Deer antler stem cell niche: An interesting perspective.

In recent years, there has been considerable exploration into methods aimed at enhancing the regenerative capacity of transplanted and/or tissue-resident cells. Biomaterials, in particular, have garnered significant interest for their potential to serve as natural scaffolds for cells. In this editorial, we provide commentary on the study by Wang et al, in a recently published issue of World J Stem Cells, which investigates the use of a decellularized xenogeneic extracellular matrix (ECM) derived from antler stem cells for repairing osteochondral defects in rat knee joints. Our focus lies specifically on the crucial role of biological scaffolds as a strategy for augmenting stem cell potential and regenerative capabilities, thanks to the establishment of a favorable microenvironment (niche). Stem cell differentiation heavily depends on exposure to intrinsic properties of the ECM, including its chemical and protein composition, as well as the mechanical forces it can generate. Collectively, these physicochemical cues contribute to a bio-instructive signaling environment that offers tissue-specific guidance for achieving effective repair and regeneration. The interest in mechanobiology, often conceptualized as a form of "structural memory", is steadily gaining more validation and momentum, especially in light of findings such as these.

Cytochalasin B Influences Cytoskeletal Organization and Osteogenic Potential of Human Wharton's Jelly Mesenchymal Stem Cells.

Among perinatal stem cells of the umbilical cord, human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) are of great interest for cell-based therapy approaches in regenerative medicine, showing some advantages over other MSCs. In fact, hWJ-MSCs, placed between embryonic and adult MSCs, are not tumorigenic and are harvested with few ethical concerns. Furthermore, these cells can be easily cultured in vitro, maintaining both stem properties and a high proliferative rate for several passages, as well as trilineage capacity of differentiation. Recently, it has been demonstrated that cytoskeletal organization influences stem cell biology. Among molecules able to modulate its dynamics, Cytochalasin B (CB), a cyto-permeable mycotoxin, influences actin microfilament polymerization, thus affecting several cell properties, such as the ability of MSCs to differentiate towards a specific commitment. Here, we investigated for the first time the effects of a 24 h-treatment with CB at different concentrations (0.1-3 µM) on hWJ-MSCs. CB influenced the cytoskeletal organization in a dose-dependent manner, inducing changes in cell number, proliferation, shape, and nanomechanical properties, thus promoting the osteogenic commitment of hWJ-MSCs, as confirmed by the expression analysis of osteogenic/autophagy markers.

Mechanobiology: A landscape for reinterpreting stem cell heterogeneity and regenerative potential in diseased tissues.

Mechanical forces play a fundamental role in cellular dynamics from the molecular level to the establishment of complex heterogeneity in somatic and stem cells. Here, we highlight the role of cytoskeletal mechanics and extracellular matrix in generating mechanical forces merging into oscillatory synchronized patterns. We discuss how cellular mechanosensing/-transduction can be modulated by mechanical forces to control tissue metabolism and set the basis for nonpharmacologic tissue rescue. Control of bone anabolic activity and repair, as well as obesity prevention, through a fine-tuning of the stem cell morphodynamics are highlighted. We also discuss the use of mechanical forces in the treatment of cardiovascular diseases and heart failure through the fine modulation of stem cell metabolic activity and regenerative potential. We finally focus on the new landscape of delivering specific mechanical stimuli to reprogram tissue-resident stem cells and enhance our self-healing potential, without the need for stem cell or tissue transplantation.

Cytochalasin B Modulates Nanomechanical Patterning and Fate in Human Adipose-Derived Stem Cells.

Cytoskeletal proteins provide architectural and signaling cues within cells. They are able to reorganize themselves in response to mechanical forces, converting the stimuli received into specific cellular responses. Thus, the cytoskeleton influences cell shape, proliferation, and even differentiation. In particular, the cytoskeleton affects the fate of mesenchymal stem cells (MSCs), which are highly attractive candidates for cell therapy approaches due to their capacity for self-renewal and multi-lineage differentiation. Cytochalasin B (CB), a cyto-permeable mycotoxin, is able to inhibit the formation of actin microfilaments, resulting in direct effects on cell biological properties. Here, we investigated for the first time the effects of different concentrations of CB (0.1-10 µM) on human adipose-derived stem cells (hASCs) both after 24 h (h) of CB treatment and 24 h after CB wash-out. CB influenced the metabolism, proliferation, and morphology of hASCs in a dose-dependent manner, in association with progressive disorganization of actin microfilaments. Furthermore, the removal of CB highlighted the ability of cells to restore their cytoskeletal organization. Finally, atomic force microscopy (AFM) revealed that cytoskeletal changes induced by CB modulated the viscoelastic properties of hASCs, influencing their stiffness and viscosity, thereby affecting adipogenic fate.

