Stressed stem cells: Temperature response in aged mesenchymal stem cells

Comparison of therapeutic effects of mesenchymal stem cells derived from superficial and deep subcutaneous adipose tissues

BACKGROUND

Fibrosis is a common histological feature in the process from chronic organ injury to organ failure. Chronic tissue injury causes inflammatory cell infiltration into the injured tissue. The persistence of this inflammatory cell infiltration leads to fibrosis and organ failure. Adipose-derived mesenchymal stem cells (ASCs) have received much attention as a regenerative therapeutic tool to prevent progression from organ injury to failure. Subcutaneous abdominal adipose tissue is divided into superficial and deep layers by a superficial fascia. Adipose tissue easily collected by liposuction is usually obtained from a deep layer, so ASCs derived from a deep layer are generally used for regenerative medicine. However, no research has been conducted to investigate differences in the therapeutic effects of ASCs from the superficial and deep layers (Sup-ASCs and Deep-ASCs, respectively). Therefore, we compared the therapeutic potencies of Sup-ASCs and Deep-ASCs.

METHODS

ASCs were isolated from superficial and deep subcutaneous abdominal adipose tissues collected from patients who underwent breast reconstruction. We first compared cell characteristics, such as morphology, cell proliferation, cell surface markers, adipogenic and osteogenic differentiation, cell senescence markers, and expression of coagulation and anticoagulant factors between Sup-ASCs and Deep-ASCs. Furthermore, we compared their ability to promote polarization of M2 macrophages and to inhibit transforming growth factor (TGF)-β/Smad signaling using THP-1 cells and TGF-β1 stimulated HK-2 cells incubated with conditioned media from Sup-ASCs or Deep-ASCs. In in vivo experiments, after renal ischemia-reperfusion injury (IRI) procedure, Sup-ASCs or Deep-ASCs were injected through the abdominal aorta. At 21 days post-injection, the rats were sacrificed and their left kidneys were collected to evaluate fibrosis. Finally, we performed RNA-sequencing analysis of Sup-ASCs and Deep-ASCs.

RESULTS

Sup-ASCs had greater proliferation and adipogenic differentiation compared with Deep-ASCs, whereas both ASC types had similar morphology, cell surface markers, senescence markers, and expression of coagulation and anticoagulant factors. Conditioned media from Sup-ASCs and Deep-ASCs equally promoted polarization of M2 macrophages and suppressed TGF-β/Smad signaling. Moreover, administration of Sup-ASCs and Deep-ASCs equally ameliorated renal fibrosis induced by IRI in rats. RNA-sequencing analysis revealed no significant difference in the expression of genes involved in anti-inflammatory and anti-fibrotic effects between Sup-ASCs and Deep-ASCs.

CONCLUSIONS

These results indicate that both Sup-ASCs and Deep-ASCs can be used effectively and safely as an intravascular ASC therapy for organ injury.

From Vial to Vein: Crucial Gaps in Mesenchymal Stromal Cell Clinical Trial Reporting

Retrospective analysis of clinical trial outcomes is a vital exercise to facilitate efficient translation of cellular therapies. These analyses are particularly important for mesenchymal stem/stromal cell (MSC) products. The exquisite responsiveness of MSCs, which makes them attractive candidates for immunotherapies, is a double-edged sword; MSC clinical trials result in inconsistent outcomes that may correlate with underlying patient biology or procedural differences at trial sites. Here we review 45 North American MSC clinical trial results published between 2015 and 2021 to assess whether these reports provide sufficient information for retrospective analysis. Trial reports routinely specify the MSC tissue source, autologous or allogeneic origin and administration route. However, most methodological aspects related to cell preparation and handling immediately prior to administration are under-reported. Clinical trial reports inconsistently provide information about cryopreservation media composition, delivery vehicle, post-thaw time and storage until administration, duration of infusion, and pre-administration viability or potency assessments. In addition, there appears to be significant variability in how cell products are formulated, handled or assessed between trials. The apparent gaps in reporting, combined with high process variability, are not sufficient for retrospective analyses that could potentially identify optimal cell preparation and handling protocols that correlate with successful intra- and inter-trial outcomes. The substantial preclinical data demonstrating that cell handling affects MSC potency highlights the need for more comprehensive clinical trial reporting of MSC conditions from expansion through delivery to support development of globally standardized protocols to efficiently advance MSCs as commercial products.

Human Amnion Epithelial Cells: A Potential Cell Source for Pulp Regeneration?

The aim of this study was to analyze the suitability of pluripotent stem cells derived from the amnion (hAECs) as a potential cell source for revitalization in vitro. hAECs were isolated from human placentas, and dental pulp stem cells (hDPSCs) and dentin matrix proteins (eDMPs) were obtained from human teeth. Both hAECs and hDPSCs were cultured with 10% FBS, eDMPs and an osteogenic differentiation medium (StemPro). Viability was assessed by MTT and cell adherence to dentin was evaluated by scanning electron microscopy. Furthermore, the expression of mineralization-, odontogenic differentiation- and epithelial–mesenchymal transition-associated genes was analyzed by quantitative real-time PCR, and mineralization was evaluated through Alizarin Red staining. The viability of hAECs was significantly lower compared with hDPSCs in all groups and at all time points. Both hAECs and hDPSCs adhered to dentin and were homogeneously distributed. The regulation of odontoblast differentiation- and mineralization-associated genes showed the lack of transition of hAECs into an odontoblastic phenotype; however, genes associated with epithelial–mesenchymal transition were significantly upregulated in hAECs. hAECs showed small amounts of calcium deposition after osteogenic differentiation with StemPro. Pluripotent hAECs adhere on dentin and possess the capacity to mineralize. However, they presented an unfavorable proliferation behavior and failed to undergo odontoblastic transition.

