Evaluation of mobilized peripheral blood CD34(+) cells from patients with severe coronary artery disease as a source of endothelial progenitor cells

FACTORS INFLUENCING POST- CRYOPRESERVED CD34+ CELLS VIABILITY IN THE HARVESTED PRODUCTS OF AUTOLOGOUS HAEMATOPOIETIC STEM CELLS

The cryopreservation process of stem cells potentially cause the loss of CD34+ cells. The aim of this study is to evaluate association of patient, graft and technical characteristics with post cryopreserved CD34+ cells viability among lymphoproliferative disease namely multiple myeloma (MM) and lymphoma patients at Hospital Universiti Sains Malaysia (USM). This retrospective study was conducted in the Transplant Unit. A search of the hospital data (2008-2018) to identify 132 patients for both MM and lymphoma who underwent autologous peripheral blood haematopoietic stem cells (APBSC) mobilisation, and were successfully harvested and cryopreserved. Selected patients' profile as well as selected parameters of stem cell mobilization and cryopreservation were obtained from laboratory information system (LIS), record unit and the Transplant Unit. Multiple logistic regression (MLR) was used to find significant associated factors and p <0.05 was considered significant. The mean age of the patients was 39 years old with almost equal gender distribution and majority were lymphoma patients, 96 (72.7%) while 36 (27.3%) were multiple myeloma (MM) patients. The significant influencing factors of post-cryopreserved CD34+ cells viability were pre-cryopreserved CD34+ cell viability, total nucleated cells (TNC), and anti-platelet and antibiotics usage. Patients who are not on anti-platelet and have higher pre-cryopreserved CD34+ cells viability have higher chance for good post-cryopreserved CD34+ cells viability. While, those patients with higher TNC and on antibiotics have lower chance for good post cryopreserved CD34+ cells viability. This study showed patients who are not on anti-platelet and antibiotics will have higher probability of achieving good post cryopreserved CD34+ cells viability. The APBSC products with higher pre-cryopreserved CD34+ cells viability and lower TNC will achieve better post-cryopreserved CD34+ cells viability. The addition of extra plasma to the APBSC products is recommended to reduce the TNC.

Collagen biomaterial stimulates the production of extracellular vesicles containing microRNA-21 and enhances the proangiogenic function of CD34+ cells

CD34⁺ cells are promising for revascularization therapy, but their clinical use is limited by low cell counts, poor engraftment, and reduced function after transplantation. In this study, a collagen type I biomaterial was used to expand and enhance the function of human peripheral blood CD34⁺ cells, and potential underlying mechanisms were examined. Compared to the fibronectin control substrate, biomaterial-cultured CD34⁺ cells from healthy donors had enhanced proliferation, migration toward VEGF, angiogenic potential, and increased secretion of CD63⁺CD81⁺ extracellular vesicles (EVs). In the biomaterial-derived EVs, greater levels of the angiogenic microRNAs (miRs), miR-21 and -210, were detected. Notably, biomaterial-cultured CD34⁺ cells had reduced mRNA and protein levels of Sprouty (Spry)1, which is an miR-21 target and negative regulator of endothelial cell proliferation and angiogenesis. Similar to the results of healthy donor cells, biomaterial culture increased miR-21 and -210 expression in CD34⁺ cells from patients who underwent coronary artery bypass surgery, which also exhibited improved VEGF-mediated migration and angiogenic capacity. Therefore, collagen biomaterial culture may be useful for expanding the number and enhancing the function of CD34⁺ cells in patients, possibly mediated through suppression of Spry1 activity by EV-derived miR-21. These results may provide a strategy to enhance the therapeutic potency of CD34⁺ cells for vascular regeneration.-McNeill, B., Ostojic, A., Rayner, K. J., Ruel, M., Suuronen, E. J. Collagen biomaterial stimulates the production of extracellular vesicles containing microRNA-21 and enhances the proangiogenic function of CD34⁺ cells.

