Linear Shear Conditioning Improves Vascular Graft Retention of Adipose-Derived Stem Cells by Upregulation of the α₅β₁ Integrin

Abstract

Use of adult adipose-derived stem cells (ASCs) as endothelial cell substitutes in vascular tissue engineering is attractive because of their availability. However, when seeded onto decellularized vascular scaffolding and exposed to physiological fluid shear force, ASCs are physically separated from the graft lumen. Herein we have investigated methods of increasing initial ASC attachment using luminal precoats and a novel protocol for the gradual introduction of shear stress to optimize ASC retention. Fibronectin coating of the graft lumen increased ASC attachment by nearly sixfold compared with negative controls. Gradual introduction of near physiological fluid shear stress using a novel bioreactor whereby flow rate was increased every second at a rate of 1.5 dynes/cm(2) per day resulted in complete luminal coverage compared with near complete cell loss following conventional daily abrupt increases. An upregulation of the alpha(5)beta(1) integrin was evinced following exposure to shear stress, which accounts for the observed increase in ASC retention on the graft lumen. These results indicated a novel method for seeding, conditioning, and retaining of adult stem cells on a decellularized vein scaffold within a high-shear stress microenvironment.

Endothelial differentiation of diabetic adipose-derived stem cells

“…Our laboratory has extensively studied the use of these cells to create an intimal surface on a natural vascular tissue conduit (decellularized vein graft). We have previously demonstrated that ASC acquire EC characteristics after culture in either endothelial cell growth supplement or in EGM2 [8e10, 26,27]; upregulate EC-specific markers in response to shear force [9]; and remain attached to the luminal surface of a vascular scaffold using flow conditioning to promote retention of the ASC [26]. In the present study, we evaluate the creation of the graft using ASC from DM patients.…”

Endothelial Differentiation of Adipose-Derived Stem Cells from Elderly Patients with Cardiovascular Disease

“…The segments were decellularized by incubation in 0.075% sodium dodecyl sulfate for 15 h, leaving the vascular basement membrane and extracellular matrix intact, as previously described by us. 23 Decellularized vein segments were opened longitudinally and pinned lumen side up within a seeding chamber. Cells were seeded onto the surface of the vascular basement membrane at 4Â10 5 cells=cm 2 and incubated at 378C for up to 24 h. Cell attachment was quantified indirectly by counting the number of residual cells in the seeding medium after gentle washing with PBS.…”

“…The effect of shear force on cell retention after seeding onto a decellularized vein was determined using a bioreactor and flow conditioning system (Lab VIEW; National Instruments) as described by McIlhenny et al [23]. Briefly, the luminal surface of a decellularized human saphenous vein (5 cm in length) was precoated with fibronectin (18 mg=mL; BD Bioscience) for 1 h at 378C with rotation.…”

Mechanisms for osteogenic differentiation of human mesenchymal stem cells induced by fluid shear stress

“…Activated ERK1/2 and PKA can activate transcription factors, such as Runx2 and AP-1, which can promote the transcription of osteogenic differentiation special genes (Kleiveland et al 2008) important in the osteogenic differentiation of hMSCs. FSS can up-regulate the level of α5β1 in human adipose-derived MSCs (McIlhenny et al 2010). Meanwhile, integrin α5β1 has been demonstrated to have an important role in the regulation of MSC osteogenic differentiation in 2D and 3D culture (Martino et al 2009).…”