Hypoxia precondition promotes adipose-derived mesenchymal stem cells based repair of diabetic erectile dysfunction via augmenting angiogenesis and neuroprotection

Hypoxic preconditioning promotes survival of human adipose derived mesenchymal stem cell via expression of prosurvival and proangiogenic biomarkers

Background: Contributing factors for improved survival of human adipose derived mesenchymal stem cells (h-AMSCs) cultured through hypoxia preconditioning, in example apoptosis inhibition involving BCL2 and HSP27 expression, trigger signal expression (VEGF), SCF expression, OCT-4 expression, and CD44+ expression. The objective if this study was to explain the mechanism and role of hypoxic preconditioning and the optimal duration of hypoxic preconditioning exposure to improve survival of h-AMSCs. Methods: An experimental laboratory explorative study (in vitro) with hypoxic preconditioning in h-AMSCs cultures. This research was conducted through four stages. First, isolation of h-AMSCs culture from adipose tissue of patients. Second, the characterization of h-AMSCs from adipose tissue by phenotype (flowcytometry) through CD44+, CD90+ and CD45-expression before being pre-conditioned for hypoxic treatment. Third, the hypoxic preconditioning in h-AMSCs culture (in vitro) was performed with an oxygen concentration of 1% for 24, 48 and 72 hours. Fourth, observation of survival from h-AMSCs culture was tested on the role of CD44+, VEGF, SCF, OCT-4, BCL2, HSP27 with Flowcytometry and apoptotic inhibition by Tunnel Assay method. Results: The result of regression test showed that time difference had an effect on VEGF expression (p<0.001;β=-0.482) and hypoxia condition also influenced VEGF expression (p<0.001;β=0.774). The result of path analysis showed that SCF had effect on OCT-4 expression (p<0.001; β=0.985). The regression test results showed that time effects on HSP27 expression (p<0.001; β=0.398) and hypoxia precondition also affects HSP27 expression (p<0.001; β=0.847). Pathway analysis showed that BCL2 expression inhibited apoptosis (p=0.030; β=-0.442) and HSP27 expression also inhibited apoptosis (p<0,001;β=-0.487). Conclusion: Hypoxic preconditioning of h-AMSC culture has proven to increase the expression of VEGF, SCF, OCT-4, and BCL2 and HSP27. This study demonstrated and explained the existence of a new mechanism of increased h-AMSC survival in cultures with hypoxic preconditioning (O2 1%) via VEGF, SCF, OCT-4, BCL2, and HSP 27.

3-Hydroxy-3-methylglutaryl-CoA synthase 2 facilitates erectile dysfunction via inhibiting autophagy by enhancing the mammalian target of rapamycin pathway in type 1 diabetic mellitus rats

BACKGROUND

The relationship between erectile dysfunction (ED) and type 1 diabetes mellitus (T1DM) is currently a hot topic of medical research. It has been reported that autophagy plays a crucial role in causing erectile dysfunction in T1DM. Recent research has shown that mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) is strongly linked to the development of T1DM. However, the specific mechanism by which it regulates the erectile function is not yet fully understood.

OBJECTIVES

To investigate whether HMGCS2 affects erectile function in type 1 diabetic rats by regulating autophagy in corpus cavernosum endothelial cells (CCECs).

MATERIALS AND METHODS

First, the rat model of T1DM was established. Then, the ratio of maximum penile intracavernous pressure (ICPmax) and mean arterial pressure (MAP) was detected to assess the erectile function in various groups, and the protein expression of HMGCS2, mTOR and p-mTOR was evaluated by western blot (WB) and immunohistochemistry (IHC). To explore the relationship between HMGCS2 and the mTOR signaling pathway in T1DM ED rats, we silenced the expression of HMGCS2 and activated the mTOR signaling pathway with MHY1485 in CCECs and then assessed the expression of beclin1, P62, LC3, autophagosome, endothelial nitric oxide synthase (eNOS), phosphorylation of eNOS (p-eNOS), and nitric oxide (NO) to evaluate autophagy and the erectile function by reverse transcription quantitative polymerase chain reaction and western blot.

RESULTS

The study conducted on T1DM ED rats showed that the expression of HMGCS2 was significantly increased, while the autophagy was suppressed. Additionally, the mTOR signaling pathway was highly activated. In contrast, when HMGCS2 was silenced in vitro, p-mTOR/mTOR was reduced, and autophagy was improved. These effects were accompanied by the enhanced activity of eNOS. Furthermore, when HMGCS2 was silenced and the mTOR signaling pathway was simultaneously activated, the results revealed a decrease in autophagy as well as a reduction in activity of eNOS in comparison to just silencing HMGCS2 alone.

DISCUSSION AND CONCLUSION

HMGCS2 upregulation in T1DM rats inhibited autophagy and eNOS activity by activating the mTOR pathway and led to a decrease in the erectile function.

Physiological oxygen conditions enhance the angiogenic properties of extracellular vesicles from human mesenchymal stem cells

BACKGROUND

Following an ischemic injury to the brain, the induction of angiogenesis is critical to neurological recovery. The angiogenic benefits of mesenchymal stem cells (MSCs) have been attributed at least in part to the actions of extracellular vesicles (EVs) that they secrete. EVs are membrane-bound vesicles that contain various angiogenic biomolecules capable of eliciting therapeutic responses and are of relevance in cerebral applications due to their ability to cross the blood-brain barrier (BBB). Though MSCs are commonly cultured under oxygen levels present in injected air, when MSCs are cultured under physiologically relevant oxygen conditions (2-9% O2), they have been found to secrete higher amounts of survival and angiogenic factors. There is a need to determine the effects of MSC-EVs in models of cerebral angiogenesis and whether those from MSCs cultured under physiological oxygen provide greater functional effects.

METHODS

Human adipose-derived MSCs were grown in clinically relevant serum-free medium and exposed to either headspace oxygen concentrations of 18.4% O2 (normoxic) or 3% O2 (physioxic). EVs were isolated from MSC cultures by differential ultracentrifugation and characterized by their size, concentration of EV specific markers, and their angiogenic protein content. Their functional angiogenic effects were evaluated in vitro by their induction of cerebral microvascular endothelial cell (CMEC) proliferation, tube formation, and angiogenic and tight junction gene expressions.

RESULTS

Compared to normoxic conditions, culturing MSCs under physioxic conditions increased their expression of angiogenic genes SDF1 and VEGF, and subsequently elevated VEGF-A content in the EV fraction. MSC-EVs demonstrated an ability to induce CMEC angiogenesis by promoting tube formation, with the EV fraction from physioxic cultures having the greatest effect. The physioxic EV fraction further upregulated the expression of CMEC angiogenic genes FGF2, HIF1, VEGF and TGFB1, as well as genes (OCLN and TJP1) involved in BBB maintenance.

CONCLUSIONS

EVs from physioxic MSC cultures hold promise in the generation of a cell-free therapy to induce angiogenesis. Their positive angiogenic effect on cerebral microvascular endothelial cells demonstrates that they may have utility in treating ischemic cerebral conditions, where the induction of angiogenesis is critical to improving recovery and neurological function.

Adipose-derived Mesenchymal Stem Cells Therapy as a new Treatment Option for Diabetes Mellitus

The worldwide increase in the prevalence of diabetes mellitus has raised the demand for new therapeutic strategies targeting diabetic symptoms and its chronic complications. Among different treatment options for diabetes, adipose-derived mesenchymal stem cells (ADMSCs) therapy attract the most attention. The therapeutic effects of ADMSCs are based primarily on their paracrine release of immunomodulatory, anti-inflammatory, and trophic factors. Animal models of diabetes as well as human clinical trials have shown that ADMSCs can effectively facilitate endogenous β cell regeneration, preserve residual β cell mass, reduce islet graft rejection, regulate the immune system, and ultimately improve insulin sensitivity or ameliorate insulin resistance in peripheral tissues. Nevertheless, transplantation of mesenchymal stem cells is associated with certain risks; therefore recently much attention has been devoted to ADMSCs derivatives, such as exosomes or conditioned media, as therapeutic agents for the treatment of diabetes. Compared to ADMSCs, cell-free therapy has even better therapeutic potential. This narrative review summarizes recent outcomes and molecular mechanisms of ADMSCs action in the treatment for both type 1 DM and type 2 DM, as well as shows their feasibility, benefits, and current limitations.

