Adipose-derived cell construct stabilizes heart function and increases microvascular perfusion in an established infarct

Therapeutic application of adipose-derived stromal vascular fraction in myocardial infarction

The insufficiency of natural regeneration processes in higher organisms, including humans, underlies myocardial infarction (MI), which is one of the main causes of disability and mortality in the population of developed countries. The solution to this problem lies in the field of revealing the mechanisms of regeneration and creating on this basis new technologies for stimulating endogenous regenerative processes or replacing lost parts of tissues and organs with transplanted cells. Of great interest is the use of the so-called stromal vascular fraction (SVF), derived from autologous adipose tissue. It is known that the main functions of SVF are angiogenetic, antiapoptotic, antifibrotic, immune regulation, anti-inflammatory, and trophic. This study presents data on the possibility of using SVF, targeted regulation of its properties and reparative potential, as well as the results of research studies on its use for the restoration of damaged ischemic tissue after MI.

An Ex Vivo Tissue Culture Method for Discovering Cell Dynamics Involved in Stromal Vascular Fraction Vasculogenesis Using the Mouse Mesentery

Stromal vascular fraction (SVF), isolated from adipose tissue, identifies as a rich cell source comprised of endothelial cells, endothelial progenitor cells, pericytes, smooth muscle cells, fibroblasts, and immune cells. SVF represents a promising therapeutic heterogonous cell source for growing new blood microvessels due to its rich niche of cells. However, the spatiotemporal dynamics of SVF within living tissues remain largely unknown. The objective of this chapter is to describe a protocol for culturing SVF on mouse mesentery tissues in order to aid in the discovery of SVF dynamics and associated vessel growth over time. SVF was isolated from the inguinal adipose from adult mice and seeded onto mesentery tissues. Tissues were then cultured for up to 5 days and labeled with endothelial cell and pericyte markers. Representative results demonstrate the observation of SVF-derived vasculogenesis characterized by de novo vessel formation and subsequent vessel connection.

Will stem cells from fat and growth factors from blood bring new hope to female patients with reproductive disorders?

Female reproductive system disorders (FRSD) with or without infertility are prevalent women's health problems with a variety of treatment approaches including surgery and hormone therapy. It currently considering to sub-branch of regenerative medicine including stem cells or growth factors injection-based delivery treatment might be improved female reproductive health life. The most common products used for these patients treatment are autologous cell or platelet-based products from patients, including platelet-rich plasma, plasma rich in growth factor, platelet-rich fibrin, and stromal vascular fraction. In this review, we discuss each of the above products used in treatment of FRSD and critically evaluate the clinical outcome.

3D Bioprinting the Cardiac Purkinje System Using Human Adipogenic Mesenchymal Stem Cell Derived Purkinje Cells

PURPOSE

The objective of this study was to reprogram human adipogenic mesenchymal stem cells (hADMSCs) to form Purkinje cells and to use the reprogrammed Purkinje cells to bioprint Purkinje networks.

METHODS

hADMSCs were reprogrammed to form Purkinje cells using a multi-step process using transcription factors ETS2 and MESP1 to first form cardiac progenitor stem cells followed by SHOX2 and TBX3 to form Purkinje cells. A novel bioprinting method was developed based on Pluronic acid as the sacrificial material and type I collagen as the structural material. The reprogrammed Purkinje cells were used in conjunction with the novel bioprinting method to bioprint Purkinje networks. Printed constructs were evaluated for retention of functional protein connexin 40 (Cx40) and ability to undergo membrane potential changes in response to physiologic stimulus.

RESULTS

hADMSCs were successfully reprogrammed to form Purkinje cells based on the expression pattern of IRX3, IRX5, SEMA and SCN10. Reprogrammed purkinje cells were incorporated into a collagen type-1 bioink and the left ventricular Purkinje network was printed using anatomical images of the bovine Purkinje system as reference. Optimization studies demonstrated that 1.8 mg/mL type-I collagen at a seeding density of 300,000 cells per 200 µL resulted in the most functional bioprinted Purkinje networks. Furthermore, bioprinted Purkinje networks formed continuous syncytium, retained expression of vital functional gap junction protein Cx40 post-print, and exhibited membrane potential changes in response to electric stimulation and acetylcholine evaluated by DiBAC₄(5), an electrically responsive dye.

