Evaluation of bioresorbable polymers of lactic acid in a culture of human bone marrow cells.

Long term cultures of human bone marrow cells on poly(L-lactide-co-D,L-lactide) 70:30 and 90:10 plates were observed by means of scanning electron microscopy (SEM), SEM-EDX (SEM combined with energy dispersive X-ray analysis), flow cytometry, histochemical stainings, and culture medium analysis. After 14 days culture, cell numbers were only slightly lower compared with our reference material, hydroxyapatite, and much higher compared with polyethylene. There was evidence of collagenous matrix production with osteoblast activity. Acridine orange stainings as well as flow cytometry after incubation with propidium iodide showed only a few non-viable cells. By means of flow cytometry, we found about 30% of cells with granulocyte-markers, some monocyte-derived cells, and only small amounts of lymphocytes. After 9 weeks culture, there was evidence of calcium-phosphate deposition with extracellular matrix. There were only slight differences between the two tested polymers. Our culture system with human bone marrow cells plated on two bioresorbable polymers suggests a biocompatibility almost as good as hydroxyapatite, which is usually well tolerated. There was even evidence of mineralized collagenous matrix after some weeks of culture, which was detected earlier than the mineralization of cell-free controls.