Reversal of endothelial progenitor cell dysfunction in patients with type 2 diabetes using a conditioned medium of human embryonic stem cell-derived endothelial cells

Endothelial progenitor cells as biomarkers of diabetes-related cardiovascular complications

Diabetes mellitus (DM) constitutes a chronic metabolic disease characterized by elevated levels of blood glucose which can also lead to the so-called diabetic vascular complications (DVCs), responsible for most of the morbidity, hospitalizations and death registered in these patients. Currently, different approaches to prevent or reduce DM and its DVCs have focused on reducing blood sugar levels, cholesterol management or even changes in lifestyle habits. However, even the strictest glycaemic control strategies are not always sufficient to prevent the development of DVCs, which reflects the need to identify reliable biomarkers capable of predicting further vascular complications in diabetic patients. Endothelial progenitor cells (EPCs), widely known for their potential applications in cell therapy due to their regenerative properties, may be used as differential markers in DVCs, considering that the number and functionality of these cells are affected under the pathological environments related to DM. Besides, drugs commonly used with DM patients may influence the level or behaviour of EPCs as a pleiotropic effect that could finally be decisive in the prognosis of the disease. In the current review, we have analysed the relationship between diabetes and DVCs, focusing on the potential use of EPCs as biomarkers of diabetes progression towards the development of major vascular complications. Moreover, the effects of different drugs on the number and function of EPCs have been also addressed.

Exploring Endothelial Colony-Forming Cells to Better Understand the Pathophysiology of Disease: An Updated Review

Endothelial cell (EC) dysfunction has been implicated in a variety of pathological conditions. The collection of ECs from patients is typically conducted postmortem or through invasive procedures, such as surgery and interventional procedures, hampering efforts to clarify the role of ECs in disease onset and progression. In contrast, endothelial colony-forming cells (ECFCs), also termed late endothelial progenitor cells, late outgrowth endothelial cells, blood outgrowth endothelial cells, or endothelial outgrowth cells, are obtained in a minimally invasive manner, namely, by the culture of human peripheral blood mononuclear cells in endothelial growth medium. ECFCs resemble mature ECs phenotypically, genetically, and functionally, making them excellent surrogates for ECs. Numerous studies have been performed that examined ECFC function in conditions such as coronary artery disease, diabetes mellitus, hereditary hemorrhagic telangiectasia, congenital bicuspid aortic valve disease, pulmonary arterial hypertension, venous thromboembolic disease, and von Willebrand disease. Here, we provide an updated review of studies using ECFCs that were performed to better understand the pathophysiology of disease. We also discuss the potential of ECFCs as disease biomarkers and the standardized methods to culture, quantify, and evaluate ECFCs and suggest the future direction of research in this field.

Endothelial Dysfunction in Pregnancy Complications

The endothelium, which constitutes the inner layer of blood vessels and lymphatic structures, plays an important role in various physiological functions. Alterations in structure, integrity and function of the endothelial layer during pregnancy have been associated with numerous gestational complications, including clinically significant disorders, such as preeclampsia, fetal growth restriction, and diabetes. While numerous experimental studies have focused on establishing the role of endothelial dysfunction in pathophysiology of these gestational complications, their mechanisms remain unknown. Numerous biomarkers of endothelial dysfunction have been proposed, together with the mechanisms by which they relate to individual gestational complications. However, more studies are required to determine clinically relevant markers specific to a gestational complication of interest, as currently most of them present a significant overlap. Although the independent diagnostic value of such markers remains to be insufficient for implementation in standard clinical practice at the moment, inclusion of certain markers in predictive multifactorial models can improve their prognostic value. The future of the research in this field lies in the fine tuning of the clinical markers to be used, as well as identifying possible therapeutic techniques to prevent or reverse endothelial damage.

Secretome of endothelial progenitor cells from stroke patients promotes endothelial barrier tightness and protects against hypoxia-induced vascular leakage

BACKGROUND

Cell-based therapeutic strategies have been proposed as an alternative for brain repair after stroke, but their clinical application has been hampered by potential adverse effects in the long term. The present study was designed to test the effect of the secretome of endothelial progenitor cells (EPCs) from stroke patients (scCM) on in vitro human models of angiogenesis and vascular barrier.

