Dopamine regulates mobilization of mesenchymal stem cells during wound angiogenesis

Possible Association Between Dopamine Antagonists and Increased Conversion to Exudative Age-Related Macular Degeneration

Purpose: To investigate whether modulating dopamine signaling affects conversion to exudative age-related macular degeneration (AMD). Methods: A retrospective cohort study was performed using the Duke Epic database. Eyes from patients with a diagnosis of nonexudative AMD with at least 1 year of follow-up were evaluated for conversion to exudative AMD. Eyes with an AMD diagnosis were evaluated for age, sex, smoking history, hypertension, Age-Related Eye Disease Study (AREDS) or AREDS2 prescription, dopamine-modulating therapy prescription, and indication for dopamine-modulating therapy. Generalized estimating equations were used to calculate odds ratios for individual variables on conversion from nonexudative to exudative AMD. Results: Five hundred fifty-eight eyes of 354 patients with an initial diagnosis of nonexudative AMD were evaluated for conversion to exudative AMD. Conversion to exudative AMD was significantly higher in patients who had been on dopamine antagonist therapies for at least 3 years than in patients who were not on any dopamine-modulating therapies. After controlling for other variables, dopamine antagonists were associated with an increased risk for conversion to exudative AMD at 3 years of follow-up (P = .005). Conclusions: These findings suggest that antagonizing dopamine signaling may be associated with the development of macular neovascularization in eyes with nonexudative AMD. Although the data are observational, these findings warrant further investigation of dopamine signaling in conversion to exudative AMD.

The neuroprotective potential of curcumin on T. Spiralis infected mice

BACKGROUND

Trichinella spiralis can affect the brain by inducing inflammatory and vascular changes. Drug management with the antiparasitic drug albendazole can be enhanced by natural compounds such as curcumin. The potential benefit of curcumin as an adjuvant to albendazole in the management of cerebral affection during experimental T. spiralis infection was evaluated. Animals received either curcumin 150 mg/Kg, albendazole 50 mg/Kg or a combination of both drugs. Animal groups receiving treatment were compared with infected and non-infected control groups. Blood levels of reduced glutathione (GSH) and dopamine were measured, and brain tissue expression of cyclooxygenase-2 enzyme (COX-2) and CD34 was assessed by immunohistochemistry.

RESULTS

T. spiralis infection resulted in a state of oxidative stress, which was improved by albendazole and curcumin. Also, both drugs restored the peripheral dopamine level, which was decreased in infected non-treated mice. Curcumin was also found to be efficient in improving brain pathology and reducing local COX-2 and CD 34 expression.

CONCLUSIONS

Inflammatory and pathological changes during neurotrichinosis can be improved by the addition of curcumin to conventional anti-parasitic drugs.

Dopamine signaling from ganglion cells directs layer-specific angiogenesis in the retina

During central nervous system (CNS) development, a precisely patterned vasculature emerges to support CNS function. How neurons control angiogenesis is not well understood. Here, we show that the neuromodulator dopamine restricts vascular development in the retina via temporally limited production by an unexpected neuron subset. Our genetic and pharmacological experiments demonstrate that elevating dopamine levels inhibits tip-cell sprouting and vessel growth, whereas reducing dopamine production by all retina neurons increases growth. Dopamine production by canonical dopaminergic amacrine interneurons is dispensable for these events. Instead, we found that temporally restricted dopamine production by retinal ganglion cells (RGCs) modulates vascular development. RGCs produce dopamine precisely during angiogenic periods. Genetically limiting dopamine production by ganglion cells, but not amacrines, decreases angiogenesis. Conversely, elevating ganglion-cell-derived dopamine production inhibits early vessel growth. These vasculature outcomes occur downstream of vascular endothelial growth factor receptor (VEGFR) activation and Notch-Jagged1 signaling. Jagged1 is increased and subsequently inhibits Notch signaling when ganglion cell dopamine production is reduced. Our findings demonstrate that dopaminergic neural activity from a small neuron subset functions upstream of VEGFR to serve as developmental timing cue that regulates vessel growth.