Secretome of Adipose-Derived Stem Cells Cultured in Platelet Lysate Improves Migration and Viability of Keratinocytes

Chronic wounds depict a silent epidemic challenging medical professionals worldwide. Regenerative medicine uses adipose-derived stem cells (ADSC) in promising new therapies. In this study, platelet lysate (PL) as a xenogen-free substitute for foetal bovine serum (FBS) in ADSC culture was used to create an ADSC secretome containing cytokines for optimal wound healing conditions. The ADSC secretome was tested on keratinocytes for migrational behaviour and viability. Therefore, human ADSC were characterized under FBS (10%) and PL (5% and 10%) substitution, regarding morphology, differentiation, viability, gene and protein expression. ADSC were then cultured in 5% PL and their secretome was used for stimulation of keratinocyte migration and viability. To enhance the effect, ADSC were treated with Epithelial Growth Factor (EGF, 100 ng/mL) and hypoxia (1% O₂). In both PL and FBS groups, ADSC expressed typical stem cell markers. PL induced a significantly higher increase in cell viability compared to FBS substitution. ADSC secretome contained various beneficial proteins which enhance the wound healing capacity of keratinocytes. This could be optimized treating ADSC with hypoxia and EGF. In conclusion, the study shows that ADSC cultivated in 5% PL can effectively support wound healing conditions and can be considered as a promising new therapy for individual treatment of chronic wound disorders.

The Function of BDNF and Its Receptor in the Male Genitourinary System and Its Potential Clinical Application

Background: Brain-derived neurotrophic factor (BDNF), as a member of the nerve growth factor family, has been mentioned more and more frequently in recent literature reports. Among them, content about the male genitourinary system is also increasing. Objective and Rationale: BDNF plays an important role in the male genitourinary system. At the same time, the literature in this field is constantly increasing. Therefore, we systematically summarized the literature in order to more intuitively show the function of BDNF and its receptor in the male genitourinary system and its potential clinical application. Search Methods: An electronic search of, e.g., PubMed, scholar.google and Scopus, for articles relating to BDNF and its receptor in the male genitourinary system. Outcomes: In the male genitourinary system, BDNF and its receptors TrkB and p75 participate in a series of normal physiological activities, such as the maturation and morphogenesis of testes and epididymis and maintenance of isolated sperm motility. Similarly, an imbalance of the circulating concentration of BDNF also mediates the pathophysiological process of many diseases, such as prostate cancer, benign prostatic hyperplasia, male infertility, diabetes erectile dysfunction, penile sclerosis, and bladder fibrosis. As a consequence, we conclude that BDNF and its receptor are key regulatory proteins in the male genitourinary system, which can be used as potential therapeutic targets and markers for disease diagnosis.

Advances in the research of the role of macrophage/microglia polarization-mediated inflammatory response in spinal cord injury

It is often difficult to regain neurological function following spinal cord injury (SCI). Neuroinflammation is thought to be responsible for this failure. Regulating the inflammatory response post-SCI may contribute to the recovery of neurological function. Over the past few decades, studies have found that macrophages/microglia are one of the primary effector cells in the inflammatory response following SCI. Growing evidence has documented that macrophages/microglia are plastic cells that can polarize in response to microenvironmental signals into M1 and M2 macrophages/microglia. M1 produces pro-inflammatory cytokines to induce inflammation and worsen tissue damage, while M2 has anti-inflammatory activities in wound healing and tissue regeneration. Recent studies have indicated that the transition from the M1 to the M2 phenotype of macrophage/microglia supports the regression of inflammation and tissue repair. Here, we will review the role of the inflammatory response and macrophages/microglia in SCI and repair. In addition, we will discuss potential molecular mechanisms that induce macrophage/microglia polarization, with emphasis on neuroprotective therapies that modulate macrophage/microglia polarization, which will provide new insights into therapeutic strategies for SCI.

State of the field: cellular and exosomal therapeutic approaches in vascular regeneration

Pathologies of the vasculature including the microvasculature are often complex in nature, leading to loss of physiological homeostatic regulation of patency and adequate perfusion to match tissue metabolic demands. Microvascular dysfunction is a key underlying element in the majority of pathologies of failing organs and tissues. Contributing pathological factors to this dysfunction include oxidative stress, mitochondrial dysfunction, endoplasmic reticular (ER) stress, endothelial dysfunction, loss of angiogenic potential and vascular density, and greater senescence and apoptosis. In many clinical settings, current pharmacologic strategies use a single or narrow targeted approach to address symptoms of pathology rather than a comprehensive and multifaceted approach to address their root cause. To address this, efforts have been heavily focused on cellular therapies and cell-free therapies (e.g., exosomes) that can tackle the multifaceted etiology of vascular and microvascular dysfunction. In this review, we discuss 1) the state of the field in terms of common therapeutic cell population isolation techniques, their unique characteristics, and their advantages and disadvantages, 2) common molecular mechanisms of cell therapies to restore vascularization and/or vascular function, 3) arguments for and against allogeneic versus autologous applications of cell therapies, 4) emerging strategies to optimize and enhance cell therapies through priming and preconditioning, and, finally, 5) emerging strategies to bolster therapeutic effect. Relevant and recent clinical and animal studies using cellular therapies to restore vascular function or pathologic tissue health by way of improved vascularization are highlighted throughout these sections.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

Preconditioning of Hypoxic Culture Increases The Therapeutic Potential of Adipose Derived Mesenchymal Stem Cells

Various in vitro preconditioning strategies have been implemented to increase the regenerative capacity of MSCs. Among them are modulation of culture atmosphere (hypoxia or anoxia), three-dimensional culture (3D), addition of trophic factors (in the form of growth factors, cytokines or hormones), lipopolysaccharides, and pharmacological agents. Preconditioning mesenchymal stem cells by culturing them in a hypoxic environment, which resembles the natural oxygen environment of the tissues (1% –7%) and not with standard culture conditions (21%), increases the survival of these cells via Hypoxia Inducible Factor-1α (HIF-1a) and via Akt-dependent mechanisms. In addition, the hypoxic precondition stimulates the secretion of pro-angiogenic growth factors, increases the expression of chemokines SDF-1 (stromal cell-derived factor-1) and its receptor CXCR4 (chemokine receptor type 4) - CXCR7 (chemokine receptor type 7) and increases engraftment of stem cell. This review aims to provide an overview of the preconditioned hypoxic treatment to increase the therapeutic potential of adipose-derived mesenchymal stem cells.  

Stem cell therapy and diabetic erectile dysfunction: A critical review

Erectile dysfunction (ED) has been identified as one of the most frequent chronic complications of diabetes mellitus (DM). The prevalence of ED is estimated to be about 67.4% in all DM cases worldwide. The pathophysiological process leading to ED involves endothelial, neurological, hormonal, and psychological factors. In DM, endothelial and neurological factors play a crucial role. Damages in the blood vessels and erectile tissue due to insulin resistance are the hallmark of ED in DM. The current treatments for ED include phosphodiesterase-5 inhibitors and penile prosthesis surgery. However, these treatments are limited in terms of just relieving the symptoms, but not resolving the cause of the problem. The use of stem cells for treating ED is currently being studied mostly in experimental animals. The stem cells used are derived from adipose tissue, bone, or human urine. Most of the studies observed an improvement in erectile quality in the experimental animals as well as an improvement in erectile tissue. However, research on stem cell therapy for ED in humans remains to be limited. Nevertheless, significant findings from studies using animal models indicate a potential use of stem cells in the treatment of ED.

Effects of hypoxia on Achilles tendon repair using adipose tissue-derived mesenchymal stem cells seeded small intestinal submucosa

BACKGROUND

The study was performed to evaluate the feasibility of utilizing small intestinal submucosa (SIS) scaffolds seeded with adipose-derived mesenchymal stem cells (ADMSCs) for engineered tendon repairing rat Achilles tendon defects and to compare the effects of preconditioning treatments (hypoxic vs. normoxic) on the tendon healing.

METHODS

Fifty SD rats were randomized into five groups. Group A received sham operation (blank control). In other groups, the Achilles tendon was resected and filled with the original tendon (Group B, autograft), cell-free SIS (Group C), or SIS seeded with ADMSCs preconditioned under normoxic conditions (Group D) or hypoxic conditions (Group E). Samples were collected 4 weeks after operation and analyzed by histology, immunohistochemistry, and tensile testing.

RESULTS

Histologically, compared with Groups C and D, Group E showed a significant improvement in extracellular matrix production and a higher compactness of collagen fibers. Group E also exhibited a significantly higher peak tensile load than Groups D and C. Additionally, Group D had a significantly higher peak load than Group C. Immunohistochemically, Group E exhibited a significantly higher percentage of MKX + cells than Group D. The proportion of ADMSCs simultaneously positive for both MKX and CM-Dil observed from Group E was also greater than that in Group D.

CONCLUSIONS

In this animal model, the engineered tendon grafts created by seeding ADMSCs on SIS were superior to cell-free SIS. The hypoxic precondition further improved the expression of tendon-related genes in the seeded cells and increased the rupture load after grafting in the Achilles tendon defects.