Difference in Serum Endostatin Levels in Diabetic Patients with Critical Limb Ischemia Treated by Autologous Cell Therapy or Percutaneous Transluminal Angioplasty

The aim of this study was to compare the serum levels of the anti-angiogenic factor endostatin (S-endostatin) as a potential marker of vasculogenesis after autologous cell therapy (ACT) versus percutaneous transluminal angioplasty (PTA) in diabetic patients with critical limb ischemia (CLI). A total of 25 diabetic patients with CLI treated in our foot clinic during the period 2008–2014 with ACT generating potential vasculogenesis were consecutively included in the study; 14 diabetic patients with CLI who underwent PTA during the same period were included in a control group in which no vasculogenesis had occurred. S-endostatin was measured before revascularization and at 1, 3, and 6 months after the procedure. The effect of ACT and PTA on tissue ischemia was confirmed by transcutaneous oxygen pressure (TcPO₂) measurement at the same intervals. While S-endostatin levels increased significantly at 1 and 3 months after ACT (both P < 0.001), no significant change of S-endostatin after PTA was observed. Elevation of S-endostatin levels significantly correlated with an increase in TcPO₂ at 1 month after ACT (r = 0.557; P < 0.001). Our study showed that endostatin might be a potential marker of vasculogenesis because of its significant increase after ACT in diabetic patients with CLI in contrast to those undergoing PTA. This increase may be a sign of a protective feedback mechanism of this anti-angiogenic factor.

Fertility rescue and ovarian follicle growth promotion by bone marrow stem cell infusion

OBJECTIVE

To assess if infusion of human bone marrow-derived stem cells (BMDSCs) could promote follicle development in patients with impaired ovarian functions.

DESIGN

Experimental design.

SETTING

University research laboratories.

ANIMAL(S)

Immunodeficient NOD/SCID female mice.

INTERVENTION(S)

Human BMDSCs were injected into mice with chemotherapy-induced ovarian damage and into immunodeficient mice xenografted with human cortex from poor-responder patients (PRs).

MAIN OUTCOME MEASURE(S)

Follicle development, ovulation, and offspring. Apoptosis, proliferation, and vascularization were evaluated in mouse and human ovarian stroma.

RESULT(S)

Fertility rescue and spontaneous pregnancies were achieved in mice ovaries mimicking PRs and ovarian insufficiency, induced by chemotherapy, after BMDSC infusion. Furthermore, BMDSC treatment resulted in production of higher numbers of preovulatory follicles, metaphase II oocytes, 2-cell embryos, and healthy pups. Stem cells promoted ovarian vascularization and cell proliferation, along with reduced apoptosis. In xenografted human ovarian tissues from PRs, infusion of BMDSCs and their CD133+ fraction led to their engraftment close to follicles, resulting in promotion of follicular growth, increases in E₂ secretion, and enhanced local vascularization.

CONCLUSION(S)

Our results raised the possibility that promoting ovarian angiogenesis by BMDSC infusion could be an alternative approach to improve follicular development in women with impaired ovarian function.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02240342.

Mesenchymal Stem Cell Administration in Patients with Chronic Obstructive Pulmonary Disease: State of the Science

Patients with chronic obstructive pulmonary disease (COPD) have chronic, irreversible airway inflammation; currently, there is no effective or curative treatment and the main goals of COPD management are to mitigate symptoms and improve patients' quality of life. Stem cell based therapy offers a promising therapeutic approach that has shown potential in diverse degenerative lung diseases. Preclinical studies have demonstrated encouraging outcomes of mesenchymal stem/stromal cells (MSCs) therapy for lung disorders including emphysema, bronchopulmonary dysplasia, fibrosis, and acute respiratory distress syndrome. This review summarizes available data on 15 studies currently registered by the ClinicalTrials.gov repository, which used different stem cell therapy protocols for COPD; these included bone marrow mononuclear cells (BMMCs), bone marrow-derived MSCs, adipose-derived stem/stromal cells (ADSCs), and adipose-derived MSCs. Published results of three trials indicate that administering BMMCs or MSCs in the setting of degenerative lung disease is safe and may improve patients' condition and quality of life; however, larger-scale studies are needed to evaluate efficacy. Results of another completed trial (NCT01872624) are not yet published, and eleven other studies are ongoing; these include MSCs therapy in emphysema, several studies of ADSCs in COPD, another in idiopathic pulmonary fibrosis, and plerixafor mobilization of CD117 stem cells to peripheral blood.