Cell Responsiveness to Physical Energies: Paving the Way to Decipher a Morphogenetic Code.

We discuss emerging views on the complexity of signals controlling the onset of biological shapes and functions, from the nanoarchitectonics arising from supramolecular interactions, to the cellular/multicellular tissue level, and up to the unfolding of complex anatomy. We highlight the fundamental role of physical forces in cellular decisions, stressing the intriguing similarities in early morphogenesis, tissue regeneration, and oncogenic drift. Compelling evidence is presented, showing that biological patterns are strongly embedded in the vibrational nature of the physical energies that permeate the entire universe. We describe biological dynamics as informational processes at which physics and chemistry converge, with nanomechanical motions, and electromagnetic waves, including light, forming an ensemble of vibrations, acting as a sort of control software for molecular patterning. Biomolecular recognition is approached within the establishment of coherent synchronizations among signaling players, whose physical nature can be equated to oscillators tending to the coherent synchronization of their vibrational modes. Cytoskeletal elements are now emerging as senders and receivers of physical signals, "shaping" biological identity from the cellular to the tissue/organ levels. We finally discuss the perspective of exploiting the diffusive features of physical energies to afford in situ stem/somatic cell reprogramming, and tissue regeneration, without stem cell transplantation.

Protective effects of exosomes derived from lyophilized porcine liver against acetaminophen damage on HepG2 cells.

BACKGROUND: Recently, extracellular vesicles have come to the fore following their emerging role in cell communication, thanks to their ability to reach cells into the human body without dissipating their cargo, transferring biological active molecules, such as proteins, nucleic acids, lipids, etc. They appear as a promising tool in medicine, because of their capability to modulate cellular response in recipient cells. Moreover, a considerable number of publications suggests that exosome uptake is selective but not specific, and it can cross species and cell-type boundaries. This study aims to explore the potential role of porcine liver derived extracellular vesicles, exosomes in particular, to protect human cells from acute damage induced by acetaminophen. METHODS: Extracellular vesicles were isolated from porcine lyophilized liver using polymer-based precipitation and a further enrichment was performed using affinity beads. The effects of obtained fractions, total extracellular vesicles and enriched extracellular vesicles, were assessed on human liver derived HepG2 cells. Cell growth and survival were tested, with MTT and area coverage analysis designed by us, as well as protein expression, with immunofluorescence and Western blot. Oxidative stress in live cells was also measured with fluorogenic probes. RESULTS: After proving that porcine extracellular vesicles did not have a toxic effect on HepG2, quite the contrary total extracellular vesicle fraction improved cell growth, we investigated their protective capability with a preconditioning strategy in APAP-induced damage. EVs displayed not only the ability to strongly modulate cell survival responses, but they also were able to boost cell cycle progression. CONCLUSIONS: Extracellular vesicles derived from farm animal food derivatives are able to modulate human hepatic cell metabolism, also improving cell survival in a damaged context.

Unveiling the morphogenetic code: A new path at the intersection of physical energies and chemical signaling.

In this editorial, we discuss the remarkable role of physical energies in the control of cell signaling networks and in the specification of the architectural plan of both somatic and stem cells. In particular, we focus on the biological relevance of bioelectricity in the pattern control that orchestrates both developmental and regenerative pathways. To this end, the narrative starts from the dawn of the first studies on animal electricity, reconsidering the pioneer work of Harold Saxton Burr in the light of the current achievements. We finally discuss the most recent evidence showing that bioelectric signaling is an essential component of the informational processes that control pattern specification during embryogenesis, regeneration, or even malignant transformation. We conclude that there is now mounting evidence for the existence of a Morphogenetic Code, and that deciphering this code may lead to unprecedented opportunities for the development of novel paradigms of cure in regenerative and precision medicine.

Intracrine Endorphinergic Systems in Modulation of Myocardial Differentiation.