CONCLUSION

Based on the results of this study, hADMSCs were successfully reprogrammed to form Purkinje cells and bioprinted to form Purkinje networks.

3D bioprinting and its potential impact on cardiac failure treatment: An industry perspective

3D printing technologies are emerging as a disruptive innovation for the treatment of patients in cardiac failure. The ability to create custom devices, at the point of care, will affect both the diagnosis and treatment of cardiac diseases. The introduction of bioinks containing cells and biomaterials and the development of new computer assisted design and computer assisted manufacturing systems have ushered in a new technology known as 3D bioprinting. Small scale 3D bioprinting has successfully created cardiac tissue microphysiological systems. 3D bioprinting provides an opportunity to evaluate the assembly of specific parts of the heart and most notably heart valves. With the continuous development of instrumentation and bioinks and a complete understanding of cardiac tissue development, it is proposed that 3D bioprinting may permit the assembly of a heart described as a total biofabricated heart.

Intratunical Injection of Human Adipose Tissue-Derived Stem Cells Restores Collagen III/I Ratio in a Rat Model of Chronic Peyronie's Disease

INTRODUCTION

Previous studies have shown that the injection of adipose tissue-derived stem cells (ADSCs) into the tunica albuginea (TA) during the active phase of Peyronie's disease (PD) prevents the development of fibrosis.

AIM

To investigate, using an animal model, whether local injection of human ADSCs (hADSCs) can alter the degree of fibrosis in the chronic phase of PD.

METHODS

27 male, 12-week-old rats were divided into 3 equal groups: sham, PD without treatment, and PD treated with hADSCs 1 month after disease induction. Sham rats underwent 2 injections of vehicle into the TA 1 month apart. PD rats underwent transforming growth factor β1 (TGFβ1) injection and injection of vehicle 1 month later. PD-hADSC rats underwent TGFβ1 injection followed by 1 million hADSCs 1 month later. 1 week after treatment, n = 3 animals/group were euthanized, and the penises were harvested for quantitative polymerase chain reaction. 1 month after treatment, the other animals, n = 6 per group, underwent measurement of intracavernous pressure (ICP) and mean arterial pressure (MAP) during electrostimulation of the cavernous nerve. After euthanasia, penises were again harvested for histology and Western blot.

MAIN OUTCOME MEASURE

The primary outcome measures included (a) gene expression at one week post-injection; (b) measurement of ICP/MAP upon cavernous nerve stimulation as a measure of erectile function; (c) elastin, collagen I and III protein expression; and (d) Histomorphometric analysis of the penis. Means where compared by analysis of variance (ANOVA) followed by a Student-Newman-Keuls test for post hoc comparisons or Mann-Whitney test when applicable.

RESULTS

No significant difference was noted in ICP or ICP/MAP in response to cavernous nerve electrostimulation between the 3 groups at 2.5, 5, and 7.5 V (P > .05 for all voltages). PD animals developed tunical and subtunical areas of fibrosis with a significant upregulation of collagen III protein. The collagen III/I ratio was higher in the PD (4.6 ± 0.92) group compared with sham (0.66 ± 0.18) and PD-hADSC (0.86 ± 0.06) groups (P < .05) These fibrotic changes were prevented when treated with hADSCs. Compared with PD rats, PD-hADSC rats demonstrated a decreased expression of several fibrosis-related genes.

CONCLUSION

Injection of hADSCs reduces collagen III expression in a rat model of chronic PD. Castiglione F, Hedlund P, Weyne E, et al. Intratunical Injection of Human Adipose Tissue-Derived Stem Cells Restores Collagen III/I Ratio in a Rat Model of Chronic Peyronie's Disease. Sex Med 2019;7:94-103.

