Paracrine action mediate the antifibrotic effect of transplanted mesenchymal stem cells in a rat model of global heart failure

Cell Therapies in Cardiomyopathy: Current Status of Clinical Trials

Because the human heart has limited potential for regeneration, the loss of cardiomyocytes during cardiac myopathy and ischaemic injury can result in heart failure and death. Stem cell therapy has emerged as a promising strategy for the treatment of dead myocardium, directly or indirectly, and seems to offer functional benefits to patients. The ideal candidate donor cell for myocardial reconstitution is a stem-like cell that can be easily obtained, has a robust proliferation capacity and a low risk of tumour formation and immune rejection, differentiates into functionally normal cardiomyocytes, and is suitable for minimally invasive clinical transplantation. The ultimate goal of cardiac repair is to regenerate functionally viable myocardium after myocardial infarction (MI) to prevent or heal heart failure. This review provides a comprehensive overview of treatment with stem-like cells in preclinical and clinical studies to assess the feasibility and efficacy of this novel therapeutic strategy in ischaemic cardiomyopathy.

Therapeutic effect of mesenchymal stem cells on experimentally induced hypertensive cardiomyopathy in adult albino rats

Hypertensive heart diseases affect millions of people worldwide. We aimed to investigate the hypertensive left ventricular histological changes and assess the effectiveness of bone marrow derived mesenchymal stem cells (MSCs) therapy in the treatment of hypertensive cardiomyopathy. Adult male albino rats were assigned into two groups: group I (control), group II (Experimental) subdivided into subgroup IIa (hypertensive) and subgroup IIb (stem cell therapy). Left ventricles (LVs) were processed for light and electron microscope. Mallory's trichrome and immunostaining for caspase-3 and desmin were carried out. Hypertension caused left ventricular histological and immunohistochemical changes that had been effectively improved by MSCs therapy.

Paracrine Effects of Adipose-Derived Stem Cells on Matrix Stiffness-Induced Cardiac Myofibroblast Differentiation via Angiotensin II Type 1 Receptor and Smad7

Human mesenchymal stem cells (hMSCs) hold great promise in cardiac fibrosis therapy, due to their potential ability of inhibiting cardiac myofibroblast differentiation (a hallmark of cardiac fibrosis). However, the mechanism involved in their effects remains elusive. To explore this, it is necessary to develop an in vitro cardiac fibrosis model that incorporates pore size and native tissue-mimicking matrix stiffness, which may regulate cardiac myofibroblast differentiation. In the present study, collagen coated polyacrylamide hydrogel substrates were fabricated, in which the pore size was adjusted without altering the matrix stiffness. Stiffness is shown to regulate cardiac myofibroblast differentiation independently of pore size. Substrate at a stiffness of 30 kPa, which mimics the stiffness of native fibrotic cardiac tissue, was found to induce cardiac myofibroblast differentiation to create in vitro cardiac fibrosis model. Conditioned medium of hMSCs was applied to the model to determine its role and inhibitory mechanism on cardiac myofibroblast differentiation. It was found that hMSCs secrete hepatocyte growth factor (HGF) to inhibit cardiac myofibroblast differentiation via downregulation of angiotensin II type 1 receptor (AT₁R) and upregulation of Smad7. These findings would aid in establishment of the therapeutic use of hMSCs in cardiac fibrosis therapy in future.

Biology and biogenesis of shed microvesicles

The ability of cells to transmit bioactive molecules to recipient cells and the extracellular environment is a fundamental requirement for both normal physiology and disease pathogenesis. It has traditionally been thought that soluble factors released from cells were responsible for this cellular signaling but recent research has revealed a fundamental role for microvesicles in this process. Microvesicles are heterogeneous membrane-bound sacs that are shed from the surface of cells into the extracellular environment in a highly regulated process. They are shed following the selective incorporation of a host of molecular cargo including multiple types of proteins and nucleic acids. In addition to providing new insight into the etiology of complex human diseases, microvesicles also show great promise as a tool for advanced diagnosis and therapy as we move forward into a new age of personalized medicine. Here we review current status of the rapidly evolving field of microvesicle biology, highlighting critical regulatory roles for several small GTPases in the biology and biogenesis of shed microvesicles.

Adipose tissue-derived stem cells suppress hypertrophic scar fibrosis via the p38/MAPK signaling pathway

BACKGROUND

Hypertrophic scars (HS) generally occur after injury to the deep layers of the dermis, resulting in functional deficiency for patients. Growing evidence has been identified that the supernatant of adipose tissue-derived stem cells (ADSCs) significantly ameliorates fibrosis of different tissues, but limited attention has been paid to its efficacy on attenuating skin fibrosis. In this study, we explored the effect and possible mechanism of ADSC-conditioned medium (ADSC-CM) on HS.

METHOD

Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting were used to detect the expression of collagen I (Col1), collagen III (Col3), and α-smooth muscle actin (α-SMA) after fibroblasts and cultured HS tissues were stimulated with ADSC-CM and p38 inhibitor/activator. Immunofluorescence staining was performed to test the expression of α-SMA. Masson's trichrome staining, hematoxylin and eosin (H&E) staining, and immunohistochemistry staining were carried out to assess the histological and pathological change of collagen in the BALB/c mouse excisional model. All data were analyzed by using SPSS17.0 software. Statistical analysis was performed by Student's t tests.

RESULTS

The in vitro and ex vivo study revealed ADSC-CM decreased the expression of Col1, Col3, and α-SMA. Together, thinner and orderly arranged collagen was manifested in HS tissues cultured with ADSC-CM. Dramatically, the assessed morphology showed an accelerated healing rate, less collagen deposition, and col1- and col3-positive cells in the ADSC-CM treated group. Importantly, the protein level of p-p38 was downregulated in a concentration-dependent manner in HS-derived fibroblasts with ADSC-CM treatment, which further decreased the expression of p-p38 after the application of its inhibitor, SB203580. SB203580 led to an obvious decline in the expression of Col1, Col3, and α-SMA in fibroblasts and cultured HS tissues and presented more ordered arrangement and thinner collagen fibers in BALB/c mice. Lastly, anisomycin, an agonist of p38, upregulated the expression of fibrotic proteins and revealed more disordered structure and denser collagen fibers.

CONCLUSION

This study demonstrated that ADSC-CM could decrease collagen deposition and scar formation in in vitro, ex vivo and in vivo experiments. The regulation of the p38/MAPK signaling pathway played an important role in the process. The application of ADSC-CM may provide a novel therapeutic strategy for HS treatment, and the anti-scarring effect can be achieved by inhibition of the p38/MAPK signaling pathway.

Novel therapeutic strategies targeting fibroblasts and fibrosis in heart disease

Our understanding of the functions of cardiac fibroblasts has moved beyond their roles in heart structure and extracellular matrix generation and now includes their contributions to paracrine, mechanical and electrical signalling during ontogenesis and normal cardiac activity. Fibroblasts also have central roles in pathogenic remodelling during myocardial ischaemia, hypertension and heart failure. As key contributors to scar formation, they are crucial for tissue repair after interventions including surgery and ablation. Novel experimental approaches targeting cardiac fibroblasts are promising potential therapies for heart disease. Indeed, several existing drugs act, at least partially, through effects on cardiac connective tissue. This Review outlines the origins and roles of fibroblasts in cardiac development, homeostasis and disease; illustrates the involvement of fibroblasts in current and emerging clinical interventions; and identifies future targets for research and development.

