Formation of bone extracellular matrix in a rotational bioreactor: Preseeding of human mesenchymal stromal cells on a thin polymer scaffold

BACKGROUND: Periprosthetic osteolysis is known to be the main reason for aseptic instability after the arthroplasty or dental implantation. The use of tissue-engineered scaffolds that allow bone formation area, produced using flow or rotational bioreactor, seems to be a promising approach for such bone lesions treatment. OBJECTIVE: To evaluate the bone neo-extracellular matrix formation within the three-week culture of a scaffold in a coaxial rotational bioreactor generating the preliminary mathematically modelled FSS values with the aim to develop a tissue-engineered scaffold for periprosthetic osteolysis prevention, but reactor critical characteristics like fluid shear stress (FSS) should be fine-tuned to achieve good cell density and prevent cell loss by the scaffold. METHODS: Thin film biodegradable polymer carrier, produced with electrospun and then seeded with hMSCs (human mesenchymal stromal cell) and culture for three weeks in rotational bioreactor, which generates the preliminary math model-calculated FSS from 4 to 8 mPa. Results were assessed with laser scanning confocal microscopy with immunofluorescence, and electron scanning microscopy with spectroscopy. RESULTS: After two weeks of culture, there were no significant differences between the density of hMSC cultured in the static conditions and bioreactor but after 3 weeks the cell density in the bioreactor increased by 35% compared to the static conditions (up to 3.53×106±462 per 1cm2, P<0.001). The immunofluorescence intensity exhibited by type I collagen after two and three weeks of culture increased 2.5-fold (48.3±0.39 a.u., P<0.001) and 1.31-fold (74.0±0.29 a.u., P<0.001) in the bioreactor, but for osteopontin after 3 weeks of culture in the static conditions was similar to those in the bioreactor. CONCLUSIONS: Optimization of the reactor characteristics with the mathematically modelled FSS values could significantly improve cell proliferation, differentiation, and enhanced formation of the neo-extracellular matrix within 3 weeks in the rotational bioreactor.