Paracrine potential of adipose stromal vascular fraction cells to recover hypoxia-induced loss of cardiomyocyte function

Cell-based therapies show promising results in cardiac function recovery mostly through paracrine-mediated processes (as angiogenesis) in chronic ischemia. In this study, we aim to develop a 2D (two-dimensional) in vitro cardiac hypoxia model mimicking severe cardiac ischemia to specifically investigate the prosurvival paracrine effects of adipose tissue-derived stromal vascular fraction (SVF) cell secretome released upon three-dimensional (3D) culture. For the 2D-cardiac hypoxia model, neonatal rat cardiomyocytes (CM) were cultured for 5 days at < 1% (approaching anoxia) oxygen (O₂ ) tension. Typical cardiac differentiation hallmarks and contractile ability were used to assess both the cardiomyocyte loss of functionality upon anoxia exposure and its possible recovery following the 5-day-treatment with SVF-conditioned media (collected following 6-day-perfusion-based culture on collagen scaffolds in either normoxia or approaching anoxia). The culture at < 1% O ₂ for 5 days mimicked the reversible condition of hibernating myocardium with still living and poorly contractile CM (reversible state). Only SVF-medium conditioned in normoxia expressing a high level of the prosurvival hepatocyte-growth factor (HGF) and insulin-like growth factor (IGF) allowed the partial recovery of the functionality of damaged CM. The secretome generated by SVF-engineered tissues showed a high paracrine potential to rescue the nonfunctional CM, therefore resulting in a promising patch-based treatment of specific low-perfused areas after myocardial infarction.

Adipose-derived cells improve left ventricular diastolic function and increase microvascular perfusion in advanced age

An early manifestation of coronary artery disease in advanced age is the development of microvascular dysfunction leading to deficits in diastolic function. Our lab has previously shown that epicardial treatment with adipose-derived stromal vascular fraction (SVF) preserves microvascular function following coronary ischemia in a young rodent model. Follow-up studies showed intravenous (i.v.) delivery of SVF allows the cells to migrate to the walls of small vessels and reset vasomotor tone. Therefore we tested the hypothesis that the i.v. cell injection of SVF would reverse the coronary microvascular dysfunction associated with aging in a rodent model. Fischer 344 rats were divided into 4 groups: young control (YC), old control (OC), old + rat aortic endothelial cells (O+EC) and old + GFP+ SVF cells (O+SVF). After four weeks, cardiac function and coronary flow reserve (CFR) were measured via echocardiography, and hearts were explanted either for histology or isolation of coronary arterioles for vessel reactivity studies. In a subgroup of animals, microspheres were injected during resting and dobutamine-stimulated conditions to measure coronary blood flow. GFP+ SVF cells engrafted and persisted in the myocardium and coronary vasculature four weeks following i.v. injection. Echocardiography showed age-related diastolic dysfunction without accompanying systolic dysfunction; diastolic function was improved in old rats after SVF treatment. Ultrasound and microsphere data both showed increased stimulated coronary blood flow in O+SVF rats compared to OC and O+EC, while isolated vessel reactivity was mostly unchanged. I.v.-injected SVF cells were capable of incorporating into the vasculature of the aging heart and are shown in this study to improve CFR and diastolic function in a model of advanced age. Importantly, SVF injection did not lead to arrhythmias or increased mortality in aged rats. SVF cells provide an autologous cell therapy option for treatment of microvascular and cardiac dysfunction in aged populations.

Vasculogenic and angiogenic potential of adipose stromal vascular fraction cell populations in vitro

Adipose-derived stromal vascular fraction (SVF) is a heterogeneous cell source that contains endothelial cells, pericytes, smooth muscle cells, stem cells, and other accessory immune and stromal cells. The SVF cell population has been shown to support vasculogenesis in vitro as well vascular maturation in vivo. Matrigel, an extracellular matrix (ECM) mixture has been utilized in vitro to evaluate tube formation of purified endothelial cell systems. We have developed an in vitro system that utilizes freshly isolated SVF and ECM molecules both in pure form (fibrin, laminin, collagen) as well as premixed form (Matrigel) to evaluate endothelial tip cell formation, endothelial stalk elongation, and early stages of branching and inosculation. Freshly isolated SVF rat demonstrate cell aggregation and clustering (presumptive vasculogenesis) on Matrigel ECM within the first 36 h of seeding followed by tip cell formation, stalk cell formation, branching, and inosculation (presumptive angiogenesis) during the subsequent 4 days of culture. Purified ECM molecules (laminin, fibrin, and collagen) promote cell proliferation but do not recapitulate events seen on Matrigel. We have created an in vitro system that provides a functional assay to study the mechanisms of vasculogenesis and angiogenesis in freshly isolated SVF to characterize SVF’s blood vessel forming potential prior to clinical implantation.

