Proliferation and osteogenic differentiation of human bone marrow stromal cells on alginate-gelatine-hydroxyapatite scaffolds with anisotropic pore structure

Abstract

Porous mineralized scaffolds are required for various applications in bone engineering. In particular, tube-like pores with controlled orientation inside the scaffold may support homogeneous cell seeding as well as sufficient nutrient supply and may facilitate blood vessel ingrowth. Scaffolds with parallely orientated tube-like pores were generated by diffusion-controlled ionotropic gelation of alginate. Incorporation of hydroxyapatite (HA) during the gelation process yielded stable scaffolds with an average pore diameter of approximately 90 microm. To evaluate the potential use of alginate-gelatine-HA scaffolds for bone tissue engineering, in vitro tests with human bone marrow stromal cells (hBMSCs) were carried out. We analysed biocompatibility and cell penetration into the capillary pores by microscopic methods. hBMSCs were also cultivated on alginate-gelatine-HA scaffolds for 3 weeks in the presence and absence of osteogenic supplements. We studied proliferation and osteogenic differentiation in terms of total lactate dehydrogenase (LDH) activity, DNA content and alkaline phosphatase (ALP) activity and found a 10-14-fold increase of cell number after 2 weeks of cultivation, as well as an increase of specific ALP activity for osteogenic-induced hBMSCs. Furthermore, the expression of bone-related genes [ALP, bone sialoprotein II (BSPII)] was analysed. We found an increase of ALP as well as BSPII expression for osteogenic-induced hBMSCs on alginate-gelatin-HA scaffolds.

Novel Biomaterials with Parallel Aligned Pore Channels by Directed Ionotropic Gelation of Alginate: Mimicking the Anisotropic Structure of Bone Tissue

“…precipitation of calcium phosphate during the sol-gelprocess ), • HAP powder, i.e. addition of HAP powder to the alginate sol and structuring of this slurry via ionotropic gelation Dittrich et al, 2006;Dittrich et al, 2007;Bernhardt et al, 2009), • Biphasic but monolithic scaffolds for the therapy of osteochondral defects can be produced through deposition of sol layers differing in composition prior to the gelation .…”

“…6) and change the mechanical properties of the composite materials. The high amount of HAP introduced by addition of ceramic powder results in improved strength compared to the synchronously mineralised composites which was evaluated in wet state Bernhardt et al, 2009). All changes in composition of the sol or slurry prior to ionotropic gelation will influence the pore formation (diameter, length, density) during the sol-gel-process (Dittrich et al, 2007).…”

“…In vitro studies of the degradation kinetics should be carried out under conditions as close as possible to those in vivo, i.e. in the incubator at 37°C/5%CO 2 and in cell culture medium (Bernhardt et al, 2009). Also the mechanical stability over time is differently affected by cell culture medium compared to water or PBS (Dittrich et al, 2007).…”

A study of extraction and characterization of alginates obtained from brown macroalgae Sargassum duplicatum and Sargassum crassifolium from Indonesia

“…5,6 Composites of alginate and hydroxyapatite seeded with osteoblast have also been observed for bone tissue engineering. 7,8 Bone tissue engineering may be an advantage, for instance, to increase ridge width due to resorption from tooth loss or for the treatment of edentulous patients if they lack the appropriate bone volume.…”

“…Next, a high porosity and adequate pore size which can seed and grow cells are necessary; to secure mechanical properties of the scaffold appropriate for the cells. 8,18 For this, alginate should be able to gelled and cross-linked through ionic bonding with divalent cations that act as bridges. 19,20 Essential factor to cross-linked alginate was the presence of carboxyl and carbonyl functional groups; 17 besides, the existance of those functional groups are admired as they mimic the part of the protein group in human.…”