Adipose-Derived Mesenchymal Stem Cells From a Hypoxic Culture Improve Neuronal Differentiation and Nerve Repair

Hypoxic expansion has been demonstrated to enhance in vitro neuronal differentiation of bone-marrow derived mesenchymal stem cells (BMSCs). Whether adipose-derived mesenchymal stem cells (ADSCs) increase their neuronal differentiation potential following hypoxic expansion has been examined in the study. Real-time quantitative reverse transcription-polymerase chain reaction and immunofluorescence staining were employed to detect the expression of neuronal markers and compare the differentiation efficiency of hypoxic and normoxic ADSCs. A sciatic nerve injury animal model was used to analyze the gastrocnemius muscle weights as the outcomes of hypoxic and normoxic ADSC treatments, and sections of the regenerated nerve fibers taken from the conduits were analyzed by histological staining and immunohistochemical staining. Comparisons of the treatment effects of ADSCs and BMSCs following hypoxic expansion were also conducted in vitro and in vivo. Hypoxic expansion prior to the differentiation procedure promoted the expression of the neuronal markers in ADSC differentiated neuron-like cells. Moreover, the conduit connecting the sciatic nerve gap injected with hypoxic ADSCs showed the highest recovery rate of the gastrocnemius muscle weights in the animal model, suggesting a conceivable treatment for hypoxic ADSCs. The percentages of the regenerated myelinated fibers from the hypoxic ADSCs detected by toluidine blue staining and myelin basic protein (MBP) immunostaining were higher than those of the normoxic ones. On the other hand, hypoxic expansion increased the neuronal differentiation potential of ADSCs compared with that of the hypoxic BMSCs in vitro. The outcomes of animals treated with hypoxic ADSCs and hypoxic BMSCs showed similar results, confirming that hypoxic expansion enhances the neuronal differentiation potential of ADSCs in vitro and improves in vivo therapeutic potential.

Hypoxia further exacerbates woody breast myopathy in broilers via alteration of satellite cell fate

Woody breast (WB) condition has created a variety of challenges for the global poultry industry. To date, there are no effective treatments or preventative measures due to its unknown (undefined) etiology. Several potential mechanisms including oxidative stress, fiber-type switching, cellular damage, and altered intracellular calcium levels have been proposed to play a key role in the progression of the WB myopathy. In a previous study, we have shown that WB is associated with hypoxia-like status and dysregulated oxygen homeostasis. As satellite cells (SC) play a pivotal role in muscle fiber repair and remodeling under stress conditions, we undertook the present study to determine satellite cell fate in WB-affected birds when reared in either normoxic or hypoxic conditions. Modern random bred broilers from 2015 (n = 200) were wing banded and reared under standard brooding practices for the first 2 wk post-hatch. At 15 d, chicks were divided in 2 body weight-matched groups and reared to 6 wk in either control local altitude or hypobaric chambers with simulated altitude of 6,000 ft. Birds were provided ad libitum access to water and feed, according to the Cobb recommendations. At 6 wk of age, birds were processed and scored for WB, and breast samples were collected from WB-affected and unaffected birds for molecular analyses (n = 10/group). SCs were isolated from normal breast muscle, cultured in vitro, and exposed to normoxia or hypoxia for 2 h. The expression of target genes was determined by qPCR using 2^−∆∆Ct method. Protein distribution and expression were determined by immunofluorescence staining and immunoblot, respectively. Data were analyzed by the Student's t test with significance set at P < 0.05. Multiple satellite cell markers, myogenic factor (Myf)-5 and paired box (PAX)-7 were significantly decreased at the mRNA and protein levels in the breast muscle from WB-affected birds compared to their unaffected counterparts. Lipogenic-and adipogenic-associated factors (acetyl-CoA carboxylase, ACCα; fatty acid synthase, FASN, malic enzyme, ME; and ATP citrate lyase, ACLY) were activated in WB-affected birds. These data were supported by an in vitro study where hypoxia decreased the expression of Myf5 and Pax7, and increased that of ACCα, FASN, ME, and ACLY. Together, these data indicate that under hypoxic condition, SC change fate by switching from a myogenic to an adipogenic program, which explains at least partly, the etiology of the WB myopathy.

The effect of hypoxia on the proteomic signature of pig adipose-derived stromal/stem cells (pASCs)

Human adipose-derived stem cells (ASCs) have potential to improve wound healing; however, their equivalents from domestic animals have received less attention as an alternative cell-based therapy for animals or even humans. Hypoxia is essential for maintaining stem cell functionality in tissue-specific niches. However, a cellular response to low oxygen levels has not been demonstrated in pig ASCs. Hence, the goal of our study was to characterize ASCs isolated from the subcutaneous fat of domestic pigs (pASCs) and examine the effect of hypoxia on their proteome and functional characteristics that might reproduce pASCs wound healing ability. Analysis of immunophenotypic and functional markers demonstrated that pASCs exhibited characteristics of mesenchymal stem cells. Proteomic analysis revealed 70 differentially abundant proteins between pASCs cultured under hypoxia (1% O₂) or normoxia (21% O₂). Among them, 42 proteins were enriched in the cells exposed to low oxygen, whereas 28 proteins showed decrease expression following hypoxia. Differentially expressed proteins were predominantly involved in cell metabolism, regulation of focal and intracellular communication, and attributed to wound healing. Functional examination of hypoxic pASCs demonstrated acquisition of contractile abilities in vitro. Overall, our results demonstrate that hypoxia pre-conditioning impacts the pASC proteome signature and contractile function in vitro and hence, they might be considered for further cell-based therapy study on wound healing.

Adipose-derived mesenchymal stem cell seeded Atelocollagen scaffolds for cardiac tissue engineering

ADMSCs were isolated from subcutaneous adipose tissue, characterized and cultured in vitro. GFP-labeled ADMSCs can grow and proliferate well on the Atelocollagen scaffolds, and induced by 5-aza the cells can differentiate into cardio-like cells. 3D cultured ADMSCs on Atelocollagen scaffolds were transplanted into mice ischemia myocardium, and have good biocompatibility with host cardio tissue.

Harnessing Stem Cell Potential for the Treatment of Erectile Function in Men with Diabetes Mellitus: From Preclinical/Clinical Perspectives to Penile Tissue Engineering

Background::

According to the World Health Organization, more than 150 million people are diabetic, and this number will increase twofold by the year 2025. Diabetes-related complications affect all body organ systems, including the penis. Diabetes-induced Erectile Dysfunction (ED) is caused by neuropathy of the penile nerves and vasculopathy involving the smooth muscle and endothelium of the corpus cavernosum.

Objective::

This study aims to present an overview of Stem Cell (SC) research in diabetic animal models of ED, focusing on the function, signaling, and niches that have a prominent role in the regeneration of cavernosal cells and penile tissues. We highlight common erectile pathologies caused by diabetes and review relevant preclinical trials. We also discuss paracrine mechanisms of various SC therapies involved in the repair of endothelial cells and cavernous nerves in these diabetic models.

Method::

A PubMed search was performed, with dates ranging from inception until Mar 31, 2019.

Results::

This review provides a comprehensive evaluation of the various strategies that have been investigated for improving SC delivery methods, through preclinical literature and published clinical trials regarding ED in men with diabetes. Various cell-type applications have benefited erectile function in diabetic models of ED.

Conclusion::

This review examines the progress and remaining challenges in diabetes-related SC research regarding ED. Moving forward, it is only with a combined effort of basic biology and translational work that the potential of SC-based therapies in diabetes in ED can be realized.

Engineered Human Adipose-Derived Stem Cells Inducing Endothelial Lineage and Angiogenic Response

IMPACT STATEMENT

With respect to the persistent hunt for a cytocompatible, translational, reproducible, and effective approach in engineering primary human adipose-derived mesenchymal stromal cells (hADMSCs), we demonstrate the application of Neon^® Transfection System in adequate transient delivery of angiogenic factors. The study presents functional assessment of this approach in vitro, with two notable outcomes at translational perspective; (1) Bioengineered hADMSCs secretome does induce endothelial lineage commitment of stem cells at both transcriptional and translational levels and (2) Combinatorial delivery of vascular endothelial growth factor A and hypoxia-inducible factor-1α by bioengineered hADMSCs enhance upregulation of endothelial cell proliferation, migration-associated wound closure, and endothelial tube formation with augmented Flk-1 expression, as compared with their independent actions. The methods described in this study paves way for in vivo evaluation on identification of appropriate chronic wound models and subsequently for clinical translation. The technology developed also has application in vascularization of tissue-engineered constructs.