Heat Shock Proteins and their Protective Roles in Stem Cell Biology

Stem cells (SCs) are discovered long back but the idea that SCs possess therapeutic potential came up just a few decades back. In a past decade stem cell therapy is highly emerged and displayed tremendous potential for the treatment of a wide range of diseases and disorders such as blindness and vision impairment, type I diabetes, infertility, HIV, etc. SCs are very susceptible to destruction after transplantation into the host because of the inability to sustain elevated stress conditions inside the damaged tissue/organ. Heat shock proteins (HSPs) are molecular chaperones/stress proteins expressed in response to stress (elevated temperature, harmful chemicals, ischemia, viruses, etc) inside a living cell. HSPs protect the cell from damage by assisting in the proper folding of cellular proteins. This review briefly summarises different types of HSPs, their classification, cellular functions as well as the role of HSPs in regulating SC self-renewal and survival in the transplanted host. Applications of HSP modulated SCs in regenerative medicine and for the treatment of ischemic heart disease, myocardial infarction (MI), osteoarthritis, ischemic stroke, spinocerebellar ataxia type 3 (SCA3), leukemia, hepatic ischemia-reperfusion injury, Graft-versus-host disease (GVHD) and Parkinson's disease (PD) are discussed. In order to provide potential insights in understanding molecular mechanisms related to SCs in vertebrates, correlations between HSPs and SCs in cnidarians and planarians are also reviewed. There is a need to advance research in order to validate the use of HSPs for SC therapy and establish effective treatment strategies.

Bronchopulmonary dysplasia: Pathophysiology and potential anti-inflammatory therapies

Inflammation of the preterm lungs is key to the pathogenesis of bronchopulmonary dysplasia (BPD), whether it arises as a consequence of intrauterine inflammation or postnatal respiratory management. This review explores steroidal and non-steroidal therapies for reducing neonatal pulmonary inflammation, aimed at treating or preventing BPD.

Aging of mesenchymal stem cells: Implication in regenerative medicine

Multipotent mesenchymal stem cells (MSCs) represent a great candidate for various clinical applications including regenerative medicine. However, aging both in vivo and in vitro can significantly compromise MSC characteristics and performance. This paper highlights current thoughts on senescence-induced damage to MSCs that should be considered prior to their use for regeneration of different cells, tissues or organs.

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Multipotent mesenchymal stem cells give rise to different cell lineages of mesodermal origin.

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Mesenchymal stem cells can undergo aging process during extensive in-vitro expansion.

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Senescence, both in vivo and in vitro, damages the regenerative and therapeutic potential of mesenchymal stem cells.

Tissue regeneration: Impact of sleep on stem cell regenerative capacity

The circadian rhythm orchestrates many cellular functions, such as cell division, cell migration, metabolism and numerous intracellular biological processes. The physiological changes during sleep are believed to promote a suitable microenvironment for stem cells to proliferate, migrate and differentiate. These effects are mediated either directly by circadian clock genes or indirectly via hormones and cytokines. Hormones, such as melatonin and cortisol, are secreted in response to neural optic signals and act in harmony to regulate many biological functions during sleep. Herein, we correlate the effects of the main circadian genes on the expression of certain stem cell genes responsible for the regeneration of different tissues, including bone, cartilage, skin, and intestine. We also review the effects of different hormones and cytokines on stem cell activation or suppression and their relationship to the day/night cycle. The correlation of circadian rhythm with tissue regeneration could have implications in understanding the biology of sleep and tissue regeneration and in enhancing the efficacy and timing of surgical procedures.

Glioma progression through the prism of heat shock protein mediated extracellular matrix remodeling and epithelial to mesenchymal transition

Glial tumor is one of the intrinsic brain tumors with high migratory and infiltrative potential. This essentially contributes to the overall poor prognosis by circumvention of conventional treatment regimen in glioma. The underlying mechanism in gliomagenesis is bestowed by two processes- Extracellular matrix (ECM) Remodeling and Epithelial to mesenchymal transition (EMT). Heat Shock Family of proteins (HSPs), commonly known as "molecular chaperons" are documented to be upregulated in glioma. A positive correlation also exists between elevated expression of HSPs and invasive capacity of glial tumor. HSPs overexpression leads to mutational changes in glioma, which ultimately drive cells towards EMT, ECM modification, malignancy and invasion. Differential expression of HSPs - a factor providing cytoprotection to glioma cells, also contributes towards its radioresistance /chemoresistance. Various evidences also display upregulation of EMT and ECM markers by various heat shock inducing proteins e.g. HSF-1. The aim of this review is to study in detail the role of HSPs in EMT and ECM leading to radioresistance/chemoresistance of glioma cells. The existing treatment regimen for glioma could be enhanced by targeting HSPs through immunotherapy, miRNA and exosome mediated strategies. This could be envisaged by better understanding of molecular mechanisms underlying glial tumorigenesis in relation to EMT and ECM remodeling under HSPs influence. Our review might showcase fresh potential for the development of next generation therapeutics for effective glioma management.

Proteomic profiling of mitochondria: what does it tell us about the ageing brain?

Mitochondrial dysfunction is evident in numerous neurodegenerative and age-related disorders. It has also been linked to cellular ageing, however our current understanding of the mitochondrial changes that occur are unclear. Functional studies have made some progress reporting reduced respiration, dynamic structural modifications and loss of membrane potential, though there are conflicts within these findings. Proteomic analyses, together with functional studies, are required in order to profile the mitochondrial changes that occur with age and can contribute to unravelling the complexity of the ageing phenotype. The emergence of improved protein separation techniques, combined with mass spectrometry analyses has allowed the identification of age and cell-type specific mitochondrial changes in energy metabolism, antioxidants, fusion and fission machinery, chaperones, membrane proteins and biosynthesis pathways. Here, we identify and review recent data from the analyses of mitochondria from rodent brains. It is expected that knowledge gained from understanding age-related mitochondrial changes of the brain should lead to improved biomarkers of normal ageing and also age-related disease progression.

