The Presence of Apoptotic Bone Marrow Cells Impairs the Efficacy of Cardiac Cell Therapy

A Safe and Convenient Method to Isolate Bone Marrow Mononuclear Cells in Clinical Practice

BACKGROUND

Bone marrow mononuclear cells (BMMNCs) are becoming a promising cell therapy in regeneration medicine. BMMNCs are now obtained by density gradient centrifugation (DGC) in clinical practice, which is complicated and greatly influenced by human manipulation.

OBJECTIVE

Our objective is to develop a simple and safe method to isolate BMMNCs.

METHODS

Bone marrow was aspirated from nine minipigs. The optimal hypotonic sodium chloride (NaCl) concentration was first investigated based on the BMMNCs viability and lysis efficiency tests. Afterward, three different methods (ammonium chloride (NH4Cl) lysis, hypotonic NaCl lysis, and DGC) were used for BMMNCs isolation. Nucleated cell yield, residual red blood cells (RBCs) level, BMMNCs viability, apoptotic cell percentage, and colony-forming ability were measured in three groups. Cell morphology, cell phenotype, proliferative capacity, and osteogenic, adipogenic, and chondrogenic lineage differentiation potential of the bone marrow mesenchymal stem cells (BMSCs) were compared in three groups.

RESULTS

0.3% NaCl lysis group had optimal cell viability and lysis efficiency and the 0.3% NaCl lysis group had higher cell yield and lower RBCs remaining in BMMNCs compared to the DGC group. The BMSCs harvested from the NH4Cl lysis group had the worst proliferation ability. The NaCl lysis group was not inferior to the other two groups in terms of other biological characteristics of BMMNCs/BMSCs.

CONCLUSIONS

The optimal concentration for hypotonic NaCl lysis to obtain BMMNCs is 0.3%. Compared with NH4Cl lysis and DGC, the 0.3% NaCl lysis may be a safe, appropriate, and low-cost method for BMMNCs isolation.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

E7-Modified Substrates to Promote Adhesion and Maintain Stemness of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have drawn great attention in clinical applications due to the self-renewal ability, multi-differentiation potential, and low immunogenicity. However, there are challenges in the ex vivo expansion of MSCs, including low efficiency, stemness loss, and safety. Therefore, it is crucial to construct a substrate that can show an alterable affinity to MSCs, and induce efficient cell expansion with minimal stemness loss. In this study, EPLQLKM (E7)-modified substrates with tunable E7 densities are fabricated on PEGylated substrates. The PEG layer with an average thickness of 1.7 nm shows good antifouling ability. E7-modified substrates have an improving effect on adhesion and spreading of the rat bone marrow-derived mesenchymal stem cells (rBMSCs), along with the increase of E7 densities. rBMSCs on E7-modified substrates maintain the stem cell phenotypes, and shows robust proliferation and multilineage differentiation, especially on the substrates with high E7 densities. In summary, this study provides a novel strategy of E7 functionalization to promote adhesion and maintain stemness of MSCs, which holds great potentials in the functionalization of microcarriers for the expansion of MSCs.

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.

Density gradient centrifugation compromises bone marrow mononuclear cell yield

Bone marrow mononuclear cells (BMNCs) are widely used in regenerative medicine, but recent data suggests that the isolation of BMNCs by commonly used Ficoll-Paque density gradient centrifugation (DGC) causes significant cell loss and influences graft function. The objective of this study was to determine in an animal study whether and how Ficoll-Paque DGC affects the yield and composition of BMNCs compared to alternative isolation methods such as adjusted Percoll DGC or immunomagnetic separation of polymorphonuclear cells (PMNs). Each isolation procedure was confounded by a significant loss of BMNCs that was maximal after Ficoll-Paque DGC, moderate after adjusted Percoll DGC and least after immunomagnetic PMN depletion (25.6±5.8%, 51.5±2.3 and 72.3±6.7% recovery of total BMNCs in lysed bone marrow). Interestingly, proportions of BMNC subpopulations resembled those of lysed bone marrow indicating symmetric BMNC loss independent from the isolation protocol. Hematopoietic stem cell (HSC) content, determined by colony-forming units for granulocytes-macrophages (CFU-GM), was significantly reduced after Ficoll-Paque DGC compared to Percoll DGC and immunomagnetic PMN depletion. Finally, in a proof-of-concept study, we successfully applied the protocol for BMNC isolation by immunodepletion to fresh human bone marrow aspirates. Our findings indicate that the common method to isolate BMNCs in both preclinical and clinical research can be considerably improved by replacing Ficoll-Paque DGC with adapted Percoll DGC, or particularly by immunodepletion of PMNs.

Stem cells and regenerative medicine - future perspectives

Stem cell research has expanded at an exponential rate, but its therapeutic applications have progressed much more slowly. Currently, the research focuses on understanding embryonic, adult, and inducible pluripotent stem cells. Translation of adult stem cell research has established a definitive benefit that is greater than that of the current standard of care in the field of cardiovascular medicine. The future of stem cell research and therapy will continue to provide novel avenues of diagnostics, therapeutics, and tissue regeneration. Here we discuss a brief history of stem cell research as it transitioned from the 20th to the 21st century. We address lessons learned in the first decade of the new millennium that could help guide others to translate research into therapy across disciplines. Finally, we highlight future goals and challenges that must be overcome and offer some perspective on the bright future of stem cell research and therapy.

Cellular plasticity: the good, the bad, and the ugly? Microenvironmental influences on progenitor cell therapy

Progenitor cell based therapies have emerged for the treatment of ischemic cardiovascular diseases where there is insufficient endogenous repair. However, clinical success has been limited, which challenges the original premise that transplanted progenitor cells would orchestrate repair. In this review, we discuss the basics of endothelial progenitor cell therapy and describe how microenvironmental changes (i.e., trophic and mechano-structural factors) in the damaged myocardium influence progenitor cell plasticity and hamper beneficial therapeutic outcome. Further understanding of these microenvironmental clues will enable optimization of cell therapy at all levels. We discuss current concepts and provide future perspectives for the enhancement of progenitor cell therapy, and merge these advances into a combined approach for ischemic tissue repair.