Tesis doctoral de Martin Andreas Koch
Large bone defects constitute a challenge for the clinical field, because they cannot be repaired by the body itself, but require the implantation of suitable bone grafts. To overcome the drawbacks of grafts from autologous or allogous sources, modern bone tissue engineering aims to replace lost tissue by cultivating cells in vitro on porous biomaterials. The cell culture on large porous scaffolds has shown to be difficult, requiring bioreactors, which are used for tissue culture and the study of cell behaviour in 3d scaffolds. Of special interest is the mechanical conditioning of the cultured tissue for bioreactor-based bone tissue engineering, which is able to enhance the osteogenic potential of the synthetic grafts. in this work two bioreactor systems were developed to allow insight into bioactive properties of different scaffold materials and the mechanoregulation of cell or tissue behaviour. An in vitro perfusion bioreactor system was developed for the cell seeding and culture on porous biomaterial cylinders. Several studies for the determination of applicable cell seeding parameters were conducted, as well as experiments of cell culture under steady fluid flow with additional mechanical stimulation by alternating fluid flow. A bone chamber system was developed as an in vivo bioreactor. The system produced a large bone defect in dog tibia and allowed the repeated implantation of large porous scaffolds of different material compositions. the ingrowing tissue was observed to allow conclusions about osteoconductive or osteinductive properties of the scaffolds. Additionally a compression device was developed to apply cyclic loading on the scaffolds in vivo to study the effect of mechanical stimulation on tissue development. the studies with the developed in vitro perfusion bioreactor system have shown that it is possible to seed cells throughout large porous scaffolds, which is deemed crucial for the further cell culture. The long time cell culture showed the proliferation of mesenchymal stem cells up to two weeks. The stimulation pattern used in the study enhanced the expression of osteocalcin, indicating an enhanced cell activity, but the absence of runx2 and collagen i expression rendered the determination of differentiation inconclusive. the developed bone chamber system proved to be functional in the surgical environment during the in vivo experiments. Occurring complications during the experiments did not allow the application of the cyclic loading of implanted scaffolds. Delayed bone formation due to created bone defect and remaining scaffold material did not allow final conclusions about the scaffold material properties. Nevertheless the study provides input for further development of the device and clinical protocol. the conducted studies constitute a novelty regarding the creation of bioreactors for the study of synthetic porous scaffolds of large dimensions in vitro and in vivo. The developed systems form the basis for further studies in mechanobiology of bone cells and tissue.
Datos académicos de la tesis doctoral «Development of in vitro and in vivo bioreactors for bone tissue engineering«
- Título de la tesis: Development of in vitro and in vivo bioreactors for bone tissue engineering
- Autor: Martin Andreas Koch
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 23/04/2010
Dirección y tribunal
- Director de la tesis
- Damien Lacroix
- Tribunal
- Presidente del tribunal: josep antoni Planell estany
- elisabet Engel lópez (vocal)
- melba Navarro toro (vocal)
- paulo Antonio Netti (vocal)