At the stem of youth and health

Human gingival mesenchymal stem cells retain their growth and immunomodulatory characteristics independent of donor age

Aging has been reported to deteriorate the quantity and quality of mesenchymal stem cells (MSCs), which affect their therapeutic use in regenerative medicine. A dearth of age-related stem cell research further restricts their clinical applications. The present study explores the possibility of using MSCs derived from human gingival tissues (GMSCs) for studying their ex vivo growth characteristics and differentiation potential with respect to donor age. GMSCs displayed decreased in vitro adipogenesis and in vitro and in vivo osteogenesis with age, but in vitro neurogenesis remained unaffected. An increased expression of p53 and SIRT1 with donor age was correlated to their ability of eliminating tumorigenic events through apoptosis or autophagy, respectively. Irrespective of donor age, GMSCs displayed effective immunoregulation and regenerative potential in a mouse model of LPS-induced acute lung injury. Thus, we suggest the potential of GMSCs for designing cell-based immunomodulatory therapeutic approaches and their further extrapolation for acute inflammatory conditions such as acute respiratory distress syndrome and COVID-19.

Engineering the Lymphatic Network: A Solution to Lymphedema

Secondary lymphedema is a life-long disorder characterized by chronic tissue swelling and inflammation that obstruct interstitial fluid circulation and immune cell trafficking. Regenerating lymphatic vasculatures using various strategies represents a promising treatment for lymphedema. Growth factor injection and gene delivery have been developed to stimulate lymphangiogenesis and augment interstitial fluid resorption. Using bioengineered materials as growth factor delivery vehicles allows for a more precisely targeted lymphangiogenic activation within the injured site. The implantation of prevascularized lymphatic tissue also promotes in situ lymphatic capillary network formation. The engineering of larger scale lymphatic tissues, including lymphatic collecting vessels and lymph nodes constructed by bioengineered scaffolds or decellularized animal tissues, offers alternatives to reconnecting damaged lymphatic vessels and restoring lymph circulation. These approaches provide lymphatic vascular grafting materials to reimpose lymphatic continuity across the site of injury, without creating secondary injuries at donor sites. The present work reviews molecular mechanisms mediating lymphatic system development, approaches to promoting lymphatic network regeneration, and strategies for engineering lymphatic tissues, including lymphatic capillaries, collecting vessels, and nodes. Challenges of advanced translational applications are also discussed.

Two mechanisms of cardiac stem cell-mediated cardiomyogenesis in the adult mammalian heart include formation of colonies and cell-in-cell structures

Aims

Because the mechanism of mature cardiomyocyte (CM) development from cardiac stem cells (CSCs) is not fully understood, we explored the involvement of CSCs into two pathways of cardiomyogenesis in adult mammalian heart: (1) via colony formation and (2) by means of intracellular development of CSCs inside CMs followed by the formation of “cell-in-cell structures” (CICSs).

Methods and Results

Using immunostaining and confocal microscopy, we studied the presence of CSC-derived colonies, CICSs and transitory amplifying cells (TACs), released from ruptured CICSs, in a suspension of ex vivo freshly isolated myocardial cells of mammals of different age and species, human including. All subsets of CSCs (c-kit+, Sca-1+ and Isl-1+) were found in mammals of different age. It was shown that c-kit+ and Sca-1+ CSCs produce both colonies and CICSs. However, Isl-1+ CSCs seem to be involved in cardiac growth during first month of age only both through colony formation and CICS generation. In turn, the studies on myocardial cell suspensions of adult C57/bl6N mice, one-year-old bull and 45-year-old woman not only confirmed the involvement of c-kit+ and Sca-1+ CSCs in both mechanisms of cardiomyogenesis, but also showed that Isl-1+ colonies are present in the myocardium of adult mice and rarely in human.