METHODS

Two different scCM batches were analysed by mass spectrometry and a proteome profiler. Human primary CD34+-derived endothelial cells (CD34+-ECs) were used for designing angiogenesis studies (proliferation, migration, and tubulogenesis) or in vitro models of EC monolayer (confluent monolayer ECs-CMECs) and blood-brain barrier (BBB; brain-like ECs-BLECs). Cells were treated with scCM (5 μg/mL) or protein-free endothelial basal medium (scEBM-control). CMECs or BLECs were exposed (6 h) to oxygen-glucose deprivation (OGD) conditions (1% oxygen and glucose-free medium) or normoxia (control-5% oxygen, 1 g/L of glucose) and treated with scCM or scEBM during reoxygenation (24 h).

RESULTS

The analysis of different scCM batches showed a good reproducibility in terms of protein yield and composition. scCM increased CD34+-EC proliferation, tubulogenesis, and migration compared to the control (scEBM). The proteomic analysis of scCM revealed the presence of growth factors and molecules modulating cell metabolism and inflammatory pathways. Further, scCM decreased the permeability of CMECs and upregulated the expression of the junctional proteins such as occludin, VE-cadherin, and ZO-1. Such effects were possibly mediated through the activation of the interferon pathway and a moderate downregulation of Wnt signalling. Furthermore, OGD increased the permeability of both CMECs and BLECs, while scCM prevented the OGD-induced vascular leakage in both models. These effects were possibly mediated through the upregulation of junctional proteins and the regulation of MAPK/VEGFR2 activity.

CONCLUSION

Our results suggest that scCM promotes angiogenesis and the maturation of newly formed vessels while restoring the BBB function in ischemic conditions. In conclusion, our results highlight the possibility of using EPC-secretome as a therapeutic alternative to promote brain angiogenesis and protect from ischemia-induced vascular leakage.

An In Vitro Comparison of Anti-Tumoral Potential of Wharton's Jelly and Bone Marrow Mesenchymal Stem Cells Exhibited by Cell Cycle Arrest in Glioma Cells (U87MG)

The therapeutic potential of mesenchymal stem cells (MSCs) for various malignancies is currently under investigation due to their unique properties. However, many discrepancies regarding their anti-tumoral or pro-tumoral properties have raised uncertainty about their application for anti-cancer therapies. To investigate, if the anti-tumoral or pro-tumoral properties are subjective to the type of MSCs under different experimental conditions we set out these experiments. Three treatments namely cell lysates (CL), serum-free conditioned media and FBS conditioned media (FBSCM) from each of Wharton’s Jelly MSCs and Bone Marrow-MSCs were applied to evaluate the anti-tumoral or pro-tumoral effect on the glioma cells (U87MG). The functional analysis included; Morphological evaluation, proliferation and migration potential, cell cycle analysis, and apoptosis for glioma cells. The fibroblast cell line was added to investigate the stimulatory or inhibitory effect of treatments on the proliferation of the normal cell. We found that cell lysates induced a generalized inhibitory effect on the proliferation of the glioma cells and the fibroblasts from both types of MSCs. Similarly, both types of conditioned media from two types of MSCs exerted the same inhibitory effect on the proliferation of the glioma cells. However, the effect of two types of conditioned media on the proliferation of fibroblasts was stimulatory from BM-MSCs and variable from WJ-MSCs. Moreover, all three treatments exerted a likewise inhibitory effect on the migration potential of the glioma cells. Furthermore, we found that the cell cycle was arrested significantly at the G1 phase after treating cells with conditioned media which may have led to inhibit the proliferative and migratory abilities of the glioma cells (U87MG). We conclude that cell extracts of MSCs in the form of secretome can induce specific anti-tumoral properties in serum-free conditions for the glioma cells particularly the WJ-MSCs and the effect is mediated by the cell cycle arrest at the G1 phase.

Stem Cell Transplant for Advanced Stage Liver Disorders: Current Scenario and Future Prospects

BACKGROUND

Chronic Liver Disorders (CLD), caused by the lifestyle patterns like alcoholism or by non-alcoholic fatty liver disease or because of virus-mediated hepatitis, affect a large population fraction across the world. CLD progresses into end-stage diseases with a high mortality rate. Liver transplant is the only approved treatment available for such end-stage disease patients. However, the number of liver transplants is limited due to the limited availability of suitable donors and the extremely high cost of performing the procedure. Under such circumstances, Stem Cell (SC) mediated liver regeneration has emerged as a potential therapeutic alternative approach.