A wide variety of peptides not only interact with the cell surface, but govern complex signaling from inside the cell. This has been referred to as an "intracrine" action, and the orchestrating molecules as "intracrines". Here, we review the intracrine action of dynorphin B, a bioactive end-product of the prodynorphin gene, on nuclear opioid receptors and nuclear protein kinase C signaling to stimulate the transcription of a gene program of cardiogenesis. The ability of intracrine dynorphin B to prime the transcription of its own coding gene in isolated nuclei is discussed as a feed-forward loop of gene expression amplification and synchronization. We describe the role of hyaluronan mixed esters of butyric and retinoic acids as synthetic intracrines, controlling prodynorphin gene expression, cardiogenesis, and cardiac repair. We also discuss the increase in prodynorphin gene transcription and intracellular dynorphin B afforded by electromagnetic fields in stem cells, as a mechanism of cardiogenic signaling and enhancement in the yield of stem cell-derived cardiomyocytes. We underline the possibility of using the diffusive features of physical energies to modulate intracrinergic systems without the needs of viral vector-mediated gene transfer technologies, and prompt the exploration of this hypothesis in the near future.

Physical energies to the rescue of damaged tissues.

Rhythmic oscillatory patterns sustain cellular dynamics, driving the concerted action of regulatory molecules, microtubules, and molecular motors. We describe cellular microtubules as oscillators capable of synchronization and swarming, generating mechanical and electric patterns that impact biomolecular recognition. We consider the biological relevance of seeing the inside of cells populated by a network of molecules that behave as bioelectronic circuits and chromophores. We discuss the novel perspectives disclosed by mechanobiology, bioelectromagnetism, and photobiomodulation, both in term of fundamental basic science and in light of the biomedical implication of using physical energies to govern (stem) cell fate. We focus on the feasibility of exploiting atomic force microscopy and hyperspectral imaging to detect signatures of nanomotions and electromagnetic radiation (light), respectively, generated by the stem cells across the specification of their multilineage repertoire. The chance is reported of using these signatures and the diffusive features of physical waves to direct specifically the differentiation program of stem cells in situ, where they already are resident in all the tissues of the human body. We discuss how this strategy may pave the way to a regenerative and precision medicine without the needs for (stem) cell or tissue transplantation. We describe a novel paradigm based upon boosting our inherent ability for self-healing.

Restoring In Vivo-Like Membrane Lipidomics Promotes Exosome Trophic Behavior from Human Placental Mesenchymal Stromal/Stem Cells.

Human mesenchymal stem cells (hMSCs) are an effective tool in regenerative medicine notably for their intrinsic plentiful paracrine activity rather than differentiating properties. The hMSC secretome includes a wide spectrum of regulatory and trophic factors, encompassing several naked molecules as well as different kinds of extracellular vesicles (EVs). Among EVs, exosomes represent an intriguing population, able to shuttle proteins, transcription factors, and genetic materials, with a relevant role in cell-to-cell communication, modulating biological responses in recipient cells. In this context, the extracellular milieu can greatly impact the paracrine activity of stem cells, modifying their metabolism, and the dynamics of vesicle secretion. In the present study, we investigated the effects elicited on exosome patterning by tailored, ad hoc formulated lipid supplementation (Refeed®) in MSCs derived from human fetal membranes (hFM-MSCs). Wound healing experiments revealed that stem cell exposure to exosomes obtained from Refeed®-supplemented hFM-MSCs increased their migratory capability, although the amount of exosomes released after Refeed® supplementation was lower than that yielded from non-supplemented cells. We found that such a decrease was mainly due to a different rate of exosomal exocytosis rather than to an effect of the lipid supplement on the endocytic pathway. Endoplasmic reticulum homeostasis was modified by supplementation, through the upregulation of PKR-like ER kinase (PERK) and inositol-requiring enzyme 1α (IRE1α). Increased expression of these proteins did not lead to stress-induced, unfolded protein response (UPR)-mediated apoptosis, nor did it affect phosphorylation of p38 kinase, suggesting that PERK and IRE1α overexpression was due to augmented metabolic activities mediated by optimization of a cellular feeding network afforded through lipid supplementation. In summary, these results demonstrate how tailored lipid supplementation can successfully modify the paracrine features in hFM-MSCs, impacting both intracellular vesicle trafficking and secreted exosome number and function.

Long-term Intake of Pasta Containing Barley (1-3)Beta-D-Glucan Increases Neovascularization-mediated Cardioprotection through Endothelial Upregulation of Vascular Endothelial Growth Factor and Parkin.