Conclusions

The presence of CSC-derived colonies, CICSs and TACs in all experimental specimens of myocardium proved our previous hypothesis about two pathways that generate new CMs in adult heart. Moreover, we suggest that TACs play a central role in self-renewal of myocardium throughout the lifetime of mammals.

The Light and Shadow of Senescence and Inflammation in Cardiovascular Pathology and Regenerative Medicine

Recent epidemiologic studies evidence a dramatic increase of cardiovascular diseases, especially associated with the aging of the world population. During aging, the progressive impairment of the cardiovascular functions results from the compromised tissue abilities to protect the heart against stress. At the molecular level, in fact, a gradual weakening of the cellular processes regulating cardiovascular homeostasis occurs in aging cells. Atherosclerosis and heart failure are particularly correlated with aging-related cardiovascular senescence, that is, the inability of cells to progress in the mitotic program until completion of cytokinesis. In this review, we explore the intrinsic and extrinsic causes of cellular senescence and their role in the onset of these cardiovascular pathologies. Additionally, we dissect the effects of aging on the cardiac endogenous and exogenous reservoirs of stem cells. Finally, we offer an overview on the strategies of regenerative medicine that have been advanced in the quest for heart rejuvenation.

Mucoadhesive solid lipid microparticles for controlled release of a corticosteroid in the chronic obstructive pulmonary disease treatment

Aim: Therapeutic efficacy of pulmonary diseases is often limited and drug delivery systems offer new solutions to clinical problems. Solid lipid microparticles (SLMs) are suggested as systems for the delivery of therapeutics to the lung as, because of their size, they are able to deposit into secondary bronchi. Materials & methods: Here, we describe two novel different SLMs using chitosan and alginate such as mucoadhesive polymers and we also studied their biocompatibility and their effectiveness compared with the free drug in controlling senescence and inflammatory processes in cigarette smoke extracts. Results: Data reported show that fluticasone propionate (FP)-loaded SLMs are more effective than FP alone in controlling oxidative stress. Conclusion: The therapeutic approach using FP-loaded microparticles could be a promising strategy for the treatment of the chronic inflammatory pulmonary diseases.

Polyaspartamide-Based Nanoparticles Loaded with Fluticasone Propionate and the In Vitro Evaluation towards Cigarette Smoke Effects

This paper describes the evaluation of polymeric nanoparticles (NPs) as a potential carrier for lung administration of fluticasone propionate (FP). The chosen polymeric material to produce NPs was a copolymer based on α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) whose backbone was derivatised with different molecules, such as poly(lactic acid) (PLA) and polyethylenglycol (PEG). The chosen method to produce NPs from PHEA-PLA-PEG₂₀₀₀ was the method based on high-pressure homogenization and subsequent solvent evaporation by adding Pluronic F68 during the process and trehalose before lyophilisation. Obtained colloidal FP-loaded NPs showed a slightly negative surface charge and nanometric dimensions that are maintained after storage for one year at −20 °C and 5 °C. The FP loading was about 2.9 wt % and the drug was slowly released in simulated lung fluid. Moreover, the obtained NPs, containing the drug or not, were biocompatible and did not induce cell necrosis and cell apoptosis on bronchial epithelial cells (16-HBE). Further in vitro testing on cigarette smoke extract (CSE)-stimulated 16-HBE revealed that FP-loaded NPs were able to reduce the survivin expression, while either free FP or empty NPs were not able to significantly reduce this effect.

Cardiac Cell Senescence and Redox Signaling

Aging is characterized by a progressive loss of the ability of the organism to cope with stressors and to repair tissue damage. As a result, chronic diseases, including cardiovascular disease, increase their prevalence with aging, underlining the existence of common mechanisms that lead to frailty and age-related diseases. In this frame, the progressive decline of the homeostatic and reparative function of primitive cells has been hypothesized to play a major role in the evolution of cardiac pathology to heart failure. Although initially it was believed that reactive oxygen species (ROS) were produced in an unregulated manner as a byproduct of cellular metabolism, causing macromolecular damage and aging, accumulating evidence indicate the major role played by redox signaling in physiology. Aim of this review is to critically revise evidence linking ROS to cell senescence and aging and to provide evidence of the primary role played by redox signaling, with a particular emphasis on the multifunctional protein APE1/Ref in stem cell biology. Finally, we will discuss evidence supporting the role of redox signaling in cardiovascular cells.