Will stem cells bring hope to pathological skin scar treatment?

Pathological skin scars, such as keloids, aesthetically and psychosocially affect patients. The quest for scar reduction and the increasing recognition of patient satisfaction has led to the continued exploration of scar treatment. Stem cells are a promising source for tissue repair and regeneration. The multi-potency and secretory functions of these cells could offer possible treatments for pathological scars and have been examined in recent studies. Here, we analyze the factors that influence the formation of pathological skin scars, summarize recent research on pathological scar treatment with stem cells and elaborate on the possible mechanisms of this treatment. Additionally, other effects of stem cell treatments are also presented while evaluating potential side effects of stem cell-based pathological scar treatments. Thus, this review may provide meaningful guidance in the clinic for scar treatments with stem cells.

Netrin-1 promotes mesenchymal stem cell revascularization of limb ischaemia

This study examines the effect and mechanism of action of Netrin-1 on bone marrow mesenchymal stem cells in angiogenesis. Tube formation and migration of bone marrow mesenchymal stem cells were observed in cell culture. Bone marrow mesenchymal stem cells or Netrin-1-bone marrow mesenchymal stem cells were injected into the ischaemic area of the rat hind limb on the first day after surgery. Laser Doppler perfusion imaging was performed to analyse the levels of vascular endothelial growth factor in plasma and muscles, and immunohistochemistry and immunofluorescence were used to analyse angiogenesis. Bone marrow mesenchymal stem cells in medium containing Netrin-1 markedly increased the number of tubes formed and the migration of bone marrow mesenchymal stem cells compared with the untreated control group. The function of Netrin-1 in tube formation and migration is similar to vascular endothelial growth factor, and combined with vascular endothelial growth factor, Netrin-1 has more enhanced effect than in the other three groups. The Netrin-1-bone marrow mesenchymal stem cell group had better augmented blood-perfusion scores and vessel densities, as well as improved function of the ischaemic limb than that of the group injected with bone marrow mesenchymal stem cells (treated with bone marrow mesenchymal stem cells individually) or the control group (treated with medium). These results suggest that Netrin-1 has the ability to augment the angiogenesis of bone marrow mesenchymal stem cells and improve the function of the ischaemic hind limb by increasing the level of vascular endothelial growth factor.

Tracking and Therapeutic Value of Human Adipose Tissue-derived Mesenchymal Stem Cell Transplantation in Reducing Venous Neointimal Hyperplasia Associated with Arteriovenous Fistula

PURPOSE

To determine if adventitial transplantation of human adipose tissue-derived mesenchymal stem cells (MSCs) to the outflow vein of B6.Cg-Foxn1(nu)/J mice with arteriovenous fistula (AVF) at the time of creation would reduce monocyte chemoattractant protein-1 (Mcp-1) gene expression and venous neointimal hyperplasia. The second aim was to track transplanted zirconium 89 ((89)Zr)-labeled MSCs serially with positron emission tomography (PET) for 21 days.

MATERIALS AND METHODS

All animal experiments were performed according to protocols approved by the institutional animal care and use committee. Fifty B6.Cg-Foxn1(nu)/J mice were used to accomplish the study aims. Green fluorescent protein was used to stably label 2.5 × 10(5) MSCs, which were injected into the adventitia of the outflow vein at the time of AVF creation in the MSC group. Eleven mice died after AVF placement. Animals were sacrificed on day 7 after AVF placement for real-time polymerase chain reaction (n = 6 for MSC and control groups) and histomorphometric (n = 6 for MSC and control groups) analyses and on day 21 for histomorphometric analysis only (n = 6 for MSC and control groups). In a separate group of experiments (n = 3), animals with transplanted (89)Zr-labeled MSCs were serially imaged with PET for 3 weeks. Multiple comparisons were performed with two-way analysis of variance, followed by the Student t test with post hoc Bonferroni correction.

RESULTS

In vessels with transplanted MSCs compared with control vessels, there was a significant decrease in Mcp-1 gene expression (day 7: mean reduction, 62%; P = .029), with a significant increase in the mean lumen vessel area (day 7: mean increase, 176% [P = .013]; day 21: mean increase, 415% [P = .011]). Moreover, this was accompanied by a significant decrease in Ki-67 index (proliferation on day 7: mean reduction, 81% [P = .0003]; proliferation on day 21: mean reduction, 60%, [P = .016]). Prolonged retention of MSCs at the adventitia was evidenced by serial PET images of (89)Zr-labeled cells.

CONCLUSION

Adventitial transplantation of MSCs decreases Mcp-1 gene expression, accompanied by a reduction in venous neointimal hyperplasia.

Intralesional injection of adipose-derived stem cells reduces hypertrophic scarring in a rabbit ear model

INTRODUCTION

Redundant collagen deposition at sites of healing dermal wounds results in hypertrophic scars. Adipose-derived stem cells (ADSCs) exhibit promise in a variety of anti-fibrosis applications by attenuating collagen deposition. The objective of this study was to explore the influence of an intralesional injection of ADSCs on hypertrophic scar formation by using an established rabbit ear model.

METHODS

Twelve New Zealand albino rabbits were equally divided into three groups, and six identical punch defects were made on each ear. On postoperative day 14 when all wounds were completely re-epithelialized, the first group received an intralesional injection of ADSCs on their right ears and Dulbecco's modified Eagle's medium (DMEM) on their left ears as an internal control. Rabbits in the second group were injected with conditioned medium of the ADSCs (ADSCs-CM) on their right ears and DMEM on their left ears as an internal control. Right ears of the third group remained untreated, and left ears received DMEM. We quantified scar hypertrophy by measuring the scar elevation index (SEI) on postoperative days 14, 21, 28, and 35 with ultrasonography. Wounds were harvested 35 days later for histomorphometric and gene expression analysis.

RESULTS

Intralesional injections of ADSCs or ADSCs-CM both led to scars with a far more normal appearance and significantly decreased SEI (44.04 % and 32.48 %, respectively, both P <0.01) in the rabbit ears compared with their internal controls. Furthermore, we confirmed that collagen was organized more regularly and that there was a decreased expression of alpha-smooth muscle actin (α-SMA) and collagen type Ι in the ADSC- and ADSCs-CM-injected scars according to histomorphometric and real-time quantitative polymerase chain reaction analysis. There was no difference between DMEM-injected and untreated scars.

CONCLUSIONS

An intralesional injection of ADSCs reduces the formation of rabbit ear hypertrophic scars by decreasing the α-SMA and collagen type Ι gene expression and ameliorating collagen deposition and this may result in an effective and innovative anti-scarring therapy.

Paracrine action of mesenchymal stromal cells delivered by microspheres contributes to cutaneous wound healing and prevents scar formation in mice

BACKGROUND AIMS

Accumulating evidence suggests that mesenchymal stromal cells (MSCs) participate in wound healing to favor tissue regeneration and inhibit fibrotic tissue formation. However, the evidence of MSCs to suppress cutaneous scar is extremely rare, and the mechanism remains unidentified. This study aimed to demonstrate whether MSCs-as the result of their paracrine actions on damaged tissues-would accelerate wound healing and prevent cutaneous fibrosis.

