Red blood cell contamination of the final cell product impairs the efficacy of autologous bone marrow mononuclear cell therapy

The Impact of Centrifugal Force on Isolation of Bone Marrow Mononuclear Cells Using Density Gradient Centrifugation

BACKGROUND

Bone marrow mononuclear cells (BMMNCs) have great potential in bone regenerative therapy. The main method used today to obtain BMMNCs is Ficoll density gradient centrifugation. However, the centrifugal force for this isolation method is still suboptimal.

OBJECTIVES

To determine the optimal centrifugal force in Ficoll density gradient centrifugation of bone marrow (BM) to achieve high stem/progenitor cell content BMMNCs for regenerative therapy.

METHODS

BM was aspirated from nine minipigs and divided into three groups according to different centrifugal forces (200 g, 300 g and 400 g). Immediately after BMMNCs were obtained from each group by Ficoll density gradient centrifugation, residual red blood cell (RBC) level, nucleated cell counting, viability and flow cytometric analyses of apoptosis and reactive oxygen species (ROS) generation were measured. The phenotypic CD90 and colony formation analyses of BMMNCs of each group were performed as well. Bone marrow-derived mesenchymal stem cells (BMSCs) were harvested at passage 2, then morphology, cell phenotype, proliferation, adipogenic, chondrogenic and osteogenic lineage differentiation potential of BMSCs from each group were compared.

RESULTS

The 300 g centrifugal force was able to isolate BMMNCs from BM with the same efficiency as 400 g and provided significantly higher yields of CD90+ BMSCs and fibroblastic colony-forming units of BMSC (CFU-f(BMSC)), which is more crucial for the regenerative efficacy of BMMNCs. Meanwhile, 200 g hosted the most RBC contamination and minimum CFU-f (BMSC) yield, which will be disadvantageous for BMMNC-based cell therapy. As for in vitro cultured BMSCs which were isolated from BMMNCs by different centrifugal forces, no significant differences were found on morphology, cell proliferation rate, phenotypic marker, adipogenic, chondrogenic and osteogenic differentiation potential.

CONCLUSIONS

300 g may be the optimal centrifugal force when using Ficoll density gradient centrifugation to isolate BMMNCs for bone regenerative therapy.

NO LEVEL ASSIGNED

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Different methods of bone marrow harvesting influence cell characteristics and purity, affecting clinical outcomes

Background

Bone marrow (BM)-derived stem cells were implanted to induce angiogenesis in patients with no-option critical limb-threatening ischemia. Considering the potential for this therapy, conflicting results related to BM harvesting methods have been reported that could affect stem cell concentrations and quality.

Methods

A total of 75 patients with no-option critical limb-threatening ischemia were treated with BM implantation. For 58 patients, BM was harvested using a BM aspirate concentrate system (Harvest Technologies; group HT) with a standard aspiration needle, followed by an automated centrifugation process, to produce BM aspirate concentrate. For 17 patients, BM was harvested using the Marrow Cellution system (Aspire Medical Innovation; group MC). CD34+ cells/mL, CD117+ cells/mL, CD133+ cells/mL, CD309+ cells/mL, hematocrit, and BM purity were compared between the two BM preparations.

Results

The retrospective analysis of a subset group after adjustment for age shows that the quality of BM obtained using the Marrow Cellution system is better, in terms of purity, than the classic harvesting method before centrifugation. Harvested BM before centrifugation is characterized by a higher percentage of CD133+ cells compared with BM after centrifugation. In contrast, the MC aspirate had a larger amount of very small embryonic-like cells, as indicated by the higher percentage of CD133+, CD34+, and CD45- cells. These differences translated into an increased occurrence of leg amputations in group HT than in group MC and an increase in transcutaneous oxygen pressure in patients treated with BM aspirated using MC.

Conclusions

BM manipulation, such as centrifugation, affects the quality and number of stem cells, with detrimental consequences on clinical outcomes, as reflected by the different amputation rates between the two groups.

Opportunities and challenges in stem cell therapy in cardiovascular diseases: Position standing in 2022

This study intends to evaluate the development, importance, pre-clinical and clinical study evaluation of stem cell therapy for the treatment of cardiovascular disease. Cardiovascular disease is one of the main causes of fatality in the whole world. Though there are great progressions in the pharmacological and other interventional treatment options, heart diseases remain a common disorder that causes long-term warnings. Recent accession promotes the symptoms and slows down the adverse effects regarding cardiac remodelling. But they cannot locate the problems of immutable loss of cardiac tissues. In this case, stem cell treatment holds a promising challenge. Stem cells are the cells that are capable of differentiating into many cells according to their needs. So, it is assumed that these cells can distinguish into many cells and if these cells can be individualized into cardiac cells then they can be used to replace the damaged tissues of the heart. There is some abridgment in this therapy, none the less stem cell therapy remains a hopeful destination in the treatment of heart disease.

Quality Control Platform for the Standardization of a Regenerative Medicine Product

Adipose tissue is an attractive source of stem cells due to its wide availability. They contribute to the stromal vascular fraction (SVF), which is composed of pre-adipocytes, tissue-progenitors, and pericytes, among others. Because its direct use in medical applications is increasing worldwide, new quality control systems are required. We investigated the ability of the Non-Equilibrium Earth Gravity Assisted Dynamic Fractionation (NEEGA-DF) method to analyze and separate cells based solely on their physical characteristics, resulting in a fingerprint of the biological sample. Adipose tissue was enzymatically digested, and the SVF was analyzed by NEEGA-DF. Based on the fractogram (the UV signal of eluting cells versus time of analysis) the collection time was set to sort alive cells. The collected cells (F-SVF) were analyzed for their phenotype, immunomodulation ability, and differentiation potential. The SVF profile showed reproducibility, and the alive cells were collected. The F-SVF showed intact adhesion phenotype, proliferation, and differentiation potential. The methodology allowed enrichment of the mesenchymal component with a higher expression of mesenchymal markers and depletion of debris, RBCs, and an extracellular matrix still present in the digestive product. Moreover, cells eluting in the last minutes showed higher circularity and lower area, proving the principles of enrichment of a more homogenous cell population with better characteristics. We proved the NEEGA-DF method is a “gentle” cell sorter that purifies primary cells obtained by enzymatic digestion and does not alter any stem cell function.

Effective Label-Free Sorting of Multipotent Mesenchymal Stem Cells from Clinical Bone Marrow Samples

Mesenchymal stem cells (MSC) make up less than 1% of the bone marrow (BM). Several methods are used for their isolation such as gradient separation or centrifugation, but these methodologies are not direct and, thus, plastic adherence outgrowth or magnetic/fluorescent-activated sorting is required. To overcome this limitation, we investigated the use of a new separative technology to isolate MSCs from BM; it label-free separates cells based solely on their physical characteristics, preserving their native physical properties, and allows real-time visualization of cells. BM obtained from patients operated for osteochondral defects was directly concentrated in the operatory room and then analyzed using the new technology. Based on cell live-imaging and the sample profile, it was possible to highlight three fractions (F1, F2, F3), and the collected cells were evaluated in terms of their morphology, phenotype, CFU-F, and differentiation potential. Multipotent MSCs were found in F1: higher CFU-F activity and differentiation potential towards mesenchymal lineages compared to the other fractions. In addition, the technology depletes dead cells, removing unwanted red blood cells and non-progenitor stromal cells from the biological sample. This new technology provides an effective method to separate MSCs from fresh BM, maintaining their native characteristics and avoiding cell manipulation. This allows selective cell identification with a potential impact on regenerative medicine approaches in the orthopedic field and clinical applications.

