Characterization and potential applications of progenitor-like cells isolated from horse amniotic membrane

Stem-Cell-Driven Chondrogenesis: Perspectives on Amnion-Derived Cells

Regenerative medicine harnesses stem cells' capacity to restore damaged tissues and organs. In vitro methods employing specific bioactive molecules, such as growth factors, bio-inductive scaffolds, 3D cultures, co-cultures, and mechanical stimuli, steer stem cells toward the desired differentiation pathways, mimicking their natural development. Chondrogenesis presents a challenge for regenerative medicine. This intricate process involves precise modulation of chondro-related transcription factors and pathways, critical for generating cartilage. Cartilage damage disrupts this process, impeding proper tissue healing due to its unique mechanical and anatomical characteristics. Consequently, the resultant tissue often forms fibrocartilage, which lacks adequate mechanical properties, posing a significant hurdle for effective regeneration. This review comprehensively explores studies showcasing the potential of amniotic mesenchymal stem cells (AMSCs) and amniotic epithelial cells (AECs) in chondrogenic differentiation. These cells exhibit innate characteristics that position them as promising candidates for regenerative medicine. Their capacity to differentiate toward chondrocytes offers a pathway for developing effective regenerative protocols. Understanding and leveraging the innate properties of AMSCs and AECs hold promise in addressing the challenges associated with cartilage repair, potentially offering superior outcomes in tissue regeneration.

Amniotic Mesenchymal-Derived Extracellular Vesicles and Their Role in the Prevention of Persistent Post-Breeding Induced Endometritis

Persistent post-breeding induced endometritis (PPBIE) is considered a major cause of subfertility in mares. It consists of persistent or delayed uterine inflammation in susceptible mares. There are many options for the treatment of PPBIE, but in this study, a novel approach aimed at preventing the onset of PPBIE was investigated. Stallion semen was supplemented with extracellular vesicles derived from amniotic mesenchymal stromal cells (AMSC-EVs) at the time of insemination to prevent or limit the development of PPBIE. Before use in mares, a dose–response curve was produced to evaluate the effect of AMSC-EVs on spermatozoa, and an optimal concentration of 400 × 106 EVs with 10 × 106 spermatozoa/mL was identified. At this concentration, sperm mobility parameters were not negatively affected. Sixteen susceptible mares were enrolled and inseminated with semen (n = 8; control group) or with semen supplemented with EVs (n = 8; EV group). The supplementation of AMSC-EVs to semen resulted in a reduction in polymorphonuclear neutrophil (PMN) infiltration as well as intrauterine fluid accumulation (IUF; p < 0.05). There was a significant reduction in intrauterine cytokine levels (p < 0.05) for TNF-α and IL-6 and an increase in anti-inflammatory IL-10 in mares in the EV group, suggesting successful modulation of the post-insemination inflammatory response. This procedure may be useful for mares susceptible to PPBIE.

Hypoxia-Mimetic CoCl2 Agent Enhances Pro-Angiogenic Activities in Ovine Amniotic Epithelial Cells-Derived Conditioned Medium

Amniotic epithelial stem cells (AECs) are largely studied for their pro-regenerative properties. However, it remains undetermined if low oxygen (O₂) levels that AECs experience in vivo can be of value in maintaining their biological properties after isolation. To this aim, the present study has been designed to evaluate the effects of a hypoxia-mimetic agent, cobalt chloride (CoCl₂), on AECs’ stemness and angiogenic activities. First, a CoCl₂ dose-effect was performed to select the concentration able to induce hypoxia, through HIF-1α stabilization, without promoting any cytotoxicity effect assessed through the analysis of cell vitality, proliferation, and apoptotic-related events. Then, the identified CoCl₂ dose was evaluated on the expression and angiogenic properties of AECs’ stemness markers (OCT-4, NANOG, SOX-2) by analysing VEGF expression, angiogenic chemokines’ profiles, and AEC-derived conditioned media activity through an in vitro angiogenic xeno-assay. Results demonstrated that AECs are sensitive to the cytotoxicity effects of CoCl₂. The unique concentration leading to HIF-1α stabilization and nuclear translocation was 10 µM, preserving cell viability and proliferation up to 48 h. CoCl₂ exposure did not modulate stemness markers in AECs while progressively decreasing VEGF expression. On the contrary, CoCl₂ treatment promoted a significant short-term release of angiogenic chemokines in culture media (CM). The enrichment in bio-active factors was confirmed by the ability of CoCl₂-derived CM to induce HUVEC growth and the cells’ organization in tubule-like structures. These findings demonstrate that an appropriate dose of CoCl₂ can be adopted as a hypoxia-mimetic agent in AECs. The short-term, chemical-induced hypoxic condition can be targeted to enhance AECs’ pro-angiogenic properties by providing a novel approach for stem cell-free therapy protocols.

Application of Perinatal Derivatives in Ovarian Diseases

Reproductive diseases could lead to infertility and have implications for overall health, most importantly due to psychological, medical and socio-economic consequences for individuals and society. Furthermore, economical losses also occur in animal husbandry. In both human and veterinary medicine, hormonal and surgical treatments, as well as assisted reproductive technologies are used to cure reproductive disorders, however they do not improve fertility. With ovarian disorders being the main reproductive pathology in human and bovine, over the past 2 decades research has approached regenerative medicine in animal model to restore normal function. Ovarian pathologies are characterized by granulosa cell and oocyte apoptosis, follicular atresia, decrease in oocyte quality and embryonic development potential, oxidative stress and mitochondrial abnormalities, ultimately leading to a decrease in fertility. At current, application of mesenchymal stromal cells or derivatives thereof represents a valid strategy for regenerative purposes. Considering their paracrine/autocrine mode of actions that are able to regenerate injured tissues, trophic support, preventing apoptosis and fibrosis, promoting angiogenesis, stimulating the function and differentiation of endogenous stem cells and even reducing the immune response, are all important players in their future therapeutic success. Nevertheless, obtaining mesenchymal stromal cells (MSC) from adult tissues requires invasive procedures and implicates decreased cell proliferation and a reduced differentiation capacity with age. Alternatively, the use of embryonic stem cells as source of cellular therapeutic encountered several ethical concerns, as well as the risk of teratoma formation. Therefore, several studies have recently focussed on perinatal derivatives (PnD) that can be collected non-invasively and, most importantly, display similar characteristics in terms of regenerating-inducing properties, immune-modulating properties and hypo-immunogenicity. This review will provide an overview of the current knowledge and future perspectives of PnD application in the treatment of ovarian hypofunction.

Morphological study of equine amniotic compartment

Exfoliative cytology of human amniotic fluid (AF) has been extensively studied since 1940s, but no data exist in equine species. The AF compartment represents the environment in which the foetus grows and matures, and its composition changes, reflecting foetal well-being and development. The aim of this study was to describe for the first time the morphology of equine AF cells and amniotic membrane (AM) with light microscopy (LM) and transmission electron microscopy (TEM). AF was collected at parturition within 5 min after the appearance of the AM with a 60 mL syringe from 34 mares and samples of AM were collected from a subset of 7 mares with normal pregnancy hospitalized for attended parturition. For LM observation, a sample of cytocentrifuged fresh AF was stained with May-Grünwald Giemsa and AM sections were stained with H-E. For TEM observation, AF and AM were fixed, embedded in epoxy resins, then sectioned and stained with uranyl acetate and lead citrate solutions. Nucleated and anucleated squamous cells with basophilic cytoplasm, intensely basophilic cornified cells, polymorphonuclear cells, and clusters of eosinophilic amorphous substance were observed. Cells presumably derived from tracheal epithelium and small round nucleated cells with eosinophilic cytoplasm presumably derived from amniotic or urinary epithelium were occasionally found. Lamellar body-like structures (LBs) were present in some epithelial cells. In AM, epithelial, basal and mesenchymal layers were clearly visible with both techniques as previously described. Epithelial cells had several cytoplasmic vacuolization and microvilli were present on apical surface. The connective tissue presented fibroblasts, mesenchymal and rare polymorphonuclear cells, surrounded by abundant extracellular matrix, with distribution of collagen fibres. This is the first report about equine amniotic compartment description by LM and TEM. As recently reported in human medicine, the AM could be a second potential source of pulmonary surfactant, given the finding of LBs inside the cells which could have the same function as in humans. Further studies in samples collected at different gestational ages could increase the knowledge of AF cells and their modification during pregnancy, as well as a better comprehension of the role of AM as a secondary source of pulmonary surfactant in the horse. The diagnostic evaluation of AF cellular composition in high-risk pregnancies may also be investigated.

Treatment of Chronic Spinal Cord Injury in Dogs Using Amniotic Membrane-Derived Stem Cells: Preliminary Results

Introduction

Intervertebral disc diseases (IVDD) represent the majority of neurological attendance and responsible for the most cases of paralysis in dogs. Treatments currently used do not show satisfactory results in patients with more severe and chronic neurological manifestations.

