal fusion. Some bone changes were observed in rats transplanted with osteoblasts differentiated cells but not in rats transplanted with undifferentiated MSCs. Longer observational periods are required to evaluate a true bone formation. The findings of this study suggested that the different sources; hBM-MSCs or hAF-MSCs exhibited remarkably different signature regarding the cell morphology, proliferation capacity and osteogenic differentiation potential.

CONCLUSIONS

AF-MSCs have a better performance in vivo bone healing than that of BM-MSCs. Hence, AF derived MSCs is highly recommended as an alternative source to BM-MSCs in bone regeneration and spine fusion surgeries. Moreover, the usage of gel-foam as a scaffold proved as an efficient cell carrier that showed bio-compatibility with cells, bio-degradability and osteoinductivity in vivo.

Smooth muscle cell differentiation from rabbit amniotic cells

Amniotic fluid (AF) is the liquid layer that provides mechanical support and allows movement of the fetus during embryogenesis. Mesenchymal stem cells (MSCs), which have differentiation capacity, are also found in AF-derived cells at a low ratio. Smooth muscle cells (SMCs) play an important role in organ function and are frequently used in tissue engineering. We examined the differentiation of AF-derived MSCs (AMSCs) into SMCs. AMSCs were sorted from cultured amniotic cells and differentiated into SMCs using differentiation agents, including platelet-derived growth factor BB (PDGF-BB) and tumor growth factor β (TGF-β). Characterization of differentiated SMCs was confirmed morphologically, molecularly (via quantitative polymerase chain reaction [qPCR] and immunocytochemistry [ICC]), and functionally (using a contractile assay and fluo-4 calcium signaling assay). Poly(lactide-co-glycolide) (PLGA) scaffolds were fabricated, and the attachment capacity of AMSCs was assessed via scanning electron microscopy. AMSCs were successfully differentiated into SMCs. Our results indicate that AMSCs change their morphology and exhibit increased expression of ACTA2 and MYH11, which was confirmed via qPCR and ICC. Furthermore, functional experiments revealed that differentiated SMCs had both contraction ability and increased Ca² concentration in the cytoplasm. Finally, PLGA scaffolds were prepared and AMSCs were successfully planted onto the scaffolds. The AMSCs fully differentiated into functional SMCs, and the PLGA polymer is a suitable scaffold material for AMSCs. With further clinical trials, AF-derived MSC-based SMC engineering may become a highly efficient treatment option.

p53 Is Active in Human Amniotic Fluid Stem Cells

Despite increasing interest in human amniotic fluid cells, very little is known about the regulation and function of p53 in this cell type. In this study, we show that undifferentiated human amniotic fluid cells express p53, yet at lower levels than in cancer cells. The p53 protein in amniotic fluid cells is mainly localized in the nuclei, however, its antiproliferative activity is compromised in these cells. Igf2, a maternal imprinted gene, and c-jun, a proto-oncogene, are regulated by p53 in these cells. DNA damage leads to an increase in p53 abundance in human amniotic fluid cells and to transcriptional activation of its target genes. Interestingly, cell differentiation toward the neural lineage leads to p53 induction as differentiation progresses.

Amniotic Fluid Stem Cells for the Treatment of Surgical Disorders in the Fetus and Neonate

Over the past decade, amniotic fluid‐derived stem cells have emerged as a novel experimental approach aimed at improving outcomes in children with congenital anomalies, including spina bifida, heart defects, and diaphragmatic hernia. Interest in these cells for the treatment of prenatally diagnosed diseases has arisen based on numerous studies demonstrating the relative ease of harvesting an abundant quantity of amniocytes from a small aliquot of fluid, the unique properties of amniocytes themselves, and the beneficial effects of amniotic fluid‐derived stem cells in experimental animal models. This report gives a brief overview of the rationale and current status of amniotic fluid stem cell‐based therapies, focusing on its relevance to birth defects affecting the fetus and neonate. The author proposes a roadmap for further study that would be required prior to clinical application of amniotic fluid stem cell technologies. stem cells translational medicine2018;7:767–773