OBJECTIVE

This review aims to critically analyze the current status and future prospects of stem cellbased interventions for end-stage liver diseases. The clinical studies undertaken, the mechanism underlying therapeutic effects and future directions have been examined.

METHOD

The clinical trial databases were searched at https://clinicaltrials.gov.in and http://www.isrctn.com to identify randomized, non-randomized and controlled studies undertaken with keywords such as "liver disorder and Mesenchymal Stem Cells (MSCs)", "liver cirrhosis and MSCs" and "liver disorder and SCs". Furthermore, https://www.ncbi.nlm.nih.gov/pubmed/ database was also explored with similar keywords for finding the available reports and their critical analyses.

RESULTS

The search results yielded a significant number of studies that used bone marrow-derived stem cells, MSCs and hepatocytes. The studies clearly indicated that SCs play a key role in the hepatoprotection process by some mechanisms involving anti-inflammation, auto-immune-suppression, angiogenesis and anti-apoptosis. Further, studies indicated that SCs derived paracrine factors promote angiogenesis, reduce inflammation and inhibit hepatocyte apoptosis.

CONCLUSION

The SC-based interventions provide a significant improvement in patients with CLD; however, there is a need for randomized, controlled studies with the analysis of a long-term follow-up.

The Functionality of Endothelial-Colony-Forming Cells from Patients with Diabetes Mellitus

Endothelial-colony-forming cells (ECFCs) are a population of progenitor cells which have demonstrated promising angiogenic potential both in vitro and in vivo. However, ECFCs from diabetic patients have been shown to be dysfunctional compared to ECFCs from healthy donors. Diabetes mellitus itself presents with many vascular co-morbidities and it has been hypothesized that ECFCs may be a potential cell therapy option to promote revascularisation in these disorders. While an allogeneic cell therapy approach would offer the potential of an ‘off the shelf’ therapeutic product, to date little research has been carried out on umbilical cord-ECFCs in diabetic models. Alternatively, autologous cell therapy using peripheral blood-ECFCs allows the development of a personalised therapeutic approach to medicine; however, autologous diabetic ECFCs are dysfunctional and need to be repaired so they can effectively treat diabetic co-morbidities. Many different groups have modified autologous diabetic ECFCs to improve their function using a variety of methods including pre-treatment with different factors or with genetic modification. While the in vitro and in vivo data from the literature is promising, no ECFC therapy has proceeded to clinical trials to date, indicating that more research is needed for a potential ECFC therapy in the future to treat diabetic complications.

Biological activity of mesenchymal stem cells secretome as a basis for cell-free therapeutic approach

Mesenchymal stem (stromal) cells (MSCs) are self-renewing, cultured adult stem cells which secrete a complex set of multiple soluble biologically active molecules such as chemokines, and cytokines, cell adhesion molecules, lipid mediators, interleukins (IL), growth factors (GFs), hormones, micro RNAs (miRNAs), long non-coding RNAs (lncRNAs), messenger RNAs (mRNAs), exosomes, as well as microvesicles, the secretome. MSCs of various origin, including adipose-derived stem cells (ASCs), bone marrow derived mesenchymal stem cells (BM-MSCs), human uterine cervical stem cells (hUCESCs), may be good candidates for obtaining secretome-derived products. Different population of MSCs can secret different factors which could have anti-inflammatory, anti-apoptotic, anti-fibrotic activities, a neuroprotective effect, could improve bone, muscle, liver regeneration and wound healing. Therefore, the paracrine activity of conditioned medium obtained when cultivating MSCs, due to a plethora of bioactive factors, was assumed to have the most prominent cell-free therapeutic impact and can serve as a better option in the field of regenerative medicine in future.

Mesenchymal stem cell-conditioned media: A novel alternative of stem cell therapy for quality wound healing

