Porous PEOT/PBT scaffolds for bone tissue engineering: Preparation, characterization, and in vitro bone marrow cell culturing

Abstract

The preparation, characterization, and in vitro bone marrow cell culturing on porous PEOT/PBT copolymer scaffolds are described. These scaffolds are meant for use in bone tissue engineering. Previous research has shown that PEOT/PBT copolymers showed in vivo degradation, calcification, and bone bonding. Despite this, several of these copolymers do not support bone marrow cell growth in vitro. Surface modification, such as gas-plasma treatment, is needed to improve the in vitro cell attachment. Porous structures were prepared using a freeze-drying and a salt-leaching technique, the latter one resulting in highly porous interconnected structures of large pore size. Gas-plasma treatment with CO(2) generated a surface throughout the entire structure that enabled bone marrow cells to attach. The amount of DNA was determined as a measure for the amount of cells present on the scaffolds. No significant effect of pore size on the amount of DNA present was seen for scaffolds with pore sizes between 250-1000 microm. Light microscopy data showed cells in the center of the scaffolds, more cells were observed in the scaffolds of 425-500 microm and 500-710 microm pore size compared to the ones with 250-425 microm and 710-1000 microm pores.

The effect of pore size on cell adhesion in collagen-GAG scaffolds

“…In PLLA scaffolds, vascular smooth muscle cells preferentially bind to one range of pore sizes (63 -150 µm) while fibroblasts bind to a wider range (38 -150 µm) [12,13]. A number of cell types exhibit preferences to binding in scaffolds with pore sizes considerably larger than the characteristic cell size, often utilizing a characteristic bridging mechanism where adjacent cells act as support structures to assist bridging large pores; examples include fibrovascular tissue ingrowth into PLLA scaffolds, osteoblast adhesion to polylactide-co-glycolide (PLAGA) scaffolds, and rat marrow cells binding to PEOT/PBT scaffolds [7,14,15]. Additionally, the mean pore size of scaffolds has also been shown to significantly influence cell morphology and phenotypic expression [16][17][18].…”

Influence of freezing rate on pore structure in freeze-dried collagen-GAG scaffolds

“…The optimal scaffold pore size that allows maximal entry of cells [2] as well as cell adhesion and matrix deposition has been shown to vary with different cell types [3,4]. Scaffold pore size has been observed to influence adhesion, growth, and phenotype of a wide variety of cell types, notably endothelial cells, vascular smooth muscle cells, fibroblasts, osteoblasts, rat * Manuscript marrow cells, chondrocytes, preadipocytes, and adipocytes [5][6][7][8][9][10][11][12]. Scaffold heterogeneity has been shown to lead to variable cell adhesion and to affect the ability of the cell to produce a uniform distribution of extracellular matrix proteins [5].…”

Tissue Engineering for Tissue and Organ Regeneration

“…Foams and textiles are the two predominant types of scaffolds used in tissue engineering. Foams can be fabricated by gas foaming, freeze drying, or porogen leaching Sproule et al, 2004;Schoof et al, 2001;Ma and Zhang, 2001;Claase et al, 2003;Sarazin and Favis, 2003). Textile scaffolds can be produced by wet or melt spinning, creating fibers that are randomly deposited on top of each other, woven, or knitted (Cima et al, 1991;Freed et al, 1994;Niklason and Langer, 1997).…”