METHODS

For efficient delivery of MSCs to skin wounds, microspheres were used to maintain MSC potency. Whether MSCs can accelerate wound healing and alleviate cutaneous fibrosis through paracrine action was investigated with the use of a Transwell co-culture system in vitro and a murine model in vivo.

RESULTS

MSCs cultured on gelatin microspheres fully retained their cell surface marker expression profile, proliferation, differentiation and paracrine potential. Co-cultures of MSCs and fibroblasts indicated that the benefits of MSCs on suppressing fibroblast proliferation and its fibrotic behavior induced by inflammatory cytokines probably were caused by paracrine actions. Importantly, microspheres successfully delivered MSCs into wound margins and significantly accelerated wound healing and concomitantly reduced the fibrotic activities of cells within the wounds and excessive accumulation of extracellular matrix as well as the transforming growth factor-β1/transforming growth factor-β3 ratio.

CONCLUSIONS

This study provides insight into what we believe to be a previously undescribed, multifaceted role of MSC-released protein in reducing cutaneous fibrotic formation. Paracrine action of MSCs delivered by microspheres may thus qualify as a promising strategy to enhance tissue repair and to prevent excessive fibrosis during cutaneous wound healing.

MSCs conditioned media and umbilical cord blood plasma metabolomics and composition

Human mesenchymal stem cells (hMSCs) from umbilical cord (UC) blood (UCB) and matrix are tested clinically for a variety of pathologies but in vitro expansion using culture media containing fetal bovine serum (FBS) is essential to achieve appropriate cell numbers for clinical use. Human UCB plasma (hUCBP) can be used as a supplement for hMSCs culture, since UCB is rich in soluble growth factors and due to worldwide increased number of cryopreserved UCB units in public and private banks, without the disadvantages listed for FBS. On the other hand, the culture media enriched in growth factors produced by these hMSCs in expansion (Conditioned medium--CM) can be an alternative to hMSCs application. The CM of the hMSCs from the UC might be a better therapeutic option compared to cell transplantation, as it can benefit from the local tissue response to the secreted molecules without the difficulties and complications associated to the engraftment of the allo- or xeno-transplanted cells. These facts drove us to know the detailed composition of the hUCBP and CM, by 1H-NMR and Multiplexing LASER Bead Technology. hUCBP is an adequate alternative for the FBS and the CM and hUCBP are important sources of growth factors, which can be used in MSCs-based therapies. Some of the major proliferative, chemotactic and immunomodulatory soluble factors (TGF-β, G-CSF, GM-CSF, MCP-1, IL-6, IL-8) were detected in high concentrations in CM and even higher in hUCBP. The results from 1H-NMR spectroscopic analysis of CM endorsed a better understanding of hMSCs metabolism during in vitro culture, and the relative composition of several metabolites present in CM and hUCBP was obtained. The data reinforces the potential use of hUCBP and CM in tissue regeneration and focus the possible use of hUCBP as a substitute for the FBS used in hMSCs in vitro culture.

Effects of Human Mesenchymal Stem Cells Isolated from Wharton's Jelly of the Umbilical Cord and Conditioned Media on Skeletal Muscle Regeneration Using a Myectomy Model

Skeletal muscle has good regenerative capacity, but the extent of muscle injury and the developed fibrosis might prevent complete regeneration. The in vivo application of human mesenchymal stem cells (HMSCs) of the umbilical cord and the conditioned media (CM) where the HMSCs were cultured and expanded, associated with different vehicles to induce muscle regeneration, was evaluated in a rat myectomy model. Two commercially available vehicles and a spherical hydrogel developed by our research group were used. The treated groups obtained interesting results in terms of muscle regeneration, both in the histological and in the functional assessments. A less evident scar tissue, demonstrated by collagen type I quantification, was present in the muscles treated with HMSCs or their CM. In terms of the histological evaluation performed by ISO 10993-6 scoring, it was observed that HMSCs apparently have a long-term negative effect, since the groups treated with CM presented better scores. CM could be considered an alternative to the in vivo transplantation of these cells, as it can benefit from the local tissue response to secreted molecules with similar results in terms of muscular regeneration. Searching for an optimal vehicle might be the key point in the future of skeletal muscle tissue engineering.

The study of fetal rat model of intra-amniotic isoproterenol injection induced heart dysfunction and phenotypic switch of contractile proteins

To establish a reliable isoproterenol induced heart dysfunction fetal rat model and understand the switches of contractile proteins, 45 pregnant rats were divided into 15 mg/kg-once, 15 mg/kg-twice, sham-operated once, sham-operated twice, and control groups. And 18 adult rats were divided into isoproterenol-treated and control groups. H&E staining, Masson staining, and transmission electron microscope were performed. Apoptotic rate assessed by TUNEL analysis and expressions of ANP, BNP, MMP-2, and CTGF of hearts were measured. Intra-amniotic injections of isoproterenol were supplied on E14.5 and E15.5 for fetuses and 7-day continuous intraperitoneal injections were performed for adults. Then echocardiography was performed with M-mode view assessment on E18.5 and 6 weeks later, respectively. Isoproterenol twice treated fetuses exhibited significant changes in histological evaluation, and mitochondrial damages were significantly severe with increased apoptotic rate. ANP and BNP increased and that of MMP-2 increased in isoproterenol twice treated group compared to control group, without CTGF. The isoforms transition of troponin I and myosin heavy chain of fetal heart dysfunction were opposite to adult procedure. The administration of intra-amniotic isoproterenol to fetal rats could induce heart dysfunction and the regulation of contractile proteins of fetuses was different from adult procedure.

Polysaccharide-based strategies for heart tissue engineering

Polysaccharides are abundant biomolecules in nature presenting important roles in a wide variety of living systems processes. Considering the structural and biological functions of polysaccharides, their properties have raised interest for tissue engineering. Herein, we described the latest advances in cardiac tissue engineering mediated by polysaccharides. We reviewed the data already obtained in vitro and in vivo in this field with several types of polysaccharides. Cardiac injection, intramyocardial in situ polymerization strategies, and scaffold-based approaches involving polysaccharides for heart tissue engineering are thus discussed.

Transplantation of mesenchymal stem cells promotes tissue regeneration in a glaucoma model through laser-induced paracrine factor secretion and progenitor cell recruitment

Among bone marrow cells, hematopoietic and mesenchymal components can contribute to repair damaged organs. Such cells are usually used in acute diseases but few options are available for the treatment of chronic disorders. In this study, we have used a laser-induced model of open angle glaucoma (OAG) to evaluate the potential of bone marrow cell populations and the mechanisms involved in tissue repair. In addition, we investigated laser-induced tissue remodeling as a method of targeting effector cells into damaged tissues. We demonstrate that among bone marrow cells, mesenchymal stem cells (MSC) induce trabecular meshwork regeneration. MSC injection into the ocular anterior chamber leads to far more efficient decrease in intraocular pressure (IOP) (p < .001) and healing than hematopoietic cells. This robust effect was attributable to paracrine factors from stressed MSC, as injection of conditioned medium from MSC exposed to low but not to normal oxygen levels resulted in an immediate decrease in IOP. Moreover, MSC and their secreted factors induced reactivation of a progenitor cell pool found in the ciliary body and increased cellular proliferation. Proliferating cells were observed within the chamber angle for at least 1 month. Laser-induced remodeling was able to target MSC to damaged areas with ensuing specific increases in ocular progenitor cells. Thus, our results identify MSC and their secretum as crucial mediators of tissue repair in OAG through reactivation of local neural progenitors. In addition, laser treatment could represent an appealing strategy to promote MSC-mediated progenitor cell recruitment and tissue repair in chronic diseases.