Carbocysteine counteracts the effects of cigarette smoke on cell growth and on the SIRT1/FoxO3 axis in bronchial epithelial cells

BACKGROUND

Cigarette smoke may accelerate cellular senescence by increasing oxidative stress. Altered proliferation and altered expression of anti-aging factors, including SIRT1 and FoxO3, characterise cellular senescence. The effects of carbocysteine on the SIRT1/FoxO3 axis and on downstream molecular mechanisms in human bronchial epithelial cells exposed to cigarette smoke are largely unknown.

AIMS

Aim of this study was to explore whether carbocysteine modulated SIRT1/FoxO3 axis, and downstream molecular mechanisms associated to cellular senescence, in a bronchial epithelial cell line (16-HBE) exposed to cigarette smoke.

METHODS

16HBE cells were stimulated with/without cigarette smoke extracts (CSE) and carbocysteine. Flow cytometry and clonogenic assay were used to assess cell proliferation; western blot analysis was used for assessing nuclear expression of SIRT1 and FoxO3. The nuclear co-localization of SIRT1 and FoxO3 was assessed by fluorescence microscopy. Beta galactosidase (a senescence marker) and SIRT1 activity were assessed by specific staining and colorimetric assays, respectively. ChiP Assay and flow cytometry were used for assessing survivin gene regulation and protein expression, respectively.

RESULTS

CSE decreased cell proliferation, the nuclear expression of SIRT1 and FoxO3 and increased beta galactosidase staining. CSE, reduced SIRT1 activity and FoxO3 localization on survivin promoter thus increasing survivin expression. In CSE stimulated bronchial epithelial cells carbocysteine reverted these phenomena by increasing cell proliferation, and SIRT1 and FoxO3 nuclear expression, and by reducing beta galactosidase staining and survivin expression.

CONCLUSIONS

The study shows for the first time that carbocysteine may revert some senescence processes induced by oxidative stress due to cigarette smoke exposure.

Changes in mitotic reorientation and Wnt/AR signaling in rat prostate epithelial cells exposed to subchronic testosterone

The aim of the present study was to investigate the changes in mitotic reorientation and relative differential gene expression in rat prostate epithelial cells following long-term exposure to testosterone propionate (TP). Sprague-Dawley rats were randomly divided into two groups as follows: TP group, which received 3.7 mg/kg/day TP for 30 days (n=10); and control group, in which rats were injected with olive oil (n=10). Microscopic analysis of the prostate tissue was performed by immunohistochemical analysis and hematoxylin and eosin staining. Differential gene expression analysis was performed via gene microarray, and a total of five genes (Dkk3, Ran, Fas, Tgm4 and Wnt2) were selected and their expression levels were verified using reverse transcription-polymerase chain reaction. For rats treated with TP, mitosis was significantly reoriented, becoming parallel to the basement membrane. By contrast, in the control group cells mitotic orientation remained perpendicular to the basement membrane. Genes such as Ran and Tgm4 in the androgen receptor (AR) signaling pathway and Wnt2 in the Wnt signaling pathway, were upregulated following treatment with TP. Conversely, the Dkk3 and Fas genes were downregulated following treatment with TP. In conclusion, mitotic orientation of prostate epithelial cells was altered following long-term administration of TP. Wnt and AR signaling pathways influenced cell proliferation and may have participated in the mitotic orientation change.

