Survival and Differentiation of Cultured Marrow Stromal Cells Transplanted Autologously in Intervertebral Discs of Rabbits

Kim, Seok Jung; Kim, Ki Won; Lee, Wha Sung; Kim, Tac Soo; Park, Sang Eun; Rhee, Seung Koo

Abstract

The purpose of this experiment was to assess the survival and differentiation of the cultured and autogenously innoculated marrow stromal cells in rabbit discs. The marrow stromal cells harvested from the rabbits ilia were cultivated for eight days. With addition of 500 micro gram of L-ascorbic acid and 10microliter of 10-5M dexamethasone, the cells were differentiated into osteoblasts. At the 8th day of primary culture, the osteoblasts were concentrated, innoculated into 5x5x5 mm sized gelfoam blocks and were immersed in culture medium for additional 48 hours, not being evacuated but for correct positioning of cultured cells into the rabbit disc during the experiment. 9 rabbits underwent two operations at two lumbar disc levels: one for incision of annulus fibrosus only(control group), and the other for insertion of osteoblast gelfoam composite graft(experimental group). The disc samples were obtained at postoperative 4, 8 and 12 weeks and were examined with H-E, Safranin-O and Masson's trichrome stains. At 4 weeks, there was a marked chondrocyte metaplasia in the experimental group, but few in the control group. Within the cartilagenous tissues, the evidences of enchondral ossification and vascular ingrowth into the discs were found in discs of experimental group at both 8 weeks and more prominently 12 weeks. The ossification occurred mainly at the site of implantation, but a few along the anterior longitudinal ligament and anterior margin of the vertevral end plate. The results suggest that marrow stromal cells survived and induced the enchondral ossification in an autologous intervertebral discs of rabbits, and the cultured osteoblasts in gelfoam composite graft could be used clinically for stabilizing the degenerated intervertebral disc or for fusion of segmental spinal instabilities.