Red blood cells and their releasates compromise bone marrow-derived human mesenchymal stem/stromal cell survival in vitro

PURPOSE

The use of bone marrow aspirate (BMA) and bone marrow aspirate concentrate (BMC) in the treatment of inflammatory orthopedic conditions has become a common practice. The therapeutic effect of BMA/BMC is thought to revolve primarily around the mesenchymal stem/stromal cell (MSC) population residing within the nucleated cell fraction. MSCs have the unique ability to respond to site of injury via the secretion of immunomodulating factors, resolving inflammation in diseased joints. Recently, the importance of hematocrit (HCT) in BMC has been debated, as the potential impact on MSC function is unknown. In the present study, we investigate MSC health over a short time-course following exposure to a range of HCT and red blood cell releasate (RBC_rel) conditions.

METHODS

Bone marrow-derived human MSCs in early passage were grown under conditions of 0%, 2.5%, 5%, 10%, 20% and 40% HCT and RBC_rel conditions for 3 days. At each day, the percentage of viable, apoptotic and necrotic MSCs was determined via flow cytometry. Relative viable MSC counts in each condition was determined to account for dynamic changes in overall MSC densities over the time-course. Statistical analysis was performed using a one-way ANOVA comparing test conditions to the control followed by a Dunnett's multiple comparison test.

RESULTS

Significant reductions in viable MSCs concurrent with an increase in necrotic MSCs in high HCT and RBC_rel conditions was observed within 24 h. At each successive timepoint, the percent and relative number of viable MSCs were reduced, becoming significant in multiple HCT and RBC_rel conditions by Day 3. Necrosis appears to be the initial mode of MSC death following exposure to HCT and RBC_rel, followed by apoptosis in surviving MSC fractions.

CONCLUSION

Various levels of HCT and RBC_rel severely compromise MSC health within 3 days and HCT should be controlled in the preparation of BMC products. Further, HCT of BMCs should be routinely recorded and tracked with patient outcomes along with routine metrics (e.g. nucleated cell counts, fibroblast-colony forming units). Differences in HCT may account for the inconsistencies in the efficacy of BMC reported when treating orthopedic conditions.

Recommendations for Nomenclature and Definition Of Cell Products Intended for Human Cardiovascular Use

Exogenous cell-based therapy has emerged as a promising new strategy to facilitate repair of hearts damaged by acute or chronic injury. However, the field of cell-based therapy is handicapped by the lack of standardized definitions and terminology, making comparisons across studies challenging. Even the term "stem cell therapy" is misleading because only a small percentage of cells derived from adult bone marrow, peripheral blood, or adipose tissue meets the accepted hematopoietic or developmental definition of stem cells. Furthermore, cells (stem or otherwise) are dynamic biological products, meaning that their surface marker expression, phenotypic and functional characteristics, and the products they secrete in response to their microenvironment can change. It is also important to point out that most surface markers are seldom specific for a cell type. In this article, we discuss the lack of consistency in the descriptive terminology used in cell-based therapies and offer guidelines aimed at standardizing nomenclature and definitions to improve communication among investigators and the general public.

The efficacy of bone marrow mononuclear stem cell transplantation in patients with non-ischemic dilated cardiomyopathy-a meta analysis

Cardiomyopathy refers to a wide spectrum of heart pathologies that interfere with normal heart function. Management options of patients with cardiomyopathy depended mainly on the severity of the condition. Lifestyle modifications and regular exercise together with a healthy diet is compatible for mild conditions. Severe conditions, however, rely on medications or surgery. Here, we aim to investigate the efficacy of bone marrow mononuclear stem cell transplantation in patients with dilated cardiomyopathy. We searched PubMed, Scopus, and Cochrane CENTRAL for relevant clinical trials and excluded observational studies. We performed the quality assessment of this study following GRADE guidelines. The assessment of the risk of bias was performed by the Cochrane's risk of bias tool. We present an analysis of the following outcomes: left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), and six minutes walking test. Data were pooled as mean differences (MD) and relative confidence intervals (CI). The analysis of 667 patients from 11 studies receiving autologous bone marrow cell therapy for non-ischemic dilated cardiomyopathy is presented. A total of 338 patients were allocated to the treatment group, and 329 participants entered the control group. The mean age of the patients in the treatment group is 52.4 ± 4.3 years, while that of the control is 53.7 ± 3.7 years. Seven studies (14.18-23) reported transplantation through the intracoronary route. Table 1 shows a summary of the baseline characteristics of the included studies and participants, the number of injected cells, and the type of injected cells in each trial. Table 2 summarizes and illustrates the previous treatment history of included patients in each trial, as well as the baseline values of different scores used as outcome measures in this analysis. We found that bone marrow mononuclear stem cell therapy leads to significantly increased LVEF (MD = 4.54%, 95% CI [3.52, 5.56], P < 0.0001). Patients in the transplant group experienced less left ventricular end-diastolic diameter (millimeter) than the control arm (MD = -1.86 mm, 95% CI [-4.01, 0.29], P = 0.09). Additionally, Patients in the transplant group could walk 28.53 m more than the controls (MD = 28.53 m, 95% CI [2.51, 54.55], P = 0.03). Transplantation of bone marrow stem cells yields acceptable results regarding left ventricular ejection fraction and lowers the left ventricular end-diastolic diameter. Additionally, the six minutes walking test is improved in the transplant group. Table 1 Demographic data about the included participants Study Year Sample size Age, years Males, n (%) Diabetics, n (%) Route of administration Number of injected cells Type of injected cells TTT Control TTT Control TTT Control TTT Control Bartolucci 2015 12 11 58 ± 14 57 ± 11 8 (66.7) 9 (81.8) 2 (16.7) 1 (9.1) Intracoronary 1.94 × 10^6 CD34 +  Bocchi 2010 8 15 51 ± 15 NR NR NR NR Intracoronary NR NR Frljak 2018 30 30 56 ± 9 54 ± 11 27 (90) 26 (87) 3 (10) 2 (6) Trans-endocardial NR CD34 +  Hamshere 2015 15 14 57.67 ± 12.32 56.79 ± 9.8 10 12 9(59.9%) 8(57.1%) Intracoronary 4.91 × 10^6 CD34 +  Hu 2011 31 29 56.61 ± 9.72 58.27 ± 8.86 NR NR NR NR NR NR NR Matrino 2015 82 78 51 ± 11.1 49.6 ± 11.1 73.1 68.3 NR NR Intracoronary 10^8 TTT, CD45, CD105, and CD133 Sant'Anna 2014 20 10 48.3 ± 8.71 51.6 ± 7.79 13(65) 5 (50%) NR NR Intra-myocardial 1.06 × 108 CD3, CD4, CD14, CD34, CD38, and CD45 Seth 2010 41 40 45 ± 15 49 ± 9 33 35 NR NR NR 168 × 10^6 Bone marrow mononuclear cells Vrtovec 2011 28 27 52 ± 8 54 ± 7 26 (93) 23 (85) NR NR Intracoronary 123 × 10^6 CD34 +  Vrtovec 2013 55 55 53 ± 8 55 ± 7 45 (82) 44 (80) NR NR Intracoronary NR NR Xiao 2017 16 20 49.5 ± 11.6 54.4 ± 11.6 9 (56.3) 14 (70.0) 6 (37.5) 5 (29.4) Intracoronary infusion (4.9 ± 1.7) × 108 (CD29, CD34, CD44, CD45, and CD166) Data are reported as mean ± SD or n (%) unless proved otherwise TTT treatment group, NR not reported Table 2 Previous history of treatment and drug intake by the patients Study Year Medical therapy, n (%) Baseline scores, mean (SD) Beta blockers ACE inhibitors Digoxin Diuretics LVEF, % LVEDD, mm Six minutes-walk test^* TTT Control TTT Control TTT Control TTT Control TTT Control TTT Control TTT Control Bartolucci 2015 10 (83.3) 8 (72.7) NR NR 3 (25) 3 (27.3) 11 (91.6) 10 (90.9) 26.8 ± 4.9 30.3 ± 6.3 NR NR NR NR Bocchi 2010 NR NR NR NR NR NR NR NR 21.8 ± 3.8 30.6 ± 7.3 79 (10) 78 (12) NR NR Frljak 2018 30 (100) 30 (100) 31 (100) 32 (100) 2 (7) 3 (10) 32 (100) 33 (100) 32.2 ± 9.3 31.1 ± 7.8 NR NR NR NR Hamshere 2015 13 14 15 13 6 2 9 8 32.93 ± 16.46 29.75 ± 9.2 NR NR NR NR Hu* 2011 NR NR NR NR NR NR NR NR NR NR NR NR 466 (402, 495) 448 (383, 497) Matrino 2015 9 (11) 8 (10.2) 53 (64.1) 48 (61.1) 63 (77) 62 (79) 74 (89.7) 69 (88.9) 23.8 ± 7.2 24.7 ± 7.0 NR NR 347.3(146.7) 349.8(139.7) Sant'Anna 2014 NR NR NR NR NR NR NR NR NR NR NR NR 358.5 (88.69) 353 (86.67) Seth 2010 29 (70) 29 (72) 41 (100) 40 (100) NR NR NR NR NR NR NR NR NR NR Vrtovec 2011 21 (75) 22 (81) NR NR 5 (18) 6 (22) 26 (93) 24 (88) 25.6 ± 5.1 26.7 ± 3.9 69 ± 10 70 ± 7 NR NR Vrtovec 2013 43 (79) 46 (84) 51 (93) 54 (98) 9 (16) 11 (20) 51 (93) 20 (91) 24.3 ± 6.5 25.7 ± 4.1 69 ± 10 70 ± 7 NR NR Xiao 2017 16 (100) 20 (100) 16 (100) 19 (95) 4 (25.0) 8 (40.0) 5 (31.3) 6 (30.0) 33.1 ± 3.9 33.7 ± 4.0 NR NR 355.0 ± 91.2 323.3 ± 89.4 Data are reported as mean ± SD or n (%) unless proved otherwise TTT treatment group, NR not reported ^*Data are reported as median (IQR).