Barley (1-3)ß-D-Glucan (BBG) enhances angiogenesis. Since pasta is very effective in providing a BBG-enriched diet, we hypothesized that the intake of pasta containing 3% BBG (P-BBG) induces neovascularization-mediated cardioprotection. Healthy adult male C57BL/6 mice fed P-BBG (n = 15) or wheat pasta (Control, n = 15) for five-weeks showed normal glucose tolerance and cardiac function. With a food intake similar to the Control, P-BBG mice showed a 109% survival rate (P < 0.01 vs. Control) after cardiac ischemia (30 min)/reperfusion (60 min) injury. Left ventricular (LV) anion superoxide production and infarct size in P-BBG mice were reduced by 62 and 35% (P < 0.0001 vs. Control), respectively. The capillary and arteriolar density of P-BBG hearts were respectively increased by 12 and 18% (P < 0.05 vs. Control). Compared to the Control group, the VEGF expression in P-BBG hearts was increased by 87.7% (P < 0.05); while, the p53 and Parkin expression was significantly increased by 125% and cleaved caspase-3 levels were reduced by 33% in P-BBG mice. In vitro, BBG was required to induce VEGF, p53 and Parkin expression in human umbelical vascular endothelial cells. Moreover, the BBG-induced Parkin expression was not affected by pifithrin-α (10 uM/7days), a p53 inhibitor. In conclusion, long-term dietary supplementation with P-BBG confers post-ischemic cardioprotection through endothelial upregulation of VEGF and Parkin.

Infection of human monocytes by Chlamydia pneumoniae and Chlamydia trachomatis: an in vitro comparative study.

BACKGROUND: An increasing number of studies suggest that chlamydiae can infect immune cells. The altered immune cell function could contribute to the progression of several chronic inflammatory diseases.The aim of this study was to comparatively evaluate Chlamydia pneumoniae (CP) and Chlamydia trachomatis (CT) interactions with in vitro infected human blood monocytes. RESULTS: Fresh isolated monocytes were infected with viable CP and CT elementary bodies and infectivity was evaluated by recultivating disrupted monocytes in permissive epithelial cells.The production of reactive oxygen and nitrogen species was studied in the presence of specific fluorescent probes. Moreover, TNF-α, INF-α, INF-ß and INF-γ gene expression was determined. CT clearance from monocytes was complete at any time points after infection, while CP was able to survive up to 48 hours after infection. When NADPH oxydase or nitric oxide synthase inhibitors were used, CT infectivity in monocytes was restored, even if at low level, and CT recovery's rate was comparable to CP one.CT-infected monocytes produced significantly higher levels of reactive species compared with CP-infected monocytes, at very early time points after infection. In the same meanwhile, TNF-α and INF-γ gene expression was significantly increased in CT-infected monocytes. CONCLUSIONS: Our data confirm that CP, but not CT, is able to survive in infected monocytes up to 48 hours post-infection. The delay in reactive species and cytokines production by CP-infected monocytes seems to be crucial for CP survival.

Radio electric conveyed fields directly reprogram human dermal skin fibroblasts toward cardiac, neuronal, and skeletal muscle-like lineages.

Somatic cells can be directly reprogrammed to alternative differentiated fates without first becoming stem/progenitor cells. Nevertheless, the initial need for viral-mediated gene delivery renders this strategy unsafe in humans. Here, we provide evidence that exposure of human skin fibroblasts to a Radio Electric Asymmetric Conveyer (REAC), an innovative device delivering radio electric conveyed fields at a radiofrequency of 2.4 GHz, afforded remarkable commitment toward cardiac, neuronal, and skeletal muscle lineages. REAC induced the transcription of tissue-restricted genes, including Mef2c, Tbx5, GATA4, Nkx2.5, and prodynorphin for cardiac reprogramming, as well as myoD, and neurogenin 1 for skeletal myogenesis and neurogenesis, respectively. Conversely, REAC treatment elicited a biphasic effect on a number of stemness-related genes, leading to early transcriptional increase of Oct4, Sox2, cMyc, Nanog, and Klf4 within 6-20 h, followed by a downregulation at later times. The REAC action bypassed a persistent reprogramming toward an induced pluripotent stem cell-like state and involved the transcriptional induction of the NADPH oxidase subunit Nox4. Our results show for the first time the feasibility of using a physical stimulus to afford the expression of pluripotentiality in human adult somatic cells up to the attainment of three major target lineages for regenerative medicine.