Cell-based therapy in lung regenerative medicine

Chronic lung diseases are becoming a leading cause of death worldwide. There are few effective treatments for those patients and less choices to prevent the exacerbation or even reverse the progress of the diseases. Over the past decade, cell-based therapies using stem cells to regenerate lung tissue have experienced a rapid growth in a variety of animal models for distinct lung diseases. This novel approach offers great promise for the treatment of several devastating and incurable lung diseases, including emphysema, idiopathic pulmonary fibrosis, pulmonary hypertension, and the acute respiratory distress syndrome. In this review, we provide a concise summary of the current knowledge on the attributes of endogenous lung epithelial stem/progenitor cells (EpiSPCs), mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) in both animal models and translational studies. We also describe the promise and challenges of tissue bioengineering in lung regenerative medicine. The therapeutic potential of MSCs is further discussed in IPF and chronic obstructive pulmonary diseases (COPD).

Mechanisms of therapeutic activity of multipotent cells in heart diseases

Analysis of our findings and published reports on possible mechanisms of therapeutic activity of stem/progenitor cell transplantation in cardiovascular pathologies is presented.

Human umbilical cord tissue-derived mesenchymal stromal cells attenuate remodeling after myocardial infarction by proangiogenic, antiapoptotic, and endogenous cell-activation mechanisms

Introduction

Among the plethora of cells under investigation to restore a functional myocardium, mesenchymal stromal cells (MSCs) have been granted considerable interest. However, whereas the beneficial effects of bone marrow MSCs (BM-MSCs) in the context of the diseased heart are widely reported, data are still scarce on MSCs from the umbilical cord matrix (UCM-MSCs). Herein we report on the effect of UCM-MSC transplantation to the infarcted murine heart, seconded by the dissection of the molecular mechanisms at play.

Methods

Human umbilical cord tissue-derived MSCs (UCX®), obtained by using a proprietary technology developed by ECBio, were delivered via intramyocardial injection to C57BL/6 females subjected to permanent ligation of the left descending coronary artery. Moreover, medium produced by cultured UCX® preconditioned under normoxia (CM) or hypoxia (CMH) was collected for subsequent in vitro assays.

Results

Evaluation of the effects upon intramyocardial transplantation shows that UCX® preserved cardiac function and attenuated cardiac remodeling subsequent to myocardial infarction (MI). UCX® further led to increased capillary density and decreased apoptosis in the injured tissue. In vitro, UCX®-conditioned medium displayed (a) proangiogenic activity by promoting the formation of capillary-like structures by human umbilical vein endothelial cells (HUVECs), and (b) antiapoptotic activity in HL-1 cardiomyocytes subjected to hypoxia. Moreover, in adult murine cardiac Sca-1⁺ progenitor cells (CPCs), conditioned medium enhanced mitogenic activity while activating a gene program characteristic of cardiomyogenic differentiation.

Conclusions

UCX® preserve cardiac function after intramyocardial transplantation in a MI murine model. The cardioprotective effects of UCX® were attributed to paracrine mechanisms that appear to enhance angiogenesis, limit the extent of the apoptosis, augment proliferation, and activate a pool of resident CPCs. Overall, these results suggest that UCX® should be considered an alternative cell source when designing new therapeutic approaches to treat MI.

Optimization of the cardiovascular therapeutic properties of mesenchymal stromal/stem cells-taking the next step

Despite current treatment options, cardiac failure is associated with significant morbidity and mortality highlighting a compelling clinical need for novel therapeutic approaches. Based on promising pre-clinical data, stem cell therapy has been suggested as a possible therapeutic strategy. Of the candidate cell types evaluated, mesenchymal stromal/stem cells (MSCs) have been widely evaluated due to their ease of isolation and ex vivo expansion, potential allogeneic utility and capacity to promote neo-angiogenesis and endogenous cardiac repair. However, the clinical application of MSCs for mainstream cardiovascular use is currently hindered by several important limitations, including suboptimal retention and engraftment and restricted capacity for bona fide cardiomyocyte regeneration. Consequently, this has prompted intense efforts to advance the therapeutic properties of MSCs for cardiovascular disease. In this review, we consider the scope of benefit from traditional plastic adherence-isolated MSCs and the lessons learned from their conventional use in preclinical and clinical studies. Focus is then given to the evolving strategies aimed at optimizing MSC therapy, including discussion of cell-targeted techniques that encompass the preparation, pre-conditioning and manipulation of these cells ex vivo, methods to improve their delivery to the heart and innovative substrate-directed strategies to support their interaction with the host myocardium.

Therapeutic vascular angiogenesis for intractable macroangiopathy-related digital ulcer in patients with systemic sclerosis: a pilot study

OBJECTIVE

SSc causes intractable ischaemic ulcers. To avoid major amputation, we examined the safety and efficacy of therapeutic vascular angiogenesis for digital ulcers due to SSc.

METHODS

A single-centre, open-label pilot study was conducted in patients with an ischaemic digital ulcer [n = 40, mean age 65 years (s.d. 8), Rutherford class III-5 or III-6) due to lcSSc (n = 11) or arteriosclerosis obliterans (ASO; n = 29). Bone marrow mononuclear cells (0.4-5.1 × 10(10) cells in total) were administered into the ischaemic limbs. We evaluated short-term safety and efficacy by means of a pain scale, (99m)Tc-tetrofosmin scintigraphy and transcutaneous oxygen tension (TcPO2) before and 4 weeks after treatment. Also, the 2-year outcome was compared.

RESULTS

There was a case of amputation in each group within 4 weeks after therapy. The pain scale significantly decreased in both groups [lcSSc 93 mm (s.d. 9) to 11 (s.d. 16), P < 0.01; ASO 77 mm (s.d. 22) to 16 (s.d. 13), P < 0.01] and TcPO2 significantly improved [lcSSc 9.0 mmHg (s.d. 9) to 35 (s.d. 14), P < 0.01; ASO 18 mmHg (s.d. 10) to 29 (s.d. 21), P < 0.05). At the 2-year follow-up, the limb amputation rate was 9.1% in lcSSc and 20.7% in ASO (P = 0.36), while the recurrence rate was 18.2% in lcSSc and 17.2% in ASO (P = 0.95). All-cause mortality was 27.3% in lcSSc and 17.2% in ASO (P = 0.65).

CONCLUSION

In patients with lcSSc, bone marrow mononuclear cell implantation provides clinical benefit and is safe, without major adverse reactions, and may become an effective strategy.

TRIAL REGISTRATION

UMIN-CTR, http://www.umin.ac.jp/ctr/index-j.htm, no. UMIN000004112.