S1P promotes migration, differentiation and immune regulatory activity in amniotic-fluid-derived stem cells

Stem cells have high potential for cell therapy in regenerative medicine. We previously isolated stem cell types from human amniotic fluid, derived from prenatal amniocentesis. One type, characterized by a fast doubling time, was designated as fast human amniotic stem cells (fHASCs). These cells exhibited high differentiation potential and immunoregulatory properties. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite that influences stem-cell pluripotency, differentiation, mobility, and regulates immune functions. In this study, we investigated the influence of S1P on fHASC migration, proliferation, differentiation and immune regulatory functions. We found that fHASC stimulation with S1P potentiated their migratory and proliferative activity in vitro. Notably, short fHASC exposure to S1P enhanced their differentiation towards multiple lineages, including adipocytes, osteocytes and endothelial cells, an effect that was associated with downregulation of the main transcription factors involved in the maintenance of a stem-cell undifferentiated state. A specific crosstalk between S1P and tumor growth factor β1 (TGF-β1) has recently been demonstrated. We found that fHASC exposure to S1P in combination with TGF-β1 promoted the expression of the immune regulatory pathway of indoleamine 2,3-dioxygenase 1 (IDO1). In addition, human peripheral blood mononuclear cells, co-cultured with fHASCs treated with S1P and TGF-β1, expanded regulatory T-cells, via a mechanism requiring IDO1. Overall, this study demonstrates that S1P potentiates several properties in fHASCs, an effect that may be critical for exploiting the therapeutic potential of fHASCs and might explain the specific effects of S1P on stem cells during pregnancy.

Biological characterization and pluripotent identification of ovine amniotic fluid stem cells

Mesenchymal stem cells derived from amniotic fluid have become one of the most potential stem cell source for cell-based therapy for the reason they can be harvested at low cost and without ethical problems. Here, we obtained amniotic fluid stem cells (AFSCs) from ovine amniotic fluid and studied the expansion capacity, cell markers expression, karyotype, and multilineage differentiation ability. In our work, AFSCs were subcultured to passage 62. The cell markers, CD29, CD44, CD73 and OCT4 which analyzed by RT-PCR were positive; CD44, CD73, CD90, CD105, NANOG, OCT4 analyzed by immunofluorescence and flow cytometry were also positive. The growth curves of different passages were all typically sigmoidal. The different passages cells took on a normal karyotype. In addition, AFSCs were successfully induced to differentiate into adipocytes, osteoblasts and chondrocytes. The results suggested that the AFSCs isolated from ovine maintained normal biological characteristics and their multilineage differentiation potential provides many potential applications in cell-based therapies and tissue engineering.

The effect of meconium exposure on the expression and differentiation of amniotic fluid mesenchymal stem cells

BACKGROUND:

The goal of this study was to determine if exposure to meconium would alter the phenotype of amniotic fluid mesenchymal stem cells (AF-MSCs) and the ability of these cells to be differentiated into distal airway type cells.

METHODS:

Meconium was collected, lyophilized and resuspended in PBS at 3 different concentrations (high, medium, and low). AF-MSCs were cultured in the presence of this meconium suspension for 8 hours and then analyzed for changes in gene expression. Additionally, AF-MSCs exposed to meconium were differentiated for 14 days using modified small airway growth medium (mSAGM) and gene expression was determined. As a spontaneous differentiation control, meconium exposed AF-MSCs were cultured in amniotic fluid stem cell medium (AF medium).

