Abstract
In many tissue engineering approaches, the basic difference between in vitro and in vivo conditions for cells within three-dimensional (3D) constructs is the nutrition flow dynamics. To achieve comparable results in vitro, bioreactors are advised for improved cell survival, as they are able to provide a controlled flow through the scaffold. We hypothesize that a bioreactor would enhance long-term differentiation conditions of osteogenic cells in 3D scaffolds. To achieve this either primary rat osteoblasts or bone marrow stromal cells (BMSC) were implanted on uniform-sized biphasic calcium phosphate (BCP) scaffolds produced by a 3D printing method. Three types of culture conditions were applied: static culture without osteoinduction (Group A); static culture with osteoinduction (Group B); dynamic culture with osteoinduction (Group C). After 3 and 6 weeks, the scaffolds were analysed by alkaline phosphatase (ALP), dsDNA amount, SEM, fluorescent labelled live-dead assay, and real-time RT-PCR in addition to weekly alamarBlue assays. With osteoinduction, increased ALP values and calcium deposition are observed; however, under static conditions, a significant decrease in the cell number on the biomaterial is observed. Interestingly, the bioreactor system not only reversed the decreased cell numbers but also increased their differentiation potential. We conclude from this study that a continuous flow bioreactor not only preserves the number of osteogenic cells but also keeps their differentiation ability in balance providing a suitable cell-seeded scaffold product for applications in regenerative medicine.
Highlights
Bone tissue engineering is intended to treat a bone defect by application of a suitable biomaterial along with osteo-inducing factors or osteogenic cells
bone marrow stromal cells (BMSC) under dynamic culture conditions showed comparable potential whereas a significant difference was observed in static culture, especially following osteoinductive stimuli
The compressive strength of the 3D printed porous biphasic calcium phosphate (BCP) scaffolds was about 3.5 MPa, which is in the range of normal cancellous bone
Summary
Bone tissue engineering is intended to treat a bone defect by application of a suitable biomaterial along with osteo-inducing factors or osteogenic cells. A biomaterial for this purpose needs to possess appropriate porosity for the ingrowing tissues to invade and. After implementation of low-temperature processes, this technology might allow spatially controlled application of growth factors and even direct printing of cells within 3D hydrogel structures [4]. Most of the established scaffold fabrication techniques mix the components thoroughly, so that they are distributed uniformly. Biological tissues are usually composed of a differentiated architecture based on different cell layers and spatially defined protein composition. The uniformity of currently established fabrication methods could not mimic the non-uniform architecture of the defect tissues
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