Fabrication of tapered fluidic microchannels conducive to angiogenic sprouting within GelMA hydrogels.

Abstract Introduction Transplantation of stem cells/tissue constructs into root canal space is a promising strategy for regenerating the lost pulp tissue. However, the root canal system, which is cone-shaped with a taper from the larger coronal end to the smaller apical end, limits the vascular supply and therefore, the regenerative capacity. The current study aimed to fabricate built-in microchannels with different tapers to explore various approaches to endothelialize these microchannels. Methods The fluidic microchannels with varying tapers (parallel, 0.04, 0.06 ) were fabricated within GelMA hydrogel (with or without SCAPs encapsulation) of different concentrations (5%, 7.5%, 10% (w/v)). HUVECs-GFP were seeded alone or with SCAPs in coculture into these microchannels. Angiogenic sprouting was assessed by fluorescence and confocal microscope and ImageJ software. Immunostaining was conducted to illustrate monolayer formation. Data were statistically analyzed by one-way/two-way analysis of variance (ANOVA). Results HUVEC-only inoculation formed an endothelial monolayer inside the microchannel, without angiogenic sprouting. HUVECs-GFP/SCAPs co-cultured at a 1:1 ratio produced the longest sprouting compared with the other three ratios. The average length of the sprouting in 0.04 taper microchannel was significantly longer compared with that in the parallel and 0.06 taper microchannels. Significant differences in HUVECs-GFP sprouting were observed in 5% GelMA hydrogel. Encapsulation of SCAPs within hydrogel further stimulated the sprouting of HUVECs. Conclusions The coculture of SCAPs and HUVECs-GFP at a ratio of 1:1 in 0.04 taper fluidic microchannels fabricated with 5% (w/v) GelMA hydrogel with SCAPs encapsulated was found to be the optimal condition to enhance angiogenesis inside tapered microchannels.