Browsing by Subject "extracellular matrix"

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    Dynamic control of hydrogel crosslinking via sortase-mediated reversible transpeptidation
    (Elsevier, 2018) Arkenberg, Matthew R.; Moore, Dustin M.; Lin, Chien-Chi; Biomedical Engineering, School of Engineering and Technology
    Cell-laden hydrogels whose crosslinking density can be dynamically and reversibly tuned are highly sought-after for studying pathophysiological cellular fate processes, including embryogenesis, fibrosis, and tumorigenesis. Special efforts have focused on controlling network crosslinking in poly(ethylene glycol) (PEG) based hydrogels to evaluate the impact of matrix mechanics on cell proliferation, morphogenesis, and differentiation. In this study, we sought to design dynamic PEG-peptide hydrogels that permit cyclic/reversible stiffening and softening. This was achieved by utilizing reversible enzymatic reactions that afford specificity, biorthogonality, and predictable reaction kinetics. To that end, we prepared PEG-peptide conjugates to enable sortase A (SrtA) induced tunable hydrogel crosslinking independent of macromer contents. Uniquely, these hydrogels can be completely degraded by the same enzymatic reactions and the degradation rate can be tuned from hours to days. We further synthesized SrtA-sensitive peptide linker (i.e., KCLPRTGCK) for crosslinking with 8-arm PEG-norbornene (PEG8NB) via thiol-norbornene photocrosslinking. These hydrogels afford diverse softening paradigms through control of network structures during crosslinking or by adjusting enzymatic parameters during on-demand softening. Importantly, user-controlled hydrogel softening promoted spreading of human mesenchymal stem cells (hMSCs) in 3D. Finally, we designed a bis-cysteine-bearing linear peptide flanked with SrtA substrates at the peptide’s N- and C-termini (i.e., NH2-GGGCKGGGKCLPRTG-CONH2) to enable cyclic/reversible hydrogel stiffening/softening. We show that matrix stiffening and softening play a crucial role in growth and chemoresistance in pancreatic cancer cells. These results represent the first dynamic hydrogel platform that affords cyclic gel stiffening/softening based on reversible enzymatic reactions. More importantly, the chemical motifs that affords such reversible crosslinking were built-in on the linear peptide crosslinker without any post-synthesis modification.
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    High glucose-induced Matrilin-2 expression in mouse mesangial cells was mediated by transforming growth factor beta 1 (TGF-β1)
    (Elsevier, 2016-05) Zhang, Shukun; Zhang, Menglan; Huang, Hong; Zhou, Shiying; Du, Yanshneg; Yi, Xin; Luo, Junming; Department of Health Sciences, School of Health and Rehabilitation Sciences
    This study aimed at evaluating the effect of high glucose on the expression of extracellular matrix (ECM) protein Matrilin-2 and the mechanism underlying this effect by using a mouse mesangial cell line. Mouse mesangial cells (MMCs) were cultured in media containing normal (5 mM d-glucose) or high concentrations of glucose (30 mM d-glucose). The expression of Matrilin-2 was assessed by either RT-PCR or western blot. Additionally, transforming growth factor beta 1 (TGF-β1) inhibitors and TGF-β1 were used to determine whether glucose-regulated Matrilin-2 expression was mediated by the TGF-β1/Smad3 signaling pathway. Our data demonstrated that Matrilin-2 expression was markedly induced by high glucose and TGF-β1. High glucose-induced Matrilin-2 expression was inhibited by TGF-β1/Smad3 inhibitors, indicating that Matrilin-2 was markedly induced by high glucose and this induction was mediated by the TGF-β1/Smad3 pathway. Taken together, our results showed that high-glucose-induced Matrilin-2 expression that was mediated by the TGF-β1/Smad3 signaling pathway might play a role in Diabetic nephropathy (DN) pathogenesis and our finding provided a potential diagnostic and/or therapeutic target for DN.