The 6-chromanol derivate SUL-109 enables prolonged hypothermic storage of adipose tissue-derived stem cells

Encouraging advances in cell therapy research with adipose derived stem cells (ASC) require an effective short-term preservation method that provides time for quality control and transport of cells from their manufacturing facility to their clinical destination. Hypothermic storage of cells in their specific growth media offers an alternative and simple preservation method to liquid nitrogen cryopreservation or commercial preservation fluids for short-term storage and transport. However, accumulation of cell damage during hypothermia may result in cell injury and death upon rewarming through the production of excess reactive oxygen species (ROS). Here, the ability of the cell culture medium additive SUL-109, a modified 6-chromanol, to protect ASC from hypothermia and rewarming damage is examined. SUL-109 conveys protective effects against cold-induced damage in ASC as is observed by preservation of cell viability, adhesion properties and growth potential. SUL-109 does not reduce the multilineage differentiation capacity of ASC. SUL-109 conveys its protection against hypothermic damage by the preservation of the mitochondrial membrane potential through the activation of mitochondrial membrane complexes I and IV, and increases maximal oxygen consumption in FCCP uncoupled mitochondria. Consequently, SUL-109 alleviates mitochondrial ROS production and preserves ATP production. In summary, here we describe the generation of a single molecule cell preservation agent that protects ASC from hypothermic damage associated with short-term cell preservation that does not affect the differentiation capacity of ASC.

Recombinant HSP70 and mild heat shock stimulate growth of aged mesenchymal stem cells

Heat shock proteins including the major stress protein HSP70 support intracellular homeostasis and prevent protein damage after a temperature increase and other stressful environmental stimuli, as well as during aging. We have shown earlier that prolonged administration of recombinant human HSP70 to mice exhibiting Alzheimer's-like neurodegeneration as well as during sepsis reduces the clinical manifestations of these pathologies. Herein, we studied the action of recombinant human HSP70 on young and aged mouse mesenchymal stem cells (MSCs) in culture. The results obtained indicate that HSP70 at concentrations of 2 μg/ml and higher significantly stimulates growth of aged but not young MSCs. A similar effect is produced by application of a mild heat shock (42 °C 5 min) to the cells. Importantly, responses of young and aged MSCs to heat shock treatment of various durations differed drastically, and aged MSCs were significantly more sensitive to higher heat stress exposures than the young cells. Western blotting and protein labeling experiments demonstrated that neither mild heat shock nor exogenous HSP70 administration resulted in significant endogenous HSP70 induction in young and aged MSCs, whereas mild heat shock increased HSC70 levels in aged MSCs. The results of this study suggest that the administration of exogenous HSP70 and the application of mild heat stress may produce a certain "rejuvenating" effect on MSCs and possibly other cell types in vivo, and these interventions may potentially be used for life extension by delaying various manifestations of aging at the molecular and cellular level.

Cardiosphere-derived cells from pediatric end-stage heart failure patients have enhanced functional activity due to the heat shock response regulating the secretome

We have demonstrated that human neonatal cardiosphere-derived cells (CDCs) derived from the young are more regenerative due to their robust secretome. However, it is unclear how the decompensated pediatric heart impacts the functional activity of their CDCs. Our aim was to characterize the potency of pediatric CDCs derived from normal functioning myocardium of control heart disease (CHD) patients to those generated from age-matched end stage heart failure (ESHF) patients and to determine the mechanisms involved. ESHF-derived CDCs contained a higher number of c-kit(+) , Islet-1(+) , and Sca-1(+) cells. When transplanted into an infarcted rodent model, ESHF-derived CDCs significantly demonstrated higher restoration of ventricular function, prevented adverse remodeling, and enhanced angiogenesis when compared with CHD patients. The superior functional recovery of the ESHF-derived CDCs was mediated in part by increased SDF-1α and VEGF-A secretion resulting in augmented recruitment of endogenous stem cells and proliferation of cardiomyocytes. We determined the mechanism is due to the secretome directed by the heat shock response (HSR), which is supported by three lines of evidence. First, gain of function studies demonstrated that increased HSR induced the lower functioning CHD-derived CDCs to significantly restore myocardial function. Second, loss-of function studies targeting the HSR impaired the ability of the ESHF-derived CDCs to functionally recover the injured myocardium. Finally, the native ESHF myocardium had an increased number of c-kit(+) cardiac stem cells. These findings suggest that the HSR enhances the functional activity of ESHF-derived CDCs by increasing their secretome activity, notably SDF-1α and VEGF-A.

Equine Metabolic Syndrome Affects Viability, Senescence, and Stress Factors of Equine Adipose-Derived Mesenchymal Stromal Stem Cells: New Insight into EqASCs Isolated from EMS Horses in the Context of Their Aging

Currently, equine metabolic syndrome (EMS), an endocrine disease linked to insulin resistance, affects an increasing number of horses. However, little is known about the effect of EMS on mesenchymal stem cells that reside in adipose tissue (ASC). Thus it is crucial to evaluate the viability and growth kinetics of these cells, particularly in terms of their application in regenerative medicine. In this study, we investigated the proliferative capacity, morphological features, and accumulation of oxidative stress factors in mesenchymal stem cells isolated from healthy animals (ASCN) and horses suffering from EMS (ASCEMS). ASCEMS displayed senescent phenotype associated with β-galactosidase accumulation, enlarged cell bodies and nuclei, increased apoptosis, and reduced heterochromatin architecture. Moreover, we observed increased amounts of nitric oxide (NO) and reactive oxygen species (ROS) in these cells, accompanied by reduced superoxide dismutase (SOD) activity. We also found in ASCEMS an elevated number of impaired mitochondria, characterized by membrane raptures, disarrayed cristae, and vacuole formation. Our results suggest that the toxic compounds, accumulating in the mitochondria under oxidative stress, lead to alternations in their morphology and may be partially responsible for the senescent phenotype and decreased proliferation potential of ASCEMS.