Effects of Dopamine on stem cells and its potential roles in the treatment of inflammatory disorders: a narrative review

Inflammation is the host's protective response against harmful external stimulation that helps tissue repair and remodeling. However, excessive inflammation seriously threatens the patient's life. Due to anti-inflammatory effects, corticosteroids, immunosuppressants, and monoclonal antibodies are used to treat various inflammatory diseases, but drug resistance, non-responsiveness, and severe side effect limit their development and application. Therefore, developing other alternative therapies has become essential in anti-inflammatory therapy. In recent years, the in-depth study of stem cells has made them a promising alternative drug for the treatment of inflammatory diseases, and the function of stem cells is regulated by a variety of signals, of which dopamine signaling is one of the main influencing factors. In this review, we review the effects of dopamine on various adult stem cells (neural stem cells, mesenchymal stromal cells, hematopoietic stem cells, and cancer stem cells) and their signaling pathways, as well as the application of some critical dopamine receptor agonists/antagonists. Besides, we also review the role of various adult stem cells in inflammatory diseases and discuss the potential anti-inflammation function of dopamine receptors, which provides a new therapeutic target for regenerative medicine in inflammatory diseases.

Immunomodulatory effect of dopamine in human keratinocytes and macrophages under chronical bisphenol-A exposure conditions

Dopamine is a key neurotransmitter that links the nervous and the immune system. Bisphenol A (BPA) is an endocrine disruptor with a wide distribution in the environment that is used in the manufacturing of plastic products. Evidence shows that BPA can interfere with the central dopaminergic transmission; however, there are no previous reports of this effect outside the central nervous system. Thus, the aim of this work was to investigate the in vitro mechanisms of action involved in the response to dopamine in both human keratinocyte and macrophage cell lines chronically exposed to BPA. Dopamine modulates cytokine secretion and NF-κB expression in BPA-treated HaCaT keratinocytes, without modifying these parameters in BPA-treated THP-1 macrophages. In addition, dopamine increases MMP activity in both BPA-treated cell lines, although it decreases keratinocytes migration. We suggest the immunomodulatory effect of dopamine might be different in keratinocytes and macrophages under chronical BPA exposure conditions. These findings revealed for the first time the in vitro immunomodulatory effect of dopamine in the presence of BPA at peripheral level.

Role of neurotransmitters in the regulation of cutaneous wound healing

Wound healing is a highly coordinated and dynamic process of tissue repair after injury. The global burden of disease associated with wounds, both acute and chronic, is a significantly rising health concern. Upon skin wounding, neurons have the ability to sense the disruption to mediate the release of neurotransmitters into the wound microenvironment. Serotonin that has long been recognised as a potential vasoconstrictor is now also being contemplated to play a role in re-epithelialisation of wounds. While the role of neuropeptides in stimulating diabetic wound healing is being increasingly emphasised, on the other hand, dopamine is being widely studied for its dual role in mediating both pro- and antiangiogenic effects at the site of the wounds. Similarly, epinephrine levels that are known to be elevated during stress is now recognised as a contributing factor towards delayed wound closure, thereby serving as an inhibitor of wound healing. Thus, each neurotransmitter regulates wound repair and their active regeneration in a typical way. Strengthening our understanding of the molecular pathways via which the neurotransmitter modulates the immune system to control wound healing can yield potential therapeutic measures. Further investigations regarding the safety, efficacy, and cost-effectiveness of these processes are a prerequisite for their possible translation into clinical trials.

Effect of nimodipine combined with fasudil on vascular endothelial function and inflammatory factors in patients with cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is an acute disease with rapid progression and critical condition. The most common complication of aSAH is cerebral vasospasm (CVS). Patients are predisposed to severe cerebral ischemia, brain injury, or even death if effective measures are not taken in time to relieve symptoms. This study mainly determines the effect of nimodipine (NM) combined with fasudil on vascular endothelial function (VEF) and inflammatory factors (IFs) in patients with aSAH induced CVS.