RESULTS:

After 8 hours of exposure in culture, AF-MSCs had increased expression of distal airway genes aquaporin 5 (AQP5) and surfactant protein c (SPC) when cultured in AF medium containing meconium. These gene expression levels were similar to that of AF-MSCs that were differentiated in mSAGM for 14 days. Furthermore, there was an up regulation of pluripotency genes NANOG and OCT4 in response to low meconium concentration for 8 hours. Following 14 days of culture in mSAGM, there was an upregulation of TTF1, SPC and AQP5 expression in the control, as well as in the low and medium meconium exposed groups indicating that these cells were still able to be differentiated. High meconium concentration did, however, appear to influence the level of distal airway gene expression after 14 days in mSAGM. After 14 days in AF medium, there was significant downregulation in pluripotency and mesenchymal markers as well as distal airway gene expression in all groups.

CONCLUSION:

The phenotype of AF-MSCs is modulated by meconium exposure; however, the cells were still able to differentiate into distal airway gene and protein expression. This result supports the hypothesis that progenitor cells exist in the amniotic fluid and the presence of meconium may affect their initial phenotype. However, these cells were still able to be differentiated to a distal lung phenotype.

Menaquinone-4 enhances osteogenic potential of human amniotic fluid mesenchymal stem cells cultured in 2D and 3D dynamic culture systems

Menaquinones, also known as Vitamin K2 family, regulate calcium homeostasis in a 'bone-vascular cross-talk' and recently received particular attention for their positive effect on bone formation. Given that the correlation between menaquinones and bone metabolism to date is still unclear, the objective of our study was to investigate the possible role of menaquinone-4 (MK-4), an isoform of the menaquinones family, in the modulation of osteogenesis. For this reason, we used a model of human amniotic fluid mesenchymal stem cells (hAFMSCs) cultured both in two-dimensional (2D) and three-dimensional (3D; RCCS™bioreactor) in vitro culture systems. Furthermore, to mimic the 'bone remodelling unit' in vitro, hAFMSCs were co-cultured in the 3D system with human monocyte cells (hMCs) as osteoclast precursors. The results showed that in a conventional 2D culture system, hAFMSCs were responsive to the MK-4, which significantly improved the osteogenic process through γ-glutamyl carboxylase-dependent pathway. The same results were obtained in the 3D dynamic system where MK-4 treatment supported the osteoblast-like formation promoting the extracellular bone matrix deposition and the expression of the osteogenic-related proteins (alkaline phosphatase, osteopontin, collagen type-1 and osteocalcin). Notably, when the hAFMSCs were co-cultured in a 3D dynamic system with the hMCs, the presence of MK-4 supported the cellular aggregate formation as well as the osteogenic function of hAFMSCs, but negatively affected the osteoclastogenic process. Taken together, our results demonstrate that MK-4 supported the aggregate formation of hAFMSCs and increased the osteogenic functions. Specifically, our data could help to optimize bone regenerative medicine combining cell-based approaches with MK-4 treatment.

Amniotic Fluid Stem Cells: A New Era in Regenerative Medicine

Regenerative medicine has become an emerging field which focuses on repair, replacement or regeneration of cells, tissues and the entire organs. The regeneration may occur in patient's own body by using their system as a bioreactor, e.g., cell therapy that involves transplantation of stem cells capable of proliferating, differentiating and replacing damaged host cells. As the field of regenerative medicine advances, and sources of stem cells has been intensified. Though embryonic and adult tissues can be used for isolation of pluripotent stem cells, the amniotic fluid (AF) has been proposed as an alternative source of stem cells for tissue regeneration. AF cells could be banked and used for either allogeneic or autologous transplantation.

