Recent advances in developing in vitro tissue models show that function of hepatocytes is altered in when cultured in 3D configuration and co‐culturing with various non‐parenchymal cells. However, tissue source for such non‐parenchymal cells on viability and metabolic products of hepatocytes have not been explored. In this study, we evaluated the effect of 2D and 3D cultures either with HepaRG cells alone or in combination with liver sinusoidal endothelial cells (LSECs) and human umbilical vein ECs (HUVECs). For 3D cultures, we used chitosan‐gelatin porous structures formed by freeze‐drying. We cultured cells for 8 days before challenging with 1 mm acetaminophen (APAP) and assessed APAP, APAP‐sulfate and APAP‐glucuronide for 24 hours at 6‐hour time intervals using high‐performance liquid chromatography. We used multiple methods (phase contrast, confocal and scanning electron microscopy and histology via hematoxylin and eosin staining) to ensure cell distribution. We also measured total protein content and albumin secretion and viability. HUVEC 3D co‐cultures showed the lowest HepaRG cell viability, while both 2D and 3D LSEC co‐cultures had highest HepaRG cell viability. In addition, 3D cultures had significantly higher EC viability relative to 2D cultures. Further, HUVEC co‐cultures showed reduced total protein content and albumin expression as early as day 4. However, urea production on a total protein content basis did not change. In addition, LSEC 3D co‐cultures had the highest APAP conversion with reduced APAP‐sulfate and APAP‐glucuronide formation. CYP3A4 was higher in co‐culture with HUVEC for 2D and 3D cultures. In conclusion, HepaRG cells with EC co‐cultures demonstrated sensitivity to the EC line used.
Purpose
To investigate in vitro transdermal delivery of tofacitinib citrate across human skin using microporation by microneedles and iontophoresis alone and in combination.
Methods
In vitro permeation studies were conducted using vertical Franz diffusion cells. Microneedles composed of polyvinyl alcohol and carboxymethyl cellulose were fabricated and successfully characterized using scanning electron microscopy. The microchannels created were further characterized using histology, dye binding study, scanning electron microscopy, and confocal microscopy studies. The effect of microporation on delivery of tofacitinib citrate was evaluated alone and in combination with iontophoresis. In addition, the effect of current density on iontophoretic delivery was also investigated.
Results
Total delivery of tofacitinib citrate via passive permeation was found out to be 11.04 ± 1 μg/sq.cm. Microporation with microneedles resulted in significant enhancement where a 28-fold increase in delivery of tofacitinib citrate was observed with a total delivery of 314.7±33.32 μg/sq.cm. The characterization studies confirmed the formation of microchannels in the skin where successful disruption of stratum corneum was observed after applying microneedles. Anodal iontophoresis at 0.1 and 0.5 mA/sq.cm showed a total delivery of 18.56 μg/sq.cm and 62.07 μg/sq.cm, respectively. A combination of microneedle and iontophoresis at 0.5 mA/sq.cm showed the highest total delivery of 566.59 μg/sq.cm demonstrating a synergistic effect. A sharp increase in transdermal flux was observed for a combination of microneedles and iontophoresis.
Conclusion
This study demonstrates the use of microneedles and iontophoresis to deliver a therapeutic dose of tofacitinib citrate via transdermal route.
Abstract:In tissue engineering, porous biodegradable scaffolds are used as templates for regenerating required tissues. With the advances in computational tools, many modeling approaches have been considered. For example, fluid flow through porous medium can be modeled using the Brinkman equation where permeability of the porous medium has to be defined. In this review, we summarize various models recently reported for defining permeability and non-invasive pressure drop monitoring as a tool to validate dynamic changes in permeability. We also summarize some models used for scaffold degradation and integrating mass transport in the simulation.
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