Tissue Engineered Intervertebral Disc by Atelocollagen Scaffolds and Growth Factors / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: In vitro experimental study. OBJECTIVES: To examine the cellular proliferation, synthetic activity and phenotypical expression of intervertebral disc (IVD) cells seeded on types I and II atelocollagen scaffolds, with the stimulation of TGF-beta1 and BMP-2. SUMMARY OF LITERATURE REVIEW Recently, tissue engineering is regarded as a new experimental technique for the biological treatment of degenerative IVD diseases, and has been highlighted as a promising technique for the regeneration of tissues and organs in the human body. Research on cell transplantation in artificial scaffolds has provided that the conditions for tissue engineering have to be equilibrated, including the cell viability and proliferation, maintenance of characteristic phenotype, suitable scaffolds in organisms and biologically stimulated growth factor. MATERIAL AND METHOD: Lumbar IVD cells were harvested from 10 New Zealand white rabbits, with the nucleus pulposus cells isolated by sequential enzymatic digestion. Each of 1% types I and II atelocollagen dispersions were poured into a 96-well plate (diameter 5 mm), frozen at -70 degrees C, and then lyophilized at -50 degrees C. Fabricated porous collagen matrices were made using the cross-linking method. Cell suspensions were imbibed by surface tension into a scaffold consisting of atelocollagen. The cell cultured scaffolds were then treated with TGF-beta1 (10 ng/ml) or BMP-2 (100 ng/ml) or both. After 1 and 2 week culture periods, the DNA synthesis was measured by [3H] thymidine incorporation, and newly synthesized proteoglycan by incorporation of [35S] sulphate. Reverse transcription-polymerase chain reactions for the mRNA expressions of type I and II collagen, aggrecan and osteocalcin were performed. The inner morphology of the scaffolds was determined by scanning electron microscopy (SEM). RESULTS: The IVD cultures in collagen type II with TGF-beta1 demonstrated an increase in proteoglycan synthesis and up regulation of aggrecan and types I and II collagen mRNA expressions compared to the control. IVD cultures in the type I atelocollagen scaffold with growth factors exhibited an increase in DNA synthesis and up regulation of the type II atelocollagen mRNA expression. With all combinations of growth factor, the IVD cultures in types I and II atelocollagen scaffolds showed no up regulation of the osteocalcin mRNA expression. Furthermore, there was no synergistic effect of TGF-beta1 and BMP-2 in the matrix synthesis or for the mRNA expression of the matrix components. CONCLUSIONS: Nucleus pulposus cells from rabbit were viable in atelocollagen types I and II atelocollagen scaffolds. The type I atelocollagen scaffold was suitable for cell proliferation, but the type II atelocollagen scaffold was more suitable for extracellular matrix synthesis. The IVD cells in both scaffolds were biologically responsive to growth factors. Taken together, nucleus pulposus cells in atelocollagen scaffolds, with anabolic growth factors, provide a mechanism for tissue engineering of IVD cells.