Diffusion of bioactive molecules through the walls of the medial tissue‐engineered hybrid ePTFE grafts for applications in designs of vascular tissue regeneration

Abstract

Strategies of better vascular tissue engineering may require delivery of soluble bioactive signals in cell culture medium to the cells in tissue-regenerating constructs. We measured the diffusivity and permeability of model tissue-engineering bioactive molecules such as water and heparin through the walls of both a hybrid ePTFE graft and a porcine carotid artery, a model vascular tissue. While diffusivities of H(3)-water and H(3)-heparin were measured as 3.9 x 10(-) (6) and 1.6 x 10(-) (6) cm(2)/s in the artery, respectively, under diffusional circulation of cell culture medium through the lumens of the carotid arteries, their corresponding permeabilities were 4.7 x 10(-) (5) and 2.0 x 10(-) (5) cm/s. On the other hand, diffusivities of H(3)-water and H(3)-heparin were also measured as 5.1 x 10(-) (6) and 4.7 x 10(-) (6) cm(2)/s, respectively, in the tissue-engineered hybrid ePTFE grafts; their corresponding permeabilities were 5.1 x 10(-) (5) and 3.7 x 10(-) (5) cm/s. The hybrid graft tissues were engineered by replacing the biodegradable, porous poly(lactide-co-glycolide) layers coated on the ePTFE surfaces with smooth muscle cell-derived tissues for 6 weeks. We analyzed the morphologies of the artery and the engineered hybrid ePTFE tissues with scanning electron microscopy and H&E stains. While the artery had its typical structure properties with layers of intima, media and adventitia, the tissue-engineered ePTFE hybrid graft had two layers of engineered tissues on the inner and outer surfaces of the ePTFE. There were no significant differences among the luminal tissue morphologies of the test samples from the effects of diffusion flow applications, with minor changes on their luminal surfaces. The results of water and heparin diffusion experiments indicated that these bioactive molecules were well transported from the cell culture medium to the tissue-engineering cells, enough to support tissue regeneration. We hope that these transport results may elucidate the transport behaviors of soluble nutrient molecules and biological signals through the vascular constructs under tissue engineering processes.

Interactions of coronary artery smooth muscle cells with 3D porous polyurethane scaffolds

“…Tissue engineering of vascular grafts has emerged as a critical alternative solution to issues of low graft patency rate and supply limitation 29. Both biodegradable and biostable scaffolds have been employed as templates for vascular tissue regeneration 15.…”

“…Tissue engineering of vascular grafts has emerged as a critical alternative solution to issues of low graft patency rate and supply limitation. 29 Both biodegradable and biostable scaffolds have been employed as templates for vascular tissue regeneration. 15 For example, a biodegradable scaffold may be chosen for in vitro tissue engineering since the rates of scaffold degradation and tissue maturation can be controlled in a balanced manner.…”

Semi‐permeable membrane retention of synovial fluid lubricants hyaluronan and proteoglycan 4 for a biomimetic bioreactor

“…The permeability of membranes ± adherent cells to the lubricant i , where i = HA or PRG4, during lubricant transport studies was estimated by obeying Fick’s law, as done in previous studies assessing solute diffusion across a cell-laden membrane (Albelda et al, 1988; Jo et al, 1991; Noh et al, 2006; Sahagun et al, 1990). With sample agitation, the fluid compartments were assumed to be well mixed.…”

“…It has a controlled structure and is resistant to degradation, properties that may facilitate consistent filtration during extended usage. While solute diffusion across ePTFE membranes has been assessed (Noh et al, 2006), no reports have described PRG4 transport across any type of membrane, and transport of HA has been assessed primarily across native synovium (Coleman et al, 2000; Sabaratnam et al, 2004; Scott et al, 2000b). Additionally, ePTFE has been used as a substrate for cell growth, with surface modification to facilitate cell attachment (Bellon et al, 1993; Walluscheck et al, 1996); however, culture and analysis of lubricant-secreting cell types on ePTFE has not previously been described.…”

Evaluation of the Hemodynamics of a Tissue‐engineered Hybrid Graft

“…In our previous in vitro studies, this induced cell adhesion three times greater than that seen on the bare PLGA surface. After induction of cell adhesion, spreading developed well on the surface, and regeneration of new tissues was nearly accomplished by replacing the biodegradable layers of the hybrid scaffold within 6–9 weeks in vitro (1,2).…”