Methods

To promote nerve and muscular recovery, as well as improve quality of life, we aimed to create a double-blind test method, associating spinal decompression surgery and allogeneic transplantation of amniotic membrane-derived stem cells (AMSCs) in dogs with chronic IVDD. Cells were characterized as fetal mesenchymal cells and safe for application. Eight animals completed the experiment: stem cell applications were made in four animals that had previously undergone an unsuccessful surgical procedure (“SC group”, n = 4); two animals were submitted to surgery, followed by applications of stem cells (“Surgery + SC”, n = 2); two other animals were submitted to surgery, followed by the application of saline solution (“Surgery + placebo”, n = 2). During the surgical procedure, a topical application was performed on the lesion and after fifteen and forty-five days another two applications were made via epidural. Animals were monitored biweekly and reassessed three months after surgery, by functional tests and magnetic resonance exams.

Results

Some animals presented significant neurological improvement, such as the recovery of nociception and ability to remain on station. Despite the need further studies, until the present moment, cell therapy has been feasible and has no harmful effects on animals.

Conclusion

The protocol of preclinical trial showed the association with decompressive surgery and cell transplantation in dogs with thoracolumbar IVDD proved feasible, and it was possible to observe neurological improvement after treatment. No tissue improvement through MRI was found. The double-blind test guaranteed reliability of the evaluations and results obtained that, even with a small sample size, generated satisfactory results for the animals and owners.

Therapeutic mesenchymal stromal stem cells: Isolation, characterization and role in equine regenerative medicine and metabolic disorders

Mesenchymal stromal cells (MSC) have become a popular treatment modality in equine orthopaedics. Regenerative therapies are especially interesting for pathologies like complicated tendinopathies of the distal limb, osteoarthritis, osteochondritis dissecans (OCD) and more recently metabolic disorders. Main sources for MSC harvesting in the horse are bone marrow, adipose tissue and umbilical cord blood. While the acquisition of umbilical cord blood is fairly easy and non-invasive, extraction of bone marrow and adipose tissue requires more invasive techniques. Characterization of the stem cells as a result of any isolation method, is also a crucial step for the confirmation of the cells' stemness properties; thus, three main characteristics must be fulfilled by these cells, namely: adherence, expression of a series of well-defined differentiation clusters as well as pluripotency. EVs, resulting from the paracrine action of MSCs, also play a key role in the therapeutic mechanisms mediated by stem cells; MSC-EVs are thus largely implicated in the regulation of proliferation, maturation, polarization and migration of various target cells. Evidence that EVs alone represent a complex network 0involving different soluble factors and could then reflect biophysical characteristics of parent cells has fuelled the importance of developing highly specific techniques for their isolation and analysis. All these aspects related to the functional and technical understanding of MSCs will be discussed and summarized in this review.

Differentiation Potential of Mesenchymal Stem/Stromal Cells Is Altered by Intrauterine Growth Restriction

Consistency in clinical outcomes is key to the success of therapeutic Mesenchymal Stem/Stromal cells (MSCs) in regenerative medicine. MSCs are used to treat both humans and companion animals (horses, dogs, and cats). The properties of MSC preparations can vary significantly with factors including tissue of origin, donor age or health status. We studied the effects of developmental programming associated with intrauterine growth restriction (IUGR) on MSC properties, particularly related to multipotency. IUGR results from inadequate uterine capacity and placental insufficiency of multifactorial origin. Both companion animals (horses, dogs, cats) and livestock (pigs, sheep, cattle) can be affected by IUGR resulting in decreased body size and other associated changes that can include, alterations in musculoskeletal development and composition, and increased adiposity. Therefore, we hypothesized that this dysregulation occurs at the level of MSCs, with the cells from IUGR animals being more prone to differentiate into adipocytes and less to other lineages such as chondrocytes and osteocytes compared to those obtained from normal animals. IUGR has consequences on health and performance in adult life and in the case of farm animals, on meat quality. In humans, IUGR is linked to increased risk of metabolic (type 2 diabetes) and other diseases (cardiovascular), later in life. Here, we studied porcine MSCs where IUGR occurs spontaneously, and shows features that recapitulate human IUGR. We compared the properties of adipose-derived MSCs from IUGR (IUGR-MSCs) and Normal (Normal-MSCs) new-born pig littermates. Both MSC types grew clonally and expressed typical MSC markers (CD105, CD90, CD44) at similar levels. Importantly, tri-lineage differentiation capacity was significantly altered by IUGR. IUGR-MSCs had higher adipogenic capacity than Normal-MSCs as evidenced by higher adipocyte content and expression of the adipogenic transcripts, PPARγ and FABP4 (P < 0.05). A similar trend was observed for fibrogenesis, where, upon differentiation, IUGR-MSCs expressed significantly higher levels of COL1A1 (P < 0.03) than Normal-MSCs. In contrast, chondrogenic and osteogenic potential were decreased in IUGR-MSCs as shown by a smaller chondrocyte pellet and osteocyte staining, and lower expression of SOX9 (P < 0.05) and RUNX2 (P < 0.02), respectively. In conclusion, the regenerative potential of MSCs appears to be determined prenatally in IUGR and this should be taken into account when selecting cell donors in regenerative therapy programmes both in humans and companion animals.

Human Amniotic Epithelial Stem Cells: A Promising Seed Cell for Clinical Applications

Perinatal stem cells have been regarded as an attractive and available cell source for medical research and clinical trials in recent years. Multiple stem cell types have been identified in the human placenta. Recent advances in knowledge on placental stem cells have revealed that human amniotic epithelial stem cells (hAESCs) have obvious advantages and can be used as a novel potential cell source for cellular therapy and clinical application. hAESCs are known to possess stem-cell-like plasticity, immune-privilege, and paracrine properties. In addition, non-tumorigenicity and a lack of ethical concerns are two major advantages compared with embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). All of the characteristics mentioned above and other additional advantages, including easy accessibility and a non-invasive application procedure, make hAESCs a potential ideal cell type for use in both research and regenerative medicine in the near future. This review article summarizes current knowledge on the characteristics, therapeutic potential, clinical advances and future challenges of hAESCs in detail.

Distinctive Cellular Transcriptomic Signature and MicroRNA Cargo of Extracellular Vesicles of Horse Adipose and Endometrial Mesenchymal Stem Cells from the Same Donors

Equine endometrial and adipose mesenchymal stem cells (eMSCs and aMSCs, respectively) were isolated from the same donors of thoroughbred mares. The cells displayed characteristic features of MSCs, including trilineage mesodermal and also neurogenic differentiation. We evaluated the influence of cellular origin on their transcriptome profile. Cellular RNA was isolated and sequenced and extracellular vesicles (EVs) were obtained from conditioned medium of cells cultured in medium depleted of EVs, and their microRNA (miRNA) cargo analyzed by sequencing. Differential expression of mRNAs and EV-miRNA was analyzed, as well as pathways and processes most represented in each cell origin. mRNA reads from all expressed genes clustered according to the cellular origin. A total of 125 up- and 51 downregulated genes were identified and 31 differentially expressed miRNAs. Based on mRNA sequencing, endometrial MSCs strongly upregulated genes involved in the Hippo, transforming growth factor beta, and pluripotency signaling pathways. Alongside with this, pathways involved in extracellular matrix reorganization were the most represented in the miRNA cargo of EVs secreted by eMSCs. The niche from which MSCs originated defined the transcriptomic signature of the cells, including the secretion of lineage-specific loaded EV to ensure proper communication and homeostasis. Identification and testing their biological functions can provide new tools for the therapeutic use of horse MSC.

Characterization and Immunomodulation of Canine Amniotic Membrane Stem Cells

PURPOSE

Amniotic membrane stem cells have a high capacity of proliferation, cell expansion, and plasticity, as well as immunomodulatory properties that contribute to maternal-fetal tolerance. Owing to the lack of research on human amniotic membrane at different gestational stages, the canine model is considered ideal because of its genetic and physiological similarities. We aimed to characterize the canine amniotic membrane (CAM) cell lineage in different gestational stages and evaluate the expression of immunomodulatory genes.

MATERIALS AND METHODS

Twenty CAMs from early (20-30 days) (n=7), mid- (31-45 days) (n=7), and late gestation (46-63 days) (n=6) stages were studied. The cell features were assessed by cell viability tests, growth curve, colony-forming units, in vitro differentiation, cell labeling for different immunophenotypes, and pluripotent potential markers. The cells were subjected to RT-PCR and qPCR analysis to determine the expression of IDO, HGF, EGF, PGE2, and IL-10 genes.

RESULTS

CAM cells exhibited a fibroblastoid morphology and adherence to plastic with an average cell viability of 78.5%. The growth curve indicated a growth peak in the second passage and we obtained an average of 138.2 colonies. Osteogenic, chondrogenic, and adipogenic lineages were confirmed by in vitro differentiation assays. Cellular immunophenotyping experiments confirmed the presence of positive mesenchymal markers (CD90 and CD105) and the low or negative expression of hematopoietic markers (CD45 and CD34). Qualitative analysis of the immunomodulatory functions indicated the expression of the IDO, HGF, EGF5, and PGE2 genes. When stimulated by interferon-gamma, CAM cells exhibited higher IDO levels throughout gestation.