METHODS

The clinical data of 77 patients with aSAH induced CVS treated in the Renmin Hospital of Wuhan University from March 2019 to June 2020 were analyzed retrospectively. Based on different drug therapies, patients receiving NM monotherapy were assigned to the control group (n=32), while those treated with NM combined with fasudil were included in the observation group (n=45), both received two consecutive weeks of treatment. The two arms were compared regarding the following items: clinical efficacy, average blood flow velocities (BFVs) of anterior, posterior and middle cerebral arteries, serum IFs, levels of vascular endothelial growth factor (VEGF), ET-1 and CGRP, cognitive function (Montreal Cognitive Assessment Scale, MOCA), activities of daily living (Bathel index), and adverse reactions.

RESULTS

The overall response rate of the observation group was significantly higher than that of the control group (P<0.05). After treatment, the BFVs of the anterior, posterior and middle cerebral arteries in the observation group decreased significantly compared with the control group (P<0.05). ET-1 and VEGF decreased in both groups, while CGRP increased, with more significant changes in the observation group (P<0.05). Serum IFs reduced in both arms, with more evident reductions in the observation group (P<0.05). The MOCA score and Barthel index increased statistically in both arms and were higher in the observation group compared with the control group (P<0.05). There was no significant difference in the total incidence of adverse reactions between the observation group and the control group (P>0.05).

CONCLUSIONS

NM combined with fasudil in the treatment of aSAH induced CVS can effectively improve the VEF, alleviate IFs, and enhance the cognitive function and quality of life of patients, which is worth popularizing in clinic.

Quinagolide Treatment Reduces Invasive and Angiogenic Properties of Endometrial Mesenchymal Stromal Cells

Endometrial mesenchymal stromal cells (E-MSCs) extensively contribute to the establishment and progression of endometrial ectopic lesions through formation of the stromal vascular tissue, and support to its growth and vascularization. As E-MSCs lack oestrogen receptors, endometriosis eradication cannot be achieved by hormone-based pharmacological approaches. Quinagolide is a non-ergot-derived dopamine receptor 2 agonist reported to display therapeutic effects in in vivo models of endometriosis. In the present study, we isolated E-MSCs from eutopic endometrial tissue and from ovarian and peritoneal endometriotic lesions, and we tested the effect of quinagolide on their proliferation and matrix invasion ability. Moreover, the effect of quinagolide on E-MSC endothelial differentiation was assessed in an endothelial co-culture model of angiogenesis. E-MSC lines expressed dopamine receptor 2, with higher expression in ectopic than eutopic ones. Quinagolide inhibited the invasive properties of E-MSCs, but not their proliferation, and limited their endothelial differentiation. The abrogation of the observed effects by spiperone, a dopamine receptor antagonist, confirmed specific dopamine receptor activation. At variance, no involvement of VEGFR2 inhibition was observed. Moreover, dopamine receptor 2 activation led to downregulation of AKT and its phosphorylation. Of interest, several effects were more prominent on ectopic E-MSCs with respect to eutopic lines. Together with the reported effects on endometrial and endothelial cells, the observed inhibition of E-MSCs may increase the rationale for quinagolide in endometriosis treatment.

Mesenchymal stem cells in cancer progression and anticancer therapeutic resistance

Increasing evidence indicates that the tumor microenvironment appears to play an increasingly important role in cancer progression and therapeutic resistance. Several types of cells within the tumor stroma had distinct impacts on cancer progression, either promoting or inhibiting cancer cell growth. Mesenchymal stem cells (MSCs) are a distinct type of cells that is linked to tumor development. MSCs are recognized for homing to tumor locations and promoting or inhibiting cancer cell proliferation, angiogenesis and metastasis. Moreover, emerging studies suggests that MSCs are also involved in therapeutic resistance. In this review, we analyzed the existing researches and elaborate on the functions of MSCs in cancer progression and anticancer therapeutic resistance, demonstrating that MSCs may be a viable cancer therapeutic target.