VEGFR2-Targeted Contrast-Enhanced Ultrasound to Distinguish between Two Anti-Angiogenic Treatments

The aim of this study was to evaluate the capacity of BR55, an ultrasound contrast agent specifically targeting vascular endothelial growth factor receptor 2 (VEGFR2), to distinguish the specific anti-VEGFR2 therapy effect of sunitinib from other anti-angiogenic effects of a therapy (imatinib) that does not directly inhibit VEGFR2. Sunitinib, imatinib and placebo were administered daily for 11 d (264 h) to 45 BalbC mice bearing ectopic CT26 murine colorectal carcinomas. During the course of therapy, B-mode ultrasound, contrast-enhanced ultrasound and VEGFR2-targeted contrast-enhanced ultrasound were performed to assess tumor morphology, vascularization and VEGFR2 expression, respectively. The angiogenic effects on these three aspects were characterized using tumor volume, contrast-enhanced area and differential targeted enhancement. Necrosis, microvasculature and expression of VEGFR2 were also determined by histology and immunostaining. B-Mode imaging revealed that tumor growth was significantly decreased in sunitinib-treated mice at day 11 (p < 0.05), whereas imatinib did not affect growth. Functional evaluation revealed that the contrast-enhanced area decreased significantly (p < 0.02) and by similar amounts under both anti-angiogenic treatments by day 8 (192 h): -23% for imatinib and -21% for sunitinib. No significant decrease was observed in the placebo group. Targeted contrast-enhanced imaging revealed lower differential targeted enhancement, that is, lower levels of VEGFR2 expression, in sunitinib-treated mice relative to placebo-treated mice from 24 h (p < 0.05) and relative to both placebo- and imatinib-treated mice from 48 h (p < 0.05). Histologic assessment of tumors after the final imaging indicated that necrotic area was significantly higher for the sunitinib group (21%) than for the placebo (8%, p < 0.001) and imatinib (11%, p < 0.05) groups. VEGFR2-targeted ultrasound was able to sensitively differentiate the anti-VEGFR2 effect from the reduced area of tumor with functional flow produced by both anti-angiogenic agents. BR55 molecular imaging was, thus, able both to detect early therapeutic response to sunitinib in CT26 tumors as soon as 24 h after the beginning of the treatment and to provide early discrimination (48 h) between tumor response during anti-angiogenic therapy targeting VEGFR2 expression and response during anti-angiogenic therapy not directly acting on this receptor.

Isolation of Foreign Material-Free Endothelial Progenitor Cells Using CD31 Aptamer and Therapeutic Application for Ischemic Injury

Endothelial progenitor cells (EPCs) can be isolated from human bone marrow or peripheral blood and reportedly contribute to neovascularization. Aptamers are 40-120-mer nucleotides that bind to a specific target molecule, as antibodies do. To utilize apatmers for isolation of EPCs, in the present study, we successfully generated aptamers that recognize human CD31, an endothelial cell marker. CD31 aptamers bound to human umbilical cord blood-derived EPCs and showed specific interaction with human CD31, but not with mouse CD31. However, CD31 aptamers showed non-specific interaction with CD31-negative 293FT cells and addition of polyanionic competitor dextran sulfate eliminated non-specific interaction without affecting cell viability. From the mixture of EPCs and 293FT cells, CD31 aptamers successfully isolated EPCs with 97.6% purity and 94.2% yield, comparable to those from antibody isolation. In addition, isolated EPCs were decoupled from CD31 aptamers with a brief treatment of high concentration dextran sulfate. EPCs isolated with CD31 aptamers and subsequently decoupled from CD31 aptamers were functional and enhanced the restoration of blood flow when transplanted into a murine hindlimb ischemia model. In this study, we demonstrated isolation of foreign material-free EPCs, which can be utilized as a universal protocol in preparation of cells for therapeutic transplantation.

PTK7+ Mononuclear Cells Express VEGFR2 and Contribute to Vascular Stabilization by Upregulating Angiopoietin-1

OBJECTIVE

In angiogenesis, circulating mononuclear cells are recruited to vascular lesions; however, the underlying mechanisms are poorly understood.