Hypoxic Preconditioning Enhances Survival and Proangiogenic Capacity of Human First Trimester Chorionic Villus-Derived Mesenchymal Stem Cells for Fetal Tissue Engineering

Prenatal stem cell-based regenerative therapies have progressed substantially and have been demonstrated as effective treatment options for fetal diseases that were previously deemed untreatable. Due to immunoregulatory properties, self-renewal capacity, and multilineage potential, autologous human placental chorionic villus-derived mesenchymal stromal cells (CV-MSCs) are an attractive cell source for fetal regenerative therapies. However, as a general issue for MSC transplantation, the poor survival and engraftment is a major challenge of the application of MSCs. Particularly for the fetal transplantation of CV-MSCs in the naturally hypoxic fetal environment, improving the survival and engraftment of CV-MSCs is critically important. Hypoxic preconditioning (HP) is an effective priming approach to protect stem cells from ischemic damage. In this study, we developed an optimal HP protocol to enhance the survival and proangiogenic capacity of CV-MSCs for improving clinical outcomes in fetal applications. Total cell number, DNA quantification, nuclear area test, and cell viability test showed HP significantly protected CV-MSCs from ischemic damage. Flow cytometry analysis confirmed HP did not alter the immunophenotype of CV-MSCs. Caspase-3, MTS, and Western blot analysis showed HP significantly reduced the apoptosis of CV-MSCs under ischemic stimulus via the activation of the AKT signaling pathway that was related to cell survival. ELISA results showed HP significantly enhanced the secretion of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) by CV-MSCs under an ischemic stimulus. We also found that the environmental nutrition level was critical for the release of brain-derived neurotrophic factor (BDNF). The angiogenesis assay results showed HP-primed CV-MSCs could significantly enhance endothelial cell (EC) proliferation, migration, and tube formation. Consequently, HP is a promising strategy to increase the tolerance of CV-MSCs to ischemia and improve their therapeutic efficacy in fetal clinical applications.

Comparison of the therapeutic effects of adipose‑derived and bone marrow mesenchymal stem cells on erectile dysfunction in diabetic rats

The aim of the present study was to compare the effects of adipose‑derived mesenchymal stem cell (ADSC) and bone marrow mesenchymal stem cell (BMSC) transplantation into the corpora cavernosa of diabetic rats with erectile function. ADSCs and BMSCs were isolated and identified by flow cytometry. Rats with streptozocin‑induced diabetes were screened using apomorphine to obtain a rat model of diabetic erectile dysfunction, followed by transplantation of ADSCs and BMSCs into the corpora cavernosa. Two weeks later, the rats were again injected with apomorphine, the intracavernous pressure (ICP) and mean arterial pressure (MAP) of the penile tissue were measured, and the corpus cavernosum tissues were harvested. Angiogenic endothelial nitric oxide synthase (eNOS) expression was detected by western blotting and immunofluorescence analysis. The blood vessels in the corpus cavernosum were observed following hematoxylin and eosin (H&E) staining, and the expression of collagen was detected by Sirius Red staining. The cellular ultrastructure was examined by transmission electron microscopy. Intracavernous injection of ADSCs significantly increased ICP and ICP/MAP. Western blotting and immunofluorescence results revealed that ADSC treatment improved the expression of eNOS in the penile tissue of diabetic rats. The H&E staining results demonstrated that ADSC treatment promoted revascularization of the corpus cavernosum, and the results of Sirius Red staining revealed that ADSC treatment reduced penile collagen in diabetic rats. Transmission electron microscopy examination revealed that the ultrastructure of the tissues in the ADSC‑treated group was more complete compared with that in the untreated diabetic model group. In conclusion, ADSCs were found to be more effective compared with BMSCs in treating diabetes‑related erectile dysfunction.

Transplantation of adipose-derived stem cells overexpressing inducible nitric oxide synthase ameliorates diabetes mellitus-induced erectile dysfunction in rats

Background

Erectile dysfunction is a major complication of diabetes mellitus. Adipose-derived stem cells (ADSCs) have attracted much attention as a promising tool for the treatment of diabetes mellitus-induced erectile dysfunction (DMED). Inducible nitric oxide synthase (iNOS) plays an important role in protecting penile tissues from fibrosis. The aim of this study was to determine the efficacy of ADSCs overexpressing iNOS on DMED in rats.

Methods

ADSCs were isolated and infected with adenovirus overexpressing iNOS (named as ADSCs-iNOS). The expression of iNOS was detected using western blot analysis and real-time PCR. Rats were randomly assigned into five groups: control group, DMED group, ADSCs group, ADSCs-EGFP group and ADSCs-iNOS group. 5 × 10⁵ cells were given once via the intracorporal route. Two weeks after treatment, erectile function was assessed by electrical stimulation of the cavernous nerve. Penile tissues were obtained and evaluated at histology level.

Results

We found that ADSCs-iNOS had significantly higher expression of iNOS at mRNA and protein levels and generated more nitric oxide (NO). ADSCs-iNOS reduced collagen I and collagen IV expression of corpus cavernosum smooth muscle cells (CCSMCs) in cell co-culture model. Transforming growth factor-β1 expression in CCSMCs reduced following co-culture with ADSCs-iNOS. Injection of ADSCs-iNOS significantly ameliorated DMED in rats and decreased collagen/smooth muscle cell ratio of penile tissues. Moreover, elevated NO and cyclic guanosine monophosphate concentrations were detected in penile tissues of ADSCs-iNOS group.

Conclusion

Taken together, ADSCs-iNOS significantly improved erectile function of DMED rats. The therapeutic effect may be achieved by increased NO generation and the suppression of collagen I and collagen IV expression in the CCSMCs to decrease penile fibrosis.

Metabolism in Human Mesenchymal Stromal Cells: A Missing Link Between hMSC Biomanufacturing and Therapy?

Human mesenchymal stem cells (hMSCs) are the most commonly-tested adult stem cells in cell therapy. While the initial focus for hMSC clinical applications was to exploit their multi-potentiality for cell replacement therapies, it is now apparent that hMSCs empower tissue repair primarily by secretion of immuno-regulatory and pro-regenerative factors. A growing trend in hMSC clinical trials is the use of allogenic and culture-expanded cells because they are well-characterized and can be produced in large scale from specific donors to compensate for the donor pathological condition(s). However, donor morbidity and large-scale expansion are known to alter hMSC secretory profile and reduce therapeutic potency, which are significant barriers in hMSC clinical translation. Therefore, understanding the regulatory mechanisms underpinning hMSC phenotypic and functional property is crucial for developing novel engineering protocols that maximize yield while preserving therapeutic potency. hMSC are heterogenous at the level of primary metabolism and that energy metabolism plays important roles in regulating hMSC functional properties. This review focuses on energy metabolism in regulating hMSC immunomodulatory properties and its implication in hMSC sourcing and biomanufacturing. The specific characteristics of hMSC metabolism will be discussed with a focus on hMSC metabolic plasticity and donor- and culture-induced changes in immunomodulatory properties. Potential strategies of modulating hMSC metabolism to enhance their immunomodulation and therapeutic efficacy in preclinical models will be reviewed.

Inactivation of the Ras/MAPK/PPARγ signaling axis alleviates diabetic mellitus-induced erectile dysfunction through suppression of corpus cavernosal endothelial cell apoptosis by inhibiting HMGCS2 expression

PURPOSE

Diabetic mellitus-induced erectile dysfunction (DMED) represents a significant complication associated with diabetes mellitus (DM) that greatly affects human life quality. Various reports have highlighted the involvement of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) in the regulation of mitochondrial fatty acid oxidation, which has also been linked with DM. Through bioinformatics analysis, HMGCS2 was determined to be a novel target among DM patients suffering from erectile dysfunction (ED), and enriched in the Ras/ERK/PPAR signaling axis. Owing to the fact that the key mechanism HMGCS2 involved in DM remains largely unknown, we set out to investigate the role of the Ras/MAPK/PPARγ signaling axis and HMGCS2 in the corpus cavernosal endothelial cells (CCECs) of rats with DMED.

METHODS

Firstly, bioinformatics analysis was used to screen out differentially expressed genes in DMED. Then, to investigate the influence of the Ras/MAPK/PPARγ signaling axis and HMGCS2 on DMED, a rat model of DMED was established and injected with Simvastatin and si-Hmgcs2. The individual expression patterns of Ras, MAPK, PPARγ and HMGCS2 were determined by RT-qPCR, immunohistochemistry and western blot analysis methods. Afterwards, to investigate the mechanism of Ras/MAPK/PPARγ signaling axis and HMGCS2, CCECs were isolated from DMED rats and transfected with agonists and inhibitors of the Ras/MAPK/PPARγ signaling axis and siRNA of HMGCS2, with their respective functions in apoptosis and impairment of CCECs evaluated using TUNEL staining and flow cytometry.

RESULTS

Microarray analysis and KEGG pathway enrichment analysis revealed that Ras/ERK/PPAR signaling axis mediated HMGCS2 in DMED. Among the DMED rats, the Ras/MAPK/PPAR signaling axis was also activated while the expression of HMGCS2 was upregulated. The activation of Ras was determined to be capable of upregulating ERK expression which resulted in the inhibition of the transcription of PPARγ and subsequent upregulation of HMGCS2 expression. The inhibited activation of the Ras/ERK/PPAR signaling axis and silencing HMGCS2 were observed to provide an alleviatory effect on the injury of DMED while acting to inhibit the apoptosis of CCECs.