Proteomic and Biological Analysis of the Effects of Metformin Senomorphics on the Mesenchymal Stromal Cells

Senotherapeutics are new drugs that can modulate senescence phenomena within tissues and reduce the onset of age-related pathologies. Senotherapeutics are divided into senolytics and senomorphics. The senolytics selectively kill senescent cells, while the senomorphics delay or block the onset of senescence. Metformin has been used to treat diabetes for several decades. Recently, it has been proposed that metformin may have anti-aging properties as it prevents DNA damage and inflammation. We evaluated the senomorphic effect of 6 weeks of therapeutic metformin treatment on the biology of human adipose mesenchymal stromal cells (MSCs). The study was combined with a proteome analysis of changes occurring in MSCs' intracellular and secretome protein composition in order to identify molecular pathways associated with the observed biological phenomena. The metformin reduced the replicative senescence and cell death phenomena associated with prolonged in vitro cultivation. The continuous metformin supplementation delayed and/or reduced the impairment of MSC functions as evidenced by the presence of three specific pathways in metformin-treated samples: 1) the alpha-adrenergic signaling, which contributes to regulation of MSCs physiological secretory activity, 2) the signaling pathway associated with MSCs detoxification activity, and 3) the aspartate degradation pathway for optimal energy production. The senomorphic function of metformin seemed related to its reactive oxygen species (ROS) scavenging activity. In metformin-treated samples, the CEBPA, TP53 and USF1 transcription factors appeared to be involved in the regulation of several factors (SOD1, SOD2, CAT, GLRX, GSTP1) blocking ROS.

Catecholamines in the regulation of angiogenesis in cutaneous wound healing

Angiogenesis involves the formation of new blood vessels from preexisting ones, and it is an essential step during cutaneous wound healing, which supports cells at the wound site with nutrition and oxygen. Impaired angiogenesis in the wound tissues results in delayed wound closure and healing. Among the regulators of angiogenesis, the role of catecholamines (epinephrine, norepinephrine, and dopamine) is of interest due to their diverse roles in the process of wound healing. While both norepinephrine and epinephrine mostly inhibit the angiogenic process in cutaneous wounds, dopamine, the other member of the catecholamine family, has interesting and contradictory roles in the regulation of angiogenesis in the wound beds, depending on the type of dopamine receptor involved. The stimulation of dopamine D2 receptors negatively regulates the angiogenic process in normal dermal wounds and thereby delays healing, whereas the stimulation of dopamine D1 receptors promotes angiogenesis and expedites healing in diabetic wounds. Importantly, catecholamines also play important roles in other pathological conditions, and specific agonists and antagonists of catecholamines are available for the treatment of some disorders. Therefore, such drugs may be utilized for the management of angiogenesis to promote the healing of dermal wounds. This review provides a broad overview of the angiogenic process during cutaneous wound healing and the regulatory roles played by catecholamines during the process.

Investigation mechanisms between normal, developing and regenerating livers for regenerative liver drug design

Aim: A systematic multimolecule drug design procedure is proposed for promoting hepatogenesis and liver regeneration. Materials & methods: Genome-wide microarray data including three hepatic conditions are obtained from the GEO database (GSE15238). System modeling and big data mining methods are used to construct real genome-wide genetic-and-epigenetic networks (GWGENs). Then, we extracted the core GWGENs by applying principal network projection on real GWGENs of normal, developing and regenerating livers, respectively. After that, we investigated the significant signal pathways and epigenetic modifications in the core GWGENs to identify potential biomarkers as drug targets. Result & conclusion: A multimolecule drug consisting of sulmazole, clofibrate, colchicine, furazolidone, nadolol, eticlopride and felbinac is proposed to target on novel biomarkers for promoting hepatogenesis and liver regeneration.

A Concise Review of the Conflicting Roles of Dopamine-1 versus Dopamine-2 Receptors in Wound Healing

Catecholamines play an important regulatory role in cutaneous wound healing. The exact role of dopamine in human epidermis has yet to be fully elucidated. Current published evidence describes its differential effects on two separate families of G protein coupled receptors: D1-like and D2-like dopamine receptors. Dopamine may enhance angiogenesis and wound healing through its action on dopamine D1 receptors, while impairing wound healing when activating D2 receptors. This review summarizes the evidence for the role of dopamine in wound healing and describes potential mechanisms behind its action on D1 versus D2-like receptors in the skin.