Effect of mild heat stress on the proliferative and differentiative ability of human mesenchymal stromal cells

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are an attractive candidate for autologous cell therapy, but regenerative potential can be compromised with extensive in vitro cell passaging. Development of viable cell therapies must address the effect of in vitro passaging to maintain overall functionality of expanded MSCs.

METHODS

We examined the effect of repeated mild heat shock on the proliferation and differentiation capability of human adipose-derived MSCs. Adipose tissue MSCs were characterized by means of fluorescence activated cell sorting analysis for expression of CD3, CD14, CD19, CD34, CD44, CD45, CD73, CD90 and CD105. Similarly, the expression of SIRT-1, p16(INK4a) and p21 was determined by means of polymerase chain reaction. Measurements of population doubling, doubling time and superoxide dismutase activity were also determined. Differentiation of expanded MSCs into bone and adipose were analyzed qualitatively and quantitatively.

RESULTS

The strategy led to an increase in expression of SIRT-1 concomitant with enhanced viability, proliferation and delayed senescence. The stressed MSCs showed better differentiation into osteoblasts and adipocytes.

CONCLUSIONS

The results indicate that mild heat shock could be used to maintain MSC proliferative and differentiation potential.

Understanding the role of heat shock protein isoforms in male fertility, aging and apoptosis

Heat shock proteins (HSPs) play a role in the homeostasis, apoptosis regulation and the maintenance of the various other physiological processes. Aging is accompanied by a decrease in the resistance to environmental stress, while mitochondria are primary targets in the process of aging, their expression decreasing with age. Mitochondrion also plays a significant role in the process of spermatogenesis. HSPs have been shown to be involved in apoptosis with some of acting as apoptotic inhibitors and are involved in cytoprotection. In this review we discuss the roles of Hsp 27, 60, 70, and 90 in aging and male infertility and have concluded that these particular HSPs can be used as a molecular markers for mitochondrially- mediated apoptosis, aging and male infertility.

Mesenchymal stromal cell injection protects against oxidative stress in Escherichia coli-induced acute lung injury in mice

BACKGROUND AIMS

Stem cells may be a promising therapy for acute respiratory distress syndrome. Recent in vivo and in vitro studies suggested that the mesenchymal stromal cells (MSCs) have anti-oxidative stress properties. We hypothesized that intravenous injection of bone marrow-derived mesenchymal stem cells (MSCs) could attenuate Escherichia coli-induced acute lung injury (ALI) in mice by controlling the oxidative stress status.

METHODS

Eighty mice were randomly divided into four groups: group 1 (control group) received 25 μL of saline as a vehicle; group 2 contained E coli-induced ALI mice; group 3 included mice that received MSCs before induction of ALI; group 4 included mice that received MSCs after induction of ALI. Lung samples were isolated and assayed for oxidative stress variables and histopathologic analysis. Total anti-oxidant capacity was measured in broncho-alveolar lavage.

RESULTS

Pre- and post-injury MSC injection increased survival, reduced pulmonary edema and attenuated lung injuries in ALI mice. Histologically, MSCs exhibited a considerable degree of preservation of the pulmonary alveolar architecture. An increase of anti-oxidant enzyme activities and a decrease of myeloperoxidase activity and malondialdehyde levels in the MSC recipient groups versus the ALI group were found. Furthermore, the total anti-oxidant capacity and reduced glutathione levels were significantly increased in MSCs recipient groups versus the ALI group. Weak +ve inducible nitric oxide synthase immuno-expression in groups that received MSCs was detected. Pre-injury MSC injection showed better effects than did post-injury MSC injection.

CONCLUSIONS

Systemic bone marrow-derived MSC injection was effective in modulating the oxidative stress status in E coli-induced acute lung injury in mice.

In serum veritas-in serum sanitas? Cell non-autonomous aging compromises differentiation and survival of mesenchymal stromal cells via the oxidative stress pathway

Even tissues capable of complete regeneration, such as bone, show an age-related reduction in their healing capacity. Here, we hypothesized that this decline is primarily due to cell non-autonomous (extrinsic) aging mediated by the systemic environment. We demonstrate that culture of mesenchymal stromal cells (MSCs) in serum from aged Sprague-Dawley rats negatively affects their survival and differentiation ability. Proteome analysis and further cellular investigations strongly suggest that serum from aged animals not only changes expression of proteins related to mitochondria, unfolded protein binding or involved in stress responses, it also significantly enhances intracellular reactive oxygen species production and leads to the accumulation of oxidatively damaged proteins. Conversely, reduction of oxidative stress levels in vitro markedly improved MSC function. These results were validated in an in vivo model of compromised bone healing, which demonstrated significant increase regeneration in aged animals following oral antioxidant administration. These observations indicate the high impact of extrinsic aging on cellular functions and the process of endogenous (bone) regeneration. Thus, addressing the cell environment by, for example, systemic antioxidant treatment is a promising approach to enhance tissue regeneration and to regain cellular function especially in elderly patients.

Autofluorescence properties of murine embryonic stem cells during spontaneous differentiation phases

BACKGROUND AND OBJECTIVE

The autofluorescence (AF) analysis allows in vivo, real-time assessment of cell functional activities, depending on the presence of biomolecules strictly involved in metabolic reactions and acting as endogenous fluorophores. Pluripotent stem cells during differentiation are known to undergo changes in their morphofunctional properties, with particular reference to bioenergetic metabolic signatures involving endogenous fluorophores such as NAD(P)H, flavins, lipofuscin-like lipopigments. Since the development of regenerative therapies based on pluripotent cells requires a careful monitoring of the successful maturation into the desired phenotype, aim of our work is to evaluate the AF potential to assess the differentiation phases in a murine stem cell model.

