Temperature Effects on Bioactivity of Growth Factor-Loaded Tissue Engineering Scaffolds

Poly(lactic-co-glycolic acid) (PLGA) is a polymer commonly used as a scaffold in tissue engineering because it exhibits biodegradable and biocompatible properties. PLGA allows for the encapsulation of growth factors, such as insulin-like growth factor I (IGF-I), which has been shown to stimulate the synthesis of cartilage. The components of cartilage that are used as markers for cartilage growth are proteoglycan and type-II collagen, which can be measured and monitored using a variety of assays. The objective was to determine if there is an effect of temperature on IGF-I after being encapsulated in a PGLA scaffold and it’s ability to increase cell proliferation and therefore cartilage growth. In this study an IGF-I solution was incubated at various temperatures in order to find the range that IGF-I can withstand. To evaluate the effectiveness of IGF-I, this solution was added onto cells and monitored for DNA production in comparison to the control, which contained no IGF-I. It was found that IGF-I could withstand up to 50°C and still maintain bioactivity. Afterwards, the IGF-I was encapsulated into PLGA microspheres and fabricated into scaffolds. These scaffolds were then placed in a buffer solution, which was changed every 2-3 days. The released supernatant was then analyzed for IGF-I content to determine the rate of release and was also added onto cells to verify that the IGF bioactivity was not lost due to scaffold fabrication. As a final evaluation, bone marrow cells were seeded onto the IGF-I-loaded scaffolds to evaluate the effect of the added IGF, which showed an increase in glycosaminoglycan and DNA content at 3 and 4 weeks compared to the blank scaffolds, concluding that IGF-I cannot only withstand increased temperatures but that it does have a positive effect on cartilage growth.