Mesenchymal stem cells-conditioned media (MSCs-CM) contains several growth factors and cytokines, thus may be used as a better alternative to stem cell therapy, which needs to be elucidated. The present study was conducted to evaluate the therapeutic potential of caprine, canine, and guinea pig bone marrow-derived MSCs-CM in excision wound healing in a guinea pig model. MSCs were obtained from bone marrow, expanded ex vivo and characterized as per ISCT criteria. CM was collected assayed by western blot to ascertain the presence of important secretory biomolecules. Quantitative estimation by enzyme-linked immunosorbent assay was done for a vascular epidermal growth factor (VEGF) and interleukin-6 (IL-6) in caprine MSCs-CM and optimum time for collection of CM was decided as 72 hr. CM from all the species was lyophilized by freeze-drying method. Full-thickness (2 × 2 cm² ) excision skin wounds were created in guinea pigs (six animals in each group) and respective lyophilized CM mixed with laminin gel was applied topically at weekly interval. On Day 28, histopathological examinations of healed skin were done by hemotoxylin and eosin staining. MSCs were found to secrete important growth factors and cytokines (i.e., VEGF, transforming growth factor-β1, fibroblast growth factor-2, insulin-like growth factor-1, stem cell factor, and IL-6) as demonstrated by immunohistochemistry and western blot assay. It was found that allogenic and xenogenic application of CM significantly improved quality wound healing with minimal scar formation. Thus, MSCs-CM can be used allogenically as well as xenogenically for quality wound healing.

Preserved endothelial progenitor cell angiogenic activity in African American essential hypertensive patients

Background

African American (AA) subjects with essential hypertension (EH) have greater inflammation and cardiovascular complications than Caucasian EH. An impaired endogenous cellular repair system may exacerbate vascular injury in hypertension, yet whether these differ between AA EH and Caucasian EH remains unknown. Vascular repair by circulating endothelial progenitor cells (EPCs) is controlled by regulators of EPC mobilization, homing, adhesion and new vessel formation, but can be hindered by various cytokines. We hypothesized that EPC levels and function would be impaired in AA EH compared with Caucasian EH, in association with increased levels of inflammatory mediators and EPC regulators.

Methods

CD34+/KDR+ EPCs were isolated from inferior vena cava and renal vein blood samples of AA EH and Caucasian EH patients (n = 18 each) and from peripheral veins of 17 healthy volunteers (HVs) and enumerated using fluorescence-activated cell sorting. Angiogenic function of late-outgrowth endothelial cells expanded from these samples for 3 weeks was tested in vitro. Levels of inflammatory mediators, angiogenic factors and EPC regulators were measured by Luminex.

Results

EPC levels were decreased in both AA and Caucasian EH compared with HVs, whereas their late-outgrowth endothelial cell angiogenic function was comparable. Levels of several inflammatory mediators were elevated in AA EH compared with Caucasian EH and HVs. Contrarily, vascular endothelial growth factor and its receptor-2 were lower. EPC levels inversely correlated with blood pressure in all hypertensive patients and estimated glomerular filtration rate with inflammatory mediators only in AA EH.

Conclusions

Despite lower EPC numbers, decreased vascular endothelial growth factor signaling and inflammation, EPC function is preserved in AA EH compared with Caucasian EH and HVs, suggesting compensatory mechanisms for vascular repair.

Engineering mesenchymal stem cells to improve their exosome efficacy and yield for cell-free therapy

Through traditional medicine, there were diseases and disorders that previously remained untreated or were simply thought to be incurable. Since the discovery of mesenchymal stem cells (MSCs), there has been a flurry of research to develop MSC-based therapy for diseases and disorders. It is now well-known that MSCs do not typically engraft after transplantation and exhibit their therapeutic effect via a paracrine mechanism. In addition to secretory proteins, MSCs also produce extracellular vesicles (EVs), membrane-bound nanovesicles containing proteins, DNA and RNA. The secreted vesicles then interact with target cells and deliver their contents, imparting their ultimate therapeutic effect. Unlike the widely studied cancer cells, the yield of MSC-exosomes is a limiting factor for large-scale production for cell-free therapies. Here we summarise potential approaches to increase the yield of such vesicles while maintaining or enhancing their efficacy by engineering the extracellular environment and intracellular components of MSCs.

Conditioned Medium Protects Dopaminergic Neurons in Parkinsonian Rats

Objective

Adipose derived stem cells (ASCs) secrete numerous neurotrophic factors and cytokines in conditioned medium (CM), which protect neurons by its antioxidative and trophic effects. This research assesses the neuroprotective effect of ASC- CM on neurotrophins genes expressions and tyrosine hydroxylase positive (TH+) cell density in male Wistar rats lesioned by 6-hydroxydopamine (6-OHDA).

Materials and Methods

In this experimental study, the groups consisted of lesioned and sham rats with unilateral injections of 20 µg of 6-OHDA neurotoxin and phosphate buffered saline (PBS) into the striatum, respectively. Another groups received intravenous injections of 3×10⁶ cells (ASCs group), 500 µl of CM (ASC-CM group) or medium [α-minimal essential medium (α-MEM) group)]. All rats underwent evaluations with the rotarod and apomorphine-induced rotation tests at 2, 4, 6, and 8 weeks post-injection. At 8 weeks we sacrificed some of the animals for real-time polymerase chain reaction (PCR) analysis, and evaluation of TH+cell counts.