STUDY DESIGN/MATERIALS AND METHODS

Mouse embryonic stem cells (ESCs) maintained with and without leukemia inhibitory factor (LIF), embryoid bodies (EBs), and EB-derived cells undergoing spontaneous differentiation toward the hematopoietic lineage have been used as a sample models. Cell AF properties have been characterized upon 366-nm excitation, under living conditions and in the absence of exogenous markers. Imaging, microspectrofluorometric techniques, and spectral fitting analysis based on the spectral parameters of each endogenous fluorophore have been applied to estimate their contribution to the whole cell AF emission spectra. Specific cytochemical labeling has been performed to validate AF data.

RESULTS

Depending on the differentiation phases, cells undergo changes in morphology, AF distribution patterns, and AF emission spectral profiles. These latter reflect variations in the single endogenous fluorophore contribution to the overall emission. The coenzyme NAD(P)H accounts for up to 80% of the whole spectral area. The free form prevails on the bound one, and their changes have been investigated in terms of NAD(P)Hbound/free and redox ratios. These values vary in agreement with a slow metabolic activity and prevailing glycolytic metabolism in the undifferentiated HM1 cells, an increased metabolic activity still relying on glycolysis during the early differentiation phases, and an increased oxidative phosphorylation in EB and hematopoietic precursor cells. Lipofuscin-like lipopigments decrease following differentiation, and porphyrins contributing for less than 5%, prevail in the more actively differentiating cells. These results reflect the shift between anaerobic and aerobic respiration following differentiation, consistently with a decreased autophagy of cell organelles (i.e., mitochondria, as a strategy reported in the literature to keep the undifferentiated homeostasis state), higher mitochondrial activity with more numerous NADH binding sites and synthesis of heme as prosthetic group of proteins, that is, cytochromes.

CONCLUSIONS

These data open promising perspectives for the monitoring of stem cells differentiation under living conditions without labeling with exogenous agents (inducing perturbations when used in vivo), or immunomarkers not always available for veterinary and zootechnics, by exploiting endogenous fluorophores as intrinsic biomarkers of cell morphofunctional changes.

Establishment and in vitro culture of porcine spermatogonial germ cells in low temperature culture conditions

The objective of this study was to establish a porcine spermatogonial germ cell (pSGC) line and develop an in vitro culture system. Isolated total testicular cells (TTCs) from 5-day-old porcine testes were primary cultured at 31, 34, and 37°C. Although the time of colony appearance was delayed at 31°C, strong alkaline phosphatase staining, expressions of pluripotency marker genes such as OCT4, NANOG, and THY1, and the gene expressions of the undifferentiated germ cell markers PLZF and protein gene product 9.5 (PGP9.5) were identified compared to 34 and 37°C. Cell cycle analysis for both pSGC and feeder cells at the three temperatures revealed that more pSGCs were in the G2/M phase at 31°C than 37°C at the subculture stage. In vitro, pSGCs could stably maintain undifferentiated germ cell and stem cell characteristics for over 60days during culture at 31°C. Xenotransplantation of pSGCs to immune deficient mice demonstrated a successful colonization and localization on the seminiferous tubule basement membrane in the recipient testes. In conclusion, pSGCs from neonatal porcine were successfully established and cultured for long periods under a low temperature culture environment in vitro.

Mesenchymal stem cells conditioned with glucose depletion augments their ability to repair-infarcted myocardium

Mesenchymal stem cells (MSCs) are an attractive candidate for autologous cell therapy, but their ability to repair damaged myocardium is severely compromised with advanced age. Development of viable autologous cell therapy for treatment of heart failure in the elderly requires the need to address MSC ageing. In this study, MSCs from young (2 months) and aged (24 months) C57BL/6 mice were characterized for gene expression of IGF-1, FGF-2, VEGF, SIRT-1, AKT, p16(INK4a) , p21 and p53 along with measurements of population doubling (PD), superoxide dismutase (SOD) activity and apoptosis. Aged MSCs displayed senescent features compared with cells isolated from young animals and therefore were pre-conditioned with glucose depletion to enhance age affected function. Pre-conditioning of aged MSCs led to an increase in expression of IGF-1, AKT and SIRT-1 concomitant with enhanced viability, proliferation and delayed senescence. To determine the myocardial repair capability of pre-conditioned aged MSCs, myocardial infarction (MI) was induced in 24 months old C57BL/6 wild type mice and GFP expressing untreated and pre-conditioned aged MSCs were transplanted. Hearts transplanted with pre-conditioned aged MSCs showed increased expression of paracrine factors, such as IGF-1, FGF-2, VEGF and SDF-1α. This was associated with significantly improved cardiac performance as measured by dp/dt(max), dp/dt(min), LVEDP and LVDP, declined left ventricle (LV) fibrosis and apoptosis as measured by Masson's Trichrome and TUNEL assays, respectively, after 30 days of transplantation. In conclusion, pre-conditioning of aged MSCs with glucose depletion can enhance proliferation, delay senescence and restore the ability of aged cells to repair senescent infarcted myocardium.

Insects, insecticides and hormesis: evidence and considerations for study

Insects are ubiquitous, crucial components of almost all terrestrial and fresh water ecosystems. In agricultural settings they are subjected to, intentionally or unintentionally, an array of synthetic pesticides and other chemical stressors. These ecological underpinnings, the amenability of insects to laboratory and field experiments, and our strong knowledgebase in insecticide toxicology, make the insect-insecticide model an excellent one to study many questions surrounding hormesis. Moreover, there is practical importance for agriculture with evidence of pest population growth being accelerated by insecticide hormesis. Nevertheless, insects have been underutilized in studies of hormesis. Where hormesis hypotheses have been tested, results clearly demonstrate stimulatory effects on multiple taxa as measured through several biological endpoints, both at individual and population levels. However, many basic questions are outstanding given the myriad of chemicals, responses, and ecological interactions that are likely to occur.