Dopaminergic enhancement of cellular adhesion in bone marrow derived mesenchymal stem cells (MSCs)

Dopamine (DA) is a well-known neurotransmitter and critical element in the mussel adhesive protein that has gained increasing attention for its role in cellular growth enhancement in biomaterials, including cellular adhesion improvement. As the mechanism underlying this remains unclear, the objective of this study was to explore the effects of DA on the adhesion properties of bone marrow derived rat mesenchymal stem cells (rMSCs) using an hydroxyapatite gelatin nanocomposite biomaterial and to test whether the effects are mediated through various endogenously expressed DA receptors. Primary rMSCs were pretreated with D1-like antagonist, D2-like antagonist, or a combination of these antagonists followed by treatment with 50 μM DA and cellular adhesion quantification at 0.5, 1, 2 and 4 hours post DA addition. DA was found to increase rMSC adhesion and spreading at the 0.5 hour time-point and the dopaminergic effect on cell adhesion was partially blocked by DA antagonists. In addition, the D1-like and D2-like antagonists appeared to have a similar effect on rMSCs. Immunofluorescent staining indicated that the rMSC spreading area was significantly increased in the DA treated group versus the control group. Treatment of the D1-like DA antagonists with DA revealed that the actin filaments of rMSCs could not connect the membrane with the nucleus. In summary, DA was found to enhance early rMSC adhesion partially via DA receptor activation.

Differential Response of Dopamine Mediated by β-Adrenergic Receptors in Human Keratinocytes and Macrophages: Potential Implication in Wound Healing

OBJECTIVE

Dopamine is an immunomodulatory neurotransmitter. In the skin, keratinocytes and macrophages produce proinflammatory cytokines and metalloproteinases (MMPs) which participate in wound healing. These cells have a catecholaminergic system that modulates skin pathophysiologic processes. We have demonstrated that dopamine modulates cytokine production in keratinocytes via dopaminergic and adrenergic receptors (ARs). The aim of this study was to evaluate the effect of dopamine and its interaction with β-ARs in human HaCaT keratinocytes and THP-1 macrophages. We evaluated the production of inflammatory mediators implicated in wound healing.

METHODS

Cells were stimulated with dopamine in the absence or presence of the β-adrenergic antagonist propranolol. Wound closure, MMP activity, and the production of IL-8, IL-1β, and IκB/NFκB pathway activation were determined in stimulated cells.

RESULTS

Dopamine did not affect the wound closure in human keratinocytes, but diminished the propranolol stimulatory effect, thus delaying cell migration. Similarly, dopamine significantly decreased MMP-9 activity and the propranolol-induced MMP activity. Dopamine significantly increased the p65-NFκB subunit levels in the nuclear extracts, which were reduced in the presence of propranolol in keratinocytes. On the other hand, dopamine significantly increased MMP-9 activity in THP-1 macrophages, but did not modify the propranolol-increased enzymatic activity. Dopamine significantly increased IL-8 production in human macrophages, an effect that was partially reduced by propranolol. Dopamine did not modify the p65-NFκB levels in the nuclear extracts in THP-1 macrophages.

CONCLUSION

We suggest that the effect of dopamine via β-ARs depends on the physiological condition and the cell type involved, thus contributing to either improve or interfere with the healing process.

Activation of D2 Dopamine Receptors in CD133+ve Cancer Stem Cells in Non-small Cell Lung Carcinoma Inhibits Proliferation, Clonogenic Ability, and Invasiveness of These Cells

Lung carcinoma is the leading cause of cancer-related death worldwide, and among this cancer, non-small cell lung carcinoma (NSCLC) comprises the majority of cases. Furthermore, recurrence and metastasis of NSCLC correlate well with CD133+ve tumor cells, a small population of tumor cells that have been designated as cancer stem cells (CSC). We have demonstrated for the first time high expression of D₂ dopamine (DA) receptors in CD133+ve adenocarcinoma NSCLC cells. Also, activation of D₂ DA receptors in these cells significantly inhibited their proliferation, clonogenic ability, and invasiveness by suppressing extracellular signal-regulated kinases 1/2 (ERK1/2) and AKT, as well as down-regulation of octamer-binding transcription factor 4 (Oct-4) expression and matrix metalloproteinase-9 (MMP-9) secretion by these cells. These results are of significance as D₂ DA agonists that are already in clinical use for treatment of other diseases may be useful in combination with conventional chemotherapy and radiotherapy for better management of NSCLC patients by targeting both tumor cells and stem cell compartments in the tumor mass.