CONCLUSION

The CAMs from different gestational stages presented features consistent with mesenchymal stem cell lineage; better results were observed during the late gestation stage. Therefore, the gestational stage is a key factor that may influence the functionality of therapies when using fetal membrane tissues from different periods of pregnancy.

Priming with inflammatory cytokines is not a prerequisite to increase immune-suppressive effects and responsiveness of equine amniotic mesenchymal stromal cells

BACKGROUND

Equine amniotic mesenchymal stromal cells (AMSCs) and their conditioned medium (CM) were evaluated for their ability to inhibit in vitro proliferation of peripheral blood mononuclear cells (PBMCs) with and without priming. Additionally, AMSC immunogenicity was assessed by expression of MHCI and MHCII and their ability to counteract the in vitro inflammatory process.

METHODS

Horse PBMC proliferation was induced with phytohemagglutinin. AMSC priming was performed with 10 ng/ml of TNF-α, 100 ng/ml of IFN-γ, and a combination of 5 ng/ml of TNF-α and 50 ng/ml of IFN-γ. The CM generated from naïve unprimed and primed AMSCs was also tested to evaluate its effects on equine endometrial cells in an in vitro inflammatory model induced by LPS. Immunogenicity marker expression (MHCI and II) was evaluated by qRT-PCR and by flow cytometry.

RESULTS

Priming does not increase MHCI and II expression. Furthermore, the inhibition of PBMC proliferation was comparable between naïve and conditioned cells, with the exception of AMSCs primed with both TNF-α and IFN-γ that had a reduced capacity to inhibit T cell proliferation. However, AMSC viability was lower after priming than under other experimental conditions. CM from naïve and primed AMSCs strongly inhibited PBMC proliferation and counteracted the inflammatory process, rescuing about 65% of endometrial cells treated by LPS.

CONCLUSION

AMSCs and their CM have a strong capacity to inhibit PBMC proliferation, and priming is not necessary to improve their immunosuppressive activity or reactivity in an inflammatory in vitro model.

Different Culture Times Affect MicroRNA Cargo in Equine Amniotic Mesenchymal Cells and Their Microvesicles

Conditioned medium (CM) and microvesicles (MVs) are produced using different protocols: CM is collected following 12-96 h of cell culture without renewal of tissue culture medium, while MVs are collected after overnight cell culture. For future comparative studies in regenerative medicine looking at the efficacy of CM and MVs, it is important to understand how the quality of cell secretions is affected by culture. The aim of this study was to evaluate whether the duration of culturing influences the micro-RNAs (miRNAs) cargo of equine amniotic mesenchymal cells (AMCs) and their MVs. The analysis identified 990 miRNAs. After one night, there were 347 differently expressed (DE)-miRNAs between MVs and cells, whereas after four nights there were 359. About 58.3% of the DE-miRNAs were shared between samples produced under the two conditions. The comparison between miRNA content in AMC cells cultured for one night versus four nights showed eight DE-Equus caballus (eca)-miRNAs, which target genes were involved in immune response to external stimulus, inflammatory response, and production of reactive oxygen species. Comparing MVs isolated from one or four nights, four DE-miRNAs that target genes regulating cell cycle progression and production of reactive oxygen species were found, but only eca-miR-214 was enriched in the MVs after four nights. In conclusion, after 4 days of cell culture, the profile of AMC miRNAs was altered, indicating a probable phenotypic transition versus a new cell culture environment and aging. After this time, MVs accumulated eca-miR-214, which may help cells survive or adapt to new culture conditions.

Canine amniotic membrane mesenchymal stromal/stem cells: Isolation, characterization and differentiation

The amniotic membrane can be considered as one of the sources of isolation of these cells, since it is found in the fetal maternal interface and has low immunogenicity. Mesenchymal stromal/stem cells (MSCs) have not been identified in canine amniotic membrane (AMC). Therefore, our objective was to isolate, culture, characterize and differentiate cells derived from canine amniotic membrane (AMC) and to verify its immunological and tumorigenic potential. For this, 12 dogs fetuses of each gestational age 32, 43 and 55 days were used, and the isolation and culture of the AMC were performed. We observed that the cells presented fibroblastoid morphology and high confluence even after freezing. We also observed that, when induced, they were able to differentiate into osteogenic, adipogenic, and chondrogenic cells, as well as being CD34- and CD105+. Regarding the immunological markers, we found that IL-1, IL-2, IL-6, IL-10 and MHC II were not expressed, whereas MHC I was expressed. After application of AMC cells in nude mice we can verify that there was no tumor formation. Based on this, we conclude that canine amniotic membrane is a good and accessible source for obtaining MSCs of low immunogenic and tumorigenic potential for veterinary therapeutic applications.

Glycan Profiling Analysis of Equine Amniotic Progenitor Mesenchymal Cells and Their Derived Extracellular Microvesicles

Equine amniotic mesenchymal cells (eAMCs) are involved in many mechanisms in tissue regenerative processes. Their secreted vesicles are important effectors in a wide array of biological processes, and contribute to in vivo healing of equine tendon lesions and endometrial inflammation. Glycoconjugates are involved in cellular recognition and in the efficient uptake of extracellular vesicles (EVs) by recipient cells. In this study, we evaluated the surface glycosylation pattern of eAMCs and their EVs from the eAMCs released in conditioned medium. We used a microarray procedure in which eAMCs and eAMC-EVs were spotted on microarray slides, and incubated with a panel of 14 biotinylated lectins and Cy3-conjugated streptavidin. Signal intensity was detected using a microarray scanner. Both eAMC and eAMC-EV microarrays interacted with all the lectins, indicating the presence of N- and O-linked glycans. With respect to eAMCs, eAMC-EVs, were found to be (1) enriched in Galβ1,3GalNAc terminating O-glycans, α2,3-linked sialoglycans, and high-mannose N-glycans (Con A); (2) diminished in N-acetyllactosamine, GalNAc, Gal, GlcNAc, and fucose terminating glycans; and (3) unchanged in α2,6 linked sialoglycans content. These results suggest that eAMC-EVs emerge from a specific eAMC microdomain, and that the high simultaneous presence of Galβ1,3GalNAc, α2,3 sialic acid, and high-mannose N-linked glycans may constitute markers of the eAMC-EVs. The role of these sugars in equine regenerative medicine requires further investigation.

Biologic Therapies for the Treatment of Knee Osteoarthritis

BACKGROUND

The use of biologic therapies for the management of knee osteoarthritis has increased, despite insufficient evidence of efficacy. Our aim was to complete a systematic review and analysis of reports utilizing the highest level-of-evidence evaluating: (1) platelet-rich plasma injections (PRPs); (2) bone marrow-derived mesenchymal stem cells (BMSCs); (3) adipose-derived mesenchymal stem cells (ADSCs); and (4) amnion-derived mesenchymal stem cells (AMSCs).

METHODS

PubMed, Embase, and Cochrane Library databases were queried for studies evaluating PRP injections, BMSCs, ADSCs, and AMSCs in patients with knee osteoarthritis. Of 1009 studies identified within the last 5 years, 123 met inclusion criteria. A comprehensive analysis of all levels-of-evidence was performed, as well as separate analysis on level-of-evidence I studies. Level-of-evidence was determined by the American Academy of Orthopedic Surgeons classification system.

RESULTS

Although the majority of PRP reports demonstrated improvements in pain and/or function, others revealed no substantial improvements. Similar findings were noted for BMSCs, ADSCs, and AMSCs. Assessments of BMSC studies yielded majority with positive clinical results, although short-lived. Studies on ADSCs revealed improved clinical outcomes, but equivocal radiographic outcomes. Studies evaluating AMSCs demonstrated improvements in pain and function, and decreased radiographic evidence of osteoarthritis.

CONCLUSION

Despite some promising early results for PRP, BMSC, ADSC, and AMSC therapies, the majority of level-of-evidence I studies have multiple problems: small sample sizes, potentially inappropriate control cohorts, short-term follow-up, and so on. Despite the limitations, there still appears to be evidence justifying their use for knee osteoarthritis management. More high-level, larger human studies utilizing standardized protocols are needed.

In Vitro Effect of Estradiol and Progesterone on Ovine Amniotic Epithelial Cells

Amniotic epithelial cells (AECs), an emerging source of extrafoetal stem cells, have recently attracted attention for their great regenerative potential. Since AEC amplifications are accompanied by the loss of their native epithelial phenotype and by the progressive reduction of relevant biological properties, the issue to be addressed is the development of effective culture protocols. In this context, recently, it has been demonstrated that progesterone (P₄) supplementation during ovine AEC (oAEC) expansion could prevent the undesirable epithelial-mesenchymal transition (EMT). In contrast, there is no information to date on the role of the other pregnancy steroids in culture. With this aim, the present study has been designed to clarify the impact of estradiol (E₂), alone or in combination with P₄ (12.5 μM and 25 μM), during oAEC amplification. Steroid supplementations were assessed by testing oAEC proliferation, stemness, EMT, and osteogenic or chondrogenic plasticity. The results indicated that EMT can be prevented exclusively in the presence of high doses of P₄, while it occurred rapidly in cells exposed to E₂ as denoted by protein (cytokeratin-8 and alpha-SMA) and gene expression (vimentin and snail) profiles. Moreover, steroid exposure was able to influence highly oAEC plasticity. Particularly, P₄-treated cells displayed a precommitment towards osteogenic lineage, confirmed by the upregulation of OCN, RUNX2, and the greater deposition of calcium nodules. Conversely, P₄ exposure inhibited oAEC chondrogenic differentiation, which was induced in E₂-treated cells as confirmed by the upregulation of chondrogenesis-related genes (SOX9, ACAN, and COL2A1) and by the accumulation of Alcian blue-positive extracellular matrix. Simultaneously, E₂-treated cells remained unresponsive to osteogenic inductive stimuli. In conclusion, media supplementation with high doses of steroids may be adopted to modulate phenotype and plasticity during oAEC amplification. Relevantly, the osteo or chondro steroid-induced precommitment may open unprecedented cell-based therapies to face the unsolved orthopaedic issues related to osteochondral regeneration.