Role of heat shock proteins in stem cell behavior

Stress response is well appreciated to induce the expression of heat shock proteins (Hsps) in the cell. Numerous studies have demonstrated that Hsps function as molecular chaperones in the stabilization of intracellular proteins, repairing damaged proteins, and assisting in protein translocation. Various kinds of stem cells (embryonic stem cells, adult stem cells, or induced pluripotent stem cells) have to maintain their stemness and, under certain circumstances, undergo stress. Therefore, Hsps should have an important influence on stem cells. Actually, numerous studies have indicated that some Hsps physically interact with a number of transcription factors as well as intrinsic and extrinsic signaling pathways. Importantly, alterations in Hsp expression have been demonstrated to affect stem cell behavior including self-renewal, differentiation, sensitivity to environmental stress, and aging. This chapter summarizes recent findings related to (1) the roles of Hsps in maintenance of stem cell dormancy, proliferation, and differentiation; (2) the expression signature of Hsps in embryonic/adult stem cells and differentiated stem cells; (3) the protective roles of Hsps in transplanted stem cells; and (4) the possible roles of Hsps in stem cell aging.

Effect of age and diabetes on the response of mesenchymal progenitor cells to fibrin matrices

Mesenchymal stem cells are showing increasing promise in applications such as tissue engineering and cell therapy. MSC are low in number in bone marrow, and therefore in vitro expansion is often necessary. In vivo, stem cells often reside within a niche acting to protect the cells. These niches are composed of niche cells, stem cells, and extracellular matrix. When blood vessels are damaged, a fibrin clot forms as part of the wound healing response. The clot constitutes a form of stem cell niche as it appears to maintain the stem cell phenotype while supporting MSC proliferation and differentiation during healing. This is particularly appropriate as fibrin is increasingly being suggested as a scaffold meaning that fibrin-based tissue engineering may to some extent recapitulate wound healing. Here, we describe how fibrin modulates the clonogenic capacity of MSC derived from young/old human donors and normal/diabetic rats. Fibrin was prepared using different concentrations to modulate the stiffness of the substrate. MSC were expanded on these scaffolds and analysed. MSC showed an increased self-renewal on soft surfaces. Old and diabetic cells lost the ability to react to these signals and can no longer adapt to the changed environment.

Age-related changes in mesenchymal stem cells derived from rhesus macaque bone marrow

The regeneration potential of mesenchymal stem cells (MSCs) diminishes with advanced age and this diminished potential is associated with changes in cellular functions. This study compared MSCs isolated from the bone marrow of rhesus monkeys (rBMSCs) in three age groups: young (< 5 years), middle (8-10 years), and old (> 12 years). The effects of aging on stem cell properties and indicators of stem cell fitness such as proliferation, differentiation, circadian rhythms, stress response proteins, miRNA expression, and global histone modifications in rBMSCs were analyzed. rBMSCs demonstrated decreased capacities for proliferation and differentiation as a function of age. The production of heat shock protein 70 (HSP70) and heat shock factor 1 (HSF1) were also reduced with increasing age. The level of a core circadian protein, Rev-erb α, was significantly increased in rBMSCs from old animals. Furthermore, analysis of miRNA expression profiles revealed an up-regulation of mir-766 and mir-558 and a down-regulation of mir-let-7f, mir-125b, mir-222, mir-199-3p, mir-23a, and mir-221 in old rBMSCs compare to young rBMSCs. However, there were no significant age-related changes in the global histone modification profiles of the four histone core proteins: H2A, H2B, H3, and H4 on rBMSCs. These changes represent novel insights into the aging process and could have implications regarding the potential for autologous stem cells therapy in older patients.

Angiogenic properties of aged adipose derived mesenchymal stem cells after hypoxic conditioning

Background

Mesenchymal stem cells derived from adipose tissue (ADSC) are multipotent stem cells, originated from the vascular-stromal compartment of fat tissue. ADSC are used as an alternative cell source for many different cell therapies, however in ischemic cardiovascular diseases the therapeutic benefit was modest. One of the reasons could be the use of autologous aged ADSC, which recently were found to have impaired functions. We therefore analysed the effects of age on age markers and angiogenic properties of ADSC. Hypoxic conditioning was investigated as a form of angiogenic stimulation.

Methods

ADSC were harvested from young (1-3 month), adult (12 month) and aged (18-24 month) mice and cultured under normoxic (20%) and hypoxic (1%) conditions for 48 h. Differences in proliferation, apoptosis and telomere length were assessed in addition to angiogenic properties of ADSC.

Results

Proliferation potential and telomere length were decreased in aged ADSC compared to young ADSC. Frequency of apoptotic cells was higher in aged ADSC. Gene expression of pro-angiogenic factors including vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and hepatic growth factor (HGF) were down-regulated with age, which could be restored by hypoxia. Transforming growth factor (TGF-β) increased in the old ADSC but was reduced by hypoxia.

Expression of anti-angiogenic factors including thrombospondin-1 (TBS1) and plasminogen activator inhibitor-1 (PAI-1) did increase in old ADSC, but could be reduced by hypoxic stimulation. Endostatin (ENDS) was the highest in aged ADSC and was also down-regulated by hypoxia. We noted higher gene expression of proteases system factors like urokinase-type plasminogen activator receptor (uPAR), matrix metalloproteinases (MMP2 and MMP9) and PAI-1 in aged ADSC compared to young ADSC, but they decreased in old ADSC. Tube formation on matrigel was higher in the presence of conditioned medium from young ADSC in comparison to aged ADSC.

Conclusions

ADSC isolated from older animals show changes, including impaired proliferation and angiogenic stimulation. Angiogenic gene expression can be partially be improved by hypoxic preconditioning, however the effect is age-dependent. This supports the hypothesis that autologous ADSC from aged subjects might have an impaired therapeutic potential.