CONCLUSION

Collectively, the key findings suggested that suppression of the Ras/MAPK/PPARγ signaling axis could downregulate expression of HMGCS2, so as to alleviate DMED. This study defines the potential treatment for DMED through inhibition of the Ras/MAPK/PPARγ signaling axis and silencing HMGCS2.

Pathological Impacts of Chronic Hypoxia on Alzheimer's Disease

Chronic hypoxia is considered as one of the important environmental factors contributing to the pathogenesis of Alzheimer's disease (AD). Many chronic hypoxia-causing comorbidities, such as obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD), have been reported to be closely associated with AD. Increasing evidence has documented that chronic hypoxia may affect many pathological aspects of AD including amyloid β (Aβ) metabolism, tau phosphorylation, autophagy, neuroinflammation, oxidative stress, endoplasmic reticulum (ER) stress, and mitochondrial and synaptic dysfunction, which may collectively result in neurodegeneration in the brain. In this Review, we briefly summarize the effects of chronic hypoxia on AD pathogenesis and discuss the underlying mechanisms. Since chronic hypoxia is common in the elderly and may contribute to the pathogenesis of AD, prospective prevention and treatment targeting hypoxia may be helpful to delay or alleviate AD.

Engineered Mesenchymal Stem Cells Expressing Stromal Cell-derived Factor-1 Improve Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Effective therapies for erectile dysfunction (ED) associated with diabetes mellitus (DM) are needed. In this study, the effects of stromal cell-derived factor-1 (SDF-1)-expressing engineered mesenchymal stem cells (SDF-1 eMSCs) and the relevant mechanisms in the corpus cavernosum of a streptozotocin (STZ)-induced DM ED rat model were evaluated. In a randomized controlled trial, Sprague–Dawley (SD) rats (n = 48) were divided into four groups (n = 12/group): Normal (control), DM ED (diabetes induced by STZ), DM ED + BM-MSC (treated with bone marrow [BM]-derived MSCs), and DM ED + SDF-1 eMSC (treated with SDF-1-expressing BM-MSCs). After four weeks, intracavernosal pressure (ICP), an indicator of erectile function, was 0.75 ± 0.07 in the normal group, 0.27 ± 0.08 in the DM ED group, 0.42 ± 0.11 in the DM ED + BM-MSC group, and 0.58 ± 0.11 in the DM ED + SDF-1 eMSC group. BM-MSCs, especially SDF-1 eMSCs, improved ED (p < 0.05). SDF-1 eMSC treatment improved the smooth muscle content in the corpus cavernosum (p < 0.05). As SDF-1 expression increased, ED recovery improved. In the SDF-1 eMSC group, levels of neuronal nitric oxide synthase (nNOS) and phosphorylated endothelial NOS (p-eNOS) were higher than those in other groups (p < 0.05). In addition, high stromal cell-derived factor-1 (SDF-1) expression was associated with increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in DM ED rats (p < 0.05). Higher levels of phosphorylated protein kinase B (p-AKT)/protein kinase B (AKT) (p < 0.05) and B-cell lymphoma-2 (Bcl-2) and lower levels of the apoptosis factors Bcl2-associated x (Bax) and caspase-3 were observed in the MSC-treated group than in the DM ED group (p < 0.05). SDF-1 eMSCs showed beneficial effects on recovery from erectile function.

Autologous fat grafting: Latest insights

A recent rise in the use of autologous fat transfer for soft tissue augmentation has paralleled the increasing popularity of liposuction body contouring. This creates a readily available and inexpensive product for lipografting, which is the application of lipoaspirated material. Consistent scientific proof about the long-term viability of the transferred fat is not available. Clinically, there is a reabsorption rate which has been reported to range from 20 to 90%. Results can be unpredictable with overcorrection and regular need for additional interventions. In this review, adipogenesis physiology and the adipogenic cascade from adipose-derived stem cells to adult adipocytes is extensively described to determine various procedures involved in the fat grafting technique. Variables in structure and physiology, adipose tissue harvesting- and processing techniques, and the preservation of fat grafts are taken into account to collect reproducible scientific data to establish standard in vitro and in vivo models for experimental fat grafting. Adequate histological staining for fat tissue, immunohistochemistry and viability assays should be universally used in experiments to be able to produce comparative results. By analysis of the applied methods and comparison to similar experiments, a conclusion concerning the ideal technique to improve clinical outcome is proposed.

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Adipogenic physiology is described to determine various procedures involved in the fat grafting technique.

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Clinical studies on fat grafting have confirmed an unpredictable result.

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After analysis of the literature and despite attempts to eliminate confounding factors, on every step of the fat transfer technique a number of studies with conflicting results exist.

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Adequate histological staining for fat tissue, immunohistochemistry and viability assays should be universally used in experiments to be able to produce comparative results.

Vascularization of PLGA-based bio-artificial beds by hypoxia-preconditioned mesenchymal stem cells for subcutaneous xenogeneic islet transplantation

BACKGROUND

Subcutaneous tissue is an attractive extra-hepatic heterotopic site for islet transplantation; however, poor oxygen tension and blood supply during early engraftment of implanted islets have limited the use of this site in clinical applications.

METHODS

This study investigated the vascularization potential of hypoxia-preconditioned mesenchymal stem cells (3% O₂ ; hypo-MSCs) in PLGA-based bio-artificial beds for subsequent subcutaneous islet transplantation. Sheet-typed polymeric PLGA scaffolds coated with hypo-MSCs or normo-MSCs (MSCs cultured under normoxia conditions, 21% O₂ ) were implanted subcutaneously in mice.

RESULTS

Compared to normo-MSCs, hypo-MSCs significantly enhanced vasculogenesis, both on the interior and exterior surfaces of the implanted PLGA devices, which peaked 4 weeks after implantation. Further, infusion of porcine islets inside the prevascularized PLGA bed restored normal glycemic control in 6 of 6 STZ-induced diabetic mice. The mass of the marginal islet was approximately 2000 IEQs, which is comparable to that required for the renal subcapsular space, a highly vascularized site.

CONCLUSIONS

Therefore, PLGA-based bio-artificial devices prevascularized with hypo-MSCs could be a useful modality for successful subcutaneous islet transplantation, which is of high clinical relevance.

Adipose-derived stem-cell-implanted poly(ϵ-caprolactone)/chitosan scaffold improves bladder regeneration in a rat model

AIM

The study investigated the feasibility of seeding adipose-derived stem cells (ASCs) onto a poly(ϵ-caprolactone)/chitosan (PCL/CS) scaffold for bladder reconstruction using a rat model of bladder augmentation.

MATERIALS & METHODS

In the experimental group, the autologous ASCs were seeded onto the PCL/CS scaffold for bladder augmentation. An unseeded scaffold was used for bladder augmentation as control group. The sham group was also set.

RESULT

8 weeks after implantation, more densely smooth muscles were detected in the experimental group with a larger bladder capacity and more intensive blood vessels. Immunofluorescence staining demonstrated that some of the smooth muscle cells were transdifferentiated from the ASCs.

CONCLUSION

Our findings indicated that ASC-seeded PCL/CS may be a potential scaffold for bladder tissue engineering.

Preconditioning influences mesenchymal stem cell properties in vitro and in vivo

Various diseases and toxic factors easily impair cellular and organic functions in mammals. Organ transplantation is used to rescue organ function, but is limited by scarce resources. Mesenchymal stem cell (MSC)-based therapy carries promising potential in regenerative medicine because of the self-renewal and multilineage potency of MSCs; however, MSCs may lose biological functions after isolation and cultivation for a long time in vitro. Moreover, after they are injected in vivo and migrate into the damaged tissues or organs, they encounter a harsh environment coupled with death signals due to the inadequate tensegrity structure between the cells and matrix. Preconditioning, genetic modification and optimization of MSC culture conditions are key strategies to improve MSC functions in vitro and in vivo, and all of these procedures will contribute to improving MSC transplantation efficacy in tissue engineering and regenerative medicine. Preconditioning with various physical, chemical and biological factors is possible to preserve the stemness of MSCs for further application in studies and clinical tests. In this review, we mainly focus on preconditioning and the corresponding mechanisms for improving MSC activities in vitro and in vivo; we provide a glimpse into the promotion of MSC-based cell therapy development for regenerative medicine. As a promising consequence, MSC transplantation can be applied for the treatment of some terminal diseases and can prolong the survival time of patients in the near future.