Placental Stem Cells from Domestic Animals: Translational Potential and Clinical Relevance

The field of regenerative medicine is moving toward clinical practice in veterinary science. In this context, placenta-derived stem cells isolated from domestic animals have covered a dual role, acting both as therapies for patients and as a valuable cell source for translational models. The biological properties of placenta-derived cells, comparable among mammals, make them attractive candidates for therapeutic approaches. In particular, stemness features, low immunogenicity, immunomodulatory activity, multilineage plasticity, and their successful capacity for long-term engraftment in different host tissues after autotransplantation, allo-transplantation, or xenotransplantation have been demonstrated. Their beneficial regenerative effects in domestic animals have been proven using preclinical studies as well as clinical trials starting to define the mechanisms involved. This is, in particular, for amniotic-derived cells that have been thoroughly studied to date. The regenerative role arises from a mutual tissue-specific cell differentiation and from the paracrine secretion of bioactive molecules that ultimately drive crucial repair processes in host tissues (e.g., anti-inflammatory, antifibrotic, angiogenic, and neurogenic factors). The knowledge acquired so far on the mechanisms of placenta-derived stem cells in animal models represent the proof of concept of their successful use in some therapeutic treatments such as for musculoskeletal disorders. In the next future, legislation in veterinary regenerative medicine will be a key element in order to certify those placenta-derived cell-based protocols that have already demonstrated their safety and efficacy using rigorous approaches and to improve the degree of standardization of cell-based treatments among veterinary clinicians.

MicroRNAs of Equine Amniotic Mesenchymal Cell-derived Microvesicles and Their Involvement in Anti-inflammatory Processes

Cell-derived microvesicles (MVs) are a recently discovered mechanism of cell-to-cell communication. Our previous data show that MVs secreted by equine amniotic mesenchymal-derived cells (AMCs) are involved in downregulation of proinflammatory genes in lipopolysaccharide-stressed equine tendon and endometrial cells. The aim of the present study was to evaluate whether AMC-MVs contain selected microRNAs (miRNAs) involved in inflammation. Two pools of cells, derived from 3 amniotic membranes each, and their respective MVs were collected. Small RNAs were extracted and deep sequenced, followed by miRNA in silico detection. The analysis identified 1,285 miRNAs, which were quantified both in AMCs and MVs. Among these miRNAs, 401 were classified as Equus caballus miRNAs, 257 were predicted by homology with other species (cow, sheep, and goat), and 627 were novel candidate miRNAs. Moreover, 146 miRNAs differentially expressed (DE) in AMCs and MVs were identified, 36 of which were known and the remaining were novel. Among the known DE miRNAs, 17 showed higher expression in MVs. Three of these were validated by real time polymerase chain reaction: eca-miR-26, eca-miR-146a, and eca-miR-223. Gene ontology analysis of validated targets showed that the DE miRNAs in cells and MVs could be involved both in immune system regulation by modulating interleukin signaling and in the inflammatory process. In conclusion, this study suggests a significant role of AMCs in modulating immune response through cell–cell communication via MV-shuttling miRNAs.

Bone Tissue Engineering Using Human Cells: A Comprehensive Review on Recent Trends, Current Prospects, and Recommendations

The use of proper cells for bone tissue engineering remains a major challenge worldwide. Cells play a pivotal role in the repair and regeneration of the bone tissue in vitro and in vivo. Currently, a large number of differentiated (somatic) and undifferentiated (stem) cells have been used for bone reconstruction alone or in combination with different biomaterials and constructs (e.g., scaffolds). Although the results of the cell transplantation without any supporting or adjuvant material have been very effective with regard to bone healing. Recent advances in bone scaffolding are now becoming new players affecting the osteogenic potential of cells. In the present study, we have critically reviewed all the currently used cell sources for bone reconstruction and discussed the new horizons that are opening up in the context of cell-based bone tissue engineering strategies.

Amniotic Epithelial Stem Cells: Salient Features and Possible Therapeutic Role

This is a study of amniotic epithelial cells, which form the innermost layer of the amniotic membrane. These cells can be easily isolated and display peculiar and unique properties, such as plasticity and differentiation potential toward the 3 germinal layers, that may aid regeneration and/or repair of damaged or diseased tissues and organs. A robust literature based on in vitro, experimental, and clinical studies in large animals demonstrates that these cells can enhance the regeneration of tendons, bone, and articular cartilage. On the basis of these considerations, allotransplantation of human amniotic epithelial cells could be proposed for clinical trials in human orthopedic conditions.

Differences in the intrinsic chondrogenic potential of equine umbilical cord matrix and cord blood mesenchymal stromal/stem cells for cartilage regeneration

Umbilical cord blood mesenchymal stromal/stem cells (UCB-MSCs) and umbilical cord matrix MSCs (UCM-MSCs) have chondrogenic potential and are alternative sources to standard surgically derived bone marrow or adipose tissue collection for cartilage engineering. However, the majority of comparative studies explore neonatal MSCs potential only on ISCT benchmark assays accounting for some bias in the reproducibility between in vitro and in clinical studies. Therefore, we characterized equine UCB-MSCs and UCM-MSCs and investigated with particular attention their chondrogenesis potential in 3D culture with BMP-2 + TGF-ß1 in normoxia or hypoxia. We carried out an exhaustive characterization of the extracellular matrix generated by both these two types of MSCs after the induction of chondrogenesis through evaluation of hyaline cartilage, hypertrophic and osteogenic markers (mRNA, protein and histology levels). Some differences in hypoxia sensitivity and chondrogenesis were observed. UCB-MSCs differentiated into chondrocytes express an abundant, dense and a hyaline-like cartilage matrix. By contrast, despite their expression of cartilage markers, UCM-MSCs failed to express a relevant cartilage matrix after chondrogenic induction. Both MSCs types also displayed intrinsic differences at their undifferentiated basal status, UCB-MSCs expressing higher levels of chondrogenic markers whereas UCM-MSCs synthesizing higher amounts of osteogenic markers. Our results suggest that UCB-MSCs should be preferred for ex-vivo horse cartilage engineering. How those results should be translated to in vivo direct cartilage regeneration remains to be determined through dedicated study.

The ghrelin paradox in the control of equine chondrocyte function: The good and the bad

Increasing evidence suggests a role for ghrelin in the control of articular inflammatory diseases like osteoarthritis (OA). In the present study we examined the ability of ghrelin to counteract LPS-induced necrosis and apoptosis of chondrocytes and the involvement of GH secretagogue receptor (GHS-R)1a in the protective action of ghrelin. The effects of ghrelin (10^-7-10^-11 mol/L) on equine primary cultured chondrocytes viability and necrosis in basal conditions and under LPS treatment (100 ng/ml) were detected by using both acridine orange/propidium iodide staining and annexin-5/propidium iodide staining. The presence of GHS-R1a on chondrocytes was detected by Western Blot. The involvement of the GHS-R1a in the ghrelin effect against LPS-induced cytotoxicity was examined by pretreating chondrocytes with D-Lys3-GHRP-6, a specific GHS-R1a antagonist, and by using des-acyl ghrelin (DAG, 10^-7 and 10^-9 mol/L) which did not recognize the GHS-R 1a. Low ghrelin concentrations reduced chondrocyte viability whereas 10^-7 mol/L ghrelin protects against LPS-induced cellular damage. The protective effect of ghrelin depends on the interaction with the GHS-R1a since it is significantly reduced by D-Lys3-GHRP-6. The negative action of ghrelin involves caspase activation and could be due to an interaction with a GHS-R type different from the GHS-R1a recognized by both low ghrelin concentrations and DAG. DAG, in fact, induces a dose-dependent decrease in chondrocyte viability and exacerbates LPS-induced damage. These data indicate that ghrelin protects chondrocytes against LPS-induced damage via interaction with GHS-R1a and suggest the potential utility of local GHS-R1a agonist administration to treat articular inflammatory diseases such as OA.

