Vascular Wall Engineering Via Femtosecond Laser Ablation: Scaffolds with Self-Containing Smooth Muscle Cell Populations

Abstract

For tissue-engineered vascular grafts to reach their full potential, three-dimensional (3D) cellular micro-integration will be necessary. In this study, we utilize femtosecond laser ablation to produce microchannels inside electrospun polycaprolactone (PCL) scaffolds. These microchannels potentially provide spatially controlled cell distributions approaching those observed in vivo. The ability of such laser-ablated microchannels to direct cell seeding was evaluated. The dimensions chosen were 100 μm wide, 100 μm deep and 10 mm long. Femtosecond laser ablation successfully produced these microchannels in the scaffolds without substantially altering the ~900 nm diameter fibers. Flow within these microchannels was studied by injecting fluorescent polystyrene bead solutions. Direct measurement of bead motion yielded an inlet velocity of 2.78 cm s(-1). This was used for modeling two-dimensional (2D) flow using computational fluid dynamics to estimate flow profiles within the microchannel. Successful demonstrations of bead flow were followed by seeding of 500,000 human coronary artery smooth muscle cells (HCASMCs) in proliferative medium at a rate of ~500 μL min(-1). Confocal microscopy and scanning electron microscopy confirmed that the HCASMCs were seeded down the full 10-mm length of the microchannel and stayed within its boundaries. Both nuclei and F-actin were observed within the seeded cells. The presence of F-actin filaments shows that the cells were adhered strongly to the scaffold and remained viable throughout the culture. The concept of "vascular wall engineering" producing intricate cell seeding through microchannels produced via femtosecond laser ablation was validated.

Glioma-astrocyte interactions on white matter tract-mimetic aligned electrospun nanofibers

“…Together, these results show that GBM migration in the presence of astrocytes is a complex process with both pro-and inhibitory cues, and additional mechanisms beyond the scope of this study likely also contribute. For example, a previous study showed a decrease in glioma migration when astrocyteglioma gap junctions were inhibited, 13 suggesting that interactions between the two cell types positively influence migration of glioma cells, similar to our experimental observations. In both the GFAP and migration studies, it should be noted that the chemical fixation methods employed and the use of proteolytic agents for cell removal may influence results.…”

“…8,10 Previous work investigating GBMastrocyte interactions has demonstrated that astrocytes upregulate expression of GFAP and matrix metalloproteinase-2 (MMP-2) in the presence of GBM cells 11,12 and has also shown that astrocytes play a supportive role in GBM migration. 13 Thus, in these investigations, we evaluated the relationship between these two well-established characteristics of normal astrocytes and GBM cells, respectively: GFAP expression and cell migration. In addition, previously reported experiments primarily relied on two dimensional (2D) tissue culture polystyrene substrates that fail to capture unique topographical features of the tumor microenvironment, particularly the blood vessel and white matter tracts along which GBMs migrate.…”

Rapid response oxygen-sensing nanofibers

“…After cooling to room temperature, the uniformly mixed solution was electrospun according to procedures used previously. [18, 19] The large diameter PCL fibers were fabricated by using dichloromethane (DCM) as the solvent. The typical sample thickness (approximately 100 μm) for sensing applications was held constant by fixing the deposition time at 400 seconds.…”

Microfabricated Porous Silk Scaffolds for Vascularizing Engineered Tissues

“…Furthermore, many synthetic material systems lack a porous bulk matrix surrounding the microchannels, which significantly limits utility in engineering tissues around the microchannels. Efforts have been reported to build porous micropatterned synthetic material systems, however the pores were small in diameter and cell infiltration into the bulk space was not demonstrated 9, 13…”