APPROACH AND RESULTS

Here, we characterize the functional role of protein tyrosine kinase 7 (PTK7)-expressing CD11b(+) mononuclear cells in vitro and in vivo using a mouse model of angiogenesis. Although the frequencies of PTK7(+)CD11b(+) cells in the bone marrow remained similar after vascular endothelial growth factor-A-induced neovascularization, we observed an 11-fold increase in the cornea. Importantly, vascular endothelial growth factor-A-induced chemotaxis of PTK7(+) cells was mediated by vascular endothelial growth factor receptor 2. In a coculture with endothelial cells, PTK7(+)CD11b(+) cells stabilized the vascular network for 2 weeks by expressing high levels of angiopoietin-1. The enhanced vascular stability was abolished by knockdown of angiopoietin-1 in PTK7(+)CD11b(+) cells and could be restored by angiopoietin-1 treatment.

CONCLUSIONS

We conclude that PTK7 expression in perivascular mononuclear cells induces vascular endothelial growth factor receptor 2 and angiopoietin-1 expression and thus contributes to vascular stabilization in angiogenesis.

Circulating hematopoietic and endothelial progenitor cells in newborn infants: effects of gestational age, postnatal age and clinical stress in the first 3 weeks of life

INTRODUCTION

Circulating endothelial progenitor cells (EPC) are bone marrow derived progenitors that can be mobilized by erythropoietin or in response to tissue injury, and participate in vascular repair. EPC are understudied in human neonates. Whether EPC frequency in newborn infants may be influenced by gestational age or postnatal stress is unknown.

METHODS

Blood samples were collected on day 1 of life and weekly for 3 weeks from hospitalized neonates for plasma erythropoietin and flow cytometry analysis for CD34+, CD34+CD45-, CD34+VEGFR2+ and CD34+CD45-VEGFR2+ cells (EPC). Associations between CD34+ cell subsets and clinical parameters were studied.

RESULTS

Forty five patients were enrolled. An inverse correlation with gestational age was observed for CD34+ and CD34+ VEGFR2+ cell frequencies in whole blood (WB) on day 1 (p<0.05). In preterm infants, CD34+ cell frequency decreased with increased postnatal age (p=0.0001) and CD34+VEGFR2+ cell frequency was higher at week 3 than on day 1 in WB (p=0.0002). On day one, CD34+ and CD34+CD45- cell frequencies in the mononuclear cell fraction (MNC) were higher in preterm than term infants (p=0.035 and p=0.049, respectively) but CD34+CD45-VEGFR2+ cell frequency (median 2.2/million MNC versus 3.8/million MNC) and erythropoietin levels were not significantly different. Transient increases in EPC were observed in five infants with infection. Four preterm infants who developed bronchopulmonary dysplasia had undetectable or low EPC through the first 3 weeks of life.

CONCLUSIONS

Gestational age and postnatal age influenced circulating CD34+ and CD34+VEGFR2+ but not CD34+CD45-VEGFR2+ (EPC) cell frequencies. Circulating EPC in neonates may be influenced by clinical stress.

Repertoire of endothelial progenitor cells mobilized by femoral artery ligation: a nonhuman primate study

To determine in the baboon model the identities and functional characteristics of endothelial progenitor cells (EPCs) mobilized in response to artery ligation, we collected peripheral blood mononuclear cells (PBMNCs) before and 3 days after a segment of femoral artery was removed. Our goal was to find EPC subpopulations with highly regenerative capacity. We identified 12 subpopulations of putative EPCs that were altered >1.75-fold; two subpopulations (CD146+/CD54-/CD45- at 6.63-fold, and CD146+/UEA-1-/CD45- at 12.21-fold) were dramatically elevated. To investigate the regenerative capacity of putative EPCs, we devised a new assay that maximally resembled their in vivo scenario, we purified CD34+ and CD146+ cells and co-cultured them with basal and mobilized PBMNCs; both cell types took up Dil-LDL, but purified CD146+ cells exhibited accelerated differentiation by increasing expression of CD31 and CD144, and by exhibiting more active cord-like structure formation by comparison to the CD34+ subpopulation in a co-culture with mobilized PBMNCs. We demonstrate that ischaemia due to vascular ligation mobilizes multiple types of cells with distinct roles. Baboon CD146+ cells exhibit higher reparative capacity than CD34+ cells, and thus are a potential source for therapeutic application.