Targeting Murine Mesenchymal Stem Cells to Kidney Injury Molecule-1 Improves Their Therapeutic Efficacy in Chronic Ischemic Kidney Injury

Mesenchymal stem cells (MSC) have been experimentally used for kidney repair, but modest retention limits their efficacy. Cell‐surface coating allows modulating MSC homing and interaction with target cells. We coated mouse adipose tissue‐derived MSC with antibodies directed against kidney injury molecule‐1 (ab‐KIM1), which is upregulated in injured kidneys, and tested the hypothesis that this would enhance their therapeutic effects in ischemic kidney injury. Untreated MSC, ab‐KIM1‐coated MSC (KIM‐MSC), or vehicle, were injected systemically into the carotid artery of 2‐kidneys, 1‐clip mice 2 weeks after surgery. MSC retention in different organs was explored 24 hours, 48 hours, or 2 weeks after injection. Renal volume, perfusion, and oxygenation were studied 2 weeks after injection using magnetic resonance imaging in vivo, and renal inflammation, apoptosis, capillary density, and fibrosis ex vivo. The ab‐KIM1 coating had little effect on MSC viability or proliferation. The stenotic kidney showed upregulated KIM1 expression, selective homing, and greater retention of KIM‐MSC compared to untreated MSC and compared to other organs. KIM‐MSC‐injected mice improved renal perfusion and capillary density, and attenuated oxidative damage, apoptosis, and fibrosis compared to mice treated with vehicle or with native MSC. In conclusion, MSC coating with ab‐KIM1 increased their retention in the ischemic kidney and enhanced their therapeutic efficacy. This novel method may be useful to selectively target injured kidneys, and supports further development of strategies to enhance cell‐based treatment of ischemic kidney injury. Stem Cells Translational Medicine2018;7:394–403

The biological changes of umbilical cord mesenchymal stem cells in inflammatory environment induced by different cytokines

Mesenchymal stem cells (MSCs) are used as therapeutic tool for the treatment of immune diseases. The inflammatory environment also influences the characteristics of MSCs after transplantation. The aim of the study was to investigate the effects of pro-inflammatory cytokines on the characteristics of umbilical cord mesenchymal stem cells (UCMSCs). UCMSCs were exposed to pro-inflammatory cytokines in vitro for 3 and 7 days, and the biological properties were analyzed. The results showed that the proliferation ability was suppressed by interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β). The adipogenic capacity was inhibited in all conditioned medium, while the chondrogenic and osteogenic capacity was enhanced by TNF-α and IL-1β in vitro. Prostaglandin E2 (PGE2) was increased by IL-1β on the third day, and angiopoietin-1 (Ang-1) was inhibited appreciably by TNF-α on the seventh day. Interleukin-6 (IL-6) was increased by TNF-α and IL-1β, and hepatocyte growth factor (HGF) was inhibited by all inflammatory cytokines. IFN-γ secretion level from human peripheral mononuclear cells (hPBMCs) was lowered by UCMSCs which had been stimulated by TNF-α or IL-1β for 3 days. Moreover, IFN-γ and TNF-α secretion level was only inhibited by UCMSCs which had been by stimulated IFN-γ for 3 days but not 7 days. Our data demonstrated that different inflammatory cytokines and the duration of treatment had different effects on the properties of UCMSCs, which might be instructive for clinical pretreatment in cellular therapeutics.

Treatment of diabetes mellitus-induced erectile dysfunction using endothelial progenitor cells genetically modified with human telomerase reverse transcriptase

The efficacy of treatments for diabetes mellitus-induced erectile dysfunction (DMED) is quite poor, and stem cell therapy is emerging as a useful method. In this study, we used endothelial progenitor cells (EPCs) overexpressing human telomerase reverse transcriptase (hTERT) for the treatment of DMED. Rat EPCs were transfected with hTERT (EPCs-hTERT). EPCs-hTERT secreted more growth factors and demonstrated enhanced proliferation and resistance to oxidative stress. Twenty-four male DMED rats were subjected to four treatments: DMED (DMED group), EPCs (EPCs group), EPCs transduced with control lentivirus (EPC-control group) and EPCs-hTERT (EPCs-hTERT group). A group of healthy rats were used as the normal control group. The erectile function in the EPCs-hTERT group was markedly increased compared with the EPCs and EPCs-control groups. The EPCs-hTERT group exhibited more growth factors, smooth muscle content and retained stem cells in penile tissues. The degree of apoptosis and collagen/smooth muscle ratio in penile tissues of the EPCs-hTERT group was considerably reduced. Endothelial nitric oxide synthase (eNOS) expression increased significantly in the EPCs-hTERT group. Taken together, these data showed that the enhanced paracrine effect, resistance to oxidative stress and proliferation of EPCs-hTERT may contribute to the improvements of erectile function in DMED rats.

Activation of the NGF/TrkA signaling pathway attenuates diabetic erectile dysfunction

Erectile dysfunction (ED) is a common complication of diabetes mellitus (DM). The exact role of the NGF/TrkA signaling pathway in the pathogenesis of diabetic ED is largely unknown. In the present study, we investigated the role of the NGF/TrkA signaling pathway in Sprague-Dawley rats with diabetic ED. Animals were divided into 2 groups: the normal group and the DM ED model group. The model group included the blank subgroup, the negative control (NC) subgroup, the TrkA subgroup and the TrkA + NGF subgroup. Erectile function, intracavernous pressure (ICP) and mean arterial pressure were measured respectively. Immunohistochemistry was used to examine the number of neuronal nitric oxide synthase (nNOS) expressing nerve fibers. The quantitative real-time polymerase chain reaction was applied to detect the mRNA expressions of NGF and TrkA in the cavernous tissue. Further, Western blotting was conducted to detect the expressions of NGF, TrkA and its downstream ERK pathway-related proteins. Higher erectile frequency, ICP values and diastolic function, more nNOS-positive nerve fibers, and decreased systolic function of the corpus cavernosum smooth muscle were found in the TrkA and TrkA+NGF groups when compared with the blank and the NC groups. Moreover, significantly higher mRNA expressions of NGF and TrkA, and upregulated protein expressions of NGF, TrkA, c-raf, ERK1/2 and CREB1 were found in the TrkA and the TrkA + NGF groups. In conclusion, downregulation in the NGF/TrkA signaling pathway may contribute to the pathogenesis of diabetic ED.

[Treatment by stem cell therapy of erectile dysfunction of diabetic origin: State of the art]

PURPOSE

Review of various publications on stem cell therapy to treat erectile dysfunction of diabetic origin.

MATERIAL AND METHODS

Bibliographic search in PUBMED performed using the keywords cell therapy strain/erectile dysfunction associated with diabetes. Among the 51 articles obtained from the PUBMED research, we selected 16 articles for their specificity of studying erectile dysfunction (DE) related to diabetes.

RESULTS

Different types of stem cells have been studied: adipose derived mesenchymal stem cells/bone marrow derived mesenchymal stem cells as well as progenitor endothelial cells. The experimental protocols are quite similar from one study to the next with nevertheless some specifications concerning the studied cells and the monitoring of the latter. Intracavernous pressure (ICP) measured after the injection of stem cells into the corpus cavernosum was always significantly higher than the control populations. The addition of certain growth factors to stem cells by gene transfection improve the efficacy of the cells. No ideal tracking markers of the cells have been identified.

CONCLUSION

The positive effect of the injection of stem cells on the ICP belongs to the cellular trans-differentiation effect but especially to the paracrine effects which have not yet been completely elucidated.

Hypoxia-induced activin A diminishes endothelial cell vasculogenic activity

Acute ischaemia causes a significant loss of blood vessels leading to deterioration of organ function. Multiple ischaemic conditions are associated with up‐regulation of activin A, but its effect on endothelial cells (EC) in the context of hypoxia is understudied. This study evaluated the role of activin A in vasculogenesis in hypoxia. An in vitro vasculogenesis model, in which EC were cocultured with adipose stromal cells (ASC), was used. Incubation of cocultures at 0.5% oxygen led to decrease in EC survival and vessel density. Hypoxia up‐regulated inhibin B_A (monomer of activin A) mRNA by 4.5‐fold and activin A accumulation in EC‐conditioned media by 10‐fold, but down‐regulated activin A inhibitor follistatin by twofold. Inhibin B_A expression was also increased in human EC injected into ischaemic mouse muscles. Activin A secretion was positively modulated by hypoxia mimetics dimethyloxalylglycine and desferrioxamine. Silencing HIF1α or HIF2α expression decreased activin A secretion in EC exposed to hypoxia. Introduction of activin A to cocultures decreased EC number and vascular density by 40%; conversely, blockade of activin A expression in EC or its activity improved vasculogenesis in hypoxia. Activin A affected EC survival directly and by modulating ASC paracrine activity leading to diminished ability of the ASC secretome to support EC survival and vasculogenesis. In conclusion, hypoxia up‐regulates EC secretion of activin A, which, by affecting both EC and adjacent mesenchymal cells, creates a micro‐environment unfavourable for vasculogenesis. This finding suggests that blockade of activin A signalling in ischaemic tissue may improve preservation of the affected tissue.