Dopamine receptor type 2 (DRD2) inhibits migration and invasion of human tumorous pituitary cells through ROCK-mediated cofilin inactivation

Non-functioning pituitary tumors (NFPTs) frequently present local invasiveness. Dopamine receptor 2 (DRD2) agonists are the only medical therapy that induces tumor shrinkage in some patients. Invasion requires cytoskeleton rearrangements that are tightly regulated by cofilin pathway, whose alterations correlate with invasion in different tumors. We investigated the effect of DR2D agonist on NFPT cells migration/invasion and the molecular mechanisms involved. We demonstrated that DRD2 agonist reduced migration (-44 ± 25%, p < 0.01) and invasion (-34 ± 6%, p < 0.001) and increased about 4-fold Ser3-phosphorylated inactive cofilin (P-cofilin) in NFPT cells. These effects were abolished by inhibiting ROCK, a kinase that phosphorylates cofilin. The overexpression of wild-type or phosphodeficient S3A-cofilin increased HP75 cells migration (+49 ± 6% and +57 ± 9% vs empty vector, respectively, p < 0.05), while phosphomimetic mutant had no effect. Interestingly, P-cofilin levels were lower in invasive vs non-invasive tumors by both western blot (mean P-cofilin/total cofilin ratio 0.77 and 1.93, respectively, p < 0.05) and immunohistochemistry (mean percentage of P-cofilin positive cells 17.6 and 45.7, respectively, p < 0.05). In conclusion, we showed that the invasiveness of pituitary tumors is promoted by the activation of cofilin, which can be regulated by DRD2 and might represent a novel biomarker for pituitary tumors' invasive behavior.

Dopamine mobilizes mesenchymal progenitor cells through D2-class receptors and their PI3K/AKT pathway

As the nervous system exerts direct and indirect effects on stem cells mobilization and catecholamines mobilize hematopoietic stem cells, we hypothesized that dopamine might induce mesenchymal progenitor cells (MPCs) mobilization. We show that dopamine induced in vitro MPCs migration through D2-class receptors, and their alternative phosphoinositide 3-kinase/Akt pathways. Also, administration of catecholamines induced in vivo mobilization of colony-forming unit-fibroblast in mice. In contrast, in vitro and in vivo MPCs migration was suppressed by D2-class receptors antagonists and blocking antibodies, consistent with dopamine signaling pathway implication. In humans, patients treated with L-dopa or catecholaminergic agonists showed a significant increase of a MPC-like population (CD45-CD31-CD34-CD105+) in their peripheral blood. These findings reveal a new link between catecholamines and MPCs mobilization and suggest the potential use of D2-class receptors agonists for mobilization of MPCs in clinical settings.

mRNA and protein expression of the angiogenesis-related genes EDIL3, AMOT and ECM1 in mesenchymal stem cells in psoriatic dermis

BACKGROUND

Dermal microvasculature expansion and angiogenesis are prominent in psoriasis. Our previous microarray study showed that the angiogenesis-related genes EDIL3 (epidermal growth factor-like repeats and discoidin I-like domains 3), AMOT (angiomotin) and ECM1 (extracellular matrix protein 1), had high expression levels in dermal mesenchymal stem cells (DMSCs) from psoriatic skin lesions.

AIM

To investigate the mRNA and protein expressions of EDIL3, AMOT and ECM1 in DMSCs derived from psoriatic skin in order to better determine the molecular mechanisms of angiogenesis in the skin.

METHODS

DMSCs from 12 patients with psoriasis and 14 healthy controls (HCs) were cultured to passage 3, and identified by morphology, immunophenotype and multipotential differentiation. The mRNA and protein expressions of EDIL3, AMOT, and ECM1 in the DMSCs were determined using real-time reverse transcription PCR and western blotting.

RESULTS

DMSCs displayed spindle-like morphology and surface protein expression, and were able to differentiate into osteoblasts, chondrocytes and adipocytes. mRNA expression analysis showed that EDIL3, AMOT and ECM1 were expressed at 2.54-fold, 2.11-fold, and 1.90-fold higher levels, respectively, in psoriatic DMSCs compared with HC DMSCs (all P < 0.05). Protein analysis showed significantly (all P < 0.01) higher concentrations of EDIL3, AMOT and ECM1in the psoriasis group than in the HC group.