Isolation and characterization of buffalo (bubalus bubalis) amniotic mesenchymal stem cells derived from amnion from the first trimester pregnancy

Amniotic mesenchymal stem cells (AMSCs) from livestock are valuable resources for animal reproduction and veterinary therapeutic. The purpose of this study is to explore a suitable way to isolate and culture the buffalo AMSCs (bAMSCs), and to identify their biological characteristics. Digestion with a combination of trypsin-EDTA and collagenase type I could obtain pure bAMSCs more effectively than trypsin-EDTA or collagenase type I alone. bAMSCs could proliferate steadily in vitro culture and exhibited fibroblastic-like morphology in vortex-shaped colony. bAMSCs were positive for MSC-specific markers CD44, CD90, CD105, CD73, β-integrin (CD29) and CD166, and pluripotent markers OCT4, SOX2, NANOG, REX-1, SSEA-1, SSEA-4 and TRA-1-81, but negative for hematopoietic markers CD34, CD45 and epithelial cells specific marker Cytokeratin 18. In addition, bAMSCs were capable of differentiating into adipogenic, osteogenic, chondrogenic and neural lineages, with expression of FABP4, Ost, ACAN, COL2A1, Nestin and β III-tubulin. Glycogen synthase kinase 3 inhibitor: kenpaullone promoted bAMSCs to differentiate into neural lineage. This study provides an effective protocol to obtain and characterize bAMSCs, which have proven useful as a cell resource for buffalo cell reprogramming studies and transgenic animal production.

Conditioned medium derived from rat amniotic epithelial cells confers protection against inflammation, cancer, and senescence

Amniotic epithelial cells (AECs) are a class of fetal stem cells that derives from the epiblast and resides in the amnion until birth. AECs are suitable candidates for regenerative medicine because of the ease of collection, their low immunogenicity and inability to form tumors after transplantation. Even though human AECs have been widely investigated, the fact remains that very little is known about AECs isolated from rat, one of the most common animal models in medical testing. In this study, we showed that rat AECs retained stemness properties and plasticity, expressed the pluripotency markers Sox2, Nanog, and Oct4 and were able to differentiate toward the osteogenic lineage. The addition of conditioned medium collected from rat AECs to lipopolysaccharide-activated macrophages elicited anti-inflammatory properties through a decrease of Tnfa expression and slowed tumor cell proliferation in vitro and in vivo. The senescence-associated secretory phenotype was also significantly lower upon incubation of senescent human IMR-90 fibroblast cells with conditioned medium from rat AECs. These results confirm the potential of AECs in the modulation of inflammatory mechanisms and open new therapeutic possibilities for regenerative medicine and anti-aging therapies as well.

Equine mesenchymal stem cells derived from endometrial or adipose tissue share significant biological properties, but have distinctive pattern of surface markers and migration

Adult stromal mesenchymal stem cells (MSCs) have been postulated as responsible for cell renewal in highly and continuously regenerative tissues such as the endometrium. MSCs have been identified in the endometrium of many species including humans, rodents, pets and some farm animals, but not in horses. The objective of this work was to isolate such cells from the endometrium of mares and to compare their main biological attributes with horse adipose-derived MSCs. Here we successfully isolated and characterized endometrial MSCs (eMSCs) from mares. Said cells showed fibroblast-like morphology, grew on plastic, had doubling population times of 46.4 ± 3.38 h, underwent tri-lineage (osteo, chondro and adipogenic) differentiation after appropriate inductions, migrated toward the attraction of fetal calf serum and displayed a pattern of surface markers commonly accepted for horse MSCs. All these are properties of MSCs. Some of these attributes were shared with equine adipose-derived MSCs, but the migration pattern of eMSC at 12 and 24 h after stimulation was reduced in comparison with adipose MSCs. Also, expression of CD44, CD90 and MHCI surface markers were dramatically down-regulated in eMSCs. In conclusion, equine-derived endometrial MSC share biological attributes with adipose MSC of this species, but displayed a different surface marker phenotype and an impaired migration ability. Conceivably, this phenotype is distinctive for MSC of this origin.

Hyaluronic acid coatings as a simple and efficient approach to improve MSC homing toward the site of inflammation

A major challenge in regenerative medicine is to improve therapeutic cells' delivery and targeting using an efficient and simple protocol. Mesenchymal stem cells (MSC) are currently employed for the treatment of inflammatory-based diseases, due to their powerful immunosoppressive potential. Here we report a simple and versatile method to transiently overexpress the hyaluronic acid (HA) receptor, CD44, on MSC membranes, to improve their homing potential towards an inflammatory site without affecting their behavior. The effect of HA-coatings on murine MSC was functionally determined both, in vitro and in vivo as a consequence of the transient CD44 overexpression induced by HA. Data obtained from the in vitro migration assay demonstrated a two-fold increase in the migratory potential of HA-treated MSC compared to untreated cells. In an LPS-induced inflamed ear murine model, HA-treated MSC demonstrated a significantly higher inflammatory targeting as observed at 72 hrs as compared to untreated cells. This increased accumulation for HA-treated MSC yielded a substantial reduction in inflammation as demonstrated by the decrease in the expression of pro-inflammatory markers and by the induction of a pro-regenerative environment.

Progesterone prevents epithelial-mesenchymal transition of ovine amniotic epithelial cells and enhances their immunomodulatory properties

The in vitro expansion is detrimental to therapeutic applications of amniotic epithelial cells (AEC), an emerging source of fetal stem cells. This study provides molecular evidences of progesterone (P4) role in preventing epithelial-mesenchymal transition (EMT) in ovine AEC (oAEC). oAEC amplified under standard conditions spontaneously acquired mesenchymal properties through the up-regulation of EMT-transcription factors. P4 supplementation prevented phenotype shift by inhibiting the EMT-inducing mechanism such as the autocrine production of TGF-β and the activation of intracellular-related signaling. The effect of P4 still persisted for one passage after steroid removal from culture as well as steroid supplementation promptly reversed mesenchymal phenotype in oAEC which have experienced EMT during amplification. Furthermore, P4 promoted an acute up-regulation of pluripotent genes whereas enhanced basal and LPS-induced oAEC anti-inflammatory response with an increase in anti-inflammatory and a decrease in pro-inflammatory cytokines expression. Altogether, these results indicate that P4 supplementation is crucial to preserve epithelial phenotype and to enhance biological properties in expanded oAEC. Therefore, an innovative cultural approach is proposed in order to improve therapeutic potential of this promising source of epithelial stem cells.

Isolation and characterization of equine native MSC populations

Background

In contrast to humans in which mesenchymal stem/stromal cell (MSC) therapies are still largely in the clinical trial phase, MSCs have been used therapeutically in horses for over 15 years, thus constituting a valuable preclinical model for humans. In human tissues, MSCs have been shown to originate from perivascular cells, namely pericytes and adventitial cells, which are identified by the presence of the cell surface markers CD146 and CD34, respectively. In contrast, the origin of MSCs in equine tissues has not been established, preventing the isolation and culture of defined cell populations in that species. Moreover, a comparison between perivascular CD146⁺ and CD34⁺ cell populations has not been performed in any species.

Methods

Immunohistochemistry was used to identify adventitial cells (CD34⁺) and pericytes (CD146⁺) and to determine their localization in relation to MSCs in equine tissues. Isolation of CD34⁺ (CD34⁺/CD146^–/CD144^–/CD45^–) and CD146⁺ (CD146⁺/CD34^–/CD144^–/CD45^–) cell fractions from equine adipose tissue was achieved by fluorescence-activated cell sorting. The isolated cell fractions were cultured and analyzed for the expression of MSC markers, using qPCR and flow cytometry, and for the ability to undergo trilineage differentiation. Angiogenic properties were analyzed in vivo using a chorioallantoic membrane (CAM) assay.

Results

Both CD34⁺ and CD146⁺ cells displayed typical MSC features, namely growth in uncoated tissue culture dishes, clonal growth when seeded at low density, expression of typical MSC markers, and multipotency shown by the capacity for trilineage differentiation. Of note, CD146⁺ cells were distinctly angiogenic compared with CD34⁺ and non-sorted cells (conventional MSCs), demonstrated by the induction of blood vessels in a CAM assay, expression of elevated levels of VEGFA and ANGPT1, and association with vascular networks in cocultures with endothelial cells, indicating that CD146⁺ cells maintain a pericyte phenotype in culture.

Conclusion

This study reports for the first time the successful isolation and culture of CD146⁺ and CD34⁺ cell populations from equine tissues. Characterization of these cells evidenced their distinct properties and MSC-like phenotype, and identified CD146⁺ cells as distinctly angiogenic, which may provide a novel source for enhanced regenerative therapies.