Impaired therapeutic efficacy of bone marrow cells from post-myocardial infarction patients in the TIME and LateTIME clinical trials

Implantation of bone marrow-derived cells (BMCs) into mouse hearts post-myocardial infarction (MI) limits cardiac functional decline. However, clinical trials of post-MI BMC therapy have yielded conflicting results. While most laboratory experiments use healthy BMC donor mice, clinical trials use post-MI autologous BMCs. Post-MI mouse BMCs are therapeutically impaired, due to inflammatory changes in BMC composition. Thus, therapeutic efficacy of the BMCs progressively worsens after MI but recovers as donor inflammatory response resolves. The availability of post-MI patient BM mononuclear cells (MNCs) from the TIME and LateTIME clinical trials enabled us to test if human post-MI MNCs undergo a similar period of impaired efficacy. We hypothesized that MNCs from TIME trial patients would be less therapeutic than healthy human donor MNCs when implanted into post-MI mouse hearts, and that therapeutic properties would be restored in MNCs from LateTIME trial patients. Post-MI SCID mice received MNCs from healthy donors, TIME patients, or LateTIME patients. Cardiac function improved considerably in the healthy donor group, but neither the TIME nor LateTIME group showed therapeutic effect. Conclusion: post-MI human MNCs lack therapeutic benefits possessed by healthy MNCs, which may partially explain why BMC clinical trials have been less successful than mouse studies.

Determination of the effective dose of bone marrow mononuclear cell therapy for bone healing in vivo

Introduction

Cell-based therapy by bone marrow mononuclear cells (BMC) in a large-sized bone defect has already shown improved vascularization and new bone formation. First clinical trials are already being conducted. BMC were isolated from bone marrow aspirate and given back to patients in combination with a scaffold within some hours. However, the optimal concentration of BMC has not yet been determined for bone healing. With this study, we want to determine the optimal dosage of the BMC in the bone defect to support bone healing.

Material and methods

Scaffolds with increasing BMC concentrations were inserted into a 5 mm femoral defect, cell concentrations of 2 × 10⁶ BMC/mL, 1 × 10⁷ BMC/mL and 2 × 10⁷ BMC/mL were used. Based on the initial cell number used to colonize the scaffolds, the groups are designated 1 × 10⁶, 5 × 10⁶ and 1 × 10⁷ group. Bone healing was assessed biomechanically, radiologically (µCT), and histologically after 8 weeks healing time.

Results

Improved bone healing parameters were noted in the 1 × 10⁶ and 5 × 10⁶ BMC groups. A significantly higher BMD was observed in the 1 × 10⁶ BMC group compared to the other groups. Histologically, a significantly increased bone growth in the defect area was observed in group 5 × 10⁶ BMC. This finding could be supported radiologically.

Conclusion

It was shown that the effective dose of BMC for bone defect healing ranges from 2 × 10⁶ BMC/mL to 1 × 10⁷ BMC/mL. This concentration range seems to be the therapeutic window for BMC-supported therapy of large bone defects. However, further studies are necessary to clarify the exact BMC-dose dependent mechanisms of bone defect healing and to determine the therapeutically effective range more precisely.

State of the art of stem cell therapy for ischaemic cardiomyopathy. Part 2

Ischemic cardiomyopathy is becoming a leading cause of morbidity and mortality in the whole world. Stem cell-based therapy is emerging as a promising option for treatment of ischemic cardiomyopathy. Several stem cell types, including cardiac-derived stem cells, bone marrow-derived stem cells, mesenchymal stem cells, skeletal myoblasts, CD34+ and CD133+ stem cells have been used in clinical trials. Clinical effects mostly depend on transdifferentiation and paracrine factors. One important issue is that a low survival and residential rate of transferred stem cells blocks the effective advances in cardiac improvement. Many other factors associated with the efficacy of cell replacement therapy for ischemic cardiomyopathy mainly including the route of delivery, the type and number of stem cell infusion, the timing of injection, patient's physical conditions, the particular microenvironment onto which the cells are delivered, and clinical conditions remain to be addressed. Here we provide an overview of modern methods of stem cell delivery, types of stem cells and discuss the current state of their therapeutic potential.

Evaluation of post-thaw CFU-GM: clinical utility and role in quality assessment of umbilical cord blood in patients receiving single unit transplant

BACKGROUND

The CFU assay is considered the only in vitro assay that assesses the biologic function of hematopoietic stem and progenitor cells (HSPC).

STUDY DESIGN AND METHODS

To investigate the impact of post-thaw CFU-GM counts on the quality of umbilical cord blood (UCB), we studied transplant outcomes in 269 patients receiving single UCB transplant. We also correlated the post-thaw CFU-GM counts of 1912 units with the pre-freeze and post-thaw graft characteristics, hoping to optimize selection criteria of UCB. Data analysis included: total nucleated cells, viability, CD34+, nucleated red blood cells (NRBC), hematocrit, frozen storage time, and cord blood bank (CBB).

RESULTS

We demonstrated an association between post-thaw CFU-GM dose and the speed of neutrophil and platelet engraftment (p < 0.01). Higher post-thaw CFU-GM dose showed an increased benefit for neutrophil and platelet engraftment (p < 0.01). Post-thaw CD34+ cell dose and CFU-GM dose were strongly correlated (r = 0.78). However, CFU-GM dose showed additional benefit for patients receiving the lowest quartile of CD34+ dose. HLA disparity did not adversely impact either neutrophil or platelet engraftment. Post-thaw CFU-GM/million nucleated cells plated showed moderate correlation with pre-freeze and post-thaw CD34+ and weak correlation with other parameters. Post-thaw CFU-GM was not influenced by storage time, but was impacted by the CBB from which the unit is obtained (p < 0.01).

