In Vivo Osteogenesis in Porous Hydroxyapatite Scaffold Processed in Hyaluronic Acid Solution

Abstract

Porous hydroxyapatite (HA) scaffolds were processed in hyaluronic acid solution. Bone marrow cells obtained from the bone shaft of femurs of Fischer 344 rats at 1×106/ml concentration were seeded in pores of the scaffolds. The scaffolds were implanted in the dorsal subcutaneous tissue of rats for 2, 4, 6 or 8 weeks. Removed HA scaffolds at 2 and 4 week after dorsal subcutaneous implantation were histologically examined. At all experimental periods, osteocalcin in the scaffold was immunochemically measured for the quantitative analysis of osteogenesis by bone marrow cells in the porous HA scaffolds. Moreover, value of alkaline phosphatase (ALP) activity in the scaffolds was measured. Osteocalcin measured in scaffolds without bone marrow cells was 1.3 ng in an average and the ALP activity was 62.2 μmol at 4 week. In hyaluronic acid processed scaffold with bone marrow cells, quantity of osteocalcin increased from 1.6 ng at 2 week to 2.2 ng at 4 week after implantation of the scaffold. Histologically, many pores containing bone in the scaffolds immersed in hyaluronic acid solution were detected. Significant difference of the quantity of osteocalcin was recognized between 2 and 4 week implantation. There was no significant difference in the quantity of osteocalcin between the scaffolds implanted for 4 and 8 weeks. Value of ALP activity of the scaffold implanted for 4 weeks showed significant difference comparing with that implanted for 6 and 8 weeks. From the results of this study, quantitative increase of the bone formation in the pores of HA scaffolds would be able to observe from 6 to 8 weeks after implantation on the scaffolds by immersion in hyaluronic acid solution