Comparison of Stromal Vascular Fraction with or Without a Novel Bioscaffold to Fibrin Glue in a Porcine Model of Mechanically Induced Anorectal Fistula

BACKGROUND

Anorectal fistulas (ARFs) are a common, devastating, event in the life of a patient with Crohn's disease. ARFs occur in up to 50% of patients with Crohn's disease. Treatment begins with surgical drainage of the initial abscess, followed by antibiotic therapy, then anti-inflammatory medications. If medical therapy fails to close the fistula tract, surgical intervention is often pursued. Surgery incurs risk of incontinence because of sphincter injury. Increasingly, the role of cell-based therapy is being investigated in ARFs. We evaluated the role a bioabsorbable scaffold plays in delivering cell-based therapy using a porcine model of AFR.

METHODS

ARFs were mechanically created and matured by setons. After 28 days, setons were removed; periaortic fat was harvested and processed for stromal vascular fraction (SVF). The cells were labeled with a membrane stain for later identification, then injected into the fistula or implanted through scaffold. Fistulas not treated with cells were injected with fibrin glue. Animals were monitored visually for healing at weeks 2 and 4, then euthanized to evaluate fistulas for histologic healing.

RESULTS

All fistulas (6/6) treated with SVF + scaffolds healed by week 2, compared with only 4/6 with just SVF and 0/5 treated with fibrin glue. Scaffolds retained SVF within the fistula tract more readily than injection method and SVF+scaffold treatment accelerated the healing process. Robust neovascularization was also seen in fistulas treated with SVF+scaffold. No adverse events occurred.

CONCLUSIONS

Scaffold technology may improve cell-based therapy healing rates for Crohn's ARFs. This advance should be investigated by human trials.

Effects of donor age on human adipose-derived adherent stromal cells under oxidative stress conditions

Objective

Adipose-derived stromal vascular fractions (SVFs) are heterogeneous complex populations of cells with therapeutic efficacy for tissue generation and vascular stabilization. SVFs have cardiomyogenic potential, and many researchers have examined the possibility of SVF transplantation for heart disease. In cell-based therapies, donor age affects the regenerative capability, cell yield, and differentiation potential of adult tissues; however, opposing or controversial results have been found in humans. We examined whether SVF transplantation into impaired heart tissue shows differential effects according to donor age.

Methods

We investigated differences in protein expression in human umbilical vein endothelial cells (HUVECs) co-cultured with adipose-derived adherent stromal cells (ADASs) from donors of different ages [>40-year-olds (40s group) and >60-year-olds (60s group)] under oxidative stress conditions.

Results

Although co-culturing HUVECs with ADASs ameliorated inflammation due to increased oxidative stress conditions, few differences were observed between the ADASs from the 40s and 60s groups. Moreover, the Database for Annotation, Visualization, and Integrated Discovery classification tool revealed differentially expressed genes in the Kyoto Encyclopedia of Genes and Genomes pathway associated with cytokine–cytokine receptor interaction in response to ADASs.

Conclusion

Protein expression profiles were unchanged in HUVECs induced by isolated ADASs from donors of different ages under oxidative stress conditions.

Use of adipose tissue and stromal vascular fraction in hand surgery

Adipose tissue is an abundant source of various cell types including not only adipocytes, but also progenitor and endothelial cells from thestroma. Interest in adipose tissue has surged since the identification in 2001 of adipose-derived stem cells (ADSCs) and of the stromal vascular fraction (SVF) obtained from adipose tissue by enzymatic digestion and centrifugation. SVF has been proven effective in ensuring tissue regeneration, thus improving tissue trophicityand vascularisation. These effects have generated strong interest among both physicians and surgeons, particularly in the field of hand surgery. Several applications have been developed and used, for instance to treat Dupuytren's contracture, systemic sclerosis-related hand lesions, and skin ageing at the hand. Other uses are being evaluated in clinical or animal studies. The objective of this article is to review the capabilities of adipose tissue and their current and potential applications in hand surgery.