CONCLUSION

Post-thaw CFU-GM is an effective measure of the quality and efficacy of the UCB graft, particularly adding valuable clinical information when the CD34+ cell dose is low. Consideration of pre-freeze CD34+ cell content and CBB as additional selection criteria is warranted.

Human Leukocyte Antigen and Red Blood Cells Impact Umbilical Cord Blood CD34+ Cell Viability after Thawing

Hematopoietic progenitor cell (HPC) transplantation is a treatment option for malignant and nonmalignant diseases. Umbilical cord blood (UCB) is an important HPC source, mainly for pediatric patients. It has been demonstrated that human leukocyte antigen (HLA) matching and cell dose are the most important features impacting clinical outcomes. However, UCB matching is performed using low resolution HLA typing and it has been demonstrated that the unnoticed mismatches negatively impact the transplant. Since we found differences in CD34+ viability after thawing of UCB units matched for two different patients (p = 0.05), we presumed a possible association between CD34+ cell viability and HLA. We performed a multivariate linear model (n = 67), comprising pre-cryopreservation variables and high resolution HLA genotypes separately. We found that pre-cryopreservation red blood cells (RBC), granulocytes, and viable CD34+ cell count significantly impacted CD34+ viability after thawing, along with HLA-B or -C (R2 = 0.95, p = 0.01; R2 = 0.56, p = 0.007, respectively). Although HLA-B*40:02 may have a negative impact on CD34+ cell viability, RBC depletion significantly improves it.

The role of stem cells in treating coronary artery disease in 2018

The last decade has witnessed the publication of a number of stem cell clinical trials, primarily using bone marrow-derived cells as the injected cell. Much has been learned through these "first-generation" clinical trials. The advances in our understanding include the following: (1) cell therapy is safe; (2) cell therapy has been mildly effective; and (3) human bone marrow-derived stem cells do not transdifferentiate into cardiomyocytes or new blood vessels. The primary mechanism of action for cell therapy is now believed to be through paracrine effects that include the release of cytokines, chemokines, and growth factors that inhibit apoptosis and fibrosis, enhance contractility, and activate endogenous regenerative mechanisms through endogenous circulating or site-specific stem cells. The current direction for clinical trials includes the use of stem cells capable of cardiac lineage.

A rapid and efficient method for the isolation of postnatal murine cardiac myocyte and fibroblast cells

The capacity to isolate and study single cardiomyocytes has dramatically enhanced our understanding of the fundamental mechanisms of the heart. Currently, 2 primary methods for the isolation of cardiomyocytes are employed: (i) the neonatal isolation protocol and (ii) the Langendorff isolation method. A major limiting feature of both procedures is the inability to isolate cardiomyocytes between 3 days and 3 weeks after birth. Herein, we report the establishment and validation of a new method for the rapid and efficient isolation of mouse cardiomyocytes, regardless of age. This novel procedure utilizes whole heart perfusion of a trypsin–collagenase Krebs-based buffer through the left ventricle at a high flow rate. Cardiomyocytes can be isolated in significantly less time with a simple, syringe-pump-based apparatus. Typically, we can digest 10–15 hearts per hour. Altogether, we have established an efficient and reproducible method for the rapid isolation of fresh cardiomyocytes from postnatal mouse hearts of any age.

Single-step enrichment of basophils from human peripheral blood by a novel method using a Percoll density gradient

We have developed a novel continuous flow-through cell separation method using a Percoll density gradient. This method can continuously separate a large number of cells into five fractions according to their densities. To apply this method to the separation of basophils, Percoll density gradients were modified to improve basophil enrichment. When a set of Percoll density gradients was prepared (1.071, 1.075, 1.080, 1.084, and 1.090 g/mL) the basophils in a healthy volunteer were enriched by an average of 23.1 and 63.5% at Percoll densities of 1.075 (fraction 3) and 1.080 g/mL (fraction 4), respectively. On average, the yield of basophils was 1.66 × 10(5) cells in fraction 3 and 1.61 × 10(5) cells in fraction 4 from 9 mL of peripheral blood. The expression of CD203c (cluster of differentiation 203c) on separated basophils was upregulated by anti-immunoglobulin E stimulation similar to basophils in whole blood. Histamine release induced by calcium ionophore was also observed in the separated basophils. The present method will be useful for basophil enrichment since it preserves their function without using counterflow elutriation and immunological reagents, and this method will be effective as a preparative separation for cell purification by flow cytometry.

Ammonium-Chloride-Potassium Lysing Buffer Treatment of Fully Differentiated Cells Increases Cell Purity and Resulting Neotissue Functional Properties

Juvenile and fetal, primary, fully differentiated cells are widely considered to be ideal cell types for tissue engineering applications. However, their use in tissue engineering may be hindered through contamination by undesirable cell types. These include blood-associated cells as well as unwanted resident cell types found both in healthy and pathologic donor tissues. Ammonium-chloride-potassium (ACK) lysing buffer is used to lyse red blood cells (RBCs) during the isolation of stem cell populations, but has not been explored for the purification of fully differentiated cells. This study sought to investigate the effect of ACK buffer treatment of freshly isolated, fully differentiated cells to increase cell purity and enhance the formation of biofunctional engineered neotissues; this was tested in the well-established cartilage tissue engineering model of the self-assembling process using fetal ovine articular chondrocytes (foACs) and juvenile bovine articular chondrocytes (jbACs). ACK buffer treatment of foACs and jbACs decreased the number of contaminating RBCs by over 60% and additionally reduced the number of apoptotic chondrocytes in the cell isolates. Reducing the number of contaminating RBCs removed cellular detractors to the self-assembling process and eliminated an apoptotic stimulus, thus improving neocartilage homogeneity, chondrocyte distribution, and extracellular matrix deposition within the neotissues. For example, in foAC neocartilage, ACK buffer treatment ultimately led to a 170% increase in compressive aggregate modulus, a 130% increase in shear modulus, an 80% increase in tensile modulus, and a 130% increase in ultimate tensile strength of the neocartilage. This work represents the first time that ACK buffer has been used to purify fully differentiated cells and subsequently increase the functional properties of neotissue.

Autologous Bone Marrow Mononuclear Cell Implantation and Its Impact on the Outcome of Patients With Critical Limb Ischemia - Results of a Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Cell therapy is a therapeutic option for patients presenting with nonrevascularizable critical limb ischemia (CLI). However there is a lack of firm evidence on its efficacy because of the paucity of randomized controlled trials.Methods and Results:The BALI trial was a multicenter, randomized, controlled, double-blind clinical trial that included 38 patients. For all of them, 500 mL of bone marrow were collected for preparation of a BM-MNC product that was implanted in patients assigned to active treatment. For the placebo group, a placebo cell-free product was implanted. Within 6 months after inclusion, major amputations had to be performed in 5 of the 19 placebo-treated patients and in 3 of the 17 BM-MNC-treated patients. According to a classical logistic regression analysis there was no significant difference. However, when using the jackknife analysis, 6 months after inclusion BM-MNC implantation was associated with a lower risk of major amputation (odds ratio (OR): 0.55; 95% confidence interval (CI): 0.52-0.58; P<0.0001) and of occurrence of any event (major or minor amputation, or revascularization) (OR: 0.30; 95% CI: 0.29-0.31; P<0.0001). The secondary endpoints (i.e., pain, ulcers, TcPO₂, and ankle-brachial index value) were not statistically different between groups.

CONCLUSIONS

Our results suggested that cell therapy reduced the risk of major amputation in patients presenting with nonrevascularizable CLI.

