The Roles of Podoplanin-Positive/Podoplanin-Negative Cells from Adipose-Derived Stem Cells in Lymphatic Regeneration.

Abstract

Secondary lymphedema is a refractory disease, for which adipose-derived stem cells have shown some therapeutic potential. However, the mechanism of this action remains poorly understood. The authors identified podoplanin-expressing adipose-derived stem cells, which allowed them to divide adipose-derived stem cells into podoplanin-positive and podoplanin-negative groups that they characterized in vitro. The authors then used a mouse hindlimb model for lymphedema to trace the fate of podoplanin-positive, podoplanin-negative, and unsorted adipose-derived stem cells in vivo. When induced in culture, podoplanin-positive cells were noted to up-regulate the expression of lymphatic endothelial cell markers, including LYVE-1, and assumed a cobblestone morphology. In addition, a substantial increase in lymphangiogenic cytokines was detected in the podoplanin-positive supernatant. The above findings were largely absent from the podoplanin-negative and unsorted groups. In the mouse model, the implanted cells relieved the limb lymphedema by promoting lymphangiogenesis, with the podoplanin-positive group showing the most significant effect. Immunocolocalization further revealed that the podoplanin-positive cells incorporated into lymphatic vessels were positive for LYVE-1. These data demonstrated that actions by means of both paracrine and differentiation pathways were involved in the adipose-derived stem cell-mediated therapeutic effects. The podoplanin-positive cells possessed lymphatic paracrine and differentiation abilities and may represent lymphatic endothelial cell precursor cells. The podoplanin-negative cells, which constitute a considerable proportion of the adipose-derived stem cells, may play an important paracrine role by secreting mesenchymal stem cell-related factors.