Osteogenic behavior of alginate encapsulated bone marrow stromal cells: An in vitro study

Sodium alginate is a useful polymer for the encapsulation and immobilization of a variety of cells in tissue engineering because it is biocompatible, biodegradable and easy to process into injectable microbeads. Despite these properties, little is known of the efficacy of calcium cross-linked alginate gel beads as a biodegradable scaffold for osteogenic cell proliferation and differentiation. In this study, we investigated the ability of rabbit derived bone marrow cells (BMCs) to proliferate and differentiate in alginate microbeads and compared them with BMCs cultured in poly-l-lysine (PLL) coated microbeads and on conventional 2D plastic surfaces. Results show that levels of proliferation and differentiation in microbeads and on tissue culture plastics were comparable. Cell proliferation in microbeads however diminished after fortification with a coating layer of PLL. Maximum cell numbers observed were, 3.32 × 105 ± 1.72 × 103; 3.11 × 105 ± 1.52 × 103 and 3.28 × 10 5 ± 1.21 × 103 for the uncoated, PLL coated and plastic surface groups respectively. Alkaline phosphatase and protein expressions reflected the stage of cell differentiation. We conclude that calcium cross-linked alginate microbeads can act as a scaffold for BMC proliferation and osteogenic differentiation and has potential for use as 3D degradable scaffold. © 2007 Springer Science+Business Media, LLC.link_to_subscribed_fulltex

Potential of glucan HBP-A in chondrocytes-alginate hydrogel constructs

To explore the biological characteristics of an injectable chondrocytes-alginate hydrogel, constructs in the presence of glucan HBP-A as well as its role in cartilage tissue engineering, chondrocytes were isolated from rabbit knee cartilage and verified by immunocytochemistry for type II collagen. The constructs were embedded with HBP-A and then injected to nude mice subcutaneously. Six weeks after transplantaiton, the specimens were collected for Safranin O staining and transmission electron microscopy (TEM). The mRNA expressions of disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTs-5), aggrecan and type II collegan in constructs were determined by real time PCR. Newly generated cartilaginous tissue was found after transplantation, and the collagen was obvious in the HBP-A group. In accordance with morphological observations, the mRNA expression of type II collagen was also increased significantly, accompanied by decreased expression of ADAMTs-5 (P<0.05) in the HBP-A group compared with the control group. © 2011 Academic Journals.link_to_subscribed_fulltex

In vitro evaluation of alginate encapsulated adipose-tissue stromal cells for use as injectable bone graft substitute

This study aims to investigate the survival and osteogenic behavior of murine-derived adipose-tissue stromal cells (ATSCs) encapsulated in alginate microcapsules thereby instigating further studies in this cell delivery strategy for in vivo osteogenesis. Cell viability was quantified using a tetrazolium-based assay and osteogenic differentiation was evaluated by both alkaline-phosphatase (ALP) histochemistry and osteocalcin mRNA analysis. Following microencapsulation, cell numbers increased from 3.9 × 103 on day 1 to 7.8 × 103 on day 7 and maintained excellent viability in the course of 21-day culture. ALP was 6.9, 5.5, and 3.2 times higher than monolayer cultures on days 7, 14, and 21, respectively. In addition, osteocalcin mRNA was detectable in encapsulated cultures earlier (day 14) than monolayer cultures. We conclude that alginate microcapsules can act as three-dimensional matrix for ATSC proliferation and has potential for use as injectable, biodegradable scaffold in bone tissue engineering. © 2006 Elsevier Inc. All rights reserved.link_to_subscribed_fulltex