Evaluation of cell-laden polyelectrolyte hydrogels incorporating poly(l-Lysine) for applications in cartilage tissue engineering

Abstract

To address the lack of reliable long-term solutions for cartilage injuries, strategies in tissue engineering are beginning to leverage developmental processes to spur tissue regeneration. This study focuses on the use of poly(L-lysine) (PLL), previously shown to up-regulate mesenchymal condensation during developmental skeletogenesis in vitro, as an early chondrogenic stimulant of mesenchymal stem cells (MSCs). We characterized the effect of PLL incorporation on the swelling and degradation of oligo(poly(ethylene) glycol) fumarate) (OPF)-based hydrogels as functions of PLL molecular weight and dosage. Furthermore, we investigated the effect of PLL incorporation on the chondrogenic gene expression of hydrogel-encapsulated MSCs. The incorporation of PLL resulted in early enhancements of type II collagen and aggrecan gene expression and type II/type I collagen expression ratios when compared to blank controls. The presentation of PLL to MSCs encapsulated in OPF hydrogels also enhanced N-cadherin gene expression under certain culture conditions, suggesting that PLL may induce the expression of condensation markers in synthetic hydrogel systems. In summary, PLL can function as an inductive factor that primes the cellular microenvironment for early chondrogenic gene expression but may require additional biochemical factors for the generation of fully functional chondrocytes.

Spatiotemporal control of growth factors in three-dimensional printed scaffolds

“…(1,10,64–67) Effective growth factor patterning requires an understanding of not only what growth factors are relevant to tissue formation and ingrowth and in what concentrations for each tissue, but also how factors interact to synergistically enhance or inhibit tissue formation. For example, it is well-understood that bone morphogenetic proteins (BMP-2, BMP-3, BMP-7) play a critical role in bone formation and remodeling.…”

“…A variety of previous reports using non-3DP hydrogels have demonstrated that bilayered composites with growth factor gradients can significantly improve cartilage and bone healing and tissue formation. (16,17,27,64,67,72–77) These types of experiments, which created primarily bi- and triphasic constructs with discrete layers, can be considered precursors to the growth factor patterning techniques discussed here, and the incorporation of 3DP techniques to target these tissues is compelling when considering the ability to much more specifically design growth factor gradients. For example, Kundu et al used a multi-head extrusion-based printing system to pattern TGF-β within chondrocyte-encapsulated polycaprolactone/alginate.…”

Tissue Engineering and its Appllication Areas

“…Polimer yüksek basınç altında gaz ile doygun hale gelir ve daha sonra gazın çözeltiden uzaklaşması sağlanır. 23 …”

The fabrication of biomimetic biphasic CAN-PAC hydrogel with a seamless interfacial layer applied in osteochondral defect repair

“…24,25,26 In this study, we have developed a biphasic CAN-PAC hydrogel with a seamless interface that simulated the properties of osteochondral tissue. The bilayer hydrogel was fabricated using a one-pot heat-initiated free radical polymerization method with a density difference between the upper layer and lower layer, as shown in Figure 1.…”