CONCLUSIONS

Our data demonstrate for the first time that expression of EDIL3, AMOT and ECM1 is altered in DMSCs in psoriasis, suggesting that EDIL3, AMOT and ECM1 are involved in the excessive angiogenesis and vasodilation observed in psoriasis.

Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats

Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs.

Poly(Dopamine)-Assisted Immobilization of Xu Duan on 3D Printed Poly(Lactic Acid) Scaffolds to Up-Regulate Osteogenic and Angiogenic Markers of Bone Marrow Stem Cells

Three-dimensional printing is a versatile technique to generate large quantities of a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized 3D printed poly(lactic acid) (PLA) scaffolds and use a mussel-inspired surface coating and Xu Duan (XD) immobilization to regulate cell adhesion, proliferation and differentiation of human bone-marrow mesenchymal stem cells (hBMSCs). We prepared PLA scaffolds and coated with polydopamine (PDA). The chemical composition and surface properties of PLA/PDA/XD were characterized by XPS. PLA/PDA/XD controlled hBMSCs' responses in several ways. Firstly, adhesion and proliferation of hBMSCs cultured on PLA/PDA/XD were significantly enhanced relative to those on PLA. In addition, the focal adhesion kinase (FAK) expression of cells was increased and promoted cell attachment depended on the XD content. In osteogenesis assay, the osteogenesis markers of hBMSCs cultured on PLA/PDA/XD were significantly higher than seen in those cultured on a pure PLA/PDA scaffolds. Moreover, hBMSCs cultured on PLA/PDA/XD showed up-regulation of the ang-1 and vWF proteins associated with angiogenic differentiation. Our results demonstrate that the bio-inspired coating synthetic PLA polymer can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to direct the specific responses of hBMSCs.

Dopamine and serotonin regulate tumor behavior by affecting angiogenesis

The biogenic amines dopamine and serotonin are neurotransmitters and hormones, which are mainly produced in the central nervous system and in the gastro-intestinal tract. They execute local and systemic functions such as intestinal motility and tissue repair. Dopamine and serotonin are primarily stored in and transported by platelets. This review focuses on the recently recognized role of dopamine and serotonin in the regulation of tumor behavior by affecting angiogenesis and tumor cell proliferation. Preclinical studies demonstrate that dopamine inhibits tumor growth via activation of dopamine receptor D2 on endothelial and tumor cells. Serotonin stimulates tumor growth via activation of serotonin receptor 2B on endothelial cells and serotonin receptors on tumor cells. Drugs that stimulate dopamine receptor D2 or inhibit serotonin receptors are available and therefore clinical intervention studies for cancer patients are within reach.

The role of catecholamines in mesenchymal stem cell fate

Mesenchymal stem cells (MSCs) are multipotent stem cells found in many adult tissues, especially bone marrow (BM) and are capable of differentiation into various lineage cells such as osteoblasts, adipocytes, chondrocytes and myocytes. Moreover, MSCs can be mobilized from connective tissue into circulation and from there to damaged sites to contribute to regeneration processes. MSCs commitment and differentiation are controlled by complex activities involving signal transduction through cytokines and catecholamines. There has been an increasing interest in recent years in the neural system, functioning in the support of stem cells like MSCs. Recent efforts have indicated that the catecholamine released from neural and not neural cells could be affected characteristics of MSCs. However, there have not been review studies of most aspects involved in catecholamines-mediated functions of MSCs. Thus, in this review paper, we will try to describe the current state of catecholamines in MSCs destination and discuss strategies being used for catecholamines for migration of these cells to damaged tissues. Then, the role of the nervous system in the induction of osteogenesis, adipogenesis, chondrogenesis and myogenesis from MSCs is discussed. Recent progress in studies of signaling transduction of catecholamines in determination of the final fate of MSCs is highlighted. Hence, the knowledge of interaction between MSCs with the neural system could be applied towards the development of new diagnostic and treatment alternatives for human diseases.