A randomized, open-label, multicenter trial for the safety and efficacy of adult mesenchymal stem cells after acute myocardial infarction

Recent studies suggest that the intracoronary administration of bone marrow (BM)-derived mesenchymal stem cells (MSCs) may improve left ventricular function in patients with acute myocardial infarction (AMI). However, there is still argumentative for the safety and efficacy of MSCs in the AMI setting. We thus performed a randomized pilot study to investigate the safety and efficacy of MSCs in patients with AMI. Eighty patients with AMI after successful reperfusion therapy were randomly assigned and received an intracoronary administration of autologous BM-derived MSCs into the infarct related artery at 1 month. During follow-up period, 58 patients completed the trial. The primary endpoint was changes in left ventricular ejection fraction (LVEF) by single-photon emission computed tomography (SPECT) at 6 month. We also evaluated treatment-related adverse events. The absolute improvement in the LVEF by SPECT at 6 month was greater in the BM-derived MSCs group than in the control group (5.9% ± 8.5% vs 1.6% ± 7.0%; P=0.037). There was no treatment-related toxicity during intracoronary administration of MSCs. No significant adverse cardiovascular events occurred during follow-up. In conclusion, the intracoronary infusion of human BM-derived MSCs at 1 month is tolerable and safe with modest improvement in LVEF at 6-month follow-up by SPECT. (ClinicalTrials.gov registration number: NCT01392105).

Cell therapy for heart failure: a comprehensive overview of experimental and clinical studies, current challenges, and future directions

Despite significant therapeutic advances, the prognosis of patients with heart failure (HF) remains poor, and current therapeutic approaches are palliative in the sense that they do not address the underlying problem of the loss of cardiac tissue. Stem cell-based therapies have the potential to fundamentally transform the treatment of HF by achieving what would have been unthinkable only a few years ago-myocardial regeneration. For the first time since cardiac transplantation, a therapy is being developed to eliminate the underlying cause of HF, not just to achieve damage control. Since the initial report of cell therapy (skeletal myoblasts) in HF in 1998, research has proceeded at lightning speed, and numerous preclinical and clinical studies have been performed that support the ability of various stem cell populations to improve cardiac function and reduce infarct size in both ischemic and nonischemic cardiomyopathy. Nevertheless, we are still at the dawn of this therapeutic revolution. Many important issues (eg, mechanism(s) of action of stem cells, long-term engraftment, optimal cell type(s), and dose, route, and frequency of cell administration) remain to be resolved, and no cell therapy has been conclusively shown to be effective. The purpose of this article is to critically review the large body of work performed with respect to the use of stem/progenitor cells in HF, both at the experimental and clinical levels, and to discuss current controversies, unresolved issues, challenges, and future directions. The review focuses specifically on chronic HF; other settings (eg, acute myocardial infarction, refractory angina) are not discussed.

Role of stem-cell-derived microvesicles in the paracrine action of stem cells

The paracrine theory has recently changed the view of the biological action of stem cells and of the subsequent potential application of stem cells in regenerative medicine. Indeed, most of the beneficial effects of stem-cell-based therapy have been attributed to soluble factors released from stem cells. In this context, MVs (microvesicles) released as exosomes from the endosomal compartment, or as shedding vesicles from the cell surface, may play a relevant role in the intercellular communication between stem and injured cells. By transferring proteins, bioactive lipids, mRNA and microRNA, MVs act as vehicles of information that may lead to alteration of the phenotype of recipient cells. The exchange of information between stem cells and tissue-injured cells is reciprocal. The MV-mediated transfer of tissue-specific information from the injured cells to stem cells may reprogramme the latter to gain phenotypic and functional characteristics of the cell of origin. On the other hand, MVs released from stem cells may confer a stem-cell-like phenotype to injured cells, with the consequent activation of self-regenerative programmes. In fact, MVs released from stem cells retain several biological activities that are able to reproduce the beneficial effects of stem cells in a variety of experimental models.

Atorvastatin enhance efficacy of mesenchymal stem cells treatment for swine myocardial infarction via activation of nitric oxide synthase

BACKGROUND

In a swine model of acute myocardial infarction (AMI), Statins can enhance the therapeutic efficacy of mesenchymal stem cell (MSCs) transplantation. However, the mechanisms remain unclear. This study aims at assessing whether atorvastatin (Ator) facilitates the effects of MSCs through activation of nitric oxide synthase (NOS), especially endothelial nitric oxide synthase (eNOS), which is known to protect against ischemic injury.

METHODS AND RESULTS

42 miniswines were randomized into six groups (n = 7/group): Sham operation; AMI control; Ator only; MSC only, Ator+MSCs and Ator+MSCs+NG-nitrol-L-arginine (L-NNA), an inhibitor of NOS. In an open-heart surgery, swine coronary artery ligation and reperfusion model were established, and autologous bone-marrow MSCs were injected intramyocardium. Four weeks after transplantation, compared with the control group, Ator+MSCs animals exhibited decreased defect areas of both "perfusion" defined by Single-Photon Emission Computed Tomography (-6.2±1.8% vs. 2.0±5.1%, P = 0.0001) and "metabolism" defined by Positron Emission Tomography (-3.00±1.41% vs. 4.20±4.09%, P = 0.0004); Ejection fraction by Magnetic Resonance Imaging increased substantially (14.22±12.8% vs. 1.64±2.64%, P = 0.019). In addition, indices of inflammation, fibrosis, and apoptosis were reduced and survivals of MSCs or MSC-derived cells were increased in Ator+MSCs animals. In Ator or MSCs alone group, perfusion, metabolism, inflammation, fibrosis or apoptosis were reduced but there were no benefits in terms of heart function and cell survival. Furthermore, the above benefits of Ator+MSCs treatment could be partially blocked by L-NNA.

CONCLUSIONS

Atorvastatin facilitates survival of implanted MSCs, improves function and morphology of infarcted hearts, mediated by activation of eNOS and alleviated by NOS inhibitor. The data reveal the cellular and molecular mechanism for anti-AMI therapy with a combination of statin and stem cells.

Hypoxic conditioning enhances the angiogenic paracrine activity of human adipose-derived stem cells

Human adipose-derived stem cells (ASCs) secrete cytokines and growth factors that can be harnessed in a paracrine fashion for promotion of angiogenesis, cell survival, and activation of endogenous stem cells. We recently showed that hypoxia is a powerful stimulus for an angiogenic activity from ASCs in vitro and here we investigate the biological significance of this paracrine activity in an in vivo angiogenesis model. A single in vitro exposure of ASCs to severe hypoxia (<0.1% O2) significantly increased both the transcriptional and translational level of the vascular endothelial growth factor-A (VEGF-A) and angiogenin (ANG). The angiogenicity of the ASC-conditioned medium (ASC(CM)) was assessed by implanting ASC(CM)-treated polyvinyl alcohol sponges subcutaneously for 2 weeks in mice. The morphometric analysis of anti-CD31-immunolabeled sponge sections demonstrated an increased angiogenesis with hypoxic ASC(CM) treatment compared to normoxic control ASC(CM) treatment (percentage vascular volume; 6.0%±0.5% in the hypoxic ASC(CM) vs. 4.1%±0.7% in the normoxic ASC(CM), P<0.05). Reduction of VEGF-A and ANG levels in the ASC(CM) with respective neutralizing antibodies before sponge implantation showed a significantly diminished angiogenic response (3.5%±0.5% in anti-VEGF-A treated, 3.2%±0.7% in anti-ANG treated, and 3.5%±0.6% in anti-VEGF-A/ANG treated). Further, both the normoxic and hypoxic ASC(CM) were able to sustain in vivo lymphangiogenesis in sponges. Collectively, the model demonstrated that the increased paracrine production of the VEGF-A and ANG in hypoxic-conditioned ASCs in vitro translated to an in vivo effect with a favorable biological significance. These results further illustrate the potential for utilization of an in vitro optimized ASC(CM) for in vivo angiogenesis-related applications as an effective cell-free technology.

