Delivering growth factors through a polymeric scaffold to cell cultures containing both nucleus pulposus and annulus fibrosus

Abstract

AIM: To design a novel, polyvinyl alcohol (PVA)-based polymeric scaffold that permits the controlled release of insulin-like growth factor 1 (IGF-1)/bone morphogenetic protein (BMP)-2 following intervertebral disc administration. MATERIAL and METHODS: The drug delivery system was composed of two different solutions that formed a scaffold within seconds of coming into contact with each other. Swelling, pH, and temperature tests and analysis of the controlled release of growth factors (GFs) from this system were performed. The release kinetics of the GFs were determined through enzyme-linked immunosorbent assay (ELISA). Cell proliferation and viability were monitored with microscopy and analyzed using an MTT assay and acridine orange/propidium iodide (AO/PI) staining. Chondroadherin (CHAD), hypoxia inducible factor-1 alpha (HIF-1α), and collagen type II (COL2A1) gene expressions were determined with quantitative real-time polymerase chain reaction (qRT-PCR) analysis to show the effects of IGF-1/BMP-2 administration on annulus fibrosus cell (AFC)/nucleus pulposus cell (NPC) cultures. For the statistical evaluation of the obtained data, experimental groups were compared with a post hoc Tukey's test following an analysis of variance. RESULTS: The scaffold allowed for the controlled release of IGF-1 and BMP-2 in different time intervals. It was observed that as the application time increased, the number of cells and the degree of extracellular matrix development increased in AFC/NPC cultures. AO/PI staining and an MTT analysis showed that cells retained their specific morphology and continued to proliferate. It was observed that HIF-1α and CHAD expression increased in a time-dependent manner, and no COL2A1 expression in the AFC/ NPC cultures was observed. CONCLUSION: The designed scaffold may be used as an alternative method for intervertebral disc administration of GFs after further in vivo studies. Such prototype scaffolds may be an innovative technology in targeted drug therapies after reconstructive neurosurgical interventions.