Controlled Exposure of Bioactive Growth Factor in 3D Amyloid Hydrogel for Stem Cells Differentiation

Abstract

promoting regeneration. [3] Hydrogels present a unique microstructure to the encapsulated cells influencing cell signaling and hence cellular fate. Peptide hydrogels are a class of physical hydrogels where the component peptides self-assemble noncovalently to form an ordered nanostructure [4] and eventually supramolecular networks, which entrap water for gelation. [5] Recently with the advent of protein engineering, relatively simple peptide based hydrogels have gained increasing attention in biomaterial development. [6] The major advantage of employing short peptides as hydrogelators is that their properties could be easily tuned and controlled via side chain modification and chemical alteration to achieve the desired functionality. [7] Moreover, peptide hydrogels are also advantageous as they have less potential for inflammation and also have biodegradable components [8] compared to polymer based hydrogels. Recently, we have shown the application of another class of hydrogels based on "amyloid fibrils" for possible application in 2D, 3D cell culture, and stem cell differentiation. [2a,b] Amyloids are highly stable protein/peptide aggregates with cross-β-sheet rich structure. [9] Although amyloids are historically associated with various human diseases, recent discoveries have suggested functional roles of amyloids that help organisms survival rather causing diseases. [10] Also, studies have shown that amyloid fibrils are rather benign or less toxic species compared to soluble oligomers. [11] Due to higher order structure, amyloid possesses unique stability against various harsh environmental conditions such as wide ranges of pHs, temperature, and proteases, which makes amyloids attractive for designing biomaterials for tissue engineering as well as various nanotechnological applications. [2h,12] Recently, a number of studies also indicate that amyloids are unique cell adhesive material that promotes adhesion of cells without the presence of tripeptide motif Arg-Gly-Asp (RGD) motif. [13] Our recent study has also shown that amyloid based hydrogels could be suitably used as implantable materials for tissue engineering, owing to their noninflammatory property along with ease of delivery with minimally invasive surgery. [2b] In a natural tissue environment, extra cellular matrix (ECM) has a favorable nanotopography [14] for cells and contains large depots of growth factors that affect the physiological functions of the cells. [3c] In an attempt to mimic such a natural niche to provide better stem cell differentiation, presence and controlled exposure of various growth factors are Amyloid based hydrogels can mimic the extracellular matrix and serve as matrices for tissue engineering both in vitro and in vivo. A pH responsive selfassembled amyloid hydrogel system is used to encapsulate various growth factors for driving stem cell differentiation toward neuronal lineage. Diffusion studies with fluorescence recovery after photobleaching and bulk release with the model protein fluorescein isothiocyanate-bovin...

Amyloid fibril-based hydrogels for high-throughput tumor spheroid modeling

“…The rheological data including stress-strain rheology measurement showed that all these hydrogels are soft and thixotropic (Supplementary Fig. 3c and d) as shown previously for many amyloid hydrogels 16,[21][22][23][24]31 . The FTIR data of dried hydrogel fibrils showed cross-β-sheet rich structure ( Supplementary Fig.…”

“…Amyloids also exhibit native functions in host organisms such as matrix formation in melanosome biogenesis 17 and storage of hormones in secretory granules 18 . Irrespective of primary sequence, amyloid fibrils of many proteins/peptides also showed robust cell adhesion and hydrogels composed of amyloid fibrils can promote stem cell differentiation to neurons 16,[19][20][21][22][23][24] . Many advantages that distinguish amyloid hydrogels from other peptides/protein-based hydrogels, include i) cross-β structure of amyloid network possessing a unique combination of hydrophobic and hydrophilic surfaces, with an ability to bind to various small molecules and biomolecules with a high affinity [25][26][27][28] ii) they are highly stable and resistant to extreme conditions, such as pH, temperature and proteases 29,30 .…”

Modeling Endothelialized Hepatic Tumor Microtissues for Drug Screening

“…Increased secretion of Alb might have contributed to the aggregation of PLGA architectures due to the viscous and glial properties of Alb. [26] Similarly, the levels of MRP were also augmented, which participates in the regulation of redistributing intracellular constituents to protect the cells. [26] It is believed that the adherence of individual architectures and aggregation of multicellularladen PLGA PMs could to a good extent represent the vascularized tumor microtissues in vitro.…”

The study of establishment of an in vivo tumor model by three-dimensional cells culture systems methods and evaluation of antitumor effect of biotin-conjugated pullulan acetate nanoparticles

“…7,8 With the support of natural or synthetic polymers which were safety and stability, 3D innovative culture systems were developed to enhance the adhesion, proliferation and increase the release of secreted factors by cultured cells. [9][10][11] Hydrogels are a 3D network made of natural or synthetic polymers crosslinked that can entrap large volume of water or biological fluid. [12][13][14] In recent years, hydrogels have been employed to generate three-dimensional (3D) models that better mimic the specific native microenvironment compared to 2D cell cultures.…”