Hypoxia enhances the therapeutic potential of superparamagnetic iron oxide-labeled adipose-derived stem cells for myocardial infarction

Adipose-derived stem cells (ASCs) induce therapeutic angiogenesis due to pro-angiogenic cytokines secretion. Superparamagnetic iron oxide (SPIO) nanoparticles are critical for magnetic resonance (MR) tracking of implanted cells. Hypoxia is a powerful stimulus for angiogenic activity of ASCs. In this study, we investigated whether therapeutic potency could be enhanced by implantation of hypoxia-preconditioned SPIO-labeled ASCs (_SPIOASCs) into the infarcted myocardium. ASCs and _SPIOASCs were cultured under 2% O₂ (hypoxia) or 95% air (normoxia). Cells were intramyocardially injected into the infarcted myocardium after 48-h culture. We found that hypoxia culture increased the mRNA expression of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) in ASCs and _SPIOASCs. The VEGF protein in the conditioned medium was significantly higher in hypoxic ASCs and _SPIOASCs than in normoxic ASCs and _SPIOASCs. The capillary density and left ventricular contractile function in the infarcted myocardium were significantly higher 4 weeks after implantation with hypoxic ASCs and _SPIOASCs than with normoxic ASCs and _SPIOASCs. Improvement in the capillary density and left ventricle function didn't differ between hypoxic ASCs-transplanted rats and hypoxic _SPIOASCs-transplanted rats. Hypoxic culture enhanced the angiogenic efficiency of ASCs. It was concluded that implantation of hypoxic ASCs or _SPIOASCs promotes therapeutic angiogenesis and cardiac function recovery in the infarcted myocardium. SPIO labeling does not impact the beneficial effect of hypoxic ASCs.

Visualizing changes in brain-derived neurotrophic factor (BDNF) expression using bioluminescence imaging in living mice

Brain-derived neurotrophic factor (BDNF) plays a fundamental role in expressing various neural functions including memory consolidation. Alterations of BDNF levels in the brain are associated with neurodegenerative and neuropsychiatric disorders. Therefore, it is important to understand how levels of BDNF are controlled. Recently we generated a novel transgenic mouse strain, termed the Bdnf-Luciferase transgenic (Bdnf-Luc Tg) mouse, to monitor changes in Bdnf expression. In the present study, we detected the bioluminescence signal from living Bdnf-Luc Tg mice after intraperitoneal administration of d-luciferin. Despite high levels of Bdnf expression in the brain, it was difficult to detect a signal from the brain region, probably because of its poorly penetrable (short-wavelength) bioluminescence. However, we could detect the changes in the bioluminescence signal in the brain region using a luciferin analogue generating a near-infrared wavelength of bioluminescence. We also found a strong correlation between increases in body weight and bioluminescence signal in the abdominal region of Tg mice fed a high-fat diet. These results show that changes in Bdnf expression can be visualized using living mice, and that the Tg mouse could be a powerful tool for clarification of the role of Bdnf expression in pathophysiological and physiological conditions.

Adipose tissue-derived stem cell therapy for erectile dysfunction in rats: a systematic review and meta-analysis

OBJECTIVE

We aimed to systematically assess the effect of adipose tissue-derived stem cell (ADSC) therapy and its influential factors on the treatment of erectile dysfunction (ED) in rats.

METHODS

Two authors independently searched for published studies through PubMed and EMBASE from study inception until August 31, 2016. A meta-analysis was used to combine the effect estimate from the published studies. A subgroup analysis was performed to identify the effect of some influential factors. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated by a fixed-effects or random-effects model analysis.

RESULTS

Twenty studies with a total of 248 rats were included in this meta-analysis. The pooled analysis showed that ADSC therapy significantly increased the ratio of intracavernous pressure and mean arterial pressure (ICP/MAP; SMD 3.46, 95% CI 2.85-4.06; P < 0.001) compared to control therapy. The levels of neuronal nitric oxide synthase (nNOS; SMD 6.37, 95% CI 4.35-8.39; P < 0.001), the cavernous smooth muscle content (CSMC; SMD 3.65, 95% CI 2.65-4.65; P < 0.001), the ratio of cavernous smooth muscle and collagen (CSM/collagen; SMD 4.16, 95% CI 2.59-5.72; P < 0.001), and the cyclic guanosine monophosphate (cGMP; SMD 7.12, 95% CI 2.76-11.48; P = 0.001) were higher following ADSC therapy than following control therapy. Subgroup analysis showed that ADSCs modified by growth or neurotrophic factors significantly recovered erectile function (P < 0.001) compared with ADSC therapy.

CONCLUSION

The adequate data indicated that ADSC therapy recovered erectile function and regenerated cavernous structures in ED rats, and ADSCs modified by some growth and neurotrophic factors accelerated the recovery of erectile function and cavernous structures in ED rats.

Combination of mesenchymal stem cell injection with icariin for the treatment of diabetes-associated erectile dysfunction

The present study was aimed to examine whether icariin, a traditional Chinese medicine, could improve therapeutic effects of adipose derived mesenchymal stem cells (ADSCs) for diabetes-associated erectile dysfunction (DMED). DMED were induced in rats by intraperitoneal injection of streptozotocin and confirmed by erectile function measurement. Then, rats of diabetic ED were randomly divided to receive the treatment of saline, ADSCs, icariin or ADSCs combined with icariin respectively. Compared with the treatment by ADSCs or icariin alone, intracavernosum injection of ADSCs combined with the following daily gastric gavage of icariin significantly augmented the value of ICP and ICP/MAP (p<0.01). Meanwhile, the survival of transplanted ADSCs was much improved due to the application of icariin. Similarly, immunofluorescent staining analysis demonstrated that the improved erectile tissue structure by combination of ADSCs and icariin was significantly associated with the increased expression of endothelial markers (vWF) (p<0.01) and smooth muscle markers (α-SMA) (p<0.01). Furthermore, the structure changes in corpus cavernosum were further confirmed by the Masson’s trichrome staining. To explore the possible mechanism underlying icariin-enhanced therapeutic efficacy of MSCs, we employed an in vitro testing system by introducing H₂O₂ to imitate oxidative stress condition considering the oxidative environment faced by engrafted ADSCs and anti-oxidative capacity of icariin_.In vitro, we found that the addition of icariin considerably reduced the apoptosis of ADSCs, and attenuated the intracellular reactive oxygen species (ROS), the superoxidase dismutase (SOD) activity and the lactate dehydrogenase (LDH). Subsequently, we examined the expression of apoptosis-related proteins and explored the potential signaling pathway through which icariin promoted the survival of ADSCs against oxidative stress. It was demonstrated that icariin significantly inhibited the upregulation of apoptosis-related proteins under oxidative condition, including Bax and cleaved caspase-3, while promoted the expression of anti-apoptotic factor BCL2. These effects were accompanied with the activation of signal molecules, PI3K/Akt and STAT3. The further signal protein inhibition assays exhibited that the suppression of STAT3 abrogated the icariin-mediated anti-apoptotic effects observed above, while did not influence the expression of PI3K/Akt. However, PI3K inhibition could abrogate icariin–mediated STAT3 activation and achieved a similar effect as STAT3 inhibition. Our results suggested that icariin was an effective adjuvant for enhancing ADSC-based therapy of DMEM, which may be ascribed to their protection of ADSCs against oxidative stress via the regulation of PI3K/Akt-STAT3 signal pathway.

Erythropoietin Modification Enhances the Protection of Mesenchymal Stem Cells on Diabetic Rat-Derived Schwann Cells: Implications for Diabetic Neuropathy

Diabetes-triggered apoptosis of Schwann cells (SC) contributes to the degradation of diabetic peripheral neuropathy (DNP). In recent years, mesenchymal stem cells (MSC) were applied to DPN repair and it was demonstrated that paracrine secretion played a key role in neuroprotection exerted by MSC. Erythropoietin (EPO) is a potent cytokine capable of reducing apoptosis of SC. However, the expression of EPO in MSC is limited. In this study, we hypothesized that overexpression of EPO in MSC (EPO-MSC) may significantly improve their neuroprotective potentials. The EPO overexpression in MSC was achieved by lentivirus transduction. SC derived from the periphery nerve of diabetic rats were cocultured with MSC or EPO-MSC in normal or high glucose culture condition, respectively. In normal glucose culture condition, the overexpression of EPO in MSC promoted the MSC-induced restoration of SC from diabetic rats, including increases in GSH level and cell viability, decrease in TUNEL apoptosis, upregulation of antiapoptotic proteins, p-Akt, and Bcl-2, and downregulation of proapoptotic proteins, cleaved caspase-3, and Bax. The subsequent results in high glucose culture condition showed similar promotions achieved by EPO-MSC. Thus, it could be concluded that EPO-MSC possessed a potent potential in hampering apoptosis of SC, and the suppression was probably attributed to attenuating oxidative stress and regulating apoptosis related protein factors.