Isolation, culture, characterization and cryopreservation of stem cells derived from amniotic mesenchymal layer and umbilical cord tissue of bovine fetuses

ABSTRACT: Stem cells are undifferentiated cells with a high proliferation potential. These cells can be characterized by their in vivo ability to self-renew and to differentiate into specialized cell lines. The most used stem cell types, in both human and veterinary fields, are the mesenchymal stem cells (MSC) derived from bone marrow and adipose tissue. Nowadays, there is a great interest in using stem cells derived from fetal tissues, such as amniotic membrane (AM) and umbilical cord tissue (UCT), which can be obtained non-invasively at delivery time. Due to the scarcity of studies in bovine species, the aim of this study was to isolate, characterize, differentiate and cryopreserve MSC derived from the mesenchymal layer of amniotic membrane (AM), for the first time, and umbilical cord tissue (UCT) of dairy cow neonates after assisted delivery (AD) and from fetus at initial third of pregnancy (IT) obtained in slaughterhouse. Cells were isolated by enzymatic digestion of the tissue fragments with 0.1% collagenase solution. Six samples of AM and UCT at delivery time and six samples of AM and UCT at first trimester of pregnancy were subjected to morphology evaluation, imunophenotype characterization, in vitro osteogenic, adipogenic and chondrogenic differentiation and viability analysis after cryopreservation. All samples showed adherence to plastic and fibroblast-like morphology. Immunocytochemistry revealed expression of CD 44, NANOG and OCT-4 and lack of expression of MHC II in MSC from all samples. Flow cytometry demonstrated that cells from all samples expressed CD 44, did not or low expressed CD 34 (AM: IT-0.3%a, AD-3.4%b; UCT: 0.4%, 1.4%) and MHC II (AM: IT-1.05%a, AD-9.7%b; UCT: IT-0.7%a, AD-5.7%b). They were also capable of trilineage mesenchymal differentiation and showed 80% viability after cryopreservation. According to the results, bovine AM and UCT-derived cells, either obtained at delivery time or from slaughterhouse, are a painless and non-invasive source of MSC and can be used for stem cell banking.

Impact of Cryopreservation on Caprine Fetal Adnexa Derived Stem Cells and Its Evaluation for Growth Kinetics, Phenotypic Characterization, and Wound Healing Potential in Xenogenic Rat Model

This study was conducted to know the impact of cryopreservation on caprine fetal adnexa derived mesenchymal stem cells (MSCs) on the basic stem cell characteristics. Gravid caprine uteri (2-3 months) were collected from local abattoir to derive (amniotic fluid [cAF], amniotic sac [cAS], Wharton's jelly [cWJ], and cord blood [cCB]) MSCs and expanded in vitro. Cells were cryopreserved at 3rd passage (P3) using 10% DMSO. Post-thaw viability and cellular properties were assessed. Cells were expanded to determine growth kinetics, tri-lineage differentiation, localization, and molecular expression of MSCs and pluripotency markers; thereafter, these cells were transplanted in the full-thickness (2 × 2cm² ) rat skin wound to determine their wound healing potential. The post-thaw (pt) growth kinetics study suggested that cWJ MSCs expanded more rapidly with faster population doubling time (PDT) than that of other fetal adnexa MSCs. The relative mRNA expression of surface antigens (CD73, CD90, and CD 105) and pluripotency markers (Oct4, KLF, and cMyc) was higher in cWJ MSCs in comparison to cAS, cAF, and cCB MSCs post-thaw. The percent wound contraction on 7th day was more than 50% for all the MSC-treated groups (pre and post-thaw), against 39.55% in the control group. On day 28th, 99% and more wound contraction was observed in cAF, cAF-pt, cAS-pt, cWJ, cWJ-pt, and cCB, MSCs with better scores for epithelization, neovascularization, and collagen characteristics at a non-significant level. It is concluded that these MSCs could be successfully cryopreserved without altering their stemness and wound healing properties. J. Cell. Physiol. 232: 2186-2200, 2017. © 2016 Wiley Periodicals, Inc.

Phenotype and multipotency of rabbit (Oryctolagus cuniculus) amniotic stem cells

BACKGROUND

Stem cells are capable of unlimited self-renewal and are able to remain undifferentiated for extended periods of time prior to their differentiation into specific cell lineages. Because of the issues (ethical and religious) involved in the use of embryonic stem cells and the limited plasticity of adult stem cells, an alternative cell source could be foetal stem cells derived from extra-embryonic tissue, which are highly proliferative, grow in vitro and possess interesting immunogenic characteristics. As a result, the amniotic membrane of several species has been studied as an important new source of stem cells.

METHODS

Here, we cultured and characterized mesenchymal progenitor cells derived from the rabbit amniotic membrane, and investigated their differentiation potential. In total, amniotic membranes were collected from eight rabbit foetuses and were isolated by the explant technique. The obtained cells were cultured in DMEM-HIGH glucose and incubated at 37 °C in a humidified atmosphere with 5% CO2.

RESULTS

The cells adhered to the culture plates and showed a high proliferative capacity with fibroblast-like morphologies. The cells showed a positive response for markers for the cytoskeleton, mesenchymal stem cells and proliferation, pluripotency and haematopoietic precursor stem cells. However, the cells were negative for CD45, a marker of haematopoietic cells. Furthermore, the cells had the capacity to be induced to differentiate into osteogenic, adipogenic and chondrogenic lineages. In addition, when the cells were injected into nude mice, we did not observe the formation of tumours.

CONCLUSIONS

In summary, our results demonstrate that multipotent mesenchymal stem cells can be obtained from the rabbit amniotic membrane for possible use in future cell therapy applications.

Conditioned medium: a new alternative for cryopreservation of equine umbilical cord mesenchymal stem cells

Cryopreservation is a feasible alternative to maintaining several cell lines, particularly for immediate therapeutic use, transportation of samples, and implementation of new in vitro studies. This work parts from the hypothesis that the medium of cryopreservation composed by 90% of conditioned medium (CM) supports cryopreservation of equine umbilical cord intervascular matrix mesenchymal stem cells (UCIM-MSCs), allowing the maintenance of the biological properties for the establishment of cell banks intended for therapeutic use and in vitro studies. Thus, we evaluated the viability, apoptosis/necrosis rates, immunophenotypic profile (IP), chromosomal stability, clonicity, and differentiation potential of UCIM-MSCs cryopreserved with four different mediums (with FBS: M1, M3, M4 and without FBS: M2). After 3 months of cryopreservation, samples were thawed and analyzed. The potential of differentiation in the mesodermal lineages, clonicity, and the chromosomal stability were maintained after cryopreservation of UCIM-MSCs with medium containing FBS. Changes (P < 0.05) at IP for some markers were observed at cells cryopreserved with medium M1-M3. Only the UCIM-MSCs cryopreserved with the CM (M4) had similar viability post-thaw (P = 0.23) when compared with fresh cells. We proved the hypothesis that the medium of cryopreservation containing CM supports the cryopreservation of UCIM-MSCs, at the experimental conditions, being the medium that better maintains the biological characteristics observed at fresh cells. Thus, future studies of UCIM-MSCs secretome should be conducted to better understand the beneficial and protective effects of the CM during the freezing process.

Fetal Membranes-Derived Stem Cells Microenvironment

Recently, the regenerative medicine has been trying to congregate different areas such as tissue engineering and cellular therapy, in order to offer effective treatments to overcome several human and veterinary medical problems. In this regard, fetal membranes have been proposed as a powerful source for obtainment of multipotent stem cells with low immunogenicity, anti-inflammatory properties and nontumorigenicity properties for the treatment of several diseases, including replacing cells lost due to tissue injuries or degenerative diseases. Morpho-physiological data have shown that fetal membranes, especially the yolk sac and amnion play different functions according to the gestational period, which are direct related to the features of the microenvironment that their cells are subject. The characteristics of the microenvironment affect or controls important cellular events involved with proliferation, division and maintenance of the undifferentiated stage or differentiation, especially acting on the extracellular matrix components. Considering the importance of the microenvironment and the diversity of embryonic and fetal membrane-derived stem cells, this chapter will addressed advances in the isolation, phenotyping, characteristics of the microenvironment, and applications of yolk sac and amniotic membrane-derived stem cells for human and veterinary regenerative medicine.

Microvesicles secreted from equine amniotic-derived cells and their potential role in reducing inflammation in endometrial cells in an in-vitro model

Background

It is known that a paracrine mechanism exists between mesenchymal stem cells and target cells. This process may involve microvesicles (MVs) as an integral component of cell-to-cell communication.

Methods

In this context, this study aims to understand the efficacy of MVs in in-vitro endometrial stressed cells in view of potential healing in in-vivo studies. For this purpose, the presence and type of MVs secreted by amniotic mesenchymal stem cells (AMCs) were investigated and the response of endometrial cells to MVs was studied using a dose-response curve at different concentrations and times. Moreover, the ability of MVs to counteract the in vitro stress in endometrial cells induced by lipopolysaccharide was studied by measuring the rate of apoptosis and cell proliferation, the expression of some pro-inflammatory genes such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin 1β (IL-1β), and metalloproteinases (MMP) 1 and 13, and the release of some pro- or anti-inflammatory cytokines.

Results

MVs secreted by the AMCs ranged in size from 100 to 200 nm. The incorporation of MVs was gradual over time and peaked at 72 h. MVs reduced the apoptosis rate, increased cell proliferation values, downregulated pro-inflammatory gene expression, and decreased the secretion of pro-inflammatory cytokines.

Conclusion

Our data suggest that some microRNAs could contribute to counteracting in-vivo inflammation of endometrial tissue.

