Direct reprogramming of fibroblasts into endothelial cells capable of angiogenesis and reendothelialization in tissue-engineered vessels

Abstract

The generation of induced pluripotent stem (iPS) cells is an important tool for regenerative medicine. However, the main restriction is the risk of tumor development. In this study we found that during the early stages of somatic cell reprogramming toward a pluripotent state, specific gene expression patterns are altered. Therefore, we developed a method to generate partial-iPS (PiPS) cells by transferring four reprogramming factors (OCT4, SOX2, KLF4, and c-MYC) to human fibroblasts for 4 d. PiPS cells did not form tumors in vivo and clearly displayed the potential to differentiate into endothelial cells (ECs) in response to defined media and culture conditions. To clarify the mechanism of PiPS cell differentiation into ECs, SET translocation (myeloid leukemia-associated) (SET) similar protein (SETSIP) was indentified to be induced during somatic cell reprogramming. Importantly, when PiPS cells were treated with VEGF, SETSIP was translocated to the cell nucleus, directly bound to the VE-cadherin promoter, increasing vascular endothelialcadherin (VE-cadherin) expression levels and EC differentiation. Functionally, PiPS-ECs improved neovascularization and blood flow recovery in a hindlimb ischemic model. Furthermore, PiPS-ECs displayed good attachment, stabilization, patency, and typical vascular structure when seeded on decellularized vessel scaffolds. These findings indicate that reprogramming of fibroblasts into ECs via SETSIP and VEGF has a potential clinical application.shear stress | stem cell therapy | vascular tissue engineering

Generation of functionally competent and durable engineered blood vessels from human induced pluripotent stem cells

“…Moreover, hiPS cell-derived endothelial precursor cells (EPCs) have been shown to alleviate myocardial insufficiency in bovine models (10) and peripheral arterial disease in murine models (9) and to improve recovery of blood flow in hind-limb ischemia murine models (11). Additionally, a recent hiPS derivation of EPCs using partially reprogrammed fibroblasts, demonstrated a quick reprogramming to ECs and the potential application for acute critical limb ischemia (11).…”

“…Additionally, a recent hiPS derivation of EPCs using partially reprogrammed fibroblasts, demonstrated a quick reprogramming to ECs and the potential application for acute critical limb ischemia (11). There are applications in cell therapybased regenerative medicine, where sustained, durable, and functionally competent blood vessels are crucial, such as in longstanding ischemic (17), arterial, diabetic, or nonhealing ulcers.…”

“…The discovery of human induced pluripotent stem (hiPS) cells (3,4) has brought great hope because of their capacity to differentiate into different cell types and great potential for use in tissue engineering and regeneration (5). Several protocols to derive endothelial and perivascular lineages have been reported, with varying efficiencies (6)(7)(8)(9)(10)(11). Disease-specific hiPS cells may serve as an excellent source for modeling human diseases (4,12,13).…”

Generation and Grafting of Tissue-engineered Vessels in a Mouse Model

“…More recently, stem cells from various sources have been exploited for vascular tissue engineering applications. Indeed, a variety of stem cell types including embryonic stem cells 7 , induced pluripotent stem cells (iPSCs) 8,9 , PiPSC 10,11 , bone marrow-derived mononuclear cells 12 , mesenchymal stem cells 13 , endothelial progenitor cells and adult vessel wallderived stem cell antigen-1 (Sca-1)+ stem/progenitor cells 14,15 have all been demonstrated to be capable of differentiation into either functional endothelial or smooth muscle cells in response to defined media and culture conditions. Furthermore, the unlimited self renewal capacity of the stem cells make them better candidates unlike mature endothelial and smooth muscle cells which can only divide for a finite number of times before undergoing growth arrest and senescence.…”

“…To date, the most common materials used for scaffolds in vascular tissue engineering include polymers of polyglycolic acid, polylactic acid, and poly ε-caprolactone . 10,11 . Thereafter, we designed a decellularized vessel for seeding of PiPSC-derived vascular cells to closely mimic the matrix proteins that exists within a native vessel, thus enhancing grafting and survival efficacy.…”