Results

We observed a significant decrease in contralateral turns to the lesions in the ASCs and ASC-CM groups compared to the neurotoxin lesioned or α-MEM groups at 8 weeks post transplantation. Cell and CM- injected rats showed a significant increase of staying on the rotarod compared to the lesion or α-MEM groups. Cell and CM-treated rats showed significant increases in the NGF and NT3 genes, respectively, compared with the lesion group. Both treated groups showed significant increases in BDNF gene expression and TH⁺ cell density.

Conclusion

The results suggested that ASCs and ASC-CM protected dopaminergic neurons through the expressions of neurotrophin genes.

Mesenchymal Stem Cell Secretome: Toward Cell-Free Therapeutic Strategies in Regenerative Medicine

Earlier research primarily attributed the effects of mesenchymal stem cell (MSC) therapies to their capacity for local engrafting and differentiating into multiple tissue types. However, recent studies have revealed that implanted cells do not survive for long, and that the benefits of MSC therapy could be due to the vast array of bioactive factors they produce, which play an important role in the regulation of key biologic processes. Secretome derivatives, such as conditioned media or exosomes, may present considerable advantages over cells for manufacturing, storage, handling, product shelf life and their potential as a ready-to-go biologic product. Nevertheless, regulatory requirements for manufacturing and quality control will be necessary to establish the safety and efficacy profile of these products. Among MSCs, human uterine cervical stem cells (hUCESCs) may be a good candidate for obtaining secretome-derived products. hUCESCs are obtained by Pap cervical smear, which is a less invasive and painful method than those used for obtaining other MSCs (for example, from bone marrow or adipose tissue). Moreover, due to easy isolation and a high proliferative rate, it is possible to obtain large amounts of hUCESCs or secretome-derived products for research and clinical use.

Modeling Treatment Response for Lamin A/C Related Dilated Cardiomyopathy in Human Induced Pluripotent Stem Cells

BACKGROUND

Precision medicine is an emerging approach to disease treatment and prevention that takes into account individual variability in the environment, lifestyle, and genetic makeup of patients. Patient-specific human induced pluripotent stem cells hold promise to transform precision medicine into real-life clinical practice. Lamin A/C (LMNA)-related cardiomyopathy is the most common inherited cardiomyopathy in which a substantial proportion of mutations in the LMNA gene are of nonsense mutation. PTC124 induces translational read-through over the premature stop codon and restores production of the full-length proteins from the affected genes. In this study we generated human induced pluripotent stem cells-derived cardiomyocytes from patients who harbored different LMNA mutations (nonsense and frameshift) to evaluate the potential therapeutic effects of PTC124 in LMNA-related cardiomyopathy.

METHODS AND RESULTS

We generated human induced pluripotent stem cells lines from 3 patients who carried distinctive mutations (R225X, Q354X, and T518fs) in the LMNA gene. The cardiomyocytes derived from these human induced pluripotent stem cells lines reproduced the pathophysiological hallmarks of LMNA-related cardiomyopathy. Interestingly, PTC124 treatment increased the production of full-length LMNA proteins in only the R225X mutant, not in other mutations. Functional evaluation experiments on the R225X mutant further demonstrated that PTC124 treatment not only reduced nuclear blebbing and electrical stress-induced apoptosis but also improved the excitation-contraction coupling of the affected cardiomyocytes.

CONCLUSIONS

Using cardiomyocytes derived from human induced pluripotent stem cells carrying different LMNA mutations, we demonstrated that the effect of PTC124 is codon selective. A premature stop codon UGA appeared to be most responsive to PTC124 treatment.

