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Background:: Various cell culture platforms that could display native environmental cue-mimicking stimuli were developed, and effects of environmental cues on cell behaviors were studied with the cell culture platforms. Likewise, various cell culture platforms mimicking native trabecular meshwork (TM) composed of juxtacanalicular, corneoscleral and uveal meshwork located in internal scleral sulcus were used to study effects of environmental cues and/or drug treatments on TM cells and glaucoma development. Glaucoma is a disease that could cause blindness, and cause of glaucoma is not clearly identified yet. It appears that aqueous humor (AH) outflow resistance increased by damages on pathway of AH outflow can elevate intraocular pressure (IOP). These overall possibly contribute to development of glaucoma. Methods:: For the study of glaucoma, static and dynamic cell culture platforms were developed. Particularly, the dynamic platforms exploiting AH outflow-mimicking perfusion or increased IOP-mimicking increased pressure were used to study how perfusion or increased pressure could affect TM cells. Overall, potential mechanisms of glaucoma development, TM structures and compositions, TM cell culture platform types and researches on TM cells and glaucoma development with the platforms were described in this review. Results and conclusion:: This will be useful to improve researches on TM cells and develop enhanced therapies targeting glaucoma.

Tissue fibrosis is a leading cause of mortality and is characterized by excessive protein deposition and altered tissue mechanical properties. In pathological fibrosis, as well as cancer related fibrosis, tissue pericytes and fibroblasts transition from a quiescent to a myofibroblastic phenotype. In vitro models are needed to better understand how these cells are influenced by their local microenvironment. Here, we developed a fibrous network platform to mimic the structure of the extracellular matrix, where fibers consist of cross-linked hyaluronic acid hydrogels with controlled cross-link density and mechanical properties. As a model myofibroblast precursor, primary hepatic stellate cells were seeded onto fibers with either low (soft) or high (stiff) cross-link density, either directly after isolation (quiescent) or following preculture on tissue culture plates (activated). In general, both quiescent and activated cells showed an increase in spreading, alpha smooth muscle actin expression, and the formation of multicellular clusters on soft fibers when compared to stiff fibers. Further, inhibition of alpha smooth muscle actin decreased activation of cells on soft fibers. This is likely due to fiber recruitment in soft fibers that increased local fiber density, whereas stiff fibers resisted recruitment. This work emphasizes the importance of substrate topography on cell–material interactions and shows that tunable fibrous hydrogels are a relevant culture platform for studying fibrosis and mechanotransduction in disease.

Cellular dynamics under complex topographical microenvironments are important for many biological processes in development and diseases, but systematic investigation has been limited due to the lack of technology. Herein, we developed a new dynamic cell patterning method based on a cell-friendly photoresist polymer that allows in situ control of cell dynamics on nanostructured surfaces. Using this method, we quantitatively compared the spreading dynamics of cells on nanostructured surfaces to those on flat surfaces. Furthermore, we investigated how cells behaved when they simultaneously encountered two topographically distinct surfaces during spreading. This method will allow many exciting opportunities in the fundamental study of cellular dynamics.

Cholesterol 7α-hydroxylase (CYP7A1) plays a critical role in regulation of bile acid synthesis in the liver. CYP7A1 mRNAs have very short half-lives, and bile acids destabilize CYP7A1 mRNA via the 3'-untranslated region (3'-UTR). However, the underlying mechanism of translational regulation of CYP7A1 mRNA remains unknown. Screening of a human micro RNA (miRNA) microarray has identified five differentially expressed miRNAs in human primary hepatocytes treated with chenodeoxycholic acid, GW4064, or fibroblast growth factor (FGF)19. These compounds also significantly induced the expression of miR-122a, a liver-specific and the predominant miRNA in human hepatocytes. The putative recognition sequences for miR-122a and miR-422a were localized in the 3'-UTR of human CYP7A1 mRNA. The miR-122a and miR-422a mimics inhibited, whereas their inhibitors stimulated CYP7A1 mRNA expression. These miRNAs specifically inhibited the activity of the CYP7A1-3'-UTR reporter plasmids, and mutations of miRNA binding sites in 3'-UTR abrogated miRNA inhibition of reporter activity. These results suggest that miR-122a and miR-422a may destabilize CYP7A1 mRNA to inhibit CYP7A1 expression. However, these miRNAs did not play a role in mediating FGF19 inhibition of CYP7A1 transcription. Under certain conditions, miRNA may reduce CYP7A1 mRNA stability to inhibit bile acid synthesis, and the miR-122a antagomirs may stimulate bile acid synthesis to reduce serum cholesterol and triglycerides.

