Influence of Physical Properties of Biomaterials on Cellular Behavior

Abstract

PurposeIn this study, we evaluated the effect of hydrogel structural properties on proliferation and biosynthesis activity of encapsulated chondrocytes.MethodsHydrogels with varying structural and mechanical properties were prepared by photopolymerizing PEGDA precursors having MWs of 3.4 kDa, 6 kDa, 10 kDa, and 20 kDa and were characterized for their swelling ratio, network structure, morphology, and mechanical properties. The effect of hydrogel structural properties on the cellular activity of encapsulated chondrocytes was studied over four weeks.ResultsVarying the molecular weight of PEGDA precursors exhibited a significant effect on the structural and mechanical properties of the hydrogels. Large mesh size was found to support cell proliferation. However, extracellular matrix (ECM) accumulation varied with the precursor molecular weight. Both PEGDA 6 kDa and 10 kDa hydrogels supported GAG accumulation, while PEGDA 10 kDa and 20KDa hydrogels supported collagen accumulation. Chondrocytes cultured in PEGDA 10 kDa hydrogels expressed a relative increase in collagen type II and aggrecan expression while maintaining low collagen type I expression.ConclusionsIncreasing mesh size of the hydrogels resulted in an increase in cellular proliferation exhibiting the strong correlation between mesh size and cell growth, while mesh size had a differential effect on ECM accumulation and expression of cartilage specific markers.Electronic Supplementary MaterialThe online version of this article (doi:10.1007/s11095-011-0378-9) contains supplementary material, which is available to authorized users.

Hybrid Cross‐Linking Characteristics of Hydrogel Control Stem Cell Fate

“…Although polymer chains are relatively less random in LM-PEG, it cannot influence MSC function in a biomimetic manner which indicates that polymer morphology achieved through physical cross-link is an effective mechanism for polymer chain assembly and for promoting bioactive functionality in MSCs. Cellular aggregation and enhanced chondrogenesis in hydrogel is typically achieved with excessive cell density ($10 6 cell Á mL À1 ); [20,32] in our studies, cellular aggregation in PEG-PU gels were achieved from low cell density ($10 5 cell Á mL À1 ), indicating the role of physical cross-links to mediate aggregation and chondrogenesis. While beyond the scope of this study, other factors, e.g., gel mechanical properties, diffusion of matrix molecules, might have also influenced the chondrogenic differentiation because cross-linking of gels are related to these properties.…”

Mechanical confinement regulates cartilage matrix formation by chondrocytes

“…The elastic moduli of the hydrogels used in these studies ranges from 2 kPa to 100 kPa 12,14,20,21 , which is comparable to the moduli of chondrocyte PCM, ranging from 10 kPa to 75 kPa 29 . Enhanced stiffness in covalently crosslinked PEG based hydrogels, found to exhibit minimal stress relaxation here, restricted production of sGAG and collagens, distribution of cartilage matrix, and proliferation of chondrocytes 20,21 . However, our work revealed that the impact of stiffness was dependent on hydrogel relaxation.…”

“…As previous work has implicated hydrogel stiffness in mediating cartilage matrix formation 20,21,30 , we next examined how altered hydrogel stiffness regulated the effect of relaxation. In hydrogels with an initial elastic modulus of 20 kPa, trends similar to those in 3 kPa gels were observed, with faster relaxation leading to greater areas of type-II collagen and aggrecan deposition as well as higher quantities of secreted collagen and sGAG (Supplementary Fig.…”

A Three-Dimensional Chondrocyte-Macrophage Coculture System to Probe Inflammation in Experimental Osteoarthritis

“…Poly(ethylene glycol) diacrylate (PEGDA)-based hydrogels were used in this study for the establishment of the 3D coculture system, due to their widespread use in cartilage tissue engineering, [34][35][36][37] their easily tunable mechanical properties, 38,39 and their ability to significantly resist cell adhesion even in serum-containing culture environments relative to many biomaterials. 34,40,41 This latter property permits desired cell adhesion to be ''programmed'' into the PEGDA network through conjugation of bioactive moieties.…”