Evaluation of bone marrow mononuclear cells as an adjunct therapy to minced muscle graft for the treatment of volumetric muscle loss injuries

BACKGROUND

The delivery of alternative myogenic cell sources to enhance the efficacy of minced muscle grafts (MG) for the treatment of volumetric muscle loss (VML) injuries is a promising strategy to overcome the demand on muscle-derived donor tissue that currently limits the translation of this therapy.

METHODS

Using a rat model of VML, bone marrow mononuclear cells (BMNCs) were evaluated for their ability to directly contribute to de novo muscle fiber regeneration by transplanting MG in a collagen carrier at a dose of 50% of the VML injury both with and without concomitant delivery of 5 million BMNCs derived via density gradient centrifugation from the bone marrow of a syngeneic green fluorescent protein (GFP)⁺ donor.

RESULTS

Histological, molecular, and functional analyses revealed that BMNCs can engraft with co-delivered MG and contribute to nascent myofiber, but do so at a low magnitude without resulting in significant changes to transcription of key myogenic genes or gains in whole muscle force generation relative to MG alone.

CONCLUSION

As such, co-delivery of BMNCs with MG is a promising treatment paradigm to VML that will require further investigation to identify the phenotype and therapeutic dosing of the bone marrow-derived cell populations which engraft most efficiently.

Cell therapy for heart disease after 15 years: Unmet expectations

Over the past two decades cardiac cell therapy (CCT) has emerged as a promising new strategy to cure heart diseases at high unmet need. Thousands of patients have entered clinical trials for acute or chronic heart conditions testing different cell types, including autologous or allogeneic bone marrow (BM)-derived mononuclear or selected cells, BM- or adipose tissue-derived mesenchymal cells, or cardiac resident progenitors based on their potential ability to regenerate scarred or dysfunctional myocardium. Nowadays, the original enthusiasm surrounding the regenerative medicine field has been cushioned by a cumulative body of evidence indicating an inefficient or modest efficacy of CCT in improving cardiac function, along with the continued lack of indisputable proof for long-term prognostic benefit. In this review, we have firstly comprehensively outlined the positive and negative results of cell therapy studies in patients with acute myocardial infarction, refractory angina and chronic heart failure. Next, we have discussed cell therapy- and patient-related variables (e.g. cell intrinsic and extrinsic characteristics as well as criteria of patient selection and proposed methodologies) that might have dampened the efficacy of past cell therapy trials. Finally, we have addressed critical factors to be considered before embarking on further clinical trials.

GMP-conformant on-site manufacturing of a CD133+ stem cell product for cardiovascular regeneration

Background

CD133⁺ stem cells represent a promising subpopulation for innovative cell-based therapies in cardiovascular regeneration. Several clinical trials have shown remarkable beneficial effects following their intramyocardial transplantation. Yet, the purification of CD133⁺ stem cells is typically performed in centralized clean room facilities using semi-automatic manufacturing processes based on magnetic cell sorting (MACS®). However, this requires time-consuming and cost-intensive logistics.

Methods

CD133⁺ stem cells were purified from patient-derived sternal bone marrow using the recently developed automatic CliniMACS Prodigy® BM-133 System (Prodigy). The entire manufacturing process, as well as the subsequent quality control of the final cell product (CP), were realized on-site and in compliance with EU guidelines for Good Manufacturing Practice. The biological activity of automatically isolated CD133⁺ cells was evaluated and compared to manually isolated CD133⁺ cells via functional assays as well as immunofluorescence microscopy. In addition, the regenerative potential of purified stem cells was assessed 3 weeks after transplantation in immunodeficient mice which had been subjected to experimental myocardial infarction.

Results

We established for the first time an on-site manufacturing procedure for stem CPs intended for the treatment of ischemic heart diseases using an automatized system. On average, 0.88 × 10⁶ viable CD133⁺ cells with a mean log₁₀ depletion of 3.23 ± 0.19 of non-target cells were isolated. Furthermore, we demonstrated that these automatically isolated cells bear proliferation and differentiation capacities comparable to manually isolated cells in vitro. Moreover, the automatically generated CP shows equal cardiac regeneration potential in vivo.

Conclusions

Our results indicate that the Prodigy is a powerful system for automatic manufacturing of a CD133⁺ CP within few hours. Compared to conventional manufacturing processes, future clinical application of this system offers multiple benefits including stable CP quality and on-site purification under reduced clean room requirements. This will allow saving of time, reduced logistics and diminished costs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0467-0) contains supplementary material, which is available to authorized users.

Hetrombopag, a Thrombopoietin Receptor Agonist, Protects Cardiomyocyte Survival from Oxidative Stress Damage as an Enhancer of Stem Cells

PURPOSE

Current human umbilical cord blood stem cell therapy faces the great challenges, because the stem cells are scarce and cannot survive for a long time. Here we describe how hetrombopag, an orally-active TPO receptor agonists, enhanced ex vivo expansion of human UCB stem cells, and protected cardiac myocytes from the damage caused by oxidative stress.

METHODS

Ex vivo expansion of stem cells were performed in serum-free medium supplemented with rhSCF and rhFL plus hetrombopag for 7 days. The percentage and number of stem cell subsets were determined by flow cytometry. Rat cardiac myocytes, ex vivo expanded stem cells, or cardiac myocytes plus ex vivo expanded stem cells were serum starved for 24 hours, and were then subjected to H₂O₂, hetrombopag or both for 12 hours at the indicated concentrations. Cell viability assays, protein microarrays and western blots were then performed in each group.

RESULTS

Our studies first revealed that the combination of hetrombopag and rhTPO manifested additive effect on ex vivo expansion of human UCB stem cells. Besides, hetrombopag dose-dependently enhanced the beneficial effects of ex vivo expanded human UCB MNCs in increasing the survival of injured cardiomyocytes during free oxygen radical stress.

CONCLUSION

These data, for the first time, uncovered a novel function of non-peptide small molecular TPO receptor agonists as enhancers of stem cells in protecting cardiac myocyte survival from oxidative stress damage, which might provide a new therapeutic avenue for the treatment of oxidative stress-related cardiovascular disease. Graphical abstract ᅟ.

CAR-T Cell Therapies From the Transfusion Medicine Perspective

The use of chimeric antigen receptor (CAR)-T cell therapy for the treatment of hematologic malignancies has generated significant excitement over the last several years. From a transfusion medicine perspective, the implementation of CAR-T therapy as a potential mainstay treatment for not only hematologic but also solid-organ malignancies represents a significant opportunity for growth and expansion. In this review, we will describe the rationale for the development of genetically redirected T cells as a cancer therapeutic, the different elements that are required to engineer these cells, as well as an overview of the process by which patient cells are harvested and processed to create and subsequently validate CAR-T cells. Finally, we will briefly describe some of the toxicities and clinical efficacy of CAR-T cells in the setting of patients with advanced malignancy.

Insight on stem cell preconditioning and instructive biomaterials to enhance cell adhesion, retention, and engraftment for tissue repair

Stem cells are a promising solution for the treatment of a variety of diseases. However, the limited survival and engraftment of transplanted cells due to a hostile ischemic environment is a bottleneck for effective utilization and commercialization. Within this environment, the majority of transplanted cells undergo apoptosis prior to participating in lineage differentiation and cellular integration. Therefore, in order to maximize the clinical utility of stem/progenitor cells, strategies must be employed to increase their adhesion, retention, and engraftment in vivo. Here, we reviewed key strategies that are being adopted to enhance the survival, retention, and engraftment of transplanted stem cells through the manipulation of both the stem cells and the surrounding environment. We describe how preconditioning of cells or cell manipulations strategies can enhance stem cell survival and engraftment after transplantation. We also discuss how biomaterials can enhance the function of stem cells for effective tissue regeneration. Biomaterials can incorporate or mimic extracellular function (ECM) function and enhance survival or differentiation of transplanted cells in vivo. Biomaterials can also promote angiogenesis, enhance engraftment and differentiation, and accelerate electromechanical integration of transplanted stem cells. Insight gained from this review may direct the development of future investigations and clinical trials.