Isolation, molecular characterization, and in vitro differentiation of bovine Wharton jelly-derived multipotent mesenchymal cells

Extrafetal tissues are a noncontroversial and inexhaustible source of mesenchymal stem cells that can be harvested noninvasively at low cost. In the veterinary field, as in man, stem cells derived from extrafetal tissues express plasticity, reduced immunogenicity, and have high anti-inflammatory potential making them promising candidates for treatment of many diseases. Umbilical cord mesenchymal cells have been isolated and characterized in different species and have recently been investigated as potential candidates in regenerative medicine. In this study, cells derived from bovine Wharton jelly (WJ) were isolated for the first time by enzymatic methods, frozen/thawed, cultivated for at least 10 passages, and characterized. Wharton jelly-derived cells readily attached to plastic culture dishes displaying typical fibroblast-like morphology and, although their proliferative capacity decreased to the seventh passage, these cells showed a mean doubling time of 34.55 ± 6.33 hours and a mean frequency of one colony-forming unit fibroblast like for every 221.68 plated cells. The results of molecular biology studies and flow cytometry analyses revealed that WJ-derived cells showed the typical antigen profile of mesenchymal stem cells and were positive for CD29, CD44, CD105, CD166, Oct-4, and c-Myc. They were negative for CD34 and CD14. Remarkably, WJ-derived cells showed differentiation ability. After culture in induced media, WJ-derived cells were able to differentiate into osteogenic, adipogenic, chondrogenic, and neurogenic lines as shown by positive staining and expression of specific markers. On polymerase chain reaction analysis, these cells were negative for MHC-II and positive for MHC-I, thus reinforcing the role of extrafetal tissue as an allogenic source for bovine cell-based therapies. These results provide evidence that bovine WJ-derived cells may have the potential to differentiate to repair damaged tissues and reinforce the importance of extrafetal tissues as stem cell sources in veterinary regenerative medicine. A more detailed evaluation of their immunologic properties is necessary to better understand their potential role in cellular therapy.

Evaluation of amniotic mesenchymal cell derivatives on cytokine production in equine alveolar macrophages: an in vitro approach to lung inflammation

Background

Data obtained in both animal models and clinical trials suggest that cell-based therapies represent a potential therapeutic strategy for lung repair and remodeling. Recently, new therapeutic approaches based on the use of stem cell derivatives (e.g., conditioned medium (CM) and microvesicles (MVs)) to regenerate tissues and improve their functions were proposed. The aim of this study was to investigate the immunomodulatory effects of equine amniotic mesenchymal cell derivatives on lipopolysaccharide (LPS)-induced cytokine production in equine alveolar macrophages, which may be beneficial in lung inflammatory disorders such as recurrent airway obstruction (RAO) in horses. RAO shares many features with human asthma, including an increased number of cells expressing mRNA for interleukin (IL)-4 and IL-5 and a decreased expression of IFN-γ in bronchoalveolar lavage fluid (BALF) of affected horses.

Methods

The release of TNF-α, IL-6, and TGF-β1 at different time points (1, 24, 48, and 72 h) was measured in equine alveolar macrophages stimulated or not with LPS (10 and 100 ng/mL) in the presence or absence of 10 % CM or 50 × 10⁶ MVs/mL.

Cytokines were measured using commercially available ELISA kits. For multiple comparisons, analysis of variance was used with Tukey post-hoc test. Differences were considered significant at p ≤ 0.05.

Results

Significant modulatory effects of CM on LPS-induced TNF-α release at 24 h, and of both CM and MVs on TNF-α release at 48 h were observed. A trend toward a modulatory effect of both CM and MVs on the release of TGF-β and possibly IL-6 was visible over time.

Conclusions

Results support the potential use of CM and MVs in lung regenerative medicine, especially in situations in which TGF-β may be detrimental, such as respiratory allergy. Further studies should evaluate the potential clinical applications of CM and MVs in equine lung diseases, such as RAO and other inflammatory disorders.

Mesenchymal stem cells for tendon healing: what is on the horizon?

Tendon injuries are a noteworthy morbidity but at present there are few effective scientifically proven treatments. In recent decades, a number of new strategies including tissue engineering with mesenchymal stem cells (MSCs) have been proposed to enhance tendon healing. Although MSCs are an interesting and promising approach, many questions regarding their use in tendon repair remain unanswered. This descriptive overview of the literature of the last decade explores the in vivo studies on tendon healing, in small and large animal models, which used MSCs harvested from different tissues, and the state of the art in clinical applications. It was observed that there are still doubts about the optimum amount of MSCs to use and their source and the type of scaffolds to deliver the cells. Thus, further studies are needed to determine the best protocol for MSC use in tendon healing. Copyright © 2016 John Wiley & Sons, Ltd.

Hominis Placenta facilitates hair re-growth by upregulating cellular proliferation and expression of fibroblast growth factor-7

Background

Hominis Placenta (HP) known as a restorative medicine in Traditional Chinese Medicine (TCM), has been widely applied in the clinics of Korea and China as an anti-aging agent to enhance the regeneration of tissue. This study was conducted to investigate whether topical treatment of HP promotes hair regrowth in the animal model.

Methods

The dorsal hairs of 8-week-old C57BL/6 mice were depilated to synchronize hair follicles to the anagen phase. HP was applied topically once a day for 15 days. Hair growth was evaluated visually and microscopically. The incorporation of bromodeoxyuridine (BrdU) and expression of proliferating cell nuclear antigen (PCNA), fibroblast growth factor-7 (FGF-7) in dorsal skin tissue was examined by immunohistochemical analysis. Reverse transcription polymerase chain reaction (RT-PCR) was used to measure the mRNA expression of FGF-7.

Results

HP exhibited potent hair growth-promoting activity in C57BL/6 mice. Gross examination indicated that HP markedly increased hair regrowth as well as hair density and diameter. Histologic analysis showed that HP treatment enhanced the anagen induction of hair follicles.

Immunohistochemical analysis revealed that BrdU incorporation and the expressions of PCNA were increased by treatment of HP. HP treatment significantly increased the expression of FGF-7, which plays pivotal roles to maintain anagen phase both protein and mRNA levels.

Conclusions

Taken together, our results indicate that HP has a potent hair growth-promoting activity; therefore, it may be a good candidate for the treatment of alopecia.

A Comparative Study of Growth Kinetics, In Vitro Differentiation Potential and Molecular Characterization of Fetal Adnexa Derived Caprine Mesenchymal Stem Cells

The present study was conducted with an objective of isolation, in vitro expansion, growth kinetics, molecular characterization and in vitro differentiation of fetal adnexa derived caprine mesenchymal stem cells. Mid-gestation gravid caprine uteri (2–3 months) were collected from abattoir to derive mesenchymal stem cells (MSCs) from fetal adnexa {amniotic fluid (cAF), amniotic sac (cAS), Wharton’s jelly (cWJ) and cord blood (cCB)} and expanded in vitro. These cultured MSCs were used at the 3^rd passage (P3) to study growth kinetics, localization as well as molecular expression of specific surface antigens, pluripotency markers and mesenchymal tri-lineage differentiation. In comparison to cAF and cAS MSCs, cWJ and cCB MSCs showed significantly (P<0.05) higher clonogenic potency, faster growth rate and low population doubling (PDT) time. All the four types of MSCs were positive for alkaline phosphatase (AP) and differentiated into chondrogenic, osteogenic, and adipogenic lineages. These stem cells expressed MSC surface antigens (CD73, CD90 and CD105) and pluripotency markers (Oct4, Sox2, Nanog, KLF, cMyc, FoxD3) but did not express CD34, a hematopoietic stem cell marker (HSC) as confirmed by RT-PCR, immunocytochemistry and flow cytometric analysis. The relative mRNA expression of MSC surface antigens (CD73, CD90 and CD105) was significantly (P<0.05) higher in cWJ MSCs compared to the other cell lines. The mRNA expression of Oct4 was significantly (P<0.05) higher in cWJ, whereas mRNA expression of KLF and cMyc was significantly (P<0.05) higher in cWJ and cAF than that of cAS and cCB. The comparative assessment revealed that cWJ MSCs outperformed MSCs from other sources of fetal adnexa in terms of growth kinetics, relative mRNA expression of surface antigens, pluripotency markers and tri-lineage differentiation potential, hence, these MSCs could be used as a preferred source for regenerative medicine.

Chondroitin Sulfate Immobilized on a Biomimetic Scaffold Modulates Inflammation While Driving Chondrogenesis

Costs associated with degenerative inflammatory conditions of articular cartilage are exponentially increasing in the aging population, and evidence shows a strong clinical need for innovative therapies. Stem cell-based therapies represent a promising strategy for the treatment of innumerable diseases. Their regenerative potential is undeniable, and it has been widely exploited in many tissue-engineering approaches, especially for bone and cartilage repair. Their immune-modulatory capacities in particular make stem cell-based therapeutics an attractive option for treating inflammatory diseases. However, because of their great plasticity, mesenchymal stem cells (MSCs) are susceptible to different external factors. Biomaterials capable of concurrently providing physical support to cells while acting as synthetic extracellular matrix have been established as a valuable strategy in cartilage repair. Here we propose a chondroitin sulfate-based biomimetic scaffold that recapitulates the physicochemical features of the chondrogenic niche and retains MSC immunosuppressive potential in vitro, either in response to a proinflammatory cytokine or in the presence of stimulated peripheral blood mononuclear cells. In both cases, a significant increase in the production of molecules associated with immunosuppression (nitric oxide and prostaglandins), as well as in the expression of their inducible enzymes (iNos, Pges, Cox-2, and Tgf-β). When implanted subcutaneously in rats, our scaffold revealed a reduced infiltration of leukocytes at 24 hours, which correlated with a greater upregulation of genes involved in inflammatory cell apoptotic processes. In support of its effective use in tissue-engineering applications of cartilage repair, the potential of the proposed platform to drive chondrogenic and osteogenic differentiation of MSC was also proven.

