BM-derived cell therapies for cardiovascular disease

Early endothelial progenitor cells in bone marrow are a biomarker of cell therapy success in patients with critical limb ischemia

BACKGROUND AIMS

Endothelial progenitor cells (EPC) have been proposed for autologous angiogenic therapy. The objectives of this study were to quantify EPC in the peripheral blood and bone marrow mononuclear cells (BM-MNC) of patients with critical limb ischemia that had received BM-MNC as a cell therapy product, and to study the putative relationship between the presence of EPC and the process of neovascularization in toe or transmetatarsal amputation specimens.

METHODS

Early and late endothelial progenitor cells (CFU-EC and ECFC) were cultivated and quantified according to published methods in peripheral blood and BM-MNC from patients with critical limb ischemia (CLI; n = 11) enrolled in the OPTIPEC trial ( http://clinicaltrials.gov/ct2/show/NCT00377897 ) to receive BM-MNC as a cell therapy product.

RESULTS

Eight out of the 11 patients had undergone amputations. Three of the patients displayed a neoangiogenic process that was associated with a higher number of CFU-EC in BM-MNC, while CD3+ , CFU-GM and CD34+ in BM-MNC, and EPC in peripheral blood, did not correlate with the appearance of newly formed vessels. As expected, circulating CFU-EC and ECFC counts were significantly lower in CLI patients compared with age-matched controls.

CONCLUSIONS

In patients with critical limb ischemia, EPC in peripheral blood were decreased compared with healthy individuals. However, in BM-MNC we found that relative numbers of CFU-EC could be used as an indicator to discriminate patients with neoangiogenic processes. These results need to be confirmed in a randomized study.

Mesenchymal stem cells in hematopoietic stem cell transplantation

Mesenchymal stromal/stem cells (MSC) of bone marrow (BM) origin not only provide the supportive microenvironmental niche for hematopoietic stem cells (HSC) but are capable of differentiating into various cell types of mesenchymal origin, such as bone, fat and cartilage. In vitro and in vivo data suggest that MSC have low inherent immunogenicity, modulate/suppress immunologic responses through interactions with immune cells, and home to damaged tissues to participate in regeneration processes through their diverse biologic properties. MSC derived from BM are being evaluated for a wide range of clinical applications, including disorders as diverse as myocardial infarction and newly diagnosed diabetes mellitus type 1. However, their use in HSC transplantation, either for enhancement of hematopoietic engraftment or for treatment/prevention of graft-versus-host disease, is far ahead of other indications. Ease of isolation and ex vivo expansion of MSC, combined with their intriguing immunomodulatory properties and their impressive record of safety in a wide variety of clinical trials, make these cells promising candidates for further investigation.

Age and stress related phenotypical changes in bone marrow CD34+ cells

OBJECTIVE

Phenotypical changes in the human bone marrow (BM) due to age and stress have not so far been properly addressed in the literature. In the present study, we compared CD34(+) BM cells between older and young volunteers. The influence of stress on CD34(+) cell phenotype in older patients was investigated in an age-matched group with acute myocardial infarction (AMI). Cytokines thought to influence BM CD34(+) cell homeostasis were also analysed.

MATERIAL AND METHODS

BM mononuclear cells of 10 older volunteers and of 7 young volunteers (18-25 years), as well as 22 AMI patients, were analysed by flow cytometry for the following markers: CD34, CD38, CD117 (c-kit) and CD133. Blood samples were analysed for CRP, IL-6, MCP-1, IL-8, MMP-9, TIMP-1 and TNFalpha by ELISA methods.

RESULTS

Significantly higher numbers of CD34(+) CD38(-) cells (both absolute and relative) were observed in older volunteers than in young volunteers and AMI patients. Higher numbers of immature progenitors, namely CD34(+)CD38(-) cells and CD34(+)CD38(-)CD117(+)CD133(+) cells, were observed among older volunteers compared to the other groups. However, the relative number of CD34(+) cells lacking CD38 expression or expressing CD133 was higher in the old volunteers and AMI patients. None of the circulating factors investigated correlated with any of the cell population yields.

CONCLUSION

In this study, we found that the absolute and relative numbers of BM CD34(+)CD38(-) progenitor cells increase with age. The increment is attenuated in patients with AMI.

Role of mesenchymal stromal cells in solid organ transplantation

Mesenchymal stromal cells (MSCs) originally isolated from bone marrow have been derived from almost every tissue in the body. These multipotent cells can be differentiated in vitro and in vivo into various cell types of mesenchymal origin, such as bone, fat, and cartilage. Furthermore, under some experimental conditions, these cells can differentiate into a wider variety of cell types. Upon systemic administration, ex vivo expanded MSCs preferentially home to damaged tissues and participate in regeneration processes through their diverse biological properties. In vitro and in vivo data suggest that MSCs have low inherent immunogenicity and modulate/suppress immunologic responses through interactions with different immune cells. Ease of isolation and ex vivo expansion of MSCs, combined with their intriguing differentiation and immunomodulatory potential, and their impressive record of safety in clinical trials make these cells prime candidates for cellular therapy. Mesenchymal stromal cells derived from bone marrow are currently being evaluated for a wide range of clinical applications including for treatment of immune dysregulation disorders such as acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. In the future, MSCs might potentially provide novel therapeutic options for treatment/prevention of rejection and/or repair of organ allografts through their multifaceted properties.