Amniotic fluid as a source of engraftable stem cells

The ability of stem cells to differentiate into various lineages has made them powerful tools of regenerative medicine and applicable to multiple human diseases. Of particular interest, amniotic fluid-derived stem cells (AFSC) have been characterized to express both adult and embryonic cell markers, indicating them as cells within an intermediate stage between embryonic and adult phenotype. AFSC can differentiate into cells of all three germ layers, including hepatic, myogenic, osteogenic, and neurogenic cell types. Furthermore, AFSC have minimal replicative senescence, retaining the ability to divide effectively for over 250 doublings. These facts indicate that amniotic fluid may exist as a promising donor source of stem cells for the treatment of multiple clinically relevant conditions. Of particular interest is the convenience of harvesting stem cells from the amniotic fluid stem for the treatment of newborns, as well as for banking or cryopreserving purposes to be used at a later date. Importantly, the promise of amniotic fluid as a source of stem cells merits ongoing research into their potential therapeutic applications. This paper is a review article. Referred literature in this paper has been listed in the references section. The datasets supporting the conclusions of this article are available online by searching various databases, including PubMed. Some original points in this article come from the laboratory practice in our research center and the authors' experiences.

Glycogen synthase kinase 3 (GSK3)-inhibitor SB216763 promotes the conversion of human umbilical cord mesenchymal stem cells into neural precursors in adherent culture

The ability to generate neural progenitor cells from human umbilical cord mesenchymal stem cells (hUC-MSCs) has provided an option to treat neurodegenerative diseases. To establish a method for this purpose, we characterized the early neural markers of hUC-MSCs-derived cells under different conditions. We found that neither the elimination of signals for alternative fate nor N2 supplement was sufficient to differentiate hUC-MSCs into neural precursor cells, but the GSK3 inhibitor SB216763 could promote an efficient neural commitment of hUC-MSCs. The results indicated that Wnt/β-catenin might play an important role during the early neural differentiation of hUC-MSCs. Here, we report a method for hUC-MSCs to commit efficiently into a neural fate within a short period of time. This protocol provides an efficient method for hUC-MSCs-based neural regeneration.

Differentiation of Enhanced Green Fluorescent Protein-Labeled Mouse Amniotic Fluid-Derived Stem Cells into Cardiomyocyte-Like Beating Cells

BACKGROUND

Amniotic fluid-derived stem cells (AFSCs) possess optimal differentiation potential and are a promising resource for cell therapy and tissue engineering. Mouse is a good model to be studied for pre-clinical research.

METHODS

In this study, we successfully established enhanced green fluorescent protein mouse-derived amniotic fluid stem cells (EGFP-mAFSCs) and investigated whether EGFP-mAFSCs possess the ability to differentiate into cardiomyocytes by in vitro culture. We evaluated stem-cell differentiation using immunofluorescence.

RESULTS

This study showed that EGFP-mAFSCs can give rise to spontaneously beating cardiomyocyte-like cells expressing the specific markers c-kit, myosin heavy chain, and cardiac troponin I.

CONCLUSIONS

We demonstrated that mAFSCs have the in vitro propensity to acquire a cardiomyogenic phenotype and to a certain extent cardiomyocytes; however the process efficiency which gives rise to cardiomyocyte-like cells remains quite low (2 out of 10 were found).

KEY WORDS

Amniotic fluid; Cardiomyocytes; In vitro differentiation; Stem cells.

The Modulatory Effects of Mesenchymal Stem Cells on Osteoclastogenesis

The effect of mesenchymal stem cells (MSCs) on bone formation has been extensively demonstrated through several in vitro and in vivo studies. However, few studies addressed the effect of MSCs on osteoclastogenesis and bone resorption. Under physiological conditions, MSCs support osteoclastogenesis through producing the main osteoclastogenic cytokines, RANKL and M-CSF. However, during inflammation, MSCs suppress osteoclast formation and activity, partly via secretion of the key anti-osteoclastogenic factor, osteoprotegerin (OPG). In vitro, co-culture of MSCs with osteoclasts in the presence of high concentrations of osteoclast-inducing factors might reflect the in vivo inflammatory pathology and prompt MSCs to exert an osteoclastogenic suppressive effect. MSCs thus seem to have a dual effect, by stimulating or inhibiting osteoclastogenesis, depending on the inflammatory milieu. This effect of MSCs on osteoclast formation seems to mirror the effect of MSCs on other immune cells, and may be exploited for the therapeutic potential of MSCs in bone loss associated inflammatory diseases.