Cholesterol 7α-hydroxylase (CYP7A1) plays a critical role in regulation of bile acid synthesis in the liver. CYP7A1 mRNAs have very short half-lives, and bile acids destabilize CYP7A1 mRNA via the 3′-untranslated region (3′-UTR). However, the underlying mechanism of translational regulation of CYP7A1 mRNA remains unknown. Screening of a human micro RNA (miRNA) microarray has identified five differentially expressed miRNAs in human primary hepatocytes treated with chenodeoxycholic acid, GW4064, or fibroblast growth factor (FGF)19. These compounds also significantly induced the expression of miR-122a, a liver-specific and the predominant miRNA in human hepatocytes. The putative recognition sequences for miR-122a and miR-422a were localized in the 3′-UTR of human CYP7A1 mRNA. The miR-122a and miR-422a mimics inhibited, whereas their inhibitors stimulated CYP7A1 mRNA expression. These miRNAs specifically inhibited the activity of the CYP7A1-3′-UTR reporter plasmids, and mutations of miRNA binding sites in 3′-UTR abrogated miRNA inhibition of reporter activity. These results suggest that miR-122a and miR-422a may destabilize CYP7A1 mRNA to inhibit CYP7A1expression. However, these miRNAs did not play a role in mediating FGF19 inhibition of CYP7A1transcription. Under certain conditions, miRNA may reduce CYP7A1 mRNA stability to inhibit bile acid synthesis, and the miR-122a antagomirs may stimulate bile acid synthesis to reduce serum cholesterol and triglycerides.

Mechanical cues induce a variety of downstream effects on cells, including the regulation of stem cell behavior. Cell fate is typically characterized on biomaterial substrates where mechanical and chemical properties can be precisely tuned; however, most of these substrates do not recapitulate the biological complexity of the extracellular matrix (ECM). Here, hydrogels are engineered for mechanobiological studies using two major components of the ECM: hyaluronic acid (HA) and fibronectin (FN). Rather than typical surface chemisorption of FN to substrates, the system contains full‐length FN covalently crosslinked to HA throughout the hydrogel. The control over the mechanical properties of the hydrogel independent of the concentration of FN and the ability to culture viable cells either on top or encapsulated within the hydrogels are shown. Interestingly, human mesenchymal stem cells (MSCs) experience an increase in nuclear translocation of the yes‐associated protein (YAP) to the nucleus when cultured on (2D) substrates with increasing amounts of FN while maintaining constant hydrogel stiffness. However, this FN dependence on nuclear YAP translocation is not observed for MSCs encapsulated in (3D) hydrogels. This work develops complex hydrogels that recapitulate features of the ECM for the control of stem cells in both 2D and 3D environments. Extracellular matrix‐like environments are engineered via combination of hyaluronic acid and FN with controlled mechanical properties for stem cell engineering and mechanobiological studies.

Fibrous scaffolds fabricated via electrospinning are being explored to repair injuries within dense connective tissues. However, there is still much to be understood regarding the appropriate scaffold properties that best support tissue repair. In this study, the influence of the stiffness of electrospun fibers on cell invasion into fibrous scaffolds is investigated. Specifically, soft and stiff electrospun fibrous networks are fabricated from crosslinked methacrylated hyaluronic acid (MeHA), where the stiffness is altered via the extent of MeHA crosslinking. Meniscal fibrochondrocyte (MFC) adhesion and migration into fibrous networks are investigated, where the softer MeHA fibrous networks are easily deformed and densified through cellular tractions and the stiffer MeHA fibrous networks support ≈50% greater MFC invasion over weeks when placed adjacent to meniscal tissue. When the scaffolds are sandwiched between meniscal tissues and implanted subcutaneously, the stiffer MeHA fibrous networks again support enhanced cellular invasion and greater collagen deposition after 4 weeks when compared to the softer MeHA fibrous networks. These results indicate that the mechanics and deformability of fibrous networks likely alter cellular interactions and invasion, providing an important design parameter toward the engineering of scaffolds for tissue repair. Electrospun fibrous hydrogels are being developed for meniscal tissue repair. To better understand the influence of scaffold biophysical properties on cellular invasion, fiber stiffness is varied. Softer networks are easily deformed by cells to densify fibers, whereas stiffer networks support increased cell invasion both by seeded cells and when placed adjacent to meniscus tissue.