Effect of hydrogel porosity on marrow stromal cell phenotypic expression

Abstract

This study describes investigation of porous photocrosslinked oligo[(polyethylene glycol) fumarate] (OPF) hydrogels as potential matrix for osteoblastic differentiation of marrow stromal cells (MSCs). The porosity and interconnectivity of porous hydrogels were assessed using magnetic resonance microscopy (MRM) as a noninvasive investigative tool that could image the water construct inside the hydrogels at a high-spatial resolution. MSCs were cultured onto the porous hydrogels and cell number was assessed using PicoGreen DNA assay. Our results showed 10% of cells initially attached to the surface of scaffolds. However, cells did not show significant proliferation over a time period of 14 days. MSCs cultured on porous hydrogels had increased alkaline phosphatase activity as well as deposition of calcium, suggesting successful differentiation and maturation to the osteoblastic phenotype. Moreover, continued expression of type I collagen and osteonectin over 14 days confirmed osteoblastic differentiation of MSCs. MRM was also applied to monitor osteogenesis of MSCs on porous hydrogels. MRM images showed porous scaffolds became consolidated with osteogenic progression of cell differentiation. These findings indicate that porous OPF scaffolds enhanced MSC differentiation leading to development of bone-like mineralized tissue.

Structured Macroporous Hydrogels: Progress, Challenges, and Opportunities

“…The salt is subsequently leached from the matrix (typically using water or weak bases), creating micro/macropores within the hydrogel matching the size of the salt crystal template. Sodium chloride salt crystals are most commonly used to prepare porous hydrogel scaffolds given their availability and bioinertness; [40,41] for example, porous photocrosslinked oligo (polyethylene glycol) fumarate (OPF) hydrogels have been fabricated with tunable pore sizes ranging from 100 to 500 µm using NaCl templates. [41] Other salts can also be applied, with CaCO 3 attracting particular interest given its low solubility at high/neutral pH values but significantly higher solubility in acidic conditions.…”

“…Sodium chloride salt crystals are most commonly used to prepare porous hydrogel scaffolds given their availability and bioinertness; [40,41] for example, porous photocrosslinked oligo (polyethylene glycol) fumarate (OPF) hydrogels have been fabricated with tunable pore sizes ranging from 100 to 500 µm using NaCl templates. [41] Other salts can also be applied, with CaCO 3 attracting particular interest given its low solubility at high/neutral pH values but significantly higher solubility in acidic conditions. [34] On this basis, hydrogels can be formed in aqueous conditions that can maintain the size/structure of the salt porogen without requiring the use of an organic solvent.…”

Sustained Delivery of Dibutyryl Cyclic Adenosine Monophosphate to the Transected Spinal Cord Via Oligo [(Polyethylene Glycol) Fumarate] Hydrogels

“…27,36 After centrifugation, N-vinyl pyrrolidinone (NVP) crosslinker was added. Ninety milligrams of microspheres was added to 1 mL of OPF solution, which was then poured into glass molds and crosslinked using UV light.…”

“…22,23 The molecular weight of the poly(ethylene glycol) used in macromer formation controls the mechanical and degradation properties of the OPF hydrogels. 23,24 Potential applications of these hydrogels include bone tissue engineering, [24][25][26][27] scaffold material for marrow stromal cell attachment and differentiation, [28][29][30][31] cell encapsulation, 30,31 cartilage tissue engineering, 32 and the controlled release of various compounds. [33][34][35] Recent studies suggest applications in the nervous system using positively charged hydrogels.…”

Cell Encapsulating Biomaterial Regulates Mesenchymal Stromal/Stem Cell Differentiation and Macrophage Immunophenotype

“…The differences in calcium mineralization were less striking, however, for the monoculture and coculture gelatin/polyethylene glycol conditions. The enhanced mineralization observed is most likely due to the presence of cell-adhesion sites, the degradability of adjacent gelatin chains, and the overall porosity and stiffness of the gelatin/ polyethylene glycol biomatrix, which suppresses MSC proliferation and promotes cell aggregation, further enhancing MSC differentiation down the osteoblast phenotype [19,[37][38][39][40].…”