Mesenchymal stem cells ameliorate experimental peritoneal fibrosis by suppressing inflammation and inhibiting TGF-β1 signaling

Mesenchymal stem cells (MSCs) are multipotent adult stem cells that have regenerative capability and exert paracrine actions on damaged tissues. Since peritoneal fibrosis is a serious complication of peritoneal dialysis, we tested whether MSCs suppress this using a chlorhexidine gluconate model in rats. Although MSCs isolated from green fluorescent protein–positive rats were detected for only 3 days following their injection, immunohistochemical staining showed that MSCs suppressed the expression of mesenchymal cells, their effects on the deposition of extracellular matrix proteins, and the infiltration of macrophages for 14 days. Moreover, MSCs reduced the functional impairment of the peritoneal membrane. Cocultures of MSCs and human peritoneal mesothelial cells using a Transwell system indicated that the beneficial effects of MSCs on the glucose-induced upregulation of transforming growth factor-β1(TGF-β1) and fibronectin mRNA expression in the human cells were likely due to paracrine actions. Preincubation in MSC-conditioned medium suppressed TGF-β1-induced epithelial-to-mesenchymal transition, α-smooth muscle actin, and the decrease in zonula occludens-1 in cultured human peritoneal mesothelial cells. Although bone morphogenic protein 7 was not detected, MSCs secreted hepatocyte growth factor and a neutralizing antibody to this inhibited TGF-β1 signaling. Thus, our findings imply that MSCs ameliorate experimental peritoneal fibrosis by suppressing inflammation and TGF-β1 signaling in a paracrine manner.

Bone-marrow-derived mesenchymal stem cells for organ repair

Mesenchymal stem cells (MSCs) are prototypical adult stem cells with the capacity for self-renewal and differentiation with a broad tissue distribution. MSCs not only differentiate into types of cells of mesodermal lineage but also into endodermal and ectodermal lineages such as bone, fat, cartilage and cardiomyocytes, endothelial cells, lung epithelial cells, hepatocytes, neurons, and pancreatic islets. MSCs have been identified as an adherent, fibroblast-like population and can be isolated from different adult tissues, including bone marrow (BM), umbilical cord, skeletal muscle, and adipose tissue. MSCs secrete factors, including IL-6, M-CSF, IL-10, HGF, and PGE2, that promote tissue repair, stimulate proliferation and differentiation of endogenous tissue progenitors, and decrease inflammatory and immune reactions. In this paper, we focus on the role of BM-derived MSCs in organ repair.

Mesenchymal stem cells overexpressing integrin-linked kinase attenuate cardiac fibroblast proliferation and collagen synthesis through paracrine actions

Mesenchymal stem cells (MSCs) transfected by integrin-linked kinase (ILK) transplantation may improve the function and compliance of the post-infarct cardiac ventricle. We investigated the effect of ILK-modified MSC contiditioned medium (ILK-MSC-CM) on the proliferation of cardiac fibroblasts (CFBs) and collagen synthesis in vitro and in vivo. Myocardial infarction (MI)-induced animals received mesenchymal stem cell conditioned medium (MSC-CM), ILK-MSC-CM, or complete medium alone, subepicardially. A group of animals with MI and no other former intervention served as controls. ILK-MSC-CM inhibited CFB proliferation, reduced the gene expression of type I (Col1a1) and type III collagen (Col3a1), tissue inhibitors of metalloproteinase‑1 (TIMP-1) and ‑2 (TIMP-2), α smooth muscle actin (α-SMA), and connective tissue growth factor (CTGF). It also increased the gene expression of matrix metalloproteinase‑2 (MMP‑2) and -9 (MMP‑9), as measured by qRT-PCR. Four weeks after the left anterior descending (LAD) coronary artery ligation, echocardiographic analysis demonstrated preserved cardiac geometry and contractility in the ILK-MSC-CM treated animals. Decreased infarct size and reduced fibrosis were observed in the ILK-MSC-CM group. Overexpression of ILK regulates paracrine actions of MSCs, and ILK-MSC-CM attenuates CFB proliferation and collagen synthesis through paracrine actions in vitro and in vivo.

Bone marrow-derived mesenchymal stem cell attenuates skin fibrosis development in mice

Recent studies showed that mesenchymal stem cell (MSC) transplantation significantly alleviated tissue fibrosis; however, little is known about the efficacy on attenuating cutaneous scar formation. In this study, we established a dermal fibrosis model induced by bleomycin and evaluated the benefit of bone marrow-derived mesenchymal stem cells (BM-MSCs) on skin fibrosis development. Tracing assay of green fluorescent protein (GFP(+) )BM-MSCs showed that the cells disappeared gradually within 24 hours upon administration, which hinted the action of BM-MSCs in vivo was exerted in the initial phase of repair in this model. Therefore, we repeatedly transplanted syngeneic BM-MSCs in the process of skin fibrosis formation. After 3 weeks, it was found that BM-MSC-treated lesional skin demonstrated a unanimous basket-weave organisation of collagen arrangement similar to normal skin, with few inflammatory cells. In addition, lesional skin with BM-MSC treatment exhibited a significant down-regulation of transforming growth factor-β1 (TGF-β1), type I collagen and heat-shock protein 47 (HSP47), with higher expression of matrix metalloproteinases (MMPs)-2, -9 and -13. Further experiments showed that α-smooth muscle actin (α-SMA) positive cells, the most reliable marker of myofibroblasts, apparently decreased after BM-MSC transplantation, which revealed that BM-MSCs could attenuate myofibroblast proliferation and differentiation as well as matrix production. Taken together, these findings suggested that BM-MSCs can inhibit the formation process of bleomycin-induced skin fibrosis, alleviate inflammation and favour the remodelling of extracellular matrix.

Sustained therapeutic perfusion outside transplanted sites in chronic myocardial infarction after stem cell transplantation

This study aimed at comparing long-term variations in the perfusion of chronic myocardial infarction (MI) areas after local injections of autologous bone marrow stem cells (BMSCs). 14 coronary ligated rats with transmural chronic MI (4 months) were used: a control group (n = 7) versus a treated group (n = 7) in which (111)In labeled-BMSCs were directly engrafted on MI areas. By using (111)In/(99m)Tc SPECT and Sestamibi gated-SPECT,. left ventricle perfusion and function were monitored in all animals by serial (99m)Tc-Sestamibi pinhole gated-SPECT over a period of 6 months. Post-therapeutic myocardial perfusion improved as early as 48 h following injection in the 2 groups. This benefice was sustained during the 6-month follow-up in the non-engrafted MI-areas from treated rats (at 6-months: +10 ± 5 %), whereas the engrafted ones, as well as the MI areas from control rats, exhibited progressive deterioration over time (at 6-months: -9 ± 10 % and -5 ± 3 %, respectively). Perfusion enhancement of the chronic MI areas treated by BMSCs transplantation is: (1) marked in the following days, presumably because of an unspecific inflammatory reaction, and (2) sustained over the long term but only outside the sites of cell engraftment, suggesting a distant paracrine effect of transplanted cells.