Gender-dimorphic effects of adipose-derived stromal vascular fractions on HUVECs exposed to oxidative stress

Stromal vascular fractions (SVFs) are a heterogeneous collection of cells within adipose tissue that are being studied for various clinical indications. In this study, we aimed to determine whether SVF transplantation into impaired tissues has differential effects on inflammatory and angiogenetic properties with regard to gender. As reactive oxygen species have been implicated in cardiovascular disease development, we investigated differences in gene and protein expression related to inflammation and angiogenesis in HUVECs co-cultured with adipose-derived SVFs from male (M group) and female (F group) individuals under oxidative stress conditions. The expression of several inflammatory (interleukin (IL)-33) and angiogenetic (platelet-derived growth factor (PDGF)) factors differed dramatically between male and female donors. Anti-inflammatory and pro-angiogenetic responses were observed in HUVECs co-cultured with SVFs under oxidative stress conditions, and these characteristics may exhibit partially differential effects according to gender. Using network analysis, we showed that co-culturing HUVECs with SVFs ameliorated pyroptosis/apoptosis via an increase in oxidative stress. Activation of caspase-1 and IL-1B was significantly altered in HUVECs co-cultured with SVFs from female donors. These findings regarding gender-dimorphic regulation of adipose-derived SVFs provide valuable information that can be used for evidence-based gender-specific clinical treatment of SVF transplantation for understanding of cardiovascular disease, allowing for the development of additional treatment.

Delivery of mesenchymal stem cells in biomimetic engineered scaffolds promotes healing of diabetic ulcers

AIM

We hypothesized that delivery of mesenchymal stem cells (MSCs) in a biomimetic collagen scaffold improves wound healing in a diabetic mouse model.

MATERIALS & METHODS

Rolled collagen scaffolds containing MSCs were implanted or applied topically to diabetic C57BL/6 mice with excisional wounds.

RESULTS

Rolled scaffolds were hypoxic, inducing MSC synthesis and secretion of VEGF. Diabetic mice with wounds treated with rolled scaffolds containing MSCs showed increased healing compared with controls. Histologic examination showed increased cellular proliferation, increased VEGF expression and capillary density, and increased numbers of macrophages, fibroblasts and smooth muscle cells. Addition of laminin to the collagen scaffold enhanced these effects.

CONCLUSION

Activated MSCs delivered in a biomimetic-collagen scaffold enhanced wound healing in a translationally relevant diabetic mouse model.

Adipose-Derived Stromal Vascular Fraction Cell Effects on a Rodent Model of Thin Endometrium

Endometrial dysfunction affects approximately 1% of infertile women, and there is currently no standard therapy for improving fertility treatment outcomes in these patients. In our study, we utilized a rodent model of thin endometrium to test whether intrauterine application of adipose-derived stromal vascular fraction cells (SVF) could improve morphological and physiological markers of endometrial receptivity. Using anhydrous ethanol, endometrial area and gland density were significantly reduced in our model of thin endometrium. Application of SVF was associated with a 29% reduction in endometrial vascular endothelial growth factor (VEGF) expression and significant increases in uterine artery systolic/diastolic velocity ratios and resistance index values, suggesting reduced diastolic microvascular tone. However, no significant improvements in endometrial area or gland density were observed following SVF treatment. 3D confocal imaging demonstrated poor engraftment of SVF cells into recipient tissue, which likely contributed to the negative results of this study. We suspect modified treatment protocols utilizing adjuvant estrogen and/or tail vein cell delivery may improve SVF retention and therapeutic response in subsequent studies. SVF is an easily-obtainable cell product with regenerative capability that may have a future role in the treatment of infertile women with endometrial dysfunction.

Imaging the Stromal Vascular Fraction during Soft-Tissue Reconstruction

BACKGROUND

Although fat grafting is an increasingly popular practice, suboptimal volume retention remains an obstacle. Graft enrichment with the stromal vascular fraction has gained attention as a method of increasing graft retention. However, few studies have assessed the fate and impact of transplanted stromal vascular fraction on fat grafts. In vivo imaging techniques can be used to help determine the influence stromal vascular fraction has on transplanted fat.

METHODS

Stromal vascular fraction was labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR), a near-infrared dye, and tracked in vivo. Proliferation and differentiation of labeled cells were assessed to confirm that labeling did not adversely affect cellular function. Different doses of labeled stromal vascular fraction were tracked within fat grafts over time using the in vivo imaging system.