Exploring pericyte and cardiac stem cell secretome unveils new tactics for drug discovery

Ischaemic diseases remain a major cause of morbidity and mortality despite continuous advancements in medical and interventional treatments. Moreover, available drugs reduce symptoms associated with tissue ischaemia, without providing a definitive repair. Cardiovascular regenerative medicine is an expanding field of research that aims to improve the treatment of ischaemic disorders through restorative methods, such as gene therapy, stem cell therapy, and tissue engineering. Stem cell transplantation has salutary effects through direct and indirect actions, the latter being attributable to growth factors and cytokines released by stem cells and influencing the endogenous mechanisms of repair. Autologous stem cell therapies offer less scope for intellectual property coverage and have limited scalability. On the other hand, off-the-shelf cell products and derivatives from the stem cell secretome have a greater potential for large-scale distribution, thus enticing commercial investors and reciprocally producing more significant medical and social benefits. This review focuses on the paracrine properties of cardiac stem cells and pericytes, two stem cell populations that are increasingly attracting the attention of regenerative medicine operators. It is likely that new cardiovascular drugs are introduced in the next future by applying different approaches based on the refinement of the stem cell secretome.

The structural and functional recovery of pancreatic β-cells in type 1 diabetes mellitus induced mesenchymal stem cell-conditioned medium

AIM

Various studies have shown that secreted factors alone in culture medium without stem cell are capable of repairing tissues by itself in various conditions involving damaged tissue/organ. Therefore, this study was aimed to investigate the role of human umbilical cord mesenchymal stem cell-derived conditioned medium (CM) on the recovery of pancreatic β-cells in Wistar rats (Rattus norvegicus) with type 1 diabetes mellitus.

MATERIALS AND METHODS

The 0.05 ml CM induction was applied to the diabetic group of rats in weeks 1, 2, 3, and 4. 1 week after each CM induction, insulin concentration was analyzed using ELISA. The pancreas was divided into 3 regions, processed by paraffin method, stained with hematoxylin-eosin, and immunohistochemical method for insulin.

RESULTS

This study indicated the decrease in the total number of islets and insulin concentration after the injection of single dose of alloxan. The exocrine acini were also damaged. Microscopic observation detected the presence of small islets in the diabetic group 1 week after the first 0.05 ml CM induction. The number and size of the islets increased in line with the CM doses and time of inductions. Immunohistochemically, the presence of low intensity of insulin-positive cells could be recognized at the splenic and duodenal regions of the pancreas, but not gastric region, 1 week after the first and second 0.05 ml CM induction. The intensity of staining and the number of insulin-positive cells increased dramatically in 1 week after the third and fourth 0.05 ml of CM induction in all regions of the pancreas. The data of insulin blood concentration showed clear differences between the second and the fourth induction of 0.05 ml CM induction.

CONCLUSIONS

This study showed very strong evidence on the role of human umbilical cord mesenchymal stem cell-derived CM in recovering the pancreatic β-cells damage in Wistar rats (R. norvegicus) with type 1 diabetes mellitus, structurally and functionally.

Neovascularization Potential of Blood Outgrowth Endothelial Cells From Patients With Stable Ischemic Heart Failure Is Preserved

Background

Blood outgrowth endothelial cells (BOECs) mediate therapeutic neovascularization in experimental models, but outgrowth characteristics and functionality of BOECs from patients with ischemic cardiomyopathy (ICMP) are unknown. We compared outgrowth efficiency and in vitro and in vivo functionality of BOECs derived from ICMP with BOECs from age‐matched (ACON) and healthy young (CON) controls.

Methods and Results

We isolated 3.6±0.6 BOEC colonies/100×10⁶ mononuclear cells (MNCs) from 60‐mL blood samples of ICMP patients (n=45; age: 66±1 years; LVEF: 31±2%) versus 3.5±0.9 colonies/100×10⁶MNCs in ACON (n=32; age: 60±1 years) and 2.6±0.4 colonies/100×10⁶MNCs in CON (n=55; age: 34±1 years), P=0.29. Endothelial lineage (VEGFR2⁺/CD31⁺/CD146⁺) and progenitor (CD34⁺/CD133⁻) marker expression was comparable in ICMP and CON. Growth kinetics were similar between groups (P=0.38) and not affected by left ventricular systolic dysfunction, maladaptive remodeling, or presence of cardiovascular risk factors in ICMP patients. In vitro neovascularization potential, assessed by network remodeling on Matrigel and three‐dimensional spheroid sprouting, did not differ in ICMP from (A)CON. Secretome analysis showed a marked proangiogenic profile, with highest release of angiopoietin‐2 (1.4±0.3×10⁵ pg/10⁶ICMP‐BOECs) and placental growth factor (5.8±1.5×10³ pg/10⁶ICMP BOECs), independent of age or ischemic disease. Senescence‐associated β‐galactosidase staining showed comparable senescence in BOECs from ICMP (5.8±2.1%; n=17), ACON (3.9±1.1%; n=7), and CON (9.0±2.8%; n=13), P=0.19. High‐resolution microcomputed tomography analysis in the ischemic hindlimb of nude mice confirmed increased arteriogenesis in the thigh region after intramuscular injections of BOECs from ICMP (P=0.025; n=8) and CON (P=0.048; n=5) over vehicle control (n=8), both to a similar extent (P=0.831).