Rosuvastatin elicits KDR-dependent vasculogenic response of human placental stem cells through PI3K/AKT pathway.

The growth and plasticity of engrafted human mesenchymal stem cells is regulated by external stimuli. Rosuvastatin (RSV) promotes myocardial neovascularization and limits myocardial remodeling in patients with chronic heart failure (CHF). While these non-lipid benefits may in part depend on the activation of stem cells, experimental evidence that RSV directly elicits vasculogenic differentiation of human mesenchymal stem cells is still lacking. We assessed whether RSV may drive a gene program of vascular commitment and the secretion of trophic mediators with antiapoptotic, angiogenic and antifibrotic activities in human mesenchymal stem cells from full-term placentas (FMhMSCs). With real-time RT-PCR, immunofluorescence, chemiluminescence, Western blot analysis, and in vitro vasculogenesis assays, we show that RSV enhanced expression of vascular endothelial growth factor (VEGF), kinase insert domain receptor (KDR), encoding a major VEGF receptor, hepatocyte growth factor (HGF), and platelet-derived growth factor-BB (PDGF-BB) in a time- and dose-dependent manner. GATA-4 and Nkx-2.5 transcription was not affected. RSV enhanced capillary-like formation in vitro, but capillary-embedded FMhMSCs lacked endothelial marker expression, suggesting a role of pericyte-like elements in tube formation. In HUVEC/FMhMSC cocultures, RSV increases PDGFRß expression in FMhMSCs, and enhanced capillary density and organizational efficiency, promoting a long-lasting survival of tubular networks. RSV also activated PI3K-Akt pathway; the vasculogenic effects of the statin were abrogated following PI3K inhibition by LY294002. In conclusion, RSV-induced increase in capillary formation was dependent on VEGF and KDR. RSV promotes the activation of paracrine signals for vascular commitment of FMhMSCs through PI3K-Akt pathway. This observation may pave the way to the use of RSV as a pharmacological enhancer of stem cell potential for cardiovascular cell therapy.

Placental stem cells pre-treated with a hyaluronan mixed ester of butyric and retinoic acid to cure infarcted pig hearts: a multimodal study.

AIMS: Pre-treating placenta-derived human mesenchymal stem cells (FMhMSCs) with a hyaluronan mixed ester of butyric and retinoic acid (HBR) potentiates their reparative capacity in rodent hearts. Our aim was to test FMhMSCs in a large-animal model by employing a novel combination of in vivo and ex vivo analyses. METHODS AND RESULTS: Matched regional quantifications of myocardial function and viability were performed by magnetic resonance imaging (MRI) and positron emission tomography (PET) 4 weeks after myocardial infarction combined with intramyocardial injection of FMhMSCs (n = 7), or HBR-pre-treated FMhMSCs (HBR-FMhMSCs, n = 6), or saline solution (PBS, n = 7). Sham-operated pigs (n = 4) were used as control animals. Despite no differences in the ejection fraction and haemodynamics, regional MRI revealed, in pigs treated with HBR-FMhMSCs compared with the other infarcted groups, a 40% smaller infarct scar size and a significant improvement of the end-systolic wall thickening and circumferential shortening of the infarct border zone. Consistently, PET showed that myocardial perfusion and glucose uptake were, respectively, 35 and 23% higher in the border zone of pigs treated with HBR-FMhMSCs compared with the other infarcted groups. Histology supported in vivo imaging; the delivery of HBR-FMhMSCs significantly enhanced capillary density and decreased fibrous tissue by approximately 68%. Moreover, proteomic analysis of the border zone in the HBR-FMhMSCs group and the FMhMSCs group indicated, respectively, 45 and 30% phenotypic homology with healthy tissue, while this homology was only 26% in the border zone of the PBS group. CONCLUSION: Our results support a more pronounced reparative potential of HBR-pre-treated FMhMSCs in a clinically relevant animal model of infarction and highlight the necessity of using combined diagnostic imaging to avoid underestimations of stem cell therapeutic effects in the heart.

Hyaluronan esters drive Smad gene expression and signaling enhancing cardiogenesis in mouse embryonic and human mesenchymal stem cells.