Stem cell treatment for acute myocardial infarction

BACKGROUND

Cell transplantation offers a potential therapeutic approach to the repair and regeneration of damaged vascular and cardiac tissue after acute myocardial infarction (AMI). This has resulted in multiple randomised controlled trials (RCTs) across the world.

OBJECTIVES

To determine the safety and efficacy of autologous adult bone marrow stem cells as a treatment for acute myocardial infarction (AMI), focusing on clinical outcomes.

SEARCH METHODS

This Cochrane review is an update of a previous version (published in 2012). We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 2), MEDLINE (1950 to March 2015), EMBASE (1974 to March 2015), CINAHL (1982 to March 2015) and the Transfusion Evidence Library (1980 to March 2015). In addition, we searched several international and ongoing trial databases in March 2015 and handsearched relevant conference proceedings to January 2011.

SELECTION CRITERIA

RCTs comparing autologous bone marrow-derived cells with no cells in patients diagnosed with AMI were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references, assessed the risk of bias of the included trials and extracted data. We conducted meta-analyses using random-effects models throughout. We analysed outcomes at short-term (less than 12 months) and long-term (12 months or more) follow-up. Dichotomous outcomes are reported as risk ratio (RR) and continuous outcomes are reported as mean difference (MD) or standardised MD (SMD). We performed sensitivity analyses to evaluate the results in the context of the risk of selection, performance and attrition bias. Exploratory subgroup analysis investigated the effects of baseline cardiac function (left ventricular ejection fraction, LVEF) and cell dose, type and timing of administration, as well as the use of heparin in the final cell solution.

MAIN RESULTS

Forty-one RCTs with a total of 2732 participants (1564 cell therapy, 1168 controls) were eligible for inclusion. Cell treatment was not associated with any changes in the risk of all-cause mortality (34/538 versus 32/458; RR 0.93, 95% CI 0.58 to 1.50; 996 participants; 14 studies; moderate quality evidence), cardiovascular mortality (23/277 versus 18/250; RR 1.04, 95% CI 0.54 to 1.99; 527 participants; nine studies; moderate quality evidence) or a composite measure of mortality, reinfarction and re-hospitalisation for heart failure (24/262 versus 33/235; RR 0.63, 95% CI 0.36 to 1.10; 497 participants; six studies; moderate quality evidence) at long-term follow-up. Statistical heterogeneity was low (I(2) = 0% to 12%). Serious periprocedural adverse events were rare and were generally unlikely to be related to cell therapy. Additionally, cell therapy had no effect on morbidity, quality of life/performance or LVEF measured by magnetic resonance imaging. Meta-analyses of LVEF measured by echocardiography, single photon emission computed tomography and left ventricular angiography showed evidence of differences in mean LVEF between treatment groups although the mean differences ranged between 2% and 5%, which are accepted not to be clinically relevant. Results were robust to the risk of selection, performance and attrition bias from individual studies.

AUTHORS' CONCLUSIONS

The results of this review suggest that there is insufficient evidence for a beneficial effect of cell therapy for AMI patients. However, most of the evidence comes from small trials that showed no difference in clinically relevant outcomes. Further adequately powered trials are needed and until then the efficacy of this intervention remains unproven.

The Clinical Status of Stem Cell Therapy for Ischemic Cardiomyopathy

Ischemic cardiomyopathy (ICM) is becoming a leading cause of morbidity and mortality in the whole world. Stem cell-based therapy is emerging as a promising option for treatment of ICM. Several stem cell types including cardiac-derived stem cells (CSCs), bone marrow-derived stem cells, mesenchymal stem cells (MSCs), skeletal myoblasts (SMs), and CD34(+) and CD 133(+) stem cells have been applied in clinical researches. The clinical effect produced by stem cell administration in ICM mainly depends on the transdifferentiation and paracrine effect. One important issue is that low survival and residential rate of transferred stem cells in the infracted myocardium blocks the effective advances in cardiac improvement. Many other factors associated with the efficacy of cell replacement therapy for ICM mainly including the route of delivery, the type and number of stem cell infusion, the timing of injection, patient's physical condition, the particular microenvironment onto which the cells are delivered, and clinical condition remain to be addressed. Here we provide an overview of the pros and cons of these transferred cells and discuss the current state of their therapeutic potential. We believe that stem cell translation will be an ideal option for patients following ischemic heart disease in the future.

Cardiac tissue engineering and regeneration using cell-based therapy

Stem cell therapy and tissue engineering represent a forefront of current research in the treatment of heart disease. With these technologies, advancements are being made into therapies for acute ischemic myocardial injury and chronic, otherwise nonreversible, myocardial failure. The current clinical management of cardiac ischemia deals with reestablishing perfusion to the heart but not dealing with the irreversible damage caused by the occlusion or stenosis of the supplying vessels. The applications of these new technologies are not yet fully established as part of the management of cardiac diseases but will become so in the near future. The discussion presented here reviews some of the pioneering works at this new frontier. Key results of allogeneic and autologous stem cell trials are presented, including the use of embryonic, bone marrow-derived, adipose-derived, and resident cardiac stem cells.

Cell-based therapy by implanted human bone marrow-derived mononuclear cells improved bone healing of large bone defects in rats

QUESTION/AIM: Cell-based therapy by cultivated stem cells (mesenchymal stem cells [MSC] and endothelial progenitor cells [EPC]) in a large-sized bone defect has already shown improved vascularization and new bone formation. However, these methods are clinically afflicted with disadvantages. Another heterogeneous bone marrow cell population, the so-called human bone marrow-derived mononuclear cells (BMC), has nevertheless been used clinically and showed improved vascularization in ischemic limbs or in the myocardium. For clinical use, a certified process has been established; thus, BMC were isolated from bone marrow aspirate by density gradient centrifugation, washed, cleaned, and given back to patients within several hours. This investigation tested the ability of human BMC seeded on beta-tricalcium phosphate (β-TCP) and placed into a large bone defect in rats to improve the bone healing process in vivo.

METHODS

Human EPC were isolated from buffy coat, and MSC or BMC, respectively, were isolated from bone marrow aspirate by density gradient centrifugation. 1.0×10(6) cells were loaded onto 750 μL β-TCP (0.7-1.4 mm). Large femoral defects (6 mm) in athymic rats were created surgically and stabilized with an internal fixateur. The remaining defects were filled with β-TCP granules alone (group 1), β-TCP+EPC/MSC (group 2), or β-TCP+BMC (group 3). After 8 weeks, histomorphometric analysis (new bone formation), radiological microcomputer tomography analysis (bony bridging), and biomechanical testing (three-point bending) were achieved. Moreover, a tumorigenicity study was performed to evaluate the safety of BMC implantation after 26 weeks. For statistical analysis, the Kruskal-Wallis test was used.

RESULTS

Eight weeks after implantation of EPC/MSC or BMC, respectively, we detected a more significant new bone formation compared to control. In group 2 and 3, bony bridging of the defect was seen. In the control group, more chondrocytes and osteoid were detected. In the BMC and EPC/MSC group, respectively, less chondrocytes and a significantly more advanced bone formation were observed. The biomechanical stability of the bone regenerate was significantly enhanced if BMC and EPC/MSC, respectively, were implanted compared to control. Moreover, no tumor formation was detected either macroscopically or histologically after 26 weeks of BMC implantation.

DISCUSSION

Implanted BMC suggest that a heterogeneous cell population may provide a powerful cellular therapeutic strategy for bone healing in a large bone defect in humans.