SIGNIFICANCE

Recently, increasing clinical evidence has highlighted the important role of proinflammatory mediators and infiltrating inflammatory cell populations inducing chronic inflammation and diseases in damaged cartilage. This work should be of broad interest because it proposes an implantable biomimetic material, which holds the promise for a variety of medical conditions that necessitate the functional restoration of damaged cartilage tissue (such as trauma, diseases, deformities, or cancer).

Does the Bovine Pre-Ovulatory Follicle Harbor Progenitor Stem Cells?

Recent studies have revealed the presence of a mesenchymal stem cell (MSC) population in human and in gilt granulosa cells (GCs), thus increasing the interest in identifying the same population in the bovine species. We first isolated GCs by scraping from bovine preovulatory follicles and then tested several different media to define the ideal conditions to select granulosa-derived stem cells. Although expressing MSC-associated markers, none of the media tested proven to be efficient in selecting MSC-like cells that were able to differentiate into mesodermic or ectodermic lineages. We performed another experimental approach exposing cells to a chemical stress, such as lowering of pH, as a system to select a more plastic population. Following the treatment, granulosa-specific granulose markers [follicle-stimulating hormone receptor (FSHR), follistatin (FST), and leukemia inhibitory factor receptor (LIFR)] were lost in bovine GCs, whereas an increase in multi- (CD29, CD44, CD73) and pluripotent (Oct-4 and c-Myc) genes was noticed. The stress allowed up-regulation of tumor necrosis factor-α and interleukin-1β expression and the dedifferentiation of GCs, which was demonstrated by differentiation studies. Indeed, pH-treated cells were able to differentiate into the mesodermic and ectodermic lineages, thus suggesting that the chemical stress allows for the selection of cells that are more prone to adjust and respond to the environmental changes.

Nanotechnology for mesenchymal stem cell therapies

Mesenchymal stem cells (MSC) display great proliferative, differentiative, chemotactic, and immune-modulatory properties required to promote tissue repair. Several clinical trials based on the use of MSC are currently underway for therapeutic purposes. The aim of this article is to examine the current trends and potential impact of nanotechnology in MSC-driven regenerative medicine. Nanoparticle-based approaches are used as powerful carrier systems for the targeted delivery of bioactive molecules to ensure MSC long-term maintenance in vitro and to enhance their regenerative potential. Nanostructured materials have been developed to recapitulate the stem cell niche within a tissue and to instruct MSC toward the creation of regeneration-permissive environment. Finally, the capability of MSC to migrate toward the site of injury/inflammation has allowed for the development of diagnostic imaging systems able to monitor transplanted stem cell bio-distribution, toxicity, and therapeutic effectiveness.

Peculiarity of Porcine Amniotic Membrane and Its Derived Cells: A Contribution to the Study of Cell Therapy from a Large Animal Model

The aim of this work was to provide, for the first time, a protocol for isolation and characterization of stem cells from porcine amniotic membrane in view of their potential uses in regenerative medicine. From three samples of allanto-amnion recovered at delivery, the amniotic membrane was stripped from overlying allantois and digested with trypsin and collagenase to isolate epithelial (amniotic epithelial cells [AECs]) and mesenchymal cells, respectively. Proliferation, differentiation, and characterization studies by molecular biology and flow cytometry were performed. Histological examination revealed very few mesenchymal cells in the stromal layer, and a cellular yield of AECs of 10 × 10(6)/gram of digested tissue was achieved. AECs readily attached to plastic culture dishes displaying typical cuboidal morphology and, although their proliferative capacity decreased to the fifth passage, AECs showed a mean doubling time of 24.77 ± 6 h and a mean frequency of one fibroblast colony-forming unit (CFU-F) for every 116.75 plated cells. AECs expressed mesenchymal stem cell (MSC) mRNA markers (CD29, CD166, CD90, CD73, CD117) and pluripotent markers (Nanog and Oct 4), whereas they were negative for CD34 and MHCII. Mesodermic, ectodermic, and endodermic differentiation was confirmed by staining and expression of specific markers. We conclude that porcine amniotic membrane can provide an attractive source of stem cells that may be a useful tool for biomedical research.

Enhanced osteogenic potential of mesenchymal stem cells from cortical bone: a comparative analysis

Introduction

Mesenchymal stem cells (MSCs) hold great promise for regenerative therapies in the musculoskeletal system. Although MSCs from bone marrow (BM-MSCs) and adipose tissue (AD-MSCs) have been extensively characterized, there is still debate as to the ideal source of MSCs for tissue-engineering applications in bone repair.

Methods

MSCs were isolated from cortical bone fragments (CBF-MSCs) obtained from patients undergoing laminectomy, selected by fluorescence-activated cell sorting analysis, and tested for their potential to undergo mesodermic differentiation. CBF-MSCs were then compared with BM-MSCs and AD-MSCs for their colony-forming unit capability and osteogenic potential in both normoxia and hypoxia. After 2 and 4 weeks in inducing media, differentiation was assessed qualitatively and quantitatively by the evaluation of alkaline phosphatase (ALP) expression and mineral deposition (Von Kossa staining). Transcriptional activity of osteoblastogenesis-associated genes (Alp, RUNX2, Spp1, and Bglap) was also analyzed.

Results

The cortical fraction of the bone contains a subset of cells positive for MSC-associated markers and capable of tri-lineage differentiation. The hypoxic conditions were generally more effective in inducing osteogenesis for the three cell lines. However, at 2 and 4 weeks, greater calcium deposition and ALP expression were observed in both hypoxic and normoxic conditions in CBF-MSCs compared with AD- and BM-MSCs. These functional observations were further corroborated by gene expression analysis, which showed a significant upregulation of Bglap, Alp, and Spp1, with a 22.50 (±4.55)-, 46.56 (±7.4)-, 71.46 (±4.16)-fold increase compared with their uninduced counterparts.

Conclusions

This novel population of MSCs retains a greater biosynthetic activity in vitro, which was found increased in hypoxic conditions. The present study demonstrates that quantitative differences between MSCs retrieved from bone marrow, adipose, and the cortical portion of the bone with respect to their osteogenic potential exist and suggests the cortical bone as suitable candidate to use for orthopedic tissue engineering and regenerative medicine.

Cell Surface Glycan Changes in the Spontaneous Epithelial-Mesenchymal Transition of Equine Amniotic Multipotent Progenitor Cells

Amniotic epithelial cells (AECs) spontaneously transform into amniotic mesenchymal cells (AMCs) in vitro during cell culture. Glycocalyx was analyzed to identify the glycan pattern in AECs, AMCs and epithelial-mesenchymal transdifferentiated cells (EMTCs). Pure cell cultures were derived using cloned AEC and AMC cell lines obtained by the dilution technique from amniotic membranes. Mesenchymal cells generated by differentiation of clonal epithelial cells were considered transdifferentiated. Immunocytoscreen, in vitro multipotent differentiation and molecular characterization of EMTCs were performed. In combination with saponification and sialidase digestion, a panel of 12 lectins was used to analyze the glycan pattern of AEC, AMC and EMTC glycocalyx. Cytokeratin cell markers were lost in EMTCs and typical mesenchymal markers, such as vimentin, appeared. These cells retained their differentiation potential. Lectin histochemistry revealed a cell-specific glycan profile. Galactose (Gal)β1,4GlcNAc, Neu5Acα2,6Gal/GalNAc and N-acetyl neuraminic (sialic) acid (NeuNAc)α2,3Galβ1,3(±NeuNAcα2,6)GalNAc were highly expressed on the surface of all the amniotic cell cultures. AECs expressed asialoglycans with terminal GalNAc and GlcNAc. More highly mannosylated N-linked glycans and NeuNAcα2,3Galβ1,3GalNAc in O-linked glycans were expressed by EMTCs, but these cells had fewer glycans ending with fucose (Fuc), Gal, GlcNAc and GalNAc than AECs. GlcNAc- and GalNAc-terminating glycans were similarly expressed on the glycocalyx of the mesenchymal cell populations (EMTCs and AMCs). These results demonstrate for the first time that the spontaneous epithelial-mesenchymal transition (EMT) of equine amnion cells is characterized by cell surface glycan remodeling and that glycosylation changes result in a cell type-specific glycan profile. The glycopattern of equine amnion spontaneous EMTCs differs from EMT of tumoral cells.