Cartilage is often needed for tissue replacement in a patient due to injury or disease. At the University of Massachusetts Medical School, work is being done on culturing cartilage cells, or chondrocytes, in a bioreactor. A bioreactor is a vessel that holds chondrocytes and provides them with nutrients through media circulation. These chondrocytes are cultured on polymeric scaffolding of poly(glycolic acid) (PGA) coated with different percentages of poly(L-lactic acid) (PLLA). This scaffolding was studied to discover its degradation rate in media and permeability. Also observed with these studies were the pH change as the material degrades, and the porosity of the substance. The degradation of the polymer was measured over nine weeks by weighing the material repetitively. The pH of the media that the polymer was contained in was measured simultaneously. The porosity was found for use in the calculation for permeability. Permeability was found through measuring the relation of flow rate of the media through the bioreactor and pressure drop through the reactor. The PGA scaffolds with higher percentages of PLLA coating were found to degrade slower and be less permeable, while the scaffolds with low percentages of coating, or no coating degraded more rapidly and were more permeable. Degradation rate of the scaffold is important to know so that it can be related to the growth rate of the cells being cultured, chondrocytes or other. The permeability of the scaffolds will allow one to know the pressure if a flow rate is set, or vice versa. This project revealed information important not only to the University of Massachusetts Medical School, but also to any research groups that work with PGA scaffolding to culture tissue.
Worcester Polytechnic Institute
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