Combination of low-energy shock-wave therapy and bone marrow mesenchymal stem cell transplantation to improve the erectile function of diabetic rats

Stem cell transplantation and low-energy shock-wave therapy (LESWT) have emerged as potential and effective treatment protocols for diabetic erectile dysfunction. During the tracking of transplanted stem cells in diabetic erectile dysfunction models, the number of visible stem cells was rather low and decreased quickly. LESWT could recruit endogenous stem cells to the cavernous body and improve the microenvironment in diabetic cavernous tissue. Thus, we deduced that LESWT might benefit transplanted stem cell survival and improve the effects of stem cell transplantation. In this research, 42 streptozotocin-induced diabetic rats were randomized into four groups: the diabetic group (n = 6), the LESWT group (n = 6), the bone marrow-derived mesenchymal stem cell (BMSC) transplantation group (n = 15), and the combination of LESWT and BMSC transplantation group (n = 15). One and three days after BMSC transplantation, three rats were randomly chosen to observe the survival numbers of BMSCs in the cavernous body. Four weeks after BMSC transplantation, the following parameters were assessed: the surviving number of transplanted BMSCs in the cavernous tissue, erectile function, real-time polymerase chain reaction, and penile immunohistochemical assessment. Our research found that LESWT favored the survival of transplanted BMSCs in the cavernous body, which might be related to increased stromal cell-derived factor-1 expression and the enhancement of angiogenesis in the diabetic cavernous tissue. The combination of LESWT and BMSC transplantation could improve the erectile function of diabetic erectile function rats more effectively than LESWT or BMSC transplantation performed alone.

Overexpression of Heme Oxygenase-1 in Mesenchymal Stem Cells Augments Their Protection on Retinal Cells In Vitro and Attenuates Retinal Ischemia/Reperfusion Injury In Vivo against Oxidative Stress

Retinal ischemia/reperfusion (I/R) injury, involving several ocular diseases, seriously threatens human ocular health, mainly treated by attenuating I/R-induced oxidative stress. Currently, mesenchymal stem cells (MSCs) could restore I/R-injured retina through paracrine secretion. Additionally, heme oxygenase-1 (HO-1) could ameliorate oxidative stress and thus retinal apoptosis, but the expression of HO-1 in MSC is limited. Here, we hypothesized that overexpression of HO-1 in MSC (MSC-HO-1) may significantly improve their retina-protective potentials. The overexpression of HO-1 in MSC was achieved by lentivirus transduction. Then, MSC or MSC-HO-1 was cocultured with retinal ganglion cells (RGC-5) in H₂O₂-simulated oxidative condition and their protection on RGC-5 was systemically valuated in vitro. Compared with MSC, MSC-HO-1 significantly attenuated H₂O₂-induced injury of RGC-5, including decrease in cellular ROS level and apoptosis, activation of antiapoptotic proteins p-Akt and Bcl-2, and blockage of proapoptotic proteins cleaved caspase 3 and Bax. In retinal I/R rats model, compared with control MSC, MSC-HO-1-treated retina significantly retrieved its structural thickness, reduced cell apoptosis, markedly attenuated retinal oxidative stress level, and largely regained the activities of typical antioxidant enzymes, SOD and CAT. Therefore, it could be concluded that overexpression of HO-1 provides a promising strategy to enhance the MSC-based therapy for I/R-related retinal injury.

Stem Cells in Male Sexual Dysfunction: Are We Getting Somewhere?

INTRODUCTION

Stem cells for sexual disorders are steadily being introduced into clinical trials. Two conditions of importance are the main target for this line of treatment, especially when regarding the wide array of translational and basic science highlighting the potential advantages of regenerative therapy: erectile dysfunction (ED) and more recently Peyronie disease (PD). Cellular therapy offers a treatment modality that might reverse disease progression. It would be used in a curative setting, in contrast to other pharmaceutical agents that are currently available.

AIM

To review basic preclinical studies and recent clinical trials of stem cells on ED and PD.

METHODS

A search of the medical literature for the following terms was performed using PubMed: stem cells, cellular therapy, erectile dysfunction, Peyronie's disease, and clinical trial.

MAIN OUTCOME MEASURES

A non-systematic narrative review and critical reflection on preclinical and clinical studies administering stem cells for ED and PD in animal models and human subjects.

RESULTS

Numerous studies have confirmed the beneficial functional effects of stem cell injection in established animal models on ED and PD. Various stem cell types have been adopted, from embryonic to adult mesenchymal cell types. Each cell type offers distinctive advantages and disadvantages. Diverse administrations of stem cells were investigated, with insignificant variability in the ultimate results. Stem cells appear to have a pronounced paracrine effect, rather than the classic engraftment and differentiation hypothesis. Phase 1 clinical trials using stem cells have not reported any severe adverse events in animals. However, these results cannot be extrapolated to draw any conclusions about efficacy in human patients.

CONCLUSION

Stem cells have an established efficacy in preclinical studies and early clinical trials. Studies are currently being published demonstrating the safety of intrapenile injection of autologous bone marrow- and adipose tissue-derived stem cells. Soebadi MA, Milenkovic U, Weyne E, et al. Stem Cells in Male Sexual Dysfunction: Are We Getting Somewhere? Sex Med Rev 2017;5:222-235.

Advances in stem cell research for the treatment of male sexual dysfunctions

PURPOSE OF REVIEW

To summarize recent literature on basic stem cell research in erectile dysfunction in cavernous nerve injury, aging, diabetes, and Peyronie's disease and to provide a perspective on clinical translation of these cellular therapies.

RECENT FINDINGS

Stem cell research has been concentrated on mesenchymal stem (stromal) cells from bone marrow and adipose tissue. Application of both cell types has produced positive effects on erectile function in various animal models of erectile dysfunction. In acute animal models, such as cavernous nerve injury-induced erectile dysfunction and chemically induced Peyronie's disease, engraftment and differentiation have not been observed, and stem cells are believed to interact with the host tissue in a paracrine fashion, whereas in chronic disease models some evidence suggests both engraftment and paracrine factors may support improved function. Clinical trials are now investigating therapeutic efficacy of cellular therapy, whereas the first safety studies in humans have recently been published.

SUMMARY

Evidence from preclinical studies has established stem cells as a potential curative treatment for erectile dysfunction and early phase clinical trials are currently performed.

Antioxidative mechanism of Lycium barbarum polysaccharides promotes repair and regeneration following cavernous nerve injury

Polysaccharides extracted from Lycium barbarum exhibit antioxidant properties. We hypothesized that these polysaccharides resist oxidative stress-induced neuronal damage following cavernous nerve injury. In this study, rat models were intragastrically administered Lycium barbarum polysaccharides for 2 weeks at 1, 7, and 14 days after cavernous nerve injury. Serum superoxide dismutase and glutathione peroxidase activities significantly increased at 1 and 2 weeks post-injury. Serum malondialdehyde levels decreased at 2 and 4 weeks. At 12 weeks, peak intracavernous pressure, the number of myelinated axons and nicotinamide adenine dinucleotide phosphate-diaphorase-positive nerve fibers, levels of phospho-endothelial nitric oxide synthase protein and 3-nitrotyrosine were higher in rats administered at 1 day post-injury compared with rats administered at 7 and 14 days post-injury. These findings suggest that application of Lycium barbarum polysaccharides following cavernous nerve crush injury effectively promotes nerve regeneration and erectile functional recovery. This neuroregenerative effect was most effective in rats orally administered Lycium barbarum polysaccharides at 1 day after cavernous nerve crush injury.

Two complementary strategies to improve cell engraftment in mesenchymal stem cell-based therapy: Increasing transplanted cell resistance and increasing tissue receptivity

Over the past 2 decades, therapies based on mesenchymal stem cells (MSC) have been tested to treat several types of diseases in clinical studies, due to their potential for tissue repair and regeneration. Currently, MSC-based therapy is considered a biologically safe procedure, with the therapeutic results being very promising. However, the benefits of these therapies are not stable in the long term, and the final outcomes manifest with high inter-patient variability. The major cause of these therapeutic limitations results from the poor engraftment of the transplanted cells. Researchers have developed separate strategies to improve MSC engraftment. One strategy aims at increasing the survival of the transplanted MSCs in the recipient tissue, rendering them more resistant to the hostile microenvironment (cell-preconditioning). Another strategy aims at making the damaged tissue more receptive to the transplanted cells, favoring their interactions (tissue-preconditioning). In this review, we summarize several approaches using these strategies, providing an integral and updated view of the recent developments in MSC-based therapies. In addition, we propose that the combined use of these different conditioning strategies could accelerate the process to translate experimental evidences from pre-clinic studies to the daily clinical practice.