RESULTS

No significant differences in differentiation and proliferation were observed in labeled versus unlabeled cells (p > 0.05). A pilot study confirmed that stromal vascular fraction fluorescence was localized to fat grafts and different cell doses could be distinguished. A larger-scale in vivo study revealed that stromal vascular fraction fluorescence was statistically significant (p < 0.05) between different cell dose groups and this significance was maintained in higher doses (3 × 10(6) and 2 × 10(6) cells/ml of fat graft) for up to 41 days in vivo.

CONCLUSIONS

DiR labeling allowed the authors to differentiate between cell doses and confirm localization. This article supports the use of DiR labeling in conjunction with in vivo imaging as a tool for imaging stromal vascular fraction within fat grafts.

Human adipose-derived stromal cells for the production of completely autologous self-assembled tissue-engineered vascular substitutes

There is a clinical need for small-diameter vascular substitutes, notably for coronary and peripheral artery bypass procedures since these surgeries are limited by the availability of grafting material. This study reports the characterization of a novel autologous tissue-engineered vascular substitute (TEVS) produced in 10weeks exclusively from human adipose-derived stromal cells (ASC) self-assembly, and its comparison to an established model made from dermal fibroblasts (DF). Briefly, ASC and DF were cultured with ascorbate to form cell sheets subsequently rolled around a mandrel. These TEVS were further cultured as a maturation period before undergoing mechanical testing, histological analyses and endothelialization. No significant differences were measured in burst pressure, suture strength, failure load, elastic modulus and failure strain according to the cell type used to produce the TEVS. Indeed, ASC- and DF-TEVS both displayed burst pressures well above maximal physiological blood pressure. However, ASC-TEVS were 1.40-fold more compliant than DF-TEVS. The structural matrix, comprising collagens type I and III, fibronectin and elastin, was very similar in all TEVS although histological analysis showed a wavier and less dense collagen matrix in ASC-TEVS. This difference in collagen organization could explain their higher compliance. Finally, human umbilical vein endothelial cells (HUVEC) successfully formed a confluent endothelium on ASC and DF cell sheets, as well as inside ASC-TEVS. Our results demonstrated that ASC are an alternative cell source for the production of TEVS displaying good mechanical properties and appropriate endothelialization.

Stromal vascular stem cell treatment decreases muscle fibrosis following chronic rotator cuff tear

PURPOSE

Rotator cuff injuries are associated with atrophy and fat infiltration into the muscle, commonly referred to as "fatty degeneration." As the poor function of chronically torn muscles may limit recovery after surgical repair, there is considerable interest in finding therapies to enhance muscle regeneration. Stromal vascular fraction stem cells (SVFCs) can improve muscle regeneration in other chronic injury states, and our objective was to evaluate the ability of SVFCs to reduce fibrosis and fat accumulation, and enhance muscle fibre specific force production after chronic rotator cuff tear.

METHODS

Chronic supraspinatus tears were induced in adult immunodeficient rats, and repaired one month following tear. Rats received vehicle control, or injections of 3 × 10(5) or 3 × 10(6) human SVFCs into supraspinatus muscles.

RESULTS

Two weeks following repair, we detected donor human DNA and protein in SVFC treated muscles. There was a 40 % reduction in fibrosis in the treated groups compared to controls (p = 0.03 for 3 × 10(5), p = 0.04 for 3 × 10(6)), and no differences between groups for lipid content or force production were observed.

CONCLUSIONS

As there has been much interest in the use of stem cell-based therapies in musculoskeletal regenerative medicine, the reduction in fibrosis and trend towards an improvement in single fiber contractility suggest that SVFCs may be beneficial to enhance the treatment and recovery of patients with chronic rotator cuff tears.