Therapeutic potential of mesenchymal stem cell-derived microvesicles

Several studies have demonstrated that mesenchymal stem cells have the capacity to reverse acute and chronic kidney injury in different experimental models by paracrine mechanisms. This paracrine action may be accounted for, at least in part, by microvesicles (MVs) released from mesenchymal stem cells, resulting in a horizontal transfer of mRNA, microRNA and proteins. MVs, released as exosomes from the endosomal compartment, or as shedding vesicles from the cell surface, are now recognized as being an integral component of the intercellular microenvironment. By acting as vehicles for information transfer, MVs play a pivotal role in cell-to-cell communication. This exchange of information between the injured cells and stem cells has the potential to be bi-directional. Thus, MVs may either transfer transcripts from injured cells to stem cells, resulting in reprogramming of their phenotype to acquire specific features of the tissue, or conversely, transcripts could be transferred from stem cells to injured cells, restraining tissue injury and inducing cell cycle re-entry of resident cells, leading to tissue self-repair. Upon administration with a therapeutic regimen, MVs mimic the effect of mesenchymal stem cells in various experimental models by inhibiting apoptosis and stimulating cell proliferation. In this review, we discuss whether MVs released from mesenchymal stem cells have the potential to be exploited in novel therapeutic approaches in regenerative medicine to repair damaged tissues, as an alternative to stem cell-based therapy.

Stem cell transplantation as a therapy for cardiac fibrosis

Cardiac fibrosis is a fundamental constituent of most cardiac pathologies and represents the upshot of nearly all types of cardiac injury. Generally, fibrosis is a scarring process, characterized by accumulation of fibroblasts and deposition of increasing amounts of extracellular matrix (ECM) proteins in the myocardium. Therapeutic approaches that control fibroblast activity and evade maladaptive processes could represent a potential strategy to attenuate progression towards heart failure. Currently, cell therapy is actively perceived as an alternative to traditional pharmacological management of myocardial infarction (MI). The majority of the studies applying stem cell therapy following MI have demonstrated a decline in fibrosis. However, it was not clearly recognized whether the decline in cardiac fibrosis was due to replacement of dead cardiomyocytes or because of the direct effects of paracrine factors released from the transplanted stem cells on the ECM. Therefore, the main focus of this review is to discuss the impact of different types of stem cells on cardiac fibrosis and associated cardiac remodelling in a variety of experimental models of heart failure, particularly MI.

Exosomes for drug delivery - a novel application for the mesenchymal stem cell

Exosomes are the most extensively characterized class of secreted membrane vesicles that carry proteins and RNAs for intercellular communication. They are increasingly seen as possible alternatives to liposomes as drug delivery vehicles. Like liposomes, they could deliver their cargo across the plasma membrane and provide a barrier against premature transformation and elimination. In addition, these naturally-occurring secreted membrane vesicles are less toxic and better tolerated in the body as evidenced by their ubiquitous presence in biological fluids, and have an intrinsic homing ability. They are also amenable to in vivo and in vitro loading of therapeutic agents, and membrane modifications to enhance tissue-specific homing. Here we propose human mesenchymal stem cells as the ideal cell source of exosomes for drug delivery. Mesenchymal stem cell transplantation for various disease indications has been extensively tested and shown to be safe in numerous clinical trials. These cells are also prolific producers of immunologically inert exosomes. Immortalization of these cells does not compromise the quantity or quality of exosome production, thus enabling infinite and reproducible exosome production from a single cell clone.

Effect of human adipose derived stem cells on scar formation and remodeling in a pig model: a pilot study

BACKGROUND

Adipose-derived stem cells (ASCs) have positive effects in the wound healing process.

OBJECTIVE

To clarify whether ASCs positively mitigate scar formation in the wound remodeling process.

MATERIALS AND METHODS

Full-thickness skin defects were created on the dorsal skin of Yorkshire pigs. After the defects were transformed into early scars, ASCs were injected, and the same amount of phosphate buffered saline (PBS) was injected in the control group. Clinical and histologic examinations were performed.

RESULTS

In the experimental group, the areas of scars were smaller than those of control groups. The color of scars was more similar to that of the surrounding normal tissue, and scar pliability was better. The number of mast cells decreased, and more-mature collagen arrangement was noted. In the early period of scar remodeling, the expression of transforming growth factor beta (TGF-β)3 and matrix metalloproteinase 1 (MMP1) was greater in the experimental group than in control group. In the late period, the level of alpha smooth muscle actin and tissue inhibitor of metalloproteinase 1 were dramatically less, although the level of MMP1 was lower in the experimental group than in control group.

CONCLUSIONS

Local injection of ASCs decreases scar size and provides better color quality and scar pliability. It decreases the activity of mast cells and inhibits the action of TGF-β against fibroblasts and positively stimulates scar remodeling through greater expression of MMP molecules.

Mesenchymal stem cell therapy for attenuation of scar formation during wound healing

Scars are a consequence of cutaneous wound healing that can be both unsightly and detrimental to the function of the tissue. Scar tissue is generated by excessive deposition of extracellular matrix tissue by wound healing fibroblasts and myofibroblasts, and although it is inferior to the uninjured skin, it is able to restore integrity to the boundary between the body and its environment. Scarring is not a necessary process to repair the dermal tissues. Rather, scar tissue forms due to specific mechanisms that occur during the adult wound healing process and are modulated primarily by the inflammatory response at the site of injury. Adult tissue-derived mesenchymal stem cells, which participate in normal wound healing, are trophic mediators of tissue repair. These cells participate in attenuating inflammation in the wound and reprogramming the resident immune and wound healing cells to favor tissue regeneration and inhibit fibrotic tissue formation. As a result, these cells have been considered and tested as a likely candidate for a cellular therapy to promote scar-less wound healing. This review identifies specific mechanisms by which mesenchymal stem cells can limit tissue fibrosis and summarizes recent in vivo studies where these cells have been used successfully to limit scar formation.

Cell therapies for heart function recovery: focus on myocardial tissue engineering and nanotechnologies

Cell therapies have gained increasing interest and developed in several approaches related to the treatment of damaged myocardium. The results of multiple clinical trials have already been reported, almost exclusively involving the direct injection of stem cells. It has, however, been postulated that the efficiency of injected cells could possibly be hindered by the mechanical trauma due to the injection and their low survival in the hostile environment. It has indeed been demonstrated that cell mortality due to the injection approaches 90%. Major issues still need to be resolved and bed-to-bench followup is paramount to foster clinical implementations. The tissue engineering approach thus constitutes an attractive alternative since it provides the opportunity to deliver a large number of cells that are already organized in an extracellular matrix. Recent laboratory reports confirmed the interest of this approach and already encouraged a few groups to investigate it in clinical studies. We discuss current knowledge regarding engineered tissue for myocardial repair or replacement and in particular the recent implementation of nanotechnological approaches.

