Research paper
Enhanced survival of transplanted human adipose-derived stem cells by co-delivery with liposomal apoptosome inhibitor in fibrin gel matrix

https://doi.org/10.1016/j.ejpb.2013.05.014Get rights and content

Abstract

To improve the survival of transplanted human adipose-derived stem cells (ADSCs), a liposome preparation containing the apoptosome inhibitor, NS3694, was formulated and co-delivered with ADSCs in fibrin gel scaffolds. Liposomes provided enhanced effect on ADSC proliferation in vitro as compared to free drug. Exposure of ADSCs to liposomal NS3694 for 7 days did not affect the surface marker expression profile. NS3694 encapsulated in negatively charged liposomes composed of phosphatidylcholine, phosphatidylglycerol, and cholesterol was evaluated in vivo following subcutaneous transplantation in mice. Survival of ADSCs co-delivered with liposomal NS3694 was significantly higher than that of untreated ADSCs or ADSCs treated with free NS3694 or empty liposomes. An immunohistochemical analysis revealed a higher number of human nucleus-positive cells after treatment with liposomal NS3694 than following treatment with free NS3694. Similarly, liposomal NS3694 significantly enhanced survival of transplanted ADSCs in rabbits compared to other treatments. Taken together, our results indicate the potential of liposomal NS3694 co-delivered with ADSCs using fibrin gel systems as an in vivo-survival enhancer.

Introduction

Human adipose-derived stem cells (ADSCs) have been studied for future applications in regenerative medicine [1], [2]. ADSCs represent an abundant autologous source of adult stem cells and can be harvested in a relatively non-invasive manner through liposuction [3]. Thanks to these unique advantages compared to other adult stem cells, there has been a dramatic increase in preclinical studies using ADSCs [4]. ADSC-based cell therapy is currently undergoing clinical trials for the treatment of several diseases, including Crohn’s disease [5], acute myocardial infarction [6], [7], and facial lipoatrophy [8], and more ADSC-based cell therapeutic candidates are expected to enter clinical trials in the near future [9], [10].

Although substantial progress has been made in the therapeutic applications of ADSCs, overcoming the low survival rates of stem cells after in vivo transplantation remains a major challenge. A previous study reported that the actual survival rate of mesenchymal stem cells after transplantations was less than 5% in mice [11], [12]. Increasing the survival rate of transplanted ADSCs may be crucial for improving the therapeutic outcomes of ADSC-based cell therapies.

Despite the importance of survival of transplanted stem cells, studies of survival-enhancing strategies are limited. In such studies, it was reported that survival of mesenchymal stem cells after transplantation is enhanced by stromal-derived factor 1α treatment [13] and lipopolysaccharide preconditioning [14]. However, additional progress is still required to achieve more significant increases in the survival of ADSCs.

In this study, we tested whether the survival of ADSCs could be improved by co-delivery with liposomal formulations of the apoptosome inhibitor, NS3694 [15], in a fibrin gel matrix. The underlying concept is that sustained release and retention within the microenvironment of ADSCs should help maximize the function of the encapsulated bioactive component. Although NS3694 has been reported to enhance the survival of tumor cells, its effects on ADSCs have not been tested. Here, we report the effects of liposomal NS3694 on the survival of transplanted ADSCs in mice and rabbits.

Section snippets

Culture of human primary ADSCs

Human ADSCs were isolated from adipose tissues of women (age, 35–55 years) undergoing liposuction. All patients provided informed consent, and the institutional review board of Asan Hospital (Seoul, Korea) approved the use of the clinical samples for this research. ADSCs were prepared and seeded in 150-mm culture dishes (SPL Life Sciences, Gyeonggi-do, Korea) at a density of 1 × 106 cells/dish. Cells were maintained in Dulbecco’s modified Eagle medium (DMEM; Welgene, Daegu, Korea) supplemented with

Effect of free NS on the survival of ADSCs

The reported working mechanism of NS3694 [17] is depicted in Fig. 1A. In this previous study using the human cervical carcinoma HeLa cell line, NS3694 was shown to bind to cytochrome c, inhibiting the formation of apoptosomes. As shown in Fig. 1B, treatment of ADSCs with free NS for 24 h significantly enhanced cell survival in a concentration-dependent manner, producing a maximal increase in cell viability at 50 μM. DMSO was used to solubilize free NS. In Fig. 1B, the control group was not

Discussion

In this study, we demonstrated that NS3694 in liposomes enhanced the survival of ADSCs in vitro and in vivo. Our results emphasize the importance of liposomal formulations for the in vivo efficacy of NS3694 in enhancing the survival of transplanted ADSCs.

NS3694 was encapsulated in liposomes to improve its solubility and prolong its release under in vivo conditions. For treatment of cells in vitro, free NS was solubilized in DMSO. However, it is not possible to administer free NS3694 in DMSO

Acknowledgments

This work was supported by research grants from the Ministry of Science, ICT and Future Planning (2012K001398; 2013035166), and from the Bio & Medical Technology Development Program of the National Research Foundation funded by the Korean government (MSIP) (No. 2013036131).

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    These authors contributed equally to this work.

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