Heat shock protein 90 protects rat mesenchymal stem cells against hypoxia and serum deprivation-induced apoptosis via the PI3K/Akt and ERK1/2 pathways

Mesenchymal stem cell (MSC) transplantation has shown a therapeutic potential to repair the ischemic and infracted myocardium, but the effects are limited by the apoptosis and loss of donor cells in host cardiac microenvironment. The aim of this study is to explore the cytoprotection of heat shock protein 90 (Hsp90) against hypoxia and serum deprivation-induced apoptosis and the possible mechanisms in rat MSCs. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was assessed by Hoechst 33258 nuclear staining and flow cytometric analysis with annexin V/PI staining. The gene expression of Toll-like receptor-4 (TLR-4) and V-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ErbB2) was detected by real-time polymerase chain reaction (PCR). The protein levels of cleaved caspase-3, Bcl-2, Bcl-xL, Bax, total-ERK, phospho-ERK, total-Akt, phospho-Akt, and Hsp90 were detected by Western blot. The production of nitric oxide was measured by spectrophotometric assay. Hsp90 improves MSC viability and protects MSCs against apoptosis induced by serum deprivation and hypoxia. The protective role of Hsp90 not only elevates Bcl-2/Bax and Bcl-xL/Bax expression and attenuates cleaved caspase-3 expression via down-regulating membrane TLR-4 and ErbB2 receptors and then activating their downstream PI3K/Akt and ERK1/2 pathways, but also enhances the paracrine effect of MSCs. These findings demonstrated a novel and effective treatment strategy against MSC apoptosis in cell transplantation.

Inhibition of phosphatidylcholine-specific phospholipase C prevents bone marrow stromal cell senescence in vitro

Bone marrow stromal cells (BMSCs) can proliferate in vitro and can be transplanted for treating many kinds of diseases. However, BMSCs become senescent with long-term culture, which inhibits their application. To understand the mechanism underlying the senescence, we investigated the activity of phosphatidylcholine-specific phospholipase C (PC-PLC) and levels of integrin beta4, caveolin-1 and ROS with BMSC senescence. The activity of PC-PLC and levels of integrin beta4, caveolin-1 and ROS increased greatly during cell senescence. Selective inhibition of increased PC-PLC activity with D609 significantly decreased the number of senescence-associated beta galactosidase positive cells in BMSCs. Furthermore, D609 restored proliferation of BMSCs and their differentiation into adipocytes. Moreover, D609 suppressed the elevated levels of integrin beta4, caveolin-1 and ROS. The data suggest that PC-PLC is involved in senescence of BMSCs, and its function is associated with integrin beta4, caveolin-1 and ROS.

Mesenchymal stem cell: present challenges and prospective cellular cardiomyoplasty approaches for myocardial regeneration

Myocardial ischemia and cardiac dysfunction have been known to follow ischemic heart diseases (IHDs). Despite a plethora of conventional treatment options, their efficacies are associated with skepticism. Cell therapies harbor a promising potential for vascular and cardiac repair, which is corroborated by adequate preclinical evidence. The underlying objectives behind cardiac regenerative therapies subsume enhancing angiomyogenesis in the ischemic myocardium, ameliorating cellular apoptosis, regenerating the damaged myocardium, repopulating the lost resident myocardial cells (smooth muscle, cardiomyocyte, and endothelial cells), and finally, decreasing fibrosis with a consequent reduction in ventricular remodeling. Although-cell based cardiomyoplasty approaches have an immense potential, their clinical utilization is limited owing to the increased need for better candidates for cellular cardiomyoplasty, better routes of delivery, appropriate dose for efficient engraftment, and better preconditioning or genetic-modification strategies for the progenitor and stem cells. Mesenchymal stem cells (MSCs) have emerged as powerful candidates in mediating myocardial repair owing to their unique properties of multipotency, transdifferentiation, intercellular connection with the resident cardiomyocytes via connexin 43 (Cx43)-positive gap junctions in the myocardium, and most important, immunomodulation. In this review, we present an in-depth discussion on the complexities associated with stem and progenitor cell therapies, the potential of preclinical approaches involving MSCs for myocardial repair, and an account of the past milestones and ongoing MSC-based trials in humans.

Autologous and allogeneic marrow stromal cells are safe and effective for the treatment of acute kidney injury

Acute kidney injury (AKI) is a major clinical problem associated with high morbidity and mortality. Likely due to its complex pathophysiology, therapies with a single pharmacological agent have generally failed to improve outcomes. In contrast, stem cell-based interventions utilize these cells' ability to simultaneously target multiple pathophysiological components of AKI and thus represent a promising new tool for the treatment of AKI. The aims of the this study were to investigate the long-term outcome and safety of treatment with autologous and allogeneic mesenchymal stem cells (MSCs) after AKI and the role of vascular endothelial growth factor (VEGF) as one of the principal paracrine mediators of renoprotection of MSCs. MSC administration after AKI was not associated with adverse events and proved to be renoprotective in animals with severe renal failure. Identical doses of autologous MSC were more effective than allogeneic. At 3 months, MSCs were not engrafted in any tissues except in the bone marrow in 50% of animals given the highest allogeneic cell dose. There was no long-term fibrotic response in the kidneys attributable to MSC therapy, and animals with severe AKI were protected from development of fibrotic lesions after AKI. Furthermore, this study establishes VEGF as a critical factor mediating renal recovery. VEGF knockdown by small-interfering RNA reduced effectiveness of MSCs significantly and decreased survival. In summary, our results show that both autologous and allogeneic MSC are safe and effective in AKI, and importantly, reduce late renal fibrosis and loss of renal function in surviving animals and that VEGF is a critical factor in renoprotection by MSCs. Together, we posit that these data provide further justification for the conduct of clinical trails in which AKI is treated with MSC.