A Mini Overview of Isolation, Characterization and Application of Amniotic Fluid Stem Cells

Amniotic fluid represents rich sources of stem cells that can be used in treatments for a wide range of diseases. Amniotic fluid- stem cells have properties intermediate between embryonic and adult mesenchymal stem cells which make them particularly attractive for cellular regeneration and tissue engineering. Furthermore, scientists are interested in these cells because they come from the amniotic fluid that is routinely discarded after birth. In this review we give a brief introduction of amniotic fluid followed by a description of the cells present within this fluid and aim to summarize the all existing isolation methods, culturing, characterization and application of these cells. Finally, we elaborate on the differentiation and potential for these cells to promote regeneration of various tissue defects, including fetal tissue, the nervous system, heart, lungs, kidneys, bones, and cartilage in the form of table.

Re-epithelialization: a key element in tracheal tissue engineering

Trachea-tissue engineering is a thriving new field in regenerative medicine that is reaching maturity and yielding numerous promising results. In view of the crucial role that the epithelium plays in the trachea, re-epithelialization of tracheal substitutes has gradually emerged as the focus of studies in tissue-engineered trachea. Recent progress in our understanding of stem cell biology, growth factor interactions and transplantation immunobiology offer the prospect of optimization of a tissue-engineered tracheal epithelium. In addition, advances in cell culture technology and successful applications of clinical transplantation are opening up new avenues for the construction of a tissue-engineered tracheal epithelium. Therefore, this review summarizes current advances, unresolved obstacles and future directions in the reconstruction of a tissue-engineered tracheal epithelium.

Stem cells from amniotic fluid--Potential for regenerative medicine

Regenerative medicine has recently been established as an emerging field focussing on repair, replacement or regeneration of cells, tissues and whole organs. The significant recent advances in the field have intensified the search for novel sources of stem cells with potential for therapy. Recently, researchers have identified the amniotic fluid as an untapped source of stem cells that are multipotent, possess immunomodulatory properties and do not have the ethical and legal limitations of embryonic stem cells. Stem cells from the amniotic fluid have been shown to differentiate into cell lineages representing all three embryonic germ layers without generating tumours, which make them an ideal candidate for tissue engineering applications. In addition, their ability to engraft in injured organs and modulate immune and repair responses of host tissues suggest that transplantation of such cells may be useful for the treatment of various degenerative and inflammatory diseases affecting major tissues/organs. This review summarises the evidence on amniotic fluid cells over the past 15 years and explores the potential therapeutic applications of amniotic fluid stem cells and amniotic fluid mesenchymal stem cells.

Stem cells from human amniotic fluid exert immunoregulatory function via secreted indoleamine 2,3-dioxygenase1

Although human amniotic fluid does contain different populations of foetal-derived stem cells, scanty information is available on the stemness and the potential immunomodulatory activity of in vitro expanded, amniotic fluid stem cells. By means of a methodology unrequiring immune selection, we isolated and characterized different stem cell types from second-trimester human amniotic fluid samples (human amniotic fluid stem cells, HASCs). Of those populations, one was characterized by a fast doubling time, and cells were thus designated as fHASCs. Cells maintained their original phenotype under prolonged in vitro passaging, and they were able to originate embryoid bodies. Moreover, fHASCs exhibited regulatory properties when treated with interferon (IFN)-γ, including induction of the immunomodulatory enzyme indoleamine 2,3-dioxygenase 1 (IDO1). On coculture with human peripheral blood mononuclear cells, IFN-γ-treated fHASCs caused significantly decreased T-cell proliferation and increased frequency in CD4(+)  CD25(+)  FOXP3(+) regulatory T cells. Both effects required an intact IDO1 function and were cell contact-independent. An unprecedented finding in our study was that purified vesicles from IFN-γ-treated fHASCs abundantly expressed the functional IDO1 protein, and those vesicles were endowed with an fHASC-like regulatory function. In vivo, fHASCs were capable of immunoregulatory function, promoting allograft survival in a mouse model of allogeneic skin transplantation. This was concurrent with the expansion of CD4(+)  CD25(+)  Foxp3(+) T cells in graft-draining lymph nodes from recipient mice. Thus fHASCs, or vesicles thereof, may represent a novel opportunity for immunoregulatory maneuvers both in vitro and in vivo.