Conclusions

BOECs can be successfully culture‐expanded from patients with ICMP. In contrast to impaired functionality of ICMP‐derived bone marrow MNCs, BOECs retain a robust proangiogenic profile, both in vitro and in vivo, with therapeutic potential for targeting ischemic disease.

Adipose-derived stem cells from diabetic mice show impaired vascular stabilization in a murine model of diabetic retinopathy

Diabetic retinopathy is characterized by progressive vascular dropout with subsequent vision loss. We have recently shown that an intravitreal injection of adipose-derived stem cells (ASCs) can stabilize the retinal microvasculature, enabling repair and regeneration of damaged capillary beds in vivo. Because an understanding of ASC status from healthy versus diseased donors will be important as autologous cellular therapies are developed for unmet clinical needs, we took advantage of the hyperglycemic Akimba mouse as a preclinical in vivo model of diabetic retinopathy in an effort aimed at evaluating therapeutic efficacy of adipose-derived stem cells (mASCs) derived either from healthy, nondiabetic or from diabetic mice. To these ends, Akimba mice received intravitreal injections of media conditioned by mASCs or mASCs themselves, subsequent to development of substantial retinal capillary dropout. mASCs from healthy mice were more effective than diabetic mASCs in protecting the diabetic retina from further vascular dropout. Engrafted ASCs were found to preferentially associate with the retinal vasculature. Conditioned medium was unable to recapitulate the vasoprotection seen with injected ASCs. In vitro diabetic ASCs showed decreased proliferation and increased apoptosis compared with healthy mASCs. Diabetic ASCs also secreted less vasoprotective factors than healthy mASCs, as determined by high-throughput enzyme-linked immunosorbent assay. Our findings suggest that diabetic ASCs are functionally impaired compared with healthy ASCs and support the utility of an allogeneic injection of ASCs versus autologous or conditioned media approaches in the treatment of diabetic retinopathy.

Prospect of stem cell conditioned medium in regenerative medicine

BACKGROUND

Stem cell-derived conditioned medium has a promising prospect to be produced as pharmaceuticals for regenerative medicine.

OBJECTIVE

To investigate various methods to obtain stem cell-derived conditioned medium (CM) to get an insight into their prospect of application in various diseases.

METHODS

Systematic review using keywords "stem cell" and "conditioned medium" or "secretome" and "therapy." Data concerning treated conditions/diseases, type of cell that was cultured, medium and supplements to culture the cells, culture condition, CM processing, growth factors and other secretions that were analyzed, method of application, and outcome were noted, grouped, tabulated, and analyzed.

RESULTS

Most of CM using studies showed good results. However, the various CM, even when they were derived from the same kind of cells, were produced by different condition, that is, from different passage, culture medium, and culture condition. The growth factor yields of the various types of cells were available in some studies, and the cell number that was needed to produce CM for one application could be computed.

CONCLUSION

Various stem cell-derived conditioned media were tested on various diseases and mostly showed good results. However, standardized methods of production and validations of their use need to be conducted.

The dipeptidyl peptidase-4 inhibitor saxagliptin improves function of circulating pro-angiogenic cells from type 2 diabetic patients

BACKGROUND

Type 2 diabetes (T2D) is associated with reduction and dysfunction of circulating pro-angiogenic cells (PACs). DPP-4 inhibitors, a class of oral agents for T2D, might possess pleiotropic vasculoprotective activities. Herein, we tested whether DPP-4 inhibition with Saxagliptin affects the function of circulating PACs from T2D and healthy subjects.

METHODS

PACs were isolated from T2D (n = 20) and healthy (n = 20) subjects. Gene expression, clonogenesis, proliferation, adhesion, migration and tubulisation were assessed in vitro by incubating PACs with or without Saxagliptin and SDF-1α. Stimulation of angiogenesis by circulating cells from T2D patients treated with Saxagliptin or other non-incretinergic drugs was assessed in vivo using animal models.

