In situ-forming, cell-instructive hydrogels based on glycosaminoglycans with varied sulfation patterns.

Glycosaminoglycan (GAG)-based hydrogels were proven highly effective to direct cell fate decisions by modulating the administration of cytokines. The sulfation pattern of the GAG component critically controls its affinity to proteins and thus governs the release of cytokines from GAG-containing gel systems. To apply this principle in the design of in situ assembling materials suitable for cell embedding and injection into tissues, we developed a platform of bio-orthogonally crosslinked star-shaped poly(ethylene glycol) (starPEG)-GAG hydrogels that display variable GAG sulfation patterns. Combining rational design for tuning the hydrogel network properties and a reaction-diffusion model for predicting transport processes within the matrices, we exemplarily applied the resulting materials for tailoring morphogenic and chemotactic gradients of platelet-derived growth factor-BB (PDGF-BB) in 3D. Conditions identified with this approach were demonstrated to effectively control the fate and morphogenesis of embedded mesenchymal stem cells (MSCs). Adjusting the sulfation patterns of glycosamnioglycans used in the preparation of in situ forming hydrogels is thus concluded to create new powerful options for modulating biomolecular signals in cell fate control, paving the way for advanced 3D cultures and precision tissue engineering.

In vitro characterization of a liposomal formulation of celecoxib containing 1,2-distearoyl-sn-glycero-3-phosphocholine, cholesterol, and polyethylene glycol and its functional effects against colorectal cancer cell lines.

Nanosized liposomal drug delivery systems are well suited for selective drug delivery at tumor sites. Celecoxib (CLX) is a highly hydrophobic cyclooxygenase-2 inhibitor that can reduce the incidence of colorectal polyps; however, the adverse cardiovascular effects limit its applicability. Here, we report a liposomal formulation of CLX using 1,2-Distearoyl-sn-glycero-3-phosphocholine, cholesterol, and polyethylene glycol. Encapsulation efficiency of the drug was greater than 70%; the release was slow and sustained with only 12%-20% of CLX released in the first 12 h. Flow cytometry and confocal microscopy studies using the colon cancer cell lines HCT-116 and SW620 showed significantly higher cellular association and internalization of the liposomes after incubation for 6 h when compared with 30 min. The liposomes did not colocalize with transferrin, but had a punctuate appearance, indicating vesicular localization. Cell proliferation was inhibited by 95% and 78%, respectively, in SW620 and HT29 cells after incubation with 600 µM liposomal CLX for 72 h. Moreover, cellular motility, as shown by a scratch wound healing assay, was also significantly (p = 0.006) inhibited when SW620 cells were incubated with 400 µM liposomal CLX. This is the first report of the successful encapsulation of CLX in a long-circulating liposomal formulation that could be effective against colorectal cancer.