Systemically delivered adipose stromal vascular fraction cells disseminate to peripheral artery walls and reduce vasomotor tone through a CD11b+ cell-dependent mechanism

Vasoactivity, an important aspect of tissue healing, is often compromised in disease and tissue injury. Dysfunction in the smaller vasoactive arteries is most impactful, given the role of these vessels in controlling downstream tissue perfusion. The adipose stromal vascular fraction (SVF) is a mix of homeostatic cells shown to promote tissue healing. Our objective was to test the hypothesis that autologous SVF cells therapeutically modulate peripheral artery vasoactivity in syngeneic mouse models of small artery function. Analysis of vasoactivity of saphenous arteries isolated from normal mice 1 week after intravenous injection of freshly isolated SVF cells revealed that pressure-dependent artery vasomotor tone was decreased by the SVF cell isolate, but not one depleted of CD11b(+) cells. Scavenging hydrogen peroxide in the vessel wall abrogated the artery relaxation promoted by the SVF cell isolate. Consistent with a CD11b(+) cell being the relevant cell type, SVF-derived F4/80-positive macrophages were present within the adventitia of the artery wall coincident with vasorelaxation. In a model of artery inflammation mimicking a common disease condition inducing vasoactive dysfunction, the SVF cells potentiated relaxation of saphenous arteries without structurally remodeling the artery via a CD11b(+) cell-dependent manner. Our findings demonstrate that freshly isolated, adipose SVF cells promote vasomotor relaxation in vasoactive arteries via a hydrogen peroxide-dependent mechanism that required CD11b(+) cells (most likely macrophages). Given the significant impact of small artery dysfunction in disease, we predict that the intravenous delivery of this therapeutic cell preparation would significantly improve tissue perfusion, particularly in diseases with diffuse vascular involvement.

Adipose-derived stem cells from both visceral and subcutaneous fat deposits significantly improve contractile function of infarcted rat hearts

Adipose-derived stem cells (ASCs) from subcutaneous and visceral adipose tissues have been studied individually. No studies have compared their abilities in treatment of heart failure. This study was designed to evaluate whether ASCs from the two sources could provide a long-term improvement of cardiac function in infarcted hearts. Rat subcutaneous and visceral adipose tissues were excised for isolation of ASCs. Morphology, yield, proliferation, surface markers, differentiation, and cytokine secretion of the subcutaneous ASCs (S-ASCs) and visceral ASCs (V-ASCs) were analyzed. Then a rat model of myocardial infarction (MI) was established by a coronary occlusion. Seven days after occlusion, S-ASCs (n = 22), V-ASCs (n = 22), and Dulbecco's modified Eagle medium (DMEM, n = 20) were injected into the infarct rim, respectively. Cardiac function was then monitored with MRI for up to 6 months. The hearts were then removed for histological assessments. The yield of V-ASCs per gram of the visceral adipose depot was significantly greater than that of S-ASCs in 1 g of the subcutaneous adipose depot. On the other hand, the S-ASCs showed a greater proliferation rate and colony-forming unit relative to the V-ASCs. In addition, the infarcted hearts treated with either S-ASCs or V-ASCs showed a significantly greater left ventricular ejection fraction (LVEF) than those treated with DMEM at 4 weeks and 6 months following the cell/DMEM transplantation. Moreover, the infarct sizes of both S-ASC- and V-ASC-treated hearts were significantly smaller than that in the DMEM-treated hearts. MRI showed the implanted ASCs at the end of 6 months of recovery. Despite the differences in cell yield, proliferation, and colony formation capacity, both S-ASCs and V-ASCs provide a long-lasting improvement of cardiac contractile function in infarcted hearts. We conclude that the subcutaneous and visceral adipose tissues are equally effective cell sources for cell therapy of heart failure.

Stem cell mechanisms during left ventricular remodeling post-myocardial infarction: Repair and regeneration

Post-myocardial infarction (MI), the left ventricle (LV) undergoes a series of events collectively referred to as remodeling. As a result, damaged myocardium is replaced with fibrotic tissue consequently leading to contractile dysfunction and ultimately heart failure. LV remodeling post-MI includes inflammatory, fibrotic, and neovascularization responses that involve regulated cell recruitment and function. Stem cells (SCs) have been transplanted post-MI for treatment of LV remodeling and shown to improve LV function by reduction in scar tissue formation in humans and animal models of MI. The promising results obtained from the application of SCs post-MI have sparked a massive effort to identify the optimal SC for regeneration of cardiomyocytes and the paradigm for clinical applications. Although SC transplantations are generally associated with new tissue formation, SCs also secrete cytokines, chemokines and growth factors that robustly regulate cell behavior in a paracrine fashion during the remodeling process. In this review, the different types of SCs used for cardiomyogenesis, markers of differentiation, paracrine factor secretion, and strategies for cell recruitment and delivery are addressed.