An update on stem cell therapies for acute coronary syndrome

Well into the second decade since its conception, cell transplantation continues to undergo intensive evaluation for the treatment of myocardial infarction. At a mechanistic level, its objectives remain to replace lost cardiac cell mass with new functioning cardiomyocytes and vascular cells, thereby minimizing infarct size and scar formation, and improving clinical outcomes by preventing adverse left ventricular remodeling and recurrent ischemic events. Many different cell types, including pluripotent stem cells and various adult-derived progenitor cells, have been shown to have therapeutic potential in preclinical studies, while early phase human trial experience has provided divergent outcomes and fundamental lessons, emphasizing that there remain key issues to address and challenges to overcome before cell therapy can be applied to wider clinical practice. The purpose of this review is to provide a balanced update on recent seminal developments in this exciting field and look to the next important steps to ensure its forward progression.

Characterization of bone marrow mononuclear cells on biomaterials for bone tissue engineering in vitro

Bone marrow mononuclear cells (BMCs) are suitable for bone tissue engineering. Comparative data regarding the needs of BMC for the adhesion on biomaterials and biocompatibility to various biomaterials are lacking to a large extent. Therefore, we evaluated whether a surface coating would enhance BMC adhesion and analyze the biocompatibility of three different kinds of biomaterials. BMCs were purified from human bone marrow aspirate samples. Beta tricalcium phosphate (β-TCP, without coating or coated with fibronectin or human plasma), demineralized bone matrix (DBM), and bovine cancellous bone (BS) were assessed. Seeding efficacy on β-TCP was 95% regardless of the surface coating. BMC demonstrated a significantly increased initial adhesion on DBM and β-TCP compared to BS. On day 14, metabolic activity was significantly increased in BMC seeded on DBM in comparison to BMC seeded on BS. Likewise increased VEGF-synthesis was observed on day 2 in BMC seeded on DBM when compared to BMC seeded on BS. The seeding efficacy of BMC on uncoated biomaterials is generally high although there are differences between these biomaterials. Beta-TCP and DBM were similar and both superior to BS, suggesting either as suitable materials for spatial restriction of BMC used for regenerative medicine purposes in vivo.

Three-dimensional culture and characterization of mononuclear cells from human bone marrow

BACKGROUND AIMS

The diverse phenotypic changes and clinical and economic disadvantages associated with the monolayer expansion of bone marrow-derived mesenchymal stromal cells (MSCs) have focused attention on the development of one-step intraoperative cells therapies and homing strategies. The mononuclear cell fraction of bone marrow, inclusive of discrete stem cell populations, is not well characterized, and we currently lack suitable cell culture systems in which to culture and investigate the behavior of these cells.

METHODS

Human bone marrow-derived mononuclear cells were cultured within fibrin for 2 weeks with or without fibroblast growth factor-2 supplementation. DNA content and cell viability of enzymatically retrieved cells were determined at days 7 and 14. Cell surface marker profiling and cell cycle analysis were performed by means of multi-color flow cytometry and a 5-ethynyl-2'-deoxyuridine incorporation assay, respectively.

RESULTS

Total mononuclear cell fractions, isolated from whole human bone marrow, was successfully cultured in fibrin gels for up to 14 days under static conditions. Discrete niche cell populations including MSCs, pericytes and hematopoietic stem cells were maintained in relative quiescence for 7 days in proportions similar to that in freshly isolated cells. Colony-forming unit efficiency of enzymatically retrieved MSCs was significantly higher at day 14 compared to day 0; and in accordance with previously published works, it was fibroblast growth factor-2-dependant.

CONCLUSIONS

Fibrin gels provide a simple, novel system in which to culture and study the complete fraction of bone marrow-derived mononuclear cells and may support the development of improved bone marrow cell-based therapies.

Myeloid-derived growth factor (C19orf10) mediates cardiac repair following myocardial infarction

Paracrine-acting proteins are emerging as a central mechanism by which bone marrow cell-based therapies improve tissue repair and heart function after myocardial infarction (MI). We carried out a bioinformatic secretome analysis in bone marrow cells from patients with acute MI to identify novel secreted proteins with therapeutic potential. Functional screens revealed a secreted protein encoded by an open reading frame on chromosome 19 (C19orf10) that promotes cardiac myocyte survival and angiogenesis. We show that bone marrow-derived monocytes and macrophages produce this protein endogenously to protect and repair the heart after MI, and we named it myeloid-derived growth factor (MYDGF). Whereas Mydgf-deficient mice develop larger infarct scars and more severe contractile dysfunction compared to wild-type mice, treatment with recombinant Mydgf reduces scar size and contractile dysfunction after MI. This study is the first to assign a biological function to MYDGF, and it may serve as a prototypical example for the development of protein-based therapies for ischemic tissue repair.

Effect of repetitive intra-arterial infusion of bone marrow mononuclear cells in patients with no-option limb ischemia: the randomized, double-blind, placebo-controlled Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial

BACKGROUND

Patients with severe limb ischemia may not be eligible for conventional therapeutic interventions. Pioneering clinical trials suggest that bone marrow-derived cell therapy enhances neovascularization, improves tissue perfusion, and prevents amputation. The objective of this trial was to determine whether repetitive intra-arterial infusion of bone marrow mononuclear cells (BMMNCs) in patients with severe, nonrevascularizable limb ischemia can prevent major amputation.

METHODS AND RESULTS

The Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial is a randomized, double-blind, placebo-controlled clinical trial in 160 patients with severe, nonrevascularizable limb ischemia. Patients were randomly assigned to repetitive (3 times; 3-week interval) intra-arterial infusion of BMMNC or placebo. No significant differences were observed for the primary outcome, ie, major amputation at 6 months, with major amputation rates of 19% in the BMMNC versus 13% in the placebo group (relative risk, 1.46; 95% confidence interval, 0.62-3.42). The safety outcome (all-cause mortality, occurrence of malignancy, or hospitalization due to infection) was not significantly different between the groups (relative risk, 1.46; 95% confidence interval, 0.63-3.38), neither was all-cause mortality at 6 months with 5% versus 6% (relative risk, 0.78; 95% confidence interval, 0.22-2.80). Secondary outcomes quality of life, rest pain, ankle-brachial index, and transcutaneous oxygen pressure improved during follow-up, but there were no significant differences between the groups.

CONCLUSIONS

Repetitive intra-arterial infusion of autologous BMMNCs into the common femoral artery did not reduce major amputation rates in patients with severe, nonrevascularizable limb ischemia in comparison with placebo. The general improvement in secondary outcomes during follow-up in both the BMMNC and the placebo group, as well, underlines the essential role for placebo-controlled design of future trials.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00371371.

Comparative study of different centrifugation protocols for a density gradient separation media in isolation of osteoprogenitors from bone marrow aspirate

INTRODUCTION

Human bone marrow contains osteoprogenitors capable of differentiating into osteoblasts. Density gradient centrifugation (DGC) is a commonly used method to isolate osteoprogenitors from bone marrow. Numerous studies used different dilution and centrifugation protocols, which might affect cell yields and quality. Moreover, the relative isolation efficiencies of the different separation protocols have not been investigated. This study compares the enrichment efficacy of the two different centrifugation protocols for a commonly used DGC media in isolation of osteoprogenitors.

MATERIAL AND METHOD

Bone marrow was aspirated from human anterior iliac crests. Osteoprogenitors are isolated with Ficoll DGC media. A centrifugal force of 400 g and 1:1 dilution was compared with the centrifugal force of 1000 g after three dilution times with a buffer.

RESULTS

The average numbers of isolated cells were significantly higher when using lower centrifugal force with 1:1 dilution, however, there was no detectable difference between Colony-forming unit-fibroblast (CFU-F) forming capacity, STRO-1 positivity, osteogenic differentiation or mineralization abilities between protocols.

CONCLUSION

Both protocols could isolate competent and functional osteoprogenitors, while a lower centrifugal force (400 g) with 1:1 dilution produced recovery of more osteoprogenitors.