The emerging use of bone marrow-derived mesenchymal stem cells in the treatment of human chronic wounds

INTRODUCTION

Close to 5 million people in the USA are affected by chronic wounds, and billions of dollars are spent annually for their treatment. Despite advances in chronic wound management over the past decades, many patients afflicted with chronic wounds fail to heal or their ulcers recur. There is emerging evidence that the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) can offset this situation of impaired healing.

AREAS COVERED

This article provides a review of the use of BM-MSC for the treatment of chronic wounds, the current development of stem cell delivery to chronic wounds and related challenges are also described in this manuscript.

EXPERT OPINION

Numerous animal studies and a few pilot studies in human wounds have shown that BM-MSC can augment wound closure. Still, the primary contribution of mesenchymal stem cells (MSCs) to cutaneous regeneration and the long-term systemic effects of MSCs are yet to be established. In addition, we need to determine whether other types of stem/progenitor cells will be more effective. Therefore, more randomized controlled clinical trials need to be undertaken. It is of importance to remember that even with the most advanced and sophisticated therapeutic approaches, proper wound care and adherence to basic principles remain critical.

Repeated immobilization stress induces catecholamine production in rat mesenteric adipocytes

Catecholamines (CATs), the major regulator of lipolysis in adipose tissue, are produced mainly by the sympathoadrenal system. However, recent studies report endogenous CAT production in adipocytes themselves. This study investigated the effects of single and repeated (7-14 times) immobilization (IMO) stress on CAT production in various fat depots of the rat. Single IMO quickly induced a rise of norepinephrine (NE) and epinephrine (EPI) concentration in mesenteric and brown adipose depots. Adaptive response to repeated IMO included robust increases of NE and EPI levels in mesenteric and subcutaneous adipose tissue. These changes likely reflect the activation of sympathetic nervous system in fat depots by IMO. However, this process was also paralleled by an increase in tyrosine hydroxylase gene expression in mesenteric fat, suggesting regulation of endogenous CAT production in adipose tissue cells. Detailed time-course analysis (time course 10, 30, and 120 min) clearly showed that repeated stress led to increased CAT biosynthesis in isolated mesenteric adipocytes resulting in gradual accumulation of intracellular EPI during IMO exposure. Comparable changes were also found in stromal/vascular fractions, with more pronounced effects of single than repeated IMO. The potential physiological importance of these findings is accentuated by parallel increase in expression of vesicular monoamine transporter 1, indicating a need for CAT storage in adipocyte vesicles. Taken together, we show that CAT production occurs in adipose tissue and may be activated by stress directly in adipocytes.

The role of mesenchymal stem cells in anti-cancer drug resistance and tumour progression

It is becoming increasingly clear that the tumour microenvironment has a very important role in tumour progression and drug resistance. Many different cell types within the tumour stroma have an effect on tumour progression either in a positive or in a negative way. Mesenchymal stem cells (MSCs) are a distinct population of cells that have been linked with tumour growth. Mesenchymal stem cells can home to tumours where they modulate the immune system and facilitate tumour growth, angiogenesis and metastasis. Recent studies have shown that MSCs also have an important role in the resistance to various anti-cancer drugs. This mini-review provides an overview of the functional properties of MSCs in tumour progression and drug resistance.

Mesenchymal stem cells in tumor development: emerging roles and concepts

Mesenchymal stem cells (MSCs) are multipotent progenitor cells that participate in the structural and functional maintenance of connective tissues under normal homeostasis. They also act as trophic mediators during tissue repair, generating bioactive molecules that help in tissue regeneration following injury. MSCs serve comparable roles in cases of malignancy and are becoming increasingly appreciated as critical components of the tumor microenvironment. MSCs home to developing tumors with great affinity, where they exacerbate cancer cell proliferation, motility, invasion and metastasis, foster angiogenesis, promote tumor desmoplasia and suppress anti-tumor immune responses. These multifaceted roles emerge as a product of reciprocal interactions occurring between MSCs and cancer cells and serve to alter the tumor milieu, setting into motion a dynamic co-evolution of both tumor and stromal tissues that favors tumor progression. Here, we summarize our current knowledge about the involvement of MSCs in cancer pathogenesis and review accumulating evidence that have placed them at the center of the pro-malignant tumor stroma.