Ex vivo molecular rejuvenation improves the therapeutic activity of senescent human cardiac stem cells in a mouse model of myocardial infarction

Cardiac stem cells (CSC) from explanted decompensated hearts (E-CSC) are, with respect to those obtained from healthy donors (D-CSC), senescent and functionally impaired. We aimed to identify alterations in signaling pathways that are associated with CSC senescence. Additionally, we investigated if pharmacological modulation of altered pathways can reduce CSC senescence in vitro and enhance their reparative ability in vivo. Measurement of secreted factors showed that E-CSC release larger amounts of proinflammatory cytokine IL1β compared with D-CSC. Using blocking antibodies, we verified that IL1β hampers the paracrine protective action of E-CSC on cardiomyocyte viability. IL1β acts intracranially inducing IKKβ signaling, a mechanism that via nuclear factor-κB upregulates the expression of IL1β itself. Moreover, E-CSC show reduced levels of AMP protein kinase (AMPK) activating phosphorylation. This latter event, together with enhanced IKKβ signaling, increases TORC1 activity, thereby impairing the autophagic flux and inhibiting the phosphorylation of Akt and cAMP response element-binding protein. The combined use of rapamycin and resveratrol enhanced AMPK, thereby restoring downstream signaling and reducing IL1β secretion. These molecular corrections reduced E-CSC senescence, re-establishing their protective activity on cardiomyocytes. Moreover ex vivo treatment with rapamycin and resveratrol improved E-CSC capacity to induce cardiac repair upon injection in the mouse infarcted heart, leading to reduced cardiomyocyte senescence and apoptosis and increased abundance of endogenous c-Kit(+) CSC in the peri-infarct area. Molecular rejuvenation of patient-derived CSC by short pharmacologic conditioning boosts their in vivo reparative abilities. This approach might prove useful for refinement of CSC-based therapies.

Fabrication of tissue-engineered vascular grafts with stem cells and stem cell-derived vascular cells

INTRODUCTION

Cardiovascular disease is the leading cause of mortality worldwide. Current surgical treatments for cardiovascular disease include vascular bypass grafting and replacement with autologous blood vessels or synthetic vascular grafts. However, there is a call for better alternative biological grafts.

AREAS COVERED

Tissue-engineered vascular grafts (TEVGs) are promising novel alternatives to replace diseased vessels. However, obtaining enough functional and clinically usable vascular cells for fabrication of TEVGs remains a major challenge. New findings in adult stem cells and recent advances in pluripotent stem cells have opened a new avenue for stem cell-based vascular engineering. In this review, recent advances on stem cell sourcing for TEVGs including the use of adult stem cells and pluripotent stem cells and advantages, disadvantages, and possible future implementations of different types of stem cells will be discussed. In addition, current strategies used during the fabrication of TEVGs will be highlighted.

EXPERT OPINION

The application of patient-specific TEVGs constructed with vascular cells derived from immune-compatible stem cells possesses huge clinical potential. Advances in lineage-specific differentiation approaches and innovative vascular engineering strategies will promote the vascular regeneration field from bench to bedside.

DNA Damage, DNA Repair, Aging, and Neurodegeneration

Aging in mammals is accompanied by a progressive atrophy of tissues and organs, and stochastic damage accumulation to the macromolecules DNA, RNA, proteins, and lipids. The sequence of the human genome represents our genetic blueprint, and accumulating evidence suggests that loss of genomic maintenance may causally contribute to aging. Distinct evidence for a role of imperfect DNA repair in aging is that several premature aging syndromes have underlying genetic DNA repair defects. Accumulation of DNA damage may be particularly prevalent in the central nervous system owing to the low DNA repair capacity in postmitotic brain tissue. It is generally believed that the cumulative effects of the deleterious changes that occur in aging, mostly after the reproductive phase, contribute to species-specific rates of aging. In addition to nuclear DNA damage contributions to aging, there is also abundant evidence for a causative link between mitochondrial DNA damage and the major phenotypes associated with aging. Understanding the mechanistic basis for the association of DNA damage and DNA repair with aging and age-related diseases, such as neurodegeneration, would give insight into contravening age-related diseases and promoting a healthy life span.