Overexpression of angiopoietin-1 increases CD133+/c-kit+ cells and reduces myocardial apoptosis in db/db mouse infarcted hearts

Hematopoietic progenitor CD133(+)/c-kit(+) cells have been shown to be involved in myocardial healing following myocardial infarction (MI). Previously we demonstrated that angiopoietin-1(Ang-1) is beneficial in the repair of diabetic infarcted hearts. We now investigate whether Ang-1 affects CD133(+)/c-kit(+) cell recruitment to the infarcted myocardium thereby mediating cardiac repair in type II (db/db) diabetic mice. db/db mice were administered either adenovirus Ang-1 (Ad-Ang-1) or Ad-β-gal systemically immediately after ligation of the left anterior descending coronary artery (LAD). Overexpression of Ang-1 resulted in a significant increase in CXCR-4/SDF-1α expression and promoted CD133(+)/c-kit(+), CD133(+)/CXCR-4(+) and CD133(+)/SDF-1α(+) cell recruitment into ischemic hearts. Overexpression of Ang-1 led to significant increases in number of CD31(+) and smooth muscle-like cells and VEGF expression in bone marrow (BM). This was accompanied by significant decreases in cardiac apoptosis and fibrosis and an increase in myocardial capillary density. Ang-1 also upregulated Jagged-1, Notch3 and apelin expression followed by increases in arteriole formation in the infarcted myocardium. Furthermore, overexpression of Ang-1 resulted in a significant improvement of cardiac functional recovery after 14 days of ischemia. Our data strongly suggest that Ang-1 attenuates cardiac apoptosis and promotes cardiac repair by a mechanism involving in promoting CD133(+)/c-kit(+) cells and angiogenesis in diabetic db/db mouse infarcted hearts.

Mobilization of hematopoietic stem/progenitor cells: general principles and molecular mechanisms

Hematopoietic stem/progenitor cell mobilization can be achieved by a variety of bone marrow niche modifications, although efficient mobilization requires simultaneous expansion of the stem/progenitor cell pool and niche modification. Many of the mechanisms involved in G-CSF-induced mobilization have been described. With regard to mobilization of hematopoietic stem/progenitor cells, challenges for the future include the analysis of genetic factors responsible for the great variability in mobilization responses, and the identification of predictors of mobilization efficiency, as well as the development of mobilizing schemes for poor mobilizers. Moreover, improved regimens for enhanced or even preferential mobilization of nonhematopoietic stem/progenitor cell types, and their therapeutic potential for endogenous tissue repair will be questions to be vigorously pursued in the near future.

Unicentric study of cell therapy in chronic obstructive pulmonary disease/pulmonary emphysema

Within the chronic obstructive pulmonary disease (COPD) spectrum, lung emphysema presents, as a primarily histopathologic feature, the destruction of pulmonary parenchyma and, accordingly, an increase in the airflow obstruction distal to the terminal bronchiole. Notwithstanding the significant advances in prevention and treatment of symptoms, no effective or curative therapy has been accomplished. In this context, cellular therapy with stem cells (SCs) arises as a new therapeutic approach, with a wide application potential. The purpose of this study is to evaluate the safety of SCs infusion procedure in patients with advanced COPD (stage IV dyspnea). After selection, patients underwent clinical examination and received granulocyte colony-stimulating factor, immediately prior to the bone marrow harvest. The bone marrow mononuclear cells (BMMC) were isolated and infused into a peripheral vein. The 12-month follow-up showed a significant improvement in the quality of life, as well as a clinical stable condition, which suggest a change in the natural process of the disease. Therefore, the proposed methodology in this study for BMMC cell therapy in sufferers of advanced COPD was demonstrated to be free of significant adverse effects. Although a larger sample and a greater follow-up period are needed, it is possible to infer that BMMC cell therapy introduces an unprecedented change in the course or in the natural history of emphysema, inhibiting or slowing the progression of disease. This clinical trial was registered with ClinicalTrials.gov (NCT01110252) and was approved by the Brazilian National Committee of Ethics in Research (registration no. 14764, CONEP report 233/2009).

Bone marrow and circulating stem/progenitor cells for regenerative cardiovascular therapy

Cardiovascular disease is the leading cause of death and disability in the Western world. In addition to the advancement of current therapeutic approaches to reduce the associated morbidity and mortality, regenerative medicine and cell-based therapy have been areas of continuous investigation. Circulating and bone-marrow-derived stem or endothelial progenitor cells are an attractive source for regenerative therapy in the cardiovascular field. In this review, we highlight the advantages and limitations of this approach with a focus on key observations from animal studies and clinical trials.