BACKGROUND: Development of molecules chemically modifying the expression of crucial orchestrator(s) of stem cell commitment may have significant biomedical impact. We have recently developed hyaluronan mixed esters of butyric and retinoic acids (HBR), turning cardiovascular stem cell fate into a high-yield process. The HBR mechanism(s) remain still largely undefined. METHODOLOGY/PRINCIPAL FINDINGS: We show that in both mouse embryonic stem (ES) cells and human mesenchymal stem cells from fetal membranes of term placenta (FMhMSCs), HBR differentially affected the patterning of Smad proteins, one of the major conductors of stem cell cardiogenesis. Real-time RT-PCR and Western blot analyses revealed that in both cell types HBR enhanced gene and protein expression of Smad1,3, and 4, while down-regulating Smad7. HBR acted at the transcriptional level, as shown by nuclear run-off experiments in isolated nuclei. Immunofluorescence analysis indicated that HBR increased the fluorescent staining for Smad1,3, and 4, confirming that the transcriptional action of HBR encompassed the upregulation of the encoded Smad proteins. Chromatin immune precipitation and transcriptional analyses showed that HBR increased the transcription of the cardiogenic gene Nkx-2.5 through Smad4 binding to its own consensus Smad site. Treatment of mouse ES cells and FMhMSCs with HBR led to the concomitant overexpression of both Smad4 and α-sarcomeric actinin. Smad4 silencing by the aid of lentiviral-mediated Smad4 shRNA confirmed a dominant role of Smad4 in HBR-induced cardiogenesis. CONCLUSIONS/SIGNIFICANCE: The use of HBR may pave the way to novel combinatorial strategies of molecular and stem cell therapy based on fine tuning of targeted Smad transciption and signaling leading to a high-throughput of cardiogenesis without the needs of gene transfer technologies.

Hyaluronan mixed esters of butyric and retinoic acid affording myocardial survival and repair without stem cell transplantation.

Possible cardiac repair by adult stem cell transplantation is currently hampered by poor cell viability and delivery efficiency, uncertain differentiating fate in vivo, the needs of ex vivo cell expansion, and consequent delay in transplantation after the onset of heart attack. By the aid of magnetic resonance imaging, positron emission tomography, and immunohistochemistry, we show that injection of a hyaluronan mixed ester of butyric and retinoic acid (HBR) into infarcted rat hearts afforded substantial cardiovascular repair and recovery of myocardial performance. HBR restored cardiac [(18)F]fluorodeoxyglucose uptake and increased capillary density and led to the recruitment of endogenous Stro-1-positive stem cells. A terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay demonstrated that HBR-treated hearts exhibited a decrease in the number of apoptotic cardiomyocytes. In isolated rat cardiomyocytes and Stro-1 stem cells, HBR enhanced the transcription of vascular endothelial growth factor, hepatocyte growth factor, kdr, akt, and pim-1. HBR also increased the secretion of vascular endothelial growth factor and hepatocyte growth factor, suggesting that the mixed ester may have recruited both myocardial and Stro-1 cells also. An increase in capillarogenesis was induced in vitro with medium obtained from HBR-exposed cells. In the infarcted myocardium, HBR injection increased histone H4 acetylation significantly. Acetyl-H4 immunoreactivity increased in rat cardiomyocytes and Stro-1 cells exposed to HBR, compared with untreated cells. In conclusion, efficient cardiac regenerative therapy can be afforded by HBR without the need of stem cell transplantation or vector-mediated gene delivery.

Stem cells and cardiovascular repair: a role for natural and synthetic molecules harboring differentiating and paracrine logics.

Stem cells hold considerable promise for cardiovascular rescue in patients with heart failure due to myocardial infarction or hereditary cardiomyopathies. However, cardiogenesis, one of the earliest and most complex morphogenetic events in the embryo, is only partially exploited at molecular level. The yield of myocardial cells spontaneously derived from human embryonic or adult stem cells is extremely low (usually less than 0.1%). Moreover, it is now evident that secretion of specific growth factors from transplanted stem cells may activate angiogenic, antiapoptotic and antifibrotic paracrine patterning within the recipient heart, playing a major role in tissue repair. Within this context, targeting stem cell fate at the level of gene expression represents a potentially powerful therapeutic approach to afford a high-throughput of cardiovascular lineage commitment and paracrine secretion of "trophic factors". Cell-based phenotypic- and pathway-specific screens of natural and synthetic compounds have provided a number of molecules achieving selective control of stem cell growth and differentiation. Novel hyaluronan mixed esters of butyric and retinoic acids have been recently synthesized, emerging as new tools for manipulation of cardio/vasculogenic gene expression through the modulation of targeted signaling pathways and chromatin-remodeling enzymes. These molecules have coaxed both murine embryonic and human mesenchymal stem cells towards cardiovascular decision and paracrine secretion of bioactive factors, remarkably enhancing the rescuing potential of human stem cells in in vivo animal models of myocardial infarction. These molecules may ultimately provide new insights in stem cell biology and pave the way to novel approaches in tissue engineering and cardiovascular repair.