Unraveling the non-senescence phenomenon in Hydra

Unlike other metazoans, Hydra does not experience the distinctive rise in mortality with age known as senescence, which results from an increasing imbalance between cell damage and cell repair. We propose that the Hydra controls damage accumulation mainly through damage-dependent cell selection and cell sloughing. We examine our hypothesis with a model that combines cellular damage with stem cell renewal, differentiation, and elimination. The Hydra individual can be seen as a large single pool of three types of stem cells with some features of differentiated cells. This large stem cell community prevents "cellular damage drift," which is inevitable in complex conglomerate (differentiated) metazoans with numerous and generally isolated pools of stem cells. The process of cellular damage drift is based on changes in the distribution of damage among cells due to random events, and is thus similar to Muller's ratchet in asexual populations. Events in the model that are sources of randomness include budding, cellular death, and cellular damage and repair. Our results suggest that non-senescence is possible only in simple Hydra-like organisms which have a high proportion and number of stem cells, continuous cell divisions, an effective cell selection mechanism, and stem cells with the ability to undertake some roles of differentiated cells.

Investigation of early cell-surface interactions of human mesenchymal stem cells on nanopatterned β-type titanium-niobium alloy surfaces

Multi-potent adult mesenchymal stem cells (MSCs) derived from bone marrow have therapeutic potential for bone diseases and regenerative medicine. However, an intrinsic heterogeneity in their phenotype, which in turn results in various differentiation potentials, makes it difficult to predict the response of these cells. The aim of this study is to investigate initial cell-surface interactions of human MSCs on modified titanium alloys. Gold nanoparticles deposited on β-type Ti-40Nb alloys by block copolymer micelle nanolithography served as nanotopographical cues as well as specific binding sites for the immobilization of thiolated peptides present in several extracellular matrix proteins. MSC heterogeneity persists on polished and nanopatterned Ti-40Nb samples. However, cell heterogeneity and donor variability decreased upon functionalization of the gold nanoparticles with cyclic RGD peptides. In particular, the number of large cells significantly decreased after 24 h owing to the arrangement of cell anchorage sites, rather than peptide specificity. However, the size and number of integrin-mediated adhesion clusters increased in the presence of the integrin-binding peptide (cRGDfK) compared with the control peptide (cRADfK). These results suggest that the use of integrin ligands in defined patterns could improve MSC-material interactions, not only by regulating cell adhesion locally, but also by reducing population heterogeneity.

Caloric restriction and aging stem cells: the stick and the carrot?

Adult tissue stem cells have the ability to adjust to environmental changes and affect also the proliferation of neighboring cells, with important consequences on tissue maintenance and regeneration. Stem cell renewal and proliferation is strongly regulated during aging of the organism. Caloric restriction is the most powerful anti-aging strategy conserved throughout evolution in the animal kingdom. Recent studies relate the properties of caloric restriction to its ability in reprogramming stem-like cell states and in prolonging the capacity of stem cells to self-renew, proliferate, differentiate, and replace cells in several adult tissues. However this general paradigm presents with exceptions. The scope of this review is to highlight how caloric restriction impacts on diverse stem cell compartments and, by doing so, might differentially delay aging in the tissues of lower and higher organisms.

Cardiac stem cell senescence

Cellular senescence processes affecting tissue resident stem cells are considered, at present, an hallmark of both aging and age-related pathologies. Therefore it is mandatory to address this problem with adequate techniques that could highlight the molecular alterations associated with this complex cellular response to stressors. Here we describe methods to characterize cardiac stem cell (CSC) senescence from a molecular and functional standpoint.