Osteogenic differentiation of amniotic fluid mesenchymal stromal cells and their bone regeneration potential

In orthopedics, tissue engineering approach using stem cells is a valid line of treatment for patients with bone defects. In this context, mesenchymal stromal cells of various origins have been extensively studied and continue to be a matter of debate. Although mesenchymal stromal cells from bone marrow are already clinically applied, recent evidence suggests that one may use mesenchymal stromal cells from extra-embryonic tissues, such as amniotic fluid, as an innovative and advantageous resource for bone regeneration. The use of cells from amniotic fluid does not raise ethical problems and provides a sufficient number of cells without invasive procedures. Furthermore, they do not develop into teratomas when transplanted, a consequence observed with pluripotent stem cells. In addition, their multipotent differentiation ability, low immunogenicity, and anti-inflammatory properties make them ideal candidates for bone regenerative medicine. We here present an overview of the features of amniotic fluid mesenchymal stromal cells and their potential in the osteogenic differentiation process. We have examined the papers actually available on this regard, with particular interest in the strategies applied to improve in vitro osteogenesis. Importantly, a detailed understanding of the behavior of amniotic fluid mesenchymal stromal cells and their osteogenic ability is desirable considering a feasible application in bone regenerative medicine.

Comparative proteomic analysis of two distinct stem-cell populations from human amniotic fluid

Human amniotic fluid (AF) contains a variety of stem cells of embryonic and extra-embryonic origins. We characterized two distinct types of stem cells isolated from residual AF material derived from prenatal diagnostic amniocentesis. The two types of cells differed in their morphology and growth kinetics, showing fast (fast human amniotic stem cells; fHASCs) or slow (slow human amniotic stem cells; sHASCs) population-doubling times. Both fHASCs and sHASCs expressed pluripotent stem-cell markers, yet unlike sHASCs, clonogenic fHASCs would generate embryoid bodies and maintain their original phenotype during prolonged in vitro passaging. fHASCs - but not sHASCs - expressed the KLF4, SSEA-4 and CD117 markers. Differential proteomic analysis allowed us to identify the protein patterns specific for either cell type as potentially contributing to their distinct phenotypes. We found thirty-six proteins that were differentially expressed by the two cell types, and those proteins were classified according to their biological and molecular functions. Bioinformatic cluster analysis revealed differential occurrence of cytoskeletal proteins, such as vimentin, F-actin-binding protein, and chloride intracellular channel protein 1. Selected proteins differentially expressed by fHASCs and sHASCs were further characterized by Western blot analysis and confocal microscopy.

Gene delivery in tissue engineering and regenerative medicine

As a promising strategy to aid or replace tissue/organ transplantation, gene delivery has been used for regenerative medicine applications to create or restore normal function at the cell and tissue levels. Gene delivery has been successfully performed ex vivo and in vivo in these applications. Excellent proliferation capabilities and differentiation potentials render certain cells as excellent candidates for ex vivo gene delivery for regenerative medicine applications, which is why multipotent and pluripotent cells have been intensely studied in this vein. In this review, gene delivery is discussed in detail, along with its applications to tissue engineering and regenerative medicine. A definition of a stem cell is compared to a definition of a stem property, and both provide the foundation for an in-depth look at gene delivery investigations from a germ lineage angle.