Extracellular Matrix Stability of Primary Mammalian Chondrocytes and Intervertebral Disc Cells Cultured in Alginate-Based Microbead Hydrogels

Abstract

Three-dimensional alginate constructs are widely used as carrier systems for transplantable cells. In the present study, we evaluated the chondrogenic matrix stability of primary rat chondrocytes and intervertebral disc (IVD) cells cultured in three different alginate-based microbead matrices to determine the influence of microenvironment on the cellular and metabolic behaviors of chondrogenic cells confined in alginate microbeads. Cells entrapped in calcium, strontium, or barium ion gelled microbeads were monitored with the live/dead dual fluorescent cell viability assay kit and the 1,9-dimethylmethylene blue (DMB) assay designed to evaluate sulfated glycosaminoglycan (s-GAG) production. Expression of chondrogenic extracellular matrix (ECM) synthesis was further evaluated by semiquantitative RT-PCR of sox9, type II collagen, and aggrecan mRNAs. Results indicate that Ca and Sr alginate maintained significantly higher population of living cells compared to Ba alginate (p < 0.05). Production of s-GAG was similarly higher in Ca and Sr alginate microbead cultures compared to Ba alginate microbeads. Although there was no significant difference between strontium and calcium up to day 14 of culture, Sr alginate showed remarkably improved cellular and metabolic activities on long-term cultures, with chondrocytes expressing as much as 31% and 44% greater s-GAG compared to calcium and barium constructs, respectively, while IVD cells expressed 63% and 74% greater s-GAG compared to calcium and barium constructs, respectively, on day 28. These findings indicate that Sr alginate represent a significant improvement over Ca- and Ba alginate microbeads for the maintenance of chondrogenic phenotype of primary chondrocytes and IVD cells.

The past, present and future in scaffold-based tendon treatments

“…However, direct cell injections have failed to deliver in a consistent manner in humans due to poor cell localisation [218][219][220][221], triggering an extensive investigation into the optimal cell carrier for tendon repair [1]. The ideal carrier system should prevent cell membrane rupture during the injection process; create increased tissue integration through fast in situ self-assembly; facilitate long-term cell survival and functionality maintenance; and allow spatiotemporal release of the cargo [222][223][224][225][226][227][228][229][230][231]. Preclinical data using either collagen [232] or fibrin [233] hydrogels have demonstrated improved mechanical properties, histological scores, tissue integration and restored functionality using TCs and various stem cell populations [234,235], however clinical use of injectable cell/hydrogel systems is still to be realised.…”

The ECM-Cell Interaction of Cartilage Extracellular Matrix on Chondrocytes

“…COMP specifically locates in some cells of the rough endoplasmic reticulum and has toxic effects on chondrocyte precursors, thus hindering the formation of cartilage and bone [53–59]. A certain amount of strontium and COMP can maintain the structural integrity of the cartilage collagen and fibronectin [52, 60]. …”

In vivo bioactivity of rhBMP-2 delivered with novel polyelectrolyte complexation shells assembled on an alginate microbead core template

“…Calcium cross-linked alginate microbeads were prepared by dripping 2% (w/v) sodium alginate solution into 0.2M CaCl 2 as reported previously [26]. The beads were allowed to incubate overnight in CaCl 2 to ensure formation of a stable core template for multilayered polyelectrolyte (PEC) shell deposition.…”