Intraperitoneal but not intravenous cryopreserved mesenchymal stromal cells home to the inflamed colon and ameliorate experimental colitis

Background and Aims

Mesenchymal stromal cells (MSCs) were shown to have immunomodulatory activity and have been applied for treating immune-mediated disorders. We compared the homing and therapeutic action of cryopreserved subcutaneous adipose tissue (AT-MSCs) and bone marrow-derived mesenchymal stromal cells (BM-MSCs) in rats with trinitrobenzene sulfonic acid (TNBS)–induced colitis.

Methods

After colonoscopic detection of inflammation AT-MSCs or BM-MSCs were injected intraperitoneally. Colonoscopic and histologic scores were obtained. Density of collagen fibres and apoptotic rates were evaluated. Cytokine levels were measured in supernatants of colon explants. For cell migration studies MSCs and skin fibroblasts were labelled with Tc-99m or CM-DiI and injected intraperitonealy or intravenously.

Results

Intraperitoneal injection of AT-MSCs or BM-MSCs reduced the endoscopic and histopathologic severity of colitis, the collagen deposition, and the epithelial apoptosis. Levels of TNF-α and interleukin-1β decreased, while VEGF and TGF-β did not change following cell-therapy. Scintigraphy showed that MSCs migrated towards the inflamed colon and the uptake increased from 0.5 to 24 h. Tc-99m-MSCs injected intravenously distributed into various organs, but not the colon. Cm-DiI-positive MSCs were detected throughout the colon wall 72 h after inoculation, predominantly in the submucosa and muscular layer of inflamed areas.

Conclusions

Intraperitoneally injected cryopreserved MSCs home to and engraft into the inflamed colon and ameliorate TNBS-colitis.

Comparative analysis of paracrine factor expression in human adult mesenchymal stem cells derived from bone marrow, adipose, and dermal tissue

Human adult mesenchymal stem cells (MSCs) support the engineering of functional tissue constructs by secreting angiogenic and cytoprotective factors, which act in a paracrine fashion to influence cell survival and vascularization. MSCs have been isolated from many different tissue sources, but little is known about how paracrine factor secretion varies between different MSC populations. We evaluated paracrine factor expression patterns in MSCs isolated from adipose tissue (ASCs), bone marrow (BMSCs), and dermal tissues [dermal sheath cells (DSCs) and dermal papilla cells (DPCs)]. Specifically, mRNA expression analysis identified insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor-D (VEGF-D), and interleukin-8 (IL-8) to be expressed at higher levels in ASCs compared with other MSC populations whereas VEGF-A, angiogenin, basic fibroblast growth factor (bFGF), and nerve growth factor (NGF) were expressed at comparable levels among the MSC populations examined. Analysis of conditioned media (CM) protein confirmed the comparable level of angiogenin and VEGF-A secretion in all MSC populations and showed that DSCs and DPCs produced significantly higher concentrations of leptin. Functional assays examining in vitro angiogenic paracrine activity showed that incubation of endothelial cells in ASC(CM) resulted in increased tubulogenic efficiency compared with that observed in DPC(CM). Using neutralizing antibodies we concluded that VEGF-A and VEGF-D were 2 of the major growth factors secreted by ASCs that supported endothelial tubulogenesis. The variation in paracrine factors of different MSC populations contributes to different levels of angiogenic activity and ASCs maybe preferred over other MSC populations for augmenting therapeutic approaches dependent upon angiogenesis.

Mesenchymal stem cells and cardiovascular disease: a bench to bedside roadmap

In recent years, the incredible boost in stem cell research has kindled the expectations of both patients and physicians. Mesenchymal progenitors, owing to their availability, ease of manipulation, and therapeutic potential, have become one of the most attractive options for the treatment of a wide range of diseases, from cartilage defects to cardiac disorders. Moreover, their immunomodulatory capacity has opened up their allogenic use, consequently broadening the possibilities for their application. In this review, we will focus on their use in the therapy of myocardial infarction, looking at their characteristics, in vitro and in vivo mechanisms of action, as well as clinical trials.

Dissecting paracrine effectors for mesenchymal stem cells

There has been increasing interest in the application of mesenchymal stem cells (MSCs) in regenerative medicine in recent years. In this context, the beneficial effects of MSCs have been ascribed mainly to a paracrine action rather than to direct replacement of the injured tissue. Indeed, MSCs produce a great variety of trophic and immunomodulatory factors. In this chapter, we provide an overview of growth factors and chemokines involved in stimulation of cell proliferation, inhibition of apoptosis, enhancement of angiogenesis, and suppression of inflammatory and immune response. In addition, we discuss the emerging role of the extracellular vesicles released from MSCs as possible paracrine mediators.

Role of GATA-4 in differentiation and survival of bone marrow mesenchymal stem cells

Cell and tissue regeneration is a relatively new research field and it incorporates a novel application of molecular genetics. Combinatorial approaches for stem-cell-based therapies wherein guided differentiation into cardiac lineage cells and cells secreting paracrine factors may be necessary to overcome the limitations and shortcomings of a singular approach. GATA-4, a GATA zinc-finger transcription factor family member, has been shown to regulate differentiation, growth, and survival of a wide range of cell types. In this chapter, we discuss whether overexpression of GATA-4 increases mesenchymal stem cell (MSC) transdifferentiation into cardiac phenotype and enhances the MSC secretome, thereby increasing cell survival and promoting postinfarction cardiac angiogenesis. MSCs engineered with GATA-4 enhance their capacity to differentiate into cardiac cell phenotypes, improve survival of the cardiac progenitor cells and their offspring, and modulate the paracrine activity of stem cells to support their angiomyogenic potential and cardioprotective effects.

Role of adrenomedullin in the growth and differentiation of stem and progenitor cells

Stem cells have captured the imagination of the general public by their potential as new therapeutic tools in the fight against degenerative diseases. This potential is based on their capability for self-renewal and at the same time for producing progenitor cells that will eventually provide the building blocks for tissue and organ regeneration. These processes are carefully orchestrated in the organism by means of a series of molecular cues. An emerging molecule which is responsible for some of these physiological responses is adrenomedullin, a 52-amino acid regulatory peptide which increases proliferation and regulates cell fate of stem cells of different origins. Adrenomedullin binds to specific membrane receptors in stem cells and induces several intracellular pathways such as those involving cAMP, Akt, or MAPK. Regulation of adrenomedullin levels may help in directing the growth and differentiation of stem cells for applications (e.g., cell therapy) both in vitro and in vivo.

Repair mechanisms of bone marrow mesenchymal stem cells in myocardial infarction

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite advances in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. Bone marrow-derived mesenchymal stem cells (MSCs) hold promise for cardiac repair following MI, due to their multilineage, self-renewal and proliferation potential. In addition, MSCs can be easily isolated, expanded in culture, and have immunoprivileged properties to the host tissue. Experimental studies and clinical trials have revealed that MSCs not only differentiate into cardiomyocytes and vascular cells, but also secrete amounts of growth factors and cytokines which may mediate endogenous regeneration via activation of resident cardiac stem cells and other stem cells, as well as induce neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility in a paracrine manner. It has also been postulated that the anti-arrhythmic and cardiac nerve sprouting potential of MSCs may contribute to their beneficial effects in cardiac repair. Most molecular and cellular mechanisms involved in the MSC-based therapy after MI are still unclear at present. This article reviews the potential repair mechanisms of MSCs in the setting of MI.