Hyaluronan mixed esters of butyric and retinoic Acid drive cardiac and endothelial fate in term placenta human mesenchymal stem cells and enhance cardiac repair in infarcted rat hearts.

We have developed a mixed ester of hyaluronan with butyric and retinoic acid (HBR) that acted as a novel cardiogenic/vasculogenic agent in human mesenchymal stem cells isolated from bone marrow, dental pulp, and fetal membranes of term placenta (FMhMSCs). HBR remarkably enhanced vascular endothelial growth factor (VEGF), KDR, and hepatocyte growth factor (HGF) gene expression and the secretion of the angiogenic, mitogenic, and antiapoptotic factors VEGF and HGF, priming stem cell differentiation into endothelial cells. HBR also increased the transcription of the cardiac lineage-promoting genes GATA-4 and Nkx-2.5 and the yield of cardiac markerexpressing cells. These responses were notably more pronounced in FMhMSCs. FMhMSC transplantation into infarcted rat hearts was associated with increased capillary density, normalization of left ventricular function, and significant decrease in scar tissue. Transplantation of HBR-preconditioned FMhM-SCs further enhanced capillary density and the yield of human vWF-expressing cells, additionally decreasing the infarct size. Some engrafted, HBR-pretreated FMhMSCs were also positive for connexin 43 and cardiac troponin I. Thus, the beneficial effects of HBR-exposed FMhMSCs may be mediated by a large supply of angiogenic and antiapoptotic factors, and FMhMSC differentiation into vascular cells. These findings may contribute to further development in cell therapy of heart failure.

Term Amniotic membrane is a high throughput source for multipotent Mesenchymal Stem Cells with the ability to differentiate into endothelial cells in vitro.

BACKGROUND: Term Amniotic membrane (AM) is a very attractive source of Mesenchymal Stem Cells (MSCs) due to the fact that this fetal tissue is usually discarded without ethical conflicts, leading to high efficiency in MSC recovery with no intrusive procedures. Here we confirmed that term AM, as previously reported in the literature, is an abundant source of hMSCs; in particular we further investigated the AM differentiation potential by assessing whether these cells may also be committed to the angiogenic fate. In agreement with the recommendation of the International Society for Cellular Therapy, the mesenchymal cells herein investigated were named Amniotic Membrane-human Mesenchymal Stromal Cells (AM-hMSC). RESULTS: The recovery of hMSCs and their in vitro expansion potential were greater in amniotic membrane than in bone marrow stroma. At flow cytometry analysis AM-hMSCs showed an immunophenotypical profile, i.e., positive for CD105, CD73, CD29, CD44, CD166 and negative for CD14, CD34, CD45, consistent with that reported for bone marrow-derived MSCs. In addition, amniotic membrane-isolated cells underwent in vitro osteogenic (von Kossa stain), adipogenic (Oil Red-O stain), chondrogenic (collagen type II immunohistochemichal detection) and myogenic (RT-PCR MyoD and Myogenin expression as well as desmin immunohistochemical detection) differentiation. In angiogenic experiments, a spontaneous differentiation into endothelial cells was detected by in vitro matrigel assay and this behaviour has been enhanced through Vascular Endothelial Growth Factor (VEGF) induction. According to these findings, VEGF receptor 1 and 2 (FLT-1 and KDR) were basally expressed in AM-hMSCs and the expression of endothelial-specific markers like FLT-1 KDR, ICAM-1 increased after exposure to VEGF together with the occurrence of CD34 and von Willebrand Factor positive cells. CONCLUSION: The current study suggests that AM-hMSCs may emerge as a remarkable tool for the cell therapy of multiple diseased tissues. AM-hMSCs may potentially assist both bone and cartilage repair, nevertheless, due to their angiogenic potential, they may also pave the way for novel approaches in the development of tissue-engineered vascular grafts which are useful when vascularization of ischemic tissues is required.