Stem cell sources for vascular tissue engineering and regeneration

This review focuses on the stem cell sources with the potential to be used in vascular tissue engineering and to promote vascular regeneration. The first clinical studies using tissue-engineered vascular grafts are already under way, supporting the potential of this technology in the treatment of cardiovascular and other diseases. Despite progress in engineering biomaterials with the appropriate mechanical properties and biological cues as well as bioreactors for generating the correct tissue microenvironment, the source of cells that make up the vascular tissues remains a major challenge for tissue engineers and physicians. Mature cells from the tissue of origin may be difficult to obtain and suffer from limited proliferative capacity, which may further decline as a function of donor age. On the other hand, multipotent and pluripotent stem cells have great potential to provide large numbers of autologous cells with a great differentiation capacity. Here, we discuss the adult multipotent as well as embryonic and induced pluripotent stem cells, their differentiation potential toward vascular lineages, and their use in engineering functional and implantable vascular tissues. We also discuss the associated challenges that need to be addressed in order to facilitate the transition of this technology from the bench to the bedside.

Near-to-perfect homeostasis: examples of universal aging rule which germline evades

Aging is considered to be a progressive decline in an organism's functioning over time and is almost universal throughout the living world. Currently, many different aging mechanisms have been reported at all levels of biological organization, with a variety of biochemical, metabolic, and genetic pathways involved. Some of these mechanisms are common across species, and others work different, but each of them is constitutive. This review describes the common characteristics of the aging processes, which are consistent changes over time that involve either the accumulation or depletion of particular system components. These accumulations and depletions may result from imperfect homeostasis, which is the incomplete compensation of a particular biological process with another process evolved to compensate it. In accordance with disposable-soma theory, this imperfection in homeostasis may originate as a function of cell differentiation as early as in yeasts. It may result either from antagonistic pleiotropy mechanisms, or be simply negligible as a subject of natural selection if an adverse effect of the accumulation phenotypically manifests in organism's post-reproductive age. If this phenomenon holds true for many different functions it would lead to the occurrence of a wide variety of aging mechanisms, some of which are common among species, while others unique, because aging is the inherent property of most biological processes that have not yet evolved to be perfectly in balance. Examples of imperfect homeostasis mechanisms of aging, the ways in which germ line escapes from them, and the possibilities of anti-aging treatment are discussed in this review.

Empowering adult stem cells for myocardial regeneration

Treatment strategies for heart failure remain a high priority for ongoing research due to the profound unmet need in clinical disease coupled with lack of significant translational progress. The underlying issue is the same whether the cause is acute damage, chronic stress from disease, or aging: progressive loss of functional cardiomyocytes and diminished hemodynamic output. To stave off cardiomyocyte losses, a number of strategic approaches have been embraced in recent years involving both molecular and cellular approaches to augment myocardial structure and performance. Resultant excitement surrounding regenerative medicine in the heart has been tempered by realizations that reparative processes in the heart are insufficient to restore damaged myocardium to normal functional capacity and that cellular cardiomyoplasty is hampered by poor survival, proliferation, engraftment, and differentiation of the donated population. To overcome these limitations, a combination of molecular and cellular approaches must be adopted involving use of genetic engineering to enhance resistance to cell death and increase regenerative capacity. This review highlights biological properties of approached to potentiate stem cell-mediated regeneration to promote enhanced myocardial regeneration, persistence of donated cells, and long-lasting tissue repair. Optimizing cell delivery and harnessing the power of survival signaling cascades for ex vivo genetic modification of stem cells before reintroduction into the patient will be critical to enhance the efficacy of cellular cardiomyoplasty. Once this goal is achieved, then cell-based therapy has great promise for treatment of heart failure to combat the loss of cardiac structure and function associated with acute damage, chronic disease, or aging.

Stem cell senescence and regenerative paradigms

The term "cellular senescence" denotes a cellular response to several stressors that results in irreversible growth arrest, alterations of the gene expression profile, epigenetic modifications, and an altered secretome, all of which eventually impair the reparative properties of primitive cells, adding a layer of complexity to the field of regenerative medicine. The purpose of this review is to illustrate how cellular senescence could affect tissue repair and to propose interventions that aim at interfering with it.