RESULTS

Soluble DPP-4 activity was predominant over cellular activity and was successfully inhibited by Saxagliptin. At baseline, T2D compared to healthy PACs contained less acLDL(+)Lectin(+) cells, and showed altered expression of genes related to adhesion and cell cycle regulation. This was reflected by impaired adhesion and clonogenesis/proliferative response of T2D PACs. Saxagliptin + SDF-1α improved adhesion and tube sustaining capacity of PACs from T2D patients. CD14+ PACs were more responsive to Saxagliptin than CD14- PACs. While Saxagliptin modestly reduced angiogenesis by mature endothelial cells, circulating PACs-progeny cells from T2D patients on Saxagliptin treatment displayed higher growth factor-inducible in vivo angiogenetic activity, compared to cells from T2D patients on non-incretinergic regimen.

CONCLUSIONS

Saxagliptin reverses PACs dysfunction associated with T2D in vitro and improves inducible angiogenesis by circulating cells in vivo. These data add knowledge to the potential pleiotropic cardiovascular effects of DPP-4 inhibition.

Specific role of impaired glucose metabolism and diabetes mellitus in endothelial progenitor cell characteristics and function

The disease burden of diabetes mellitus (DM) and its associated cardiovascular complications represent a growing and major global health problem. Recent studies suggest that circulating exogenous endothelial progenitor cells (EPCs) play an important role in endothelial repair and neovascularization at sites of injury or ischemia. Both experimental and clinical studies have demonstrated that hyperglycemia related to DM can induce alterations to EPCs. The reduction and dysfunction of EPCs related to DM correlate with the occurrence and severity of microvascular and macrovascular complications, suggesting a close mechanistic link between EPC dysfunction and impaired vascular function/repair in DM. These alterations to EPCs, likely mediated by multiple pathophysiological mechanisms, including inflammation, oxidative stress, and alterations in Akt and the nitric oxide pathway, affect EPCs at multiple stages: differentiation and mobilization in the bone marrow, trafficking and survival in the circulation, and homing and neovascularization. Several different therapeutic approaches have consequently been proposed to reverse the reduction and dysfunction of EPCs in DM and may represent a novel therapeutic approach to prevent and treat DM-related cardiovascular complications.

An upregulation in the expression of vanilloid transient potential channels 2 enhances hypotonicity-induced cytosolic Ca²⁺ rise in human induced pluripotent stem cell model of Hutchinson-Gillford Progeria

Hutchinson-Gillford Progeria Syndrome (HGPS) is a fatal genetic disorder characterized by premature aging in multiple organs including the skin, musculoskeletal and cardiovascular systems. It is believed that an increased mechanosensitivity of HGPS cells is a causative factor for vascular cell death and vascular diseases in HGPS patients. However, the exact mechanism is unknown. Transient receptor potential (TRP) channels are cationic channels that can act as cellular sensors for mechanical stimuli. The aim of this present study was to examine the expression and functional role of TRP channels in human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from the patients with HGPS. The mRNA and protein expression of TRP channels in HGPS and control (IMR90) iPSC-ECs were examined by semi-quantitative RT-PCRs and immunoblots, respectively. Hypotonicity-induced cytosolic Ca²⁺ ([Ca²⁺]_i) rise in iPSC-ECs was measured by confocal microscopy. RT-PCRs and immunoblots showed higher expressional levels of TRPV2 in iPSC-ECs from HGPS patients than those from normal individuals. In functional studies, hypotonicity induced a transient [Ca²⁺]_i rise in iPSC-ECs from normal individuals but a sustained [Ca²⁺]_i elevation in iPSC-ECs from HGPS patients. A nonselective TRPV inhibitor, ruthenium red (RuR, 20 µM), and a specific TRPV2 channel inhibitor, tranilast (100 µM), abolished the sustained phase of hypotonicity-induced [Ca²⁺]_i rise in iPSC-ECs from HGPS patients, and also markedly attenuated the transient phase of the [Ca²⁺]_i rise in these cells. Importantly, a short 10 min hypotonicity treatment caused a substantial increase in caspase 8 activity in iPSC-ECs from HGPS patients but not in cells from normal individuals. Tranilast could also inhibit the hypotonicity-induced increase in caspase 8 activity. Taken together, our data suggest that an up-regulation in TRPV2 expression causes a sustained [Ca²⁺]_i elevation in HGPS-iPSC-ECs under hypotonicity, consequently resulting in apoptotic cell death. This mechanism may contribute to the pathogenesis of vascular diseases in HGPS patients.