Stem cell therapy for heart failure

The last decade has witnessed the publication of a large number of clinical trials, primarily using bone marrow-derived stem cells as the injected cell. Much has been learned through these "first-generation" clinical trials. The considerable advances in our understanding include (1) cell therapy is safe, (2) cell therapy has been modestly effective, (3) the recognition that in humans bone marrow-derived stem cells do not transdifferentiate into cardiomyocytes or new blood vessels (or at least in sufficient numbers to have any effect). The primary mechanism of action for cell therapy is now believed to be through paracrine effects that include the release of cytokines, chemokines, and growth factors that inhibit apoptosis and fibrosis, enhance contractility, and activate endogenous regenerative mechanisms through endogenous circulating or site-specific stem cells. The new direction for clinical trials includes the use of stem cells capable of cardiac lineage, such as endogenous cardiac stem cells.

Difference in mobilization of progenitor cells after myocardial infarction in smoking versus non-smoking patients: insights from the BONAMI trial

Introduction

Although autologous bone marrow cell (BMC) therapy has emerged as a promising treatment for acute myocardial infarction (AMI), trials reported mixed results. In the BONAMI trial, active smoking reduced cardiac function recovery after reperfused AMI. Therefore, we hypothesized that variability in the functionality of BMCs retrieved from patients with cardiovascular risk factors may partly explain these mixed results. We investigated the characteristics of progenitor cells in active smokers and non-smokers with AMI and their potential impact on BMC therapy efficacy.

Methods

Bone marrow and blood samples from 54 smoking and 47 non-smoking patients enrolled in the BONAMI cell therapy trial were analyzed.

Results

The white BMC and CD45dimCD34+ cell numbers were higher in active smokers (P = 0.001, P = 0.03, respectively). In marked contrast, either bone marrow or blood endothelial progenitor CD45dimCD34 + KDR + cells (EPCs) were decreased in active smokers (P = 0.005, P = 0.04, respectively). Importantly, a multivariate analysis including cardiovascular risk factors confirmed the association between active smoking and lower EPC number in bone marrow (P = 0.04) and blood (P = 0.04). Furthermore, baseline circulating EPC count predicted infarct size decrease at three months post-AMI in non-smokers (P = 0.01) but not in active smokers. Interestingly, baseline circulating EPCs were no longer predictive of cardiac function improvement in the BMC therapy group.

Conclusions

These data suggest that circulating EPCs play an important role in cardiac repair post-AMI only in non-smokers and that active smoking-associated EPC alterations may participate in the impairment of cardiac function recovery observed in smokers after AMI, an effect that was overridden by BMC therapy.

Bone marrow-derived cells for cardiovascular cell therapy: an optimized GMP method based on low-density gradient improves cell purity and function

Background

Cardiovascular cell therapy represents a promising field, with several approaches currently being tested. The advanced therapy medicinal product (ATMP) for the ongoing METHOD clinical study (“Bone marrow derived cell therapy in the stable phase of chronic ischemic heart disease”) consists of fresh mononuclear cells (MNC) isolated from autologous bone marrow (BM) through density gradient centrifugation on standard Ficoll-Paque. Cells are tested for safety (sterility, endotoxin), identity/potency (cell count, CD45/CD34/CD133, viability) and purity (contaminant granulocytes and platelets).

The aims of the present work were (1) to optimize the cell manufacturing process in order to reduce contaminants and (2) to implement additional assays in order to improve product characterization and evaluate product stability.

Methods

BM-MNC were isolated by density gradient centrifugation on Ficoll-Paque. The following process parameters were optimized throughout the study: gradient medium density; gradient centrifugation speed and duration; washing conditions.

Differential cell count was performed by an automated hematology cell analyzer. Immunophenotype and cell viability were determined by flow cytometry. Functional hematopoietic and mesenchymal precursors and cells with angiogenic potential were assessed by colony-forming assays, cell invasion capacity by a fluorimetric assay. Sterility was tested using an automated microbial detection system, endotoxin by a kinetic chromogenic Limulus amebocyte lysate test. T-test was used for statistical analysis.

Results

A new manufacturing method was set up, based on gradient centrifugation on low density Ficoll-Paque, followed by 2 washing steps, of which the second one at low speed. It led to significantly higher removal of contaminant granulocytes and platelets, improving product purity; the frequencies of CD34⁺ cells, CD133⁺ cells and functional hematopoietic and mesenchymal precursors were significantly increased.

The process was successfully validated according to Good Manufacturing Practices.

The resulting ATMP mainly consisted of viable MNC including CD34⁺ and CD133⁺ cell subsets (2.98% ± 1.90% and 0.83% ± 1.32%, respectively), CD184/CXCR4⁺ cells (34% ± 15%), CD34⁺/CD133⁺/CD309⁺ endothelial precursors (44 ± 21 in 10⁶ total cells), cells with invasion capacity, functional hematopoietic and mesenchymal precursors, cells with angiogenic potential; it was stable for 20 hours at 10°C.

Conclusions

The methodological optimization described here resulted in a significant improvement of ATMP quality, a crucial issue to clinical applications in cardiovascular cell therapy.

Stem cells for cardiac repair: problems and possibilities

Ischemic heart disease is a major cause of death throughout the world. In order to limit myocardial damage and possibly generate new myocardium, stem cells are currently being injected into patients with ischemic heart disease. Three major patient investigations, The LateTIME, the TIME and the Swiss Myocardial Infarction trials, have recently addressed the questions of whether progenitor cells from unfractionated bone marrow mononuclear cells limit myocardial damage and what the optimal time to inject these cells after acute myocardial infarctions (AMIs) is. In each of these trials, there were no significant differences between treated and control patients when bone marrow cells were administered 5-7 days or 2-3 weeks after AMIs. Nevertheless, these investigations provide important information regarding clinical trial designs. Patients with AMIs in these trials were treated with percutaneous coronary intervention within a median of 4-5 h after the onset of chest pain. Thereafter, all patients received guideline-guided optimal medical therapy. Consequently, the sizes of AMIs were significantly limited. In patients with small AMIs and near-normal left ventricular ejection fractions, progenitor cells are least effective. However, these trials do question whether autologous bone marrow mononuclear cells are the optimal cells for myocardial repair owing to low numbers of progenitor cells in bone marrow aspirates and the significant variability in potency and efficacy of these cells in patients with chronic multisystem diseases. In contrast, the SCIPIO and the CAUDUCEUS trials examined cardiac progenitor cells in patients with ischemic cardiomyopathies. These trials reported over 1-2 years that cardiac progenitor cells produced significant improvements in left ventricular contractility due to 12-24 g decreases in myocardial scars and 18-23 g increases in viable myocardial muscle. However, caution must be exercised in the interpretation of these studies due to the small numbers of highly selected patients and intra- and inter-observer variability in infarct size measurements. Anatomical and histological examinations of large numbers of patients treated with these cells are necessary to confirm significant generation of myocytes and decreases in infarct size and fibrosis.

Bone marrow mononuclear cell therapy for acute myocardial infarction: a perspective from the cardiovascular cell therapy research network

To understand the role of bone marrow mononuclear cells in the treatment of acute myocardial infarction, this overview offers a retrospective examination of strengths and limitations of 3 contemporaneous trials with attention to critical design features and provides an analysis of the combined data set and implications for future directions in cell therapy for acute myocardial infarction.

Bone marrow mononuclear cell therapy for acute myocardial infarction: a perspective from the cardiovascular cell therapy research network

To understand the role of bone marrow mononuclear cells in the treatment of acute myocardial infarction, this overview offers a retrospective examination of strengths and limitations of 3 contemporaneous trials with attention to critical design features and provides an analysis of the combined data set and implications for future directions in cell therapy for acute myocardial infarction.