Transplantation of Cord Blood Mesenchymal Stem Cells as Spheroids Enhances Vascularization

Abstract

Despite promising results from the therapeutic use of stem cells for treating ischemic diseases, the poor survival of cells transplanted into ischemic regions is one of the major problems that undermine the efficacy of stem cell therapy. Cord blood mononuclear cells (CBMNCs) are an alternative source of mesenchymal stem cells (MSCs) without disadvantages, such as the painful and invasive harvesting procedure, of MSCs derived from bone marrow or adipose tissue. In the present study, we investigated whether the angiogenic efficacy of cord blood mesenchymal stem cells (CBMSCs) can be enhanced by grafting as spheroids in a mouse hindlimb ischemia model. Human CBMSC (hCBMSC) spheroids were prepared by using the hanging-drop method. Mouse hindlimb ischemia was induced by excising the femoral artery and its branches. After surgery, the animals were divided into no-treatment, dissociated hCBMSC, and spheroid hCBMSC groups (n=8 per group) and received corresponding hCBMSC treatments. After surgery, the ischemic hindlimbs were monitored for 4 weeks, and then, the ischemic hindlimb muscles were harvested for histological analysis. Apoptotic signaling, angiogenesis-related signal pathways, and blood vessel formation were investigated in vitro and/or in vivo. The transplantation of hCBMSCs as spheroids into mouse ischemic hindlimbs significantly improved the survival of the transplanted cells by suppressing apoptotic signaling while activating antiapoptotic signaling. Furthermore, the transplantation of hCBMSCs as spheroids significantly increased the number of microvessels and smooth muscle α-actin-positive vessels in the ischemic limbs of mice, and attenuated limb loss and necrosis. Human CBMNC can be considered an alternative source of MSC, and spheroid-based hCBMSC delivery can be considered a simple and effective strategy for enhancing the therapeutic efficacy of hCBMSCs.

Mesenchymal Stem Cells: Roles and Relationships in Vascularization

“…For example, in both in vitro and in vivo environments, MSCs transplanted in spheroids produced by a hanging-drop method improved the viability of the MSCs. 100 MSC spheroid transplantation, compared with MSCs from monolayer, resulted in increased microvessel formation and reduced limb loss and necrosis in ischemic mice. While the 3D environment may increase paracrine signaling and function in the MSCs, the spheroids may also have allowed for longer MSC residency in the tissues compared with MSCs transplanted from monolayer.…”

Three-Dimensional Aggregates of Mesenchymal Stem Cells: Cellular Mechanisms, Biological Properties, and Applications

“…12 In addition, improvement of ischemic limb salvage was shown following CB-MSC and A-MSC aggregate transplantation due to the enhanced vascularization compared to dissociated MSCs. 38,148 A-MSC aggregates showed a significant increase in the rate of wound closure compared to single cells due to the significantly elevated ECM secretions (e.g., tenascin C, collagen VI, and fibronectin) and the secreted soluble factors (e.g., HGF, matrix metalloproteinase-2). 79 Prevention of anoikis through the preservation of ECM proteins was proposed as a potential mechanism of the increased survival of A-MSC aggregates.…”

Transplantation of Heterospheroids of Islet Cells and Mesenchymal Stem Cells for Effective Angiogenesis and Antiapoptosis

“…1b). 21 HSs were formed at various cell number ratios of ICs to hMSCs; 10:1, 2:1, and 1:1. Cell suspension solutions were prepared according to the ratio of the different cells (ICs to hMSCs = 10:1, 2:1, and 1:1), but the total cell number concentration was fixed at 2.7 · 10 4 cells per mL for each group.…”