Contributions of DNA interstrand cross-links to aging of cells and organisms

Impaired DNA damage repair, especially deficient transcription-coupled nucleotide excision repair, leads to segmental progeroid syndromes in human patients as well as in rodent models. Furthermore, DNA double-strand break signalling has been pinpointed as a key inducer of cellular senescence. Several recent findings suggest that another DNA repair pathway, interstrand cross-link (ICL) repair, might also contribute to cell and organism aging. Therefore, we summarize and discuss here that (i) systemic administration of anti-cancer chemotherapeutics, in many cases DNA cross-linking drugs, induces premature progeroid frailty in long-term survivors; (ii) that ICL-inducing 8-methoxy-psoralen/UVA phototherapy leads to signs of premature skin aging as prominent long-term side effect and (iii) that mutated factors involved in ICL repair like ERCC1/XPF, the Fanconi anaemia proteins, WRN and SNEV lead to reduced replicative life span in vitro and segmental progeroid syndromes in vivo. However, since ICL-inducing drugs cause damage different from ICL and since all currently known ICL repair factors work in more than one pathway, further work will be needed to dissect the actual contribution of ICL damage to aging.

Transcriptional profiling of young and old mesenchymal stem cells in response to oxygen deprivation and reparability of the infarcted myocardium

Most clinical studies have used autologous bone marrow (BM) stem cells for myocardial regeneration in elderly patients. We hypothesize that aging impairs the survival and differentiation potential of BM stem cells thus limiting their therapeutic efficacy. BM-derived MSCs from young ((Yng)MSCs; 8-12 weeks) and old ((Old)MSCs; 24-26 months) rats were purified and assessed for their responsiveness to anoxia and reparability of infarcted heart. Higher expression of angiogenic growth factors was observed by (Yng)MSCs under anoxia as compared to (Old)MSCs, cultured either alone or in co-culture ((Co-old)MSCs) with (Yng)MSCs. Likewise, (Yng)MSCs were more tolerant to apoptotic stimuli and showed higher ability to form tubular structures during in vitro Matrigel assay as compared to (Old)MSCs and (Co-old)MSCs with a possible role of p21 and p27 as contributory survival factors. For in vivo studies, acute myocardial infarction model was developed in Fischer-344 rats (n=38). The animals were grouped to receive 70 microl basal DMEM without cells (group 1) or containing 2 x 10(6)(Yng)MSCs (PKH67 labeled; group 2) or (Old)MSCs (PKH26 labeled; group 3) and mixture of (Yng)MSCs + (Old)MSCs (1 x 10(6) cells each; group 4). Histological studies revealed that by day 7, (Yng)MSCs showed elongated morphology with orientation similar to the host muscle architecture. Electron microscopy and confocal imaging after fluorescent immunostaining showed superior angiomyogenic potential of (Yng)MSCs. Echocardiography showed significantly preserved heart function indices in the animals transplanted with (Yng)MSCs. Aging impairs the responsiveness of (Old)MSCs to anoxia and their differentiation potential. (Yng)MSCs fail to alter the survival of (Old)MSCs under in vitro as well as in vivo conditions. It is therefore concluded that transplantation of stem cells from young donors would be a better option for heart cell therapy in future clinical studies.

Hsp90 mediates insulin-like growth factor 1 and interleukin-1beta signaling in an age-dependent manner in equine articular chondrocytes

OBJECTIVE

Many metabolic processes in chondrocytes thought to contribute to age-related changes in the extracellular matrix are influenced by known roles of Hsp90. Age-related decreases in the level of Hsp90 have been documented in numerous cell types and could contribute to cartilage degeneration. The aim of this study was to investigate the roles of age and Hsp90 in insulin-like growth factor 1 (IGF-1) and interleukin-1beta (IL-1beta) signaling in chondrocytes.

METHODS

Levels of Hsp90 messenger RNA (mRNA) and protein, with respect to age, were determined by quantitative real-time polymerase chain reaction (PCR) and Western blot analysis, respectively. The Hsp90 inhibitor geldanamycin (50 nM, 100 nM, or 500 nM) was used to assess age-related responses to Hsp90 with concurrent IGF-1 or IL-1beta stimulation of chondrocytes. Quantitative real-time PCR was used to measure COL2A1 and matrix metalloproteinase 13 (MMP13) gene expression; Western blot analysis was performed to determine the phosphorylation status of p42/44 and Akt/protein kinase B.

RESULTS

The effects of Hsp90 inhibition with geldanamycin were concentration dependent. Inhibition of Hsp90 with 100 nM or 500 nM geldanamycin blocked IGF-1-induced cell proliferation, Akt and p42/44 activation, and COL2A1 expression. Basal and IL-1beta-induced up-regulation of MMP13 mRNA was blocked by all concentrations of geldanamycin tested. Gain-of-function assays with Hsp90 resulted in increased expression of MMP13 mRNA.

CONCLUSION

These results suggest that Hsp90 is involved in opposing signaling pathways of cartilage homeostasis, and that catabolic responses are more sensitive to Hsp90 inhibition than are anabolic responses. Further studies are needed to determine the role of Hsp90 inhibition in osteoarthritis in order to assess its potential as a therapeutic target.

Hormetic prevention of molecular damage during cellular aging of human skin fibroblasts and keratinocytes

Progressive accumulation of molecular damage is a hallmark of cellular aging, which is amenable to intervention and prevention by hormesis through mild stress. Our studies have shown that repeated mild heat stress (RMHS) has antiaging effects on growth and various other cellular and biochemical characteristics of normal human skin fibroblasts undergoing aging in vitro. RMHS at 41 degrees C, for 1 h twice a week, increased the basal levels of various chaperones, reduced the accumulation of oxidatively and glycoxidatively damaged proteins, stimulated proteasomal activities for the degradation of abnormal proteins, improved cellular resistance to ethanol, hydrogen peroxide, and UV-B rays, enhanced the levels of various antioxidant enzymes, and increased the phosphorylation-mediated activities of various stress kinases. RMHS-exposed human fibroblasts are also better protected against glucose- and glyoxal-induced growth inhibition and apoptosis. We have also observed various hormetic effects of RMHS on normal human epidermal keratinocytes, which include increased replicative life span, increased proteasomal activity, and enhanced levels of Na/K-ATPase pump. We are also testing the above effects of RMHS in combination with potential hormetic molecules, such as curcumin, on aging, longevity, and differentiation of human cells in culture.