MG-63 Osteoblast Culture on Biodegradable Textiles for Bone Tissue Regeneration

The primary aim of bone scaffold is to restore, maintain and improve the structure and properties of damaged bones. The scaffold acts as a 3-D template for guided tissue-engineering and provides an excellent transition from in vitro to in vivo systems, avoiding auto- or allo-grafting treatments, both associated with serious limitations. The pore size of the scaffold must be large enough to allow cell migration and proliferation through the structure, but small enough to provide sufficient specific area for cell attachment. In this work, degradable poly(lactic acid) (PLA) yarns were knitted into complexes superstructures and evaluated as 3-D scaffold to promote cell bone reconstruction.
PLA fabrics were knitted from multi-filaments in a double layer interlock structure to produce a weft knit. The fabrics are made of two porosities, one defined by the open space inside a loop (~1mm) and the second by the distance between the filaments (1-10 µm), with high control and reproducibility inherent to the manufacturing process. Human MG-63 osteoblast-like cells were seeded on PLA textiles and cell viability and proliferation were evaluated using MTS (tetrazolium salt) assays, DNA quantitative analysis (hoechst), fluorescence staining (acridine orange) and scanning electron microscopy. Alkaline Phosphatase activity in cell lysates was also investigated.
After 3 days of culture, MG-63 fully expressed their fibroblastic phenotype. Although the number of cells was high, mitochondrial activity was shown to be reduced when cells are on the PLA fibres (compared to culture on a glass slide). This may be due the release of lactic acid by slow hydrolysis of PLA ester-bonds. Only a small population of cells was dead. Furthermore, it could be due to cells in a less active phase, such as cells entering the G0 phase, or in a maturing phase. From 6 to 12 days, the number of cell inside the PLA fabrics increased and typical fibroblastic morphology was maintained. Cells were mainly observed in the spaces between fibres. After 24 days of culture, MG-63 colonization is covering all the PLA knit. Small granular structures are present on the cell surface and low ALP concentration is detected, indicating the beginning of the differentiation process, rather than a toxic effect of PLA hydrolysis.
This work shows that knitted PLA fabrics, seeded with autogeneous osteoblast cells can potentially be used as tissue-engineered implants for the treatment of bone defects.